| 摘要 |
PROBLEM TO BE SOLVED: To manufacture a reliable semiconductor device comprising a thin-film transistor having stable electrical characteristics.SOLUTION: In a method of manufacturing a semiconductor device comprising a thin-film transistor in which a semiconductor layer comprising a channel formation region is used as an oxide semiconductor film, purity of the oxide semiconductor film is increased. After heating treatment (heating treatment for dehydration or dehydrogenation) for reducing moisture or the like which is an impurity, is performed, slow cooling is performed under an oxygen atmosphere. The impurities, such as the moisture, existing not only in the oxide semiconductor film but also in a gate insulating layer are reduced, and the impurities, such as the moisture, existing on interfaces between the oxide semiconductor film and films which are provided vertically in contact with each other, are reduced. |
