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Active trimming of hybrid integrated circuits
World Abstracts on Microelectronics and Reliability the corresponding higher electron-phonon scattering rate. The transient drift velocities are calculated under the condition of high energy injection. The results for InP show that higher velocities can be obtained over 1000-1500A device lengths for a much larger range of launching energies and applied electric fields than in GaAs. For the case of InAs, due
8. T H I C K - A N D T H I N - F I L M
COMPONENTS,
1105
to the large impact ionization rate, high drift velocities can be obtained since the ionization acts to limit the transfer of electrons to the satellite minima. In the absence of impact ionization, the electrons show the usual runaway effect and transfer readily occurs, thus lowering the drift velocity substantially.
HYBRID CIRCUITS
AND MATERIALS
An experimental approach to vapor phase reflow solder assembly. LARRY R. LICHTENBERG. Solid St. Technol. 183
Electrical characteristics of r.f.-sputtered CdTe thin-films for photovoltaic applications. M. B. DAS, S. V. KRISHNASWAMY,
(February 1984). Shrinking hybrid circuit designs and volume availability are demanding new production techniques. These new designs use all components and processes available to the hybrid designer. High-density and dual-sided circuits are being accepted for production in growing numbers. To meet this challenge, new processes and techniques must be developed. Vapor phase soldering appears to be a process that will lend itself to certain of these applications for solder assembly of components. This paper addresses experiments using vapor phase processing to gather information on assembly yields, component strengths, and design requirements. The results show that there is no significant difference among the soldering processes used in this experiment and that yields are controllable by use of appropriate solder volumes.
RONALOPETKIE, P. SWABand K. VEDAM.Solid-St. Electron. 27 (4), 329 (1984). A method of preparing self-doped p- and n-type and In-doped n-type CdTe thin-films for photovoltaic applications has been developed using r.f. sputtering. Ohmic contacts to n-type films with contact resistivity less than 10-2~--cm 2 have been obtained. Schottky barrier diode test devices, formed by evaporation of various metals including Au on n-CdTe films, have been examined for electrical and photovoltaic evaluation of the sputtered films. Although S.B. diodes based on In doped films, prepared under Cd overpressure, show l~romising electrical and photovoltaic performance (V,,c ~ 315 mV, Isc ~ 4.6 mA/cm2), much improvement remains to be made by further control of dopant concentration and structural details of films.
Analysis of thin film fire sensors. G. ZENTAI and Zs. Multilayer resist processes and alternatives. DONALD W. JOHNSON. Semiconductor Int. 83 (March 1984). Planarized surface topography from multilayering can lead to improved resolution and linewidth control. Here's a description of the various resist processes,
Air and nitrogen-fireable multilayer systems: materials and performance characteristics. Part 1. B. E. TAYLOR, R . R . GETTY, J. HENDERSONand C. R. S. NEEDES.Solid St. Technol. 180 (March 1984). The performance characteristics of precious-metal materials systems used in multilayer interconnect applications are discussed. The processing of these systems is described, and performance characteristics are discussed in detail. Part I addresses in particular the fundamental aspects of printing, viz., rheology, bowing, shorting, and top-layer solderability.
Air and nitrogen-fireable multilayer systems: materials and performance characteristics. Part II. B. E. TAYLOR, R . R . GETTY, J. HENDERSONand C. R. S. NEEDES.Solid St. Technol. 291 (April 1984). Part I of this article appeared in the March issue and dealt with fundamental aspects of printing such as rheology, bowing, shorting, and top layer solderability. In this concluding instalment the performance characteristics of a copper-based nitrogen-fireable materials system used for multilayer interconnect applications are discussed. Data are given on adhesion, solderability, resistivity, and wirebond pull strength.
