Insulated gate bipolar transistor

• Main Authors: Takahashi, Shigeki, Teshima, Takanori, Hirano, Naohiko, Tokura, Norihito
• Format: Patent
• Language: English
• Published: 07.05.2002

This application is based upon Japanese Patent Application No. Hei. 11-288249 filed on Oct. 8, 1999, the contents of which are incorporated herein by reference. Insulated gate bipolar transistors which can restrain causing surge voltage due to an inductance component while an L-load is turned off and can improve a negative characteristic of a sustain voltage during breakdown. An insulated gate bipolar transistor (IGBT) is provided with: a p-type semiconductor substrate; an n-type buffer layer having high impurity concentration; an n-type intermediate layer; and an n-type base layer having low impurity concentration. A p-type well layer and an n-type emitter layer having high impurity concentration are formed in the n-type base layer. The n-type intermediate layer has an intermediate impurity concentration between an impurity concentration of the n-type buffer layer and that of the n-type base layer. Thickness of the intermediate layer is determined so that the depletion layer does not reach the n-type buffer layer even when the switching operation of the L-load is turned off. As a result, it can restrain causing surge voltage and can improve a negative characteristic of a sustain voltage.