The effect of rapid thermal annealing （RTA） ambient on denuded zone and oxygen precipitates in Czochralski （CZ） silicon wafers is studied in this paper. N2 and a N2/NH3 mixture are used as RTA ambient. It is demon...The effect of rapid thermal annealing （RTA） ambient on denuded zone and oxygen precipitates in Czochralski （CZ） silicon wafers is studied in this paper. N2 and a N2/NH3 mixture are used as RTA ambient. It is demonstrated that a high density of oxygen precipitates and thin denuded zone are obtained in N2/NH3 ambient,while a relatively lower density of oxygen precipitates and thicker denuded zone are observed in N2 ambient. As the RTA duration times increased, the oxygen precipitate density increased and the denuded zone depth decreased. X-ray photoelectron spectroscopy （XPS） data and atomic force microscope （AFM） results show that there RTA process,which can explain the different effect of RTA was a surface nitriding reaction during the N2/NH3 ambient ambient.展开更多
The precipitation and gettering behaviors of copper （Cu） at different defective regions in multicrystalline silicon were investigated by combining scanning infrared microscopy, optical microscopy, inductively couple...The precipitation and gettering behaviors of copper （Cu） at different defective regions in multicrystalline silicon were investigated by combining scanning infrared microscopy, optical microscopy, inductively coupled plasma mass spectrometry and microwave photo-conductance decay. It is found that the behaviors of Cu precipitation are strongly dependent on the defect density. Most of the Cu contaminants tend to form precipitates homogeneously in the low density defect region, while they mostly segregate at the defects and form precipitates heterogeneously in the high density defect region. In the case of heavy contamination, the Cu precipitate can significantly reduce the carrier lifetime of multicrystalline silicon due to their Schottkydiode behavior in the silicon substrate. A 900 °C rap thermal process （RTP） phosphorus gettering anneal cannot be sufficiently effective to remove the Cu precipitates in these two regions.展开更多
The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process ...The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it attains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions （from 500-750℃）.展开更多
In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and hig...In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature（HPHT） by using the temperature gradient method（TGM）, with adopting Ti/Cu as the nitrogen getter in Ni70Mn25Co5（abbreviated as NiMnCo） or Fe（55）Ni（29）Co（16）（abbreviated FeNiCo） catalyst. The values of nitrogen concentration（Nc） in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo or Ti/Cu（1.8 wt%） is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-Ⅱa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo catalyst.展开更多
Ti-Mo getters have been fabricated via metal injection molding (MIM) using three kinds of Ti powders with different mean particle sizes of 46 μm,35 μm and 26 μm,respectively. The surface morphology,porosity,and hyd...Ti-Mo getters have been fabricated via metal injection molding (MIM) using three kinds of Ti powders with different mean particle sizes of 46 μm,35 μm and 26 μm,respectively. The surface morphology,porosity,and hydrogen sorption properties of Ti-Mo getters formed by MIM using paraffin wax as a principal binder constituent were examined. It has been proven that the powder injection molding is a viable forming technique for porous Ti-Mo getters. The particle size of Ti powders and the powder loading influence...展开更多
The demand for getters with high sorption efficiency has generated a need for resources to assist in qualification of getter materials for their practical use. This paper discusses innovative steps which should provid...The demand for getters with high sorption efficiency has generated a need for resources to assist in qualification of getter materials for their practical use. This paper discusses innovative steps which should provide a dramatic improvement in the selection and application of getter technologies used in various processes. The first step was to build a natural classification of chemisorbents, from which we obtain a corresponding order of suitability related to known getter products. The classification system suggested by the authors is based on criteria which are directly connected with the sorption behavior of the material. This has lead to the challenge of developing of a computing algorithm for characterization of sorption properties of getter materials and for solving the inverse problem—the problem of designing a chemisorbent based on the requirements of a fully realized application. The employment of the new methodology is demonstrated in the example of the calculations supporting the selection of getter films for MEMS.展开更多