ILLYEFALVI-VITEZ.Electrocomponent Sci. Technol. 11, 209 (1984). The detection of fire in mines, industrial buildings, ships etc. is an important problem from both the economical and life-protecting aspects. The fire could be detected in several ways, e.g. by the measurement of flame-radiation, heat, pressure, temperature, the aerosols, the gases etc. The Department of Electronic Technology has developed a fire sensor which detects the rate of the increase of temperature. The fire sensor consists of two temperature sensitive resistors with different time-constants. If the increase of temperature in consequence of the fire is fast, the difference between the resistance of the temperature sensors is high, while a slow change in temperature causes only small differences. By connecting the temperature sensitivity sensors into a bridge, the resistance difference can be easily detected. The temperature sensitive resistors are realized by thin film technology using platinum or nickel film on a thin glass or ceramic substrate. Because of the large surface and small volume of the resistor, its time-constant originally is very low but the time-constant could be easily increased by increasing the volume of the resistor. The present paper gives a detailed description of the analysis and the measurement of the temperature sensitive resistors with different time-constants. The technology of the films is also discussed.
Noise investigations on thick film resistors. A. AMBROZYand
G. WOLLITZER. Electrocomponent Sci. Technol. 11, 203 (1984). Compared to metallic thin films or wires thick film resistors have a rather complex structure. Transition metal Metallization of plastics by magnetron sputtering for appli- oxide particles are embedded into a glassy matrix. The cation of membrane switching. A. R. NYAIESH,J. D. WATSON, resistivity depends heavily on the percentage of the conJ. MORGON and C. ELPHICK. Vacuum 34 (5), 527 (1984). A stituents in the composition. It is believed that the main part water cooled magnetron sputtering system has been successof the resistance stems from the touching areas of conductive fully applied to the deposition of silver onto thin thermally grains and that the conduction is by tunneling. fragile Mylar sheets. The sheets were stencil masked to To give a better insight a noise spectrum analysis has been provide a pattern of row and column conductors in a 6,l-cell developed. A DC current is passed through the sample to be membrane switch array which was intended for use in a measured. The output noise voltage is analyzed between microcomputer based aid for the handicapped. The specifi1.6 Hz and 25 kHz using a commercial third-octave analyser. cation for such a microcomputer scanned keyboard matrix is Results are given of an experiment in which the glassy outlined and the design details given for a back-illuminated matrix of thick film resistors was etched away step by step array of cross point switches. Test results indicate that the and the noise was measured vs. the number of etching steps. technique is potentially suitable for the production of lowprofile, high reliability keyboards and other low resistivity Active trimming of hybrid integrated circuits. P. NEMETHand flexible conductor applications. P. KREMER.Electrocomponent Sci. Technol. 11, 231 (1984).
1106
World Abstracts on M icroelectronics and Reliabi hi\
One ot the more important fields of the microelectromc,,, industry is the manufacturing of hybrid integrated circuits. An important part of the manufacturing process is concerned with the trimming of the hybrid integrated circuits. This article deals with the basic principles of active trimming and introduces a microprocessor controlled trimming machine. By comparing aclivc trimming with passive techniques, it can be shown that the active system has some advantages. This article outlines these advantages.
Examination of thick-films using modern surface analytical techniques. G. HARSANYI and G. RIPKA. Electrocomponent Sci. Technol. I!, 219 (1984). Modern surface analytical m e t h o d s / E M P A , AES, SIMS etc. were used for studying the different layers in thick-film integrated circuits. Diffusion and migration effects, surface impurity distributions and surface compositions were examined. Some of the results are presented in this paper. Electrical measurements are not discussed here: only examples of the practical use of the methods are demonstrated. S E M / E D X analyses of some interactions between thick film resistors and dielectrics. GEORGE ADIE, BARBARAHOLODNtK and KEITH PITT. Microelectron. d. 15 (2), 38 {1984). An earlier paper, has described some of the electrical changes which occur when thick film resistors are processed on dielectrics compared with their calibrated behavior on alumina. It was shown that there was some diffusion of constituents between layers. This short paper presents the results of more detailed SEM/EDX analyses carried out on one group of samples from the previous work. Here the resistor material analysed
9. E L E C T R O N ,
ION
Alignment signals for electron beam lithography. YI-CHING LIN and ANDREW R. NEUREUTHER. Solid St. Technol. 117 (February 1984). Monte Carlo (MC) simulations have been used along with experiments to study the alignment signals formed by electrons which are backscattered from silicon topographical marks. A universal curve for the effects of mark depth and beam voltage on signal contrast has been obtained by normalization with respect to the Bethe range, Alignment signals in ternary takeoff angles and quadrantal azimuthal angles are studied. The impact of resist coated over alignment marks on alignment signals is also examined, and the effects of the resist thickness and the profile slope are separated. M a n y signal processing techniques including an energy analysis method for backscattered electrons are evaluated. Based on MC results and resist profiles observed experimentally, a guideline design for alignment marks for use with resist coating is given,
Dielectric breakdown of gate insulator due to reactive ion etching. TOHRU WATANABEand YUKIMASAYOSH1DA.Solid St. Technol. 263 (April 1984). Reactive Ion Etching (RIE) is an essential technology in the VLSI fabrication process. In the RIE system, energetic ions bombard the wafer and may introduce various kinds of damage. Recently, gate breakdown p h e n o m e n a after RIE of gate materials were noticed, The relationship between the gate breakdown phenomenon and various etching conditions is investigated. A breakdown mechanism mode which can reasonably explain the experimental results is proposed.
