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High tensile strength thick-film silver-palladium metallizations
186
World Abstracts on Microelectronics and Reliability
perturbed host lattice density of states (additivity of Green's function).
Discharge of MNOS structures at elevated temperatures. LEIF LUNDKVIST.CHRISTER SVENSSONand BERTIL HANSSON. Solid-State Electronics 19, 221 (1976). The discharge behavior of MNOS structures without voltage applied, is investigated at temperatures from 25 to 300°C, for times from 10 min to about 1 week. The observed discharge behavior is explained by a theoretical model, including two discharge processes. The two processes are direct tunneling from traps and thermal excitation of these traps. It is shown that static retention times of more than 10 yr at 85~C is attainable. Also, discharge with voltage applied is investigated and shown to agree with the model when the voltage is small enough.
Fabrication and characteristics of MOS-FET's incorporating anodic aluminum oxide in the gate structure. R. K. RAYMOND and MUKUNDA B. DAS. Solid-State Eh,ctronic,s 19, 181 (1976). Anodic aluminum oxide films have been grown by means of a simple process which is compatible with the existing planar silicon IC fabrication technology. Device structures have been fabricated and tested in order to demonstrate the usefulness of anodized layers of evaporated aluminum in a multiple layer metallization scheme.
Results of anodization of thin aluminum layers on a silicon substrate indicate complete conversion of aluminum into aluminum oxide and in addition, formation of a thin underlying layer of silicon dioxide. For the anodic aluminum oxide a growth rate of 11.5 A/volt at a current density of 0.5 mA/cm 2 has been found to produce quite satisfactory quality of insulting layers. Experimental results are presented illustrating the C-V and l.-V characteristics of p-channel M O S - F E T ' s with both the partially anodized stacked-gate structure and the over-anodized double-oxide layer gate structure.
Theoretical and experimental study of MOS transistors nonuniformly doped by SILOX technique. G. DOUCET, F. VAN DE WIELE and P. JESPERS. Solid-State Electronics 19, 191 (1976). A simple one-dimensional analytical model is presented for MOS transistors having a single type net impurity concentration substrate which is non uniform. Closed form expressions for the drain current, the threshold voltage, the pinchoff voltage and the low frequency small-signal parameters are given as a function of the equilibrium majority carrier distribution. Experimental results for n-channel MOS transistors nonuniformly doped by means of the SILOX process are presented and compared to the results of the theoretical model. The SILOX process is described in Section 5
8. THICK- AND THIN-FILM COMPONENTS, HYBRID CIRCUITS
AND MATERIALS Thick-film advances simplify complex hybrid module design. Prof. PETER KIRBY. Electronic Engineering p. 35 (March 1976). Hybrid thick-film circuits are now being produced in large quantities for many applications throughout the world. A superficial examination of product might suggest that there has been little change in the technology since the thick-film hybrid process originated in the early 1960s. This is incorrect. Every state of the production process has been the subject of significant improvement. A thick-film wide band amplifier. D. R. HETHERINTON. IERE Col!f. Hybrid Microelectronics, Loughborough p. 69. 9-11 Sept. 1975. The paper describes the conversion from printed circuit to thick-film hybrid circuit technology of a wide band amplifier used in the input of a video tape recorder, The amplifier specification is 14 dB gain from 40 to 860 mHz. The thick-film layout is described in detail and the performance differences between plastic 'T' pack active devices and naked chip epoxy bonded devices are shown. A fast thick-film amplifier. J. ROBERTSON and B. ANDERSON. IERE Coqfi Hybrid Microelectronics, Loughborough p. 77. 9 11 Sept. 1975, This paper describes a thick-film hybrid preamplifier which was produced as a joint venture between Nuclear Enterprises Limited and Edinburgh University. The preamplifier functioned as an amplifier with a 50fl input impedance between a photomultiplier tube and a discriminator stage. It was designed to provide a gain of 4 with a risetime < 1 nsec. Small size was dictated by transit time and capacitance considerations but also by the requirement to stack 8 preamplifier circuits vertically within a 1,35 in. (34.3 ram) wide NIMS module.
