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Thin film SQUIDs for magnetic field measurements
World Abstracts continued from page 39
is to discuss manufacturing-related problems encountered when lifetime, one in particular has been found to have minimum effect on screen printing of conductive epoxies for use in die attachment, and to normal chip, substrate, and module processing: the use of a leadevaluate and reoommend a screenable epoxy system for use in high- indium solder system. Terminals of 50lnPb - that is, 50% indium by rate production applications. The study described herein has been weight, the rest lead - give a 3:1 improvement in lifetime over categorised according to: (1) materials characterisation; and (2) screen corresponding 5SnPb joints, and are generally compatible with printing. The materials characterisation study which consisted of present chip and substrate manufacturing processes. Alloys containing determining physical, mechanical, electrical, and thermal properties more than 50% indium produce even greater reliability, but may make was conducted on five silver-filled adhesives. Based on the results of it necessary to modify some processes. InPb reacts faster than SnPb in the characterisation study, three adhesives were selected for screen a high-humidity environment, especially in the presence of chlorine. printing evaluation. Screen printing evaluation of the three adhesives This must be considered a potential risk for any use of InPb. selected was categorised according to: (1) screen printing variables and processes; and (2) mechanical and environmental testing per MIL-Std 883. The three adhesive systems evaluated were all found acceptable Thin film SQUIDs for magnetic field measurements for screen printing applications. However, variables such as screen G. EHNHOLM, T. WIIK and T. STUBB mesh, gold substrate cleanliness, device placement method, and time Proceedings of the 8th Conference (1976 International) on Solid elapsed between screening and curing were all found to have a State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, significant effect on bond reliability. Supplement 16-1, pp.261-263 (1977). Construction and properties of a thin film SQUID is described. The S Q U I D is based on resistively shunted niobium-niobium oxide-lead New gold alloy for aluminium bonding in MOS hermetic packages tunnel junctions deposited on a fiat substrate. The origin and conR. L. D I E T Z sequences of flux trapping in these SQUIDs is presented. Proc. Electron. Components Conf., Arlington, Va., p.367 (May 1977). A comparison is made in the performance of a standard gold, a typical silver alloy, and a new gold alloy when used in MOS hermetic package Investigations of metal contacts to amorphous evaporated Ge films applications. "the bond strength and resistances of aluminium wire M. HAFIZ, E. MGBENU, P. A. TOVE, H. NORDE and bonds were shown to be comparable for the silver alloy and the new S. PETERSSON gold alloy when subjected to a typical sealing profile. The atuminium Vacuum, 27(3), p.193 (1977). wire bonds made to the standard frited gold degraded to an unAmorphous Ge films are used as non-injecting ohmic contacts to acceptable level. Metallurgical analysis of aluminium wire bonds showed the 'purple plague' intermetallic of gold and aluminium did not high-resistivity n-silicon radiation detectors, but the function of this contribute to the loss of bond strength or the increase in bond contact is not yet fully explored. One part problem is the rrle of the resistance normally encountered during the seal cycle. Also shown was metal films used as external contacts to the amorphous film. In this the aluminium diffusion rate to be significantly retarded in the gold paper we investigate the function of different contacting metals, such alloy as compared to the standard gold. A failure mechanism was as Au, AI, Cr by measuring the I-V characteri.stics of sandwich structures with two metals on both sides of the amorphous evaporated proposed. Ge film (of typical thickness l#m). Cadmium telluride nuclear radiation detectors P. HOSCHL, P. POL[VKA, V. PROSSER, M. SKRIVANKOVA and M. V I D R A Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.279-281 (1977). c a d m i u m telluride, has an excellent gamma-ray stopping power compared with traditional detector materials like Ge and Si. The growth of CdTe from Te solvent was used to obtain material for nuclear radiation detectors. The quality of detectors was tested by 5rCo and 2*~Am. Total resolution is approximately 7keV (FWHM) for 122keV gamma STCo and 5keV (FWHM) for 59keV gamma 24~Am.
