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A metallurgical analysis of stress-corrosion cracking of Kovar package lead
World Abstracts on Microelectronics and Reliability MOS devices. This failure analysis capacity has enhanced the ability to control the MOS process.
Accelerated lifetesting and failure modes of thin film W contacts on Si-Ge Thermoelectric alloys. J. N. SWEET. Proc. IEEE Reliab. Physics Syrup. April 2-4, 1974. p. 196. The stability of sputtered thin film W contacts on heavily doped Si-Ge alloy has been determined from measurements of contact resistance versus time for aging temperatures in the range 550-725°C. Contact failure time has been found to obey an Arrhenius type relation with an activation energy of 76+5 kcal/mole and a projected lifetime of over ten years at temperatures below 450°C. Contact resistance remains approx, constant for the first 80% of contact lifetime and then increases rapidly through several orders of magnitude. These large contact increases are accompanied by loss of contact adhesion and buckling. Comparison of this data with that from diffusion experiments indicates that the activation energy for contact failure is comparable with that for the initial stages of WSi2 layer growth in W-Si systems. Niehrome resistor failures as studied by X-ray photoelectron spectroscopy (XPS or ESCA). W. E. BAITINGER, N. WINOGRAD, J. W. AMY and J. A. MUNARIN. Proc. IEEE Reliability Physics Syrup. April 2-4, 1974. p. 1. Depth profiles yielding both information on oxidation state and elemental composition have been obtained for model nichrome films by using X-ray Photo-electron Spectroscopy and argon ion sputtering. Evidence is presented showing the formation of thin insulating films at the interface between two metals caused by solid state reactions occurring between metals and metal oxides. Sensitivity of current pulse buro-out testing to the geometry of defects in uluminium metullization. H. S. GUREV. Proc. IEEE Reliability Physics Syrup. April 2-4, 1974. p. 187. Current pulses, with power levels sufficient to burn out metal stripes in the 30-1000 nsec pulse time range, were found to overcome lateral heat losses and permit the detection of metallizatiou step coverage defects for the several cases of practical interest investigated. In the most extreme case, a sharp groove about 400 A wide, extending to within 650 A of the bottom of 9000 A thick aluminum metallization, was easily detected by pulse testing. Threshold energy effect on avalanche breakdown voltage in semiconductor junctions. Y. OKUTO and C. R. CROWELL. Solid-St. Electron. 18, 161 (1975). The band bending for avalanche breakdown in semiconductor junctions and its temperature dependence are predicted taking account of threshold energy effects on the ionization process in semiconductors. Where experimental results exist, the theoretical predictions and experimental results are in excellent agreement. In the high electric field region inclusion of both bulk and boundary threshold energy effects is essential. The predictions were based on exact solutions in the nonlocalized ionization coefficient formulation developed by Okuto and Crowell who showed that ionization coefficients as usually understood are functions of both electric field and position in a device. Predictions for abrupt and p--i-n junctions in Ge, Si, GaAs and GaP are presented. Interface Instabilities. E. H. NICHOLLIAN. Prec. 1EEE Reliability Physics Symposium. April 2-4, 1974. p. 267. A review will be given of the instabilities of MOS field effect transistors caused by the time variation of the electrical properties of the Si-SiO2 interface during device life. Changes in interface properties can be accelerated by heating without bias and heating with negative bias apM R - - V o l . 14, NO. 4
B
337
plied to the gate. The specific topics discussed will include how fixed oxide charge and interface trap densities change with accelerated aging, the effects of these changes on the characteristics of MOS field effect transistors, and how these changes can be minimized to achieve better reliability.
