Thin Film Transistors Made of Polysilicon Crystallized at 950°C on Steel Substrate

Abstract

ABSTRACTWe fabricated top-gate polycrystalline silicon thin film transistors on steel foil substrates with two processes: (1) Directly deposited n+ source/drain layers. (2) Ion-implanted n+ source/drains. The steel substrates enable reducing the crystallization time of amorphous silicon to polysilicon from 4 hours at 600°C to 20 seconds at 900°C. Thin film transistors were made from polysilicon channel material crystallized at 950°C for either 20 seconds or 20 minutes. The steel foil substrates were passivated with SiO2. The best thin film transistors to date have mobilities of above 30cm2/Vs in both the linear and saturated regions.