Insulated gate bipolar transistor

• Main Authors: HIRANO NAOHIKO, TOKURA NORIHITO, TAKAHASHI SHIGEKI, TESHIMA TAKANORI
• Format: Patent
• Language: English
• Published: 07.05.2002
• Edition: 7
• Subjects: BASIC ELECTRIC ELEMENTS; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR; ELECTRICITY; SEMICONDUCTOR DEVICES

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.