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Sample records for masked helium implantation

  1. Patterned Exfoliation of GaAs Based on Masked Helium Implantation and Subsequent Rapid Thermal Annealing

    NASA Astrophysics Data System (ADS)

    Woo, H. J.; Choi, H. W.; Kim, G. D.; Hong, W.; Kim, J. K.

    2009-03-01

    A method of patterning single crystal GaAs based on ion implantation induced selective area exfoliation is suggested. Samples were implanted with 200-500 keV helium ions to a fluence range of 2-4×1016He+/cm2 at room temperature through masks of Ni mesh (40 μm opening) or stainless steel wire (50 μm in diameter), and subsequent rapid thermal annealing at 350-500□ resulted in expulsion of ion beam exposed material. The influences of ion energy, ion fluence, implantation temperature, subsequent annealing conditions (temperature and ramp rate), and mask pattern and its orientation with GaAs lattice on the patterned exfoliation were examined.

  2. Patterned Exfoliation of GaAs Based on Masked Helium Implantation and Subsequent Rapid Thermal Annealing

    SciTech Connect

    Woo, H. J.; Choi, H. W.; Kim, G. D.; Hong, W.; Kim, J. K.

    2009-03-10

    A method of patterning single crystal GaAs based on ion implantation induced selective area exfoliation is suggested. Samples were implanted with 200-500 keV helium ions to a fluence range of 2-4x10{sup 16} He{sup +}/cm{sup 2} at room temperature through masks of Ni mesh (40 {mu}m opening) or stainless steel wire (50 {mu}m in diameter), and subsequent rapid thermal annealing at 350-500{open_square} resulted in expulsion of ion beam exposed material. The influences of ion energy, ion fluence, implantation temperature, subsequent annealing conditions (temperature and ramp rate), and mask pattern and its orientation with GaAs lattice on the patterned exfoliation were examined.

  3. Forward masking in different cochlear implant systems

    NASA Astrophysics Data System (ADS)

    Boëx, Colette; Kós, Maria-Izabel; Pelizzone, Marco

    2003-10-01

    The goal of this study was to evaluate, from a psychophysical standpoint, the neural spread of excitation produced by the stimulation of different types of intracochlear electrode arrays: the Ineraid™, the Clarion™ S-Series on its own or with the Electrode Positioning System (EPS), and the Clarion™ HiFocus-I with the EPS. The EPS is an independent silicone part designed to bring the electrode array close to the modiolus. Forward masking was evaluated in 12 adult subjects (3 Ineraid™, 4 Clarion™ S-Series, 3 Clarion™ S-Series+EPS, 3 HiFocus-I+EPS) by psychophysical experiments conducted using trains of biphasic stimuli (813 pulses per second, 307.6 μs/phase). Masker signals (+8 dB re: threshold, 300 ms) were applied to the most apical electrode. Probe signals (30 ms, 10-ms postmasker) were delivered to more basal electrodes. Masked and unmasked detection thresholds of probe signals were measured. For both Clarion™ HiFocus-I subjects, measurements were conducted in both monopolar and bipolar stimulus configurations. No major differences were found in forward masking between the different intracochlear electrode arrays tested in the monopolar configuration at suprathreshold levels equivalent to those used in speech-coding strategies, but significant differences were found between subjects. A significant negative correlation also was found between the level of forward masking and the consonant identification performance. These measurements showed that the neural spread of excitation was more restricted in the bipolar configuration than in the monopolar configuration for HiFocus-I subjects. It was found that CIS strategies implemented without using apical electrodes, which showed high levels of masking, could improve consonant identification.

  4. Multi-part mask for implanting workpieces

    DOEpatents

    Webb, Aaron P.; Carlson, Charles T.

    2016-05-10

    A multi-part mask has a pattern plate, which includes a planar portion that has the desired aperture pattern to be used during workpiece processing. The multi-part mask also has a mounting frame, which is used to hold the pattern plate. Prior to assembly, the pattern plate has an aligning portion, which has one or more holes through which reusable alignment pins are inserted. These alignment pins enter kinematic joints disposed on the mounting frame, which serve to precisely align the pattern plate to the mounting frame. After the pattern plate has been secured to the mounting frame, the aligning portion can be detached from the pattern plate. The alignment pins can be reused at a later time. In some embodiments, the pattern plate can later be removed from the mounting frame, so that the mounting frame may be reused.

  5. Helium and deuterium implantation in tungsten at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Cipiti, B. B.; Kulcinski, G. L.

    2005-12-01

    High temperature helium and deuterium implantation on tungsten has been studied using the University of Wisconsin inertial electrostatic confinement device. Helium or deuterium ions from a plasma source were driven into polished tungsten powder metallurgy samples. Deuterium implantation did not damage the surface of the specimens at elevated temperatures (˜1200 °C). Helium implantation resulted in a porous surface structure above 700 °C. A helium fluence scan, ion energy scan, and temperature scan were all completed. With 30 keV ions, the pore formation started just below 4 × 10 16 He +/cm 2. The pore size increased and the pore density decreased with increasing fluence and temperature. The energy scan from 20 to 80 keV showed no consistent trend.

  6. Evolution of defects in silicon carbide implanted with helium ions

    NASA Astrophysics Data System (ADS)

    Zhang, Chonghong; Song, Yin; Yang, Yitao; Zhou, Chunlan; Wei, Long; Ma, Hongji

    2014-05-01

    Effects of accumulation of radiation damage in silicon carbide are important concerns for the use of silicon carbide in advanced nuclear energy systems. In the present work lattice damage in silicon carbide crystal (4H type) implanted with 100 keV 4He+ ions was investigated with Rutherford backscattering spectrometry in channeling geometry (RBS/c) and positron beam Doppler broadening spectrometry (PBDB). Helium implantation was performed at the specimen temperature of 510 K to avoid amorphization of the SiC crystal. Fluences of helium ions were selected to be in the range from 1 × 1016 to 3 × 1016 ions cm-2, around the dose threshold for the formation of observable helium bubbles under transmission electron microscopes (TEM). The RBS/c measurements show distinctly different annealing behavior of displaced Si atoms at doses below or above the threshold for helium bubble formation. The RBS/c yield in the peak damage region of the specimen implanted to 3 × 1016 He-ions cm-2 shows an increase on the subsequently thermal annealing above 873 K, which is readily ascribed to the extra displacement of Si atoms due to helium bubble growth. The RBS/c yield in the specimen implanted to a lower ion fluence of 1.5 × 1016 He-ions cm-2 decreases monotonously on annealing from ambient temperatures up to 1273 K. The PBDB measurements supply evidence of clustering of vacancies at temperatures from 510 to 1173 K, and dissociation of vacancy clusters above 1273 K. The similarity of annealing behavior in PBDB profiles for helium implantation to 1 × 1016 and 3 × 1016 ions cm-2 is ascribed to the saturation of trapping of positrons in vacancy type defects in the damaged layers in the specimens helium-implanted to the two dose levels.

  7. Lattice site of helium implanted in magnesium aluminate spinel

    NASA Astrophysics Data System (ADS)

    Alien, W. R.

    1993-01-01

    The lattice site of helium implanted at 60 keV in magnesium aluminate spinel (MgAl 2O 4) has been investigated with channeling effect measurements that apply the ion-induced 3He(d, p) 4He nuclear reaction. Within the spinel crystal structure, numerous interstices characterized by octahedral anion coordination are intrinsically unfilled by cations. For implantation at 300 K, a typical helium atom locates centrally in one of these vacant octahedral interstices with a probability of approximately 95%. Significant occupation of other lattice sites of either high or low symmetry was rejected. In particular, helium neither clusters in defect complexes nor locates in tetrahedral interstices or substitutional sites.

  8. Forward-masked spatial tuning curves in cochlear implant users

    PubMed Central

    Nelson, David A.; Donaldson, Gail S.; Kreft, Heather

    2008-01-01

    Forward-masked psychophysical spatial tuning curves (fmSTCs) were measured in twelve cochlear-implant subjects, six using bipolar stimulation (Nucleus devices)and six using monopolar stimulation (Clarion devices). fmSTCs were measured at several probe levels on a middle electrode using a fixed-level probe stimulus and variable-level maskers. The average fmSTC slopes obtained in subjects using bipolar stimulation (3.7 dB/mm) were approximately three times steeper than average slopes obtained in subjects using monopolar stimulation (1.2 dB/mm). Average spatial bandwidths were about half as wide for subjects with bipolar stimulation (2.6 mm) than for subjects with monopolar stimulation (4.6 mm). None of the tuning curve characteristics changed significantly with probe level. fmSTCs replotted in terms of acoustic frequency, using Greenwood’s [J. Acoust. Soc. Am. 33, 1344–1356 (1961)] frequency-to-place equation, were compared with forward-masked psychophysical tuning curves obtained previously from normal-hearing and hearing-impaired acoustic listeners. The average tuning characteristics of fmSTCs in electric hearing were similar to the broad tuning observed in normal-hearing and hearing-impaired acoustic listeners at high stimulus levels. This suggests that spatial tuning is not the primary factor limiting speech perception in many cochlear implant users. PMID:18345841

  9. Thermal desorption spectra from cavities in helium-implanted silicon

    NASA Astrophysics Data System (ADS)

    Cerofolini, G. F.; Calzolari, G.; Corni, F.; Frabboni, S.; Nobili, C.; Ottaviani, G.; Tonini, R.

    2000-04-01

    Thermal desorption spectra at constant ramp rate have been determined after helium implantation into bare silicon prepared for a large set of experimental conditions. The spectra can phenomenologically be classified as composed by two peaks: the α peak, centered on a temperature of 750-800°C with a shoulder extending to lower temperature (down to 550°C), and the β peak, centered on a lower temperature depending on the implantation-annealing conditions. The α peak is attributed to the emission from cavities, while the β peak is attributed to the emission from vacancylike defects. A detailed theory describing helium effusion from stable cavities as controlled by the interatomic helium-helium potential is proposed and found to reproduce accurately most of the α peaks. The postimplantation of hydrogen into samples displaying a pure β emission results in an α peak which can be described by the same model as above provided that the cavities are unstable and shrink during desorption in such a way as to maintain constant the concentration of contained helium.

  10. Evaluation of mask repair strategies via focused electron, helium, and neon beam induced processing for EUV applications

    NASA Astrophysics Data System (ADS)

    Gonzalez, C. M.; Slingenbergh, W.; Timilsina, R.; Noh, J.-H.; Stanford, M. G.; Lewis, B. B.; Klein, K. L.; Liang, T.; Fowlkes, J. D.; Rack, P. D.

    2014-04-01

    One critical area for EUV lithography is the development of appropriate mask repair strategies. To this end, we have explored etching repair strategies for nickel absorber layers and focused electron beam induced deposition of ruthenium capping layers. Nickel has higher EUV absorption than the standard TaN absorber layer and thus thinner films and improved optical quality can be realized. A thin (2.5 nm) ruthenium film is commonly used as a protective capping layer on the Mo-Si EUV multi-layer mirror which mechanically and chemically protects the multi-layers during standard mask-making procedures. The gas field ion (GFIS) microscope was used to investigate helium and neon ion beam induced etching (IBIE) of nickel as a candidate technique for EUV lithography mask editing. No discernable nickel etching was observed for helium, however transmission electron microscopy (TEM) revealed subsurface damage to the underlying Mo-Si multilayers. Subsequently, neon beam induced etching at 30 keV was investigated and successfully removed the 50 nm nickel absorber film. TEM imaging also revealed subsurface damage in the underlying Mo-Si multilayer. Two damage regimes were apparent, namely: 1) beam induced mixing of the Mo-Si layers and 2) nanobubble formation. Monte Carlo simulations were performed and the observed damage regimes were correlated to: 1) the nuclear energy loss and 2) a critical implant concentration. Electron beam induced deposition (EBID) was explored to deposit ruthenium capping/protective layers. Several ruthenium precursors were screened and so far liquid bis(ethylcyclopentyldienyl)ruthenium(II) was successful. The purity of the as-deposited nanodeposits was estimated to be 10% Ru and 90% C. We demonstrate a new chemically assisted electron beam purification process to remove carbon by-products and show that high-fidelity nanoscale ruthenium repairs can be realized.

  11. Thermal behaviour of helium-implanted spinel single crystals

    NASA Astrophysics Data System (ADS)

    Velisa, G.; Debelle, A.; Vincent, L.; Thomé, L.; Declémy, A.; Pantelica, D.; Antohe, S.

    2011-09-01

    The study of the microstructural modifications induced in spinel implanted with 4He + at 4.7 at.% and subsequently annealed at 1075 K is addressed in this paper. The combination of three analysis techniques Rutherford backscattering spectrometry in channeling geometry (RBS/C), X-ray diffraction and transmission electron microscopy was used in order to gain information about the damage depth distribution, the nature of radiation defects, and the occurrence of microstructural modifications. In as-implanted crystals the disorder level is weak, and the damage principally consists of small helium-vacancy clusters. These defects induce a tensile strain in the direction normal to the implanted crystal surface. After annealing, a surprising increase of the disorder level is measured by RBS/C. This increased backscattering yield is due to the formation of a particular type of He-vacancy clusters, namely He platelets, which also induce a relaxation of the strain.

  12. Helium ion implantation in zirconium: Bubble formation and growth

    NASA Astrophysics Data System (ADS)

    Totemeier, Aaron Robert

    To evaluate the behavior of inert helium gas bubbles in zirconium three variants of the metal were implanted with 140 keV helium ions to a total fluence of 3x1017 cm--2 and characterized in cross-section TEM in their as-implanted state as well as during annealing at different temperatures. The three zirconium alloys included high-purity crystal bar material, Zircaloy-4, and a powder-metallurgically extruded material with high carbon and oxygen concentrations. At a sample depth consistent with a helium concentration of approximately 5 atomic percent, a change in the structure of the zirconium was observed a high density region of small (4nm diameter) bubbles formed at concentrations above 10 atom percent. Initial bubble formation and growth was observed to occurred at a temperature between 400-450 °C and these initial bubbles had a unique planar geometry prior to migration and coalescence into more three-dimensional bubbles. These planar bubbles appear to be aligned with major axes parallel to the TEM specimen surface and their formation and growth is possibly due to an increase in the thermal vacancy flux within the zirconium. The observations of bubble response to high temperature annealing suggest that in zirconium, as in other metals, maximum bubble size is weakly dependent on annealing time, whereas the bubble size distribution is strongly dependent on time. Specimens that underwent a prolonged room temperature aging developed a multimodal bubble size distribution within the high density region of small bubbles, concentrated near the highest helium concentration depth.

  13. Effects of sequential tungsten and helium ion implantation on nano-indentation hardness of tungsten

    SciTech Connect

    Armstrong, D. E. J.; Edmondson, P. D.; Roberts, S. G.

    2013-06-24

    To simulate neutron and helium damage in a fusion reactor first wall sequential self-ion implantation up to 13 dpa followed by helium-ion implantation up to 3000 appm was performed to produce damaged layers of {approx}2 {mu}m depth in pure tungsten. The hardness of these layers was measured using nanoindentation and was studied using transmission electron microscopy. Substantial hardness increases were seen in helium implanted regions, with smaller hardness increases in regions which had already been self-ion implanted, thus, containing pre-existing dislocation loops. This suggests that, for the same helium content, helium trapped in distributed vacancies gives stronger hardening than helium trapped in vacancies condensed into dislocation loops.

  14. Helium reemission, desorption and microstructure evolution of graphites under helium ion implantation

    NASA Astrophysics Data System (ADS)

    Alimov, V. Kh.; Scherzer, B. M. U.; Chernikov, V. N.; Ullmaier, H.

    1995-07-01

    Helium reemission, trapping, and thermal desorption from highly ordered pyrolytic graphite (HOPG and HPG) of different orientation, polycrystalline graphite (EK98), and titanium doped graphite (RG-Ti-91) have been measured at irradiation temperatures of 300 K and 800 K. The implantation was performed with a 40 keV 4He ion beam. Detailed transmission electron microscopy (TEM) investigation of the microstructure evolution was made on the implanted specimens. He reemission from basal oriented (BO) highly oriented pyrolytic graphite is accompanied by blistering and flaking leading to repetitive gas bursts. On edge oriented (EO) pyrolytic graphite three reemission peaks are observed during room temperature implantation, the first and smallest one being assigned to He release from intrinsic lenticular cavities, the second one occurs during early bubble formation when a small amount of implanted gas still escapes accumulation, and the third and largest peak being due to He release by bubble coalescence. The He reemission rate grows very slowly at room temperature and does not reach 100% up to the highest implanted fluence of 3.5ṡ1018 He/cm2. At 800 K the He reemission rate from EO pyrolytic graphite reaches 100% immediately after starting implantation due to the high diffusive mobility of He. EK98 and RG-Ti-91 show similar reemission behaviour. No gas bursts due to blistering are observed. The initial reemission rate at 300 K is higher than in EO pyrolytic graphite due to release of He via a network of intergranular channels. At 800 K reemission is rather similar to that from EO pyrolytic graphite. No thermal desorption of He from BO HOPG up to 1200 K is observed for implanted fluences ≤1016 He/cm2. At higher fluences the onset temperature of desorption decreases from 750 K at 2ṡ1016 He/cm2 to 380 K at 1017 He/cm2 caused by thermal flaking due to pressure increase of He in submicroscopic cracks. In the other materials two desorption peaks are observed, the first one

  15. Growth of interleaved masking patterns for cochlear implant listeners at different stimulation rates

    NASA Astrophysics Data System (ADS)

    Kwon, Bom Jun; van den Honert, Chris; Parkinson, Wendy

    2003-04-01

    This study investigates the pattern of growth of masking (GOM) for interleaved masking with Nucleus cochlear implant users. For an interleaved masking paradigm, where the masker and probe overlap in a same time window, the masker may have contrasting effects: it may increase the threshold (as a masker normally does) or decrease it due to a neural summation effect, facilitating detection of the probe. Several stimulation rates and masker levels were tested to examine under what conditions what phenomenon would occur. The results indicated that, in most of the conditions, the amount of masking was positive, i.e., the facilitating effect was not consistently observed. However, the slope of the GOM appears to be dependent upon the stimulation rate: the higher the stimulation rate, the lower the slope, implying that the facilitating effect might be always present and make a bigger impact on overall masking as the stimulation rate becomes high. The amount of masking was also often nonzero (positive) even when the masker was below the threshold level. Overall, the present findings indicate that interleaved masking should be handled with care to understand cochlear implant users speech perception and improve speech coding, as it contains some nontraditional aspects of masking.

  16. Place specificity of monopolar and tripolar stimuli in cochlear implants: the influence of residual masking.

    PubMed

    Fielden, Claire A; Kluk, Karolina; McKay, Colette M

    2013-06-01

    This experiment investigated whether place specificity of neural activity evoked by cochlear implant stimulation is improved in tripolar compared to monopolar mode using a forward masking protocol addressing some limitations of previous methods of measurement and analysis. The amount of residual masking (masking remaining at long masker-probe delays) was also measured, and its potential influence on the specificity measures was evaluated. The masker stimulus comprised equally loud interleaved mono- or tripolar stimulation on two electrodes equidistant from a central probe electrode in an apical and basal direction, reducing the influence of off-site listening. The effect of masker-probe distance on the threshold shift of the tripolar probe was analyzed to derive a measure of place specificity. On average, tripolar maskers were more place specific than monopolar maskers, although the mean effect was small. There was no significant effect of masker level on specificity or on the differences observed between modes. The mean influence of residual masking on normalized masking functions was similar for the two modes and, therefore, did not influence the comparison of specificity between the modes. However, variability in amount of residual masking was observed between subjects, and therefore should be considered in forward masking studies that compare place specificity across subjects. PMID:23742363

  17. The role of helium implantation induced vacancy defect on hardening of tungsten

    SciTech Connect

    Ou, Xin; Anwand, Wolfgang Kögler, Reinhard; Zhou, Hong-Bo; Richter, Asta

    2014-03-28

    Vacancy-type defects created by helium implantation in tungsten and their impact on the nano-hardness characteristics were investigated by correlating the results from the positron annihilation spectroscopy and the nano-indentation technique. Helium implantation was performed at room temperature (RT) and at an elevated temperate of 600 °C. Also, the effect of post-annealing of the RT implanted sample was studied. The S parameter characterizing the open volume in the material was found to increase after helium irradiation and is significantly enhanced for the samples thermally treated at 600 °C either by irradiation at high temperature or by post-annealing. Two types of helium-vacancy defects were detected after helium irradiation; small defects with high helium-to-vacancy ratio (low S parameter) for RT irradiation and large defects with low helium-to-vacancy ratio (high S parameter) for thermally treated tungsten. The hardness of the heat treated tungsten coincides with the S parameter, and hence is controlled by the large helium-vacancy defects. The hardness of tungsten irradiated at RT without thermal treatment is dominated by manufacturing related defects such as dislocation loops and impurity clusters and additionally by trapped He atoms from irradiation effects, which enhance hardness. He-stabilized dislocation loops mainly cause the very high hardness values in RT irradiated samples without post-annealing.

  18. Low energy and low fluence helium implantations in tungsten: Molecular dynamics simulations and experiments

    NASA Astrophysics Data System (ADS)

    Pentecoste, L.; Brault, P.; Thomann, A.-L.; Desgardin, P.; Lecas, T.; Belhabib, T.; Barthe, M.-F.; Sauvage, T.

    2016-03-01

    300 eV Helium implantation process into tungsten at 300 K has been studied with molecular dynamic simulations (MD). Predicted retention doses were compared to that obtained from experiments performed in equivalent conditions. A saturation phenomenon of the helium retention was evidenced for a number of impinging He atoms and a retention dose similar in both, experiments and simulations. From MD simulations it is learnt that observed Helium diffusion, formation and coalescence of clusters are the phenomena leading to the flaking of the substrate. These processes could explain the saturation of the Helium retention observed experimentally at low energies.

  19. Structural investigations in helium implanted cubic zirconia using grazing incidence XRD and EXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Kuri, G.; Degueldre, C.; Bertsch, J.; Döbeli, M.

    2010-06-01

    The crystal structure and local atom arrangements surrounding Zr atoms were determined for a helium implanted cubic stabilized zirconia (CSZ) using X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) spectroscopy, respectively, measured at glancing angles. The implanted specimen was prepared at a helium fluence of 2 × 10 16 cm -2 using He + beams at two energies (2.54 and 2.74 MeV) passing through a 8.0 μm Al absorber foil. XRD results identified the formation of a new rhombohedral phase in the helium embedded layer, attributed to internal stress as a result of expansion of the CSZ-lattice. Zr K-edge EXAFS data suggested loss of crystallinity in the implanted lattice and disorder of the Zr atoms environment. EXAFS Fourier transforms analysis showed that the average first-shell radius of the Zr sbnd O pair in the implanted sample was slightly larger than that of the CSZ standard. Common general disorder features were explained by rhombohedral type short-range ordered clusters. The average structural parameters estimated from the EXAFS data of unimplanted and implanted CSZ are compared and discussed. Potential of EXAFS as a local probe of atomic-scale structural modifications induced by helium implantation in CSZ is demonstrated.

  20. Structure and micro-mechanical properties of helium-implanted layer on Ti by plasma-based ion implantation

    NASA Astrophysics Data System (ADS)

    Ma, Xinxin; Li, Jinlong; Sun, Mingren

    2008-08-01

    The present paper concentrates on structure and micro-mechanical properties of the helium-implanted layer on titanium treated by plasma-based ion implantation with a pulsed voltage of -30 kV and doses of 3, 6, 9 and 12 × 10 17 ions/cm 2, respectively. X-ray photoelectron spectroscopy and transmission electron microscopy are employed to characterize the structure of the implanted layer. The hardnesses at different depths of the layer were measured by nano-indentation. We found that helium ion implantation into titanium leads to the formation of bubbles with a diameter from a few to more than 10 nm and the bubble size increases with the increase of dose. The primary existing form of Ti is amorphous in the implanted layer. Helium implantation also enhances the ingress of O, C and N and stimulates the formations of TiO 2, Ti 2O 3, TiO, TiC and TiN in the near surface layer. And the amount of the ingressed oxygen is obviously higher than those of nitrogen and carbon due to its higher activity. At the near surface layer, the hardnesses of all implanted samples increases remarkably comparing with untreated one and the maximum hardness has an increase by a factor of up to 3.7. For the samples implanted with higher doses of 6, 9 and 12 × 10 17 He/cm 2, the local displacement bursts are clearly found in the load-displacement curves. For the samples implanted with a lower dose of 3 × 10 17 He/cm 2, there is no obvious displacement burst found. Furthermore, the burst width increases with the increase of the dose.

  1. The effects of swift heavy-ion irradiation on helium-ion-implanted silicon

    NASA Astrophysics Data System (ADS)

    Li, B. S.; Du, Y. Y.; Wang, Z. G.; Shen, T. L.; Li, Y. F.; Yao, C. F.; Sun, J. R.; Cui, M. H.; Wei, K. F.; Zhang, H. P.; Shen, Y. B.; Zhu, Y. B.; Pang, L. L.

    2014-10-01

    Cross-sectional transmission electron microscopy (XTEM) was used to study the effects of irradiation with swift heavy ions on helium-implanted silicon. <1 0 0>-oriented silicon wafers were implanted with 30 keV helium to a dose of 3 × 1016 He+/cm2 at 600 K. Subsequently, the helium-implanted Si wafers were irradiated with 792 MeV argon ions. The He bubbles and extended defects in the wafers were examined via XTEM analysis. The results reveal that the mean diameter of the He bubbles increases upon Ar-ion irradiation, while the number density of the He bubbles decreases. The microstructure of the He bubbles observed after Ar-ion irradiation is comparable to that observed after annealing at 1073 K for 30 min. Similarly, the mean size of the extended defects, i.e., Frank loops, increases after Ar-ion irradiation. Possible mechanisms are discussed.

  2. Helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure: A superior option

    PubMed Central

    XU, QI-HUA; ZHAO, CHEN; ZHU, JIAN-GANG; CHEN, MEI-JUAN; LIU, QING-HUAI

    2015-01-01

    The aim of the present study was to evaluate the efficacy of helium-neon laser therapy in the treatment of hydroxyapatite orbital implant exposure and compare the results with those of a combined drugs and surgery regimen. A total of 70 patients with hydroxyapatite orbital implant exposure in 70 eyes were randomly divided into two groups: Helium-neon laser therapy (group A) and drugs plus surgery (group B). Each group contained 35 patients. The healing rates and times of the conjunctival wound were recorded and compared following helium-neon laser treatment or the drugs plus surgery regimen. Changes in the hydroxyapatite orbital implant prior to and following helium-neon laser irradiation were analyzed. A similar animal study was conducted using 24 New Zealand white rabbits, which received orbital implants and were then received drug treatment or helium-neon therapy. In the human experiment, the rates for conjunctival wound healing were 97.14% in group A and 74.29% in group B, with a significant difference between the groups (χ2=5.71, P<0.05). Patients with mild exposure were healed after 7.22±2.11 days of helium-neon laser therapy and 14.33±3.20 days of drugs plus surgery. A statistically significant difference was found between the groups (t=8.97, P<0.05). Patients with moderate to severe exposure were healed after 18.19±2.12 days of helium-neon laser therapy and 31.25±4.21 days of drugs plus surgery. The difference between the groups was statistically significant (t=7.91, P<0.05). Enhanced magnetic resonance imaging showed that the helium-neon laser therapy significantly promoted vascularization of the hydroxyapatite orbital implant. These results, combined with pathological findings in animals, which showed that a helium-neon laser promoted vascularization and had anti-inflammatory effects, suggest that helium-neon laser irradiation is an effective method for treating hydroxyapatite orbital implant exposure, thereby avoiding secondary surgery. PMID

  3. Microstructure characterization and optical properties of sapphire after helium ion implantation

    NASA Astrophysics Data System (ADS)

    Zhong, Mian; Yang, Liang; Shen, Huahai; Liu, Wei; Xiang, Xia; Zheng, Wanguo; Guo, Decheng; Huang, Jin; Sun, Kai; Yuan, Xiaodong

    2015-06-01

    The (0 0 0 1) sapphire samples are irradiated with 60 keV helium ions at the fluences of 5 × 1016, 1 × 1017and 5 × 1017 ions/cm2 at room temperature. After implantation, two broad absorption bands at 320-460 and 480-700 nm are observed and their intensities increase with the increasing ion fluence. The grazing incidence X-ray diffraction results indicate that the {0 0 0 1} diffraction peaks of sapphire decrease and broaden due to the disorientation of the generated crystallites after ion irradiation. The microstructure evolution is examined by the scanning and transmission electron microscopes. The surface becomes rough because of the aggregation of helium bubbles and migration towards the surface. There is a lattice expansion up to ∼4.5% in the implanted area and the lattice distortion measured from dispersion of (1 1 0) diffraction is ∼4.6°. Such strain of crystal lattice is rather large and leads to contrast fluctuation at scale of 1-2 nm (the bubble size). The laser induced damage threshold (LIDT) is investigated to understand the effect of helium ion beam irradiation on the laser damage resistance of sapphire components and the results show that the LIDT decreases from 5.4 to 2.5 J/cm2 due to the absorptive color centers, helium bubbles and defects induced by helium ion implantation. The laser damage morphologies of samples before and after ion implantation are also presented.

  4. Lattice location and annealing behaviour of helium atoms implanted in uranium dioxide single crystals

    NASA Astrophysics Data System (ADS)

    Belhabib, T.; Desgardin, P.; Sauvage, T.; Erramli, H.; Barthe, M. F.; Garrido, F.; Carlot, G.; Nowicki, L.; Garcia, P.

