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The migration of semiconductor processes to singlewafer vacuum cluster tools has rendered configuration an important decision variable in fab operation and heightened the impact of reliability on fab performance. We address these closely linked issues by deriving the optimal configuration and operation of systems of cluster tools in the presence of scheduled maintenance.The two extremes in the spectrum of possible configurations are the serial configuration, in which the modules in a tool are all different, each representing a step in a process sequence, and the parallel configuration, in which each tool is assigned only one process step. We predict that the latter can offer higher throughputs. However, this advantage may be slight when equipment downtime is relatively schedulable and infrequent, in which the case the serial configuration may be preferable because of its superior cycle times. We also derive optimal lot sizing and release policies for systems of cluster tools. We conclude that fabs will gradually migrate from parallel configurations to serial as cluster tools become more reliable and cycle time becomes more important.Index Terms-Flexible manufacturing systems, manufacturing planning, manufacturing scheduling, performance models, semiconductor cluster tools, semiconductor device manufacture.

To develop really new products, a company often needs to get a handle on really new technologies. Although some breakthrough products simply combine existing technologies in novel ways, other innovations require the successful commercialization of nascent technologies. In other words, such innovations depend on entirely new structures and methods that have been demonstrated in a research environment but have not yet been refined to the point where they are ready for production. The path from nascent technology to full‐scale production presents numerous managerial challenges that must be overcome if a company is to develop really new products that involve really new technologies. Samuel Wood and Gary Brown discuss these challenges, and they describe methods for managing the successful commercialization of nascent technologies. They illustrate these methods by examining Sony's commercialization of laser diodes—semiconductor devices that play an important role in the operation of CD players and other optical disk readers. They divide the process of commercializing nascent technology into three stages: appropriation, implementation, and manufacture. The first stage—appropriation—involves monitoring, assessing, and capturing new technologies. Sony handles this stage with a small, loosely structured research organization, separate from the development organization. In this stage, management must ensure that the objectives pursued by the research organization support the development organization's long‐term goals. To foster coordination between research and development, Sony employs such network‐building techniques as internal research symposia and technology expositions, orientation periods for researchers, transferring managers between research and development, and transferring researchers to development and other functions. The implementation stage involves transferring knowledge to development, as well as refining the technology to the point where it is reproducible, testable, and documented. Sony facilitates technology commercialization by transferring project team members from research to development and making those people responsible for implementation. To reach the final stage, manufacture, the firm must find the means for developing and refining mass production tools and procedures. Meeting this challenge requires close interaction and integration between process and production engineers.

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Visions of future wafer fabs include the use of integrated single-wafer processors to achieve fast cycle times and contain rising production costs. A survey of IC manufacturers, equipment vendors, and IC manufacturing literature was used to generate hypothetical conventional and alternative fabs to evaluate the effect of integrated single-wafer processing on cycle time and cost performance. The distinguishing features of the alternative fab are 1) all thermal processes performed on singlewafer processors; 2) back-end wet cleans performed on singlewafer processors; 3) integration of single-wafer processors into clusters or cells wherever practical, and 4) extensive use of insitu insitu insitu process monitors to replace in-line process monitors. Modeling and simulation of the resulting fabs suggest that integrated singlewafer processing can reduce the cycle time of conventional fabs by about 50% without having a significant effect on wafer production cost. Tool integration and single-wafer processing must be used together to achieve these performance improvements. Although traditional lot sizes appeared to be appropriate for both fabs, improvements in cluster tool reliability and process step similarity could change optimal integrated tool configurations and reduce optimal lot sizes in the future.