SEMICONDUCTOR DEVICE MANUFACTURING METHOD

摘要

PROBLEM TO BE SOLVED: To manufacture and provide a semiconductor device which has a thin film transistor having stable electric characteristics and which has high reliability.SOLUTION: A manufacturing method of a semiconductor device having a thin film transistor which uses an oxide semiconductor film as a semiconductor layer including a channel formation region comprises the steps of: performing a heat treatment (heat treatment for dehydration or dehydrogenation) of increasing purity of the oxide semiconductor film to reduce moisture as an impurity; and reducing an impurity such as moisture which exists not only in the oxide semiconductor film but in a gate insulation layer to reduce an impurity such as moisture which exists in boundary faces among the oxide semiconductor film and films provided on and under and adjacent to the oxide semiconductor film.SELECTED DRAWING: Figure 1