METHOD FOR FABRICATING THIN FILM TRANSISTOR

摘要

PURPOSE: A method for fabricating a thin film transistor is provided to improve the characteristics of the device by increasing breakdown voltage and by reducing leakage current of the thin film transistor using an insulation film of an ONO(Oxide-Nitride-Oxide) structure instead of an oxide as a gate insulation film. CONSTITUTION: A polysilicon film(2) for a gate electrode is formed on an interlayer insulation film, and the first oxide(5) and a nitride film(6) and the second oxide are formed on the interlayer insulation film(1) as a gate insulation film. And a polysilicon film(4) for a channel is formed on the second oxide. The polysilicon film for a gate electrode is a heavily doped polysilicon thin film. A source gas of a silicon is a SiH4 or Si2H6, and the silicon is deposited at a temperature of 450-800 deg.C and at a pressure of 0.1-1 torr as thick as 10-1000 angstrom. After patterning the polysilicon thin film, the oxide layer(5) is generated on the gate electrode by etching the patterned polysilicon thin film with a NH4OH solution containing HF and H2O2. Then, the nitride film is deposited as thick as 30-400 angstrom.