Thick-film directional coupler design--a comparison of theories. PETER L. BAINBRIDGEand RONALD J. ROBERTSON. IERE Co~f Hybrid Microelectronics, Loughborough p. 83. 9 11 Sept. 1975. The paper describes the design of 10 dB and 20 dB directional couplers using two different theories.
One method used computer programmes to determine the dimensions and the other used design data curves. The performance of the thick-film couplers in the frequency range 1 2 GHz is compared and various improvements are suggested.
High frequency characteristics of meandering line-resistors with regard to the design of thin-film circuits. H. GRUNDNER and H. FECHNER. IERE Conf. Hybrid Microelectronics. Loughborough p. 63.9-1t Sept. 1975. The paper describes the high frequency behaviour of meandering line-resistors manufactured in thin-film technology. By means of a developed lumped-distributed model the frequency characteristic of such resistors in an arbitrary rectangular area is computed. The results, which are in good agreement with the outcome of measurements are plotted in diagrams. For a given power requirement, resistor area, resistance valuc and a required limiting frequency one can get quickly the shape of the meandering lines, the resistor-line width and the number of squares for a resistor, fulfilling the required frequency-specification.
A hybrid thin-film multichannel biotelemetry transmitter. JOHN H. FILSHIE and IAIN J. MCGEE. IERE Conf. Hybrid Microelectronies, Loughborough p. 49. 9 11 Sept. 1975. The requirements of a modern biotelemetry system are discussed together with the problems of measuring biological parameters. Hybrid thin-film methods provide a good solution to the problem. Multi-channel F M / F M VHF radiotransmitters for measuring temperature and biopotentials have been designed and constructed. A radio-frequencyoperated switch is also described which allows implanted transmitters to be switched remotely.
A simple hybrid thick-film hand pass filter. D. P. HEYWOOD. IERE Conf. Hybrid Microelectronics, Loughborough p. 43. 9-11 Sept. 1975. It is shown that inductors can be replaced by a very simple form of gyrator for filters demanding only moderate values of Q, giving a saving in space and
World Abstracts on Microelectronics and Reliability cost. A particular filter is described which is over an order of magnitude smaller than an LCR equivalent.
High tensile strength thick-film silver-palladium metallizations. TREVOR H. LEMON IERE Confl Hybrid Microlectronics, Loughborough p. 23. 9 11 Sept. 1975. Soldered joints based upon conventional Ag Pd metallizations rapidly lose overall tensile strengths when the bonds are subjected to elevated temperatures. This degradation in bond strengths has been substantially arrested by selecting a glass for use in the metallizing composition with a softening point lying between the reduction temperature of A ~ PdO mixes and the standard peak firing temperature. In this way, it is possible to form glass-metal bonds which are subjected to the minimum of physical disturbances during normal processing schedules. These more coherent layers inhibit surface diffusion of the active species thereby limiting the rate at which brittle intermetallics are formed. A thick-film humidity sensor. N. D. CHANNON and P. G. BARNWELL. IERE Conf. Hybrid Microelectronics, Loughborough p. 57. 9 I I Sept. 1975. A humidity sensitive thickfilm paste has been developed which enables the fabrication of humidity transducers using standard thick-film processing equipment. The thick-film transducer is a capacitive device which is small, rugged and stable, yet has a last response time and is inexpensive to produce.
