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Measuring thermal resistance is the key to a cool semiconductor
228
World Abstracts on Microelectronics and Reliability
An optical scanning system for semiconductor junction examination. A. SINGMIN. Microelectron. Reliab. 17, 399 (1978). This paper describes an optical scanning system, used in the examination of semiconductor junction devices. A small cathode ray tube provides a scanning raster of approximately 250 lines, which is focused onto the device to be examined. As a result of the light striking the surface of the device, photocurrents are generated, and via suitable amplification, are used to modulate the brightness of a monitor cathode ray tube. Both the light source and monitor c.r.t.'s are fed with the same scanning timebase waveforms, and the resultant image obtained on the monitor tube corresponds to the junction areas on the surface of the device. This optical scanning system thus provides a visible image of the active regions of a semiconductor device and examples are given of both good and failed devices. Measuring thermal resistance is the key to a cool semiconductor. BERNARD S. SIEGEL. Electronics p. 121 (6 July 1978). To improve performance, reliability, and yield of integrated circuits, knowledge of thermal design considerations and of measurement techniques is a must for the user, as well as the manufacturer, of semiconductor devices. Environmental tests for connectors and contact materials: An evaluation of a method involving sulfur dioxide. MORTON ANTLER and JERRY J. DUNBAR. IEEE Trans. Components, Hybrids, Manufacturing Technology C H M T - I , (1) 17 (March 1978). The need for environmental tests for the evaluation of contact materials, to assist in the development of connector designs, for the qualification of manufactured product, and in basic studies of surface chemistry and the properties of films is widely recognized. However, studies of the tests themselves, including methodology, reproducibility, and their relationship to field environments have not had the attention they deserve. As a result, although m a n y methods are employed, there is little confidence in their relevance. Some c o m m o n fallacies in the design of environmental tests and in the interpretation of their results are reviewed. One method having wide use for electronic connectors involves exposure in a chamber having an atmosphere of 25 ppm SO2 at 75 percent relative humidity and 25 ° for 20 days. The method is known as the l~dustrial Atmosphere
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Microprocessor device reliability. EUGENE R. HNATEK. Microelectron. Reliab. 17, 379 (1978). The increased usage of microprocessors has brought forth many questions regarding the reliability of these devices. The two year maturation process for the 4k dynamic RAM underscored the importance of reliability for LSI devices. This paper puts the topic of microprocessor reliability into proper perspective with a discussion of device failure modes, test techniques, inhouse test and field experience. LSI tester gets microprocessors to generate their own test patterns. STEPHEN BISSET. Electronics p. 14l (25 May 1978). By deriving the test pattern from a device identical to the one under test, a general-purpose benchtop unit can handle different types of microprocessors and peripheral chips at actual system speeds. Speech network maintenance by fault observation and evaluation. A. BlflCHHEISTER, J. DUNESME and W. LINGELBACH. Eleetl Corn,nun. 53, (1) 63 (1978). The most c o m m o n method of speech network maintenance in space division
Test ./br Contacts and Connectors, British Standards 2011 : Part 2Kb: 1970, and is similar to International Electrotechnical Commission Test Kc, Publication 68-2-42 issued in 1976. This test was examined with a wide range of base metals, gold alloy and palladium alloy clad materials, and gold electrodeposits having a range of porosities on different underplatings with a sharp line of demarcation exposing a variety of base substrates, as well as with several connectors. Corrosion rates and the contact resistances of corrosion,products were determined by probing. The contact resistances of connectors that had been aged in both the mated and tmmated conditions were measured. It was found that the test was highly repeatable provided certain precautions were taken. It is useful for assessing the probable dependence of connector performance on the porosity in gold plated contacts on copper, copper alloys, and nickel for extended service in polluted atmospheres above the m i n i m u m relative humidity (ca. 70 percent) required for rapid corrosion that might occur in some industrial locations. However, the test is too severe for separable connectors and contact materials that will serve at benign conditions, such as indoors with relative humidity controlled to low levels, and so may encourage overdesign and more costly materials practices than are otherwise required. The effect of hot spots on the noise characteristic of largearea bipolar transistors. S B. SHACTER, A. VAN DER ZIEI., E. R. CHENETTE and A. D. SUTHERLAND. Solid-St. Electro,. 21,599 ll978). Measurements indicate that when hot spots are formed in large-area silicon power transistors, the 1/I noise increases and a new noise component with a 1,{I: spectrum shows up. The increase in 1/.1 noise is attributed to the decrease in effective device area when the hot spot is formed. The noise with a 1,(f 2 spectrum is attributed to a thermal feedback effect in the hot spot. The temperature stability of punch-through diodes. D. DE COGAN and TH. G. VAN DE ROER. Solid-St. Electrml. 21, 897 (19781. There is a single value of current, where the temperature dependence of voltage across a punchthrough diode is close to zero over a wide temperature range. The sign of the dependence is negative below this value and positive above. A model which accounts for this behaviour in terms of the injection mechanism gives excellent agreement with experiment.
