Patent ID: 7999285

Claim:
An insulated gate bipolar transistor comprising: a first conductive type collector ion implantation area in a substrate; a second conductive type buffer layer on the first conductive type collector ion implantation area, wherein the second conductive type buffer layer comprises a first segment having a first density of second conductive type ions and a second segment having a second density higher than the first density; a drift region in the substrate on the second conductivity type buffer layer; a first conductive type base area in the drift region; a gate on the substrate at a side of the first conductive type base area; a second conductive type emitter ion implantation area in the first conductive base area; an insulating layer on the gate; an emitter electrode electrically connected to the second conductive type emitter ion implantation area; a collector electrode electrically connected to the first conductive type collector ion implantation area; and a lateral insulating layer at a side of the trench, insulating the collector electrode from the second conductive type buffer layer and the drift area, wherein the collector electrode is electrically connected to the first conductive type collector ion implantation area through a trench passing through the drift area and the second conductive type buffer layer of the substrate.