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Reticles for wafer imaging systems
World Abstracts continued from page 41
Comparison of enameUed steel substrate properties for thick film use S. J. STEIN, C. H U A N G and S. A. GELB Electrocomp. Sci. Technol. 7, 55 (1980). Porcelain enamelled steels have had a long history of industrial structural and related applications. Recent interest in such materials has centred on electrical uses as a substrate for hybrid circuits, additive printed wiring, and packaging. A study of some of the critical properties of available enamelled steels was undertaken. Five types of enamelled steel substrates from three manufacturers were tested. The electrical properties studied included dielectric constant, dissipation factor, voltage breakdown, surface and bulk insulation resistance. The effect of humidity on the insulation resistance of the enamel coatings themselves was compared. The influence of the thermal conductivity of the substrates was also examined. The properties of a thick film resistor system was determined on the various enamel steel substrates. The properties tested included resistivity and TCR firing sensitivity. The effect of the type of substrate on the properties of a selection of thick film conductors was determined. Conductivity and gold and aluminium wire bond strength were compared on the various substrates. The dielectric properties of a multilayer/crossover dielectric thick film material were compared among 96% alumina, soda-lime glass and the various enamelled steel substrates. Many individual differences between the enamelled steel substrates were found. However, all of the substrates could be utilised to produce satisfactory thick film circuits when the proper choice of thick film materials was made. Continuing changes, improvements and additional sources of supply are expected to overcome some of the present shortcomings. These should enhance the use of such substrates for large area uses and lower cost applications.
2.
P r o d u c t i o n and Processing
Quality assurance of electrical distribution products M. C O U L T E R Electron. Power p.802 (1980). Quality principles have been developed to ensure the technical excellence of the product and the commercial attributes this creates. Effecting these principles in the manufacturing of a particular item requires a wide-ranging effort. Overlay in lithography H. R. ROTYMANN 1BM J. Res. Devel. 24(4), 461 (1980). Advances in lithography rely largely on the capability of reducing overlay errors, which in turn depends on the capability to make twodimensional overlay measurements. This paper describes a simple and accurate method of determining singular overlay errors of step-andrepeat exposure systems with a precision of -+0.011-tin (standard deviation). I/C packaging and interconnection developments M. G. S A G E Circuit Wld. 7(1), 59 (1980). This paper describes the major new I/C packaging technologies now coming into use, i.e. chip carriers and tape automated bonding. It deals with the reasons for their development, where they are most likely to be used and their impact on current interconnection technologies, i.e. PCBs and thick film hybrids. The paper also looks briefly at some new developments in 'off-the-chip' interconnection, e.g. laminates and materials. Influence of manufacturing process on ultrasonic bondability of thick film gold conductors P. C O L L A N D E R , T. LAURINOLLI, E. JARVINEN and M. WEISSENFELT Solid-St. Technol. p.85 (1980). The influence of thick film processing on the ultrasonic (thermosonie) bondability of different types of gold conductors is discussed, and some results of a study of this influence are presented. A new kind of a bondability test, based on observing the yield of good stitch bonds on the conductor being tested, has been used as the tool in defining the bondability. The results of the study show that the most important parameter affecting bondability is the conductor thickness. Due to this fact the hybrid circuit manufacturer can have the most effective control of bondability of conductors by adjusting his screen printing process properly. 42
A new production technique: ion milling D. BOLLINGER and R. FINK Solid-St. Technol. p.79 (1980). A composite overview of one of the more exciting new technologies. Part I presents a comprehensive review of basic principles of ion milling, relating t 9 the design of the equipment and process technology along with their interrelations and trade-offs. Part II, Applications, in our next issue, will represent a review of current and projected future areas of technology. Comparisons including performance and operating advantages of various processes will be included. This article is designed to provide a basic process understanding so that the reader may evaluate its features for use in today's microelectronics programs. Reticles for wafer imaging systems T. GOEDERS Solid-St. Technol. p.91 (1980). Reticles for wafer direct