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Fabrication of a six-level multilayer structure
and the structural sizes from 1970 to1990 a scientific argument of the parameters and structural dimensions attainable in future for MOS and bipolar components in highest integrated (VLSI) switching circuits is given. Deviations of the electric behaviour of these components from the classical properties are discussed.
1.3
General
IC combines optical sensor, trigger W. R. IVERSEN Electronics, 177 (6 December 1979). Optical detector chip puts a voltage regulator, a Schmitt trigger, a differential amplifier, and a photodiode on the same substrate. Single IC emits multiple signals Electronics, p. 190 (6 December 1979). Frequency synthesizer uses dual-modulus prescaling to replace up to 12 ICs.
2. Memories 5-volt-only, non-volatile RAM owes it all to polysilicon R. KLEIN, W. H. OWEN, R. T. SIMKO and W. E. TCHON Electronics p. 111 (11 October 1979). Electrons tunneling to and from floating gates back up static cells in 1-K n-MOS memory. Bubble memory family extends to megabit size R. P. C A P E C E Electronics, p. 37 (27 September 1979). 2-pm bubble diameters and new planar technology appear in threepart line that ranges from 256 K up.
3.
Microprocessors
Microprocessors: from characterisation to production M. B I L B A U L T Microelectron. J., 10, (3) p. 11 (1979). Microprocessor testing presents more problems than memory testing. Given the regular structure of semiconductor memory, it has been possible to determine a set number of test vectors that will find failures with a high probability of success. Microcomputer can stand alone or join forces with other chips D. W. SMITH Electronics, p. 143 (6 December 1979). Eight operating modes configure powerful 6801 family for controller and microprocessor variations. Microcomputer grants wishes J. G. POSA Electronics, p. 186 (6 December 1979). Single-chip 8-bit unit boasts 32 kilobits of ROM, a 128-byte scratchpad, two 8-byte register banks, and an internal clock generator.
4.
Hybrids
Thin-film devices on silicon chip withstand up to 500°C R O G E R ALLAN Electronics, p. 39 (3 January 1980). Resistors, capacitors fabricated from thin-films can share substrate with MOS devices. Fabrication of a six-level multilayer structure D. J. G E R R Y and R. E. COTE Proc. lnternepcon UK 1979, p. 223, Brighton (16-18 October 1979). The hybrid microelect ronics industry has developed to the point where an increasing number of highly complex circuits are being designed
with thick-flm components. Many complex circuits are sophisticated multilayer structures containing several conductor and dielectric layers. High-yield production of the multilayers requires careful selection of materials and attention to process techniques. This paper describes the fabrication of a six-conductor-level multilayer structure which becomes an analog multiplex circuit for an airborne radar system after resistors, capacitors, and integrated circuits are added. Materials selection is discussed briefly, but major emphasis is placed on the process aspects of the fabrication. A summary of the entire process sequence is followed by detailed discussion of conductor level, via post- and dielectric-level printing. The screens and printing conditions used for each material are discussed with the focus on problems such as the effect on via resolution of size mismatch be~'een dielectric vias and via posts. Process parameters that affect dielectric thickness, via resolution and pinhole frequency are discussed. Cleanliness considerations during fabrication are also covered. Conclusions include recommendations for improvements in process techniques. Heat exchange optimisation technique for high-power hybrid IC's W. MALY and A. P. PIOTROWSKI
