Switching element and manufacturing method thereof

Abstract

A switching element is provided having a semiconductor substrate. A trench gate electrode is formed in the upper surface of the semiconductor substrate. An n-type first semiconductor region, a p-type second semiconductor region, and an n-type third semiconductor region are formed in a region in contact with a gate insulating film in the semiconductor substrate. At a position below the second semiconductor region, there is formed a p-type fourth semiconductor region connected to the second semiconductor region and opposing the gate insulating film via the third semiconductor region and containing boron. A high-concentration-carbon containing region having a carbon concentration higher than that of a semiconductor region exposed on the lower surface of the semiconductor substrate is formed in at least a part of the portion of the third semiconductor region, positioned between the fourth semiconductor region and the gate insulating film, that is in contact with the fourth semiconductor region.