Tbe growth of high purity GaAs hy molecular beam epitaxy in diffusion pumped systems. G. J. DAVIES and D. A. ANDREWS. Vacuum 34 (5), 543 (1984). Diffusion pumped MBE systems are likely to be technologically important in the development of production semiconductor growth equipment. It is demonstrated, for the first time, that high quality GaAs can be produced in such systems. Both electrical and optical results are presented to illustrate these findings,
was one member only of the Dupont Seric~ i . :he 1000ohms/sq 1730, which is ruthenium dioxide raihct than bismuth ruthenate based. The surfaces onto ~xhkh the resistor was deposited were a 96",, ahlmma, Kyocc~~ A471~ and three Duponl dielectrics, 9950 and 4032, both cclamic filled and 9429 which is a devitrcfymg glass. The m~mhc~ or combinations studied was restricted b5 the lengl?, ~i ',,,*w necessary for carrying out each of the aHai),cs
Scratch-profiles study in thin films using SEM and EI)S. M EL-SHABASY, L. PI)GANY, (i. KO'~(×OS, k. HAJI~ ~md B. SZIKORA.Electroconiponent Sci. "lcchnol. 1 I. 237 I It)84). I hc adhesion of evaporated or sputtered thin lihns to substrates is one of the most important characterising palanlctcr~ in their fabrication. It is a conventional method to ~cratch the films using a stylus and evaluate the shearing stre~,s, which is proportional to the energy of adhesion. For the cvaluation it is necessary to determine the so-called critical load and tile profile of the scratch. The aim during this experimental work wa-, to lind a method to evaluate the scratch profile from the X-ray-line profile and SEM pictures. From SEM pictures, the iateral dimensions and surface morphology of the scratches were studied. The thickness was also studied from X-ray proiilc,,. In this paper the thickness profile measuring method and the conclusion for the scratch method are discussed
Thin-film transistors drive pixels singly. W~:st,t!s R. I\,k:RSfN. Electronics 109 (31 May, 1984!. Liquid-crystal display uses active matrix addressing to achieve higher performance capabilities and iower power consumption.
AND
LASER
BEAMS
Physics of ion beam wafer processing. JULIUS J. MtRAY Semiconductor Int. 130 {April 1984). Future wafer-processing includes greater use of systems based on ion beam physics, beyond today's ion implantation and dry etching. Focused
ion
beam
technology:
reviewing applications
research. MIKE HASSEL SHEARERand GARY COGSWELI. Semiconductor Int. 145 (April 1984). First commercial tbcused ion beam systems can be used for evaluation in semiconductor processing applications.
Automated inspection of wafer patterns with applications in stepping, projection and direct-write lithography. KARL L. HARRIS,PAUL SANDLANDand RUSSELL M. SINGLETON. Solid St. Technol. 159 (February 1984). A newly developed system is described which incorporates several features to tully monitor the ongoing quality of a microlithographic process. This system can be used for either a stepping or scanning photo process or a direct-write by electron beam. The need for such a system for improvements in process cont'ol is briefly reviewed. Several system functions are described including: macro inspection of a patterned wafer at approxlmately I x magnification for large defects, fully automated high speed linear critical dimension measurements and area critical dimension measurement, measurement of pattern to pattern registration error, and automated inspection fo~ patterning and random or repeating defects. Some application examples and estimated throughputs are presented.
