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The diffusion of tin and selenium in gallium arsenide
312
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
T h e o r y of the space-charge-limited surface-ch~n~nel dielectric triode. G. T. 3,VRIGHT,Soh'dState Electron., Vol. 7, 1964, pp. 167-175. The operating mechanisms of a surface-channel solid-state triode working under space-charge-limited conditions are described. Theoretical current-voltage characteristics are evaluated and anticipated to be similar to those of the vacuum pentode. The concepts of perveance and amplification factor provide a simple and accurate description of triode parameters. Temperature insensitive and low noise operation is anticipated. Numerical estimates indicate that drain currents of several tens of milliamperes are achievable with gain-bandwidth products of several hundred Mc/s.
Interconnection of integrated circuit fiat packs in Autonetics improved Minuteman programme. E. F. HARMON, IEEE Trans., Vol. CP-11, June 1964, No. 2. (Proc. Electronic Components Conf., Washington, May 1964, p. 135.) Design studies for the Improved Minuteman computer reveal the necessity for advanced microcircuit interconnection techniques in order to capture the potential advantages of integrated circuits. The development of a unique multilayer board concept is described in terms of such factors as design procedures; masking techniques; and fabrication, test and re-work methods. With reliability as the dominant factor in all trade-off studies the significance of physical and electrical parameters is discussed as well as the influence of considerations of producibility, yield and system constraints.
SEMICONDUCTOR INTEGRATED CIRCUITS N e w t e r n a r y semiconducting compounds, Cd4(P, As)2-(CI, Br, 1) a. L. St;CHOW and N. R. STEMPL~,.7. Electrochem. Soc., 110, July 1963, pp. 766-769. Five new ternary semiconducting compounds have been synthesized: Cd4P~CI.~, Cd4P,Bra, Cd4P~I 3, Cd4As~Brs and Cd4As,.I s. These compounds are all cubic (space group Pa3) and isomorphous with each other. Their lattice constants vary with sizes of the component atoms. The structure appears to be based on a nearly face-centered cubic arrangement of cadmium atoms in a pseudocell having half the edge of the true primitive cell. All the new compounds are deeply coloured. Estimates of their energy band gaps have been made from optical and electrical measurements. A tunable solid-circuit filter suitable for a n i.f. amplifier. T. E. PRICE, G. BRADSHAWand C. H. TAYLOR, Electron. Engng., December 1963, p. 806. The distributed capacitance associated with a diffused silicon resistor can be utilized to form an RC network having frequency selective characteristics. This article describes the general theory, design, fabrication and results obtained for such a device. As an example of its use, details are given of a single stage 20 Mc/s i.f. amplifier.
*Mechanical and electrical properties of thermoeompression bonds. M. C. McKINt~'oN and R. F. HOEC~:ELMAN,IEEE Int. Con. Record (USA), Vol. 11, Pt. 6, 1963, pp. 93-103. Contacts between microscopic projections at the surface form the real contact area. The thermocompression process employs elevated temperatures and pressures to induce plasticity in order to increase the real contact area. A thermocompression bond creates such intimate contact between the two materials that strong Van der Waal's and chemical bonding forces come into play causing the materials to adhere. A comparison of resistivity measurement techniques on epitaxial silicon. E. E. GARDNER,J. F. HALLENBACK,Jr., and P. A. SCHUMA~rN,Jr., Solid-State Electron., 6, June 1963, pp. 311-313. A brief description of two new nondestructive methods of measuring epitaxial layer resistivity is given. These two methods are then compared with an existing method and with each other. The precision obtained with these techniques when measuring N on N + epitaxial silicon is given. The diffusion of tin and selenium in gallium arsenide. R. W. FANE and A. J. Goss, Solid-State Electron., Vol. 6, 1963, pp. 383-387. Radioactive tracer measurements of the diffusion of selenium and tin in gallium arsenide have been compared with observations ofp-n junctions by staining and thermalprobe techniques. Junction depths are consistently less than the penetration depths indicated by radio-
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
313
