Igbt with a variation of trench oxide thickness regions

Abstract

We describe herein a gate controlled bipolar semiconductor device comprising a collector region of a first conductivity type, a drift region of a second conductivity type located over the collector region, a body region of a first conductivity type located over the drift region, a body region of a second conductivity type located over the drift region, at least one first contact region of a second conductivity type located above the body region and having a higher doping concentration compared to the body region, at least one second contact region of a first conductivity type located laterally adjacent to the at least one first contact region, the at least one second contact region having a higher doping concentration than the body region, at least one active trench extending from a surface into the drift region, wherein the at least one first contact region adjoins at least one active trench so that, in use, a channel region is formed along said at least one active trench and within the body region, and at least two auxiliary trenches extending from the surface into the drift region. The at least two auxiliary trenches each comprise two vertical sidewalls and a bottom surface between the two vertical sidewalls, and an insulation layer along the vertical sidewalls and the bottom surface. The thickness of the insulation layer along the two vertical sidewalls of the at least two auxiliary trenches is less than 1500 Å. The body region of a first conductivity type and the body region of a second conductivity type are both located at least between two adjacent auxiliary trenches.