The grain growth blocking effect of polycrystalline silicon film by thin native silicon oxide barrier during the excimer laser recrystallization

Abstract

A method to control the recrystallization depth of amorphous silicon (a-Si) film during the excimer laser annealing is presented. By irradiating the XeCl excimer laser on the triple film structure of a-Si/thin native silicon oxide (∼20 Å)/thick a-Si layer, only the upper a-Si film is recrystallized, whereas the lower thick a-Si film remains amorphous. The thin native silicon oxide layer blocks the grain growth and prevents the upper grains from growing into the lower a-Si. As a result, the thin oxide film sharply defines the boundary between polycrystalline silicon (poly-Si) and the a-Si layer. The poly-Si/a-Si double layer is useful for the fabrication of high-performance poly-Si thin film transistors.