The efficiency of sorption purification of gases, as measured by an improvement in product quality and/or lowering of its cost, can be significantly increased via simple solutions: the substitution of current getter t...The efficiency of sorption purification of gases, as measured by an improvement in product quality and/or lowering of its cost, can be significantly increased via simple solutions: the substitution of current getter technology with reactive getters;and stimulation of the material in the sorption process using mechanochemical methods instead of heating or cooling. These ideas were embodied by the authors in new sorption apparatuses and devices such as mechanochemical sorption apparatuses for production of ultra pure gases, improved gas purifiers with reactive sorbent for production of pure and high purity gases and, finally, fluidized bed columns for mass production of pure and high purity gases.展开更多
The results of observation of different structuring techniques of thin metal layers applied in micro system technologies are presented. The Ti V getter films formed by magnetron sputtering have been explored using sca...The results of observation of different structuring techniques of thin metal layers applied in micro system technologies are presented. The Ti V getter films formed by magnetron sputtering have been explored using scanning electron and atomic-force microscopy, Brunauer-Emmett-Teller method, thermogravimetric analysis and fractal geometry. The film sorption capacity for hydrogen given by thermogravimetry was of 7.7 m3·Pa·g-1. To estimate the effective surface area, the fractal geometry tools were used and the calculated value of the specific surface area was about 155 m2/m3. The second object under investigation was a structure composed of micro- and mesoporous silicon and copper layer deposited electrochemically on the pore walls. Porous silicon when coupled with a reactive metal or alloy is expected to be an effective getter for micro system techniques. The use of porous silicon and specific conditions of depositions allows to form the structure of complex fractal type with a specific surface area of 167 m2/cm3.展开更多
A dynamic phosphor-silicate glass （PSG） gettering method is proposed in which the processes of the gettering of Ni by PSC and the crystallizing of α-Si into poly-Si by Ni take place simultaneously. The effects of P...A dynamic phosphor-silicate glass （PSG） gettering method is proposed in which the processes of the gettering of Ni by PSC and the crystallizing of α-Si into poly-Si by Ni take place simultaneously. The effects of PSC gettering process on the performances of solution-based metal induced crystallized （S-MIC） poly-Si materials and their thin film transistors （TFTs） are discussed. The crystallization rate is much reduced due to the fact that the Ni as a medium source of crystallization is extracted by the PSC during crystallization at the same time. The boundary between two neighbouring grains in S-MIC poly-Si with PSG looks blurrier than without PSG. Compared with the TFTs made from S-MIC poly-Si without PSC gettering, the TFTs made with PSC gettering has a reduced gate induced leakage current.展开更多
Hazy backside gettering of boron-doped <111> siljcon wafer with a-Si: H film deposited by rf glow discharge technique (rf-GD) has been investigated by SEM, optical microscope and preferential etching tech- lique...Hazy backside gettering of boron-doped <111> siljcon wafer with a-Si: H film deposited by rf glow discharge technique (rf-GD) has been investigated by SEM, optical microscope and preferential etching tech- lique. lt is evident that the deposited film can effectively getter the haze after annealing at l l00℃in wet oxy- len ambient for 120 min. The pre-crystallization annealing at 650℃ in argon ambient for 10 min enhances the gettering effectiveness. The low temperature(200～300℃) process of growing extrinsic gettering film reduces the processing contamination.展开更多
ZrCoCe getter films with thickness of ~2.3 lm were deposited on Si(100) wafers by direct current(DC)magnetron sputtering process. A 400-nm-thick Pd protection layer was then deposited on the as-deposited ZrCoCe film w...ZrCoCe getter films with thickness of ~2.3 lm were deposited on Si(100) wafers by direct current(DC)magnetron sputtering process. A 400-nm-thick Pd protection layer was then deposited on the as-deposited ZrCoCe film without exposure to atmosphere. Microstructure, surface morphology and surface chemical state of the films were analyzed. Moreover, hydrogen sorption properties were determined. The results show that the ZrCoCe film displays a cauliflower-like morphology and a porous columnar-like structure which is composed of nanocrystal grains. The Pd protection layer tightly adheres to the surface of the ZrCoCe film and efficiently prevents the oxidation of Zr under exposure to atmosphere. We find that the hydrogen sorption properties of the Pd-ZrCoCe film are significantly improved,in comparison with those of the as-deposited ZrCoCe film.展开更多