IEEE Trans. Components, Hybrids, and Manufacturing Technology, Chmt-2, (2) p. 226 (June 1979). A n algorithm for the optimisation of the heat exchange conditions in high-power thick-film hybrid IC's is presented. The algorithm for the placement of elements which are temperature sensitive and/or heat sources is discussed. The Powell's multivariable unconstrained optimisation technique and the penalty function shifting method in constrained static optimisation are proposed as tools. A practical alr-fireable base metal resistor system E. K. BROWNE Proc. Internepcon, p. 27, Brighton, UK (October 1978). A n improved air-fireable base metal resistor system which is ideally suited to consumer and high volume industrial thick-film applications is discussed. This system provides an attractive alternative to traditional thick-film resistor series, which continue to suffer from the excalating price of precious metals. The novel construction of this material is briefly explained and the special characteristics of practical importance to the thick-film manufacturer are described. A new approach to high volume hermetic hybrid packaging M. SILVERSTEIN and Dr J. E. SERGENT Proc. Intenepcon UK1979, p. 206, Brighton (16-18 October 1979). It was decided to use the substrate as the package bottom for the new process, and that a single piece five sided "dome" cover would complete the package with a hermetic joint. This concept led to a multilayer thick-film process; the input/output (I/O) pads were spaced on 0.625 mm centers and fired onto the ceramic. Other circuitry layers were added as needed, followed by a dielectric layer just inside the substrate periphery but not covering the I/O pads. Finally, platinum gold was fired onto the dielectric to form a solderable seal ring. This type substrate is shown in lower left hand corner of Fig 1; note that several other substrates are also shown having differeot sizes and circuits. The cover to substrate is made by simple solder reftow; it was found necessary to place a small inward dimpled vent hole in the cover top surface to allow pressure equalisation at room temperature. The final seal step was to back fill with clean dry nitrogen and helium gases followed by a wiping action of molten solder across the vent hole for final hermetic seal. Application and reliability of copper plated through hole printed wiring boards F,LASANORI ISOBE, HIDEAKI KOBUNA, KUNIHIKO SUZUKI, TAKAO SATO, and SETUO NOGUCHI NECRes. Dev. Japan, (55) p. 37 (October 1979). Printed Wiring Board (PWB) importance is growing with continual acceleration. Fundamental functions performed on PWB are considered as being mounting and supporting devices as well as to electrically interconnect those devices to obtain required circuitry. Viewed from that fimctional standpoint, PWBs underwent a variety of technological changes, especially in interconneetion density, in accordance with semiconductor devices development. In more detail, a technological requirement for PWB shows an evident tendency toward denser and more reliable interconnection with high accuracy. Besides 37
1.3
General
IC combines optical sensor, trigger W. R. IVERSEN Electronics, 177 (6 December 1979). Optical detector chip puts a voltage regulator, a Schmitt trigger, a differential amplifier, and a photodiode on the same substrate. Single IC emits multiple signals Electronics, p. 190 (6 December 1979). Frequency synthesizer uses dual-modulus prescaling to replace up to 12 ICs.
2. Memories 5-volt-only, non-volatile RAM owes it all to polysilicon R. KLEIN, W. H. OWEN, R. T. SIMKO and W. E. TCHON Electronics p. 111 (11 October 1979). Electrons tunneling to and from floating gates back up static cells in 1-K n-MOS memory. Bubble memory family extends to megabit size R. P. C A P E C E Electronics, p. 37 (27 September 1979). 2-pm bubble diameters and new planar technology appear in threepart line that ranges from 256 K up.
3.
Microprocessors
Microprocessors: from characterisation to production M. B I L B A U L T Microelectron. J., 10, (3) p. 11 (1979). Microprocessor testing presents more problems than memory testing. Given the regular structure of semiconductor memory, it has been possible to determine a set number of test vectors that will find failures with a high probability of success. Microcomputer can stand alone or join forces with other chips D. W. SMITH Electronics, p. 143 (6 December 1979). Eight operating modes configure powerful 6801 family for controller and microprocessor variations. Microcomputer grants wishes J. G. POSA Electronics, p. 186 (6 December 1979). Single-chip 8-bit unit boasts 32 kilobits of ROM, a 128-byte scratchpad, two 8-byte register banks, and an internal clock generator.
4.
