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Capacitors with thin oxide film dielectrics
384
ABSTRACTS ON M I C R O E L E C T R O N I C S
AND R E L I A B I L I T Y
Thick films--how and when to use them. E. LAYER. Electronic Design, April 12, 1965, p. 5S. The thick-film approach uses two basis types of materials--noble metals and ceramics. Thirteen passivecomponent variations can be made from these materials, including resistors, capacitors, thermistors, insulators, crossovers, conductors and various types of pads for interconnection. Some of the elements of a standard circuit, as translated into a thick-film microcircuit, are shown. The circuit has 20 resistors, 4 capacitors, a lead crossover and all necessary conductive paths on one side of an alumina substrate 1' 100 × 0"750 × 0"030 in. Structure and properties of dielectric films. C. WEAVER Vacuum, Vol. 15, No. 4, p. 171. A review is given of existing information on the structure of vacuum-deposited dielectric films as obtained by electron microscopy, electron diffraction and other methods. The occurrence of crazing is discussed and it is shown that it arises from crystallization,, being primarily due to internal stresses within the fihn, although some degree of recrystallizauon generally occurs before crazing is observed. The effect can explain changes in optical properties but does not explain observed changes in dielectric properties. Measurements of the electrical properties of dielectric fiIms show that the losses are generally higher than for bulk material and this may be attributed to ISgh defect concentrations. The ageing, which normally occurs, can generally be attributed to the gradual decrease in the excess vacancy concentration, although adsorbed moisture can cause complicating effects. Results are given for MgF~, NaCI to illustrate these effects. The effects of adsorbed moisture are discussed and it is shown that the Maxwell-Wagner theory is not applicable. The adsorbed moisture usually causes pronounced recrystallization and in earlier work it was thought that this was equivalent to prolonged ageing. There is certainly some degree of overlap but it would now appear that the two processes are separate and distinct. Some of the results obtained for ZnS, SiO and other materials are discussed and attention is drawn to some of the experimental difficulties. The work on stresses in dielectric films is briefly summarized. A few results are given for single-crystal dielectric films prepared by oriented ore rgrowth. Factors influencing the m e a s u r e m e n t of the ionizing efficiency of ion pumps. D. J. TUR~R Vacuum, Vol. 15, No. 4, p. 187. The flow of electric charge in some ion pumps is analysed and deterruination of ionizing efficiency is found to require values for secondary electron emission of various metals for both electron and ion bombardment. These depend on electron energy, ion energy, degree of ionization of the ions and condition of the surfaces. Some of these quantities can be found, while others cannot be determined with any accuracy. Low-pressure sputtered g e r m a n i u m
films. S. P. WOLS~, T. R. PrvvKowsK~ and G. WALLL~S.
3ournal of Vacuum Science and Technology, Vol. 2, No. 3, 3,'Iay/June 1965, p. 97. Germanium films were sputtered on to fused quartz and self-substrates in a low-pressure thermionically supported discharge. Reflection electron diffraction and X-ray examination showed that over comparable temperature ranges the orientation of sputtered germanium films on fused quartz differed from that of evaporated films. Epitaxy was observed on self-substrates at 150°C. Electrical characteristics of evaporated and sputtered films were strikingly similar despite wide variation in substrate material and temperature in deposition rates. Thin film rectifiers. P. LLOYD. British Communicationsand Electronics, Voi. 12, No. 4, June 1965, p. 363. Any thin-film device which possesses rectifying action would be of great interest to circuit designers--rectification effects have been observed in very thin anodic films. The fabrication of experimental thin-film rectifiers by the vacuum deposition and anodization of titanium is described, together with a discussion of their general characteristics and potential application. Precision metal-film resistors. P. L. Kw~¥. British Communicationsand Electronics, VoI. 12, No. 4, June 1965, p. 372. A new process is described for the production of metal film resistors which does not involve the use of vacuum evaporation. A chemical process is involved and it has been adapted for the production of ranges of precision metal film resistors covering the commercial requirements of electrical instruments as well as those of military equipments which call for resistors meeting the stringent RFG7 requirement of DEF 5115. Capacitors with thin oxide film dielectrics. B. WALTON. ElectronicEngineering, June 1965, p. 384. The methods of preparing thin oxide dielectric films are reviewed briefly and it is concluded that the
A B S T R A C T S ON . M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
385
vacuum deposition of refractory metal oxides provides the best results. The process bv which this can be carried out and the production of such capacitors are described in some detaiI. The properties of these capacitors are reviewed and it is shown that they possess manv desirable qualities. E L E C T R O N BEAM T E C H N O L O G Y