The present work continues a series of publications devoted to the study of the sorption properties of reactive alloys based on IIA metals and the development of advanced getter materials for gas and vacuum technologi...The present work continues a series of publications devoted to the study of the sorption properties of reactive alloys based on IIA metals and the development of advanced getter materials for gas and vacuum technologies. This publication attempts to answer the current challenges in the field of gas sorption associated with the emergence of new vacuum products such as vacuum insulated glasses, electronic systems, cryogenic devices, etc. An analysis of the problems that arise here, as well as the results of sorption measurements, carried out with the participation of intermetallic phases of the composition CaLi<sub>2</sub> and Ca<sub>0.33</sub>Li<sub>0.48</sub>Mg<sub>0.19</sub>, show that the best getter support for these new hermetically sealed products can be provided by intermetallic compounds formed in systems Li-IIA metals. Intermetallic phases of this family are easy to manufacture and demonstrate outstanding service characteristics: their specific sorption capacity is recorded high, exceeding traditional gas sorbents in this respect by at least an order of magnitude;the kinetics of gas capturing is set at the stage of alloy production, i.e., is adjustable;the temporary resistance of these phases to atmospheric gases allows to install the getter at its workplace in air, without further thermal activation. The sorption superiority of reactive intermetallics is explained by their special sorption mechanism: the gas/metal interaction is formed here as a combination of two processes, continuous growth of reaction products on a metallic surface and corrosion decay of brittle intermetallic phase under mechanical forces, which feeds the chemical reaction with a fresh surface. The advantages of sorption processes of this new type are undoubted and significant: compared with the conventional sorbents, an intermetallic getter reactant solves two important problems;it reduces production costs and increases the sorption yield.展开更多
A new method for chemical pumping of gases has been developed using reactive alloys of Li with IIA metals in the liquid state. It is an answer to the need for ultra-high and extremely high vacuum without loose solid p...A new method for chemical pumping of gases has been developed using reactive alloys of Li with IIA metals in the liquid state. It is an answer to the need for ultra-high and extremely high vacuum without loose solid particles. Another application of this development is the production of high- and ultra-pure noble gases in a one-step process. Both of these solutions are unprecedented;they are based on a new gas/melt sorption interface that raises the overall bar of technical advances in the field to a higher level, simplifying sorption equipment and leading to cost savings.展开更多
Al precipitates as well as cavities (or open-volume detects) are known for their ability to getter impuri-ties within Si. In order to compare their relative gettering strength we produced both Al precipitates and cavi...Al precipitates as well as cavities (or open-volume detects) are known for their ability to getter impuri-ties within Si. In order to compare their relative gettering strength we produced both Al precipitates and cavities atdifferent depths within one Si wafer. This was done by H+ and Al+ implantation with different energies and subse-quent annealing process, resulting in Al-Si alloy and cavities at depth of 300 nm and 800 nm, respectively. Cu wasthen implanted with an energy of 70 keV to a fluence of 1 × 1014 / cm2. The Cu implanted samples were annealed attemperature from 700℃ to 1200℃. It was found that Cu impurities were gettered primarily by the precipitated Allayer rather than by cavities at the temperature of 700～1000℃, while gettering of Cu occured in both regions at thetemperature of 1200℃. The secondary ion mass spectrometry and transmission electron microscopy analyses wereused to reveal the interaction between Cu impurities and defects at different trap sites.展开更多
Oxygen gettering in Si by the He induced cavity layer was investigated in this work.A cavity layer was generated in Si sample by He implantation and annealing.The morphology of the cavity layer depending on the dose o...Oxygen gettering in Si by the He induced cavity layer was investigated in this work.A cavity layer was generated in Si sample by He implantation and annealing.The morphology of the cavity layer depending on the dose of He and the annealing temperature was presented in the paper.This cavity layer may serve as an efficient oxygen gettering layer during the high temperature oxidation process and accumulate the oxygen from the annealing atmosphere as well as the implanted oxygen.The phenomenon gives the idea that the cavity layer can be employed to define the oxide formation in Si and further to facilitate the formation of the buried oxide layer(BOX) in Si aiming at the Si-on-Insulator(SOI) structure fabrication.The oxygen gettering ability of the cavity layer in Si was investigated by cross section transmission electron microscopy and auger electron spectroscopy.展开更多
