SEMICONDUCTOR DEVICE OF OVERVOLTAGE SELF-PROTECTION TYPE

摘要

Disclosed is a semiconductor device of overvoltage self-protection type which is safely turned on in response to application of an overvoltage exceeding a breakdown voltage. When, after formation of a predetermined pn junction in a semiconductor substrate, an etched region is formed in a cathode-side base layer from the side of a cathode emitter layer, the breakdown voltage is variable depending on not only the depth but also the diameter of the etched region. Noting the above fact, a circular overvoltage self-protection region having a depth d and a diameter D is provided together with a slot-like turn-on current limiting region having the same depth d but a width smaller than the diameter D of the circular region. The turn-on current limiting region is disposed between the overvoltage self-prevention region and the cathode emitter layer.