Semiconductor device having high breakdown voltage and low resistance and method of fabricating the same

US5164804A · kind A · utility

Assignee

• Mitsubishi Electric Corporation · JP

Inventor

• Tomohide Terashima · Kasai, JP

Key dates

• Filing date: Aug 19, 1991
• Grant date: Nov 17, 1992
• Expiry date: Aug 19, 2011

Classification

• Technology area (CPC Y): Emerging Cross-Sectional Technologies
• CPC primary: Y10S438/978

Abstract

A P.sup.+ layer (3) and an N.sup.+ layer (1) are provided on the top and bottom surfaces of an N.sup.- layer (21), respectively. An electrode (7) is formed on the P.sup.+ layer (3), while an electrode (8) is formed on the bottom surface of the N.sup.+ layer (1). In a direction from the electrode (7) to the electrode (8), the area of the cross section of the N.sup.- layer (21) is decreased, which cross section is perpendicular to the direction. An N.sup.-- layer (22) is formed complementarily to the N.sup.- layer (21) which is decreased in cross-sectional area. When a potential applied to the electrode (8) is higher than a potential applied to the electrode (7), a depletion layer extends from a PN junction formed by the P.sup.+ layer (3) and the N.sup.- layer (21). Since the impurity concentration of the N.sup.- layer ( 21) is lower than that of the P.sup.+ layer (3), the depletion layer extends substantially to the N.sup.- layer (21). The depletion layer extending to the N.sup.- layer (21) substantially holds the voltage applied across the electrodes (7) and (8). In order to improve a breakdown voltage, the cross-sectional area of the N.sup.- layer (21) is preferably decreased expo…