    2015-12-01

    Helium behaviour in irradiated uranium dioxide may play an important role in the mechanical stability of nuclear fuels during and after its use in nuclear power plants. Helium migration mechanisms in bulk UO2 have already been the subject of theoretical studies but there is a lack of experimental data relating to the most stable location in the crystal. To this end, we have studied uranium dioxide samples implanted with helium ions at low fluence before and after thermal annealing in the range 600 and 800 °C. UO2 single crystals were implanted with 50 keV-3He ions at the fluence of 1 × 1015 at cm-2 and the location in the lattice of helium atoms was investigated using NRA (Nuclear Reaction Analysis) based on the reaction of 3He with deuterons (3He (d,p) 4He) in a channelling mode, recording angular scans across axes and planes. Furthermore, the uranium sub-lattice was analysed by the classical RBS method. After implantation, the experimental angular scans recorded across the main crystallographic axes and along major planes show that the helium atoms in their large majority occupy octahedral interstitial sites. No modification of the occupied crystallographic site was found after annealing at 600 °C. Conversely, no crystallographic relationship between matrix and helium signals was revealed following annealing at 800 °C. The latter feature is likely related to the clustering of implanted helium atoms into gas-filled bubbles. These experimental results have been quantified and interpreted using Monte Carlo simulations with the McChasy code.

  5. Characterization of Surface Composition and Microstructure of H13 Steel Implanted by ti Ions Using Masking Implantation Procedure

    NASA Astrophysics Data System (ADS)

    Yang, J. H.; Li, S.; Cheng, M. F.; Luo, X. D.

    Ti and C ions extracted from a metal vapor vacuum arc ion source (MEVVA) were implanted into H13 steel using a masking procedure to ensure reproducible conditions for testing and subsequent analysis. An optical interference microscope and pin-on-disc apparatus investigated the wear and friction characteristics of the steel. The Ti concentration depth profile from Rutherford backscattering spectroscopy was compared with that calculated by a TRIDYN code. It was observed by grazing-angle X-ray diffraction and transmission electron microscopy that carbide of Ti appeared in the doped region. The concentration depth profile and microstructure analysis can serve to illuminate the wear resistance improvement mechanisms of the Ti-implanted steel.

  6. Irradiation-induced microstructural change in helium-implanted single crystal and nano-engineered SiC

    NASA Astrophysics Data System (ADS)

    Chen, C. H.; Zhang, Y.; Fu, E.; Wang, Y.; Crespillo, M. L.; Liu, C.; Shannon, S.; Weber, W. J.

    2014-10-01

    Microstructural evolution induced by helium implantation and subsequent heavy ion irradiation has been investigated in single crystal and nano-engineered (NE) 3C SiC. Implantation with 65 keV He+ ions was performed at 277 °C, and the helium depth distribution was determined by elastic recoil detection analysis (ERDA). Transmission electron microscopy (TEM) could not resolve the presence of bubbles in any of the helium-implanted single crystal SiC. However, helium platelets and small dislocation loops (∼50 nm in diameter) were observed in the single crystal sample with the highest implantation fluence after 1 h annealing at 700 °C. Following irradiation with 9 MeV Au3+ ions at 700 °C, no bubbles were observed in the helium-implanted single crystal SiC, regardless of helium fluence. For the helium-implanted NE SiC, subsequent irradiation with 9 MeV Au ions to a dose of 10 dpa at 700 °C resulted in the formation and growth of bubbles, and a bimodal helium bubble size distribution was observed at the highest helium concentration (8000 appm) in the NE SiC.

  7. Blistering and cracking of LiTaO3 single crystal under helium ion implantation

    NASA Astrophysics Data System (ADS)

    Ma, Changdong; Lu, Fei; Ma, Yujie

    2015-03-01

    Blistering and cracking in LiTaO3 surface are investigated after 200-keV helium ion implantation and subsequent post-implantation annealing. Rutherford backscattering/channeling is used to examine the lattice damage caused by ion implantation. Blistering is observed through optical microscopy in a dynamic heating process. Atomic force microscopy and scanning electron microscopy measurements are used to detect the LiTaO3 surface morphology. Experimental results show that blistering and flaking are dependent on implantation fluence, beam current, and also annealing temperature. We speculate that the surface cracking of He+-implanted LiTaO3 results from the implantation-induced stress and compression.

  8. Low flux and low energy helium ion implantation into tungsten using a dedicated plasma source

    NASA Astrophysics Data System (ADS)

    Pentecoste, Lucile; Thomann, Anne-Lise; Melhem, Amer; Caillard, Amael; Cuynet, Stéphane; Lecas, Thomas; Brault, Pascal; Desgardin, Pierre; Barthe, Marie-France

    2016-09-01

    The aim of this work is to investigate the first stages of defect formation in tungsten (W) due to the accumulation of helium (He) atoms inside the crystal lattice. To reach the required implantation conditions, i.e. low He ion fluxes (1011-1014 ions.cm2.s-1) and kinetic energies below the W atom displacement threshold (about 500 eV for He+), an ICP source has been designed and connected to a diffusion chamber. Implantation conditions have been characterized by means of complementary diagnostics modified for measurements in this very low density helium plasma. It was shown that lowest ion fluxes could only be reached for the discharge working in capacitive mode either in α or γ regime. Special attention was paid to control the energy gained by the ions by acceleration through the sheath at the direct current biased substrate. At very low helium pressure, in α regime, a broad ion energy distribution function was evidenced, whereas a peak centered on the potential difference between the plasma and the biased substrate was found at higher pressures in the γ mode. Polycrystalline tungsten samples were exposed to the helium plasma in both regimes of the discharge and characterized by positron annihilation spectroscopy in order to detect the formed vacancy defects. It was found that W vacancies are able to be formed just by helium accumulation and that the same final implanted state is reached, whatever the operating mode of the capacitive discharge.

  9. Microstructure of a 14Cr-ODS ferritic steel before and after helium ion implantation

    NASA Astrophysics Data System (ADS)

    Lu, Chenyang; Lu, Zheng; Xie, Rui; Liu, Chunming; Wang, Lumin

    2014-12-01

    A 14Cr-ODS ferritic steel with the nominal compositions of Fe-14Cr-2 W-0.3Ti-0.3Y2O3 (wt.%) was produced by mechanical alloying (MA) and hot isostatic pressing (HIP). Helium ion was implanted into the 14Cr-ODS steel along with Eurofer 97 steel as reference at 400 °C to a fluence of 1 × 1017 He+/cm2. High resolution transmission electron microscopy (HRTEM), high angle annual dark field (HAADF) scanning TEM (STEM) and atom probe tomography (APT) were used to characterize the microstructure of 14Cr-ODS and Eurofer 97 steels before and after helium implantation. High-density Y-Ti-O-rich nanoclusters and Y2Ti2O7 precipitates as well as large Cr-Ti rich oxides were observed in the 14Cr-ODS steel. The average size of Y-Ti-O nanoclusters and Y2Ti2O7 precipitates is 9 nm. After helium implantation, the helium bubbles formed in the 14Cr-ODS steel exhibit the smaller size and the lower volume fraction than that in Eurofer 97 steel, indicating high-density nano-scale precipitates can effectively suppress the coarsening of helium bubbles.

  10. Study of the amorphization of surface silicon layers implanted by low-energy helium ions

    NASA Astrophysics Data System (ADS)

    Lomov, A. A.; Myakon'kikh, A. V.; Oreshko, A. P.; Shemukhin, A. A.

    2016-03-01

    The structural changes in surface layers of Si(001) substrates subjected to plasma-immersion implantation by (2-5)-keV helium ions to a dose of D = 6 × 1015-5 × 1017 cm-2 have been studied by highresolution X-ray diffraction, Rutherford backscattering, and spectral ellipsometry. It is found that the joint application of these methods makes it possible to determine the density depth distribution ρ( z) in an implanted layer, its phase state, and elemental composition. Treatment of silicon substrates in helium plasma to doses of 6 × 1016 cm-2 leads to the formation of a 20- to 30-nm-thick amorphized surface layer with a density close to the silicon density. An increase in the helium dose causes the formation of an internal porous layer.

  11. Effects of helium implantation on the tensile properties and microstructure of Ni73P27 metallic glass nanostructures.

    PubMed

    Liontas, Rachel; Gu, X Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ∼130 nm diameter Ni73P27 metallic glass nanocylinders. The nanocylinders were fabricated by a templated electroplating process and implanted with He(+) at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ∼3 atom % throughout the nanocylinders. Transmission electron microscopy imaging and through-focus analysis reveal that the specimens contained ∼2 nm helium bubbles distributed uniformly throughout the nanocylinder volume. In situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens with no sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation. PMID:25084487

  12. Effects of helium implantation on the tensile properties and microstructure of Ni₇₃P₂₇ metallic glass nanostructures

    DOE PAGESBeta

    Liontas, Rachel; Gu, X. Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R.

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ~130 nm diameter Ni₇₃P₂₇ metallic glass nano-cylinders. The nano-cylinders were fabricated by a templated electroplating process and implanted with He⁺ at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ~3 at. % throughout the nano-cylinders. Transmission electron microscopy (TEM) imaging and through-focus analysis reveal that the specimens contained ~2 nm helium bubbles distributed uniformly throughout the nano-cylinder volume. In-situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens, with nomore » sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation.« less

  13. Effects of helium implantation on the tensile properties and microstructure of Ni₇₃P₂₇ metallic glass nanostructures

    SciTech Connect

    Liontas, Rachel; Gu, X. Wendy; Fu, Engang; Wang, Yongqiang; Li, Nan; Mara, Nathan; Greer, Julia R.

    2014-09-10

    We report fabrication and nanomechanical tension experiments on as-fabricated and helium-implanted ~130 nm diameter Ni₇₃P₂₇ metallic glass nano-cylinders. The nano-cylinders were fabricated by a templated electroplating process and implanted with He⁺ at energies of 50, 100, 150, and 200 keV to create a uniform helium concentration of ~3 at. % throughout the nano-cylinders. Transmission electron microscopy (TEM) imaging and through-focus analysis reveal that the specimens contained ~2 nm helium bubbles distributed uniformly throughout the nano-cylinder volume. In-situ tensile experiments indicate that helium-implanted specimens exhibit enhanced ductility as evidenced by a 2-fold increase in plastic strain over as-fabricated specimens, with no sacrifice in yield and ultimate tensile strengths. This improvement in mechanical properties suggests that metallic glasses may actually exhibit a favorable response to high levels of helium implantation.

  14. In situ creep under helium implantation of titanium aluminium alloy

    NASA Astrophysics Data System (ADS)

    Chen, J.; Jung, P.; Nazmy, M.; Hoffelner, W.

    2006-06-01

    The intermetallic alloy Ti-47Al-2W-0.5Si (at.%) has been homogeneously implanted with 4He2+ ions under uniaxial tensile stresses from 20 to 450 MPa to a maximum dose of about 0.16 dpa (1370 appm-He) with displacement damage rates of 2 × 10-6 dpa s-1 at temperatures of 573 and 773 K. Strain under implantation was determined by Linear Variable Displacement Transformer (LVDT), while changes of microstructure were investigated after implantation by Transmission Electron Microscopy (TEM). Irradiation creep strain showed a pronounced transient behaviour, virtually independent of temperature, with a stress dependence which can be approximately described by a creep compliance of 8 × 10-6 dpa-1 MPa-1 up to stresses of 350 MPa. The microstructure of the as-received material consisted of a patch-work of mainly lamellar γ/α2 colonies and equiaxed γ-grains with islands of precipitates. Only 'black dot' damage was observed after implantation at 573 K under different stresses, while implantation at 773 K yielded a dense population of bubbles and dislocation loops, mostly mutually attached.

  15. Speech understanding performance of cochlear implant subjects using time-frequency masking-based noise reduction.

    PubMed

    Qazi, Obaid ur Rehman; van Dijk, Bas; Moonen, Marc; Wouters, Jan

    2012-05-01

    Cochlear implant (CI) recipients report severe degradation of speech understanding under noisy conditions. Most CI recipients typically can require about 10-25 dB higher signal-to-noise ratio than normal hearing (NH) listeners in order to achieve similar speech understanding performance. In recent years, significant emphasis has been put on binaural algorithms, which not only make use of the head shadow effect, but also have two or more microphone signals at their disposal to generate binaural inputs. Most of the CI recipients today are unilaterally implanted but they can still benefit from the binaural processing utilizing a contralateral microphone. The phase error filtering (PEF) algorithm tries to minimize the phase error variance utilizing a time-frequency mask for noise reduction. Potential improvement in speech intelligibility offered by the algorithm is evaluated with four different kinds of mask functions. The study reveals that the PEF algorithm which uses a contralateral microphone but unilateral presentation provides considerable improvement in intelligibility for both NH and CI subjects. Further, preference rating test suggests that CI subjects can tolerate higher levels of distortions than NH subjects, and therefore, more aggressive noise reduction for CI recipients is possible. PMID:22345522

  16. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing

    PubMed Central

    Dietz, Mathias; Hohmann, Volker; Jürgens, Tim

    2015-01-01

    For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch). Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types. PMID:26721918

  17. Spatial Release From Masking in Simulated Cochlear Implant Users With and Without Access to Low-Frequency Acoustic Hearing.

    PubMed

    Williges, Ben; Dietz, Mathias; Hohmann, Volker; Jürgens, Tim

    2015-01-01

    For normal-hearing listeners, speech intelligibility improves if speech and noise are spatially separated. While this spatial release from masking has already been quantified in normal-hearing listeners in many studies, it is less clear how spatial release from masking changes in cochlear implant listeners with and without access to low-frequency acoustic hearing. Spatial release from masking depends on differences in access to speech cues due to hearing status and hearing device. To investigate the influence of these factors on speech intelligibility, the present study measured speech reception thresholds in spatially separated speech and noise for 10 different listener types. A vocoder was used to simulate cochlear implant processing and low-frequency filtering was used to simulate residual low-frequency hearing. These forms of processing were combined to simulate cochlear implant listening, listening based on low-frequency residual hearing, and combinations thereof. Simulated cochlear implant users with additional low-frequency acoustic hearing showed better speech intelligibility in noise than simulated cochlear implant users without acoustic hearing and had access to more spatial speech cues (e.g., higher binaural squelch). Cochlear implant listener types showed higher spatial release from masking with bilateral access to low-frequency acoustic hearing than without. A binaural speech intelligibility model with normal binaural processing showed overall good agreement with measured speech reception thresholds, spatial release from masking, and spatial speech cues. This indicates that differences in speech cues available to listener types are sufficient to explain the changes of spatial release from masking across these simulated listener types. PMID:26721918

  18. Clinical evaluation of cochlear implant sound coding taking into account conjectural masking functions, MP3000™

    PubMed Central

    Buechner, Andreas; Beynon, Andy; Szyfter, Witold; Niemczyk, Kazimierz; Hoppe, Ulrich; Hey, Matthias; Brokx, Jan; Eyles, Julie; Van de Heyning, Paul; Paludetti, Gaetano; Zarowski, Andrzej; Quaranta, Nicola; Wesarg, Thomas; Festen, Joost; Olze, Heidi; Dhooge, Ingeborg; Müller-Deile, Joachim; Ramos, Angel; Roman, Stephane; Piron, Jean-Pierre; Cuda, Domenico; Burdo, Sandro; Grolman, Wilko; Vaillard, Samantha Roux; Huarte, Alicia; Frachet, Bruno; Morera, Constantine; Garcia-Ibáñez, Luis; Abels, Daniel; Walger, Martin; Müller-Mazotta, Jochen; Leone, Carlo Antonio; Meyer, Bernard; Dillier, Norbert; Steffens, Thomas; Gentine, André; Mazzoli, Manuela; Rypkema, Gerben; Killian, Matthijs; Smoorenburg, Guido

    2011-01-01

    Efficacy of the SPEAK and ACE coding strategies was compared with that of a new strategy, MP3000™, by 37 European implant centers including 221 subjects. The SPEAK and ACE strategies are based on selection of 8–10 spectral components with the highest levels, while MP3000 is based on the selection of only 4–6 components, with the highest levels relative to an estimate of the spread of masking. The pulse rate per component was fixed. No significant difference was found for the speech scores and for coding preference between the SPEAK/ACE and MP3000 strategies. Battery life was 24% longer for the MP3000 strategy. With MP3000 the best results were found for a selection of six components. In addition, the best results were found for a masking function with a low-frequency slope of 50 dB/Bark and a high-frequency slope of 37 dB/Bark (50/37) as compared to the other combinations examined of 40/30 and 20/15 dB/Bark. The best results found for the steepest slopes do not seem to agree with current estimates of the spread of masking in electrical stimulation. Future research might reveal if performance with respect to SPEAK/ACE can be enhanced by increasing the number of channels in MP3000 beyond 4–6 and it should shed more light on the optimum steepness of the slopes of the masking functions applied in MP3000. PMID:22251806

  19. Effect of helium implantation on mechanical properties of EUROFER97 evaluated by nanoindentation

    NASA Astrophysics Data System (ADS)

    Roldán, M.; Fernández, P.; Rams, J.; Jiménez-Rey, D.; Ortiz, C. J.; Vila, R.

    2014-05-01

    Helium effects on EUROFER97 mechanical properties were studied by means of nanoindentation. The steel was implanted with He ions in a stair-like profile configuration using energies from 2 to 15 MeV at room temperature. Firstly, a deep nanoindentation study was carried out on as-received state (normalized + tempered) in order to obtain a reliable properties database at the nanometric scale, including aspects such as indentation size effect. The nanoindentation hardness of tests on He implanted samples showed a hardness increase depending on the He concentration. The hardness increase follows the He implantation concentration profile with a good accuracy according to BCA calculations using MARLOWE code, considering the whole volume affected by the nanoindentation tests. The results obtained in this work shown that nanoindentation technique permits to assess any change of hardness properties due to ion implantation.

  20. Helium effects on the post-implantation creep properties and the microstructure of AISI 316L welds and parent material

    NASA Astrophysics Data System (ADS)

    Dai, Yong; Schroeder, Herbert

    1992-09-01

    The influence of implanted helium on the creep properties in electron-beam welds of the Next European Torus (NET) reference material, AISI 316L, and its parent material in the as-received condition has been investigated at 873 K. Helium degredation effects (i.e. reduced creep rupture time and creep rupture strain) are more serious in the parent material than in the welds. The fracture mode for implanted weld specimens is usually transgranular, while for the parent material specimens it is mixed trans- and intergranular. TEM investigations show that in the welds there is a lot of σ-ferrite at grain boundaries (occupying about 50% of grain boundary area) and in the interior of grains as well. Helium bubble sizes increase with increasing helium concentration, while helium bubble densities remain constant. Helium bubbles in the matrix are larger in size but much lower in density than those at boundaries or interfaces.

  1. BCA-kMC Hybrid Simulation for Hydrogen and Helium Implantation in Material under Plasma Irradiation

    NASA Astrophysics Data System (ADS)

    Kato, Shuichi; Ito, Atsushi; Sasao, Mamiko; Nakamura, Hiroaki; Wada, Motoi

    2015-09-01

    Ion implantation by plasma irradiation into materials achieves the very high concentration of impurity. The high concentration of impurity causes the deformation and the destruction of the material. This is the peculiar phenomena in the plasma-material interaction (PMI). The injection process of plasma particles are generally simulated by using the binary collision approximation (BCA) and the molecular dynamics (MD), while the diffusion of implanted atoms have been traditionally solved by the diffusion equation, in which the implanted atoms is replaced by the continuous concentration field. However, the diffusion equation has insufficient accuracy in the case of low concentration, and in the case of local high concentration such as the hydrogen blistering and the helium bubble. The above problem is overcome by kinetic Monte Carlo (kMC) which represents the diffusion of the implanted atoms as jumps on interstitial sites in a material. In this paper, we propose the new approach ``BCA-kMC hybrid simulation'' for the hydrogen and helium implantation under the plasma irradiation.

  2. Dependence of the tensile properties of 316 L parent material and welds on implanted hydrogen and/or helium

    NASA Astrophysics Data System (ADS)

    Schroeder, Herbert; Liu, Wanpei

    1992-09-01

    The interest in the low temperature tensile properties of candidate alloys for first wall and blanket structures of future fusion devices is due to the possible low pressure water cooling and the associated low operation temperature in recent design studies. Therefore, the tensile properties of hydrogen and/or helium implanted 316 L stainless steel and its weldments as a function of gas concentrations and temperature were investigated. The main effects of the implantation are hardening, resulting in large increases of the yield strength proportional to the implanted gas concentration, and a gradual decrease of the corresponding rupture strain. The ultimate tensile stresses are less affected. The effect of helium implantation seems to be more pronounced than that of hydrogen implantation. At 673 K most of the implantation induced changes are recovered. Generally parent material and welds still show large ductility (≥20%) under all conditions investigated.

  3. Irradiation hardening of ODS ferritic steels under helium implantation and heavy-ion irradiation

    NASA Astrophysics Data System (ADS)

    Zhang, Hengqing; Zhang, Chonghong; Yang, Yitao; Meng, Yancheng; Jang, Jinsung; Kimura, Akihiko

    2014-12-01

    Irradiation hardening of ODS ferritic steels after multi-energy He-ion implantation, or after irradiation with energetic heavy ions including Xe and Bi-ions was investigated with nano-indentation technique. Three kinds of high-Cr ODS ferritic steels including the commercial MA956 (19Cr-3.5Al), the 16Cr-0.1Ti and the 16Cr-3.5Al-0.1Zr were used. Data of nano-hardness were analyzed with an approach based on Nix-Gao model. The depth profiles of nano-hardness can be understood by the indentation size effect (ISE) in specimens of MA956 implanted with multi-energy He-ions or irradiated with 328 MeV Xe ions, which produced a plateau damage profile in the near-surface region. However, the damage gradient overlaps the ISE in the specimens irradiated with 9.45 Bi ions. The dose dependence of the nano-hardness shows a rapid increase at low doses and a slowdown at higher doses. An 1/2-power law dependence on dpa level is obtained. The discrepancy in nano-hardness between the helium implantation and Xe-ion irradiation can be understood by using the average damage level instead of the peak dpa level. Helium-implantation to a high dose (7400 appm/0.5 dpa) causes an additional hardening, which is possibly attributed to the impediment of motion dislocations by helium bubbles formed in high concentration in specimens.

  4. Helium effects on microstructural evolution in tempered martensitic steels: In situ helium implanter studies in HFIR

    SciTech Connect

    Yamamoto, Takuya; Odette, George R.; Miao, Pifeng; Edwards, Danny J.; Kurtz, Richard J.

    2009-04-30

    Microstructural evolutions in tempered martensitic steels (TMS) under neutron-irradiation, at fusion relevant He/dpa ratios and dpa rates, were characterized using a novel in situ He-implanter technique. F82H-mod3 was irradiated at 500 C in HFIR to a nominal 9 dpa and 190 or 380 appm He in both in the as-tempered (AT) and 20% cold-worked (CW) conditions. In all cases, a high number density of 1-2 nm He-bubbles were observed, along with fewer but larger 10 nm void-like faceted cavities. The He-bubbles form preferentially on dislocations and various interfaces. A slightly larger number of smaller He bubbles were observed in the CW condition. The lower He/dpa ratio produced slightly smaller and fewer He-bubbles. Comparisons of these observations to the results in nano-structured ferritic alloy (NFA) MA957 provide additional evidence that TMS may be susceptible to He-embrittlement as well as void swelling at fusion relevant He concentrations, while NFA are much more resistant to these degradation phenomena.

  5. Experimental investigations of helium ion implantation in the first wall of JET

    NASA Astrophysics Data System (ADS)

    Zhu, J.; McCracken, G. M.; Coad, J. P.

    1991-07-01

    3.5 MeV alpha particles will be produced in fusion reactors. Although they will be slowed down in the plasma, they will still retain some energy upon diffusing out to the wall and therefore will be expected to become implanted there. We have developed a technique for measuring the depth distribution of helium implanted in metals. The technique has been applied to the analysis of Ni and inconel samples exposed in the JET tokamak for ˜ 5000 discharges during 1987-1988 with ion cyclotron resonance heating (ICRH). Significant quantities of 3He and 4He atoms have been detected due to the use of helium both as a plasma fuel and as a minority species for ICRH. The energy distribution of the ions heated by ICRH in the plasma is expected to be similar to that characterizing the alpha particles in a reactor. The analysis shows a broad range distribution in the samples up to at least 1.0 μm in depth. Calibration of the technique has been performed using implants of monoenergetic 3He and 4He at energies of 2-50 keV and fluences of (1-5) × 10 16 ions cm -2. The results are in quite good agreement with predictions from the TRIM code. The sensitivity of the system is such that concentrations of 5 ×10 18 atoms cm˜3 ( ˜ 50 ppm) are detectable.

  6. Binaural masking level differences in actual and simulated bilateral cochlear implant listeners

    PubMed Central

    Lu, Thomas; Litovsky, Ruth; Zeng, Fan-Gang

    2010-01-01

    At present commercially available bilateral cochlear implants (CIs) improve their users’ speech understanding in noise but they employ two independent speech processors that cannot provide accurate and appropriate interaural level and time differences as seen binaurally in normal hearing (NH) listeners. Previous work suggests that binaural cues are accessible to bilateral CI users when presented to single pairs of pitch-matched electrodes, but the scope was limited and the mechanisms remained unclear. In this study, binaural masking level differences (BMLDs) were measured in five bilateral Nucleus-24 CI users over multiple pairs of pitch-matched electrodes. Average BMLD was 4.6±4.9 dB, but large individual variability prevented significance (p=0.09). Considering just the 125 Hz condition, as in previous work, phase (N0S0 vs N0Sπ) and electrode effects were significant. Compared with simulated bilateral CI users, actual bilateral CI users had proportionally higher thresholds for N0Sπ than N0S0. Together the present results suggest that the performance gap in BMLDs between CI and NH listeners is not due to a lack of sufficient acoustic cues in the temporal envelope domain but to a true binaural deficit related to a central mechanism in deprived binaural processing. PMID:20329848

  7. Helium irradiation effects on retention behavior of deuterium implanted into boron coating film by PCVD

    NASA Astrophysics Data System (ADS)

    Kodama, H.; Oyaidzu, M.; Yoshikawa, A.; Kimura, H.; Oya, Y.; Matsuyama, M.; Sagara, A.; Noda, N.; Okuno, K.

    2005-03-01

    Helium irradiation effects on the retention of energetic deuterium implanted into the boron coating film were investigated by means of X-ray photoelectron spectroscopy (XPS) and thermal desorption spectroscopy (TDS). It was found, by XPS, that the B 1s peak was shifted to lower binding energy side by He + ion irradiation and the FWHM was extended. These facts show that the some defects were introduced into the boron coating film by He + ion irradiation. From TDS experiment, the deuterium retention, especially the amount of B-D terminal bond, increased by the pre-He + ion irradiation. However, it decreased by the post-He + ion irradiation. These experimental results indicate that the B-D terminal bond was mainly influenced by the He + ion irradiation because the two neighbor B-D bonds have to dissociate simultaneously for the B-D-B bridge bond.

  8. Estimated solar wind-implanted helium-3 distribution on the Moon

    USGS Publications Warehouse

    Johnson, J. R.; Swindle, T.D.; Lucey, P.G.

    1999-01-01

    Among the solar wind-implanted volatiles present in the lunar regolith, 3 He is possibly the most valuable resource because of its potential as a fusion fuel. The abundance of 3 He in the lunar regolith at a given location depends on surface maturity, the amount of solar wind fluence, and titanium content, because ilmenite (FeTiO3) retains helium much better than other major lunar minerals. Surface maturity and TiO2 maps from Clementine multispectral data sets are combined here with a solar wind fluence model to produce a 3He abundance map of the Moon. Comparison of the predicted 3He values to landing site observations shows good correlation. The highest 3He abundances occur in the farside maria (due to greater solar wind fluence received) and in higher TiO2 nearside mare regions.

  9. Impurity gettering in silicon using cavities formed by helium implantation and annealing

    DOEpatents

    Myers, S.M. Jr.; Bishop, D.M.; Follstaedt, D.M.

    1998-11-24

    Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer. 4 figs.

  10. Impurity gettering in silicon using cavities formed by helium implantation and annealing

    DOEpatents

    Myers, Jr., Samuel M.; Bishop, Dawn M.; Follstaedt, David M.

    1998-01-01

    Impurity gettering in silicon wafers is achieved by a new process consisting of helium ion implantation followed by annealing. This treatment creates cavities whose internal surfaces are highly chemically reactive due to the presence of numerous silicon dangling bonds. For two representative transition-metal impurities, copper and nickel, the binding energies at cavities were demonstrated to be larger than the binding energies in precipitates of metal silicide, which constitutes the basis of most current impurity gettering. As a result the residual concentration of such impurities after cavity gettering is smaller by several orders of magnitude than after precipitation gettering. Additionally, cavity gettering is effective regardless of the starting impurity concentration in the wafer, whereas precipitation gettering ceases when the impurity concentration reaches a characteristic solubility determined by the equilibrium phase diagram of the silicon-metal system. The strong cavity gettering was shown to induce dissolution of metal-silicide particles from the opposite side of a wafer.

