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An approach to computer aided design of multilayer hybrids
World Abstracts on Microelectronics and Reliability
Application of thermodiffusion for the purification of solids. M. J. BUDA. Electron Technol. 12, (1) 65. Presented in this paper are some results of investigations of the migration of impurities in monocrystalline silicon, under the influence of a temperature gradient. To evaluate the changes in level, as well as the impurity concentration profiles, electrical measurements of resistivity, layer radioisotope analysis and analysis on a mass spectrometer were undertaken. Boundary conditions at p--n junctions. E. L. HEASELL. Solid-St. Electron. 22, 853 (1979). In recent correspondence and in earlier papers it has been shown that the use of the quasi-neutrality condition together with the Boltzmann relations at the boundaries of a p--n junction, leads to inconsistencies between the externally applied voltage and the change in potential across the space-charge region. We shall show that such boundary conditions lead to a consistent set of boundary values, when the potentials entering the analysis are correctly interpreted. The difference between the externally applied voltage and the decrease in electrostatic potential across the space-charge region may
763
be interpreted as a ptirely electrostatic phenomenon, associated with the additional majority carriers present in the space charge region to establish quasi-neutrality.
Melt and solution growth of bulk single crystals of quaternary III-V alloys. K. J. BACHMANN, F. A. TmEL and H. SCHREInER, JR. Prog. Crystal Growth Charact. 2, 171 (1979). Due to limitations imposed by phase r~lations and by kinetic parameters, the growth of single crystals of quaternary III-V alloys by melt and solution growth techniques is restricted to a few systems that either have been made or have been theoretically suggested--e.g. G a x l n l - x P r A s a - r Al,Gaflnl_x_ySb--and to certain sections within the existence range of solid solutions in the systems Ga:,lnt_~,AsySbl_y and InPxAsySbt-x-r In f~tvorable regions of composition of the Ga~,In, _~,PyAs,_r system, homogeneous ternary and quaternary crystals have been prepared. For nominally undoped material these alloy crystals exhibit similar net carrier concentrations, defect densities and photo-luminescence properties as bulk single crystals of their binary constituents.
8. THICK- A N D THIN-FILM COMPONENTS, HYBRID CIRCUITS A N D MATERIALS The electroforming of thin films of polypropylene. C. A. HOGARTH and T. IQBAL. Int. J. Electron. 47, (4) 349 (1979). It is shown that on exceeding a threshold applied voltage, thin films of evaporated polypropylene in the form of a sandwich between metal electrodes (aluminium or copper) undergo an electroforming process. There is a resultant augmented current, the development at higher voltages of differential negative resistance, and the samples act as emitters of electrons into a vacuum. The results are consistent with a theory based on the generation of conducting filaments during the forming process. An approach to computer aided design of multilayer hybrids. J. R. SIMS, P. G. CRETER and A. H. LEVEILLE(Part 2), Solid St. Technol. p. 90 (November 1979). In Part I, Oct. 1979, elements of a design approach using an Applicon 2 interactive editing system were detailed. A cell library was described along with other aspects of supporting software. Design methodology and rationale behind design guidelines were discussed. Part II continues with a multilayer example of the CAD approach to illustrate design methodology and guidelines. This specific hybrid also serves to demonstrate the thick film multilayer process and assembly steps with details of materials and techniques. Conductance noise investigations on symmetrical planar resistors with finite contacts. L. K. J. V^NDAMMEand A. H. DE KUIJPER. Solid-St. Electron. 22, 981 (1979). Calculations and experimental results are presented of the voltage fluctuations across a pair of sensor electrodes on a planar resistor. A constant current is passed through another pair of driver electrodes. Three types of geometry are considered which are all invariant for rotations of 90 °. Areas of low and high contribution to the voltage fluctuations are calculated assuming homogeneous conductivity fluctuations. The calculation method rests on the sensitivity theorem in electrical network theory. Calculations are in agreement with experimental results. Electrical properties of anodic aluminium oxide films. F. M. NAZAR and N. AHMAD, lnternat. J. Electron. 47, (1) 81 (1979). The electrical properties of anodic Al2Oa films in the form of AI-AI,Oa-AI structures have been studied. The conduction seems to be a modified Poole-Frenkel process. In some cases a change in the current flow from bulklimited to electrode-limited is observed. The aging effects and the transients observed in these films may be due to
electron trapping in the impurity sites and space charge effects.
