METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a thin film transistor in which deterioration at initial operation is not likely to be caused, and to provide a method for manufacturing the thin film transistor.SOLUTION: A thin film transistor includes: a gate insulating layer at least whose uppermost surface is a silicon nitride layer; a semiconductor layer over the gate insulating layer; and a buffer layer over the semiconductor layer, where concentration of nitrogen in the vicinity of an interface between the semiconductor layer and the gate insulating layer in the semiconductor layer is lower than that of the buffer layer and other parts of the semiconductor layer. Such a thin film transistor can be manufactured by exposing the gate insulating layer to an air atmosphere and performing plasma treatment on the gate insulating layer before the semiconductor layer is formed.