  11. Helium and neon implantation and memory observed in a quadrupole mass spectrometer

    NASA Astrophysics Data System (ADS)

    Rau, Ingo; Putzka, Alfred

    1999-07-01

    High accuracy static quadrupole mass spectrometer (QMS) measurement of helium and neon may be impaired by implantation and long lasting thermal desorption effects of the previously trapped atoms. A QMS produces only moderately accelerated ions of 100-200 eV. The ions decelerate at stainless steel surfaces somewhere in the QMS and a part of them will be trapped in surface near sites. For helium and neon most of these trapped atoms are able to desorb with time constants of several hours. This causes an memory effect which hinders high precision measurements. The trapping and desorption experiments reported here indicate that these time constants for the desorption are about 90-477 min for temperatures between 330 and 470 K. 20-60% (330 K) and 450% (470 K) of the atoms which have been trapped desorb subsequently. This could be explained by assuming self-sputtering processes. From the desorption behaviour a binding energy of 1.1 and 1.6 eV for these atoms has been estimated.

  12. Temperature dependence of helium-implantation-induced lattice swelling in polycrystalline tungsten: X-ray micro-diffraction and Eigenstrain modelling

    DOE PAGESBeta

    de Broglie, I.; Beck, C. E.; Liu, W.; Hofmann, Felix

    2015-05-30

    Using synchrotron X-ray micro-diffraction and Eigenstrain analysis the distribution of lattice swelling near grain boundaries in helium-implanted polycrystalline tungsten is quantified. Samples heat-treated at up to 1473 K after implantation show less uniform lattice swelling that varies significantly from grain to grain compared to as-implanted samples. An increase in lattice swelling is found in the vicinity of some grain boundaries, even at depths beyond the implanted layer. As a result, these findings are discussed in terms of the evolution of helium-ion-implantation-induced defects.

  13. Gas porosity evolution and ion-implanted helium behavior in reactor ferritic/martensitic and austenitic steels

    NASA Astrophysics Data System (ADS)

    Chernov, I. I.; Kalin, B. A.; Staltsov, M. S.; Oo, Kyi Zin; Binyukova, S. Yu.; Staltsova, O. S.; Polyansky, A. A.; Ageev, V. S.; Nikitina, A. A.

    2015-04-01

    The peculiarities of gas porosity formation and helium retention and release in reactor ferritic/martensitic EP-450 and EP-450-ODS and austenitic ChS-68 steels are investigated by transmission electron microscopy and helium thermal desorption spectrometry (HTDS). The samples were irradiated by 40 keV He+ ions up to a fluence of 5 · 1020 m-2 at 293 and 923 K. An nonuniform distribution of helium bubbles and high-level gas swelling in ferritic/martensitic steels were found at high-temperature helium implantation. The same irradiation conditions result in formation of uniformly distributed helium bubbles and low-level swelling in ChS-68 steel. Temperature range of helium release from EP-450-ODS steel was considerably wider in comparison to HTDS-spectra of the EP-450 steel. A considerable quantity of helium is released from ODS steel in the high-temperature range after the main peak of the HTDS-spectrum.

  14. Bending tests on T91 samples implanted with 0.25 at.% helium: Experiments and mechanical analysis

    NASA Astrophysics Data System (ADS)

    Henry, J.; Vincent, L.; Averty, X.; Marini, B.; Jung, P.

    2006-09-01

    In order to investigate helium effects on the fracture properties of martensitic mod 9Cr-1Mo (T91) steel, miniature Charpy specimens were implanted at 250 °C in the notch region to 0.25 at.% helium using a degraded 34 MeV 3He ion beam and subsequently submitted to static bending tests at room temperature. For the six implanted specimens, a 'pop-in' phenomenon, which is an arrested unstable crack extension, was systematically recorded during testing. In the implanted zones of the samples, the fracture mode was fully brittle with both intergranular and cleavage fracture, whereas for unimplanted samples tested at -170 °C, the fracture mode was found to be 100% cleavage. Finite element simulations of the tests performed on unimplanted and implanted specimens were also carried out to determine stress and strain fields at the onset of crack propagation. Based on these computations, the fracture toughness of implanted T91 was tentatively evaluated using the Beremin model of the local approach to brittle fracture.

  15. Peeling off the Mask: Pseudo Myocardial Infarction Pattern on Electrocardiogram During AICD Implantation

    PubMed Central

    Kumar, Sudeep; Kapoor, Aditya; Moorthy, Nagaraja; Lokhandwala, Yash

    2016-01-01

    Lead induced transient right bundle branch block is not uncommon during pacemaker implantation. We describe a patient with old anterior wall myocardial infarction with severe left ventricular dysfunction presenting with recurrent ventricular tachycardia who developed transient right bundle branch block and pseudomyocardial infacrction pattern during AICD implantation. PMID:25852248

  16. Effect of simultaneous helium implantation on the microstructure evolution of Inconel X-750 superalloy during dual-beam irradiation

    NASA Astrophysics Data System (ADS)

    Changizian, P.; Zhang, H. K.; Yao, Z.

    2015-12-01

    This study focuses on investigation into the effect of helium implantation on microstructure evolution in Inconel X-750 superalloy during dual-beam (Ni+/He+) irradiation. The 1 MeV Ni+ ions with the damage rate of 10-3 dpa/s as well as 15 keV He+ ions using rate of 200 appm/dpa were simultaneously employed to irradiate specimens at 400 °C to different doses. Microstructure characterization has been conducted using high-resolution analytical transmission electron microscopy (TEM). The TEM results show that simultaneous helium injection has significant influence on irradiation-induced microstructural changes. The disordering of γ‧ (Ni3 (Al, Ti)) precipitates shows noticeable delay in dose level compared to mono heavy ion irradiation, which is attributed to the effect of helium on promoting the dynamic reordering process. In contrast to previous studies on single-beam ion irradiation, in which no cavities were reported even at high doses, very small (2-5 nm) cavities were detected after irradiation to 5 dpa, which proved that helium plays crucial role in cavity formation. TEM characterization also indicates that the helium implantation affects the development of dislocation loops during irradiation. Large 1/3 <1 1 1> Frank loops in the size of 10-20 nm developed during irradiation at 400 °C, whereas similar big loops detected at higher irradiation temperature (500 °C) during sole ion irradiation. This implies that the effect of helium on trapping the vacancies can help to develop the interstitial Frank loops at lower irradiation temperatures.

  17. Strain Doping: Reversible Single-Axis Control of a Complex Oxide Lattice via Helium Implantation

    NASA Astrophysics Data System (ADS)

    Guo, Hangwen; Dong, Shuai; Rack, Philip D.; Budai, John D.; Beekman, Christianne; Gai, Zheng; Siemons, Wolter; Gonzalez, C. M.; Timilsina, R.; Wong, Anthony T.; Herklotz, Andreas; Snijders, Paul C.; Dagotto, Elbio; Ward, Thomas Z.

    2015-06-01

    We report on the use of helium ion implantation to independently control the out-of-plane lattice constant in epitaxial La0.7Sr0.3MnO3 thin films without changing the in-plane lattice constants. The process is reversible by a vacuum anneal. Resistance and magnetization measurements show that even a small increase in the out-of-plane lattice constant of less than 1% can shift the metal-insulator transition and Curie temperatures by more than 1 0 0 °C . Unlike conventional epitaxy-based strain tuning methods which are constrained not only by the Poisson effect but by the limited set of available substrates, the present study shows that strain can be independently and continuously controlled along a single axis. This permits novel control over orbital populations through Jahn-Teller effects, as shown by Monte Carlo simulations on a double-exchange model. The ability to reversibly control a single lattice parameter substantially broadens the phase space for experimental exploration of predictive models and leads to new possibilities for control over materials' functional properties.

  18. Strain Doping: Reversible Single-Axis Control of a Complex Oxide Lattice via Helium Implantation.

    PubMed

    Guo, Hangwen; Dong, Shuai; Rack, Philip D; Budai, John D; Beekman, Christianne; Gai, Zheng; Siemons, Wolter; Gonzalez, C M; Timilsina, R; Wong, Anthony T; Herklotz, Andreas; Snijders, Paul C; Dagotto, Elbio; Ward, Thomas Z

    2015-06-26

    We report on the use of helium ion implantation to independently control the out-of-plane lattice constant in epitaxial La(0.7)Sr(0.3)MnO(3) thin films without changing the in-plane lattice constants. The process is reversible by a vacuum anneal. Resistance and magnetization measurements show that even a small increase in the out-of-plane lattice constant of less than 1% can shift the metal-insulator transition and Curie temperatures by more than 100 °C. Unlike conventional epitaxy-based strain tuning methods which are constrained not only by the Poisson effect but by the limited set of available substrates, the present study shows that strain can be independently and continuously controlled along a single axis. This permits novel control over orbital populations through Jahn-Teller effects, as shown by Monte Carlo simulations on a double-exchange model. The ability to reversibly control a single lattice parameter substantially broadens the phase space for experimental exploration of predictive models and leads to new possibilities for control over materials' functional properties. PMID:26197138

  19. Surface studies and implanted helium measurements following NOVA high-yield DT experiments

    SciTech Connect

    Stoyer, M.A.; Hudson, G.B.

    1997-02-18

    This paper presents the results of three March 6, 1996 direct-drive high-yield DT NOVA experiments and provides `proof-of-principal` results for the quantitative measurement of energetic He ions. Semiconductor quality Si wafers and an amorphous carbon wafer were exposed to NOVA high-yield implosions. Surface damage was sub-micron in general, although the surface ablation was slightly greater for the carbon wafer than for the Si wafers. Melting of a thin ({approx} 0.1{mu}) layer of Si was evident from microscopic investigation. Electron microscopy indicated melted blobs of many different metals (e.g. Al, Au, Ta, Fe alloys, Cu and even Cd) on the surfaces. The yield measured by determining the numbers of atoms of implanted {sup 4}He and {sup 3}He indicate the number of DT fusions to be 9.1({plus_minus}2.3) X 10{sup 12} and DD fusions to be 4.8({plus_minus}1.0) x 10{sup 10}, respectively. The helium DT fusion yield is slightly lower than that of the Cu activation measurement, which was 1.3({plus_minus}0.l) x 10{sup 13} DT fusions.

  20. Fabrication of porous TiO2 nanorod array photoelectrodes with enhanced photoelectrochemical water splitting by helium ion implantation.

    PubMed

    Liu, Yichao; Shen, Shaohua; Ren, Feng; Chen, Jianan; Fu, Yanming; Zheng, Xudong; Cai, Guangxu; Xing, Zhuo; Wu, Hengyi; Jiang, Changzhong

    2016-05-19

    Porous photoelectrodes show high efficiency in hydrogen production by water splitting. However, fabrication of porous nanorods is usually difficult. Here, we report a simple approach to fabricate a kind of novel porous rutile titanium dioxide nanorod array by an advanced ion implantation method using multiple-energy helium ion implantation and subsequent annealing. The porous nanostructure enhances the photoelectrochemical performance of the titanium dioxide nanorod array photoelectrodes under Uv-visible light illumination, where the highest photocurrent density was relatively about 10 times higher than that of the pristine titanium dioxide nanorod array. The formation of nanocavities mainly contributes to the enhancement of the photocurrent density by trapping holes inside to separate the charge carriers. The study demonstrates that ion implantation could be an effective approach to develop novel porous nanostructural photoelectrodes for the application of hydrogen production. PMID:27145900

  1. Investigation Of Helium Implanted Fe-Cr Alloys By Means Of X-Ray Diffraction And Positron Annihilation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Novák, Patrik; Gokhman, Aleksandr; Dobročka, Edmund; Bokor, Jozef; Pecko, Stanislav

    2015-11-01

    X-ray diffraction (XRD) and positron annihilation spectroscopy (PAS) have been used for the characterization of the two binary alloys Fe-Cr with Cr content 2.36 and 8.39 wt%. The influence of ion implantation on these alloys was studied. Different implantation doses of helium, up to 0.5 C/cm2, were used to simulate neutron-induced damage in a sub-surface region. To characterize the damage, a lattice parameter, coherent domain size, residual stress and a crystallographic texture have been studied by grazing incidence X-ray diffraction (GIXRD). It was found out that these parameters showed a similar dependence on the implantation dose as the positron lifetime determined by positron annihilation spectroscopy.

  2. Spatial release from masking in children with bilateral cochlear implants and with normal hearing: Effect of target-interferer similarity

    PubMed Central

    Misurelli, Sara M.; Litovsky, Ruth Y.

    2015-01-01

    In complex auditory environments, it is often difficult to separate a target talker from interfering speech. For normal hearing (NH) adult listeners, similarity between the target and interfering speech leads to increased difficulty in separating them; that is, informational masking occurs due to confusability of the target and interferers. This study investigated performance of children with bilateral cochlear implants (BiCIs) when target and interferers were either same-sex (male) talkers, or different-sex talkers (male target, female interferer). Comparisons between children with BiCIs and NH, when matched for age, were also conducted. Speech intelligibility was measured for target and interferers spatially co-located, or spatially separated with the interferers positioned symmetrically (+90° and −90°) or asymmetrically (both at +90°, right). Spatial release from masking (SRM) was computed as the difference between co-located and separated conditions. Within group BiCI comparisons revealed that in the co-located condition speech intelligibility was worse with the same-sex vs different-sex stimuli. There was also a trend for more SRM with the same-sex vs different-sex stimuli. When comparing BiCI to NH listeners, SRM was larger for the NH groups, suggesting that NH children are better able to make use of spatial cues to improve speech understanding in noise. PMID:26233032

  3. Spatial release from masking in children with bilateral cochlear implants and with normal hearing: Effect of target-interferer similarity.

    PubMed

    Misurelli, Sara M; Litovsky, Ruth Y

    2015-07-01

    In complex auditory environments, it is often difficult to separate a target talker from interfering speech. For normal hearing (NH) adult listeners, similarity between the target and interfering speech leads to increased difficulty in separating them; that is, informational masking occurs due to confusability of the target and interferers. This study investigated performance of children with bilateral cochlear implants (BiCIs) when target and interferers were either same-sex (male) talkers, or different-sex talkers (male target, female interferer). Comparisons between children with BiCIs and NH, when matched for age, were also conducted. Speech intelligibility was measured for target and interferers spatially co-located, or spatially separated with the interferers positioned symmetrically (+90° and -90°) or asymmetrically (both at +90°, right). Spatial release from masking (SRM) was computed as the difference between co-located and separated conditions. Within group BiCI comparisons revealed that in the co-located condition speech intelligibility was worse with the same-sex vs different-sex stimuli. There was also a trend for more SRM with the same-sex vs different-sex stimuli. When comparing BiCI to NH listeners, SRM was larger for the NH groups, suggesting that NH children are better able to make use of spatial cues to improve speech understanding in noise. PMID:26233032

  4. Fabrication of porous TiO2 nanorod array photoelectrodes with enhanced photoelectrochemical water splitting by helium ion implantation

    NASA Astrophysics Data System (ADS)

    Liu, Yichao; Shen, Shaohua; Ren, Feng; Chen, Jianan; Fu, Yanming; Zheng, Xudong; Cai, Guangxu; Xing, Zhuo; Wu, Hengyi; Jiang, Changzhong

    2016-05-01

    Porous photoelectrodes show high efficiency in hydrogen production by water splitting. However, fabrication of porous nanorods is usually difficult. Here, we report a simple approach to fabricate a kind of novel porous rutile titanium dioxide nanorod array by an advanced ion implantation method using multiple-energy helium ion implantation and subsequent annealing. The porous nanostructure enhances the photoelectrochemical performance of the titanium dioxide nanorod array photoelectrodes under Uv-visible light illumination, where the highest photocurrent density was relatively about 10 times higher than that of the pristine titanium dioxide nanorod array. The formation of nanocavities mainly contributes to the enhancement of the photocurrent density by trapping holes inside to separate the charge carriers. The study demonstrates that ion implantation could be an effective approach to develop novel porous nanostructural photoelectrodes for the application of hydrogen production.Porous photoelectrodes show high efficiency in hydrogen production by water splitting. However, fabrication of porous nanorods is usually difficult. Here, we report a simple approach to fabricate a kind of novel porous rutile titanium dioxide nanorod array by an advanced ion implantation method using multiple-energy helium ion implantation and subsequent annealing. The porous nanostructure enhances the photoelectrochemical performance of the titanium dioxide nanorod array photoelectrodes under Uv-visible light illumination, where the highest photocurrent density was relatively about 10 times higher than that of the pristine titanium dioxide nanorod array. The formation of nanocavities mainly contributes to the enhancement of the photocurrent density by trapping holes inside to separate the charge carriers. The study demonstrates that ion implantation could be an effective approach to develop novel porous nanostructural photoelectrodes for the application of hydrogen production. Electronic

  5. Wafer topography modeling for ionic implantation mask correction dedicated to 2x nm FDSOI technologies

    NASA Astrophysics Data System (ADS)

    Michel, Jean-Christophe; Le Denmat, Jean-Christophe; Sungauer, Elodie; Robert, Frédéric; Yesilada, Emek; Armeanu, Ana-Maria; Entradas, Jorge; Sturtevant, John L.; Do, Thuy; Granik, Yuri

    2013-04-01

    Reflection by wafer topography and underlying layers during optical lithography can cause unwanted exposure in the resist [1]. This wafer stack effect phenomenon which is neglected for larger nodes than 45nm, is becoming problematic for 32nm technology node and below at the ionic implantation process. This phenomenon is expected to be attenuated by the use of anti-reflecting coating but increases process complexity and adds cost and cycle time penalty. As a consequence, an OPC based solution is today under evaluation to cope with stack effects involved in ionic implantation patterning [2] [3]. For the source drain (SD) ionic implantation process step on 28nm Fully Depleted Silicon-on-Insulator (FDSOI) technology, active silicon areas, poly silicon patterns, Shallow Trench Isolation (STI), Silicon-on-Insulator (SOI) areas and the transitions between these different regions result in significant SD implant pattern critical dimension variations. The large number of stack variations involved in these effects implies a complex modeling to simulate pattern degradations. This paper deals with the characterization of stack effects on 28nm node using SOI substrates. The large number of measurements allows to highlight all individual and combined stack effects. A new modeling flow has been developed in order to generate wafer stack aware OPC model. The accuracy and the prediction of the model is presented in this paper.

  6. High-resolution, high-throughput, positive-tone patterning of poly(ethylene glycol) by helium beam exposure through stencil masks.

    PubMed

    Cacao, Eliedonna E; Nasrullah, Azeem; Sherlock, Tim; Kemper, Steven; Kourentzi, Katerina; Ruchhoeft, Paul; Stein, Gila E; Willson, Richard C

    2013-01-01

    In this work, a collimated helium beam was used to activate a thiol-poly(ethylene glycol) (SH-PEG) monolayer on gold to selectively capture proteins in the exposed regions. Protein patterns were formed at high throughput by exposing a stencil mask placed in proximity to the PEG-coated surface to a broad beam of helium particles, followed by incubation in a protein solution. Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR) spectra showed that SH-PEG molecules remain attached to gold after exposure to beam doses of 1.5-60 µC/cm(2) and incubation in PBS buffer for one hour, as evidenced by the presence of characteristic ether and methoxy peaks at 1120 cm(-1) and 2870 cm(-1), respectively. X-ray Photoelectron Spectroscopy (XPS) spectra showed that increasing beam doses destroy ether (C-O) bonds in PEG molecules as evidenced by the decrease in carbon C1s peak at 286.6 eV and increased alkyl (C-C) signal at 284.6 eV. XPS spectra also demonstrated protein capture on beam-exposed PEG regions through the appearance of a nitrogen N1s peak at 400 eV and carbon C1s peak at 288 eV binding energies, while the unexposed PEG areas remained protein-free. The characteristic activities of avidin and horseradish peroxidase were preserved after attachment on beam-exposed regions. Protein patterns created using a 35 µm mesh mask were visualized by localized formation of insoluble diformazan precipitates by alkaline phosphatase conversion of its substrate bromochloroindoyl phosphate-nitroblue tetrazolium (BCIP-NBT) and by avidin binding of biotinylated antibodies conjugated on 100 nm gold nanoparticles (AuNP). Patterns created using a mask with smaller 300 nm openings were detected by specific binding of 40 nm AuNP probes and by localized HRP-mediated deposition of silver nanoparticles. Corresponding BSA-passivated negative controls showed very few bound AuNP probes and little to no enzymatic formation of diformazan precipitates or silver nanoparticles

  7. Forward-Masked Frequency Selectivity Improvements in Simulated and Actual Cochlear Implant Users Using a Preprocessing Algorithm.

    PubMed

    Langner, Florian; Jürgens, Tim

    2016-01-01

    Frequency selectivity can be quantified using masking paradigms, such as psychophysical tuning curves (PTCs). Normal-hearing (NH) listeners show sharp PTCs that are level- and frequency-dependent, whereas frequency selectivity is strongly reduced in cochlear implant (CI) users. This study aims at (a) assessing individual shapes of PTCs in CI users, (b) comparing these shapes to those of simulated CI listeners (NH listeners hearing through a CI simulation), and (c) increasing the sharpness of PTCs using a biologically inspired dynamic compression algorithm, BioAid, which has been shown to sharpen the PTC shape in hearing-impaired listeners. A three-alternative-forced-choice forward-masking technique was used to assess PTCs in 8 CI users (with their own speech processor) and 11 NH listeners (with and without listening through a vocoder to simulate electric hearing). CI users showed flat PTCs with large interindividual variability in shape, whereas simulated CI listeners had PTCs of the same average flatness, but more homogeneous shapes across listeners. The algorithm BioAid was used to process the stimuli before entering the CI users' speech processor or the vocoder simulation. This algorithm was able to partially restore frequency selectivity in both groups, particularly in seven out of eight CI users, meaning significantly sharper PTCs than in the unprocessed condition. The results indicate that algorithms can improve the large-scale sharpness of frequency selectivity in some CI users. This finding may be useful for the design of sound coding strategies particularly for situations in which high frequency selectivity is desired, such as for music perception. PMID:27604785

  8. Binaural release from masking with single- and multi-electrode stimulation in children with cochlear implants.

    PubMed

    Todd, Ann E; Goupell, Matthew J; Litovsky, Ruth Y

    2016-07-01

    Cochlear implants (CIs) provide children with access to speech information from a young age. Despite bilateral cochlear implantation becoming common, use of spatial cues in free field is smaller than in normal-hearing children. Clinically fit CIs are not synchronized across the ears; thus binaural experiments must utilize research processors that can control binaural cues with precision. Research to date has used single pairs of electrodes, which is insufficient for representing speech. Little is known about how children with bilateral CIs process binaural information with multi-electrode stimulation. Toward the goal of improving binaural unmasking of speech, this study evaluated binaural unmasking with multi- and single-electrode stimulation. Results showed that performance with multi-electrode stimulation was similar to the best performance with single-electrode stimulation. This was similar to the pattern of performance shown by normal-hearing adults when presented an acoustic CI simulation. Diotic and dichotic signal detection thresholds of the children with CIs were similar to those of normal-hearing children listening to a CI simulation. The magnitude of binaural unmasking was not related to whether the children with CIs had good interaural time difference sensitivity. Results support the potential for benefits from binaural hearing and speech unmasking in children with bilateral CIs. PMID:27475132

  9. Effect of pre-implanted helium on void swelling evolution in self-ion irradiated HT9

    NASA Astrophysics Data System (ADS)

    Getto, E.; Jiao, Z.; Monterrosa, A. M.; Sun, K.; Was, G. S.

    2015-07-01

    Void evolution in Fe++-irradiated ferritic-martensitic alloy HT9 was characterized in the temperature range of 400-480 °C between doses of 25 and 375 displacements per atom (dpa) with pre-implanted helium levels of 0-100 appm. A systematic study using depth profiling in cross-section samples was conducted to determine a valid region of analysis between 300 and 700 nm from the surface, which excluded effects due to the injected interstitial and the surface. Pre-implanted helium was found to promote void swelling at low doses by shortening the nucleation regime and to retard void growth at doses in the transient regime by enhancement of nucleation of small voids. Swelling was found to peak at a temperature of 460 °C. The primary effect of temperature was on the nucleation regime; nucleation regime was the shortest at 460 °C compared to that at 440 and 480 °C. The growth rate of voids was temperature-invariant. Steady state swelling was reached at 460 °C between 188 and 375 dpa at a rate of 0.02%/dpa.

  10. Technique for fabricating a custom gingival mask using a maxillary complete-arch implant-supported fixed interim prosthesis with an integrated verification cast.

    PubMed

    Esguerra, Roxanna J

    2016-01-01

    The custom gingival mask technique duplicates the tissue contours created by an implant-supported fixed interim prosthesis, which has been verified for satisfactory esthetics, phonetics, hygiene access, and patient comfort. This allows the dental laboratory technician to accurately duplicate the contours of the interim prosthesis in the definitive prosthesis. The technique described also incorporates a cast verification step to ensure the accurate, passive fit of the definitive prosthesis while eliminating the duplicate impression copings and implant replicas typically required for a verification cast. PMID:26384534

  11. Lattice modification in KTiOPO4 by hydrogen and helium sequentially implantation in submicrometer depth

    NASA Astrophysics Data System (ADS)

    Ma, Changdong; Lu, Fei; Xu, Bo; Fan, Ranran

    2016-05-01

    We investigated lattice modification and its physical mechanism in H and He co-implanted, z-cut potassium titanyl phosphate (KTiOPO4). The samples were implanted with 110 keV H and 190 keV He, both to a fluence of 4 × 1016 cm-2, at room temperature. Rutherford backscattering/channeling, high-resolution x-ray diffraction, and transmission electron microscopy were used to examine the implantation-induced structural changes and strain. Experimental and simulated x-ray diffraction results show that the strain in the implanted KTiOPO4 crystal is caused by interstitial atoms. The strain and stress are anisotropic and depend on the crystal's orientation. Transmission electron microscopy studies indicate that ion implantation produces many dislocations in the as-implanted samples. Annealing can induce ion aggregation to form nanobubbles, but plastic deformation and ion out-diffusion prevent the KTiOPO4 surface from blistering.

  12. Structural and optical properties of rare-earth doped lithium niobate waveguides formed by MeV helium ion implantation

    SciTech Connect

    Herreros, B.; Lifante, G.; Cusso, F.; Kling, A.; Soares, J.C.; Silva, M.F. da; Townsend, P.D.; Chandler, P.J.

    1996-12-31

    Results of investigations of optical waveguides formed by high energy helium implantation into lithium niobate codoped with 5 mol% MgO and 1 mol% Tm{sup 3+} or 1 mol% Er{sup 3+} are reported. A comparative study of structural and luminescence properties between implanted and untreated samples has been performed by means of Rutherford backscattering (RBS) combined with channeling and photoluminescence methods, respectively in order to investigate residual lattice damage and the incorporation of the optical active rare earths. For the case of Tm a full substitutional incorporation of the optical active rare earths. For the case of Tm a full substitutional incorporation on the lithium site and a high crystal quality in both bulk and implanted waveguide material has been found. For Er doped lithium niobate the channeling results show a fraction of Er randomly incorporated or forming precipitates and a deterioration of the waveguide`s lattice. The optical investigations show in both cases only a slight broadening of the emission lines of the rare earths in the waveguides compared to the bulk material.

  13. Simulation of nanostructure evolution under helium implantation in Fe-(2.5-12.5)at% Cr alloys at a temperature of 343 K

    NASA Astrophysics Data System (ADS)

    Gokhman, Aleksandr; Pecko, Stanislav; Slugeň, Vladimír

    2015-09-01

    Characterization of helium-implanted Fe-(2.5-12.5)at% Cr alloys with the flux of 7 × 10-6 dpa/s at a temperature of 343 K has been performed by means of cluster dynamics simulations. We have suggested a model for simulating an Fe-C-Cr system under helium implantation based on a selection of the latest data from atomistic studies and available experiments. Kinetics of carbon-vacancy and helium-vacancy complexes has been studied. Only one parameter is used to guarantee the best reproduction possible of experimental positron annihilation lifetime spectroscopy data for Fe-Cr alloys on dependences of vacancy cluster size on chromium content and irradiation dose via fitting. This is an effective binding energy of self-interstitial atoms to dislocation loops decorated by chromium atoms. It has a "snaky" dependence of chromium content with a minimum of about 9%Cr.

  14. Lattice swelling and modulus change in a helium-implanted tungsten alloy: X-ray micro-diffraction, surface acoustic wave measurements, and multiscale modelling

    SciTech Connect

    Hoffmann, F.; Nguyen-Manh, D.; Gilbert, M. R.; Beck, C. E.; Eliason, J. K.; Maznev, A. A.; Liu, W.; Armstrong, D. E.J.; Nelson, K. A.; Dudarev, S. L.

    2015-02-26

    Using X-ray micro-diffraction and surface acoustic wave spectroscopy, we measure lattice swelling and elastic modulus changes in aW-1% Re alloy after implantation with 3110 appm of helium. An observed lattice expansion of a fraction of a per cent gives rise to an order of magnitude larger reduction in the surface acoustic wave velocity. A multiscale model, combining elasticity and density functional theory, is applied to the interpretation of observations. The measured lattice swelling is consistent with the relaxation volume of self-interstitial and helium-filled vacancy defects that dominate the helium-implanted material microstructure. Larger scale atomistic simulations using an empirical potential confirm the findings of the elasticity and density functional theory model for swelling. The reduction of surface acoustic wave velocity predicted by density functional theory calculations agrees remarkably well with experimental observations.

  15. Precipitates and defects in silicon co-implanted with helium and oxygen

    NASA Astrophysics Data System (ADS)

    Li, B. S.; Zhang, C. H.; Zhang, H. H.; Zhang, Y.; Yang, Y. T.; Zhang, L. Q.

