Yield learning and the sources of profitability in semiconductor manufacturing and process development

A numerical model that identifies the high-leverage variables associated with profitability in semiconductor manufacturing is presented. Varying the parameters of the model demonstrates that a rapid yield-learning rate determines profitability more than any other factor does. Factors such as ramping-up early, adding fab capacity, depressing the terminal fault density, and shrinking die size all yield diminishing returns. The model also suggests that developing a rapid problem-solving capability in the early stages of process development enables successful yield learning.     

Validation and verification of expert systems

Validation and verification (V&V) are procedures used to evaluate system structure or behavior with respect to a set of requirements. Although expert systems are often developed as a series of prototypes without requirements, it is not possible to perform V&V on any system for which requirements have not been prepared. In addition, there are special problems associated with the evaluation of expert systems that do not arise in the evaluation of conventional systems, such as verification of the completeness and accuracy of the knowledge base. The criticality of most National Aeronautics and Space Administration (NASA) missions makes it important to be able to certify the performance of the expert systems used to support these missions. This paper presents recommendations for the most appropriate methods for integrating V&V into the Expert System Development Methodology (ESDM) and suggestions for the most suitable approaches for each stage of ESDM development.     

Increasing semiconductor manufacturing's strategic value to a firm

Manufacturing firms in many North American industries are struggling with whether to continue to produce major components for their systems or end-products. In some instances, the suppliers of these very components are also dealing with whether to produce them or merely design them. Large end-product firms and some semiconductor merchants, for example, are calling into question the internal fabrication of chips. This paper examines what can be done to increase the strategic value of an internal chip facility. It discusses six specific activities many of which focus on better satisfying the needs of a fabricator's internal or external customers. By taking the initiative in implementing these activities fabrication management will have identified a seventh way to add value. The recommendations made here also have general implications for firms that produce major components other than semiconductors, and for companies supplied with these components by strategic partners     

Review of expert systems technology

An overview of expert systems technology is provided from a development point of view. The intent is to provide assistance in the practical aspects of constructing expert systems. Emphasis is placed on the benefits and limitations of expert systems, the various phases of the development processes, and the software tools used to expedite the development. Special attention is given to the interface with engineering management     

Application of expert systems to systems reliability evaluation

An expert system for diagnosing rough ride problems in heavy trucks has been developed and can be used on a personal computer. The system operates on two levels of knowledge data base: shallow — acquired from truck service personnel and causal obtained from a multiprobe vibration analysis system (MVAS) through a preprocessing neural network. The justification for selecting neural networks is presented as are virtues and drawbacks of the developed system.     

Successful initiation of expert systems projects

The author suggests project management concepts and techniques that can facilitate a successful initiation of new expert systems projects. The principle of communication, cooperation, and coordination is emphasized. The standard responsibility chart is presented as a mechanism for coordinating the efforts of the project personnel. The roles of domain experts, knowledge engineers, and programmers are discussed in the context of initiating and managing an expert systems projects. Specific recommendations to the practitioners for getting started are presented. The guidelines can be easily adapted for a customized procedure for any specific project situation     

提高测量系统的生产力

基于计算机的测量和自动化应用中结合了高速的以太网提高了生产力     

Reduction of semiconductor laser amplifier induced distortion andcrosstalk for WDM systems using light injection

Semiconductor laser amplifiers cause both distortion and crosstalk in WDM systems due to gain saturation. A method using light injection is experimentally demonstrated to reduce distortion and crosstalk. In a two-channel experiment with a data rate of 2.5 Gbit/s, it is found that light injection can eliminate the BER floor due to distortion and crosstalk     

Waveform distortion due to near-end reflections in direct detectionlightwave systems using single-mode semiconductor lasers

Deterministic rate equations describing the nonlinear modulation dynamics of single-mode semiconductor lasers are used to assess the performance implications of external optical feedback for multigigabit-per-second lightwave systems. The rapid increase in the eye closure penalty resulting in a return loss of about 20 dB, is consistent with published experimental data     

优化反射率以增强半导体激光器输出功率

在考虑了俄歇效应的情况下，用行波速率方程组研究了半导体激光器的输出功率与端面反射率的关系。给出了在不同偏置电流下使激光器输出端输出功率最大所需要的端面反射率。利用主动监控法在１．３μｍＩｎＧａＡｓＰ半导体激光器端面上完成了这种功率增强膜的镀制，在所选择的６０ｍＡ工作电流处，镀膜后激光器的输出功率增加了１３０％。     

