| 主权项 |
1. A method for manufacturing a semiconductor device including a trench gate type field effect transistor and a diode which are formed in a semiconductor substrate, the method comprising the steps of:
(a) preparing the semiconductor substrate; (b) after the step (a), forming a first trench and a second trench in the semiconductor substrate; (c) after the step (b), forming a gate electrode of the trench gate type field effect transistor in the first trench through a gate insulating film and forming a dummy gate electrode in the second trench through a dummy gate insulating film; (d) after the step (a), forming a first semiconductor region in the semiconductor substrate, the first semiconductor region of a first conductivity type; and (e) after the step (a), forming a second semiconductor region in the semiconductor substrate, the second semiconductor region having a second conductivity type opposite to the first conductivity type, wherein the second semiconductor region is planarly surrounded by the second trench, wherein a part of the first semiconductor region is located directly below the second semiconductor region and a PN junction is formed between the second semiconductor region and the part of the first semiconductor region located directly below the second semiconductor region, and thereby the diode is formed, and wherein the dummy gate electrode is electrically coupled to one of the first semiconductor region and the second semiconductor region. |
