RECRYSTALLIZATION METHOD OF POLYSILICON FILM IN THIN FILM TRANSISTOR

摘要

The present invention proposes a crystallization method of the poly-Si thin film in a thin film transistor. A substrate having an insulator layer is provided. An amorphous silicon layer or a micro-crystalline silicon layer having two thickness is first formed on the insulator layer. The region of thinner is defined as the channel region of the TFT, while the region of thicker can be defined as the source/drain regions of the TFT. Next, an excimer laser is used for crystallization. During the excimer laser irradiation, the amorphous silicon layer of thinner is completely melted, and the amorphous silicon layer of thicker is partially melted. The partially melted amorphous silicon layer is used as crystallization seeds. Through formation of the temperature gradient between the completely melted amorphous silicon layer and the partially melted amorphous silicon layer, longitudinal growth of silicon grains in the completely melted region will be performed to grow a poly-Si layer having good homogeneity and large grains.