A rapid thermal process (RTP) was first introduced into the intrinsic gettering (IG) processes of fast neutron irradiated Czochralski (CZ) silicon. The effect of RTP conditions on bulk microdefects (BMDs) and denuded ...A rapid thermal process (RTP) was first introduced into the intrinsic gettering (IG) processes of fast neutron irradiated Czochralski (CZ) silicon. The effect of RTP conditions on bulk microdefects (BMDs) and denuded zone (DZ) was investigated. Fourier transform infrared absorption spectrometer (FTIR) was used to measure the concentration of interstitial oxygen ([Oi]). Bulk microdefects were observed by optical microscope. The results show that, according to the variation of [Oi], it is found that RTP doesn’t change the processes of oxygen precipitation in fast neutron irradiated Czochralski silicon. Perfect denuded zone, dense oxygen precipitates and defects form in the bulk of irradiated samples. With increasing temperature of RTP, the width of denuded zone decreases. Increasing RTP cooling rate, the density of Bulk microdefects increases. DZ forms in the sample that annealed in nitrogen atmosphere.展开更多
The biggest barrier for photovoltaic (PV) utilization is its high cost, so the key for scale PV utiliza-tion is to further decrease the cost of solar cells. One way to improve the efficiency, and therefore lower the c...The biggest barrier for photovoltaic (PV) utilization is its high cost, so the key for scale PV utiliza-tion is to further decrease the cost of solar cells. One way to improve the efficiency, and therefore lower the cost, is to increase the minority carrier lifetime by controlling the material defects. The main defects in grain boundaries of polycrystalline silicon gettered by porous silicon and heavy phosphorous diffusion have been studied. The porous silicon was formed on the two surfaces of wafers by chemical etching. Phosphorous was then diffused into the wafers at high temperature (900℃). After the porous silicon and diffusion layers were removed, the minority carrier lifetime was measured by photo-conductor decay. The results show that the lifetime抯 minority carriers are increased greatly after such treatment.展开更多
Introduction The pumping performance of getter materials has becoming one of the hotspots in accelerator field.The recovery of pumping performance after air venting,also called aging effect,is important for applicatio...Introduction The pumping performance of getter materials has becoming one of the hotspots in accelerator field.The recovery of pumping performance after air venting,also called aging effect,is important for applications in accelerators.Materials and methods In this work,we investigated the aging effect of Ti-V-Zr-Hf-and Ti-V-Zr-coated copper tubular chambers,and the effect of initial air exposure time on the aging properties.The samples presented hierarchically micro/nano-structures and showed a featured aging curve,giving about 9 effective pumping cycles.Conclusion The pumping performance is inversely correlated with air exposure time suggesting that the getter coated cham-bers should be properly preserved before applied as a"pump".展开更多
In this paper, the gettering of Cu impurities in silicon-on-insulator (SOI)materials is studied. Nanovoids are formed in the substrate of SOI beneath the buried oxide (BOX) byroom temperature H^+ (3.5 x 10^(16) / cm^2...In this paper, the gettering of Cu impurities in silicon-on-insulator (SOI)materials is studied. Nanovoids are formed in the substrate of SOI beneath the buried oxide (BOX) byroom temperature H^+ (3.5 x 10^(16) / cm^2) or He^+ (9 x 10^(16) / cm^2) implantation andsubsequent annealing at 700℃. The gettering of different doses of Cu (5 x10^(13)/cm^2, 5x10^(14)/cm^2, 5 x 10^(15)/cm^2), which are introduced in the top Si layer by ion implantation, to thenanovoids are investigated by cross-section transmission electron microscopy (XTEM) and secondaryion mass spectroscopy (SIMS). The results demonstrate that Cu impurities in the top Si layer candiffuse through the buried oxide (BOX) layer of SIMOX and Smart-Cut SOI at temperature above 700℃and be trapped by the nanovoids. Some of Cu impurities can be captured by the intrinsic defects atthe BOX interface of SIMOX, but will be released out at high temperatures. The gettering effect ofSIMOX intrinsic defects at BOX is much rower than that of the nanovoids. No Cu impurities aretrapped at the perfect BOX interfaces of Smart-Cut SOI. After 1000℃ annealing, high dose of Cu (3.6x 10^(15)/cm^2) was gettered by the nanovoids. The Cu gettering efficiency to the nanovoidsincreased with the decreasing of Cu doses. When the Cu doses in the top Si layer were lower than 4 x10^(15) /cm^2, nanovoids could getter more than 90% of the Cu impurities and reduce the Cuconcentration in the top Si layer to less than 4%. The results indicate that nanovoids gettering isa promising method for removing the impurities in SOI materials.展开更多
文摘The effect of rapid thermal annealing （RTA） ambient on denuded zone and oxygen precipitates in Czochralski （CZ） silicon wafers is studied in this paper. N2 and a N2/NH3 mixture are used as RTA ambient. It is demonstrated that a high density of oxygen precipitates and thin denuded zone are obtained in N2/NH3 ambient,while a relatively lower density of oxygen precipitates and thicker denuded zone are observed in N2 ambient. As the RTA duration times increased, the oxygen precipitate density increased and the denuded zone depth decreased. X-ray photoelectron spectroscopy （XPS） data and atomic force microscope （AFM） results show that there RTA process,which can explain the different effect of RTA was a surface nitriding reaction during the N2/NH3 ambient ambient.
