A method for manufacturing a semiconductor device includes the steps of forming a silicon oxide film on a silicon substrate, and forming a silicon nitride film on the silicon oxide film. The step of forming the silicon nitride film includes the steps of growing a first silicon layer having a thickness larger than a thickness of a monoatomic silicon layer, nitriding the first silicon layer to form a first silicon nitride layer, growing a second silicon layer on the first silicon layer on the first silicon nitride layer, and nitriding the second silicon oxide layer to form a second silicon nitride layer.