    2011-04-01

    Nano-bubbles or voids introduced by He implantation before the oxygen implantation collect oxygen and increase the oxygen content in the sample. Furthermore, nano-bubbles or voids can trap Si interstitials to decrease the dislocations at the edge of precipitates. The density and shape of precipitates formed in the initial stage of the separation-by-implanted-oxygen process are related to the size and density of He-induced vacancy-type defects (nano-bubbles and voids). A high density of nano-bubbles is more efficient in gettering than that of a low density of voids.

  16. Helium ion-implanted InGaAsP tunnel junction current blocking layers

    NASA Astrophysics Data System (ADS)

    Wang, Hongsheng; Forrest, Stephen R.

    2002-08-01

    We experimentally investigate and model He+-implanted InGaAsP tunnel junctions used for lateral current confinement in vertical-cavity surface-emitting lasers (VCSELs). Prior to implantation, a 56-mum-diameter tunnel junction exhibits a peak-to-valley ratio of 2.2 and a differential resistance of 27 Omega at -2 V. After implantation at a dose of 3.3 x1013 cm-2, the current under reverse bias reduces by a factor of >107. Placing tunnel junctions close to the laser active region does not degrade the gain in the quantum wells. With He+-implanted tunnel junctions, mirrorless test VCSEL structures up to 50 mum diameter have uniform current distribution across the entire light-emitting apertures.

  17. Irradiation creep and microstructural changes of ODS steels of different Cr-contents during helium implantation under stress

    NASA Astrophysics Data System (ADS)

    Chen, J.; Jung, P.; Henry, J.; de Carlan, Y.; Sauvage, T.; Duval, F.; Barthe, M. F.; Hoffelner, W.

    2013-06-01

    Irradiation creep and microstructural changes of two ferritic ODS steels with 12% and 14% Cr have been studied by homogeneously implantation with helium under uniaxial tensile stresses from 40 to 300 MPa. The maximum dose was about 1.2 dpa (5000 appm-He) with displacement damage rates of 1 × 10-5 dpa/s at a temperature of 300 °C. Irradiation creep compliances were measured to be 4.0 × 10-6 dpa-1 MPa-1 and 10 × 10-6 dpa-1 MPa-1 for 12 and 14Cr ODS, respectively. Subsequently, microstructural evolution was studied in detail by TEM observations, showing dislocation loops and bubbles distributed homogenously in the matrix. Some bubbles were attached to ODS particles. Finally, the effects of Cr content on irradiation creep and microstructural changes are discussed, including earlier results of a 19Cr ODS and a PM2000 ferritic steel. Irradiation creep rates of both 12Cr and 14Cr-ODS ferritic steels a temperature of 300 °C show linear stress dependence up to 300 MPa at. Irradiation creep rate per dose rate and stress at a temperature of 300 °C amounts to 4.0 × 10-6 dpa-1 MPa-1 and 10 × 10-6 dpa-1 MPa-1 for 12Cr- and 14Cr-ODS, respectively. Irradiation creep properties are remarkably insensitive to Cr content, grain size and dispersoid size. Dislocation loops and helium bubbles are distributed homogenously in the matrix. In the case of high density fine dispersoids, most bubbles are attached to ODS particles. This may suppress loop formation as well as growth of bubbles, thereby increasing the resistance of ODS ferritic steels against helium embrittlement.

  18. Two-wavelength Raman study of poly(ethylene terephthalate) surfaces modified by helium plasma-based ion implantation

    NASA Astrophysics Data System (ADS)

    Veres, M.; Tóth, A.; Mohai, M.; Bertóti, I.; Szépvölgyi, J.; Tóth, S.; Himics, L.; Koós, M.

    2012-12-01

    The surface of poly(ethylene terephthalate) (PET) was modified by helium plasma-based ion implantation (He PBII). The untreated and surface modified samples were characterised with optical absorption spectroscopy and two-wavelength micro-Raman spectroscopy excited with 488 nm and 785 nm light sources, allowing to examine the chemical bonding configuration of the surface layers on different depths and by selective enhancement of vibrations of different structural units. Upon treatment, simultaneously with the development of the broad D and G bands, a gradual decrease of the peaks corresponding to the Cdbnd C stretching and Cdbnd O stretching modes were observed with both excitations. Downshifting and broadening were detected for the Cdbnd C peak with both excitations and also for the Cdbnd O peak with the 488 nm excitation due to formation of condensed aromatic rings. Oppositely, upshifting was found with 785 nm excitation for the Cdbnd O peak and especially for its broad shoulder newly developed at the high wavenumber side. The latter feature was assigned to Cdbnd O groups attached to polymer chains without conjugation and the bands behaviour was interpreted by breaking of the Cdbnd C bonds of the polymer, leading to the formation of a crosslinked, disordered and stressed structure with still intact Cdbnd O groups, due to the increased nuclear damage at the end of the ion track.

  19. Formation of amorphous carbon on the surface of poly(ethylene terephthalate) by helium plasma based ion implantation

    NASA Astrophysics Data System (ADS)

    Tóth, A.; Veres, M.; Kereszturi, K.; Mohai, M.; Bertóti, I.; Szépvölgyi, J.

    2011-08-01

    The surface modification of poly(ethylene terephthalate) (PET) by helium plasma based ion implantation (He PBII) was studied. The effect of the main process parameters (acceleration voltage, fluence and fluence rate) on the alterations of the surface chemical composition and structure were investigated by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. According to SRIM calculations, at ion energies above 2 keV the stopping power of PET for He + ions is dominated by the electronic component and the contribution of the nuclear component is relatively small. Degradation of the ester group and carbonisation were observed by XPS due to elimination of O-rich fragments. The total C-content of the modified layer increased with the increase of fluence rate and acceleration voltage of particles, enabling the purposeful alteration of the surface composition. A strong broadening was detected in the Raman spectrum between 1000 and 1700 cm -1, testifying to the intense formation of amorphous carbon. The area ratio of the D (˜1410 cm -1) to G (˜1570 cm -1) band increased with the increase of particle fluence and the increase of acceleration voltage, offering the possibility of tailoring the chemical structure of the amorphous carbon layer created by the He PBII treatment.

  20. Helium plasma implantation on metals: Nanostructure formation and visible-light photocatalytic response

    SciTech Connect

    Kajita, Shin; Yoshida, Tomoko; Kitaoka, Daiki; Etoh, Reo; Yajima, Miyuki; Ohno, Noriyasu; Yoshida, Hisao; Yoshida, Naoaki; Terao, Yoshitaka

    2013-04-07

    It has been found recently that low-energy helium (He) plasma irradiation to tungsten (W) leads to the growth of W nanostructures on the surface. The process to grow the nanostructure is identified as a self-growth process of He bubbles and has a potential to open up a new plasma processing method. Here, we show that the metallic nanostructure formation process by the exposure to He plasma can occur in various metals such as, titanium, nickel, iron, and so on. When the irradiation conditions alter, the metallic cone arrays including nanobubbles inside are formed on the surface. Different from W cases, other processes than growth of fiberform structure, i.e., physical sputtering and the growth of large He bubbles, can be dominant on other metals during irradiation; various surface morphology changes can occur. The nanostructured W, part of which was oxidized, has revealed a significant photocatalytic activity under visible light (wavelength >700 nm) in decolorization of methylene blue without any co-catalyst.

  1. Trapping and surface permeation of deuterium in helium-implanted stainless steel

    NASA Astrophysics Data System (ADS)

    Myers, S. M.; Wampler, W. R.

    1982-12-01

    Austenitic stainless steel was ion-implanted with deuterium (D) and He and then heated, with the depth distribution of D being monitored via the nuclear reaction 2D( 3He, p) 4He. Analysis using diffusion theory indicated that D is bound to He-associated traps with an enthalpy of 0.42 ± 0.08 eV referenced to a solution site. The trapping entities are believed to be ~1 nm He bubbles observed by transmission electron microscopy, with D being bound to the bubble walls by a mechanism similar to chemisorption. Irradiation-defect traps, probably vacancies, exhibited a strength of only 0.22 ± 0.08 eV. Trapping behavior was essentially the same for types 304 and 310 stainless steel, indicating little dependence upon the stability of the austenitic (fcc) phase. The rate of D release at the surface was determined in the temperature range 425-575 K for two kinds of surface, one oxidized by electropolishing and air exposure, the other sputtered with Fe ions. Release was proportional to the square of solution concentration in both cases, but the recombination coefficient was ≳100 times greater for the sputtered surface.

  2. Effects of source-to-listener distance and masking on perception of cochlear implant processed speech in reverberant rooms

    PubMed Central

    Whitmal, Nathaniel A.; Poissant, Sarah F.

    2009-01-01

    Two experiments examined the effects of source-to-listener distance (SLD) on sentence recognition in simulations of cochlear implant usage in noisy, reverberant rooms. Experiment 1 tested sentence recognition for three locations in the reverberant field of a small classroom (volume=79.2 m3). Subjects listened to sentences mixed with speech-spectrum noise that were processed with simulated reverberation followed by either vocoding (6, 12, or 24 spectral channels) or no further processing. Results indicated that changes in SLD within a small room produced only minor changes in recognition performance, a finding likely related to the listener remaining in the reverberant field. Experiment 2 tested sentence recognition for a simulated six-channel implant in a larger classroom (volume=175.9 m3) with varying levels of reverberation that could place the three listening locations in either the direct or reverberant field of the room. Results indicated that reducing SLD did improve performance, particularly when direct sound dominated the signal, but did not completely eliminate the effects of reverberation. Scores for both experiments were predicted accurately from speech transmission index values that modeled the effects of SLD, reverberation, and noise in terms of their effects on modulations of the speech envelope. Such models may prove to be a useful predictive tool for evaluating the quality of listening environments for cochlear implant users. PMID:19894835

  3. Effects of helium ion implantation on the surface morphology of tungsten at high temperature for the first wall armor and divertor plates of fusion reactors

    NASA Astrophysics Data System (ADS)

    Zenobia, Samuel J.

    Three devices at the University of Wisconsin-Madison Inertial Electrostatic Confinement (UW IEC) laboratory were used to implant W and W alloys with helium ions at high temperatures. These devices were HOMER, HELIOS, and the Materials Irradiation Experiment (MITE-E). The research presented in this thesis will focus on the experiments carried out utilizing the MITE-E. Early UW work in HOMER and HELIOS on silicon carbide, carbon velvet, W-coated carbon velvet, fine-grain W, nano-grain W, W needles, and single- and polycrystalline W showed that these materials were not resistant to He+ implantation above ˜800 °C. Unalloyed W developed a "coral-like" surface morphology after He+ implantation, but appeared to be the most robust material investigated. The MITE-E used an ion gun technology to implant tungsten with 30 keV He+. Tungsten specimens were implanted at 900 °C to total average fluences of 6x1016 -- 6x1018 He +/cm2. Other specimens were implanted to a total average fluence of 5x1018 He+/cm2 at temperatures between 500 and 900 °C. Micrographs of the implanted W specimens revealed the development of three distinct surface morphologies. These morphologies are classified as "blistering", "pitting", and "orientated ridges". Preferential sputtering of the W by the energetic He+ appears to be responsible for pitting and orientated ridges which developed at high fluences (1019 He+/cm2) in the MITE-E. While the orientated ridges were the dominant morphology on the W surface above 700 °C, the pitting was prevalent below 700 °C. The blister morphology was observed at all of the examined temperatures at fluences ≥5x1017 He+/cm2 but disappeared above fluences of 1019 He+/cm 2. The "coral-like" surface morphology on W inherent to He + implantation experiments in HOMER and HELIOS developed from a combination of sources: multiangular ion incidence, ion energy spread (softening), and electron field emission from nano-scale surface features induced by He + implantation. The

  4. Suppression of repetitive surface exfoliation of Inconel 625 implanted sequentially with helium ions of different energies (20 100 keV)

    NASA Astrophysics Data System (ADS)

    Rao, A. S.; Whitton, J. L.; Kaminsky, M.

    Studies were conducted to explore if the surface exfoliation of Inconel 625, typical for 100 keV 4He + irradiations can be reduced by pre-irradiating the surfaces with helium ions sequentially over the energy range 20 to 50 keV. Polished, polycrystalline Inconel 625 samples were irradiated at 298K and 573K with 4He + at six different energies in the range from 20 to 50 keV in an order of decreasing energies. For each energy the dose was 0.13 C/cm 2, resulting in a total dose of 0.89 C/cm 2. Subsequently, these samples were implanted with 100 keV 4He + to a dose of 1.0 C/cm 2 or 2.0 C/cm 2. The results reveal that the low energy 4He + implants prior to the 100 keV 4He + implant reduce significantly the erosion yield typical for 100-keV 4He + irradiations alone. For 573K these reduced yields are still about one order of magnitude greater than physical sputtering yields.

  5. Experimental location of helium atoms in 6H-SiC crystal lattice after implantation and after annealing at 400 °C

    NASA Astrophysics Data System (ADS)

    Linez, F.; Garrido, F.; Erramli, H.; Sauvage, T.; Courtois, B.; Desgardin, P.; Barthe, M.-F.

    2015-04-01

    The question of the helium behavior in silicon carbide has been studied at the atomic scale by numerical simulations, but no experiment has been carried out to assess the results hitherto. This paper describes the first experiments allowing this comparison. 6H-SiC single crystals were implanted with 50-keV He ions at a fluence of 1015 He/cm2 at room temperature. The as-received and as-implanted samples were analyzed by RBS and NRA in channeling mode along the main crystallographic planes and across three main axes. The measurements have shown that a portion of the He is located in the interstitial tetrahedral sites as predicted by the numerical simulations. The same measurements were performed on an implanted sample subsequently annealed at 400 °C under Ar atmosphere. They have shown that the quantity of He detected in interstitial tetrahedral sites TSi and TC has not significantly changed whereas that of He detected in the main crystallographic plane and in the main axis has increased. This increase is likely caused by He atoms migration at 400 °C toward interstitial positions located inside vacancies such as VSi and VSiVC. In parallel a partial recovery of the Si and C sublattices has been observed.

  6. Clay Mask Workshop

    ERIC Educational Resources Information Center

    Gamble, David L.

    2012-01-01

    Masks can represent so many things, such as emotions (happy, sad, fearful) and power. The familiar "comedy and tragedy" masks, derived from ancient Greek theater, are just one example from mask history. Death masks from the ancient Egyptians influenced the ancient Romans into creating similar masks for their departed. Masks can represent many…

  7. Quantitation of maxillary remodeling. 2. Masking of remodeling effects when an "anatomical" method of superimposition is used in the absence of metallic implants.

    PubMed

    Baumrind, S; Korn, E L; Ben-Bassat, Y; West, E E

    1987-06-01

    We report the results of a study aimed at quantifying the differences in the perceived pattern of maxillary remodeling that are observed when different methods are used to superimpose maxillary images in roentgenographic cephalometrics. In a previous article, we reported cumulative changes in the positions of anterior nasal spine (ANS), posterior nasal spine (PNS), and Point A for a sample of 31 subjects with maxillary metallic implants. Measurements had been made on lateral cephalograms taken at annual intervals relative to superimposition on the implants. In the present article, we quantify the differences in the perceived displacement of the same landmarks in the same sample when a standard "anatomical best bit" rule was used in lieu of superimposition on the implants. The anatomical best fit superimposition as herein defined was found in this sample to lose important information on the downward remodeling of the superior surface of the maxilla that had been detected when the implant superimposition was used. In fact, we observed a small artifactual upward displacement of the ANS-PNS line. In the anteroposterior direction, the tendency toward backward displacement of skeletal landmarks through time that had been detected with the implant superimposition was replaced by a small forward displacement of ANS and Point A together with reduced backward displacement of PNS. To the extent that the implant superimposition is to be considered the true and correct one, the anatomical best fit superimposition appears to understate the true downward remodeling of the palate by an average of about 0.3 and 0.4 mm per year, although this value differs at different ages and timepoints. The anatomical best fit superimposition also misses entirely the small mean tendency toward backward remodeling that was observed when the implant superimposition was used. In situations in which there are no implants, clinicians and research workers must necessarily continue to use anatomically

  8. Smoke Mask

    NASA Technical Reports Server (NTRS)

    2003-01-01

    Smoke inhalation injury from the noxious products of fire combustion accounts for as much as 80 percent of fire-related deaths in the United States. Many of these deaths are preventable. Smoke Mask, Inc. (SMI), of Myrtle Beach, South Carolina, is working to decrease these casualties with its line of life safety devices. The SMI personal escape hood and the Guardian Filtration System provide respiratory protection that enables people to escape from hazardous and unsafe conditions. The breathing filter technology utilized in the products is specifically designed to supply breathable air for 20 minutes. In emergencies, 20 minutes can mean the difference between life and death.

  9. Generation of ensembles of individually resolvable nitrogen vacancies using nanometer-scale apertures in ultrahigh-aspect ratio planar implantation masks.

    PubMed

    Bayn, Igal; Chen, Edward H; Trusheim, Matthew E; Li, Luozhou; Schröder, Tim; Gaathon, Ophir; Lu, Ming; Stein, Aaron; Liu, Mingzhao; Kisslinger, Kim; Clevenson, Hannah; Englund, Dirk

    2015-03-11

    A central challenge in developing magnetically coupled quantum registers in diamond is the fabrication of nitrogen vacancy (NV) centers with localization below ∼20 nm to enable fast dipolar interaction compared to the NV decoherence rate. Here, we demonstrate the targeted, high throughput formation of NV centers using masks with a thickness of 270 nm and feature sizes down to ∼1 nm. Super-resolution imaging resolves NVs with a full-width maximum distribution of 26 ± 7 nm and a distribution of NV-NV separations of 16 ± 5 nm. PMID:25621759

  10. Mask process simulation for mask quality improvement

    NASA Astrophysics Data System (ADS)

    Takahashi, Nobuyasu; Goto, So; Tsunoda, Dai; Shin, So-Eun; Lee, Sukho; Shon, Jungwook; Park, Jisoong

    2015-10-01

    Demand for mask process correction (MPC) is growing facing the 14nm era. We have developed model based MPC and can generate mask contours by using this mask process model. This mask process model consists of EB (development) and etch, which employs a threshold (level set) model and a variable bias model respectively. The model calibration tool accepts both CD measurement results and SEM images. The simulation can generate mask image (contour), runs with distributed computing resources, and has scalable performance. The contour simulation shows the accuracy of the MPC correction visually and provides comprehensive information about hot spots in mask fabrication. Additionally, it is possible to improve lithography simulation quality by providing a simulated mask contour. In this paper, accuracy and computational performance of mask process simulation are shown. The focus is on the difference between the calibration methods using CDs or images.

  11. Masks and Other Disguises.

    ERIC Educational Resources Information Center

    Ploghoft, Debra

    Instructions for making simple masks are provided in this guide for teachers of elementary children. Directions with illustrations are given for constructing masks from paper plates, construction paper, plastic milk jugs, and papier-mache. Ideas include a clown mask, a flower mask, a top hat, a paper crown, and "Groucho" glasses. Types of masks…

  12. Irradiation hardening of Fe-9Cr-based alloys and ODS Eurofer: Effect of helium implantation and iron-ion irradiation at 300 °C including sequence effects

    NASA Astrophysics Data System (ADS)

    Heintze, C.; Bergner, F.; Hernández-Mayoral, M.; Kögler, R.; Müller, G.; Ulbricht, A.

    2016-03-01

    Single-beam, dual-beam and sequential iron- and/or helium-ion irradiations are widely accepted to emulate more application-relevant but hardly accessible irradiation conditions of generation-IV fission and fusion candidate materials for certain purposes such as material pre-selection, identification of basic mechanisms or model calibration. However, systematic investigations of sequence effects capable to critically question individual approaches are largely missing. In the present study, sequence effects of iron-ion irradiations at 300 °C up to 5 dpa and helium implantations up to 100 appm He are investigated by means of post-irradiation nanoindentation of an Fe9%Cr model alloy, ferritic/martensitic 9%Cr steels T91 and Eurofer97 and oxide dispersion strengthened (ODS) Eurofer. Different types of sequence effects, both synergistic and antagonistic, are identified and tentative interpretations are suggested. It is found that different accelerated irradiation approaches have a great impact on the mechanical hardening. This stresses the importance of experimental design in attempts to emulate in-reactor conditions.

  13. Shuttle mask floorplanning

    NASA Astrophysics Data System (ADS)

    Xu, Gang; Tian, Ruiqi; Wong, Martin D.; Reich, Alfred J.

    2003-12-01

    A shuttle mask has different chips on the same mask. The chips are not electrically connected. Alliance and foundry customers can utilize shuttle masks to share the rising cost of mask and wafer manufacturing. This paper studies the shuttle mask floorplan problem, which is formulated as a rectangle-packing problem with constraints of final die sawing strategy and die-to-die mask inspection. For our formulation, we offer a "merging" method that reduces the problem to an unconstrained slicing floorplan problem. Excellent results are obtained from the experiment with real industry data. We also study a "general" method and discuss the reason why it does not work very well.

  14. Keeping African Masks Real

    ERIC Educational Resources Information Center

    Waddington, Susan

    2012-01-01

    Art is a good place to learn about our multicultural planet, and African masks are prized throughout the world as powerfully expressive artistic images. Unfortunately, multicultural education, especially for young children, can perpetuate stereotypes. Masks taken out of context lose their meaning and the term "African masks" suggests that there is…

  15. Mask degradation monitoring with aerial mask inspector

    NASA Astrophysics Data System (ADS)

    Tseng, Wen-Jui; Fu, Yung-Ying; Lu, Shih-Ping; Jiang, Ming-Sian; Lin, Jeffrey; Wu, Clare; Lifschitz, Sivan; Tam, Aviram

    2013-06-01

    As design rule continues to shrink, microlithography is becoming more challenging and the photomasks need to comply with high scanner laser energy, low CDU, and ever more aggressive RETs. This give rise to numerous challenges in the semiconductor wafer fabrication plants. Some of these challenges being contamination (mainly haze and particles), mask pattern degradation (MoSi oxidation, chrome migration, etc.) and pellicle degradation. Fabs are constantly working to establish an efficient methodology to manage these challenges mainly using mask inspection, wafer inspection, SEM review and CD SEMs. Aerial technology offers a unique opportunity to address the above mask related challenges using one tool. The Applied Materials Aera3TM system has the inherent ability to inspect for defects (haze, particles, etc.), and track mask degradation (e.g. CDU). This paper focuses on haze monitoring, which is still a significant challenge in semiconductor manufacturing, and mask degradation effects that are starting to emerge as the next challenge for high volume semiconductor manufacturers. The paper describes Aerial inspector (Aera3) early haze methodology and mask degradation tracking related to high volume manufacturing. These will be demonstrated on memory products. At the end of the paper we take a brief look on subsequent work currently conducted on the more general issue of photo mask degradation monitoring by means of an Aerial inspector.

  16. Mask industry assessment: 2004

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert V.; Hector, Scott D.

    2004-12-01

    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of equipment for mask fabrication. This year's assessment is the third in the current series of annual reports and is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. This report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results may be used to guide future investments on critical path issues. This year's survey builds upon the 2003 survey to provide an ongoing database using the same questions as a baseline with only a few minor changes or additions. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services. Within each category are a many questions that create a detailed profile of both the business and technical status of the mask industry. This assessment includes inputs from ten major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market.

  17. 2013 mask industry survey

    NASA Astrophysics Data System (ADS)

    Malloy, Matt

    2013-09-01

    A comprehensive survey was sent to merchant and captive mask shops to gather information about the mask industry as an objective assessment of its overall condition. 2013 marks the 12th consecutive year for this process. Historical topics including general mask profile, mask processing, data and write time, yield and yield loss, delivery times, maintenance, and returns were included and new topics were added. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the mask industry. While each year's survey includes minor updates based on feedback from past years and the need to collect additional data on key topics, the bulk of the survey and reporting structure have remained relatively constant. A series of improvements is being phased in beginning in 2013 to add value to a wider audience, while at the same time retaining the historical content required for trend analyses of the traditional metrics. Additions in 2013 include topics such as top challenges, future concerns, and additional details in key aspects of mask masking, such as the number of masks per mask set per ground rule, minimum mask resolution shipped, and yield by ground rule. These expansions beyond the historical topics are aimed at identifying common issues, gaps, and needs. They will also provide a better understanding of real-life mask requirements and capabilities for comparison to the International Technology Roadmap for Semiconductors (ITRS).

  18. The use of ion accelerators and synchrotron radiation to study the interactions of helium with metals

    SciTech Connect

    Donnelly, S.E.; Gilles, J.M.; Lucas, A.A.; Rife, J.C.

    1981-04-01

    A technique is described which examines the properties of helium trapped in bubbles in implanted metals. Helium implanted materials are characterized using resonant elastic proton backscattering and Transmission Electron Microscopy. Spectroscopic measurements using synchrotron radiation in the far vacuum ultraviolet are then performed to examine the density sensitive optical absorption resulting from the 1S - 2P transition in the implanted helium. Experimental data for helium implanted aluminum thin films are presented which indicate atomic densities in small (50A diameter) bubbles of the order of 10/sup 23/ atoms cm/sup -3/.

  19. Mask industry assessment: 2003

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2003-12-01

    Microelectronics industry leaders routinely name mask technology and mask supply issues of cost and cycle time as top issues of concern. A survey was initiated in 2002 with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition.1 This paper presents the results of the second annual survey which is an enhanced version of the inaugural survey building upon its strengths and improving the weak points. The original survey was designed with the input of member company mask technologists, merchant mask suppliers, and industry equipment makers. The assessment is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the critical mask industry. An objective is to create a valuable reference to identify strengths and opportunities and to guide investments on critical-path issues. As subsequent years are added, historical profiles can also be created. This assessment includes inputs from ten major global merchant and captive mask manufacturers representing approximately 80% of the global mask market (using revenue as the measure) and making this the most comprehensive mask industry survey ever. The participating companies are: Compugraphics, Dai Nippon Printing, Dupont Photomask, Hoya, IBM, Infineon, Intel, Taiwan Mask Company, Toppan, and TSMC. Questions are grouped into five categories: General Business Profile Information; Data Processing; Yields and Yield loss Mechanisms; Delivery Time; and Returns and Services. Within each category are a multitude of questions that create a detailed profile of both the business and technical status of the mask industry.

  20. Helium Migration Mechanisms in Polycrystalline Uranium Dioxide

    SciTech Connect

    Martin, Guillaume; Desgardin, Pierre; Sauvage, Thierry; Barthe, Marie-France; Garcia, Philippe; Carlot, Gaelle

    2007-07-01

    This study aims at identifying the release mechanisms of helium in uranium dioxide. Two sets of polycrystalline UO{sub 2} sintered samples presenting different microstructures were implanted with {sup 3}He ions at concentrations in the region of 0.1 at.%. Changes in helium concentrations were monitored using two Nuclear Reaction Analysis (NRA) techniques based on the {sup 3}He(d,{alpha}){sup 1}H reaction. {sup 3}He release is measured in-situ during sample annealing at temperatures ranging between 700 deg. C and 1000 deg. C. Accurate helium depth profiles are generated after each annealing stage. Results that provide data for further understanding helium release mechanisms are discussed. It is found that helium diffusion appears to be enhanced above 900 deg. C in the vicinity of grain boundaries possibly as a result of the presence of defects. (authors)

  1. Object Substitution Masking: When Does Mask Preview Work?

    ERIC Educational Resources Information Center

    Lim, Stephen Wee Hun; Chua, Fook K.

    2008-01-01

    When a target is enclosed by a 4-dot mask that persists after the target disappears, target identification is worse than it is when the mask terminates with the target. This masking effect is attributed to object substitution masking (OSM). Previewing the mask, however, attenuates OSM. This study investigated specific conditions under which mask…

  2. Mask industry assessment: 2005

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Hector, Scott

    2005-11-01

    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of equipment for mask fabrication. This year's assessment is the fourth in the current series of annual reports and is intended to be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. This report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results may be used to guide future investments on critical path issues. This year's survey contains all of the 2004 survey questions to provide an ongoing database. Additional questions were added to the survey covering operating cost factors and equipment utilization. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services, operating cost factors and equipment utilization. Within each category are a many questions that create a detailed profile of both the business and technical status of the mask industry. This assessment includes inputs from eight major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market. This participation rate is reduced by one captive from 2004. Note: Toppan, DuPont Photomasks Inc and AMTC (new) were consolidated into one input therefore the 2004 and 2005 surveys are basically equivalent.

  3. Mask industry assessment: 2006

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Marmillion, Patricia

    2006-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the fifth in the current series of annual reports. With continued industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 survey. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns and Services, Operating Cost Factors, and Equipment Utilization. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  4. Mask industry assessment: 2009

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Yun, Henry

    2009-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by David Powell Consulting to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the eighth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 through 2008 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry. This in combination with the past surveys represents a comprehensive view of changes in the industry.

  5. Mask industry assessment: 2008

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Yun, Henry

    2008-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by David Powell Consulting to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the seventh in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 through 2007 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  6. Mask Industry Assessment: 2007

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Marmillion, Patricia; Hughes, Greg

    2007-10-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the sixth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey is basically the same as the 2005 and 2006 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns and Services, Operating Cost Factors, and Equipment Utilization. Within each category is a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  7. Mask industry assessment: 2002

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2002-12-01

    Microelectronics industry leaders routinely name mask technology and mask supply issues of cost and cycle time as top issues of concern. A survey was created with support from International SEMATECH (ISMT) and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of member company mask technologists, merchant mask suppliers, and industry equipment makers. This assessment can be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of our critical mask industry. It should serve as a valuable reference to identify strengths and opportunities and to guide investments on critical-path issues. Questions are grouped into five categories: General Business Profile Information; Data Processing; Yields and Yield loss Mechanisms; Delivery Time; and Returns and Services. Within each category are a multitude of questions that create a detailed profile of both the business and technical status of the critical mask industry.