基金Projects (60906002, 50832006) supported by the National Natural Science Foundation of ChinaProject (2009QNA4007) supported by the Fundamental Research Funds for the Central Universities, China
文摘The precipitation and gettering behaviors of copper （Cu） at different defective regions in multicrystalline silicon were investigated by combining scanning infrared microscopy, optical microscopy, inductively coupled plasma mass spectrometry and microwave photo-conductance decay. It is found that the behaviors of Cu precipitation are strongly dependent on the defect density. Most of the Cu contaminants tend to form precipitates homogeneously in the low density defect region, while they mostly segregate at the defects and form precipitates heterogeneously in the high density defect region. In the case of heavy contamination, the Cu precipitate can significantly reduce the carrier lifetime of multicrystalline silicon due to their Schottkydiode behavior in the silicon substrate. A 900 °C rap thermal process （RTP） phosphorus gettering anneal cannot be sufficiently effective to remove the Cu precipitates in these two regions.
文摘The effects of Mo on the microstructure evolution, porosity and hydrogen sorption properties of Ti-Mo getters are investigated in this work. The results show that the addition of Mo prolongs the densification process of Ti-Mo getters and results in a significant amount of sintered pores. With the Mo content increasing, the porosity of getters firstly increases reaching the maximum value as it attains about 7.5wt.%, and then drops. At the room temperature, the hydrogen sorption property of getters increases progressively with the Mo content increasing, but the tendency is not very clear before its content lies below 2.5wt.%. When the Mo content achieves about 7.5wt.%, the hydrogen sorption property proves to be the best. The discussion is made about the above mentioned phenomena inclusive of hydrogen sorption properties of getters under different activation conditions （from 500-750℃）.
基金supported by the National Natural Science Foundation of China(Grant No.11604246)the China Postdoctoral Science Foundation(Grant No.2016M592714)+2 种基金the Professional Practice Demonstration Base for Professional Degree Graduate in Material Engineering of Henan Polytechnic University,China(Grant No.2016YJD03)the Funds from the Education Department of Henan Province,China(Grant Nos.12A430010 and 17A430020)the Project for Key Science and Technology Research of Henan Province,China(Grant No.162102210275)
文摘In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature（HPHT） by using the temperature gradient method（TGM）, with adopting Ti/Cu as the nitrogen getter in Ni70Mn25Co5（abbreviated as NiMnCo） or Fe（55）Ni（29）Co（16）（abbreviated FeNiCo） catalyst. The values of nitrogen concentration（Nc） in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo or Ti/Cu（1.8 wt%） is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-Ⅱa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu（1.6 wt%） is added in the FeNiCo catalyst.
文摘Ti-Mo getters have been fabricated via metal injection molding (MIM) using three kinds of Ti powders with different mean particle sizes of 46 μm,35 μm and 26 μm,respectively. The surface morphology,porosity,and hydrogen sorption properties of Ti-Mo getters formed by MIM using paraffin wax as a principal binder constituent were examined. It has been proven that the powder injection molding is a viable forming technique for porous Ti-Mo getters. The particle size of Ti powders and the powder loading influence...
