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Data sources for microcomputer component selection
World Abstracts on Microelectronics and Reliability JAWAD AL-MUSAWI. IEEE Trans. Reliab. 37, 75 (1988). Reliability optimization methods for computer-aided design of a Rapid Transit System (RTS) transmission line has been proposed earlier and was useful for simple systems. That method can be applied to a system with small number of sections. There is a combinatorial explosion in the time complexity for the computation of the configuration vector and the solution runs into difficulty very quickly, with increased number of sections. In the present paper, this aspect is addressed so that a more general problem can be solved. The strategy is to divide the system into smaller blocks and find solution sets for the smaller blocks using an efficient search strategy, which are then searched for an overall minimal solution. Often in a problem of decision making of this sort, the trade-off can not be represented by a suitable mathematical model. The n-best solution becomes useful. A sorted list of solutions is prepared with ascending or descending cost, as appropriate. In either case, the best solution heads the list. The strategy is to divide the problem into a number of blocks and for each block, the n-best search strategy is applied to generate sorted list with monotonically increasing or decreasing cost as appropriate. Then a special type of heuristic search strategy, called n-best uniform-cost is used to find the n-best solution of the overall system from the results of the component blocks. The component blocks being small, the issue of combinatorial explosion is reduced by a large measure. The n-best uniform cost search strategy is an extension of the uniform-cost search strategy, well known in the area of artificial intelligence problem solving. The algorithm can be classified as a fuzzy optimization
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technique. An example problem is solved in detail using this algorithm. The results checked with the actual values.
Robust estimators of the 2-parameter gamma distribution. A. ADATIA.IEEE Trans. Reliab. 37, 234 (1988). The available estimators for parameters of the gamma distribution are moment estimators, maximum likelihood estimators, and approximations to the maximum likelihood estimators. These estimators are not suitable for small samples; however they are still being used at the present time. The proposed robust estimators for scale and shape parameters are more suitable for small samples. They have rms-errors that are considerably smaller than those of the other estimators. In addition, they are easier to calculate. Therefore these estimators are appropriate in many applications. Performability evaluation of multicomponent fault-tolerant systems. VINCENZO GRASSI, LORENZO DONATIELLO and GUIDEPPE IAZEOLLA. IEEE Trans. Reliab. 37, 216 (1988). A combined performance and reliability (performability) measure for gracefully degradable fault-tolerant systems is introduced and a closed-form, analytic solution is provided for computing the performability for a class of unrepairable systems which can be modeled by general acyclic Markov processes. This allows the study of models which consider the degradation of more-than-one type of system components (e.g. processors, memories, buses). An efficient evaluation algorithm is provided, with an extensive analysis of its time and space complexity. A numerical example is provided which shows how the combined performance/reliability measure provides for a complete evaluation of the relative merits of different multiprocessor structures.
4. M I C R O E L E C T R O N I C S - - G E N E R A L
Wafer scale integration: a review. P. K. CHATURVEDI. Microelectron. d. 19(2), 4 (1988). The ever-increasing size and complexity of integrated circuit devices seems to lead inevitably to the ultimate "chip", occupying the area of a whole wafer. This concept, which has been studied for many years, carries implications in terms of technology and design which are complex and which require careful consideration if true WSI is to be economically realised. This paper reviews the history of WSI development and describes the current state of the art, together with as-yet unresolved problems. Data sources for microcomputer component selection. PAUL F. PETERSENand R. P. DAVIS. Comput. ind. Engng 14, 381 (1988). The technology related to microcomputers is rapidly changing and has facilitated equally rapid changes in the power and utility of microcomputers. This constantly
changing environment causes major problems when selecting a microcomputer. Does one select the most advanced and sophisticated computer or does one select a computer based solely on current and projected needs? This paper presents methods for determining desired operating characteristics and discusses information sources for determining component compatibility.
Yield implications and scaling laws for submicrometer devices. ALBERTV. FERRIS-PRABHU.IEEE Trans. Semiconductor Mfg 1(2), 49 (1988). As the minimum dimensions of VLSI devices move into the submicrometer range, their sensitivity to smaller defects is expected to increase, with a concomitant decrease in yield. This paper develops yield scaling laws under different assumptions concerning the defect-size probability density function and examines the implications on yield as well as on productivity.
5. M I C R O E L E C T R O N I C S - - D E S I G N
Effects of annealing temperature on electromigration performance of multilayer metailisation systems. HOANO H. HOANG. Proc. IEEE/IRPS, 173 (1988). The electromigration (EM) performance for the Ti:W/AI-I~ Si 2-layer and the Ti/W/AI-I~ Si 3-layer metallizations annealed at elevated temperatures was investigated. The formation of Al12W intermetallic compound, which transforms to Al 5 W as the annealing temperature increases, was observed at the A1alloy/refractory-metal interface. An increase in activation energy and sheet resistance was observed for both the 2-layer and 3-layer systems for annealing above 4500C and 500°C, respectively. The operating lifetimes of the conductors, for 1~o failures, were projected to 80°C and 2 x 105 A/cm 2. The 3-layer system shows a 2X increase in lifetime, relative to the other system, for the standard 30min., 450°C anneal and
AND CONSTRUCTION
an enhancement in film integrity at higher annealing temperatures, near 550°C. However, the 2-1ayer system shows a 2X increase in lifetime near 475°C, due to an increase in activation energy for a lower temperature anneal.