step and repeat optical systems are discussed. The technology of transfer from mask-making to the wafer fabrication line for reticle generation, including format, cleaning and inspection, are outlined in an effort to expand the industry's awareness of existing and established means of working with reticles. A review of these methods and techniques is presented to avoid unwarranted concern about the assimilation of reticle handling into the wafer manufacturing process. Step-and-repeat wafer imaging S. WITI'EKOEK Solid-St. Technol. p.80 (1980). Recent advances in the development of wafer steppers at Philips Research Labs are described. A high resolution, high-throughput, completely automatic step-and-repeat wafer imaging system for VLSI production has been constructed. Emphasis in this paper is on automatic alignment and high resolution imaging. The automatic alignment system is based on relief gratings, and has an accuracy better than -4-0.1 micron. Alignment time is short and the system is compatible with production requirements such as automatic water feeding. The imaging system is a diffraction limited 5× reduction lens with a numerical aperture of 0.3 and a field of 14mm diameter, corrected for ~ ' o wavelengths. Resolution and alignment results on silicon wafers are given. Simultaneous contacting - modern assembly methods of microelectronics P. BARTSCH and B. LAUTERWALD Nachrichtentech. Elektron. 30(7), 292 (1980). (In German.) The continuous reduction of the expenditure for the design and the production of microelectronic circuits requires also highly productive assembly methods. Among the simultaneous contacting methods the film base bond technique takes a first position. Time-parallel contacting, higher heat dissipation and mechanical strength characterise the method. This technique is suited both for the conventional processing to DIP-components and for the direct assembly on wiring bases. Deep UV projection system S. IWAMATSU and K. ASANAMI Solid-St. Technol. p.81 (1980). Fine patterning technology is required for fabrication of LSI devices. Submicron technology, such as electron beam lithography and X-ray lithography, has been extensively studied in laboratories. For I to 2~m design-rule devices, reduction step-and-repeat systems and proximity printing systems have been developed in photolithography. However, throughput and mask damage present problems. These problems can be solved with a mirror projection system using deep ultraviolet light. In this paper, a 1:1 mirror projection system and the experimental results with a new negative resist are described.
Energy saving production of silicon single crystal solar cells by ion implantation and laser annealing E. F. KRIMMEL, A. G. K. LUTSCH, J. S. H. MOOLMAN, H. R U N G E and P. L. SWART Microelectron. J. 11(3), 28 (1980). The energy consumption for a typical solar manufacturing process is discussed. It is shown that by applying laser instead of thermal annealing of the implanted area, 7% of the energy consumption could be saved. Improved solar cells could be obtained by laser annealing.
Comparison of enameUed steel substrate properties for thick film use S. J. STEIN, C. H U A N G and S. A. GELB Electrocomp. Sci. Technol. 7, 55 (1980). Porcelain enamelled steels have had a long history of industrial structural and related applications. Recent interest in such materials has centred on electrical uses as a substrate for hybrid circuits, additive printed wiring, and packaging. A study of some of the critical properties of available enamelled steels was undertaken. Five types of enamelled steel substrates from three manufacturers were tested. The electrical properties studied included dielectric constant, dissipation factor, voltage breakdown, surface and bulk insulation resistance. The effect of humidity on the insulation resistance of the enamel coatings themselves was compared. The influence of the thermal conductivity of the substrates was also examined. The properties of a thick film resistor system was determined on the various enamel steel substrates. The properties tested included resistivity and TCR firing sensitivity. The effect of the type of substrate on the properties of a selection of thick film conductors was determined. Conductivity and gold and aluminium wire bond strength were compared on the various substrates. The dielectric properties of a multilayer/crossover dielectric thick film material were compared among 96% alumina, soda-lime glass and the various enamelled steel substrates. Many individual differences between the enamelled steel substrates were found. However, all of the substrates could be utilised to produce satisfactory thick film circuits when the proper choice of thick film materials was made. Continuing changes, improvements and additional sources of supply are expected to overcome some of the present shortcomings. These should enhance the use of such substrates for large area uses and lower cost applications.
2.