MAINTENANCE
AND
REDUNDANCY
switching SPC telephone exchanges is based on periodic execution of systematic test programs. However, an alternative method is described for M E T A C O N T A * L exchanges, based on tests which are integrated into the normal call processing procedures. When a fault occurs the results of these tests are stored: subsequently, analysis of these results quickly and accurately locates the failing equipment even when the faults are sporadic.
Advanced operations and maintenance facilities for telephone networks. J. W. DICKER, J. F. WEST and U VAN Os. Electl Commun. 53, (1) 44 (1978). Increasing worldwide penetration of SPC and other advanced electronic switching systems, of which the M E T A C O N T A * 10CN exchange is an example, with their improved reliability and extensive operational facilities, has resulted in a trend towards unattended exchanges and the centralization of maintenance and operations functions. ITT has now made a detailed study of how best to exploit the capabilities of the new switching system in a centralized maintenance and operations environment. This
World Abstracts on Microelectronics and Reliability
An optical scanning system for semiconductor junction examination. A. SINGMIN. Microelectron. Reliab. 17, 399 (1978). This paper describes an optical scanning system, used in the examination of semiconductor junction devices. A small cathode ray tube provides a scanning raster of approximately 250 lines, which is focused onto the device to be examined. As a result of the light striking the surface of the device, photocurrents are generated, and via suitable amplification, are used to modulate the brightness of a monitor cathode ray tube. Both the light source and monitor c.r.t.'s are fed with the same scanning timebase waveforms, and the resultant image obtained on the monitor tube corresponds to the junction areas on the surface of the device. This optical scanning system thus provides a visible image of the active regions of a semiconductor device and examples are given of both good and failed devices. Measuring thermal resistance is the key to a cool semiconductor. BERNARD S. SIEGEL. Electronics p. 121 (6 July 1978). To improve performance, reliability, and yield of integrated circuits, knowledge of thermal design considerations and of measurement techniques is a must for the user, as well as the manufacturer, of semiconductor devices. Environmental tests for connectors and contact materials: An evaluation of a method involving sulfur dioxide. MORTON ANTLER and JERRY J. DUNBAR. IEEE Trans. Components, Hybrids, Manufacturing Technology C H M T - I , (1) 17 (March 1978). The need for environmental tests for the evaluation of contact materials, to assist in the development of connector designs, for the qualification of manufactured product, and in basic studies of surface chemistry and the properties of films is widely recognized. However, studies of the tests themselves, including methodology, reproducibility, and their relationship to field environments have not had the attention they deserve. As a result, although m a n y methods are employed, there is little confidence in their relevance. Some c o m m o n fallacies in the design of environmental tests and in the interpretation of their results are reviewed. One method having wide use for electronic connectors involves exposure in a chamber having an atmosphere of 25 ppm SO2 at 75 percent relative humidity and 25 ° for 20 days. The method is known as the l~dustrial Atmosphere
3. C I R C U I T
AND
SYSTEMS
RELIABILITY,