Optimized cooling systems for high-power semiconductor devices

Straightforward air cooling of semiconductor devices has gradually been replaced by methods using liquid coolants, especially water cooling. In this paper, more advanced cooling devices for hockey-puck-type and module-type semiconductors are suggested. An established heat sink made of aluminum nitride for the water cooling of hockey-puck-type semiconductors has been used as a basis for the development of high-performance heat sinks for increased heat flux densities. By means of thermal and fluid dynamics simulation tools the internal geometry has been optimized with regard to improved heat transfer and reduced pressure drop. The simulation results have been confirmed by a number of experiments using various measuring techniques. As an alternative cooling method for semiconductor modules, a modified baseplate comprising a number of fins for direct water cooling has been suggested. For an intelligent temperature management control algorithms have been developed, resulting in a prototype application-specific integrated circuit which has been implemented for test purposes     

Reliability of semiconductor devices for submarine-cable systems

The Bell System initiated development of semiconductor devices for use in broad-band repeatered coaxial submarine-cable telephone systems in the early 1960's. Development of such devices has continued at varying levels of activity to this date. Now, over a decade later, more than five years of successful operational life have elapsed on the first installed system; one transatlantic system is in operation and several more of equal or greater length are in various stages of construction. Laboratory-like life validation tests have been conducted on all the devices for use in these systems, and up to seven years of history have elapsed on groups of 100 devices representative of the five varieties used in the first system. No failures have been observed either in service or in life validation tests, thereby confirming a FIT rate of better than five. Moreover, variables data for the representative samples aged for seven years indicate that the confirmed FIT rate may be extremely conservative. Silicon diodes aged below breakdown are more stable than the life-test system designed to evaluate their reliability. Silicon diodes aged in breakdown show a linear drift in leakage current which is so small that it is not detectable except with an ultrasensitive test system. Germanium transistors evaluated over this same period show that the change in current gain they exhibit will be substantially less than the goal established for them at the inception of development. Silicon transistors being developed for a new higher capacity system show promise of exceeding the stability of the more extensively evaluated germanium devices. These results have broader implications than their relevance to submarine-cable system performance since they indicate that the reliability which has long been considered to be inherent in semiconductor devices not only has been demonstrably achieved in quantitative terms but can be considered to be designable for future system applications.     

Rule-based expert systems for network management and operations: anintroduction

The functions that can be performed by an integrated communication network management expert system are identified. Expert systems are defined, and knowledge representation, knowledge acquisition, and inference engines are discussed. A sample application problem using OPS5 is presented     

A reliability model for real-time rule-based expert systems

This paper uses two modeling tools to analyze the reliability of real-time expert systems: (1) a stochastic Petri net (SPN) for computing the conditional response time distribution given that a fixed number of expert system match-select-act cycles are executed, and (2) a simulation search tree for computing the distribution of expert system match-select-act cycles for formulating a control strategy in response to external events. By modeling the intrinsic match-select-act cycle of expert systems and associating rewards rates with markings of the SPN, the response time distribution for the expert system to reach a decision can be computed as a function of design parameters, thereby facilitating the assessment of reliability of expert systems in the presence of real-time constraints. The utility of the reliability model is illustrated with an expert system characterized by a set of design conditions under a real-time constraint. This reliability model allows the system designers to: (1) experiment with a range of selected parameter values; and (2) observe their effects on system reliability     

Power system voltage control by distributed expert systems

A case study of the application of a distributed control scheme to a power system control is presented. In addition, an investigation has been conducted into voltage control. Combined injection of VAr-compensating devices controlled by distributed expert systems has been proposed as a measure to maintain voltage stability in a power system under heavy loading conditions. A simulation study has been carried out by using five workstations that represent a power system and four VAr-compensating devices. The results demonstrate the effectiveness of the proposed system for voltage recovery     

Designing expert systems for real-time diagnosis of self-correctingnetworks

The authors discuss design issues that they have encountered during an investigation of expert systems for network management that they believe to be generic to the real-time diagnosis of self-correcting networks. By real-time they mean that the diagnostic system must keep pace with a dynamic process, that is, the flow of alarms from intelligent network elements. The objective is to present the operator with a set of recommended actions rather than large volumes of raw alarm data. They outline the general requirements of such a system and then suggest how each can be addressed using an expert-system approach