US Patent 9548374 High power insulated gate bipolar transistors

A method of forming a transistor device include forming a drift layer of a first conductivity type, forming a well of a second conductivity type in the drift layer, forming a JFET region with first conductivity type dopant ions in the drift layer, forming a channel adjustment layer of the first conductivity type on the JFET region and the well, implanting first conductivity type dopant ions to form an emitter region of the first conductivity type extending through the channel adjustment layer and into the well, wherein the emitter region is spaced apart from the JFET region by the well, implanting second conductivity type dopant ions to form a connector region of the second conductivity type adjacent the emitter region, forming a gate oxide layer on the channel region, and forming a gate on the gate oxide layer.