Microprocessor device reliability. EUGENE R. HNATEK. Microelectron. Reliab. 17, 379 (1978). The increased usage of microprocessors has brought forth many questions regarding the reliability of these devices. The two year maturation process for the 4k dynamic RAM underscored the importance of reliability for LSI devices. This paper puts the topic of microprocessor reliability into proper perspective with a discussion of device failure modes, test techniques, inhouse test and field experience. LSI tester gets microprocessors to generate their own test patterns. STEPHEN BISSET. Electronics p. 14l (25 May 1978). By deriving the test pattern from a device identical to the one under test, a general-purpose benchtop unit can handle different types of microprocessors and peripheral chips at actual system speeds. Speech network maintenance by fault observation and evaluation. A. BlflCHHEISTER, J. DUNESME and W. LINGELBACH. Eleetl Corn,nun. 53, (1) 63 (1978). The most c o m m o n method of speech network maintenance in space division
Test ./br Contacts and Connectors, British Standards 2011 : Part 2Kb: 1970, and is similar to International Electrotechnical Commission Test Kc, Publication 68-2-42 issued in 1976. This test was examined with a wide range of base metals, gold alloy and palladium alloy clad materials, and gold electrodeposits having a range of porosities on different underplatings with a sharp line of demarcation exposing a variety of base substrates, as well as with several connectors. Corrosion rates and the contact resistances of corrosion,products were determined by probing. The contact resistances of connectors that had been aged in both the mated and tmmated conditions were measured. It was found that the test was highly repeatable provided certain precautions were taken. It is useful for assessing the probable dependence of connector performance on the porosity in gold plated contacts on copper, copper alloys, and nickel for extended service in polluted atmospheres above the m i n i m u m relative humidity (ca. 70 percent) required for rapid corrosion that might occur in some industrial locations. However, the test is too severe for separable connectors and contact materials that will serve at benign conditions, such as indoors with relative humidity controlled to low levels, and so may encourage overdesign and more costly materials practices than are otherwise required. The effect of hot spots on the noise characteristic of largearea bipolar transistors. S B. SHACTER, A. VAN DER ZIEI., E. R. CHENETTE and A. D. SUTHERLAND. Solid-St. Electro,. 21,599 ll978). Measurements indicate that when hot spots are formed in large-area silicon power transistors, the 1/I noise increases and a new noise component with a 1,{I: spectrum shows up. The increase in 1/.1 noise is attributed to the decrease in effective device area when the hot spot is formed. The noise with a 1,(f 2 spectrum is attributed to a thermal feedback effect in the hot spot. The temperature stability of punch-through diodes. D. DE COGAN and TH. G. VAN DE ROER. Solid-St. Electrml. 21, 897 (19781. There is a single value of current, where the temperature dependence of voltage across a punchthrough diode is close to zero over a wide temperature range. The sign of the dependence is negative below this value and positive above. A model which accounts for this behaviour in terms of the injection mechanism gives excellent agreement with experiment.
MAINTENANCE
AND
REDUNDANCY
switching SPC telephone exchanges is based on periodic execution of systematic test programs. However, an alternative method is described for M E T A C O N T A * L exchanges, based on tests which are integrated into the normal call processing procedures. When a fault occurs the results of these tests are stored: subsequently, analysis of these results quickly and accurately locates the failing equipment even when the faults are sporadic.
Advanced operations and maintenance facilities for telephone networks. J. W. DICKER, J. F. WEST and U VAN Os. Electl Commun. 53, (1) 44 (1978). Increasing worldwide penetration of SPC and other advanced electronic switching systems, of which the M E T A C O N T A * 10CN exchange is an example, with their improved reliability and extensive operational facilities, has resulted in a trend towards unattended exchanges and the centralization of maintenance and operations functions. ITT has now made a detailed study of how best to exploit the capabilities of the new switching system in a centralized maintenance and operations environment. This