active profiles. In addition, the profiles do not fit solutions of Fick's Law. The possible mechanism of diffusion is discussed, assuming "slow" and "fast" components to exist, of which only the "slow" component is observed electrically. Mesoplasmas and "second b r e a k d o w n " in sUlcon junctions. A. C. E.~CLtSH, Solid-State Electron., Vol. 6, 1963, pp. 511-521. Mesoplasrna breakdown in silicon p-n junctions is analysed on the basis of a stable microscopic molten sphere of semiconductor controlling the electrical properties of the breakdown region. The size of the melt ranges from a radius of a few ~ upwards for a power input above 1 W. An explanation of transistor "second breakdown" is given. The preparation of very flat surfaces of silicon by electro-polishing. D. BAKERand J. R. TILLMAN, Soh'd-State Electron., Vol. 6, 1963, pp. 589-596. Slices of silicon can be very successfully polished by anodic dissolution in a cell using a horizontal rotating disk as cathode, a viscous electrolyte, and a very small anode-cathode spacing (e.g. 150 I~). The surfaces of n-type material of resistivity >0.05 Gcm must be illuminated during polishing, necessitating perforation of the disk to admit a beam of light to them. The optimum cell voltage is always above that for which the differential conductance of the cell is negative, and is usually about 10 V. The dissolution of 50 ~ from a surface initially lapped or mechanically polished leaves it very flat and free of all work damage; electron micrographs show the residual local departures from flatness to be < 0.01 tL. Material so prepared offers advantages in planar technology and as substrates for epitaxial growth. A full quantitative understanding of the mechanisms involved is still lacking however.
Molecular blocks simplify microcircuits. V. Uzuh'OGLUand M. H. WroTE, Electronics, February 14, 1964, p. 36. Although integrated circuits are beginning to be accepted widely, it has been pointed out that making use of some properties of semiconductor devices to realize some of the required functions of a microcircuit may prove more advantageous than transferring each element of a circuit to an integrated block. This paper deals with this approach and shows how to use double-base diodes, tunnel diodes and oxide-coated devices to perform useful functions in microcircuits. Equivalent circuit p a r a m e t e r s for functional electronic blocks. G. F. PITMAN, Jr., Int. Electron., March 1964-, p. 32. The design of functional electronic blocks, especially for efficient quantity production, is a technology in itself. Successful functional block design requires an interplay between persons skilled in systems, circuits and block design. By taking into account in preliminary circuit design work the equivalent electrical circuit properties of functional blocks and a few general principles of block design, much can be done toward efficient creation of an effective design. Research at ILR.E.mNo. 7. Fabrication techniques for a diffused planar p n p transistor. G. B~DSH^W and C. H. TAYLOR. Brit. Comm. Electron., April 1964-, pp. 24-8-251. The six main processes necessary to fabricate planar pnp silicon transistors from single-crystal silicon slices of the required resistivity and quality are described in this article. They are, in general, common to the fabrication of any planar silicon device or integrated circuit, and are as follows: (1) slice preparation, (2) oxide growth, (3) photolithography, (4-) diffusion, (5) evaporation and micro-alloying of contact areas and (6) dice and lead bonding.
Interface states in abrupt s e m i c o n d u c t o r heterojunctions. W. G. OLDH&Mand A. G. MIL~S, Solid-State Electron., Vol. 7, 1964, pp. 153-165. A perfect match of lattice constants is not normally possible in heterojunctions, and therefore defects, mainly in the form of interfacial dislocations, are present at the heterojunction interface. Experimental evidence for the electrical properties of isolated bulk dislocations, grain boundary dislocations and dangling bonds at surfaces, as well as at SiO2-Si interfaces, suggests that interracial defects at heterojunctions produce important effects. In particular, for lattice mismatches of about 1 per cent or greater, sufficient interface states should be created to bend the bands at the interface and thus largely determine the device characteristics. In addition, interfacial dislocations would be expected to cause severe minority carrier recombination, even for lattice mismatches of as low as 0-05 per cent. Therefore, efficient wide-gap-emitter action in Ge/GaAs p-n heterojunctions is likely to be difficult to achieve. The electrical characteristics of some n-n and p-p
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
T h e o r y of the space-charge-limited surface-ch~n~nel dielectric triode. G. T. 3,VRIGHT,Soh'dState Electron., Vol. 7, 1964, pp. 167-175. The operating mechanisms of a surface-channel solid-state triode working under space-charge-limited conditions are described. Theoretical current-voltage characteristics are evaluated and anticipated to be similar to those of the vacuum pentode. The concepts of perveance and amplification factor provide a simple and accurate description of triode parameters. Temperature insensitive and low noise operation is anticipated. Numerical estimates indicate that drain currents of several tens of milliamperes are achievable with gain-bandwidth products of several hundred Mc/s.