  8. Mask and pattern characteristics

    NASA Technical Reports Server (NTRS)

    Routh, D. E.

    1972-01-01

    The use of the mask and pattern facility to include information on equipment accuracy, limitations, and pattern making capabilities is discussed. An insight is provided into potential areas of pattern applications, the sequence of mask making, as well as possible inputs and outputs available to the user.

  9. Mini Metal Masks.

    ERIC Educational Resources Information Center

    Henn, Cynthia

    2003-01-01

    Describes an art project used with kindergarten and first-grade students that focused on traditional African masks as part of a unit on the culture of West Africa. Discusses how the students created their clay masks. Includes lists of learning objectives and art materials. (CMK)

  10. Enhancement in Informational Masking

    ERIC Educational Resources Information Center

    Cao, Xiang; Richards, Virginia M.

    2012-01-01

    Purpose: The ability to detect a tone added to a random masker improves when a preview of the masker is provided. In 2 experiments, the authors explored the role that perceptual organization plays in this release from masking. Method: Detection thresholds were measured in informational masking studies. The maskers were drawn at random prior to…

  11. Lightweight Face Mask

    NASA Technical Reports Server (NTRS)

    Cason, W. E. I.; Baucom, R. M.; Evans, R. C.

    1982-01-01

    Lightweight face mask originally developed to protect epileptic patients during seizures could have many other medical and nonmedical applications such as muscular distrophy patients, football linesmen and riot-control police. Masks are extremely lightweight, the lightest of the configurations weighing only 136 grams.

  12. Large area self-assembled masking for photonic applications

    NASA Astrophysics Data System (ADS)

    Nagy, N.; Pap, A. E.; Horváth, E.; Volk, J.; Bársony, I.; Deák, A.; Hórvölgyi, Z.

    2006-08-01

    Ordered porous structures for photonic application were fabricated on p- and n-type silicon by means of masking against ion implantation with Langmuir-Blodgett (LB) films. LB films from Stöber silica spheres [J. Colloid Interface Sci. 26, 62 (1968)] of 350nm diameter were applied in the boron and phosphorus ion-implantation step, thereby offering a laterally periodic doping pattern. Ordered porous silicon structures were obtained after performing an anodic etch and were then removed by alkaline etching resulting in the required two-dimensional photonic arrangement. The LB silica masks and the resulting silicon structures were studied by field emission scanning electron microscope analysis.

  13. 2012 Mask Industry Survey

    NASA Astrophysics Data System (ADS)

    Malloy, Matt; Litt, Lloyd C.

    2012-11-01

    A survey supported by SEMATECH and administered by David Powell Consulting was sent to semiconductor industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. 2012 marks the 11th consecutive year for the mask industry survey. This year's survey and reporting structure are similar to those of the previous years with minor modifications based on feedback from past years and the need to collect additional data on key topics. Categories include general mask information, mask processing, data and write time, yield and yield loss, delivery times, and maintenance and returns. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the mask industry. Results, initial observations, and key comparisons between the 2011 and 2012 survey responses are shown here, including multiple indications of a shift towards the manufacturing of higher end photomasks.

  14. Efficient oxygen gettering in Si by coimplantation of hydrogen and helium

    SciTech Connect

    Ou Xin; Koegler, Reinhard; Muecklich, Arndt; Skorupa, Wolfgang; Moeller, Wolfhard; Wang Xi; Gerlach, Juergen W.; Rauschenbach, Bernd

    2008-10-20

    Hydrogen preimplantation performed in addition to helium implantation efficiently shrinks the width of the gettering layer in Si and increases the empty volume fraction as well as the internal surface area per unit volume. The gettering efficiency for oxygen is significantly enhanced compared to the single helium implantation, and the helium implantation dose can be strongly reduced. The gas-filled bubble layer induced by the coimplantation of hydrogen and helium has the highest gettering efficiency for the oxygen accumulation. Direct evidence for oxygen gettering at the internal wall of the cavity is demonstrated by cross-sectional transmission electron microscopy.

  15. Protective Face Mask

    NASA Technical Reports Server (NTRS)

    1981-01-01

    Mask to protect the physically impaired from injuries to the face and head has been developed by Langley Research Center. It is made of composite materials, usually graphite or boron fibers woven into a matrix. Weighs less than three ounces.

  16. Masked Photocathode for Photoinjector

    SciTech Connect

    Qiang, Ji

    2010-01-21

    In this research note, we propose a scheme to insert a photocathode inside a photoinjector for generating high brightness electron beam. Instead of mounting the photocathode onto the electrode, a masked electrode with small hole is used to shield the photocathode from the accelerating vacuum chamber. Using such a masked photocathode will make the replacement of photocathode material very simple by rotating the photocathode behind the mask into the hole. This will significantly increase the usage lifetime of a photocathode. Furthermore, this also helps reduce the dark current or secondary electron emission from the photocathode. The hole on the mask also provides a transverse cut-off to the Gaussian laser profile which can be beneficial from the beam dynamics point of view.

  17. EUVL Mask Blank Repair

    SciTech Connect

    Barty, A; Mirkarimi, P; Stearns, D G; Sweeney, D; Chapman, H N; Clift, M; Hector, S; Yi, M

    2002-05-22

    EUV mask blanks are fabricated by depositing a reflective Mo/Si multilayer film onto super-polished substrates. Small defects in this thin film coating can significantly alter the reflected field and introduce defects in the printed image. Ideally one would want to produce defect-free mask blanks; however, this may be very difficult to achieve in practice. One practical way to increase the yield of mask blanks is to effectively repair multilayer defects, and to this effect they present two complementary defect repair strategies for use on multilayer-coated EUVL mask blanks. A defect is any area on the mask which causes unwanted variations in EUV dose in the aerial image obtained in a printing tool, and defect repair is correspondingly defined as any strategy that renders a defect unprintable during exposure. The term defect mitigation can be adopted to describe any strategy which renders a critical defect non-critical when printed, and in this regard a non-critical defect is one that does not adversely affect device function. Defects in the patterned absorber layer consist of regions where metal, typically chrome, is unintentionally added or removed from the pattern leading to errors in the reflected field. There currently exists a mature technology based on ion beam milling and ion beam assisted deposition for repairing defects in the absorber layer of transmission lithography masks, and it is reasonable to expect that this technology will be extended to the repair of absorber defects in EUVL masks. However, techniques designed for the repair of absorber layers can not be directly applied to the repair of defects in the mask blank, and in particular the multilayer film. In this paper they present for the first time a new technique for the repair of amplitude defects as well as recent results on the repair of phase defects.

  18. Helium solubility in SON68 nuclear waste glass

    SciTech Connect

    Fares, Toby; Peuget, Sylvain; Bouty, Olivier; Broudic, Veronique; Maugeri, Emilio; Bes, Rene; Jegou, Christophe; Chamssedine, Fadel; Sauvage, Thierry; Deschanels, Xavier

    2012-12-15

    Helium behavior in a sodium borosilicate glass (SON68) dedicated to the immobilization of high-level nuclear waste is examined. Two experimental approaches on nonradioactive glass specimens are implemented: pressurized helium infusion experiments and {sup 3}He ion implantation experiments. The temperature variation of helium solubility in SON68 glass was determined and analyzed with the harmonic oscillator model to determine values of the energy of interaction E(0) at the host sites (about -4000 J/mol), the vibration frequency (about 1.7 x 10{sup 11} s{sup -1}), and the density of solubility sites (2.2 x 10{sup 21} sites cm{sup -3}). The implantation experiments show that a non diffusive transport phenomenon (i.e., athermal diffusion) is involved in the material when the helium concentration exceeds 2.3 x 10{sup 21} He cm{sup -3}, and thus probably as soon as it exceeds the density of solubility sites accessible to helium in the glass. We propose that this transport mechanism could be associated with the relaxation of the stress gradient induced by the implanted helium profile, which is favored by the glass damage. Microstructural characterization by TEM and ESEM of glass specimens implanted with high helium concentrations showed a homogeneous microstructure free of bubbles, pores, or cracking at a scale of 10 nm. (authors)

  19. Mask Industry Assessment: 2010

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Chan, David Y.

    2010-09-01

    A survey created supported by SEMATECH and administered by David Powell Consulting was sent to microelectronics industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the ninth in the current series of annual reports. With ongoing industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. It will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey was basically the same as the 2005 through 2009 surveys. Questions are grouped into categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the critical mask industry. This profile combined with the responses to past surveys represents a comprehensive view of changes in the industry.

  20. Mask Industry Assessment: 2011

    NASA Astrophysics Data System (ADS)

    Chan, Y. David

    2011-11-01

    A survey supported by SEMATECH and administered by David Powell Consulting was sent to microelectronics industry leaders to gather information about the mask industry as an objective assessment of its overall condition. The survey was designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the tenth in the current series of annual reports. With ongoing industry support, the report has been used as one of the baselines to gain perspective on the technical and business status of the mask and microelectronics industries. It continues to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments pertaining to critical path issues. This year's survey was essentially the same as the 2005 through 2010 surveys. Questions are grouped into following categories: General Business Profile Information, Data Processing, Yields and Yield Loss Mechanisms, Delivery Times, Returns, and Services. Within each category are multiple questions that result in a detailed profile of both the business and technical status of the critical mask industry. This profile combined with the responses to past surveys represents a comprehensive view of changes in the industry.

  1. New mask technology challenges

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2001-09-01

    Mask technology development has accelerated dramatically in recent years from the glacial pace of the last three decades to the rapid and sometimes simultaneous introductions of new wavelengths and mask-based resolution enhancement techniques. The nature of the semiconductor business has also become one driven by time-to-market as an overwhelming factor in capturing market share and profit. These are among the factors that have created enormous stress on the mask industry to produce masks with enhanced capabilities, such as phase-shifting attenuators, sub-resolution assist bars, and optical proximity correction (OPC) features, while maintaining or reducing cost and cycle time. The mask can no longer be considered a commodity item that is purchased form the lowest-cost supplier. Instead, it must now be promoted as an integral part of the technical and business case for a total lithographic solution. Improving partnership between designer, mask-maker, and wafer lithographer will be the harbinger of success in finding a profitable balance of capability, cost, and cycle time. Likewise for equipment infrastructure development, stronger partnership on the international level is necessary to control development cost and mitigate schedule and technical risks.

  2. Masks: The Artist in Me

    ERIC Educational Resources Information Center

    Skophammer, Karen

    2009-01-01

    Whether masks are made from cardboard, papier-mache, metal, wood, leather, fabric, clay or any combination of these materials, they bring out the artist in people. Young children like to wear masks when they play to pretend they were another person or animal. Masks let them fantasize and be creative. The author's students made masks representing…

  3. In situ probing of helium desorption from individual nanobubbles under electron irradiation

    SciTech Connect

    David, M.-L.; Pailloux, F.; Mauchamp, V.; Pizzagalli, L.

    2011-04-25

    The understanding of the mechanisms of helium bubble formation and evolution in materials requires the quantitative determination of several key quantities such as the helium density in the bubbles. Helium nanobubbles of about 16 nm in diameter were created in silicon by helium implantation at high fluence and subsequent annealing. Individual nanobubbles were analyzed by spatially resolved Electron Energy-loss Spectroscopy (EELS). We report on the in situ probing of helium desorption from the nanobubbles under electron irradiation. This opens new perspectives for a more accurate determination of the helium density through spatially resolved EELS.

  4. Overview of Mask Metrology

    NASA Astrophysics Data System (ADS)

    Rice, Bryan J.; Jindal, Vibhu; Lin, C. C.; Harris-Jones, Jenah; Kwon, Hyuk Joo; Ma, Hsing-Chien; Goldstein, Michael; Chan, Yau-Wai; Goodwin, Frank

    2011-11-01

    Extreme ultraviolet (EUV) lithography is the successor to optical lithography and will enable advanced patterning in semiconductor manufacturing processes down to the 8 nm half pitch technology node and beyond. However, before EUV can successfully be inserted into high volume manufacturing a few challenges must be overcome. Central among these remaining challenges is the requirement to produce "defect free" EUV masks. Mask blank defects have been one of the top challenges in the commercialization of extreme ultraviolet (EUV) lithography. To determine defect sources and devise mitigation solutions, detailed characterization of defects is critical. However, small defects pose challenges in metrology scale-up. SEMATECH has a comprehensive metrology strategy to address any defect larger than a 20 nm core size to obtain solutions for defect-free EUV mask blanks. SEMATECH's Mask Blank Development Center has been working since 2003 to develop the technology to support defect free EUV mask blanks. Since 2003, EUV mask blank defects have been reduced from 10000 of size greater than 100 nm to about a few tens at size 70 nm. Unfortunately, today's state of the art defect levels are still about 10 to 100 times higher than needed. Closing this gap requires progress in the various processes associated with glass substrate creation and multilayer deposition. That process development improvement in turn relies upon the availability of metrology equipment that can resolve and chemically characterize defects as small as 30 nm. The current defect reduction efforts at SEMATECH have intensively included a focus on inspection and characterization. The facility boasts nearly 100M of metrology hardware, including an FEI Titan TEM, Lasertec M1350 and M7360 tools, an actinic inspection tool, AFM, SPM, and scanning auger capabilities. The newly established Auger tool at SEMATECH can run a standard 6-inch mask blank and is already providing important information on sub-100 nm defects on EUV

  5. Spatial release from masking with noise-vocoded speech

    PubMed Central

    Freyman, Richard L.; Balakrishnan, Uma; Helfer, Karen S.

    2008-01-01

    This study investigated how confusability between target and masking utterances affects the masking release achieved through spatial separation. Important distinguishing characteristics between competing voices were removed by processing speech with six-channel envelope vocoding, which simulates some aspects of listening with a cochlear implant. In the first experiment, vocoded target nonsense sentences were presented against two-talker vocoded maskers in conditions that provide different spatial impressions but not reliable cues that lead to traditional release from masking. Surprisingly, no benefit of spatial separation was found. The absence of spatial release was hypothesized to be the result of the highly positive target-to-masker ratios necessary to understand vocoded speech, which may have been sufficient to reduce confusability. In experiment 2, words excised from the vocoded nonsense sentences were presented against the same vocoded two-talker masker in a four-alternative forced-choice detection paradigm where threshold performance was achieved at negative target-to-masker ratios. Here, the spatial release from masking was more than 20 dB. The results suggest the importance of signal-to-noise ratio in the observation of “informational” masking and indicate that careful attention should be paid to this type of masking as implant processing improves and listeners begin to achieve success in poorer listening environments. PMID:19045654

  6. Orion Emergency Mask Approach

    NASA Technical Reports Server (NTRS)

    Tuan, George C.; Graf, John C.

    2008-01-01

    Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction temperature and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

  7. Orion Emergency Mask Approach

    NASA Technical Reports Server (NTRS)

    Tuan, George C.; Graf, John C.

    2009-01-01

    Emergency mask approach on Orion poses a challenge to the traditional Shuttle or Station approaches. Currently, in the case of a fire or toxic spill event, the crew utilizes open loop oxygen masks that provide the crew with oxygen to breath, but also dumps the exhaled oxygen into the cabin. For Orion, with a small cabin volume, the extra oxygen will exceed the flammability limit within a short period of time, unless a nitrogen purge is also provided. Another approach to a fire or toxic spill event is the use of a filtering emergency masks. These masks utilize some form of chemical beds to scrub the air clean of toxic providing the crew safe breathing air for a period without elevating the oxygen level in the cabin. Using the masks and a form of smoke-eater filter, it may be possible to clean the cabin completely or to a level for safe transition to a space suit to perform a cabin purge. Issues with filters in the past have been the reaction time, breakthroughs, and high breathing resistance. Development in a new form of chemical filters has shown promise to make the filtering approach feasible.

  8. Peculiarities of helium bubble formation and helium behavior in vanadium alloys of different chemical composition

    NASA Astrophysics Data System (ADS)

    Staltsov, М. S.; Chernov, I. I.; Kalin, B. A.; Oo, Kyi Zin; Polyansky, A. A.; Staltsova, O. S.; Aung, Kyaw Zaw; Chernov, V. M.; Potapenko, M. M.

    2015-06-01

    The influence of alloying of vanadium by Ti and Fe on helium bubble formation, gaseous swelling and helium release peculiarities is investigated by means of transmission electron microscopy and helium thermal desorption spectrometry (HTDS). The samples were irradiated by 40 keV He+ ions up to a fluence of 5 ṡ 1020 m-2 at 293 and 923 K. It is found that large faceted pores/bubbles are formed in pure vanadium and it has the highest gaseous swelling. Alloying by any used quantity of Ti (from 0.1 up to 10 wt.%) or Fe (from 1 up to 10 wt.%) essentially decreases the helium swelling. The effect of alloying of vanadium by Ti on the bubble sizes and the helium swelling is nonmonotonic. The density of bubbles increases significantly and their sizes and swelling grow monotonically with increasing the Fe content in vanadium. With low-temperature helium implantation, alloying of V by Ti shifts the HTDS peaks to higher temperatures and the temperatures of peaks are decreased with increasing the Fe concentration. A significant portion of the helium releases in a high-temperature area beyond the main peak temperatures in the HTDS spectra. It is assumed that this is caused by formation of helium bubbles on the surfaces of incoherent particles of secondary phases (oxides, nitrides), having high binding energies with these particles.

  9. Optical Forces on Metastable Helium

    NASA Astrophysics Data System (ADS)

    Corder, Christopher Scott

    Optical forces using lasers allow precise control over the motion of atoms. The bichromatic optical force (BF) is unique in its large magnitude and velocity range, arising from the absorption and stimulated emission processes. These properties were used to transversely collimate a beam of metastable helium (He*) using the 23S - 23P transition. The collimation created a very bright beam of He*, allowing experiments of neutral atom lithography. The He* beam was used to pattern material surfaces using a resist-based lithography technique, where the pattern was determined by either mechanical or optical masks. The optical masks produced features with a separation of half the wavelength of the light used. Patterning was successfully demonstrated with both IR and UV optical masks. The etched pattern resolution was ˜ 100 nm and limited by the material surface. Further experiments were performed studying the ability of the bichromatic force to cool. The finite velocity range of the BF allows estimation of a characteristic cooling time which is independent of the excited state lifetime, only depending on the atomic mass and optical transition energy. Past experiments, including the helium collimation used for neutral atom lithography, have demonstrated that the BF can collimate and longitudinally slow atomic beams, but required long interaction times that included many spontaneous emission (SE) events. The effect of SE can be mitigated, and is predicted to not be necessary for BF cooling. Since the BF cooling time is not related to the excited state lifetime, a transition can be chosen such that the cooling time is shorter than the SE cycle time, allowing direct laser cooling on atoms and molecules that do not have cycling transitions. Experiments using the helium 2 3S-3P transition were chosen because the BF cooling time (285 ns) is on the order of the average SE cycle time (260 ns). Numerical simulations of the experimental system were run predicting compression of the

  10. Apodized Phase Mask Coronagraphs

    NASA Astrophysics Data System (ADS)

    Carlotti, Alexis

    2013-01-01

    Among the optical instruments proposed to detect and characterize exoplanets, phase masks coronagraphs offer very small inner working angles. Designed for off-axis telescopes, their performance is greatly reduced when used with centrally obstructed apertures such as those of the Palomar telescope, the very large telescope, or the James Webb space telescope. However, a clear circular aperture is not the only pupil shape for which a phase mask coronagraph can work properly. In fact, for a given centrally obstructed aperture, we show that it is possible to compute optimal apodizers that help achieve stellar extinction levels similar to those obtained in the ideal case of an off-axis telescope. Trade-offs exist between these levels, the transmission of the apodizer, and the area covered by the Lyot stop. We detail the Fourier optics formalism that makes these optimizations possible, as well as a few examples of shaped pupils. Some are designed for a four-quadrants phase mask, and some others for a vortex phase mask. We also offer a comparison with a coronagraph solely composed of a shaped pupil.

  11. Masked mycotoxins: A review

    PubMed Central

    Berthiller, Franz; Crews, Colin; Dall'Asta, Chiara; Saeger, Sarah De; Haesaert, Geert; Karlovsky, Petr; Oswald, Isabelle P; Seefelder, Walburga; Speijers, Gerrit; Stroka, Joerg

    2013-01-01

    The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders. PMID:23047235

  12. Competing for Consciousness: Prolonged Mask Exposure Reduces Object Substitution Masking

    ERIC Educational Resources Information Center

    Goodhew, Stephanie C.; Visser, Troy A. W.; Lipp, Ottmar V.; Dux, Paul E.

    2011-01-01

    In object substitution masking (OSM) a sparse, temporally trailing 4-dot mask impairs target identification, even though it has different contours from, and does not spatially overlap with the target. Here, we demonstrate a previously unknown characteristic of OSM: Observers show reduced masking at prolonged (e.g., 640 ms) relative to intermediate…

  13. Mask Blank Defect Detection

    SciTech Connect

    Johnson, M A; Sommargren, G E

    2000-02-04

    Mask blanks are the substrates that hold the master patterns for integrated circuits. Integrated circuits are semiconductor devices, such as microprocessors (mPs), dynamic random access memory (DRAMs), and application specific integrated circuits (ASICs) that are central to the computer, communication, and electronics industries. These devices are fabricated using a set of master patterns that are sequentially imaged onto light-sensitive coated silicon wafers and processed to form thin layers of insulating and conductive materials on top of the wafer. These materials form electrical paths and transistors that control the flow of electricity through the device. For the past forty years the semiconductor industry has made phenomenal improvements in device functionality, compactness, speed, power, and cost. This progress is principally due to the exponential decrease in the minimum feature size of integrated circuits, which has been reduced by a factor of {radical}2 every three years. Since 1992 the Semiconductor Industry Association (SIA) has coordinated the efforts of producing a technology roadmap for semiconductors. In the latest document, ''The International Technology Roadmap for Semiconductors: 1999'', future technology nodes (minimum feature sizes) and targeted dates were specified and are summarized in Table 1. Lithography is the imaging technology for producing a de-magnified image of the mask on the wafer. A typical de-magnification factor is 4. Mask blank defects as small as one-eighth the equivalent minimum feature size are printable and may cause device failure. Defects might be the result of the surface preparation, such as polishing, or contamination due to handling or the environment. Table 2 shows the maximum tolerable defect sizes on the mask blank for each technology node. This downward trend puts a tremendous burden on mask fabrication, particularly in the area of defect detection and reduction. A new infrastructure for mask inspection will be

  14. Helium-Recycling Plant

    NASA Technical Reports Server (NTRS)

    Cook, Joseph

    1996-01-01

    Proposed system recovers and stores helium gas for reuse. Maintains helium at 99.99-percent purity, preventing water vapor from atmosphere or lubricating oil from pumps from contaminating gas. System takes in gas at nearly constant low back pressure near atmospheric pressure; introduces little or no back pressure into source of helium. Concept also extended to recycling of other gases.

  15. Masked multichannel analyzer

    DOEpatents

    Winiecki, A.L.; Kroop, D.C.; McGee, M.K.; Lenkszus, F.R.

    1984-01-01

    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  16. Masked multichannel analyzer

    DOEpatents

    Winiecki, Alan L.; Kroop, David C.; McGee, Marilyn K.; Lenkszus, Frank R.

    1986-01-01

    An analytical instrument and particularly a time-of-flight-mass spectrometer for processing a large number of analog signals irregularly spaced over a spectrum, with programmable masking of portions of the spectrum where signals are unlikely in order to reduce memory requirements and/or with a signal capturing assembly having a plurality of signal capturing devices fewer in number than the analog signals for use in repeated cycles within the data processing time period.

  17. [Intubating laryngeal mask].

    PubMed

    Langenstein, H; Möller, F

    1998-01-01

    To improve the success of blind intubation through a laryngeal mask, Dr. A.I.J. Brain constructed the intubating laryngeal mask airway (ILMA), marketed under the name Fastrach. The new construction allows blind intubation with highly flexible endotracheal tubes up to 8 mm ID with cuff (straight Woodbridge type), securing the airway around the intubation process and maintaining most of the characteristics of a standard laryngeal mask airway (SLMA), including contraindications. An additional contraindication is the existence of a Zenker diverticle. Up to now, eight working groups reported a success rate of blind intubation through the ILMA of more than 90% in about 1,200 patients, with a success rate of blind intubation of more than 50% for the first intubation attempt. Ten percent of the patients were difficult to intubate with the same success rate for blind intubation as in normal patients. Reduced mouth opening does not seem to hinder the use of the ILMA in spite of its increased outer diameter of 2 cm, as long as it is possible to enlarge the mouth opening to > 2 cm during anaesthesia. The new ILMA more than doubles the success of blind intubation compared to an SLMA, irrespective of a large variety of intubation difficulties. Correct judgement of endotracheal tube position is mandatory. The ILMA has the potential to be used in patients who are difficult to intubate and to substitute the SLMA in "cannot ventilate--cannot intubate" situations. The future will show if the ILMA also will improve emergency airway management by inexperienced personnel, including intubation, as has been shown for the standard laryngeal mask airway in cardiopulmonary resuscitation for ventilation only. PMID:9611362

  18. Wavelength dependent mask defects

    NASA Astrophysics Data System (ADS)

    Badger, Karen; Butt, Shahid; Burnham, Jay; Faure, Tom; Hibbs, Michael; Rankin, Jed; Thibault, David; Watts, Andrew

    2005-05-01

    For years there has been a mismatch between the photomask inspection wavelength and the usage conditions. While the non-actinic inspection has been a source for concern, there has been essentially no evidence that a defect "escaped" the mask production process due to the inspection mismatch. This paper will describe the discovery of one such defect, as well as the diagnostic and inspection techniques used to identify the location, analyze the composition, and determine the source of the printed wafer defect. Conventional mask inspection techniques revealed no defects, however an actinic Aerial Image Metrology System (AIMS) revealed a 1.5 mm region on the mask with up to 59% transmission reduction at 193 nm. Further diagnostics demonstrated a strong wavelength dependence which accounted for the near invisibility of the defect at I line (365 nm) or even DUV (248 nm) wavelengths, which had 0% and 5% respective transmission reductions. Using some creative imaging techniques via AIMS tool and modeling, the defect was deduced to have a three dimensional Gaussian absorption character, with total width approximately 1.5 mm. Several non-destructive diagnostic techniques were developed to determine the composition and location of the defect within the substrate. These results will be described in addition to identifying methods for ensuring product quality in the absence of actinic inspection.

  19. Mask strategy at International SEMATECH

    NASA Astrophysics Data System (ADS)

    Kimmel, Kurt R.

    2002-08-01

    International SEMATECH (ISMT) is a consortium consisting of 13 leading semiconductor manufacturers from around the globe. Its objective is to develop the infrastructure necessary for its member companies to realize the International Technology Roadmap for Semiconductors (ITRS) through efficiencies of shared development resources and knowledge. The largest area of effort is lithography, recognized as a crucial enabler for microelectronics technology progress. Within the Lithography Division, most of the efforts center on mask-related issues. The development strategy at International SEMATCH will be presented and the interlock of lithography projects clarified. Because of the limited size of the mask production equipment market, the business case is weak for aggressive investment commensurate with the pace of the International Technology Roadmap for Semiconductors. With masks becoming the overwhelming component of lithography cost, new ways of reducing or eliminating mask costs are being explored. Will mask technology survive without a strong business case? Will the mask industry limit the growth of the semiconductor industry? Are advanced masks worth their escalating cost? An analysis of mask cost from the perspective of mask value imparted to the user is presented with examples and generic formulas for the reader to apply independently. A key part to the success for both International SEMATECH and the industry globally will be partnerships on both the local level between mask-maker and mask-user, and the macro level where global collaborations will be necessary to resolve technology development cost challenges.

  20. Nanostructures from hydrogen implantation of metals.

    SciTech Connect

    McWatters, Bruce Ray; Causey, Rion A.; DePuit, Ryan J.; Yang, Nancy Y. C.; Ong, Markus D.

    2009-09-01

    This study investigates a pathway to nanoporous structures created by hydrogen implantation in aluminum. Previous experiments for fusion applications have indicated that hydrogen and helium ion implantations are capable of producing bicontinuous nanoporous structures in a variety of metals. This study focuses specifically on hydrogen and helium implantations of aluminum, including complementary experimental results and computational modeling of this system. Experimental results show the evolution of the surface morphology as the hydrogen ion fluence increases from 10{sup 17} cm{sup -2} to 10{sup 18} cm{sup -2}. Implantations of helium at a fluence of 10{sup 18} cm{sup -2} produce porosity on the order of 10 nm. Computational modeling demonstrates the formation of alanes, their desorption, and the resulting etching of aluminum surfaces that likely drives the nanostructures that form in the presence of hydrogen.

