Patent ID: 7977165

Claim:
A method of manufacturing a semiconductor device, comprising the steps of: (a) forming a semiconductor element (IGBT) and interconnect on a first surface of a semiconductor substrate of a first conductivity type; (b) covering the semiconductor element and interconnect with a protective film, and attaching a reinforcing plate over the protective film; (c) after the step (b), forming a first semiconductor region of the first conductivity type by implanting first impurity ions on a second surface of the semiconductor substrate which is opposite to the first surface of the semiconductor substrate; (d) after the step (b), forming a second semiconductor region of a second conductivity type opposite to the first conductivity type by implanting second impurity ions on the second surface of the semiconductor substrate; and (e) after the steps (c) and (d), peeling off the reinforcing plate from the first surface of the semiconductor substrate, wherein the second semiconductor region is formed on the first semiconductor region at the second surface of the semiconductor substrate.