Hybrids
Thin-film devices on silicon chip withstand up to 500°C R O G E R ALLAN Electronics, p. 39 (3 January 1980). Resistors, capacitors fabricated from thin-films can share substrate with MOS devices. Fabrication of a six-level multilayer structure D. J. G E R R Y and R. E. COTE Proc. lnternepcon UK 1979, p. 223, Brighton (16-18 October 1979). The hybrid microelect ronics industry has developed to the point where an increasing number of highly complex circuits are being designed
with thick-flm components. Many complex circuits are sophisticated multilayer structures containing several conductor and dielectric layers. High-yield production of the multilayers requires careful selection of materials and attention to process techniques. This paper describes the fabrication of a six-conductor-level multilayer structure which becomes an analog multiplex circuit for an airborne radar system after resistors, capacitors, and integrated circuits are added. Materials selection is discussed briefly, but major emphasis is placed on the process aspects of the fabrication. A summary of the entire process sequence is followed by detailed discussion of conductor level, via post- and dielectric-level printing. The screens and printing conditions used for each material are discussed with the focus on problems such as the effect on via resolution of size mismatch be~'een dielectric vias and via posts. Process parameters that affect dielectric thickness, via resolution and pinhole frequency are discussed. Cleanliness considerations during fabrication are also covered. Conclusions include recommendations for improvements in process techniques. Heat exchange optimisation technique for high-power hybrid IC's W. MALY and A. P. PIOTROWSKI
IEEE Trans. Components, Hybrids, and Manufacturing Technology, Chmt-2, (2) p. 226 (June 1979). A n algorithm for the optimisation of the heat exchange conditions in high-power thick-film hybrid IC's is presented. The algorithm for the placement of elements which are temperature sensitive and/or heat sources is discussed. The Powell's multivariable unconstrained optimisation technique and the penalty function shifting method in constrained static optimisation are proposed as tools. A practical alr-fireable base metal resistor system E. K. BROWNE Proc. Internepcon, p. 27, Brighton, UK (October 1978). A n improved air-fireable base metal resistor system which is ideally suited to consumer and high volume industrial thick-film applications is discussed. This system provides an attractive alternative to traditional thick-film resistor series, which continue to suffer from the excalating price of precious metals. The novel construction of this material is briefly explained and the special characteristics of practical importance to the thick-film manufacturer are described. A new approach to high volume hermetic hybrid packaging M. SILVERSTEIN and Dr J. E. SERGENT Proc. Intenepcon UK1979, p. 206, Brighton (16-18 October 1979). It was decided to use the substrate as the package bottom for the new process, and that a single piece five sided "dome" cover would complete the package with a hermetic joint. This concept led to a multilayer thick-film process; the input/output (I/O) pads were spaced on 0.625 mm centers and fired onto the ceramic. Other circuitry layers were added as needed, followed by a dielectric layer just inside the substrate periphery but not covering the I/O pads. Finally, platinum gold was fired onto the dielectric to form a solderable seal ring. This type substrate is shown in lower left hand corner of Fig 1; note that several other substrates are also shown having differeot sizes and circuits. The cover to substrate is made by simple solder reftow; it was found necessary to place a small inward dimpled vent hole in the cover top surface to allow pressure equalisation at room temperature. The final seal step was to back fill with clean dry nitrogen and helium gases followed by a wiping action of molten solder across the vent hole for final hermetic seal. Application and reliability of copper plated through hole printed wiring boards F,LASANORI ISOBE, HIDEAKI KOBUNA, KUNIHIKO SUZUKI, TAKAO SATO, and SETUO NOGUCHI NECRes. Dev. Japan, (55) p. 37 (October 1979). Printed Wiring Board (PWB) importance is growing with continual acceleration. Fundamental functions performed on PWB are considered as being mounting and supporting devices as well as to electrically interconnect those devices to obtain required circuitry. Viewed from that fimctional standpoint, PWBs underwent a variety of technological changes, especially in interconneetion density, in accordance with semiconductor devices development. In more detail, a technological requirement for PWB shows an evident tendency toward denser and more reliable interconnection with high accuracy. Besides 37