  1. Mask industry assessment trend analysis

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Hector, Scott; Marmillion, Pat; Lercel, Michael

    2006-06-01

    Microelectronics industry leaders routinely name mask cost and cycle time as top issues of concern. In 2002, a survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. The survey is designed with the input of mask technologists from semiconductor manufacturers, merchant mask suppliers, and makers of mask equipment. The 2005 survey was the fourth in the current series of annual surveys. The survey data can be used as a baseline for the mask industry and the microelectronics industry to gain a perspective on the technical and business status of the mask industry. The results may be used to guide future investments on critical path issues. Questions are grouped into categories: general business profile information, data processing, yields and yield loss mechanisms, delivery times, returns and services, operating cost factors, and equipment utilization. Because the questions covering operating cost factors and equipment utilization were just added to the survey, no trend analysis is possible. Within each category are many questions that together create a detailed profile of both the business and technical status of the mask industry. The assessment participation has changed from year to year. The 2005 survey, for example, includes inputs from eight major global merchant and captive mask manufacturers whose revenue represents approximately 85% of the global mask market.

  2. Mask fabrication process

    DOEpatents

    Cardinale, Gregory F.

    2000-01-01

    A method for fabricating masks and reticles useful for projection lithography systems. An absorber layer is conventionally patterned using a pattern and etch process. Following the step of patterning, the entire surface of the remaining top patterning photoresist layer as well as that portion of an underlying protective photoresist layer where absorber material has been etched away is exposed to UV radiation. The UV-exposed regions of the protective photoresist layer and the top patterning photoresist layer are then removed by solution development, thereby eliminating the need for an oxygen plasma etch and strip and chances for damaging the surface of the substrate or coatings.

  3. Masks of the Universe

    NASA Astrophysics Data System (ADS)

    Harrison, Edward

    2011-11-01

    Preface; Introducing the masks; Part I. Worlds in the Making: 1. The magic Universe; 2. The mythic Universe; 3. The geometric Universe; 4. The medieval Universe; 5. The infinite Universe; 6. The mechanistic Universe; Part II. The Heart Divine: 7. Dance of the atoms and waves; 8. Fabric of space and time; 9. Nearer to the heart's desire; 10. The cosmic tide; 11. Do dreams ever come true?; Part III. The Cloud of Unknowing: 12. The witch universe; 13. The spear of Archytas; 14. All that is made; 15. The cloud of unknowing; 16. Learned ignorance.

  4. Helium bubble evolution in a Zr–Sn–Nb–Fe–Cr alloy during post-annealing: An in-situ investigation

    SciTech Connect

    Shen, H.H.; Peng, S.M.; Chen, B.; Naab, F.N.; Sun, G.A.; Zhou, W.; Xiang, X.; Sun, K.; Zu, X.T.

    2015-09-15

    The formation of helium bubbles is considered to be detrimental to the mechanical performance of the nuclear materials. The growth behaviors of helium bubbles in a helium ion implanted Zr–Sn–Nb–Fe–Cr alloy with respect to the helium fluence and subsequently annealing procedure were investigated by in-situ transmission electron microscopy. In the as-implanted sample, the measured size distributions of the helium bubbles are consistent with the simulated helium concentrations. Moreover, the mean size of the helium bubbles increases with the increase of the irradiation temperatures and the helium fluence. The in-situ heating study performed in a transmission electron microscope indicates that the mean size of the helium bubbles increase slowly below 923 K and dramatically above 923 K. The coarsening mechanism of the helium bubbles in the alloy is suggested based on the study. - Highlights: • Helium bubble growth in zirconium with annealing was in-situ investigated in TEM. • The mean helium bubble size increase with helium fluence and annealing temperature. • Helium bubble size distribution is same as that of helium concentration by SRIM. • Mean bubble size increases slowly and quickly with temperature below and above 923 K. • The growth mechanism of the helium bubbles in Zr alloy has been discussed.

  5. A Masked Photocathode in Photoinjector

    SciTech Connect

    Qiang, Ji

    2010-12-14

    In this paper, we propose a masked photocathode inside the photoinjector for generating high brightness election beam. Instead of mounting the photocathode onto an electrode, an electrode with small hole is used as a mask to shield the photocathode from the accelerating vacuum chamber. Using such a masked photocathode will make the replacement of photocathode material easy by rotating the photocathode behind the electrode into the hole. Furthermore, this helps reduce the dark current or secondary electron emission from the photocathode material. The masked photocathode also provides transverse cut-off to a Gaussian laser beam that reduces electron beam emittance growth from nonlinear space-charge effects.

  6. Current status of NGL masks

    NASA Astrophysics Data System (ADS)

    Walker, David M.

    2000-07-01

    The manufacture of Next Generation Lithography reticles presents many challenges. Extremely small critical dimension and image placement error budgets; novel substrates including membranes and multi-layer reflective coatings; and inspection, detection and repair of subresolution defects will force revolutionary change in the infrastructure of mask technology. This paper surveys current NGL mask designs, structures, materials and manufacturing capabilities. Results from mask fabrication, physical modeling, error budget analysis and extensive experience in building X-Ray membrane masks are presented to develop process learning plans to meet future product specifications.

  7. Optical inspection of NGL masks

    NASA Astrophysics Data System (ADS)

    Pettibone, Donald W.; Stokowski, Stanley E.

    2004-12-01

    For the last five years KLA-Tencor and our joint venture partners have pursued a research program studying the ability of optical inspection tools to meet the inspection needs of possible NGL lithographies. The NGL technologies that we have studied include SCALPEL, PREVAIL, EUV lithography, and Step and Flash Imprint Lithography. We will discuss the sensitivity of the inspection tools and mask design factors that affect tool sensitivity. Most of the work has been directed towards EUV mask inspection and how to optimize the mask to facilitate inspection. Our partners have succeeded in making high contrast EUV masks ranging in contrast from 70% to 98%. Die to die and die to database inspection of EUV masks have been achieved with a sensitivity that is comparable to what can be achieved with conventional photomasks, approximately 80nm defect sensitivity. We have inspected SCALPEL masks successfully. We have found a limitation of optical inspection when applied to PREVAIL stencil masks. We have run inspections on SFIL masks in die to die, reflected light, in an effort to provide feedback to improve the masks. We have used a UV inspection system to inspect both unpatterned EUV substrates (no coatings) and blanks (with EUV multilayer coatings). These inspection results have proven useful in driving down the substrate and blank defect levels.

  8. Helium segregation on surfaces of plasma-exposed tungsten

    DOE PAGESBeta

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D.; Wirth, Brian D.

    2016-01-21

    Here we report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He-n (1 <= n <= 7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides themore » thermodynamic driving force for surface segregation. Elastic interaction force induces drift fluxes of these mobile Hen clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters' drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. Moreover, these near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.« less

  9. Helium segregation on surfaces of plasma-exposed tungsten

    NASA Astrophysics Data System (ADS)

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D.; Wirth, Brian D.

    2016-02-01

    We report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He n (1  ⩽  n  ⩽  7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides the thermodynamic driving force for surface segregation. This elastic interaction force induces drift fluxes of these mobile He n clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters’ drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. These near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.

  10. Helium segregation on surfaces of plasma-exposed tungsten.

    PubMed

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D; Wirth, Brian D

    2016-02-17

    We report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He n (1⩽  n  ⩽  7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides the thermodynamic driving force for surface segregation. This elastic interaction force induces drift fluxes of these mobile He n clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters' drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. These near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components. PMID:26794828

  11. The implementation of Mask-Ed: reflections of academic participants.

    PubMed

    Reid-Searl, Kerry; Levett-Jones, Tracy; Cooper, Simon; Happell, Brenda

    2014-09-01

    This paper profiles the findings from a study that explored the perspectives and experiences of nurse educators who implemented a novel simulation approach termed Mask-Ed. The technique involves the educator wearing a silicone mask and or body parts and transforming into a character. The premise of this approach is that the masked educator has domain specific knowledge related to the simulation scenario and can transmit this to learners in a way that is engaging, realistic, spontaneous and humanistic. Nurse educators charged with the responsibility of implementing Mask-Ed in three universities were invited to participate in the study by attending an introductory workshop, implementing the technique and then journaling their experiences, insights and perspectives over a 12 month period. The journal entries were then thematically analysed. Key themes were categorised under the headings of Preparation, Implementation and Impact; Reflexivity and Responsiveness; Student Engagement and Ownership; and Teaching and Learning. Mask-Ed is a simulation approach which allows students to interact with the 'characters' in humanistic ways that promote person-centred care and therapeutic communication. This simulation approach holds previously untapped potential for a range of learning experiences, however, to be effective, adequate resourcing, training, preparation and practice is required. PMID:24906681

  12. What Is Being Masked in Object Substitution Masking?

    ERIC Educational Resources Information Center

    Gellatly, Angus; Pilling, Michael; Cole, Geoff; Skarratt, Paul

    2006-01-01

    Object substitution masking (OSM) is said to occur when a perceptual object is hypothesized that is mismatched by subsequent sensory evidence, leading to a new hypothesized object being substituted for the first. For example, when a brief target is accompanied by a longer lasting display of nonoverlapping mask elements, reporting of target…

  13. SEMATECH EUVL mask program status

    NASA Astrophysics Data System (ADS)

    Yun, Henry; Goodwin, Frank; Huh, Sungmin; Orvek, Kevin; Cha, Brian; Rastegar, Abbas; Kearney, Patrick

    2009-04-01

    As we approach the 22nm half-pitch (hp) technology node, the industry is rapidly running out of patterning options. Of the several lithography techniques highlighted in the International Technology Roadmap for Semiconductors (ITRS), the leading contender for the 22nm hp insertion is extreme ultraviolet lithography (EUVL). Despite recent advances with EUV resist and improvements in source power, achieving defect free EUV mask blank and enabling the EUV mask infrastructure still remain critical issues. To meet the desired EUV high volume manufacturing (HVM) insertion target date of 2013, these obstacles must be resolved on a timely bases. Many of the EUV mask related challenges remain in the pre-competitive stage and a collaborative industry based consortia, such as SEMATECH can play an important role to enable the EUVL landscape. SEMATECH based in Albany, NY is an international consortium representing several of the largest manufacturers in the semiconductor market. Full members include Intel, Samsung, AMD, IBM, Panasonic, HP, TI, UMC, CNSE (College of Nanoscience and Engineering), and Fuller Road Management. Within the SEMATECH lithography division a major thrust is centered on enabling the EUVL ecosystem from mask development, EUV resist development and addressing EUV manufacturability concerns. An important area of focus for the SEMATECH mask program has been the Mask Blank Development Center (MBDC). At the MBDC key issues in EUV blank development such as defect reduction and inspection capabilities are actively pursued together with research partners, key suppliers and member companies. In addition the mask program continues a successful track record of working with the mask community to manage and fund critical mask tools programs. This paper will highlight recent status of mask projects and longer term strategic direction at the MBDC. It is important that mask technology be ready to support pilot line development HVM by 2013. In several areas progress has been

  14. Masked Proportional Routing

    NASA Technical Reports Server (NTRS)

    Wolpert, David

    2004-01-01

    Masked proportional routing is an improved procedure for choosing links between adjacent nodes of a network for the purpose of transporting an entity from a source node ("A") to a destination node ("B"). The entity could be, for example, a physical object to be shipped, in which case the nodes would represent waypoints and the links would represent roads or other paths between waypoints. For another example, the entity could be a message or packet of data to be transmitted from A to B, in which case the nodes could be computer-controlled switching stations and the links could be communication channels between the stations. In yet another example, an entity could represent a workpiece while links and nodes could represent, respectively, manufacturing processes and stages in the progress of the workpiece towards a finished product. More generally, the nodes could represent states of an entity and the links could represent allowed transitions of the entity. The purpose of masked proportional routing and of related prior routing procedures is to schedule transitions of entities from their initial states ("A") to their final states ("B") in such a manner as to minimize a cost or to attain some other measure of optimality or efficiency. Masked proportional routing follows a distributed (in the sense of decentralized) approach to probabilistically or deterministically choosing the links. It was developed to satisfy a need for a routing procedure that 1. Does not always choose the same link(s), even for two instances characterized by identical estimated values of associated cost functions; 2. Enables a graceful transition from one set of links to another set of links as the circumstances of operation of the network change over time; 3. Is preferably amenable to separate optimization of different portions of the network; 4. Is preferably usable in a network in which some of the routing decisions are made by one or more other procedure(s); 5. Preferably does not cause an

  15. Mask industry assessment trend analysis

    NASA Astrophysics Data System (ADS)

    Shelden, Gilbert; Marmillion, Patricia; Hughes, Greg

    2008-04-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH and administered by SEMI North America to gather information about the mask industry as an objective assessment of its overall condition. This year's survey data were presented in detail at BACUS and the detailed trend analysis presented at EMLC. The survey is designed with the input of semiconductor company mask technologists, merchant mask suppliers, and industry equipment makers. This year's assessment is the sixth in the current series of annual reports. With continued industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments on critical path issues. This year's survey is basically the same as the 2005 and 2006 surveys. Questions are grouped into eight categories: General Business Profile Information, Data Processing, Yields and Yield Loss, Mechanisms, Delivery Times, Returns and Services, Operating Cost Factors, and Equipment Utilization. Within each category is a multitude of questions that creates a detailed profile of both the business and technical status of the critical mask industry. Note: the questions covering operating cost factors and equipment utilization were added to the survey only in 2005; therefore, meaningful trend analysis is not available.

  16. Mask industry assessment trend analysis

    NASA Astrophysics Data System (ADS)

    Hughes, Greg; Yun, Henry

    2009-01-01

    Microelectronics industry leaders routinely name the cost and cycle time of mask technology and mask supply as top critical issues. A survey was created with support from SEMATECH to gather information about the mask industry as an objective assessment of its overall condition. This year's survey data were presented in detail at BACUS and the detailed trend analysis presented at EMLC. The survey is designed with the input of semiconductor company mask technologists and merchant mask suppliers. This year's assessment is the seventh in the current series of annual reports. With continued industry support, the report can be used as a baseline to gain perspective on the technical and business status of the mask and microelectronics industries. The report will continue to serve as a valuable reference to identify the strengths and opportunities of the mask industry. The results will be used to guide future investments on critical path issues. This year's survey is basically the same as the surveys in 2005 through 2007. Questions are grouped into seven categories: General Business Profile Information, Data Processing, Yields and Yield Loss, Mechanisms, Delivery Times, Returns, and Services. (Examples are given below). Within each category is a multitude of questions that creates a detailed profile of both the business and technical status of the critical mask industry.

  17. Combining Simultaneous with Temporal Masking

    ERIC Educational Resources Information Center

    Hermens, Frouke; Herzog, Michael H.; Francis, Gregory

    2009-01-01

    Simultaneous and temporal masking are two frequently used techniques in psychology and vision science. Although there are many studies and theories related to each masking technique, there are no systematic investigations of their mutual relationship, even though both techniques are often applied together. Here, the authors show that temporal…

  18. Masked Repetition Priming Using Magnetoencephalography

    ERIC Educational Resources Information Center

    Monahan, Philip J.; Fiorentino, Robert; Poeppel, David

    2008-01-01

    Masked priming is used in psycholinguistic studies to assess questions about lexical access and representation. We present two masked priming experiments using MEG. If the MEG signal elicited by words reflects specific aspects of lexical retrieval, then one expects to identify specific neural correlates of retrieval that are sensitive to priming.…

  19. Advanced Mask Aligner Lithography (AMALITH)

    NASA Astrophysics Data System (ADS)

    Voelkel, Reinhard; Vogler, Uwe; Bramati, Arianna

    2015-03-01

    Mask aligner lithography is very attractive for less-critical lithography layers and is widely used for LED, display, CMOS image sensor, micro-fluidics and MEMS manufacturing. Mask aligner lithography is also a preferred choice the semiconductor back-end for 3D-IC, TSV interconnects, advanced packaging (AdP) and wafer-level-packaging (WLP). Mask aligner lithography is a mature technique based on shadow printing and has not much changed since the 1980s. In shadow printing lithography a geometric pattern is transferred by free-space propagation from a photomask to a photosensitive layer on a wafer. The inherent simplicity of the pattern transfer offers ease of operation, low maintenance, moderate capital expenditure, high wafers-per-hour (WPH) throughput, and attractive cost-of-ownership (COO). Advanced mask aligner lithography (AMALITH) comprises different measures to improve shadow printing lithography beyond current limits. The key enabling technology for AMALITH is a novel light integrator systems, referred to as MO Exposure Optics® (MOEO). MOEO allows to fully control and shape the properties of the illumination light in a mask aligner. Full control is the base for accurate simulation and optimization of the shadow printing process (computational lithography). Now photolithography enhancement techniques like customized illumination, optical proximity correction (OPC), phase masks (AAPSM), half-tone lithography and Talbot lithography could be used in mask aligner lithography. We summarize the recent progress in advanced mask aligner lithography (AMALITH) and discuss possible measures to further improve shadow printing lithography.

  20. Cochlear Implants.

    ERIC Educational Resources Information Center

    Clark, Catherine; Scott, Larry

    This brochure explains what a cochlear implant is, lists the types of individuals with deafness who may be helped by a cochlear implant, describes the process of evaluating people for cochlear implants, discusses the surgical process for implanting the aid, traces the path of sound through the cochlear implant to the brain, notes the costs of…

  1. Defect tolerant transmission lithography mask

    DOEpatents

    Vernon, Stephen P.

    2000-01-01

    A transmission lithography mask that utilizes a transparent substrate or a partially transparent membrane as the active region of the mask. A reflective single layer or multilayer coating is deposited on the membrane surface facing the illumination system. The coating is selectively patterned (removed) to form transmissive (bright) regions. Structural imperfections and defects in the coating have negligible effect on the aerial image of the mask master pattern since the coating is used to reflect radiation out of the entrance pupil of the imaging system. Similarly, structural imperfections in the clear regions of the membrane have little influence on the amplitude or phase of the transmitted electromagnetic fields. Since the mask "discards," rather than absorbs, unwanted radiation, it has reduced optical absorption and reduced thermal loading as compared to conventional designs. For EUV applications, the mask circumvents the phase defect problem, and is independent of the thermal load during exposure.

  2. Effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance

    NASA Astrophysics Data System (ADS)

    Dietze, Uwe; Dress, Peter; Waehler, Tobias; Singh, Sherjang; Jonckheere, Rik; Baudemprez, Bart

    2011-03-01

    Extreme Ultraviolet Lithography (EUVL) is considered the leading lithography technology choice for semiconductor devices at 16nm HP node and beyond. However, before EUV Lithography can enter into High Volume Manufacturing (HVM) of advanced semiconductor devices, the ability to guarantee mask integrity at point-of-exposure must be established. Highly efficient, damage free mask cleaning plays a critical role during the mask manufacturing cycle and throughout the life of the mask, where the absence of a pellicle to protect the EUV mask increases the risk of contamination during storage, handling and use. In this paper, we will present effective EUVL mask cleaning technology solutions for mask manufacturing and in-fab mask maintenance, which employs an intelligent, holistic approach to maximize Mean Time Between Cleans (MBTC) and extend the useful life span of the reticle. The data presented will demonstrate the protection of the capping and absorber layers, preservation of pattern integrity as well as optical and mechanical properties to avoid unpredictable CD-linewidth and overlay shifts. Experiments were performed on EUV blanks and pattern masks using various process conditions. Conditions showing high particle removal efficiency (PRE) and minimum surface layer impact were then selected for durability studies. Surface layer impact was evaluated over multiple cleaning cycles by means of UV reflectivity metrology XPS analysis and wafer prints. Experimental results were compared to computational models. Mask life time predictions where made using the same computational models. The paper will provide a generic overview of the cleaning sequence which yielded best results, but will also provide recommendations for an efficient in-fab mask maintenance scheme, addressing handling, storage, cleaning and inspection.

  3. Effect of using stencil masks made by focused ion beam milling on permalloy (Ni81Fe19) nanostructures.

    PubMed

    Bates, J R; Miyahara, Y; Burgess, J A J; Iglesias-Freire, O; Grütter, P

    2013-03-22

    Focused ion beam (FIB) milling is a common fabrication technique to make nanostencil masks which has the unintended consequence of gallium ion implantation surrounding milled features in silicon nitride membranes. We observe major changes in film structure, chemical composition, and magnetic behaviour of permalloy nanostructures deposited by electron beam evaporation using silicon nitride stencil masks made by a FIB as compared to stencil masks made by regular lithography techniques. We characterize the stenciled structures and both types of masks using transmission electron microscopy, electron energy loss spectroscopy, energy dispersive x-ray spectroscopy, magnetic force microscopy and kelvin probe force microscopy. All these techniques demonstrate distinct differences at a length scale of a 1-100 nm for the structures made using stencil mask fabricated using a FIB. The origin of these differences seems to be related to the presence of implanted ions, a detailed understanding of the mechanism however remains to be developed. PMID:23449320

  4. Bringing mask repair to the next level

    NASA Astrophysics Data System (ADS)

    Edinger, K.; Wolff, K.; Steigerwald, H.; Auth, N.; Spies, P.; Oster, J.; Schneider, H.; Budach, M.; Hofmann, T.; Waiblinger, M.

    2014-10-01

    Mask repair is an essential step in the mask manufacturing process as the extension of 193nm technology and the insertion of EUV are drivers for mask complexity and cost. The ability to repair all types of defects on all mask blank materials is crucial for the economic success of a mask shop operation. In the future mask repair is facing several challenges. The mask minimum features sizes are shrinking and require a higher resolution repair tool. At the same time mask blanks with different new mask materials are introduced to optimize optical performance and long term durability. For EUV masks new classes of defects like multilayer and phase defects are entering the stage. In order to achieve a high yield, mask repair has to cover etch and deposition capabilities and must not damage the mask. These challenges require sophisticated technologies to bring mask repair to the next level. For high end masks ion-beam based and e-based repair technologies are the obvious choice when it comes to the repair of small features. Both technologies have their pro and cons. The scope of this paper is to review and compare the performance of ion-beam based mask repair to e-beam based mask repair. We will analyze the limits of both technologies theoretically and experimentally and show mask repair related performance data. Based on this data, we will give an outlook to future mask repair tools.

  5. Masks for extreme ultraviolet lithography

    SciTech Connect

    Cardinale, G; Goldsmith, J; Kearney, P A; Larson, C; Moore, C E; Prisbrey, S; Tong, W; Vernon, S P; Weber, F; Yan, P-Y

    1998-09-01

    In extreme ultraviolet lithography (EUVL), the technology specific requirements on the mask are a direct consequence of the utilization of radiation in the spectral region between 10 and 15 nm. At these wavelengths, all condensed materials are highly absorbing and efficient radiation transport mandates the use of all-reflective optical systems. Reflectivity is achieved with resonant, wavelength-matched multilayer (ML) coatings on all of the optical surfaces - including the mask. The EUV mask has a unique architecture - it consists of a substrate with a highly reflective ML coating (the mask blank) that is subsequently over-coated with a patterned absorber layer (the mask). Particulate contamination on the EUVL mask surface, errors in absorber definition and defects in the ML coating all have the potential to print in the lithographic process. While highly developed technologies exist for repair of the absorber layer, no viable strategy for the repair of ML coating defects has been identified. In this paper the state-of-the-art in ML deposition technology, optical inspection of EUVL mask blank defects and candidate absorber patterning approaches are reviewed.

  6. Sensitivity of coded mask telescopes.

    PubMed

    Skinner, Gerald K

    2008-05-20

    Simple formulas are often used to estimate the sensitivity of coded mask x-ray or gamma-ray telescopes, but these are strictly applicable only if a number of basic assumptions are met. Complications arise, for example, if a grid structure is used to support the mask elements, if the detector spatial resolution is not good enough to completely resolve all the detail in the shadow of the mask, or if any of a number of other simplifying conditions are not fulfilled. We derive more general expressions for the Poisson-noise-limited sensitivity of astronomical telescopes using the coded mask technique, noting explicitly in what circumstances they are applicable. The emphasis is on using nomenclature and techniques that result in simple and revealing results. Where no convenient expression is available a procedure is given that allows the calculation of the sensitivity. We consider certain aspects of the optimization of the design of a coded mask telescope and show that when the detector spatial resolution and the mask to detector separation are fixed, the best source location accuracy is obtained when the mask elements are equal in size to the detector pixels. PMID:18493279

  7. Helium effects on creep properties of Fe-14CrWTi ODS steel at 650 °C

    NASA Astrophysics Data System (ADS)

    Chen, J.; Jung, P.; Rebac, T.; Duval, F.; Sauvage, T.; de Carlan, Y.; Barthe, M. F.

    2014-10-01

    In the present paper, the effects of helium on creep properties of Fe-14CrWTi ODS steel were studied by in-beam and post He-implantation creep tests. In-situ creep was performed in an in-beam creep device under uniaxial tensile stresses from 350 to 370 MPa during homogeneous helium implantation. Helium ions of energies varying from 0 to 25 MeV were implanted at a rate of 6 × 10-3 appm/s (corresponding to a displacement dose rate of 1.5 × 10-6 dpa/s). The average temperature was controlled to 650 °C within ±2 °C. In addition, post He-implantation creep tests were conducted at 650 °C as well. Subsequently, fracture surfaces and helium bubble evolution were studied in detail by SEM and TEM observations, respectively. Preliminary creep results show that helium slightly shortens the creep life time of ODS steel at 650 °C. Fracture surfaces of reference as well as implanted specimens, show areas with various grades of deformation. Areas of highest deformation can be interpreted as necking, while areas of low deformation show in helium implanted specimens a more granular structure. The results are discussed in terms of possible embrittlement of ODS steels by helium.

  8. Hg-Mask Coronagraph

    NASA Astrophysics Data System (ADS)

    Bourget, P.; Veiga, C. H.; Vieira Martins, R.; Assus, P.; Colas, F.

    In order to optimize the occulting process of a Lyot coronagraph and to provide a high dynamic range imaging, a new kind of occulting disk has been developed at the National Observatory of Rio de Janeiro. A mercury (Hg) drop glued onto an optical window by molecular cohesion and compressed by a pellicle film is used as the occulting disk. The minimum of the superficial tension potential function provides an optical precision (lambda/100) of the toric free surface of the mercury. This process provides a size control for the adaptation to the seeing conditions and to the apparent diameter of a resolved object, and in the case of adaptive optics, to the Airy diameter fraction needed. The occultation is a three dimensional process near the focal plane on the toric free surface that provides an apodization of the occultation. The Hg-Mask coronagraph has been projected for astrometric observations of faint satellites near to Jovian planets and works since 2000 at the 1.6 m telescope of the Pico dos Dias Observatory (OPD - Brazil).

  9. Gentle quantitative measurement of helium density in nanobubbles in silicon by spectrum imaging.

    PubMed

    Alix, Kévin; David, Marie-Laure; Lucas, Guillaume; Alexander, Duncan T L; Pailloux, Frédéric; Hébert, Cécile; Pizzagalli, Laurent

    2015-10-01

    We propose an original method for the determination of the physical properties of nanometer sized helium bubbles using spectrum imaging in an energy-filtered transmission electron microscope. Helium bubbles synthesized by high fluence implantation and thermal annealing in silicon are investigated. The acquisition parameters are determined to optimize both signal/noise ratio and time. The limitations to the extent of observable areas on a typical sample are explained. The necessary data correction and helium K-edge position measurement procedures are detailed and the accuracy of the method is discussed. Finally helium density maps are obtained and discussed. PMID:26093479

  10. Atomistic modeling of growth and coalescence of helium nano-bubbles in tungsten

    NASA Astrophysics Data System (ADS)

    Smirnov, R. D.; Krasheninnikov, S. I.; Guterl, J.

    2015-08-01

    The mechanisms of growth and coalescence of helium nano-bubbles in tungsten are investigated using molecular dynamics simulations. It is shown that crystal symmetries and governed by them properties of dislocations, generated by the growing nano-bubbles, are responsible for main nano-bubble features revealed, including non-spherical shape and anisotropy of surrounding stress field. The transport of helium atoms in non-uniform stress field is simulated at different temperatures and the transport coefficients are determined. The implications of the considered dislocation and helium dynamics on nucleation and growth of bubbles in tungsten with implanted helium are discussed.

  11. The Descending Helium Balloon

    ERIC Educational Resources Information Center

    Helseth, Lars Egil

    2014-01-01

    I describe a simple and fascinating experiment wherein helium leaks out of a rubber balloon, thereby causing it to descend. An estimate of the volumetric leakage rate is made by measuring its rate of descent.

  12. Mask technology for EUV lithography

    NASA Astrophysics Data System (ADS)

    Bujak, M.; Burkhart, Scott C.; Cerjan, Charles J.; Kearney, Patrick A.; Moore, Craig E.; Prisbrey, Shon T.; Sweeney, Donald W.; Tong, William M.; Vernon, Stephen P.; Walton, Christopher C.; Warrick, Abbie L.; Weber, Frank J.; Wedowski, Marco; Wilhelmsen, Karl C.; Bokor, Jeffrey; Jeong, Sungho; Cardinale, Gregory F.; Ray-Chaudhuri, Avijit K.; Stivers, Alan R.; Tejnil, Edita; Yan, Pei-yang; Hector, Scott D.; Nguyen, Khanh B.

    1999-04-01

    Extreme UV Lithography (EUVL) is one of the leading candidates for the next generation lithography, which will decrease critical feature size to below 100 nm within 5 years. EUVL uses 10-14 nm light as envisioned by the EUV Limited Liability Company, a consortium formed by Intel and supported by Motorola and AMD to perform R and D work at three national laboratories. Much work has already taken place, with the first prototypical cameras operational at 13.4 nm using low energy laser plasma EUV light sources to investigate issues including the source, camera, electro- mechanical and system issues, photoresists, and of course the masks. EUV lithograph masks are fundamentally different than conventional photolithographic masks as they are reflective instead of transmissive. EUV light at 13.4 nm is rapidly absorbed by most materials, thus all light transmission within the EUVL system from source to silicon wafer, including EUV reflected from the mask, is performed by multilayer mirrors in vacuum.