A current conduction mechanism in laser recrystallized silicon metal-oxide-semiconductor transistors. HAN-StrE~
8. T H I C K - A N D T H I N - F I L M
COMPONENTS,
1105
to the large impact ionization rate, high drift velocities can be obtained since the ionization acts to limit the transfer of electrons to the satellite minima. In the absence of impact ionization, the electrons show the usual runaway effect and transfer readily occurs, thus lowering the drift velocity substantially.
HYBRID CIRCUITS
AND MATERIALS
An experimental approach to vapor phase reflow solder assembly. LARRY R. LICHTENBERG. Solid St. Technol. 183
Electrical characteristics of r.f.-sputtered CdTe thin-films for photovoltaic applications. M. B. DAS, S. V. KRISHNASWAMY,
(February 1984). Shrinking hybrid circuit designs and volume availability are demanding new production techniques. These new designs use all components and processes available to the hybrid designer. High-density and dual-sided circuits are being accepted for production in growing numbers. To meet this challenge, new processes and techniques must be developed. Vapor phase soldering appears to be a process that will lend itself to certain of these applications for solder assembly of components. This paper addresses experiments using vapor phase processing to gather information on assembly yields, component strengths, and design requirements. The results show that there is no significant difference among the soldering processes used in this experiment and that yields are controllable by use of appropriate solder volumes.
RONALOPETKIE, P. SWABand K. VEDAM.Solid-St. Electron. 27 (4), 329 (1984). A method of preparing self-doped p- and n-type and In-doped n-type CdTe thin-films for photovoltaic applications has been developed using r.f. sputtering. Ohmic contacts to n-type films with contact resistivity less than 10-2~--cm 2 have been obtained. Schottky barrier diode test devices, formed by evaporation of various metals including Au on n-CdTe films, have been examined for electrical and photovoltaic evaluation of the sputtered films. Although S.B. diodes based on In doped films, prepared under Cd overpressure, show l~romising electrical and photovoltaic performance (V,,c ~ 315 mV, Isc ~ 4.6 mA/cm2), much improvement remains to be made by further control of dopant concentration and structural details of films.
Analysis of thin film fire sensors. G. ZENTAI and Zs. Multilayer resist processes and alternatives. DONALD W. JOHNSON. Semiconductor Int. 83 (March 1984). Planarized surface topography from multilayering can lead to improved resolution and linewidth control. Here's a description of the various resist processes,
Air and nitrogen-fireable multilayer systems: materials and performance characteristics. Part 1. B. E. TAYLOR, R . R . GETTY, J. HENDERSONand C. R. S. NEEDES.Solid St. Technol. 180 (March 1984). The performance characteristics of precious-metal materials systems used in multilayer interconnect applications are discussed. The processing of these systems is described, and performance characteristics are discussed in detail. Part I addresses in particular the fundamental aspects of printing, viz., rheology, bowing, shorting, and top-layer solderability.
Air and nitrogen-fireable multilayer systems: materials and performance characteristics. Part II. B. E. TAYLOR, R . R . GETTY, J. HENDERSONand C. R. S. NEEDES.Solid St. Technol. 291 (April 1984). Part I of this article appeared in the March issue and dealt with fundamental aspects of printing such as rheology, bowing, shorting, and top layer solderability. In this concluding instalment the performance characteristics of a copper-based nitrogen-fireable materials system used for multilayer interconnect applications are discussed. Data are given on adhesion, solderability, resistivity, and wirebond pull strength.
ILLYEFALVI-VITEZ.Electrocomponent Sci. Technol. 11, 209 (1984). The detection of fire in mines, industrial buildings, ships etc. is an important problem from both the economical and life-protecting aspects. The fire could be detected in several ways, e.g. by the measurement of flame-radiation, heat, pressure, temperature, the aerosols, the gases etc. The Department of Electronic Technology has developed a fire sensor which detects the rate of the increase of temperature. The fire sensor consists of two temperature sensitive resistors with different time-constants. If the increase of temperature in consequence of the fire is fast, the difference between the resistance of the temperature sensors is high, while a slow change in temperature causes only small differences. By connecting the temperature sensitivity sensors into a bridge, the resistance difference can be easily detected. The temperature sensitive resistors are realized by thin film technology using platinum or nickel film on a thin glass or ceramic substrate. Because of the large surface and small volume of the resistor, its time-constant originally is very low but the time-constant could be easily increased by increasing the volume of the resistor. The present paper gives a detailed description of the analysis and the measurement of the temperature sensitive resistors with different time-constants. The technology of the films is also discussed.