S O A R - - t h e basis for reliable power circuit design. Part h Power transistor limitations and ratings. Philips Electron. Applications Bull. 32, 137 (1973). The SOAR method of specification has been made possible by improved understanding of power transistor failure mechanisms. In essence, this method of specification unites the various transistor limitations. Part I of this article reviews the various failure mechanisms, particularly the phenomenon of second breakdown. The philosopy behind the Philips SOAR specifications is explained, and the quality control and inspection methods used to define the SOAR for any particular type of transistor are described. There is also a discussion of the reverse-biased condition and the methods by which reverse-bias ratings are set and maintained. In Part II the recommended methods of using Philips SOAR charts will be described in detail, as will procedures for determining the thermal operating conditions of transistors. The mechanism of r.f. spike burn-out in Schottky barrier microwave mixers. P. H. GERZON, J. W. BARNES, D. W. WAITE and D. C. NORTHROP. Solid-St. Electron. 18, 343 (1975). It is established that r.f. spike burnout in Schottky barrier microwave mixers is caused by localised heating to a temperature in excess of a critical value dependent on the metal used to form the barrier. By a suitable choice of metal, devices have been made which can withstand spike energies in excess of 1 erg. There seems no reason why advances in manufacturing technology should not improve this performance. Failure mechanisms in gold metullized sealed junction devices. E. B. HAKIM and J. R. SHAPPIRIO.Solid-St. Tech. April 1975. p. 66. Two different types of p-n-p transistors and an integrated circuit, which were fabricated using silicon nitride and gold contact metallization, failed while on test in the Panama Canal Zone. Failure analysis indicated that the following failure mechanisms and problem areas were present in these units: (1) gold corrosion resulting in dendritic growth; (2) titanium over nitride between conductors; (3) exposed high concentrations of platinum; (4) inability of glass to adhere to gold metallization and to seal the device. These conditions occur as a result of both poor quality control and basic process limitations. A metallurgical analysis of stress-corrosion cracking of Kovar package lead. L. J. WEIRICK. Solid-St. Tech. March 1975. p. 25. Scanning electron microscopy and metallographic analysis indicated that stress-corrosion cracking was responsible for some Kovar leads completely breaking away from integrated circuit packages following a moisture-resistance test. The cracks were found to have been initiated intergranularly and propagated transgranularly. Further analysis showed that the following factors accelerated the stress-corrosion cracking: (1) the presence of a tensile stress, (2) insufficient nickel plating on the Kovar, (3) penetration of the Kovar grain boundaries by copper and (4) the presence of contaminants containing free chloride. Radiation-stimulated tailure mechanism in a dielectrically isolated integrated circuit. J. L. AZAREWlCZ and T. F. WROBEL. IEEE Trans. Pans, Hybrids, Packaging PHP10, 159 (1974). An apparent latchup condition was observed in a hi-rel dielectrically isolated integrated circuit.
Accelerated lifetesting and failure modes of thin film W contacts on Si-Ge Thermoelectric alloys. J. N. SWEET. Proc. IEEE Reliab. Physics Syrup. April 2-4, 1974. p. 196. The stability of sputtered thin film W contacts on heavily doped Si-Ge alloy has been determined from measurements of contact resistance versus time for aging temperatures in the range 550-725°C. Contact failure time has been found to obey an Arrhenius type relation with an activation energy of 76+5 kcal/mole and a projected lifetime of over ten years at temperatures below 450°C. Contact resistance remains approx, constant for the first 80% of contact lifetime and then increases rapidly through several orders of magnitude. These large contact increases are accompanied by loss of contact adhesion and buckling. Comparison of this data with that from diffusion experiments indicates that the activation energy for contact failure is comparable with that for the initial stages of WSi2 layer growth in W-Si systems. Niehrome resistor failures as studied by X-ray photoelectron spectroscopy (XPS or ESCA). W. E. BAITINGER, N. WINOGRAD, J. W. AMY and J. A. MUNARIN. Proc. IEEE Reliability Physics Syrup. April 2-4, 1974. p. 1. Depth profiles yielding both information on oxidation state and elemental composition have been obtained for model nichrome films by using X-ray Photo-electron Spectroscopy and argon ion sputtering. Evidence is presented showing the formation of thin insulating films at the interface between two metals caused by solid state reactions occurring between metals and metal oxides. Sensitivity of current pulse buro-out testing to the geometry of defects in uluminium metullization. H. S. GUREV. Proc. IEEE Reliability Physics Syrup. April 2-4, 1974. p. 187. Current pulses, with power levels sufficient to burn out metal stripes in the 30-1000 nsec pulse time range, were found to overcome lateral heat losses and permit the detection of metallizatiou step coverage defects for the several cases of practical interest investigated. In the most extreme case, a sharp groove about 400 A wide, extending to within 650 A of the bottom of 9000 A thick aluminum metallization, was easily detected by pulse testing. Threshold energy effect on avalanche breakdown voltage in semiconductor junctions. Y. OKUTO and C. R. CROWELL. Solid-St. Electron. 