Comparative investigation of thick-film and thin-film components and M1C's up to 16 GHz. W, FUNK and W. SCHILZ. IERE Conf. Hybrid Microelectronics, Loughborough p. 95. 9 I I Sept. 1975. Two technologies can be applied for the fabrication of microwave integrated circuits: thick-film and thin-film technique. While thin-film has the advantage of excellent accuracy of the transmission line width and edge definition, thick film technique opens the possibility of direct integration of resistors and capacitors in the same fabrication process. This can be a cost reduction factor in mass production. However, the limited accuracy of thick film limits the upper frequency of the circuit. Substrate bowing in thick-film multilayered circuits. J. SAVAGE and N. DAVEY. IERE Conf. Hybrid Microelectronics, Loughborough p. 17. 9-11 Sept. 1975. This paper describes the distortion of alumina substrates which occurs during thick-film multilayered circuit fabrication and compares the effect of a range of commercial insulant materials. The distortion is shown, by dilatometry and direct observation, to be due to thermal expansion mismatch between the insulant and the alumina and the paper is accompanied by a time lapse cine film which demonstrates the progress of bowing during heating and cooling cycles. An estimate is made of the stress levels in the insulants and the possible effect of these stresses on the reliability of the circuit array is considered. Technological teaching of hybrid microeleetronies (thickfilm). Y. LEROY, M. DESCAMPSand M. VERNET. IERE Conf. Hybrid Microelectronics, Loughborough p. 131. 9-11 Sept. 1975. Principles and fabrication of hybrid circuits (thickfilm) have been taught in the Department Genie Electrique (I.U.T. LILLE) since 1973. The purpose of this paper is to report our experience with this teaching and to give a few details about the devices which were studied and achieved by the students. Thick-film research in a university environment. Prof. D. S. CAMPBELLand P. L. MORAN. IERE Co~f Hybrid Microelectronics. Loughborough p. 135. 9 11 Sept. 1975. This paper is introduced with a brief survey of the background in which we have developed our thick film activities at
m.r. 15/3 ~
187
Loughborough University. As well as outlining the research activities of the department, particularly with regard to our strengths in sonar and digital communications, mention is also made of the type of degree courses which we have, which include the possibility of the third year being spent in industry and a project in the final year (or fourth year) which is linked if at all possible, to the activity in which the student has been involved during his industrial year. Another feature of the department is that we teach Electrical Component Technology as an option for our final year students. Arising from this background, several undergraduate final year projects in thick-film technology are described, including work on laser trimming of resistors and the use of thick films for constructing a delta modulator circuit. The conclusion is reached that thick films are now in a position to offer a very useful facility to electrical and electronic engineering departments where circuits are continually being required for special applications and where the teaching element of the activity can provide a very useful background to students who are interested in component technology.
The hybrid microelectronics explosion in Finland. EERO JARVlNEN. IERE Conf. Hybrid Microelectronics, Loughborough p. 127. 9 11 Sept. 1975. The present paper describes the success with which thick-film hybrid technology has been developed in Finland as a result of close co-operation between the research establishment and industry. In particular it describes the active role of the university in encouraging industry to make use of this technology in its production. A range of automatic finishing machines for thin-film hybrid circuits. GORDON H. YOUNG. IERE Conf. Hybrid Microelectronics, Loughborough p. 241. 9 11 Sept. 1975. The paper deals with a line of machines specifically designed to automate as far as is practical a large in-house requirement for thin-film hybrid circuits used in the telephone industry. Handling innovations are described, and indications are given of production rates and yields. Some problems are discussed, and mention is also made of possible future developments to extend the use of the system. Conduction theory applied to thick-film resistors. ROBERT M. HILL. IERE Conf. Hybrid Microelectronics, Loughborough p. 251.9-11 Sept. 1975. Examination of the specification for a resistor is used to determine the physical requirements and it is shown that these can be met in disordered structures. Comparison of the theoretical characteristics of hopping transport in a narrow band of localised states with the experimentally determined characteristics of a range of thick-film and carbon resistors indicates that the critical features of hopping transport can be observed. Automatic manufacture of custom hybrid microelectronic circuits. ROGER F. RUSSELLand RICHARD THOMPSON. IERE Conf. Hybrid Microelectronics, Loughborough p. 159.9-11 Sept. 1975. The areas of application of hybrid microelectronics have to date been limited in general by economic considerations. Sophisticated electronic systems require considerable design engineering, and conventional hybrid assemblies use labour-intensive techniques. Automation applied to the manufacture of hybrid circuits can significantly improve productivity, and extend the area of application. A technology for high speed computer systems. S. HOLLOCK, D. J. KINNIMENT and N. V. MARTON. IERE Conf. Hybrid Microelectronics, Loughborough p. 143. 9-11 Sept. 1975. This paper describes a technology developed to reduce the
World Abstracts on Microelectronics and Reliability
perturbed host lattice density of states (additivity of Green's function).
