Techniques capable of improving the yield of IGBTs capable of reducing steady loss, turn-off time, and turn-off loss are provided. Upon formation of openings in an interlayer insulting film formed on a main surface of a substrate, etching of a laminated insulating film of a PSG film and an SOG film and a silicon oxide film is once stopped at a silicon nitride film. Then, the silicon nitride film and the silicon oxide film are sequentially etched to form the openings. As a result, the openings are prevented from penetrating through an n-type source layer and a p+-type emitter layer having a thickness of 20 to 100 nm and reaching the substrate.