SEMICONDUCTOR DEVICE MANUFACTURING METHOD AND SEMICONDUCTOR DEVICE

PROBLEM TO BE SOLVED: To provide a semiconductor device which has low on-resistance and enables normally-off.SOLUTION: A semiconductor device manufacturing method comprises: a process of forming an electron transit layer, an electron supply layer, an etching stop layer and a p-type film which are sequentially laminated on a substrate; a process for removing the p-type film in a region except a region where a gate electrode is to be formed by dry etching to form the p-type layer in the region where the gate electrode is to be formed; and a process of forming the gate electrode on the p-type layer. The p-type film is formed from an Al-containing nitride semiconductor material doped by an impurity element to become a p-type. The etching stop layer is formed from GaN-containing material. The dry etching is performed while observing plasma emission in the dry etching and the dry etching is terminated when plasma emission caused by Al is not observed after the dry etching is started.