文摘The demand for getters with high sorption efficiency has generated a need for resources to assist in qualification of getter materials for their practical use. This paper discusses innovative steps which should provide a dramatic improvement in the selection and application of getter technologies used in various processes. The first step was to build a natural classification of chemisorbents, from which we obtain a corresponding order of suitability related to known getter products. The classification system suggested by the authors is based on criteria which are directly connected with the sorption behavior of the material. This has lead to the challenge of developing of a computing algorithm for characterization of sorption properties of getter materials and for solving the inverse problem—the problem of designing a chemisorbent based on the requirements of a fully realized application. The employment of the new methodology is demonstrated in the example of the calculations supporting the selection of getter films for MEMS.
文摘The efficiency of sorption purification of gases, as measured by an improvement in product quality and/or lowering of its cost, can be significantly increased via simple solutions: the substitution of current getter technology with reactive getters;and stimulation of the material in the sorption process using mechanochemical methods instead of heating or cooling. These ideas were embodied by the authors in new sorption apparatuses and devices such as mechanochemical sorption apparatuses for production of ultra pure gases, improved gas purifiers with reactive sorbent for production of pure and high purity gases and, finally, fluidized bed columns for mass production of pure and high purity gases.
文摘The results of observation of different structuring techniques of thin metal layers applied in micro system technologies are presented. The Ti V getter films formed by magnetron sputtering have been explored using scanning electron and atomic-force microscopy, Brunauer-Emmett-Teller method, thermogravimetric analysis and fractal geometry. The film sorption capacity for hydrogen given by thermogravimetry was of 7.7 m3·Pa·g-1. To estimate the effective surface area, the fractal geometry tools were used and the calculated value of the specific surface area was about 155 m2/m3. The second object under investigation was a structure composed of micro- and mesoporous silicon and copper layer deposited electrochemically on the pore walls. Porous silicon when coupled with a reactive metal or alloy is expected to be an effective getter for micro system techniques. The use of porous silicon and specific conditions of depositions allows to form the structure of complex fractal type with a specific surface area of 167 m2/cm3.
基金Project supported by the National High Technology Research and Developments Program of China (Grant No 004AA33570)Key Project of National Natural Science Foundation of China (NSFC) (Grant No 60437030)Tianjin Natural Science Foundation(Grant No 05YFJMJC01400)
文摘A dynamic phosphor-silicate glass （PSG） gettering method is proposed in which the processes of the gettering of Ni by PSC and the crystallizing of α-Si into poly-Si by Ni take place simultaneously. The effects of PSC gettering process on the performances of solution-based metal induced crystallized （S-MIC） poly-Si materials and their thin film transistors （TFTs） are discussed. The crystallization rate is much reduced due to the fact that the Ni as a medium source of crystallization is extracted by the PSC during crystallization at the same time. The boundary between two neighbouring grains in S-MIC poly-Si with PSG looks blurrier than without PSG. Compared with the TFTs made from S-MIC poly-Si without PSC gettering, the TFTs made with PSC gettering has a reduced gate induced leakage current.
文摘Hazy backside gettering of boron-doped <111> siljcon wafer with a-Si: H film deposited by rf glow discharge technique (rf-GD) has been investigated by SEM, optical microscope and preferential etching tech- lique. lt is evident that the deposited film can effectively getter the haze after annealing at l l00℃in wet oxy- len ambient for 120 min. The pre-crystallization annealing at 650℃ in argon ambient for 10 min enhances the gettering effectiveness. The low temperature(200～300℃) process of growing extrinsic gettering film reduces the processing contamination.
基金financially supported by the National Natural Science Foundation of China(No.61874137)。
文摘ZrCoCe getter films with thickness of ~2.3 lm were deposited on Si(100) wafers by direct current(DC)magnetron sputtering process. A 400-nm-thick Pd protection layer was then deposited on the as-deposited ZrCoCe film without exposure to atmosphere. Microstructure, surface morphology and surface chemical state of the films were analyzed. Moreover, hydrogen sorption properties were determined. The results show that the ZrCoCe film displays a cauliflower-like morphology and a porous columnar-like structure which is composed of nanocrystal grains. The Pd protection layer tightly adheres to the surface of the ZrCoCe film and efficiently prevents the oxidation of Zr under exposure to atmosphere. We find that the hydrogen sorption properties of the Pd-ZrCoCe film are significantly improved,in comparison with those of the as-deposited ZrCoCe film.