Discharge of MNOS structures at elevated temperatures. LEIF LUNDKVIST.CHRISTER SVENSSONand BERTIL HANSSON. Solid-State Electronics 19, 221 (1976). The discharge behavior of MNOS structures without voltage applied, is investigated at temperatures from 25 to 300°C, for times from 10 min to about 1 week. The observed discharge behavior is explained by a theoretical model, including two discharge processes. The two processes are direct tunneling from traps and thermal excitation of these traps. It is shown that static retention times of more than 10 yr at 85~C is attainable. Also, discharge with voltage applied is investigated and shown to agree with the model when the voltage is small enough.
Fabrication and characteristics of MOS-FET's incorporating anodic aluminum oxide in the gate structure. R. K. RAYMOND and MUKUNDA B. DAS. Solid-State Eh,ctronic,s 19, 181 (1976). Anodic aluminum oxide films have been grown by means of a simple process which is compatible with the existing planar silicon IC fabrication technology. Device structures have been fabricated and tested in order to demonstrate the usefulness of anodized layers of evaporated aluminum in a multiple layer metallization scheme.
Results of anodization of thin aluminum layers on a silicon substrate indicate complete conversion of aluminum into aluminum oxide and in addition, formation of a thin underlying layer of silicon dioxide. For the anodic aluminum oxide a growth rate of 11.5 A/volt at a current density of 0.5 mA/cm 2 has been found to produce quite satisfactory quality of insulting layers. Experimental results are presented illustrating the C-V and l.-V characteristics of p-channel M O S - F E T ' s with both the partially anodized stacked-gate structure and the over-anodized double-oxide layer gate structure.
Theoretical and experimental study of MOS transistors nonuniformly doped by SILOX technique. G. DOUCET, F. VAN DE WIELE and P. JESPERS. Solid-State Electronics 19, 191 (1976). A simple one-dimensional analytical model is presented for MOS transistors having a single type net impurity concentration substrate which is non uniform. Closed form expressions for the drain current, the threshold voltage, the pinchoff voltage and the low frequency small-signal parameters are given as a function of the equilibrium majority carrier distribution. Experimental results for n-channel MOS transistors nonuniformly doped by means of the SILOX process are presented and compared to the results of the theoretical model. The SILOX process is described in Section 5
8. THICK- AND THIN-FILM COMPONENTS, HYBRID CIRCUITS
AND MATERIALS Thick-film advances simplify complex hybrid module design. Prof. PETER KIRBY. Electronic Engineering p. 35 (March 1976). Hybrid thick-film circuits are now being produced in large quantities for many applications throughout the world. A superficial examination of product might suggest that there has been little change in the technology since the thick-film hybrid process originated in the early 1960s. This is incorrect. Every state of the production process has been the subject of significant improvement. A thick-film wide band amplifier. D. R. HETHERINTON. IERE Col!f. Hybrid Microelectronics, Loughborough p. 69. 9-11 Sept. 1975. The paper describes the conversion from printed circuit to thick-film hybrid circuit technology of a wide band amplifier used in the input of a video tape recorder, The amplifier specification is 14 dB gain from 40 to 860 mHz. The thick-film layout is described in detail and the performance differences between plastic 'T' pack active devices and naked chip epoxy bonded devices are shown. A fast thick-film amplifier. J. ROBERTSON and B. ANDERSON. IERE Coqfi Hybrid Microelectronics, Loughborough p. 77. 9 11 Sept. 1975, This paper describes a thick-film hybrid preamplifier which was produced as a joint venture between Nuclear Enterprises Limited and Edinburgh University. The preamplifier functioned as an amplifier with a 50fl input impedance between a photomultiplier tube and a discriminator stage. It was designed to provide a gain of 4 with a risetime < 1 nsec. Small size was dictated by transit time and capacitance considerations but also by the requirement to stack 8 preamplifier circuits vertically within a 1,35 in. (34.3 ram) wide NIMS module.
