Irregularity of film resistivity in a contact interface and contact conductance

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World Abstracts on Microelectronics and Reliability

6. M I C R O E L E C T R O N I C S - - C O M P O N E N T S , SYSTEMS AND EQUIPMENT LCD technology allows panels to move closer to CRT quality. evolutionary direction for silicon integrated circuits. This KoJI TAKAHASHI.J. Electron. Engng., Jpn, 86 (September review highlights the major directions and issues impacting 1989). The B/W technology that allows high-duty multiplex- not only monolithic wafer-scale circuits but also hybrid ing has enabled the manufacture of high-resolution (B/W "wafer-scale" circuits, i.e. mounting pretested chips on STN display with 1024 × 768 dots, and color STN LCD silicon wafer circuit boards. An extensive set of references with (640 x 3) × 400 dots. On the other hand, amorphous is provided to avoid repeating excessively detailed discussilicon technology for TFT display also was established sions available in the cited literature. Instead, a broad and 5-in. CTV and 6.3-in. VDT were developed. Furtheroverview of the objectives and motivations of the considermore, the development of 10-in. VDT is now close to its final able work on wafer-level system components is provided. stage. The perspective emphasized here is that wafer-scale integration provides a foundation on which future systems, Wafer-level system integration: a review. S. K. TEWKSBURY perhaps including advanced simiconductor technologies for and L. A. HORNAK.IEEE Circuits Devices Mag. 22 (Septem- high-performance components, can achieve evolutionary ber 1989). Wafer-scale integration, having endured several increases in performance and decreases in system size similar early and notorious commerical failures, has recently reto those driving advances in today's silicon MOS VLSI ceived increasing attention as an important, longer-term technologies. 7. S E M I C O N D U C T O R

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Subthreshold behaviour of silicon MESFETs on SOS and bulk silicon substrates. U. MAGNUSSON,J. TIREN, H. NORDE and H. BLEICHNER. Solid-St. Electron. 32(11), 931 (1989). The subthreshold characteristics of silicon MESFETs manufactured using both bulk silicon and silicon-on-sapphire (SOS) technology, have been studied, n- and p-type devices have been investigated and their characteristics are presented here. The results show that the subthreshold behaviour for bulk devices is fully comparable with that of MOSFETs, while the SOS devices show a somewhat lower value of subthreshold swing. A comparison between calculated and experimental behaviour is presented which yields information about the influence of the geometry and processing parameters of the subthreshold behaviour. It is proposed that the saturation subthreshold current for bulk transistors can be decreased by a proper design. An improvement for SOS devices, however, requires improved substrate material. Process uniformity and slip dislocation patterns in linearly ramped-temperature transient rapid thermal processing of silicon. MEHRDADM. MOSLEHI. IEEE Trans. Semiconductor Mfg 2(4), 130 (1989). Rapid thermal processing of silicon using transient linearly ramped-temperature saw-toothed and triangular thermal cycles has been evaluated by characterization of the process uniformity and slip dislocation line patterns for a wide range of process parameters. Rapid thermal oxidation was chosen as the process vehicle for these studies. The process uniformity and slip dislocation line patterns are strongly affected by both the transient and steady-state segments of the thermal cycles. The strong dependences of the process uniformity and slip dislocation lines on the thermal cycle parameters suggest that the overall performance of a rapid thermal processing (RTP) reactor must be specified not only under steady-state thermal conditions, but also for controlled transient thermal cycles. The results of this work provide insight and useful methodology for process optimization in order to improve process uniformity, to minimize generation of slip dislocation lines, and also to obtain good device electrical characteristics. Irregularity of film resistivity in a contact interface and contact conductance. MITSUNOBUNAKAMURA.IEEE Trans. Compon. Hybrids mfg Technol. 12(3), 393 (1989). The global behavior of contact phenomena has been studied, using a computer simulation based upon the finite element method and a global model for contact. In this paper, when the film resistivity of a contact interface irregularly fluctuates against the position of the interface, the contact conductances are computed, and the global behavior of contact phenomena is further studied, using the same method and model as in our previous papers. The model of contact consists of two unit conducting cubes and a contact interface between the cubes. The interface is divided into a great number of square

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spots, and the resistivity of each spot is at random determined, but the statistical distribution of the resistivities is assumed to be the normal (Gauss) distribution or error function. It is clarified that the contact conductance does not become low when the standard deviation of the normal distribution is large (i.e. the positional variation of the resistivity is large and spots with high and low resistivity coexist in the same interface) even if the average value of resistivity greatly rises. On the mechanism of sputtering of SiO 2 by Ar at ion energies near the sputtering threshold. S. S. TODOROV and I. R. CFIAKAROV. Vacuum 39(11/12), 1101 (1989). Dynamic Monte Carlo simulation is used to study the influence of the surface binding energy and oxygen redistribution in the target on the sputtering yield of SiO2 bombarded with Ar with energy I00 eV. The experimental data are fitted very well by a model which corresponds to some form of desorption of oxygen from the target surface and diffusion of excess oxygen inside the target from regions of superstoichiometric O content to regions of substoichiometric O content. Carrier transport simulator for silicon based on carrier distribution function evolutions. TAKAHIRO hZUKA and MASAO FUKUMA. Solid-St. Electron. 33(I) 27 (1990). Momentum space electron distributions in bulk silicon were calculated by the direct integration of the Boltzmann transport equation. This approach formulates carrier transitions or "transactions" between discretized states in momentum space, based on physical processes, such as drift and phonon scattering. This method outperforms the Monte Carlo method in determining the distribution functions. This merit enables hot carrier analysis to be implemented with a smaller CPU time. The transient and steady-state distributions are explained by the existence of lucky electrons, energy-dependent scattering rates and the isotropic nature of intervalley scattering. Energy-gap change in silicon n-type inversion layers at low temperature. R. B. M. GIRISCH, R. P. MERTENSand O. B. VERBEKE. Solid-St. Electron. 33(1), 85 (1990). Energy-gap changes in two-dimensional systems at low temperature are treated. The "pure" energy gap Ec-Ev is narrowed by three terms: the majority-carrier exchange energy, and the majority-carrier and minority-carrier correlation energies which are due to dynamic-screening processes. For the first time an expression for the minority-carrier correlation energy in such a two-dimensional system is derived. The expressions for the three bandgap narrowing terms are then applied to silicon n-type inversion layers. The correlation energies appear to be much higher than the corresponding ones in three dimensions. This may be explained by the enhance-