文摘The present work continues a series of publications devoted to the study of the sorption properties of reactive alloys based on IIA metals and the development of advanced getter materials for gas and vacuum technologies. This publication attempts to answer the current challenges in the field of gas sorption associated with the emergence of new vacuum products such as vacuum insulated glasses, electronic systems, cryogenic devices, etc. An analysis of the problems that arise here, as well as the results of sorption measurements, carried out with the participation of intermetallic phases of the composition CaLi<sub>2</sub> and Ca<sub>0.33</sub>Li<sub>0.48</sub>Mg<sub>0.19</sub>, show that the best getter support for these new hermetically sealed products can be provided by intermetallic compounds formed in systems Li-IIA metals. Intermetallic phases of this family are easy to manufacture and demonstrate outstanding service characteristics: their specific sorption capacity is recorded high, exceeding traditional gas sorbents in this respect by at least an order of magnitude;the kinetics of gas capturing is set at the stage of alloy production, i.e., is adjustable;the temporary resistance of these phases to atmospheric gases allows to install the getter at its workplace in air, without further thermal activation. The sorption superiority of reactive intermetallics is explained by their special sorption mechanism: the gas/metal interaction is formed here as a combination of two processes, continuous growth of reaction products on a metallic surface and corrosion decay of brittle intermetallic phase under mechanical forces, which feeds the chemical reaction with a fresh surface. The advantages of sorption processes of this new type are undoubted and significant: compared with the conventional sorbents, an intermetallic getter reactant solves two important problems;it reduces production costs and increases the sorption yield.
文摘A new method for chemical pumping of gases has been developed using reactive alloys of Li with IIA metals in the liquid state. It is an answer to the need for ultra-high and extremely high vacuum without loose solid particles. Another application of this development is the production of high- and ultra-pure noble gases in a one-step process. Both of these solutions are unprecedented;they are based on a new gas/melt sorption interface that raises the overall bar of technical advances in the field to a higher level, simplifying sorption equipment and leading to cost savings.
基金Supported by the National Natural Science Foundation of China(No.69906005)and the Shanghai Youth Foundation(No.01QMH1403)
文摘Al precipitates as well as cavities (or open-volume detects) are known for their ability to getter impuri-ties within Si. In order to compare their relative gettering strength we produced both Al precipitates and cavities atdifferent depths within one Si wafer. This was done by H+ and Al+ implantation with different energies and subse-quent annealing process, resulting in Al-Si alloy and cavities at depth of 300 nm and 800 nm, respectively. Cu wasthen implanted with an energy of 70 keV to a fluence of 1 × 1014 / cm2. The Cu implanted samples were annealed attemperature from 700℃ to 1200℃. It was found that Cu impurities were gettered primarily by the precipitated Allayer rather than by cavities at the temperature of 700～1000℃, while gettering of Cu occured in both regions at thetemperature of 1200℃. The secondary ion mass spectrometry and transmission electron microscopy analyses wereused to reveal the interaction between Cu impurities and defects at different trap sites.
文摘Oxygen gettering in Si by the He induced cavity layer was investigated in this work.A cavity layer was generated in Si sample by He implantation and annealing.The morphology of the cavity layer depending on the dose of He and the annealing temperature was presented in the paper.This cavity layer may serve as an efficient oxygen gettering layer during the high temperature oxidation process and accumulate the oxygen from the annealing atmosphere as well as the implanted oxygen.The phenomenon gives the idea that the cavity layer can be employed to define the oxide formation in Si and further to facilitate the formation of the buried oxide layer(BOX) in Si aiming at the Si-on-Insulator(SOI) structure fabrication.The oxygen gettering ability of the cavity layer in Si was investigated by cross section transmission electron microscopy and auger electron spectroscopy.