Thick-film directional coupler design--a comparison of theories. PETER L. BAINBRIDGEand RONALD J. ROBERTSON. IERE Co~f Hybrid Microelectronics, Loughborough p. 83. 9 11 Sept. 1975. The paper describes the design of 10 dB and 20 dB directional couplers using two different theories.
One method used computer programmes to determine the dimensions and the other used design data curves. The performance of the thick-film couplers in the frequency range 1 2 GHz is compared and various improvements are suggested.
High frequency characteristics of meandering line-resistors with regard to the design of thin-film circuits. H. GRUNDNER and H. FECHNER. IERE Conf. Hybrid Microelectronics. Loughborough p. 63.9-1t Sept. 1975. The paper describes the high frequency behaviour of meandering line-resistors manufactured in thin-film technology. By means of a developed lumped-distributed model the frequency characteristic of such resistors in an arbitrary rectangular area is computed. The results, which are in good agreement with the outcome of measurements are plotted in diagrams. For a given power requirement, resistor area, resistance valuc and a required limiting frequency one can get quickly the shape of the meandering lines, the resistor-line width and the number of squares for a resistor, fulfilling the required frequency-specification.
A hybrid thin-film multichannel biotelemetry transmitter. JOHN H. FILSHIE and IAIN J. MCGEE. IERE Conf. Hybrid Microelectronies, Loughborough p. 49. 9 11 Sept. 1975. The requirements of a modern biotelemetry system are discussed together with the problems of measuring biological parameters. Hybrid thin-film methods provide a good solution to the problem. Multi-channel F M / F M VHF radiotransmitters for measuring temperature and biopotentials have been designed and constructed. A radio-frequencyoperated switch is also described which allows implanted transmitters to be switched remotely.
A simple hybrid thick-film hand pass filter. D. P. HEYWOOD. IERE Conf. Hybrid Microelectronics, Loughborough p. 43. 9-11 Sept. 1975. It is shown that inductors can be replaced by a very simple form of gyrator for filters demanding only moderate values of Q, giving a saving in space and
World Abstracts on Microelectronics and Reliability cost. A particular filter is described which is over an order of magnitude smaller than an LCR equivalent.
High tensile strength thick-film silver-palladium metallizations. TREVOR H. LEMON IERE Confl Hybrid Microlectronics, Loughborough p. 23. 9 11 Sept. 1975. Soldered joints based upon conventional Ag Pd metallizations rapidly lose overall tensile strengths when the bonds are subjected to elevated temperatures. This degradation in bond strengths has been substantially arrested by selecting a glass for use in the metallizing composition with a softening point lying between the reduction temperature of A ~ PdO mixes and the standard peak firing temperature. In this way, it is possible to form glass-metal bonds which are subjected to the minimum of physical disturbances during normal processing schedules. These more coherent layers inhibit surface diffusion of the active species thereby limiting the rate at which brittle intermetallics are formed. A thick-film humidity sensor. N. D. CHANNON and P. G. BARNWELL. IERE Conf. Hybrid Microelectronics, Loughborough p. 57. 9 I I Sept. 1975. A humidity sensitive thickfilm paste has been developed which enables the fabrication of humidity transducers using standard thick-film processing equipment. The thick-film transducer is a capacitive device which is small, rugged and stable, yet has a last response time and is inexpensive to produce.