Simulation of focus effects in photolithography. DOUGLAS A. BERNARD. IEEE Trans. Semiconductor Mfg 1(3), 85 (1988). We have considered a simple physical model for bulk imaging effects during latent image formation in a resist layer. The model considers refraction at the air-resist interface, as well as depthwise defocus of the lateral intensity distribution within the resist layer. Our approach represents a first-order correction to the vertical propagation model employed in conventional photolithography simulation, yet preserves the data structures of simulators such as SAMPLE
893
technique. An example problem is solved in detail using this algorithm. The results checked with the actual values.
Robust estimators of the 2-parameter gamma distribution. A. ADATIA.IEEE Trans. Reliab. 37, 234 (1988). The available estimators for parameters of the gamma distribution are moment estimators, maximum likelihood estimators, and approximations to the maximum likelihood estimators. These estimators are not suitable for small samples; however they are still being used at the present time. The proposed robust estimators for scale and shape parameters are more suitable for small samples. They have rms-errors that are considerably smaller than those of the other estimators. In addition, they are easier to calculate. Therefore these estimators are appropriate in many applications. Performability evaluation of multicomponent fault-tolerant systems. VINCENZO GRASSI, LORENZO DONATIELLO and GUIDEPPE IAZEOLLA. IEEE Trans. Reliab. 37, 216 (1988). A combined performance and reliability (performability) measure for gracefully degradable fault-tolerant systems is introduced and a closed-form, analytic solution is provided for computing the performability for a class of unrepairable systems which can be modeled by general acyclic Markov processes. This allows the study of models which consider the degradation of more-than-one type of system components (e.g. processors, memories, buses). An efficient evaluation algorithm is provided, with an extensive analysis of its time and space complexity. A numerical example is provided which shows how the combined performance/reliability measure provides for a complete evaluation of the relative merits of different multiprocessor structures.
4. M I C R O E L E C T R O N I C S - - G E N E R A L
Wafer scale integration: a review. P. K. CHATURVEDI. Microelectron. d. 19(2), 4 (1988). The ever-increasing size and complexity of integrated circuit devices seems to lead inevitably to the ultimate "chip", occupying the area of a whole wafer. This concept, which has been studied for many years, carries implications in terms of technology and design which are complex and which require careful consideration if true WSI is to be economically realised. This paper reviews the history of WSI development and describes the current state of the art, together with as-yet unresolved problems. Data sources for microcomputer component selection. PAUL F. PETERSENand R. P. DAVIS. Comput. ind. Engng 14, 381 (1988). The technology related to microcomputers is rapidly changing and has facilitated equally rapid changes in the power and utility of microcomputers. This constantly
changing environment causes major problems when selecting a microcomputer. Does one select the most advanced and sophisticated computer or does one select a computer based solely on current and projected needs? This paper presents methods for determining desired operating characteristics and discusses information sources for determining component compatibility.
Yield implications and scaling laws for submicrometer devices. ALBERTV. FERRIS-PRABHU.IEEE Trans. Semiconductor Mfg 1(2), 49 (1988). As the minimum dimensions of VLSI devices move into the submicrometer range, their sensitivity to smaller defects is expected to increase, with a concomitant decrease in yield. This paper develops yield scaling laws under different assumptions concerning the defect-size probability density function and examines the implications on yield as well as on productivity.
5. M I C R O E L E C T R O N I C S - - D E S I G N
Effects of annealing temperature on electromigration performance of multilayer metailisation systems. HOANO H. HOANG. Proc. IEEE/IRPS, 173 (1988). The electromigration (EM) performance for the Ti:W/AI-I~ Si 2-layer and the Ti/W/AI-I~ Si 3-layer metallizations annealed at elevated temperatures was investigated. The formation of Al12W intermetallic compound, which transforms to Al 5 W as the annealing temperature increases, was observed at the A1alloy/refractory-metal interface. An increase in activation energy and sheet resistance was observed for both the 2-layer and 3-layer systems for annealing above 4500C and 500°C, respectively. The operating lifetimes of the conductors, for 1~o failures, were projected to 80°C and 2 x 105 A/cm 2. The 3-layer system shows a 2X increase in lifetime, relative to the other system, for the standard 30min., 450°C anneal and
AND CONSTRUCTION
an enhancement in film integrity at higher annealing temperatures, near 550°C. However, the 2-1ayer system shows a 2X increase in lifetime near 475°C, due to an increase in activation energy for a lower temperature anneal.
Simulation of focus effects in photolithography. DOUGLAS A. BERNARD. IEEE Trans. Semiconductor Mfg 1(3), 85 (1988). We have considered a simple physical model for bulk imaging effects during latent image formation in a resist layer. The model considers refraction at the air-resist interface, as well as depthwise defocus of the lateral intensity distribution within the resist layer. Our approach represents a first-order correction to the vertical propagation model employed in conventional photolithography simulation, yet preserves the data structures of simulators such as SAMPLE