Anodic oxidation and MOS devices of GaAs and GaP T. IKOMA, H. T O K U D A , H. YOKOMIZO and Y. ADACHI Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.475-479 (1977). Chemical and electric properties of the anodic oxide films of GaAs and G a P are investigated under various annealing conditions. Analysis of the oxidation current proves that the oxide grows at constant field condition on p-GaAs and at constant resistivity condition on n-GaAs under the pseudo constnt voltage biasing. Proper annealing improves C-V curves of a p-GaAs MOS diode to almost the ideal case, while the improvement is small for an n-GaAs diode. It is found that the change of the C-V and G-V curves is influenced by annealing temperatures rather than by annealing gases. Effects of the bias-temperature (BT) treatment are also shown. Lead-indium for controlled-collapse chip joining L. S. GOLDMANN, R. J. H E R D Z I K , N. G. KOOPMAN and V. C. M A R C O T r E Proc. Electron. Components Conf., Arlington, Va., p.25 (May 1977). A major requirement of controlled-coUap~e flip-chip, solder interconnections, shared by most other electronic interconnections, is the ability to absorb strains arising from the thermal mismatch of unlike materials within the package. In particular, mismatch between the alumina substrate and the silicon chip produces a shearing motion on each joint each time the machine is turned on or off, and to a secondary extent each time the ship is powered or addressed. An inability to withstfind mismatch strains leads to mechanical fracture and premature end of life. Among the many methods for increasing 40
High purity chemicals in semicon production K. G. CLARK, E. M. J U L E F F a n d S. FAWCE'Vr Electron. Prod., p.43 (April 1977). In the field of wet processing chemicals 'electronic' or 'semiconductor" grade materials have been available for a number of years and have been widely used in the mieroelectronics industry especially by the manufacturers of MOS and surface effect integrated circuits. These chemicals have been manufactured worldwide by leading chemical companies in bulk quantities and in this bulk state have been able to meet their published specifications however, in the methods employed for bottling and in the bottles themselves inorganic solids and metallic materials have been added to the liquid chemicals often in significant quantities of impurities and being measured at many hundred to tens of thousands of particles at a whole range of sizes from sub-micron to 50p.m or greater particle size and at impurity levels of 1.00 to 1.00ppm of a given inorganic impurity. Some of these chemicals also contain the origin salts at a relatively high impurity level, for intance, ammonium fluoride solution (the largest volume component in SiOz etchants) normally contains several ppm of solid calcium salt in its originating raw material calcium fluoride. A study has been made of both the particulate matter found in bottled 'electronic/semiconductor' grade chemicals and the impurity levels found both of which deviate in all cases from the manufacturers specification for the chemical solution. Influence of temperature on the structure and properties of an anodised native GaAs oxide T. ISHII and B. JEPPSSON Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.471-474 (1977). The influence of temperature on the properties, the composition and the structure of the anodically grown native GaAs oxide is investigated. The oxide is very stable below 35ff'C. Above 350°C, the oxide begins to decompose first by releasing water. The oxide decomposes most rapidly around 450°C mainly by vaporising water and arsenic monoxide. By decomposition, drastic changes of oxide properties and composition are observed. The oxide decomposition is completed at 700°C resulting in pure gallium oxide. By coating SiO2 film on top of the anodised oxide film, GaAs is possible to be heat-treated at 800°C for 2 hours without any degradation of the GaAs surface.
is to discuss manufacturing-related problems encountered when lifetime, one in particular has been found to have minimum effect on screen printing of conductive epoxies for use in die attachment, and to normal chip, substrate, and module processing: the use of a leadevaluate and reoommend a screenable epoxy system for use in high- indium solder system. Terminals of 50lnPb - that is, 50% indium by rate production applications. The study described herein has been weight, the rest lead - give a 3:1 improvement in lifetime over categorised according to: (1) materials characterisation; and (2) screen corresponding 5SnPb joints, and are generally compatible with printing. The materials characterisation study which consisted of present chip and substrate manufacturing processes. Alloys containing determining physical, mechanical, electrical, and thermal properties more than 50% indium produce even greater reliability, but may make was conducted on five silver-filled adhesives. Based on the results of it necessary to modify some processes. InPb reacts faster than SnPb in the characterisation study, three adhesives were selected for screen a high-humidity environment, especially in the presence of chlorine. printing evaluation. Screen printing evaluation of the three adhesives This must be considered a potential risk for any use of InPb. selected was categorised according to: (1) screen printing variables and processes; and (2) mechanical and environmental testing per MIL-Std 883. The three adhesive systems evaluated were all found acceptable Thin film SQUIDs for magnetic field measurements for screen printing applications. However, variables such as screen G. EHNHOLM, T. WIIK and T. STUBB mesh, gold substrate cleanliness, device placement method, and time Proceedings of the 8th Conference (1976 International) on Solid elapsed between screening and curing were all found to have a State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, significant effect on bond reliability. Supplement 16-1, pp.261-263 (1977). Construction and properties of a thin film SQUID is described. The S Q U I D is based on resistively shunted niobium-niobium oxide-lead New gold alloy for aluminium bonding in MOS hermetic packages tunnel junctions deposited on a fiat substrate. The origin and conR. L. D I E T Z sequences of flux trapping in these SQUIDs is presented. Proc. Electron. Components Conf., Arlington, Va., p.367 (May 1977). A comparison is made in the performance of a standard gold, a typical silver alloy, and a new gold alloy when used in MOS hermetic package Investigations of metal contacts to amorphous evaporated Ge films applications. "the bond strength and resistances of aluminium wire M. HAFIZ, E. MGBENU, P. A. TOVE, H. NORDE and bonds were shown to be comparable for the silver alloy and the new S. PETERSSON gold alloy when subjected to a typical sealing profile. The atuminium Vacuum, 27(3), p.193 (1977). wire bonds made to the standard frited gold degraded to an unAmorphous Ge films are used as non-injecting ohmic contacts to acceptable level. Metallurgical analysis of aluminium wire bonds showed the 'purple plague' intermetallic of gold and aluminium did not high-resistivity n-silicon radiation detectors, but the function of this contribute to the loss of bond strength or the increase in bond contact is not yet fully explored. One part problem is the rrle of the resistance normally encountered during the seal cycle. Also shown was metal films used as external contacts to the amorphous film. In this the aluminium diffusion rate to be significantly retarded in the gold paper we investigate the function of different contacting metals, such alloy as compared to the standard gold. A failure mechanism was as Au, AI, Cr by measuring the I-V characteri.stics of sandwich structures with two metals on both sides of the amorphous evaporated proposed. Ge film (of typical thickness l#m). Cadmium telluride nuclear radiation detectors P. HOSCHL, P. POL[VKA, V. PROSSER, M. SKRIVANKOVA and M. V I D R A Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.279-281 (1977). c a d m i u m telluride, has an excellent gamma-ray stopping power compared with traditional detector materials like Ge and Si. The growth of CdTe from Te solvent was used to obtain material for nuclear radiation detectors. The quality of detectors was tested by 5rCo and 2*~Am. Total resolution is approximately 7keV (FWHM) for 122keV gamma STCo and 5keV (FWHM) for 59keV gamma 24~Am.