Interconnection of integrated circuit fiat packs in Autonetics improved Minuteman programme. E. F. HARMON, IEEE Trans., Vol. CP-11, June 1964, No. 2. (Proc. Electronic Components Conf., Washington, May 1964, p. 135.) Design studies for the Improved Minuteman computer reveal the necessity for advanced microcircuit interconnection techniques in order to capture the potential advantages of integrated circuits. The development of a unique multilayer board concept is described in terms of such factors as design procedures; masking techniques; and fabrication, test and re-work methods. With reliability as the dominant factor in all trade-off studies the significance of physical and electrical parameters is discussed as well as the influence of considerations of producibility, yield and system constraints.
SEMICONDUCTOR INTEGRATED CIRCUITS N e w t e r n a r y semiconducting compounds, Cd4(P, As)2-(CI, Br, 1) a. L. St;CHOW and N. R. STEMPL~,.7. Electrochem. Soc., 110, July 1963, pp. 766-769. Five new ternary semiconducting compounds have been synthesized: Cd4P~CI.~, Cd4P,Bra, Cd4P~I 3, Cd4As~Brs and Cd4As,.I s. These compounds are all cubic (space group Pa3) and isomorphous with each other. Their lattice constants vary with sizes of the component atoms. The structure appears to be based on a nearly face-centered cubic arrangement of cadmium atoms in a pseudocell having half the edge of the true primitive cell. All the new compounds are deeply coloured. Estimates of their energy band gaps have been made from optical and electrical measurements. A tunable solid-circuit filter suitable for a n i.f. amplifier. T. E. PRICE, G. BRADSHAWand C. H. TAYLOR, Electron. Engng., December 1963, p. 806. The distributed capacitance associated with a diffused silicon resistor can be utilized to form an RC network having frequency selective characteristics. This article describes the general theory, design, fabrication and results obtained for such a device. As an example of its use, details are given of a single stage 20 Mc/s i.f. amplifier.
*Mechanical and electrical properties of thermoeompression bonds. M. C. McKINt~'oN and R. F. HOEC~:ELMAN,IEEE Int. Con. Record (USA), Vol. 11, Pt. 6, 1963, pp. 93-103. Contacts between microscopic projections at the surface form the real contact area. The thermocompression process employs elevated temperatures and pressures to induce plasticity in order to increase the real contact area. A thermocompression bond creates such intimate contact between the two materials that strong Van der Waal's and chemical bonding forces come into play causing the materials to adhere. A comparison of resistivity measurement techniques on epitaxial silicon. E. E. GARDNER,J. F. HALLENBACK,Jr., and P. A. SCHUMA~rN,Jr., Solid-State Electron., 6, June 1963, pp. 311-313. A brief description of two new nondestructive methods of measuring epitaxial layer resistivity is given. These two methods are then compared with an existing method and with each other. The precision obtained with these techniques when measuring N on N + epitaxial silicon is given. The diffusion of tin and selenium in gallium arsenide. R. W. FANE and A. J. Goss, Solid-State Electron., Vol. 6, 1963, pp. 383-387. Radioactive tracer measurements of the diffusion of selenium and tin in gallium arsenide have been compared with observations ofp-n junctions by staining and thermalprobe techniques. Junction depths are consistently less than the penetration depths indicated by radio-
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
313
