FABRICATION OF THIN FILM SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To planarize the surface of a polysilicon thin film by etching the forcibly oxidized part on the surface of polysilicon thereby moderating irregularities on the surface of polysilicon. SOLUTION: An amorphous silicon layer 3 is polycrystallized to form a polysilicon thin film 4 and the surface thereof is oxidized to form an oxide layer 5. The oxide layer 5 is not formed uniformly on the surface of the polysilicon thin film 4 but formed thick at protruding parts and formed thin at recessed parts. The oxide layer 5 is then removed from the surface by etching. The etching rate is set higher for the oxide layer 5 than for the polysilicon thin film 4. Consequently, the oxide layer 5 on the surface of the polysilicon thin film 4 is etched preferentially. Since the protruding parts are subjected to oxidation earlier and etched more than the recessed parts, the polysilicon thin film 4 can be planarized.