  13. Mask materials for powder blasting

    NASA Astrophysics Data System (ADS)

    Wensink, Henk; Jansen, Henri V.; Berenschot, J. W.; Elwenspoek, Miko C.

    2000-06-01

    Powder blasting, or abrasive jet machining (AJM), is a technique in which a particle jet is directed towards a target for mechanical material removal. It is a fast, cheap and accurate directional etch technique for brittle materials such as glass, silicon and ceramics. The particle jet (which expands to about 1 cm in diameter) can be optimized for etching, while the mask defines the small and complex structures. The quality of the mask influences the performance of powder blasting. In this study we tested and compared several mask types and added a new one: electroplated copper. The latter combines a highly resistant mask material for powder blasting with the high-resolution capabilities of lithography, which makes it possible to obtain an accurate pattern transfer and small feature sizes (<50 µm).

  14. Noncavitating Pump For Liquid Helium

    NASA Technical Reports Server (NTRS)

    Hasenbein, Robert; Izenson, Michael; Swift, Walter; Sixsmith, Herbert

    1996-01-01

    Immersion pump features high efficiency in cryogenic service. Simple and reliable centrifugal pump transfers liquid helium with mass-transfer efficiency of 99 percent. Liquid helium drawn into pump by helical inducer, which pressurizes helium slightly to prevent cavitation when liquid enters impeller. Impeller then pressurizes liquid. Purpose of pump to transfer liquid helium from supply to receiver vessel, or to provide liquid helium flow for testing and experimentation.

  15. Tensile behavior of helium charged VTiCrSi type alloys

    NASA Astrophysics Data System (ADS)

    Satou, M.; Koide, H.; Hasegawa, A.; Abe, K.; Kayano, H.; Matsui, H.

    1996-10-01

    Helium effect on the mechanical properties of the alloy V5Ti5Cr1SiAl,Y (nominal) was studied, adopting various helium charging methods and helium-to-dpa ratio. The first method was helium ion implantation using a cyclotron accelerator at Tohoku University, where helium and displacement levels were 50 appm and 0.02 dpa, respectively. The second, helium was charged by tritium trick technique and following neutron irradiation in FFTF/MOTA-2A, associated with about 80 appm He and 43 dpa. The third was dynamic helium charging experiment (DHCE) conducted in FFTF/MOTA-2B, where helium was generated within specimens during neutron irradiation by tritium decay, and the helium-to-dpa ratio was adjusted to simulate the fusion reactor condition, that is, 177 appm He and 24 dpa. The effect of helium on tensile properties of the VTiCrSiAl,Y alloy depended on the helium charging methods. The uniform elongation of the alloy was 3.2% and total elongation was 8.3% at DHCE condition, which was the most fusion relevant condition of the methods. It is important that tensile properties of the present alloy could be acceptable for fusion reactor component materials.

  16. Cosmic Masks Still Dance

    NASA Astrophysics Data System (ADS)

    Block, David L.; Puerari, Ivânio; Frogel, Jay A.; Eskridge, Paul B.; Stockton, Alan; Fuchs, Burkhard

    The Hubble classification scheme of galaxies is based on their optical appearance or `masks'. As one goes from early to late type spirals, both barred and unbarred, the optical appearance will be dominated more and more by the young Population I, i.e., blue stars and dust. Atlases reveal the rich variety of responses of the Population I component of gas and dust (the mask) to the underlying, older, stellar population. However, the gaseous Population I component, may only constitute 5 percent of the dynamical mass of the galaxy. Masks of negligible mass may conceal the human face - and that of galaxy. In the near-infrared, the morphology of older star-dominated disk indicates a simple classification scheme: the dominant Fourier m-mode in the dust penetrated regime, and the associated pitch angle. A ubiquity of low m=1 and m=2 modes is confirmed. On the basis of deprojected H (1.65 μm) and K' (2.1μm) images, we propose that the evolved stellar disks may be grouped into three principal dust penetrated archetypes: those with tightly wound stellar arms characterised by pitch angles at K' of ~ 10^° (the α class), an intermediate group with pitch angles of ~ 25^° (the β class) and thirdly, those with open spirals demarcated by pitch angles at K' of ~ 40^° (the γ bin). Flat or falling rotation curves give rise to the tightly wound α class; rising rotation curves are associated with the open γ class. The observed dust penetrated classes are inextricably related to the rate of shear in the stellar disk, as determined by A/ω. Here A is the first Oort constant andω denotes the angular velocity. There is no correlation between our dust penetrated classes and optical Hubble binning; the Hubble tuning fork does not constrain the morphology of the old stellar Population II disks. NGC 3223 and NGC 7083 (both SbI-II and almost the same absolute blue magnitude) have identical Hubble types and identical luminosity classes; the dust penetrated disk of NGC 3223 has tightly

  17. Visual Masking During Pursuit Eye Movements

    ERIC Educational Resources Information Center

    White, Charles W.

    1976-01-01

    Visual masking occurs when one stimulus interferes with the perception of another stimulus. Investigates which matters more for visual masking--that the target and masking stimuli are flashed on the same part of the retina, or, that the target and mask appear in the same place. (Author/RK)

  18. A quantitative μNRA study of helium intergranular and volume diffusion in sintered UO 2

    NASA Astrophysics Data System (ADS)

    Martin, G.; Desgardin, P.; Sauvage, T.; Garcia, P.; Carlot, G.; Khodja, H.; Barthe, M. F.

    2006-08-01

    To understand the mechanisms related to helium migration in nuclear oxide fuels, 3He was implanted at 2 × 1016 at. cm-2 in UO2 sintered disks. The samples were then annealed at temperatures ranging between 800 °C and 1300 °C. Changes in helium concentrations were investigated using two nuclear reaction analysis techniques based on the 3He(d, α)1H reaction. The first technique uses a macrobeam in order to measure helium depth profiles averaged over a 500 × 500 μm2 area. The second technique uses a microbeam and provides a quantitative two-dimensional helium concentration cartography, for which each pixel corresponds to a depth integrated helium signal. The analysed zones were optically characterised which enabled a detailed analysis of the impact of the material microstructure on helium release from the samples, with an emphasis on the study of grain boundary effects.

  19. Generating mask inspection rules for advanced lithography

    NASA Astrophysics Data System (ADS)

    Badger, Karen; Broadbent, Bill; Dayal, Aditya; Gallagher, Emily; Hsiang, ChingYun; Redding, Vincent

    2005-11-01

    Semiconductor product designs are necessarily constrained by both the wafer and mask lithographic capabilities. When mask image sizes approach the exposure wavelength, optical and resist effects distort the printed images. Applying optical proximity correction (OPC) to design features on the mask compensates for diffraction effects. However, aggressive OPC introduces even smaller minimum features, adds notches and bulges, introduces sub-resolution assist features (SRAFs) and generally creates a more challenging mask design with respect to data handling, printing and inspection. Mask defect inspection is a critical part of the mask process, ensuring that the mask pattern matches the intended design. However, the inspection itself imposes constraints on mask patterns that can be inspected with high defect sensitivity but low nuisance defect counts. These additional restrictions are undesirable since they can reduce the effectiveness of the OPC. IBM and KLA-Tencor have developed a test mask methodology to investigate the inspectability limits of the 576 and 516 mask inspection systems. The test mask design contains a variety of rules or features that currently impose inspectability limits on the inspection tools, in a range of sizes. The design also incorporates many features essential for obtaining valid results, such as a user-friendly layout, multiple pattern orientations, and background patterns. The mask was built and inspected in IBM Burlington's mask house. Preliminary inspection results will be presented; they underscore the importance of understanding both the inspection tool and the mask process when restricting mask design rules.

  20. Rewritable photochromic focal plane masks

    NASA Astrophysics Data System (ADS)

    Molinari, Emilio; Bertarelli, Chiara; Bianco, Andrea; Bortoletto, Fabio; Conconi, Paolo; Crimi, Giuseppe; Gallazzi, Maria C.; Giro, Enrico; Lucotti, Andrea; Pernechele, Claudio; Zerbi, Filippo M.; Zerbi, Giuseppe

    2003-02-01

    The application of organic photochromic materials in astronomy is opening new possibilities which we are investigating in order to design innovative devices for future instrumentation. The photochromic property of transparent/opaque transition (although in a limited wavelength range) and the changes in intrinsic refractive index have led our studies to application in astronomic spectrographs, both as focal plane mask (for MOS application) and as dispersive elements (volume phase holographic gratings, VPHG), respectively. In both cases the possibility to write and erase devices with suitable irradiation has revealed a new perspective for non-disposable and fully customizable items for spectroscopy. Pursuing this goal we have synthesized a series of novel photochromic materials belonging to the diarylethenes. They fulfill the requirements of thermal stability and fatigue resistance necessary to build functional devices. Prototypes of high contrast focal plane mask working in the H-alpha spectral region have been manufactured and characterized both in laboratory and with the AFOSC camera at Asiago telescope (1.8 m). A custom writing robot (ARATRO) which, taking imaging frames and with the aid of interactive mask design software and ad hoc control electronics, is able to write MOS masks, has been constructed. The design of the MOS masks allow the fitting in the AFOSC slit wheel. The overall set-up is ready for the sky tests.

  1. Nanofabrication on unconventional substrates using transferred hard masks

    SciTech Connect

    Li, Luozhou; Bayn, Igal; Lu, Ming; Nam, Chang -Yong; Schroder, Tim; Stein, Aaron; Harris, Nicholas C.; Englund, Dirk

    2015-01-15

    Here, a major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantation are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.

  2. Nanofabrication on unconventional substrates using transferred hard masks

    NASA Astrophysics Data System (ADS)

    Li, Luozhou; Bayn, Igal; Lu, Ming; Nam, Chang-Yong; Schröder, Tim; Stein, Aaron; Harris, Nicholas C.; Englund, Dirk

    2015-01-01

    A major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantation are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates.

  3. Nanofabrication on unconventional substrates using transferred hard masks

    PubMed Central

    Li, Luozhou; Bayn, Igal; Lu, Ming; Nam, Chang-Yong; Schröder, Tim; Stein, Aaron; Harris, Nicholas C.; Englund, Dirk

    2015-01-01

    A major challenge in nanofabrication is to pattern unconventional substrates that cannot be processed for a variety of reasons, such as incompatibility with spin coating, electron beam lithography, optical lithography, or wet chemical steps. Here, we present a versatile nanofabrication method based on re-usable silicon membrane hard masks, patterned using standard lithography and mature silicon processing technology. These masks, transferred precisely onto targeted regions, can be in the millimetre scale. They allow for fabrication on a wide range of substrates, including rough, soft, and non-conductive materials, enabling feature linewidths down to 10 nm. Plasma etching, lift-off, and ion implantation are realized without the need for scanning electron/ion beam processing, UV exposure, or wet etching on target substrates. PMID:25588550

  4. Deciphering gas implantation rate effects on bubble nucleation in tungsten

    NASA Astrophysics Data System (ADS)

    Yang, Zhangcan; Wirth, Brian

    2015-11-01

    We use the object kinetic Monte Carlo code KSOME to study the sub-surface helium clustering behaviour in tungsten at various conditions relevant to plasma exposure of divertor surfaces. In particular, we have investigated helium implantation fluxes from 1020 to 1027 m-2s-1 at temperatures from 400K to 1600K for 100-eV helium ions implanted below tungsten surfaces as a function of pre-existing vacancy concentration. For these conditions, the helium retention rate, the surface areal density of adatoms, and the number density of clusters are analysed. A phase diagram is constructed to summarize the results, which maps the ratio of self-trapped helium to vacancy-trapped helium with respect to the helium flux, the target temperature, and the concentration of pre-existing vacancy. According to the phase diagram, the boundary between the self-trapping dominant regime and the vacancy-trapping dominant regime can be distinguished. In general, pre-existing vacancies are dominant in trapping helium atoms for low fluxes and high temperatures, while self-trapping is dominant for high fluxes. These results provide important insight into the mechanisms of helium clustering for plasma facing components in fusion reactors.

  5. Coatings on reflective mask substrates

    DOEpatents

    Tong, William Man-Wai; Taylor, John S.; Hector, Scott D.; Mangat, Pawitter J. S.; Stivers, Alan R.; Kofron, Patrick G.; Thompson, Matthew A.

    2002-01-01

    A process for creating a mask substrate involving depositing: 1) a coating on one or both sides of a low thermal expansion material EUVL mask substrate to improve defect inspection, surface finishing, and defect levels; and 2) a high dielectric coating, on the backside to facilitate electrostatic chucking and to correct for any bowing caused by the stress imbalance imparted by either other deposited coatings or the multilayer coating of the mask substrate. An film, such as TaSi, may be deposited on the front side and/or back of the low thermal expansion material before the material coating to balance the stress. The low thermal expansion material with a silicon overlayer and a silicon and/or other conductive underlayer enables improved defect inspection and stress balancing.

  6. Helium-Charged La-Ni-Al Thin Films Deposited by Magnetron Sputtering

    SciTech Connect

    Shi Liqun; Chen Deming; Xu Shilin; Liu Chaozhu; Hao Wanli; Zhou Zhuyin

    2005-07-15

    An advanced implantation of low energy helium-4 atoms during the La-Ni-Al film growth by adopting magnetron sputtering with Ar/He mixture gases is discussed. Both proton backscattering spectroscopy (PBS) and elastic recoil detection (ERD) analyses were adopted to measure helium concentration of the films and distribution in the near-surface region. Helium atoms with a high concentration incorporate evenly in deposited film. The introduction of the helium with no extra irradiation damage is expected by choosing suitable deposition conditions. It was found that amorphous and crystalline LaNi{sub 5}-type structures can be achieved when sputtered with pure Ar and Ar/He mixture gases at room temperature, respectively. Thermal desorption experiments proposes that a part of hydrogen atoms are bound to trapped helium at crystal and releases together with helium. Only a small fraction of helium is released from the helium-vacancy clusters in lower temperature range and most of helium is released from small size helium bubbles in the high temperature range.

  7. Accurate mask model for advanced nodes

    NASA Astrophysics Data System (ADS)

    Zine El Abidine, Nacer; Sundermann, Frank; Yesilada, Emek; Ndiaye, El Hadji Omar; Mishra, Kushlendra; Paninjath, Sankaranarayanan; Bork, Ingo; Buck, Peter; Toublan, Olivier; Schanen, Isabelle

    2014-07-01

    Standard OPC models consist of a physical optical model and an empirical resist model. The resist model compensates the optical model imprecision on top of modeling resist development. The optical model imprecision may result from mask topography effects and real mask information including mask ebeam writing and mask process contributions. For advanced technology nodes, significant progress has been made to model mask topography to improve optical model accuracy. However, mask information is difficult to decorrelate from standard OPC model. Our goal is to establish an accurate mask model through a dedicated calibration exercise. In this paper, we present a flow to calibrate an accurate mask enabling its implementation. The study covers the different effects that should be embedded in the mask model as well as the experiment required to model them.

  8. Informational masking and musical training

    NASA Astrophysics Data System (ADS)

    Oxenham, Andrew J.; Fligor, Brian J.; Mason, Christine R.; Kidd, Gerald

    2003-09-01

    The relationship between musical training and informational masking was studied for 24 young adult listeners with normal hearing. The listeners were divided into two groups based on musical training. In one group, the listeners had little or no musical training; the other group was comprised of highly trained, currently active musicians. The hypothesis was that musicians may be less susceptible to informational masking, which is thought to reflect central, rather than peripheral, limitations on the processing of sound. Masked thresholds were measured in two conditions, similar to those used by Kidd et al. [J. Acoust. Soc. Am. 95, 3475-3480 (1994)]. In both conditions the signal was comprised of a series of repeated tone bursts at 1 kHz. The masker was comprised of a series of multitone bursts, gated with the signal. In one condition the frequencies of the masker were selected randomly for each burst; in the other condition the masker frequencies were selected randomly for the first burst of each interval and then remained constant throughout the interval. The difference in thresholds between the two conditions was taken as a measure of informational masking. Frequency selectivity, using the notched-noise method, was also estimated in the two groups. The results showed no difference in frequency selectivity between the two groups, but showed a large and significant difference in the amount of informational masking between musically trained and untrained listeners. This informational masking task, which requires no knowledge specific to musical training (such as note or interval names) and is generally not susceptible to systematic short- or medium-term training effects, may provide a basis for further studies of analytic listening abilities in different populations.

  9. Psychometric functions for informational masking

    NASA Astrophysics Data System (ADS)

    Lutfi, Robert A.; Kistler, Doris J.; Callahan, Michael R.; Wightman, Frederic L.

    2003-12-01

    The term informational masking has traditionally been used to refer to elevations in signal threshold resulting from masker uncertainty. In the present study, the method of constant stimuli was used to obtain complete psychometric functions (PFs) from 44 normal-hearing listeners in conditions known to produce varying amounts of informational masking. The listener's task was to detect a pure-tone signal in the presence of a broadband noise masker (low masker uncertainty) and in the presence of multitone maskers with frequencies and amplitudes that varied at random from one presentation to the next (high masker uncertainty). Relative to the broadband noise condition, significant reductions were observed in both the slope and the upper asymptote of the PF for multitone maskers producing large amounts of informational masking. Slope was affected more for some listeners and conditions while asymptote was affected more for others; consequently, neither parameter alone was highly predictive of individual thresholds or the amount of informational masking. Mean slopes and asymptotes varied nonmonotonically with the number of masker components in a manner similar to mean thresholds, particularly when the estimated effect of energetic masking on thresholds was subtracted out. As in past studies, the threshold data were well described by a model in which trial-by-trial judgments are based on a weighted sum of levels in dB at the output of independent auditory filters. The psychometric data, however, complicated the model's interpretation in two ways: First, they suggested that, depending on the listener and condition, the weights can either reflect a fixed influence of masker components on each trial or the effect of occasionally mistaking a masker component for the signal from trial to trial. Second, they indicated that in either case the variance of the underlying decision variable as estimated from PF slope is not by itself great enough to account for the observed changes

  10. Helium-refrigeration system

    SciTech Connect

    Specht, J.R.; Millar, B.; Sutherland, A.

    1995-08-01

    The design, procurement, and preliminary construction was completed for adding two more wet expansion engines to two helium refrigerators. These will be added in mid-year FY 1995. In addition a variable speed drive will be added to an existing helium compressor. This is part of an energy conservation upgrade project to reduce operating costs from the use of electricity and liquid nitrogen. This project involves the replacement of Joule-Thompson valves in the refrigerators with expansion engines resulting in system efficiency improvements of about 30% and improved system reliability.

  11. Is solid helium a supersolid?

    SciTech Connect

    Hallock, Robert

    2015-05-15

    Recent experiments suggest that helium-4 atoms can flow through an experimental cell filled with solid helium. But that incompletely understood flow is quite different from the reported superfluid-like motion that so excited physicists a decade ago.

  12. Self-masking subtraction tomosynthesis

    SciTech Connect

    Chakraborty, D.P.; Yester, M.V.; Barnes, G.T.; Lakshminarayanan, A.V.

    1984-01-01

    The authors tested the image quality and dose savings of self-masking subtraction tomosynthesis (SST), which combines digital tomosynthesis with subtraction of a blurred self-mask. High-quality images of the inner ear of a head phantom were obtained at moderate dose savings. Although they were taken with linear motion, they did not exhibit the streaking due to off-fulcrum objects that is characteristic of conventional linear tomography. SST could reduce patient dose by a factor of at least 12 in examinations of the inner ear, and the mechanical aspects can be implemented with moderate modifications of existing instrumentation.

  13. Cochlear Implants

    MedlinePlus

    ... electrodes are inserted. The electronic device at the base of the electrode array is then placed under ... FDA approval for implants The Food and Drug Administration (FDA) regulates cochlear implant devices for both adults ...

  14. Goserelin Implant

    MedlinePlus

    Goserelin implant is used in combination with radiation therapy and other medications to treat localized prostate cancer and is ... treatment of abnormal bleeding of the uterus. Goserelin implant is in a class of medications called gonadotropin- ...

  15. Cochlear Implants

    MedlinePlus

    A cochlear implant is a small, complex electronic device that can help to provide a sense of sound. People who are ... of-hearing can get help from them. The implant consists of two parts. One part sits on ...

  16. Carmustine Implant

    MedlinePlus

    Carmustine implant is used along with surgery and sometimes radiation therapy to treat malignant glioma (a certain type of ... Carmustine implant comes as a small wafer that is placed in the brain by a doctor during surgery to ...

  17. Breast Implants

    MedlinePlus

    ... Updated Safety Information (Consumer Article) FDA Provides Updated Safety Data on Silicone Gel-Filled Breast Implants (Press Announcement) [ARCHIVED] Breast Implant Guidance for Industry (2006) Post Approval Studies Webpage Freedom of Information ...

  18. Cochlear implant

    MedlinePlus

    ... antenna. This part of the implant receives the sound, converts the sound into an electrical signal, and sends it to ... implants allow deaf people to receive and process sounds and speech. However, these devices do not restore ...

  19. The Kaonic Helium Case

    NASA Astrophysics Data System (ADS)

    Curceanu (Petrascu), C.; Bragadireanu, A. M.; Curceanu (Petrascu), C.; Ghio, F.; Girolami, B.; Guaraldo, C.; Iliescu, M.; Levi Sandri, P.; Lucherini, V.; Sirghi, D. L.; Sirghi, F.; Cargnelli, M.; Fuhrmann, H.; Ishiwatari, T.; Kienle, P.; Marton, J.; Zmeskal, J.; Fiorini, C.; Longoni, A.; Frizzi, T.; Itahashi, K.; Iwasaki, M.; Koike, T.; Ponta, T.; Soltau, H.; Lechner, P.; Struder, L.

    2005-12-01

    The only three existent kaonic helium X-ray transition measurements at present are referring to the transitions to 2p level. These measurements are more than 30 years old and the obtained results, affected by big errors, are much larger than those predicted by optical models. It is thought that the optical model is inadequate, due to the presence of the ∧(1405) resonance, not properly taken into account. Because the nucleons in the helium nucleus are tightly bound, the effective energy of the K-p interaction (1432 MeV at threshold) is in helium much closer to the energy of the resonance than in other nuclei. It is then planned to measure the kaonic helium X-ray transitions to the 2p level in the framework of the SIDDHARTA (SIlicon Drift Detector for Hadronic Atom Research by Timing Application) experiment, at the DAΦNE collider of Frascati National Laboratories, and to confirm or not the discrepancy reported by the previous experiments with a much smaller error.

  20. On Helium Anions in Helium Droplets: Interpreting Recent Experiments

    NASA Astrophysics Data System (ADS)

    Mauracher, Andreas; Huber, Stefan E.

    2014-10-01

    Helium droplets provide an ideal environment to study elementary processes in atomic systems at very low temperatures. Here, we discuss properties of charged and neutral, atomic and molecular helium species formed in helium droplets upon electron impact. By studying their interaction with atomic ground state helium we find that He, He2 and excited (metastable) He*- are well bound within the helium droplet. In comparison, He* , He2* and He2* are found to be squeezed out due to energetic reasons. We also present the formation pathways of atomic and molecular helium anions in helium droplets. Transition barriers in the energetic lowest He*- - He interaction potentials prevent molecule formation at the extremely low temperatures in helium droplets. In contrast, some excited states allow a barrier-free formation of molecular helium (anions). With these theoretical results at hand we can interpret recent experiments in which the resonant formation of atomic and molecular helium anions was observed. Furthermore, we give an outlook on the implications of the presence of these anionic species in doped helium droplets with regard to charge transfer reactions. Austrian Fund Agency (FWF, I 978-N20, DK+ project Computational Interdisciplinary Modelling W1227-N16)/Austrian Ministry of Science (BMWF, Konjunkturpaket II, UniInfrastrukturprogramm of the Focal Point Scientific Computing).

  1. Cost-effective mask-sharing technology for SOI LIGBT and PLDMOS

    NASA Astrophysics Data System (ADS)

    Huang, Yong; Qiao, Ming; Zhou, Xin; Liang, Tao; Li, Yang; Li, Zhaoji; Zhang, Bo

    2016-04-01

    Cost-effective mask-sharing technology for the 200 V silicon-on-insulator (SOI) lateral insulated gate bipolar transistor (LIGBT) and p-channel lateral double-diffused MOS (PLDMOS) are proposed in this paper. N-well and P-body implantations are shared as an N-buffer implantation of the LIGBT and P-buffer implantation of the PLDMOS, respectively, which reduces two masks compared with the conventional process. The structure and process parameters for LIGBT and PLDMOS with the new process are optimized by simulation to achieve good performance. The experimental results indicate that the LIGBT and PLDMOS using the new process maintain the same performance compared to the conventional devices.

  2. Multiple-mask chemical etching

    NASA Technical Reports Server (NTRS)

    Cannon, D. L.

    1969-01-01

    Multiple masking techniques use lateral etching to reduce the total area of the high etch-rate oxide exposed to the chemical etchant. One method uses a short-term etch to remove the top layer from the silicon oxide surface, another acts before the top layer is grown.

  3. Factors affecting speech understanding in gated interference: Cochlear implant users and normal-hearing listeners

    NASA Astrophysics Data System (ADS)

    Nelson, Peggy B.; Jin, Su-Hyun

    2004-05-01

    Previous work [Nelson, Jin, Carney, and Nelson (2003), J. Acoust. Soc. Am 113, 961-968] suggested that cochlear implant users do not benefit from masking release when listening in modulated noise. The previous findings indicated that implant users experience little to no release from masking when identifying sentences in speech-shaped noise, regardless of the modulation frequency applied to the noise. The lack of masking release occurred for all implant subjects who were using three different devices and speech processing strategies. In the present study, possible causes of this reduced masking release in implant listeners were investigated. Normal-hearing listeners, implant users, and normal-hearing listeners presented with a four-band simulation of a cochlear implant were tested for their understanding of sentences in gated noise (1-32 Hz gate frequencies) when the duty cycle of the noise was varied from 25% to 75%. No systematic effect of noise duty cycle on implant and simulation listeners' performance was noted, indicating that the masking caused by gated noise is not only energetic masking. Masking release significantly increased when the number of spectral channels was increased from 4 to 12 for simulation listeners, suggesting that spectral resolution is important for masking release. Listeners were also tested for their understanding of gated sentences (sentences in quiet interrupted by periods of silence ranging from 1 to 32 Hz as a measure of auditory fusion, or the ability to integrate speech across temporal gaps. Implant and simulation listeners had significant difficulty understanding gated sentences at every gate frequency. When the number of spectral channels was increased for simulation listeners, their ability to understand gated sentences improved significantly. Findings suggest that implant listeners' difficulty understanding speech in modulated conditions is related to at least two (possibly related) factors: degraded spectral information and

  4. "The Mask Who Wasn't There": Visual Masking Effect with the Perceptual Absence of the Mask

    ERIC Educational Resources Information Center

    Rey, Amandine Eve; Riou, Benoit; Muller, Dominique; Dabic, Stéphanie; Versace, Rémy

    2015-01-01

    Does a visual mask need to be perceptually present to disrupt processing? In the present research, we proposed to explore the link between perceptual and memory mechanisms by demonstrating that a typical sensory phenomenon (visual masking) can be replicated at a memory level. Experiment 1 highlighted an interference effect of a visual mask on the…

  5. Helium anion formation inside helium droplets

    NASA Astrophysics Data System (ADS)

    Jabbour Al Maalouf, Elias; Reitshammer, Julia; Ribar, Anita; Scheier, Paul; Denifl, Stephan

    2016-07-01

    The formation of He∗- is examined with improved electron energy resolution of about 100 meV utilizing a hemispherical electron monochromator. The work presented provides a precise determination of the three previously determined resonance peak positions that significantly contribute to the formation of He∗- inside helium nanodroplets in the energy range from 20 eV to 29.5 eV. In addition, a new feature is identified located at 27.69 ± 0.18 eV that we assign to the presence of O2 as a dopant inside the droplet. With increasing droplet size a small blue shift of the resonance positions is observed. Also for the relatively low electron currents used in the present study (i.e., 15-70 nA) a quadratic dependence of the He∗- ion yield on the electron current is observed.

  6. Physiological functioning of the ear and masking

    NASA Technical Reports Server (NTRS)

    1984-01-01

    The physiological functions of the ear and the role masking plays in speech communication are examined. Topics under investigation include sound analysis of the ear, the aural reflex, and various types of noise masking.

  7. Effect of a high helium content on the flow and fracture properties of a 9Cr martensitic steel

    NASA Astrophysics Data System (ADS)

    Henry, J.; Vincent, L.; Averty, X.; Marini, B.; Jung, P.

    2007-08-01

    An experimental characterization was conducted of helium effects on the mechanical properties of a 9Cr martensitic steel. Six sub-size Charpy samples were implanted in the notch region at 250 °C with 0.25 at.% helium and subsequently tested in 3-point bending at room temperature. Brittle fracture mode (cleavage and intergranular fracture) was systematically observed in the implanted zones of the samples. Finite element calculations of the tests, using as input the tensile properties measured on a helium loaded sample, were performed in order to determine the fracture stress at the onset of brittle crack propagation. Preliminary TEM investigations of the implantation-induced microstructure revealed a high density of small helium bubbles.