基金Project (50472034) supported by the National Natural Science Foundation of China Project(E2005000048) supported by the Natural Science Foundation of Hebei Province, China Project(20050080006) supported by the Specialized Research Fund for the Doctoral Program of Higher Education, China
文摘A rapid thermal process (RTP) was first introduced into the intrinsic gettering (IG) processes of fast neutron irradiated Czochralski (CZ) silicon. The effect of RTP conditions on bulk microdefects (BMDs) and denuded zone (DZ) was investigated. Fourier transform infrared absorption spectrometer (FTIR) was used to measure the concentration of interstitial oxygen ([Oi]). Bulk microdefects were observed by optical microscope. The results show that, according to the variation of [Oi], it is found that RTP doesn’t change the processes of oxygen precipitation in fast neutron irradiated Czochralski silicon. Perfect denuded zone, dense oxygen precipitates and defects form in the bulk of irradiated samples. With increasing temperature of RTP, the width of denuded zone decreases. Increasing RTP cooling rate, the density of Bulk microdefects increases. DZ forms in the sample that annealed in nitrogen atmosphere.
文摘The biggest barrier for photovoltaic (PV) utilization is its high cost, so the key for scale PV utiliza-tion is to further decrease the cost of solar cells. One way to improve the efficiency, and therefore lower the cost, is to increase the minority carrier lifetime by controlling the material defects. The main defects in grain boundaries of polycrystalline silicon gettered by porous silicon and heavy phosphorous diffusion have been studied. The porous silicon was formed on the two surfaces of wafers by chemical etching. Phosphorous was then diffused into the wafers at high temperature (900℃). After the porous silicon and diffusion layers were removed, the minority carrier lifetime was measured by photo-conductor decay. The results show that the lifetime抯 minority carriers are increased greatly after such treatment.
基金supported by High Energy Photon Source(HEPS),a major national science and technology infrastructureprovided by National Development and Reform Commission(Grant No.发改高技(2017)2173号)
文摘Introduction The pumping performance of getter materials has becoming one of the hotspots in accelerator field.The recovery of pumping performance after air venting,also called aging effect,is important for applications in accelerators.Materials and methods In this work,we investigated the aging effect of Ti-V-Zr-Hf-and Ti-V-Zr-coated copper tubular chambers,and the effect of initial air exposure time on the aging properties.The samples presented hierarchically micro/nano-structures and showed a featured aging curve,giving about 9 effective pumping cycles.Conclusion The pumping performance is inversely correlated with air exposure time suggesting that the getter coated cham-bers should be properly preserved before applied as a"pump".
基金supported by the National Natural Science Foundation of China (Grant No. 69906005) and Shanghai Youth Foundation under grant No. 01QMH1403. The authors would like to thank Prof. P. F. P. Fichtner at Universidade do Rio Grande do Sul Brazil for the TEM an
文摘In this paper, the gettering of Cu impurities in silicon-on-insulator (SOI)materials is studied. Nanovoids are formed in the substrate of SOI beneath the buried oxide (BOX) byroom temperature H^+ (3.5 x 10^(16) / cm^2) or He^+ (9 x 10^(16) / cm^2) implantation andsubsequent annealing at 700℃. The gettering of different doses of Cu (5 x10^(13)/cm^2, 5x10^(14)/cm^2, 5 x 10^(15)/cm^2), which are introduced in the top Si layer by ion implantation, to thenanovoids are investigated by cross-section transmission electron microscopy (XTEM) and secondaryion mass spectroscopy (SIMS). The results demonstrate that Cu impurities in the top Si layer candiffuse through the buried oxide (BOX) layer of SIMOX and Smart-Cut SOI at temperature above 700℃and be trapped by the nanovoids. Some of Cu impurities can be captured by the intrinsic defects atthe BOX interface of SIMOX, but will be released out at high temperatures. The gettering effect ofSIMOX intrinsic defects at BOX is much rower than that of the nanovoids. No Cu impurities aretrapped at the perfect BOX interfaces of Smart-Cut SOI. After 1000℃ annealing, high dose of Cu (3.6x 10^(15)/cm^2) was gettered by the nanovoids. The Cu gettering efficiency to the nanovoidsincreased with the decreasing of Cu doses. When the Cu doses in the top Si layer were lower than 4 x10^(15) /cm^2, nanovoids could getter more than 90% of the Cu impurities and reduce the Cuconcentration in the top Si layer to less than 4%. The results indicate that nanovoids gettering isa promising method for removing the impurities in SOI materials.
