Evaluation of Interstitial Si Diffusion Induced by Plasma Etching and Subsequential Annealing for Si Trench Formation using Low Temperature Photoluminescence Spectroscopy

Abstract

Although plasma etching and subsequential annealing process are indispensable to form a uniform trench with a high aspect ratio, the formation of interstitial Si is unavoidable. Understanding the behavior of interstitial Si is an important issue since the point defects diffuse in pairs with dopants. Then, the behavior affects the current drive and threshold voltage of the device. The diffusion rate of interstitial Si has been predicted by existing models [1]. However, detailed behaviors such as diffusion distance and distribution of interstitial Si due to plasma etching and subsequential annealing processes for crystal defects recovery are still unclear. In this study, we evaluated the precise behavior of interstitial Si by using photoluminescence (PL) spectroscopy, which is a powerful method for evaluating point defects.

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