P r o d u c t i o n and Processing
Quality assurance of electrical distribution products M. C O U L T E R Electron. Power p.802 (1980). Quality principles have been developed to ensure the technical excellence of the product and the commercial attributes this creates. Effecting these principles in the manufacturing of a particular item requires a wide-ranging effort. Overlay in lithography H. R. ROTYMANN 1BM J. Res. Devel. 24(4), 461 (1980). Advances in lithography rely largely on the capability of reducing overlay errors, which in turn depends on the capability to make twodimensional overlay measurements. This paper describes a simple and accurate method of determining singular overlay errors of step-andrepeat exposure systems with a precision of -+0.011-tin (standard deviation). I/C packaging and interconnection developments M. G. S A G E Circuit Wld. 7(1), 59 (1980). This paper describes the major new I/C packaging technologies now coming into use, i.e. chip carriers and tape automated bonding. It deals with the reasons for their development, where they are most likely to be used and their impact on current interconnection technologies, i.e. PCBs and thick film hybrids. The paper also looks briefly at some new developments in 'off-the-chip' interconnection, e.g. laminates and materials. Influence of manufacturing process on ultrasonic bondability of thick film gold conductors P. C O L L A N D E R , T. LAURINOLLI, E. JARVINEN and M. WEISSENFELT Solid-St. Technol. p.85 (1980). The influence of thick film processing on the ultrasonic (thermosonie) bondability of different types of gold conductors is discussed, and some results of a study of this influence are presented. A new kind of a bondability test, based on observing the yield of good stitch bonds on the conductor being tested, has been used as the tool in defining the bondability. The results of the study show that the most important parameter affecting bondability is the conductor thickness. Due to this fact the hybrid circuit manufacturer can have the most effective control of bondability of conductors by adjusting his screen printing process properly. 42
A new production technique: ion milling D. BOLLINGER and R. FINK Solid-St. Technol. p.79 (1980). A composite overview of one of the more exciting new technologies. Part I presents a comprehensive review of basic principles of ion milling, relating t 9 the design of the equipment and process technology along with their interrelations and trade-offs. Part II, Applications, in our next issue, will represent a review of current and projected future areas of technology. Comparisons including performance and operating advantages of various processes will be included. This article is designed to provide a basic process understanding so that the reader may evaluate its features for use in today's microelectronics programs. Reticles for wafer imaging systems T. GOEDERS Solid-St. Technol. p.91 (1980). Reticles for wafer direct step and repeat optical systems are discussed. The technology of transfer from mask-making to the wafer fabrication line for reticle generation, including format, cleaning and inspection, are outlined in an effort to expand the industry's awareness of existing and established means of working with reticles. A review of these methods and techniques is presented to avoid unwarranted concern about the assimilation of reticle handling into the wafer manufacturing process. Step-and-repeat wafer imaging S. WITI'EKOEK Solid-St. Technol. p.80 (1980). Recent advances in the development of wafer steppers at Philips Research Labs are described. A high resolution, high-throughput, completely automatic step-and-repeat wafer imaging system for VLSI production has been constructed. Emphasis in this paper is on automatic alignment and high resolution imaging. The automatic alignment system is based on relief gratings, and has an accuracy better than -4-0.1 micron. Alignment time is short and the system is compatible with production requirements such as automatic water feeding. The imaging system is a diffraction limited 5× reduction lens with a numerical aperture of 0.3 and a field of 14mm diameter, corrected for ~ ' o wavelengths. Resolution and alignment results on silicon wafers are given. Simultaneous contacting - modern assembly methods of microelectronics P. BARTSCH and B. LAUTERWALD Nachrichtentech. Elektron. 30(7), 292 (1980). (In German.) The continuous reduction of the expenditure for the design and the production of microelectronic circuits requires also highly productive assembly methods. Among the simultaneous contacting methods the film base bond technique takes a first position. Time-parallel contacting, higher heat dissipation and mechanical strength characterise the method. This technique is suited both for the conventional processing to DIP-components and for the direct assembly on wiring bases. Deep UV projection system S. IWAMATSU and K. ASANAMI Solid-St. Technol. p.81 (1980). Fine patterning technology is required for fabrication of LSI devices. Submicron technology, such as electron beam lithography and X-ray lithography, has been extensively studied in laboratories. For I to 2~m design-rule devices, reduction step-and-repeat systems and proximity printing systems have been developed in photolithography. However, throughput and mask damage present problems. These problems can be solved with a mirror projection system using deep ultraviolet light. In this paper, a 1:1 mirror projection system and the experimental results with a new negative resist are described.
Energy saving production of silicon single crystal solar cells by ion implantation and laser annealing E. F. KRIMMEL, A. G. K. LUTSCH, J. S. H. MOOLMAN, H. R U N G E and P. L. SWART Microelectron. J. 11(3), 28 (1980). The energy consumption for a typical solar manufacturing process is discussed. It is shown that by applying laser instead of thermal annealing of the implanted area, 7% of the energy consumption could be saved. Improved solar cells could be obtained by laser annealing.