  8. IBA studies of helium mobility in nuclear materials revisited

    NASA Astrophysics Data System (ADS)

    Trocellier, P.; Agarwal, S.; Miro, S.; Vaubaillon, S.; Leprêtre, F.; Serruys, Y.

    2015-12-01

    The aim of this paper is to point out and to discuss some features extracted from the study of helium migration in nuclear materials performed during the last fifteen years using ion beam analysis (IBA) measurements. The first part of this paper is devoted to a brief description of the two main IBA methods used, i.e. deuteron induced nuclear reaction for 3He depth profiling and high-energy heavy-ion induced elastic recoil detection analysis for 4He measurement. In the second part, we provide an overview of the different studies carried out on model nuclear waste matrices and model nuclear reactor structure materials in order to illustrate and discuss specific results in terms of key influence parameters in relation with thermal or radiation activated migration of helium. Finally, we show that among the key parameters we have investigated as able to influence the height of the helium migration barrier, the following can be considered as pertinent: the experimental conditions used to introduce helium (implanted ion energy and implantation fluence), the grain size of the matrix, the lattice cell volume, the Young's modulus, the ionicity degree of the chemical bond between the transition metal atom M and the non-metal atom X, and the width of the band gap.

  9. Mask qualification strategies in a wafer fab

    NASA Astrophysics Data System (ADS)

    Jaehnert, Carmen; Kunowski, Angela

    2007-02-01

    Having consistent high quality photo masks is one of the key factors in lithography in the wafer fab. Combined with stable exposure- and resist processes, it ensures yield increases in production and fast learning cycles for technology development and design evaluation. Preventive controlling of incoming masks and quality monitoring while using the mask in production is essential for the fab to avoid yield loss or technical problems caused by mask issues, which eventually result in delivery problems to the customer. In this paper an overview of the procedures used for mask qualification and production release, for both logic and DRAM, at Infineon Dresden is presented. Incoming qualification procedures, such as specification checks, incoming inspection, and inline litho process window evaluation, are described here. Pinching and electrical tests, including compatibility tests for mask copies for high volume products on optimized litho processes, are also explained. To avoid mask degradation over lifetime, re-inspection checks are done for re-qualification while using the mask in production. The necessity of mask incoming inspection and re-qualification, due to the repeater printing from either the processing defects of the original mask or degrading defects of being used in the fab (i.e. haze, ESD, and moving particles, etc.), is demonstrated. The need and impact of tight mask specifications, such as CD uniformity signatures and corresponding electrical results, are shown with examples of mask-wafer CD correlation.

  10. 21 CFR 868.5600 - Venturi mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Venturi mask. 868.5600 Section 868.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5600 Venturi mask. (a) Identification. A venturi mask is...

  11. 21 CFR 868.5600 - Venturi mask.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Venturi mask. 868.5600 Section 868.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5600 Venturi mask. (a) Identification. A venturi mask is...

  12. 21 CFR 868.5600 - Venturi mask.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Venturi mask. 868.5600 Section 868.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5600 Venturi mask. (a) Identification. A venturi mask is...

  13. 21 CFR 868.5600 - Venturi mask.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Venturi mask. 868.5600 Section 868.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5600 Venturi mask. (a) Identification. A venturi mask is...

  14. 21 CFR 868.5600 - Venturi mask.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Venturi mask. 868.5600 Section 868.5600 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5600 Venturi mask. (a) Identification. A venturi mask is...

  15. Masks: Escape to/from Reality.

    ERIC Educational Resources Information Center

    Kavett, Hyman

    1981-01-01

    Explains the significance of masks in ethnographic and cultural research and suggests 24 activities intended for use by social studies classroom teachers as they teach about masks. Activities include projecting slides onto students' bodies and faces, directing students to create masks from old clothing and rags, cutting faces from magazines, and…

  16. Method for mask repair using defect compensation

    DOEpatents

    Sweeney, Donald W.; Ray-Chaudhuri, Avijit K.

    2001-01-01

    A method for repair of amplitude and/or phase defects in lithographic masks. The method involves modifying or altering a portion of the absorber pattern on the surface of the mask blank proximate to the mask defect to compensate for the local disturbance (amplitude or phase) of the optical field due to the defect.

  17. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  18. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  19. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  20. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  1. 21 CFR 868.5580 - Oxygen mask.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and... ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device placed over a patient's nose, mouth, or tracheostomy to administer oxygen or aerosols. (b)...

  2. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... operating in the frequency bands governed under this part. Applicable Emission Masks Frequency band(MHz) Mask for equipment with Audio low passfilter Mask for equipment without audio low pass filter Below 25... the output power (P in watts) of the transmitter as follows: (1) On any frequency removed from...

  3. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... operating under this part. Applicable Emission Masks Frequency band (MHz) Mask for equipmentwith audio low pass filter Mask for equipmentwithout audio low pass filter Below 25 1 A or B A or C 25-50 B C 72-76 B... watts) of the transmitter as follows: (1) On any frequency removed from the assigned frequency by...

  4. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... operating in the frequency bands governed under this part. Applicable Emission Masks Frequency band(MHz) Mask for equipment with Audio low passfilter Mask for equipment without audio low pass filter Below 25... the output power (P in watts) of the transmitter as follows: (1) On any frequency removed from...

  5. 47 CFR 90.210 - Emission masks.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... operating under this part. Applicable Emission Masks Frequency band (MHz) Mask for equipmentwith audio low pass filter Mask for equipmentwithout audio low pass filter Below 25 1 A or B A or C 25-50 B C 72-76 B... watts) of the transmitter as follows: (1) On any frequency removed from the assigned frequency by...

  6. Object Substitution Masking Induced by Illusory Masks: Evidence for Higher Object-Level Locus of Interference

    ERIC Educational Resources Information Center

    Hirose, Nobuyuki; Osaka, Naoyuki

    2009-01-01

    A briefly presented target can be rendered invisible by a lingering sparse mask that does not even touch it. This form of visual backward masking, called object substitution masking, is thought to occur at the object level of processing. However, it remains unclear whether object-level interference alone produces substitution masking because…

  7. Performance of GFIS mask repair system for various mask materials

    NASA Astrophysics Data System (ADS)

    Aramaki, Fumio; Kozakai, Tomokazu; Matsuda, Osamu; Yasaka, Anto; Yoshikawa, Shingo; Kanno, Koichi; Miyashita, Hiroyuki; Hayashi, Naoya

    2014-10-01

    We have developed a new focused ion beam (FIB) technology using a gas field ion source (GFIS) for mask repair. Meanwhile, since current high-end photomasks do not have high durability in exposure nor cleaning, some new photomask materials are proposed. In 2012, we reported that our GFIS system had repaired a representative new material "A6L2". It is currently expected to extend the application range of GFIS technology for various new materials and various defect shapes. In this study, we repaired a single bridge, a triple bridge and a missing hole on a phase shift mask (PSM) of "A6L2", and also repaired single bridges on a binary mask of molybdenum silicide (MoSi) material "W4G" and a PSM of high transmittance material "SDC1". The etching selectivity between those new materials and quartz were over 4:1. There were no significant differences of pattern shapes on scanning electron microscopy (SEM) images between repair and non-repair regions. All the critical dimensions (CD) at repair regions were less than +/-3% of those at normal ones on an aerial image metrology system (AIMS). Those results demonstrated that GFIS technology is a reliable solution of repairing new material photomasks that are candidates for 1X nm generation.

  8. Spatially dependent cluster dynamics modeling of microstructure evolution in low energy helium irradiated tungsten

    NASA Astrophysics Data System (ADS)

    Faney, T.; Wirth, B. D.

    2014-09-01

    In fusion reactors, plasma facing components (PFC) and in particular the divertor will be irradiated with high fluxes of low energy (˜100 eV) helium and hydrogen ions. Tungsten is one of the leading candidate divertor materials for ITER and DEMO fusion reactors. However, the behavior of tungsten under high dose, coupled helium/hydrogen exposure remains to be fully understood. The PFC response and performance changes are intimately related to microstructural changes, such as the formation of point defect clusters, helium and hydrogen bubbles or dislocation loops. Computational materials modeling has been used to investigate the mechanisms controlling microstructural evolution in tungsten following high dose, high temperature helium exposure. The aim of this study is to understand and predict helium implantation, primary defect production and defect diffusion, helium-defect clustering and interactions below a tungsten surface exposed to low energy helium irradiation. The important defects include interstitial clusters, vacancy clusters, helium interstitials and helium-vacancy clusters. We report results from a one-dimensional, spatially dependent cluster dynamics model based on the continuum reaction-diffusion rate theory to describe the evolution in space and time of all these defects. The key parameter inputs to the model (diffusion coefficients, migration and binding energies, initial defect production) are determined from a combination of atomistic materials modeling and available experimental data.

  9. Mask blank defect printability comparison using optical and SEM mask and wafer inspection and bright field actinic mask imaging

    NASA Astrophysics Data System (ADS)

    Mangat, Pawitter; Verduijn, Erik; Wood, Obert R.; Benk, Markus P.; Wojdyla, Antoine; Goldberg, Kenneth A.

    2015-07-01

    Despite significant enhancements in defect detection using optical and e-beam methodology, the smaller length scales and increasing challenges of future technology nodes motivate ongoing research into the need and associated cost of actinic inspection for EUV masks. This paper reports an extensive study of two EUV patterned masks, wherein the mask blank defectivity was characterized using optical (mask and wafer) methods and bright-field mask imaging (using the SHARP actinic microscope) of previously identified blank defects. We find that the bright field actinic imaging tool microscope captures and images many defects that are not seen by the automated optical inspection of patterned masks and printed wafers. In addition, actinic review reveals the impact of multilayer damage and depicts the printability profile which can be used as an added metric to define the patterned mask repair and defect compensation strategies.

  10. Aperture masking behind AO systems

    NASA Astrophysics Data System (ADS)

    Ireland, Michael J.

    2012-07-01

    Sparse Aperture-Mask Interferometry (SAM or NRM) behind Adaptive Optics (AO) has now come of age, with more than a dozen astronomy papers published from several 5-10m class telescopes around the world. I will describe the reasons behind its success in achieving relatively high contrasts ( 1000:1 at lambda/ D) and repeatable binary astronomy at the diffraction limit, even when used behind laser-guide star adaptive optics. Placed within the context of AO calibration, the information in an image can be split into pupil-plane phase, Fourier amplitude and closure-phase. It is the closure-phase observable, or its generalisation to Kernel phase, that is immune to pupil-plane phase errors at first and second-order and has been the reason for the technique's success. I will outline the limitations of the technique and the prospects for aperture-masking and related techniques in the future.

  11. Implantable Microimagers

    PubMed Central

    Ng, David C.; Tokuda, Takashi; Shiosaka, Sadao; Tano, Yasuo; Ohta, Jun

    2008-01-01

    Implantable devices such as cardiac pacemakers, drug-delivery systems, and defibrillators have had a tremendous impact on the quality of live for many disabled people. To date, many devices have been developed for implantation into various parts of the human body. In this paper, we focus on devices implanted in the head. In particular, we describe the technologies necessary to create implantable microimagers. Design, fabrication, and implementation issues are discussed vis-à-vis two examples of implantable microimagers; the retinal prosthesis and in vivo neuro-microimager. Testing of these devices in animals verify the use of the microimagers in the implanted state. We believe that further advancement of these devices will lead to the development of a new method for medical and scientific applications.

  12. Applications of Groundwater Helium

    USGS Publications Warehouse

    Kulongoski, Justin T.; Hilton, David R.

    2011-01-01

    Helium abundance and isotope variations have widespread application in groundwater-related studies. This stems from the inert nature of this noble gas and the fact that its two isotopes ? helium-3 and helium-4 ? have distinct origins and vary widely in different terrestrial reservoirs. These attributes allow He concentrations and 3He/4He isotope ratios to be used to recognize and quantify the influence of a number of potential contributors to the total He budget of a groundwater sample. These are atmospheric components, such as air-equilibrated and air-entrained He, as well as terrigenic components, including in situ (aquifer) He, deep crustal and/or mantle He and tritiogenic 3He. Each of these components can be exploited to reveal information on a number of topics, from groundwater chronology, through degassing of the Earth?s crust to the role of faults in the transfer of mantle-derived volatiles to the surface. In this review, we present a guide to how groundwater He is collected from aquifer systems and quantitatively measured in the laboratory. We then illustrate the approach of resolving the measured He characteristics into its component structures using assumptions of endmember compositions. This is followed by a discussion of the application of groundwater He to the types of topics mentioned above using case studies from aquifers in California and Australia. Finally, we present possible future research directions involving dissolved He in groundwater.

  13. Improving vision by pupil masking.

    PubMed

    Bonaque-González, Sergio; Ríos-Rodríguez, Susana; López-Gil, Norberto

    2016-07-01

    We propose an alternative solution to improve visual quality by spatially modulating the amplitude of light passing into the eye (related to the eye's transmittance), in contrast to traditional correction of the wavefront phase (related to the local refractive power). Numerical simulations show that masking the aberrated areas at the pupil plane should enhance visual function, especially in highly aberrated eyes. This correction could be implemented in practice using customized contact or intraocular lenses. PMID:27446688

  14. Improving vision by pupil masking

    PubMed Central

    Bonaque-González, Sergio; Ríos-Rodríguez, Susana; López-Gil, Norberto

    2016-01-01

    We propose an alternative solution to improve visual quality by spatially modulating the amplitude of light passing into the eye (related to the eye's transmittance), in contrast to traditional correction of the wavefront phase (related to the local refractive power). Numerical simulations show that masking the aberrated areas at the pupil plane should enhance visual function, especially in highly aberrated eyes. This correction could be implemented in practice using customized contact or intraocular lenses. PMID:27446688

  15. High Productivity Implantation ''PARTIAL IMPLANT''

    SciTech Connect

    Hino, Masayoshi; Miyamoto, Naoki; Sakai, Shigeki; Matsumoto, Takao

    2008-11-03

    The patterned ion implantation 'PARTIAL IMPLANT' has been developed as a productivity improvement tool. The Partial Implant can form several different ion dose areas on the wafer surface by controlling the speed of wafer moving and the stepwise rotation of twist axis. The Partial Implant system contains two implant methods. One method is 'DIVIDE PARTIAL IMPLANT', that is aimed at reducing the consumption of the wafer. The Divide Partial Implant evenly divides dose area on one wafer surface into two or three different dose part. Any dose can be selected in each area. So the consumption of the wafer for experimental implantation can be reduced. The second method is 'RING PARTIAL IMPLANT' that is aimed at improving yield by correcting electrical characteristic of devices. The Ring Partial Implant can form concentric ion dose areas. The dose of wafer external area can be selected to be within plus or minus 30% of dose of wafer central area. So the electrical characteristic of devices can be corrected by controlling dose at edge side on the wafer.

  16. Mask pattern generator employing EPL technology

    NASA Astrophysics Data System (ADS)

    Yoshioka, Nobuyuki; Yamabe, Masaki; Wakamiya, Wataru; Endo, Nobuhiro

    2003-08-01

    Mask cost is one of crucial issues in device fabrication, especially in SoC (System on a Chip) with small-volume production. The cost mainly depends on productivity of mask manufacturing tools such as mask writers and defect inspection tools. EPL (Electron Projection Lithography) has been developing as a high-throughput electron beam exposure technology that will succeed optical lithography. The application of EPL technology to mask writing will result in high productivity and contribute to decrease the mask cost. The concept of a mask pattern generator employing EPL technology is proposed in this paper. It is very similar to EPL technology used for pattern printing on a wafer. The mask patterns on the glass substrate are exposed by projecting the basic circuit patterns formed on the mother EPL mask. One example of the mother EPL mask is a stencil type made with 200-mm Si wafer. The basic circuit patterns are IP patterns and logical primitive patterns such as cell libraries (AND, OR, Inverter, Flip-Flop and etc.) to express the SoC device patterns. Since the SoC patterns are exposed with its collective units such as IP and logical primitive patterns by using this method, the high throughput will be expected comparing with conventional mask E-beam writers. In this paper, the mask pattern generator with the EPL technology is proposed. The concept, its advantages and issues to be solved are discussed.

  17. Process capability of etched multilayer EUV mask

    NASA Astrophysics Data System (ADS)

    Takai, Kosuke; Iida nee Sakurai, Noriko; Kamo, Takashi; Morikawa, Yasutaka; Hayashi, Naoya

    2015-10-01

    With shrinking pattern size at 0.33NA EUV lithography systems, mask 3D effects are expected to become stronger, such as horizontal/vertical shadowing, best focus shifts through pitch and pattern shift through focus. Etched multilayer EUV mask structures have been proposed in order to reduce mask 3D effects. It is estimated that etched multilayer type mask is also effective in reducing mask 3D effects at 0.33NA with lithographic simulation, and it is experimentally demonstrated with NXE3300 EUV Lithography system. We obtained cross-sectional TEM image of etched multilayer EUV mask pattern. It is observed that patterned multilayer width differs from pattern physical width. This means that effective reflecting width of etched multilayer pattern is smaller than pattern width measured by CD-SEM. In this work, we evaluate mask durability against both chemical and physical cleaning process to check the feasibility of etched multilayer EUV mask patterning against mask cleaning for 0.33NA EUV extension. As a result, effective width can be controlled by suitable cleaning chemicals because sidewall film works as a passivation film. And line and space pattern collapse is not detected by DUV mask pattern inspection tool after mask physical cleaning that includes both megasonic and binary spray steps with sufficient particle removal efficiency.

  18. Helium anion formation inside helium droplets

    NASA Astrophysics Data System (ADS)

    Maalouf, Elias Jabbour Al; Reitshammer, Julia; Ribar, Anita; Scheier, Paul; Denifl, Stephan

    2016-07-01

    The formation of He∗- is examined with improved electron energy resolution of about 100 meV utilizing a hemispherical electron monochromator. The work presented provides a precise determination of the three previously determined resonance peak positions that significantly contribute to the formation of He∗- inside helium nanodroplets in the energy range from 20 eV to 29.5 eV. In addition, a new feature is identified located at 27.69 ± 0.18 eV that we assign to the presence of O2 as a dopant inside the droplet. With increasing droplet size a small blue shift of the resonance positions is observed. Also for the relatively low electron currents used in the present study (i.e., 15-70 nA) a quadratic dependence of the He∗- ion yield on the electron current is observed. Contribution to the Topical Issue "Advances in Positron and Electron Scattering", edited by Paulo Limao-Vieira, Gustavo Garcia, E. Krishnakumar, James Sullivan, Hajime Tanuma and Zoran Petrovic.

  19. Cortical correlate of pattern backward masking.

    PubMed Central

    Kovács, G; Vogels, R; Orban, G A

    1995-01-01

    The perception of a briefly presented shape is strongly impaired when it is followed by another pattern, a phenomenon called backward masking. We found that the vast majority of a sample of shape-selective neurons in the macaque inferior temporal cortex respond selectively to backward-masked shapes, although these shapes could not be discriminated by human and monkey subjects. However, this selective response was brief, since it was either interrupted by the mask or overridden by a response to the mask itself. We show that reliable discrimination of briefly presented shapes by single neurons depends on the temporal integration of the response. Presentation of the mask, however, reduces the number of spikes available for integration, explaining backward masking. These results also provide direct neurophysiological evidence for the "interruption theory" of backward masking. PMID:7777553

  20. History and future of mask making

    NASA Astrophysics Data System (ADS)

    Levy, Ken L.

    1996-12-01

    The history of the mask industry has three main periods, which I call the Classical Period, the Dark Ages, and the Renaissance, by analogy with those periods in the history of Western Europe. During the Classical Period, people developed 1X masks and the technology to make them. In the Dark Ages, people exploited the equipment developed during the Classical Period to make 5X reduction reticle, ending the nobility of mask making. In today's Renaissance of mask making, a proliferation of mask types is requiring a rebirth of innovation and creativity. The Renaissance resembles the Classical Period: masks are once again strategic, and technological capability is once again the driver. Meanwhile, the mask industry is carrying forward the productivity and efficiency gains it achieved during the Dark Ages. We must create a new business and economic model to support these changes in the characteristics of the marketplace.

  1. 42 CFR 84.110 - Gas masks; description.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... as follows: (1) Front-mounted or back-mounted gas mask. A gas mask which consists of a full facepiece.... (2) Chin-style gas mask. A gas mask which consists of a full facepiece, a canister which is usually attached to the facepiece, and associated connections. (3) Escape gas mask. A gas mask designed for...

  2. Fabrication and commercialization of scalpel masks

    NASA Astrophysics Data System (ADS)

    Novembre, Anthony E.; Peabody, Milton L., Jr.; Blakey, Myrtle I.; Farrow, Reginald C.; Kasica, Richard J.; Liddle, James A.; Saunders, Thomas E.; Tennant, Donald M.

    1998-09-01

    SCALPEL masks have been fabricated for use in the Proof-of- Lithography system and to demonstrate the feasibility of having them produced by a commercial blank manufacturer and optical mask shops. Masks blanks are formed from 100 mm diameter silicon wafers. A 100-150 nm thick SiNx layer is LPCVD deposited onto the wafers followed by magnetron sputter deposition of a thin Cr/W metal layer which is used as the scatterer layer for the mask>the mask is supported by an underlying network of struts which are arranged to be compatible with the step and scan writing strategy of the exposure tool and to provide robustness to the mask. Crystallographic wet etching of the silicon wafer forms membranes and struts. To date over 300 mask blanks have been formed and yield data as a function of the thickness of the silicon nitride membrane has been quantified. Recent developments in the mask blank formation process include the production of blanks by MCNC who serve as a commercial source of SCALPEL mask blanks. They have successfully delivered 36 blanks that exhibit equivalent properties to those produced at Lucent. Mask patterning has been performed at the commercial optical mask shops of PHOTRONICS and DUPONT. In this investigation a MEBES exposure system has been used to write patterns. The resist used is ZEP-520 and development and pattern transfer processes are performed in the STEAG-Hammatech spray/spin processing tool. Metrology is performed using a KMS 310 RT optical microscope. Pattern placement accuracy is measured on the LMS 2020 system without modification. The masks are inspected for defects using the optical based KLA 300 series inspection system in a die to die mode and in transmission. Results to date suggest feasibility of producing SCALPEL masks by a commercial blank supplier and by merchant optical mask shops.

  3. Comparative Study of Manufacturing Techniques for Coronagraphic Binary Pupil Masks: Masks on Substrates and Free-Standing Masks

    NASA Astrophysics Data System (ADS)

    Enya, Keigo; Haze, Kanae; Kotani, Takayuki; Abe, Lyu

    2012-12-01

    We present a comparative study of the manufacture of binary pupil masks for coronagraphic observations of exoplanets. A checkerboard mask design, a type of binary pupil mask design, was adopted, and identical patterns of the same size were used for all masks in order that we could compare the differences resulting from the different manufacturing methods. The masks on substrates had aluminum checkerboard patterns with thicknesses of 0.1/0.2/0.4/0.8/1.6μm, constructed on substrates of BK7 glass, silicon, and germanium using photolithography and chemical processes. Free-standing masks made of copper and nickel with thicknesses of 2/5/10/20μm were also realized using photolithography and chemical processes, which included careful release from the substrate used as an intermediate step in the manufacture. Coronagraphic experiments using a visible laser were carried out for all masks on BK7 glass substrate and the free-standing masks. The average contrasts were 8.4 × 10-8, 1.2 × 10-7, and 1.2 × 10-7 for the masks on BK7 substrates, the free-standing copper masks, and the free-standing nickel masks, respectively. No significant correlation was concluded between the contrast and the mask properties. The high-contrast masks have the potential to cover the needs of coronagraphs for both ground-based and space-borne telescopes over a wide wavelength range. Especially, their application to the infrared space telescope, SPICA, is appropriate.

  4. Particle Contamination Control Technology in Electron Beam Mask Writing System for Next-Generation Mask Fabrication

    NASA Astrophysics Data System (ADS)

    Akeno, Kiminobu; Ogasawara, Munehiro; Ooki, Kenji; Tojo, Toru; Hirano, Ryoichi; Yoshitake, Shusuke; Toriumi, Masaki; Sekine, Akihiko; Takigawa, Tadahiko; Shinoda, Toshiki; Noguchi, Shigeru

    2002-09-01

    An in-situ measurement system for particles in an electron beam (EB) writer is developed to improve mask yield management. The system has satisfied the required installation specifications for a mask blank inspection system for the EB writer, and the results of an experiment using the system prove that particles added from the mask handling system in our EB writer satisfy the total particle count specification (<1.25 counts/cycle for 6 inch mask). The investigation of particle increase after repeated mask movement has been carried out in each segmented mask handling route. It has been clarified that the segmentation test using this system is helpful for investigation of the origin of particle production on a mask. Effective application of information such as particle position and size obtained by this system will be very useful for improving mask yield management in the mask fabrication process in terms of pattern inspection and repair system.

  5. High performance mask fabrication process for the next-generation mask production

    NASA Astrophysics Data System (ADS)

    Yagawa, Keisuke; Ugajin, Kunihiro; Suenaga, Machiko; Kobayashi, Yoshihito; Motokawa, Takeharu; Hagihara, Kazuki; Saito, Masato; Itoh, Masamitsu

    2014-07-01

    ArF immersion lithography combined with double patterning has been used for fabricating below half pitch 40nm devices. However, when pattern size shrinks below 20nm, we must use new technology like quadruple patterning process or next generation lithography (NGL) solutions. Moreover, with change in lithography tool, next generation mask production will be needed. According to ITRS 2013, fabrication of finer patterns less than 15nm will be required on mask plate in NGL mask production 5 years later [1]. In order to fabricate finer patterns on mask, higher resolution EB mask writer and high performance fabrication process will be required. In a previous study, we investigated a potential of mask fabrication process for finer patterning and achieved 17nm dense line pattern on mask plate by using VSB (Variable Shaped Beam) type EB mask writer and chemically amplified resist [2][3]. After a further investigation, we constructed higher performance mask process by using new EB mask writer EBM9000. EBM9000 is the equipment supporting hp16nm generation's photomask production and has high accuracy and high throughput. As a result, we achieved 15.5nm pattern on mask with high productivity. Moreover, from evaluation of isolated pattern, we proved that current mask process has the capability for sub-10nm pattern. These results show that the performance of current mask fabrication process have the potential to fabricate the next-generation mask.

  6. Helium jet dispersion to atmosphere

    NASA Astrophysics Data System (ADS)

    Khan, Hasna J.

    On the event of loss of vacuum guard of superinsulated helium dewar, high rate of heat transfer into the tank occurs. The rapid boiling of liquid helium causes the burst disk to rupture at four atmospheres and consequently the helium passes to the atmosphere through vent lines. The gaseous helium forms a vertical buoyant jet as it exits the vent line into a stagnant environment. Characterization of the gaseous jet is achieved by detailed analysis of the axial and radial dependence of the flow parameters.

  7. Helium cryopumping for fusion applications

    SciTech Connect

    Sedgley, D.W.; Batzer, T.H.; Call, W.R.

    1988-05-01

    Large quantities of helium and hydrogen isotopes will be exhausted continuously from fusion power reactors. This paper summarizes two development programs undertaken to address vacuum pumping for this application: (i) A continuous duty cryopump for pumping helium and/or hydrogen species using charcoal sorbent and (ii) a cryopump configuration with an alternative shielding arrangement using charcoal sorbent or argon spray. A test program evaluated automatic pumping of helium, helium pumping by charcoal cryosorption and with argon spray, and cryosorption of helium/hydrogen mixtures. The continuous duty cryopump pumped helium continuously and conveniently. Helium pumping speed was 7.7 l/s/cm/sup 2/ of charcoal, compared to 5.8 l/s/cm/sup 2/ for the alternative pump. Helium speed using argon spray was 18% of that obtained by charcoal cryosorption in the same (W-panel) pump. During continuous duty cryopump mixture tests with helium and hydrogen copumped on charcoal, gas was released sporadically. Testing was insufficient to explain this unacceptable event.

  8. [Implant allergies].

    PubMed

    Thomas, P; Thomsen, M

    2010-03-01

    An increasing number of patients receive and benefit from osteosynthesis materials or artificial joint replacement. The most common complications are mechanical problems or infection. Metals like nickel, chromium and cobalt as well as bone cement components like acrylates and gentamicin are potential contact allergens which can cause intolerance reactions to implants. Eczema, delayed wound/bone healing, recurrent effusions, pain and implant loosening all have been described as manifestation of implant allergy. In contrast to the high incidence of cutaneous metal allergy, allergies associated with implants are rare. Diagnosis of metal implant allergy is still difficult. Thus differential diagnoses--in particular infection--have to be excluded and a combined approach of allergologic diagnostics by patch test and histopathology of peri-implant tissue is recommended. It is still unknown which conditions induce allergic sensitization to implants or trigger peri-implant allergic reactions in the case of preexisting cutaneous metal allergy. Despite the risk of developing complications being unclear, titanium based osteosynthesis materials are recommended for metal allergic patients and the use of metal-metal couplings in arthroplasty is not recommended for such patients. If the regular CoCr-polyethylene articulation is employed, the patient should give informed written consent. PMID:20204719

  9. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2002) (a)...

  10. 48 CFR 52.208-8 - Required Sources for Helium and Helium Usage Data.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... Helium and Helium Usage Data. 52.208-8 Section 52.208-8 Federal Acquisition Regulations System FEDERAL... Provisions and Clauses 52.208-8 Required Sources for Helium and Helium Usage Data. As prescribed in 8.505, insert the following clause: Required Sources for Helium and Helium Usage Data (APR 2014) (a)...