Applications of the s c a n n i n g e l e c t r o n m i c r o s c o p e to solid-state devices. [. M. MACKINTOSH. Proc. I.E.E.E., April 1965, p. 370. Applications of the techniques of scanning electron microscopy to solid-state devices are reviewed from the device point of view. An explanation is given of the scanning electron microscope and of the phenomena in this instrument currently judged to be of greatest pertinence to devices. The simultaneous observation of physical topography and voltage contrast is explained, and scanning electron micrographs of actual device structures are presented. Application of this instrument to the polymerization of photoresist films is also discussed, and it is shown that a factor of 5 to 10 improvement in the control of edge sharpness is obtained over images produced by conventional optical techniques. The implications of these techniques to the fabrication of microdevices are discussed in the terms of a relatively simple field-effect device structure. The electron b e a m m i c r o p r o b e as a tool in m a t e r i a l s e n g i n e e r i n g . F. P. LANDIS, R. \V. MERCHANT and P. D. ZE.xtA.x'Y.,IIaterials Research & Standards, Vol. 5, No. 5, May 1965, pp. 219-229. The average chemical composition of a sample of material may not be pertinent when local variations in composition, not amenable to ordinary techniques of chemical analysis, determine the property of interest, such as tensile strength or corrosion resistance. In these cases, the electron microprobe can be used to provide elemental analysis of sample volumes as small as one cubic micron. In this paper, five specific applications of the electron microprobe to chemical analysis are presented: (1) measurement of concentration gradients in metal bonds; (2) analysis of phases in multiphased metallic structures, with special reference to Zircaloy; (3) identification of inclusions present in metals; (4) analysis of corrosion products and surface deposits; and (5) identification and analysis of microscopic particles. Electron beam-oscilloscope photographs illustrating the various analytical modes used with the instrument accompany the discussions.
ABSTRACTS ON M I C R O E L E C T R O N I C S
AND R E L I A B I L I T Y
Thick films--how and when to use them. E. LAYER. Electronic Design, April 12, 1965, p. 5S. The thick-film approach uses two basis types of materials--noble metals and ceramics. Thirteen passivecomponent variations can be made from these materials, including resistors, capacitors, thermistors, insulators, crossovers, conductors and various types of pads for interconnection. Some of the elements of a standard circuit, as translated into a thick-film microcircuit, are shown. The circuit has 20 resistors, 4 capacitors, a lead crossover and all necessary conductive paths on one side of an alumina substrate 1' 100 × 0"750 × 0"030 in. Structure and properties of dielectric films. C. WEAVER Vacuum, Vol. 15, No. 4, p. 171. A review is given of existing information on the structure of vacuum-deposited dielectric films as obtained by electron microscopy, electron diffraction and other methods. The occurrence of crazing is discussed and it is shown that it arises from crystallization,, being primarily due to internal stresses within the fihn, although some degree of recrystallizauon generally occurs before crazing is observed. The effect can explain changes in optical properties but does not explain observed changes in dielectric properties. Measurements of the electrical properties of dielectric fiIms show that the losses are generally higher than for bulk material and this may be attributed to ISgh defect concentrations. The ageing, which normally occurs, can generally be attributed to the gradual decrease in the excess vacancy concentration, although adsorbed moisture can cause complicating effects. Results are given for MgF~, NaCI to illustrate these effects. The effects of adsorbed moisture are discussed and it is shown that the Maxwell-Wagner theory is not applicable. The adsorbed moisture usually causes pronounced recrystallization and in earlier work it was thought that this was equivalent to prolonged ageing. There is certainly some degree of overlap but it would now appear that the two processes are separate and distinct. Some of the results obtained for ZnS, SiO and other materials are discussed and attention is drawn to some of the experimental difficulties. The work on stresses in dielectric films is briefly summarized. A few results are given for single-crystal dielectric films prepared by oriented ore rgrowth. Factors influencing the m e a s u r e m e n t of the ionizing efficiency of ion pumps. D. J. TUR~R Vacuum, Vol. 15, No. 4, p. 187. The flow of electric charge in some ion pumps is analysed and deterruination of ionizing efficiency is found to require values for secondary electron emission of various metals for both electron and ion bombardment. These depend on electron energy, ion energy, degree of ionization of the ions and condition of the surfaces. Some of these quantities can be found, while others cannot be determined with any accuracy. Low-pressure sputtered g e r m a n i u m
films. S. P. WOLS~, T. R. PrvvKowsK~ and G. WALLL~S.
