Silicon epitaxial growth on poly-Si film by HWCVD for low-temperature poly-Si TFTs

Abstract

A two-step process consisting of the preparation of poly-Si seed film by vapor-induced crystallization and the growth of an epitaxial Si layer on the poly-Si seed film via hot-wire chemical vapor deposition (HWCVD ) is introduced to obtain a high-quality poly-Si film at a temperature below 500 degrees C. The epitaxial Si by HWCVD was successfully grown on the poly-Si seed film at 450 degrees C, and the crystallinity of the poly-Si seed film was maintained up to the surface of the epitaxial Si. With the two-step process, it was observed that the grain size was enlarged twofold compared to that of the poly-Si seed film. It was also found that the grain-boundary defect density was reduced. Moreover, the concentration of Ni and Al, which were introduced for the crystallization of a-Si, was lower at the surface. (c) 2007 The Electrochemical Society.