A transmission-line analog simulating thin-film distdbutedRC elements. P. BOWRON and' C. TAPINOS. IEEE Trans. Components, Hybrids, and Manufacturing Technology. Chmt-2, (3) 330 (September 1979). Methods of modeling distributed-RC lines by finite-ladder networks are discussed. This culminates in the design and construction of a 20-section adjusta.ble transmission-line analog capable of simulating a variety of uniform and tapered, three-terminal and four-terminal structures. The model also takes into account stray effects and permits performance insight without the otherwise complex irrational-function analysis and numerical evaluation or integrated-circuit fabrication. Its utility is demonstrated with respect to the characteristics of a distributed-lumped notch filter. A range of further applications is suggested. Reliability of clip-on terminals soldered to Ta-Ta2N-NiCrPd-Au thin films. H. N. KELLER. IEEE Trans. Components, Hybrids, and Manufacturing Technology. Chmt-2, (3) 294 (September 1979). Reliability of solder bonds to TaTa2N-NiCr-Pd-Au conductors used for resistor-capacitor (RC) hybrid integrated circuits (HIC's) was investigated. The investigation consisted of aging 60Sn-40 Pb solder bonds at elevated temperatures and measuring the bond strength. The experimental results are similar to those previously measured for Ta2N-Ti-Pd-Au conductors used for resistor HIC's. An Arrhenius extrapolation of the aging data shows that bond life based on acceptable mean bond strength exceeds a 50°C 40-year requirement. The effective activation energy for solder bond aging Ea is slightly greater for Ta-Ta2N-NiCr-Pd-Au (1.4-1.6eV) than for Ta2N-Ti-Pd-Au (l.l-l.3 eV). This difference is attributed to a more continuous RC film, which is produced by the additional tantalum layer, and which consequently has a slower dissolution in solder. Analysis .of weak bond interfaces and metallographic sections indicates that intermetallic compounds cause solder bond aging. However, bond aging EA consistently exceeds activation energies for solid-state diffusion and the formation of the observed intermetallic compounds. The most likely causes for this difference are (l) Pd diffusion into the gold with a consequential reduction in AuSn,, and PdSn,, growth rates, and (2) rate-limiting Sn diffusion to the terminal-film contact area.
Application of thermodiffusion for the purification of solids. M. J. BUDA. Electron Technol. 12, (1) 65. Presented in this paper are some results of investigations of the migration of impurities in monocrystalline silicon, under the influence of a temperature gradient. To evaluate the changes in level, as well as the impurity concentration profiles, electrical measurements of resistivity, layer radioisotope analysis and analysis on a mass spectrometer were undertaken. Boundary conditions at p--n junctions. E. L. HEASELL. Solid-St. Electron. 22, 853 (1979). In recent correspondence and in earlier papers it has been shown that the use of the quasi-neutrality condition together with the Boltzmann relations at the boundaries of a p--n junction, leads to inconsistencies between the externally applied voltage and the change in potential across the space-charge region. We shall show that such boundary conditions lead to a consistent set of boundary values, when the potentials entering the analysis are correctly interpreted. The difference between the externally applied voltage and the decrease in electrostatic potential across the space-charge region may
763
be interpreted as a ptirely electrostatic phenomenon, associated with the additional majority carriers present in the space charge region to establish quasi-neutrality.
Melt and solution growth of bulk single crystals of quaternary III-V alloys. K. J. BACHMANN, F. A. TmEL and H. SCHREInER, JR. Prog. Crystal Growth Charact. 2, 171 (1979). Due to limitations imposed by phase r~lations and by kinetic parameters, the growth of single crystals of quaternary III-V alloys by melt and solution growth techniques is restricted to a few systems that either have been made or have been theoretically suggested--e.g. G a x l n l - x P r A s a - r Al,Gaflnl_x_ySb--and to certain sections within the existence range of solid solutions in the systems Ga:,lnt_~,AsySbl_y and InPxAsySbt-x-r In f~tvorable regions of composition of the Ga~,In, _~,PyAs,_r system, homogeneous ternary and quaternary crystals have been prepared. For nominally undoped material these alloy crystals exhibit similar net carrier concentrations, defect densities and photo-luminescence properties as bulk single crystals of their binary constituents.