3ournal of Vacuum Science and Technology, Vol. 2, No. 3, 3,'Iay/June 1965, p. 97. Germanium films were sputtered on to fused quartz and self-substrates in a low-pressure thermionically supported discharge. Reflection electron diffraction and X-ray examination showed that over comparable temperature ranges the orientation of sputtered germanium films on fused quartz differed from that of evaporated films. Epitaxy was observed on self-substrates at 150°C. Electrical characteristics of evaporated and sputtered films were strikingly similar despite wide variation in substrate material and temperature in deposition rates. Thin film rectifiers. P. LLOYD. British Communicationsand Electronics, Voi. 12, No. 4, June 1965, p. 363. Any thin-film device which possesses rectifying action would be of great interest to circuit designers--rectification effects have been observed in very thin anodic films. The fabrication of experimental thin-film rectifiers by the vacuum deposition and anodization of titanium is described, together with a discussion of their general characteristics and potential application. Precision metal-film resistors. P. L. Kw~¥. British Communicationsand Electronics, VoI. 12, No. 4, June 1965, p. 372. A new process is described for the production of metal film resistors which does not involve the use of vacuum evaporation. A chemical process is involved and it has been adapted for the production of ranges of precision metal film resistors covering the commercial requirements of electrical instruments as well as those of military equipments which call for resistors meeting the stringent RFG7 requirement of DEF 5115. Capacitors with thin oxide film dielectrics. B. WALTON. ElectronicEngineering, June 1965, p. 384. The methods of preparing thin oxide dielectric films are reviewed briefly and it is concluded that the
A B S T R A C T S ON . M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
385
vacuum deposition of refractory metal oxides provides the best results. The process bv which this can be carried out and the production of such capacitors are described in some detaiI. The properties of these capacitors are reviewed and it is shown that they possess manv desirable qualities. E L E C T R O N BEAM T E C H N O L O G Y
Applications of the s c a n n i n g e l e c t r o n m i c r o s c o p e to solid-state devices. [. M. MACKINTOSH. Proc. I.E.E.E., April 1965, p. 370. Applications of the techniques of scanning electron microscopy to solid-state devices are reviewed from the device point of view. An explanation is given of the scanning electron microscope and of the phenomena in this instrument currently judged to be of greatest pertinence to devices. The simultaneous observation of physical topography and voltage contrast is explained, and scanning electron micrographs of actual device structures are presented. Application of this instrument to the polymerization of photoresist films is also discussed, and it is shown that a factor of 5 to 10 improvement in the control of edge sharpness is obtained over images produced by conventional optical techniques. The implications of these techniques to the fabrication of microdevices are discussed in the terms of a relatively simple field-effect device structure. The electron b e a m m i c r o p r o b e as a tool in m a t e r i a l s e n g i n e e r i n g . F. P. LANDIS, R. \V. MERCHANT and P. D. ZE.xtA.x'Y.,IIaterials Research & Standards, Vol. 5, No. 5, May 1965, pp. 219-229. The average chemical composition of a sample of material may not be pertinent when local variations in composition, not amenable to ordinary techniques of chemical analysis, determine the property of interest, such as tensile strength or corrosion resistance. In these cases, the electron microprobe can be used to provide elemental analysis of sample volumes as small as one cubic micron. In this paper, five specific applications of the electron microprobe to chemical analysis are presented: (1) measurement of concentration gradients in metal bonds; (2) analysis of phases in multiphased metallic structures, with special reference to Zircaloy; (3) identification of inclusions present in metals; (4) analysis of corrosion products and surface deposits; and (5) identification and analysis of microscopic particles. Electron beam-oscilloscope photographs illustrating the various analytical modes used with the instrument accompany the discussions.