Comparative investigation of thick-film and thin-film components and M1C's up to 16 GHz. W, FUNK and W. SCHILZ. IERE Conf. Hybrid Microelectronics, Loughborough p. 95. 9 I I Sept. 1975. Two technologies can be applied for the fabrication of microwave integrated circuits: thick-film and thin-film technique. While thin-film has the advantage of excellent accuracy of the transmission line width and edge definition, thick film technique opens the possibility of direct integration of resistors and capacitors in the same fabrication process. This can be a cost reduction factor in mass production. However, the limited accuracy of thick film limits the upper frequency of the circuit. Substrate bowing in thick-film multilayered circuits. J. SAVAGE and N. DAVEY. IERE Conf. Hybrid Microelectronics, Loughborough p. 17. 9-11 Sept. 1975. This paper describes the distortion of alumina substrates which occurs during thick-film multilayered circuit fabrication and compares the effect of a range of commercial insulant materials. The distortion is shown, by dilatometry and direct observation, to be due to thermal expansion mismatch between the insulant and the alumina and the paper is accompanied by a time lapse cine film which demonstrates the progress of bowing during heating and cooling cycles. An estimate is made of the stress levels in the insulants and the possible effect of these stresses on the reliability of the circuit array is considered. Technological teaching of hybrid microeleetronies (thickfilm). Y. LEROY, M. DESCAMPSand M. VERNET. IERE Conf. Hybrid Microelectronics, Loughborough p. 131. 9-11 Sept. 1975. Principles and fabrication of hybrid circuits (thickfilm) have been taught in the Department Genie Electrique (I.U.T. LILLE) since 1973. The purpose of this paper is to report our experience with this teaching and to give a few details about the devices which were studied and achieved by the students. Thick-film research in a university environment. Prof. D. S. CAMPBELLand P. L. MORAN. IERE Co~f Hybrid Microelectronics. Loughborough p. 135. 9 11 Sept. 1975. This paper is introduced with a brief survey of the background in which we have developed our thick film activities at
m.r. 15/3 ~
187
Loughborough University. As well as outlining the research activities of the department, particularly with regard to our strengths in sonar and digital communications, mention is also made of the type of degree courses which we have, which include the possibility of the third year being spent in industry and a project in the final year (or fourth year) which is linked if at all possible, to the activity in which the student has been involved during his industrial year. Another feature of the department is that we teach Electrical Component Technology as an option for our final year students. Arising from this background, several undergraduate final year projects in thick-film technology are described, including work on laser trimming of resistors and the use of thick films for constructing a delta modulator circuit. The conclusion is reached that thick films are now in a position to offer a very useful facility to electrical and electronic engineering departments where circuits are continually being required for special applications and where the teaching element of the activity can provide a very useful background to students who are interested in component technology.
The hybrid microelectronics explosion in Finland. EERO JARVlNEN. IERE Conf. Hybrid Microelectronics, Loughborough p. 127. 9 11 Sept. 1975. The present paper describes the success with which thick-film hybrid technology has been developed in Finland as a result of close co-operation between the research establishment and industry. In particular it describes the active role of the university in encouraging industry to make use of this technology in its production. A range of automatic finishing machines for thin-film hybrid circuits. GORDON H. YOUNG. IERE Conf. Hybrid Microelectronics, Loughborough p. 241. 9 11 Sept. 1975. The paper deals with a line of machines specifically designed to automate as far as is practical a large in-house requirement for thin-film hybrid circuits used in the telephone industry. Handling innovations are described, and indications are given of production rates and yields. Some problems are discussed, and mention is also made of possible future developments to extend the use of the system. Conduction theory applied to thick-film resistors. ROBERT M. HILL. IERE Conf. Hybrid Microelectronics, Loughborough p. 251.9-11 Sept. 1975. Examination of the specification for a resistor is used to determine the physical requirements and it is shown that these can be met in disordered structures. Comparison of the theoretical characteristics of hopping transport in a narrow band of localised states with the experimentally determined characteristics of a range of thick-film and carbon resistors indicates that the critical features of hopping transport can be observed. Automatic manufacture of custom hybrid microelectronic circuits. ROGER F. RUSSELLand RICHARD THOMPSON. IERE Conf. Hybrid Microelectronics, Loughborough p. 159.9-11 Sept. 1975. The areas of application of hybrid microelectronics have to date been limited in general by economic considerations. Sophisticated electronic systems require considerable design engineering, and conventional hybrid assemblies use labour-intensive techniques. Automation applied to the manufacture of hybrid circuits can significantly improve productivity, and extend the area of application. A technology for high speed computer systems. S. HOLLOCK, D. J. KINNIMENT and N. V. MARTON. IERE Conf. Hybrid Microelectronics, Loughborough p. 143. 9-11 Sept. 1975. This paper describes a technology developed to reduce the