Noise investigations on thick film resistors. A. AMBROZYand
G. WOLLITZER. Electrocomponent Sci. Technol. 11, 203 (1984). Compared to metallic thin films or wires thick film resistors have a rather complex structure. Transition metal Metallization of plastics by magnetron sputtering for appli- oxide particles are embedded into a glassy matrix. The cation of membrane switching. A. R. NYAIESH,J. D. WATSON, resistivity depends heavily on the percentage of the conJ. MORGON and C. ELPHICK. Vacuum 34 (5), 527 (1984). A stituents in the composition. It is believed that the main part water cooled magnetron sputtering system has been successof the resistance stems from the touching areas of conductive fully applied to the deposition of silver onto thin thermally grains and that the conduction is by tunneling. fragile Mylar sheets. The sheets were stencil masked to To give a better insight a noise spectrum analysis has been provide a pattern of row and column conductors in a 6,l-cell developed. A DC current is passed through the sample to be membrane switch array which was intended for use in a measured. The output noise voltage is analyzed between microcomputer based aid for the handicapped. The specifi1.6 Hz and 25 kHz using a commercial third-octave analyser. cation for such a microcomputer scanned keyboard matrix is Results are given of an experiment in which the glassy outlined and the design details given for a back-illuminated matrix of thick film resistors was etched away step by step array of cross point switches. Test results indicate that the and the noise was measured vs. the number of etching steps. technique is potentially suitable for the production of lowprofile, high reliability keyboards and other low resistivity Active trimming of hybrid integrated circuits. P. NEMETHand flexible conductor applications. P. KREMER.Electrocomponent Sci. Technol. 11, 231 (1984).
1106
World Abstracts on M icroelectronics and Reliabi hi\
One ot the more important fields of the microelectromc,,, industry is the manufacturing of hybrid integrated circuits. An important part of the manufacturing process is concerned with the trimming of the hybrid integrated circuits. This article deals with the basic principles of active trimming and introduces a microprocessor controlled trimming machine. By comparing aclivc trimming with passive techniques, it can be shown that the active system has some advantages. This article outlines these advantages.
Examination of thick-films using modern surface analytical techniques. G. HARSANYI and G. RIPKA. Electrocomponent Sci. Technol. I!, 219 (1984). Modern surface analytical m e t h o d s / E M P A , AES, SIMS etc. were used for studying the different layers in thick-film integrated circuits. Diffusion and migration effects, surface impurity distributions and surface compositions were examined. Some of the results are presented in this paper. Electrical measurements are not discussed here: only examples of the practical use of the methods are demonstrated. S E M / E D X analyses of some interactions between thick film resistors and dielectrics. GEORGE ADIE, BARBARAHOLODNtK and KEITH PITT. Microelectron. d. 15 (2), 38 {1984). An earlier paper, has described some of the electrical changes which occur when thick film resistors are processed on dielectrics compared with their calibrated behavior on alumina. It was shown that there was some diffusion of constituents between layers. This short paper presents the results of more detailed SEM/EDX analyses carried out on one group of samples from the previous work. Here the resistor material analysed
9. E L E C T R O N ,
ION
Alignment signals for electron beam lithography. YI-CHING LIN and ANDREW R. NEUREUTHER. Solid St. Technol. 117 (February 1984). Monte Carlo (MC) simulations have been used along with experiments to study the alignment signals formed by electrons which are backscattered from silicon topographical marks. A universal curve for the effects of mark depth and beam voltage on signal contrast has been obtained by normalization with respect to the Bethe range, Alignment signals in ternary takeoff angles and quadrantal azimuthal angles are studied. The impact of resist coated over alignment marks on alignment signals is also examined, and the effects of the resist thickness and the profile slope are separated. M a n y signal processing techniques including an energy analysis method for backscattered electrons are evaluated. Based on MC results and resist profiles observed experimentally, a guideline design for alignment marks for use with resist coating is given,
Dielectric breakdown of gate insulator due to reactive ion etching. TOHRU WATANABEand YUKIMASAYOSH1DA.Solid St. Technol. 263 (April 1984). Reactive Ion Etching (RIE) is an essential technology in the VLSI fabrication process. In the RIE system, energetic ions bombard the wafer and may introduce various kinds of damage. Recently, gate breakdown p h e n o m e n a after RIE of gate materials were noticed, The relationship between the gate breakdown phenomenon and various etching conditions is investigated. A breakdown mechanism mode which can reasonably explain the experimental results is proposed.