Anodic oxidation and MOS devices of GaAs and GaP T. IKOMA, H. T O K U D A , H. YOKOMIZO and Y. ADACHI Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.475-479 (1977). Chemical and electric properties of the anodic oxide films of GaAs and G a P are investigated under various annealing conditions. Analysis of the oxidation current proves that the oxide grows at constant field condition on p-GaAs and at constant resistivity condition on n-GaAs under the pseudo constnt voltage biasing. Proper annealing improves C-V curves of a p-GaAs MOS diode to almost the ideal case, while the improvement is small for an n-GaAs diode. It is found that the change of the C-V and G-V curves is influenced by annealing temperatures rather than by annealing gases. Effects of the bias-temperature (BT) treatment are also shown. Lead-indium for controlled-collapse chip joining L. S. GOLDMANN, R. J. H E R D Z I K , N. G. KOOPMAN and V. C. M A R C O T r E Proc. Electron. Components Conf., Arlington, Va., p.25 (May 1977). A major requirement of controlled-coUap~e flip-chip, solder interconnections, shared by most other electronic interconnections, is the ability to absorb strains arising from the thermal mismatch of unlike materials within the package. In particular, mismatch between the alumina substrate and the silicon chip produces a shearing motion on each joint each time the machine is turned on or off, and to a secondary extent each time the ship is powered or addressed. An inability to withstfind mismatch strains leads to mechanical fracture and premature end of life. Among the many methods for increasing 40
High purity chemicals in semicon production K. G. CLARK, E. M. J U L E F F a n d S. FAWCE'Vr Electron. Prod., p.43 (April 1977). In the field of wet processing chemicals 'electronic' or 'semiconductor" grade materials have been available for a number of years and have been widely used in the mieroelectronics industry especially by the manufacturers of MOS and surface effect integrated circuits. These chemicals have been manufactured worldwide by leading chemical companies in bulk quantities and in this bulk state have been able to meet their published specifications however, in the methods employed for bottling and in the bottles themselves inorganic solids and metallic materials have been added to the liquid chemicals often in significant quantities of impurities and being measured at many hundred to tens of thousands of particles at a whole range of sizes from sub-micron to 50p.m or greater particle size and at impurity levels of 1.00 to 1.00ppm of a given inorganic impurity. Some of these chemicals also contain the origin salts at a relatively high impurity level, for intance, ammonium fluoride solution (the largest volume component in SiOz etchants) normally contains several ppm of solid calcium salt in its originating raw material calcium fluoride. A study has been made of both the particulate matter found in bottled 'electronic/semiconductor' grade chemicals and the impurity levels found both of which deviate in all cases from the manufacturers specification for the chemical solution. Influence of temperature on the structure and properties of an anodised native GaAs oxide T. ISHII and B. JEPPSSON Proceedings of the 8th Conference (1976 International) on Solid State Devices, Tokyo, 1976; Japanese Journal of Applied Physics, 16, Supplement 16-1, pp.471-474 (1977). The influence of temperature on the properties, the composition and the structure of the anodically grown native GaAs oxide is investigated. The oxide is very stable below 35ff'C. Above 350°C, the oxide begins to decompose first by releasing water. The oxide decomposes most rapidly around 450°C mainly by vaporising water and arsenic monoxide. By decomposition, drastic changes of oxide properties and composition are observed. The oxide decomposition is completed at 700°C resulting in pure gallium oxide. By coating SiO2 film on top of the anodised oxide film, GaAs is possible to be heat-treated at 800°C for 2 hours without any degradation of the GaAs surface.