Method to fabricate the thin film transistor

摘要

Ultrahigh vacuum chemical vapor deposition (UHV/CVD) and chemical mechanical polishing (CMP) systems are used in a method which can fabricate polycrystalline silicon (poly-Si) and polycrystalline silicon-germanium (poly-Si1-x-Gex) thin film transistors at low temperature and low thermal budget. Poly-Si and poly-Si1-x-Gex can be deposited by UHV/CVD without any anneal step. And due to the ultra low base pressure and ultraclean growth environment, the As-deposited poly films have low defect densities. However, the surface morphology retards the usage of the fabricating top-gate poly TFT's. In this invention, the CMP system is used for improving the surface morphology, high performance poly-Si and poly-Si1-x-Gex TFT's can be obtained.