8. THICK- A N D THIN-FILM COMPONENTS, HYBRID CIRCUITS A N D MATERIALS The electroforming of thin films of polypropylene. C. A. HOGARTH and T. IQBAL. Int. J. Electron. 47, (4) 349 (1979). It is shown that on exceeding a threshold applied voltage, thin films of evaporated polypropylene in the form of a sandwich between metal electrodes (aluminium or copper) undergo an electroforming process. There is a resultant augmented current, the development at higher voltages of differential negative resistance, and the samples act as emitters of electrons into a vacuum. The results are consistent with a theory based on the generation of conducting filaments during the forming process. An approach to computer aided design of multilayer hybrids. J. R. SIMS, P. G. CRETER and A. H. LEVEILLE(Part 2), Solid St. Technol. p. 90 (November 1979). In Part I, Oct. 1979, elements of a design approach using an Applicon 2 interactive editing system were detailed. A cell library was described along with other aspects of supporting software. Design methodology and rationale behind design guidelines were discussed. Part II continues with a multilayer example of the CAD approach to illustrate design methodology and guidelines. This specific hybrid also serves to demonstrate the thick film multilayer process and assembly steps with details of materials and techniques. Conductance noise investigations on symmetrical planar resistors with finite contacts. L. K. J. V^NDAMMEand A. H. DE KUIJPER. Solid-St. Electron. 22, 981 (1979). Calculations and experimental results are presented of the voltage fluctuations across a pair of sensor electrodes on a planar resistor. A constant current is passed through another pair of driver electrodes. Three types of geometry are considered which are all invariant for rotations of 90 °. Areas of low and high contribution to the voltage fluctuations are calculated assuming homogeneous conductivity fluctuations. The calculation method rests on the sensitivity theorem in electrical network theory. Calculations are in agreement with experimental results. Electrical properties of anodic aluminium oxide films. F. M. NAZAR and N. AHMAD, lnternat. J. Electron. 47, (1) 81 (1979). The electrical properties of anodic Al2Oa films in the form of AI-AI,Oa-AI structures have been studied. The conduction seems to be a modified Poole-Frenkel process. In some cases a change in the current flow from bulklimited to electrode-limited is observed. The aging effects and the transients observed in these films may be due to
electron trapping in the impurity sites and space charge effects.
A transmission-line analog simulating thin-film distdbutedRC elements. P. BOWRON and' C. TAPINOS. IEEE Trans. Components, Hybrids, and Manufacturing Technology. Chmt-2, (3) 330 (September 1979). Methods of modeling distributed-RC lines by finite-ladder networks are discussed. This culminates in the design and construction of a 20-section adjusta.ble transmission-line analog capable of simulating a variety of uniform and tapered, three-terminal and four-terminal structures. The model also takes into account stray effects and permits performance insight without the otherwise complex irrational-function analysis and numerical evaluation or integrated-circuit fabrication. Its utility is demonstrated with respect to the characteristics of a distributed-lumped notch filter. A range of further applications is suggested. Reliability of clip-on terminals soldered to Ta-Ta2N-NiCrPd-Au thin films. H. N. KELLER. IEEE Trans. Components, Hybrids, and Manufacturing Technology. Chmt-2, (3) 294 (September 1979). Reliability of solder bonds to TaTa2N-NiCr-Pd-Au conductors used for resistor-capacitor (RC) hybrid integrated circuits (HIC's) was investigated. The investigation consisted of aging 60Sn-40 Pb solder bonds at elevated temperatures and measuring the bond strength. The experimental results are similar to those previously measured for Ta2N-Ti-Pd-Au conductors used for resistor HIC's. An Arrhenius extrapolation of the aging data shows that bond life based on acceptable mean bond strength exceeds a 50°C 40-year requirement. The effective activation energy for solder bond aging Ea is slightly greater for Ta-Ta2N-NiCr-Pd-Au (1.4-1.6eV) than for Ta2N-Ti-Pd-Au (l.l-l.3 eV). This difference is attributed to a more continuous RC film, which is produced by the additional tantalum layer, and which consequently has a slower dissolution in solder. Analysis .of weak bond interfaces and metallographic sections indicates that intermetallic compounds cause solder bond aging. However, bond aging EA consistently exceeds activation energies for solid-state diffusion and the formation of the observed intermetallic compounds. The most likely causes for this difference are (l) Pd diffusion into the gold with a consequential reduction in AuSn,, and PdSn,, growth rates, and (2) rate-limiting Sn diffusion to the terminal-film contact area.