Tbe growth of high purity GaAs hy molecular beam epitaxy in diffusion pumped systems. G. J. DAVIES and D. A. ANDREWS. Vacuum 34 (5), 543 (1984). Diffusion pumped MBE systems are likely to be technologically important in the development of production semiconductor growth equipment. It is demonstrated, for the first time, that high quality GaAs can be produced in such systems. Both electrical and optical results are presented to illustrate these findings,
was one member only of the Dupont Seric~ i . :he 1000ohms/sq 1730, which is ruthenium dioxide raihct than bismuth ruthenate based. The surfaces onto ~xhkh the resistor was deposited were a 96",, ahlmma, Kyocc~~ A471~ and three Duponl dielectrics, 9950 and 4032, both cclamic filled and 9429 which is a devitrcfymg glass. The m~mhc~ or combinations studied was restricted b5 the lengl?, ~i ',,,*w necessary for carrying out each of the aHai),cs
Scratch-profiles study in thin films using SEM and EI)S. M EL-SHABASY, L. PI)GANY, (i. KO'~(×OS, k. HAJI~ ~md B. SZIKORA.Electroconiponent Sci. "lcchnol. 1 I. 237 I It)84). I hc adhesion of evaporated or sputtered thin lihns to substrates is one of the most important characterising palanlctcr~ in their fabrication. It is a conventional method to ~cratch the films using a stylus and evaluate the shearing stre~,s, which is proportional to the energy of adhesion. For the cvaluation it is necessary to determine the so-called critical load and tile profile of the scratch. The aim during this experimental work wa-, to lind a method to evaluate the scratch profile from the X-ray-line profile and SEM pictures. From SEM pictures, the iateral dimensions and surface morphology of the scratches were studied. The thickness was also studied from X-ray proiilc,,. In this paper the thickness profile measuring method and the conclusion for the scratch method are discussed
Thin-film transistors drive pixels singly. W~:st,t!s R. I\,k:RSfN. Electronics 109 (31 May, 1984!. Liquid-crystal display uses active matrix addressing to achieve higher performance capabilities and iower power consumption.
AND
LASER
BEAMS
Physics of ion beam wafer processing. JULIUS J. MtRAY Semiconductor Int. 130 {April 1984). Future wafer-processing includes greater use of systems based on ion beam physics, beyond today's ion implantation and dry etching. Focused
ion
beam
technology:
reviewing applications
research. MIKE HASSEL SHEARERand GARY COGSWELI. Semiconductor Int. 145 (April 1984). First commercial tbcused ion beam systems can be used for evaluation in semiconductor processing applications.
Automated inspection of wafer patterns with applications in stepping, projection and direct-write lithography. KARL L. HARRIS,PAUL SANDLANDand RUSSELL M. SINGLETON. Solid St. Technol. 159 (February 1984). A newly developed system is described which incorporates several features to tully monitor the ongoing quality of a microlithographic process. This system can be used for either a stepping or scanning photo process or a direct-write by electron beam. The need for such a system for improvements in process cont'ol is briefly reviewed. Several system functions are described including: macro inspection of a patterned wafer at approxlmately I x magnification for large defects, fully automated high speed linear critical dimension measurements and area critical dimension measurement, measurement of pattern to pattern registration error, and automated inspection fo~ patterning and random or repeating defects. Some application examples and estimated throughputs are presented.
A current conduction mechanism in laser recrystallized silicon metal-oxide-semiconductor transistors. HAN-StrE~