Patent ID: 6448588
Filing Date: 2002-09-10
Classification: H01L

Abstract:
An insulated gate bipolar transistor comprising:a semiconductor substrate having a high concentration of first conductivity type impurities; a buffer layer formed of an upper buffer layer having a first doping concentration of second conductivity type impurities, which is formed over the semiconductor substrate, and a lower buffer layer having a second doping concentration lower than the first doping concentration, which is formed between the upper buffer layer and the semiconductor substrate; a drift region of a second conductivity type formed on the upper buffer layer; a base region of a first conductivity type formed in a predetermined region of the drift region; an emitter region of a second conductivity type formed in the surface of a predetermined region of the base region; a gate dielectric layer formed on a channel region of the base region; a gate electrode formed on the gate dielectric layer; an emitter electrode formed so as to be electrically connected to the emitter region; and a collector electrode formed so as to be electrically connected to the semiconductor substrate.