active profiles. In addition, the profiles do not fit solutions of Fick's Law. The possible mechanism of diffusion is discussed, assuming "slow" and "fast" components to exist, of which only the "slow" component is observed electrically. Mesoplasmas and "second b r e a k d o w n " in sUlcon junctions. A. C. E.~CLtSH, Solid-State Electron., Vol. 6, 1963, pp. 511-521. Mesoplasrna breakdown in silicon p-n junctions is analysed on the basis of a stable microscopic molten sphere of semiconductor controlling the electrical properties of the breakdown region. The size of the melt ranges from a radius of a few ~ upwards for a power input above 1 W. An explanation of transistor "second breakdown" is given. The preparation of very flat surfaces of silicon by electro-polishing. D. BAKERand J. R. TILLMAN, Soh'd-State Electron., Vol. 6, 1963, pp. 589-596. Slices of silicon can be very successfully polished by anodic dissolution in a cell using a horizontal rotating disk as cathode, a viscous electrolyte, and a very small anode-cathode spacing (e.g. 150 I~). The surfaces of n-type material of resistivity >0.05 Gcm must be illuminated during polishing, necessitating perforation of the disk to admit a beam of light to them. The optimum cell voltage is always above that for which the differential conductance of the cell is negative, and is usually about 10 V. The dissolution of 50 ~ from a surface initially lapped or mechanically polished leaves it very flat and free of all work damage; electron micrographs show the residual local departures from flatness to be < 0.01 tL. Material so prepared offers advantages in planar technology and as substrates for epitaxial growth. A full quantitative understanding of the mechanisms involved is still lacking however.
Molecular blocks simplify microcircuits. V. Uzuh'OGLUand M. H. WroTE, Electronics, February 14, 1964, p. 36. Although integrated circuits are beginning to be accepted widely, it has been pointed out that making use of some properties of semiconductor devices to realize some of the required functions of a microcircuit may prove more advantageous than transferring each element of a circuit to an integrated block. This paper deals with this approach and shows how to use double-base diodes, tunnel diodes and oxide-coated devices to perform useful functions in microcircuits. Equivalent circuit p a r a m e t e r s for functional electronic blocks. G. F. PITMAN, Jr., Int. Electron., March 1964-, p. 32. The design of functional electronic blocks, especially for efficient quantity production, is a technology in itself. Successful functional block design requires an interplay between persons skilled in systems, circuits and block design. By taking into account in preliminary circuit design work the equivalent electrical circuit properties of functional blocks and a few general principles of block design, much can be done toward efficient creation of an effective design. Research at ILR.E.mNo. 7. Fabrication techniques for a diffused planar p n p transistor. G. B~DSH^W and C. H. TAYLOR. Brit. Comm. Electron., April 1964-, pp. 24-8-251. The six main processes necessary to fabricate planar pnp silicon transistors from single-crystal silicon slices of the required resistivity and quality are described in this article. They are, in general, common to the fabrication of any planar silicon device or integrated circuit, and are as follows: (1) slice preparation, (2) oxide growth, (3) photolithography, (4-) diffusion, (5) evaporation and micro-alloying of contact areas and (6) dice and lead bonding.
Interface states in abrupt s e m i c o n d u c t o r heterojunctions. W. G. OLDH&Mand A. G. MIL~S, Solid-State Electron., Vol. 7, 1964, pp. 153-165. A perfect match of lattice constants is not normally possible in heterojunctions, and therefore defects, mainly in the form of interfacial dislocations, are present at the heterojunction interface. Experimental evidence for the electrical properties of isolated bulk dislocations, grain boundary dislocations and dangling bonds at surfaces, as well as at SiO2-Si interfaces, suggests that interracial defects at heterojunctions produce important effects. In particular, for lattice mismatches of about 1 per cent or greater, sufficient interface states should be created to bend the bands at the interface and thus largely determine the device characteristics. In addition, interfacial dislocations would be expected to cause severe minority carrier recombination, even for lattice mismatches of as low as 0-05 per cent. Therefore, efficient wide-gap-emitter action in Ge/GaAs p-n heterojunctions is likely to be difficult to achieve. The electrical characteristics of some n-n and p-p