18, 161 (1975). The band bending for avalanche breakdown in semiconductor junctions and its temperature dependence are predicted taking account of threshold energy effects on the ionization process in semiconductors. Where experimental results exist, the theoretical predictions and experimental results are in excellent agreement. In the high electric field region inclusion of both bulk and boundary threshold energy effects is essential. The predictions were based on exact solutions in the nonlocalized ionization coefficient formulation developed by Okuto and Crowell who showed that ionization coefficients as usually understood are functions of both electric field and position in a device. Predictions for abrupt and p--i-n junctions in Ge, Si, GaAs and GaP are presented. Interface Instabilities. E. H. NICHOLLIAN. Prec. 1EEE Reliability Physics Symposium. April 2-4, 1974. p. 267. A review will be given of the instabilities of MOS field effect transistors caused by the time variation of the electrical properties of the Si-SiO2 interface during device life. Changes in interface properties can be accelerated by heating without bias and heating with negative bias apM R - - V o l . 14, NO. 4
B
337
plied to the gate. The specific topics discussed will include how fixed oxide charge and interface trap densities change with accelerated aging, the effects of these changes on the characteristics of MOS field effect transistors, and how these changes can be minimized to achieve better reliability.
S O A R - - t h e basis for reliable power circuit design. Part h Power transistor limitations and ratings. Philips Electron. Applications Bull. 32, 137 (1973). The SOAR method of specification has been made possible by improved understanding of power transistor failure mechanisms. In essence, this method of specification unites the various transistor limitations. Part I of this article reviews the various failure mechanisms, particularly the phenomenon of second breakdown. The philosopy behind the Philips SOAR specifications is explained, and the quality control and inspection methods used to define the SOAR for any particular type of transistor are described. There is also a discussion of the reverse-biased condition and the methods by which reverse-bias ratings are set and maintained. In Part II the recommended methods of using Philips SOAR charts will be described in detail, as will procedures for determining the thermal operating conditions of transistors. The mechanism of r.f. spike burn-out in Schottky barrier microwave mixers. P. H. GERZON, J. W. BARNES, D. W. WAITE and D. C. NORTHROP. Solid-St. Electron. 18, 343 (1975). It is established that r.f. spike burnout in Schottky barrier microwave mixers is caused by localised heating to a temperature in excess of a critical value dependent on the metal used to form the barrier. By a suitable choice of metal, devices have been made which can withstand spike energies in excess of 1 erg. There seems no reason why advances in manufacturing technology should not improve this performance. Failure mechanisms in gold metullized sealed junction devices. E. B. HAKIM and J. R. SHAPPIRIO.Solid-St. Tech. April 1975. p. 66. Two different types of p-n-p transistors and an integrated circuit, which were fabricated using silicon nitride and gold contact metallization, failed while on test in the Panama Canal Zone. Failure analysis indicated that the following failure mechanisms and problem areas were present in these units: (1) gold corrosion resulting in dendritic growth; (2) titanium over nitride between conductors; (3) exposed high concentrations of platinum; (4) inability of glass to adhere to gold metallization and to seal the device. These conditions occur as a result of both poor quality control and basic process limitations. A metallurgical analysis of stress-corrosion cracking of Kovar package lead. L. J. WEIRICK. Solid-St. Tech. March 1975. p. 25. Scanning electron microscopy and metallographic analysis indicated that stress-corrosion cracking was responsible for some Kovar leads completely breaking away from integrated circuit packages following a moisture-resistance test. The cracks were found to have been initiated intergranularly and propagated transgranularly. Further analysis showed that the following factors accelerated the stress-corrosion cracking: (1) the presence of a tensile stress, (2) insufficient nickel plating on the Kovar, (3) penetration of the Kovar grain boundaries by copper and (4) the presence of contaminants containing free chloride. Radiation-stimulated tailure mechanism in a dielectrically isolated integrated circuit. J. L. AZAREWlCZ and T. F. WROBEL. IEEE Trans. Pans, Hybrids, Packaging PHP10, 159 (1974). An apparent latchup condition was observed in a hi-rel dielectrically isolated integrated circuit.