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Defect control in silicon crystal growth and wafer processing

Accurate control of the defectivity of silicon crystals and wafers is a subject of immense importance to both the silicon and IC industries. Exploding costs of wafer development and production as well as the processing of 300mm wafers means that predictive defect engineering is now, more than ever a requirement for both industries. There is little scope any more for iterative approaches to these problems. It is simply too expensive. Where ever possible generic – as opposed to application specific or tailored wafer products suitable for a wide variety of demanding applications must be developed in order meet cost targets. This paper reviews recent developments in the understanding several aspects of defect control in silicon crystal growth and wafer processing which are of particular relevance to 300mm silicon products and processes. Among the subjects covered are the problems of intrinsic point defect concentration and reaction control in the growth crystals including effects of impurities and the uses of vacancy concentration profiles installed into silicon wafer in order to achieve ideal oxygen precipitation performance. The importance of accurate modeling of defect dynamics is stressed. Finally, the requirement of dealing with significantly higher levels of mechanical stress in 300 mm processing has led to a new appreciation of the role played by oxygen in the locking of dislocations and the dynamics of wafer hardening during processing. These developments are reviewed briefly.