Thyristor with turn-off capability having an improved emitter region, and processes for the fabrication thereof

摘要

A thyristor comprises, in a semiconductor material wafer (106), a number of N+-type main emitter elements (142, 142'), generally parallel to one another, and, doped more weakly, N-type channel emitter elements (128) oriented transversely to the main emitter elements. The N+-type emitter elements can be formed without a critical alignment step, as they need only be oriented transversely to a number of gate electrode fingers (108, 108') in the upper part of the wafer. The N-type channel emitter elements are preferably brought into coincidence with the gate electrode fingers in such a way that narrow elongated regions are enclosed which make it possible to provide more N-type channel emitter elements for a thyristor of a given size. This increases the number of turn-off channels in both sides of the channel regions, as a result of which the level of the current which the thyristor can turn off by suitable biasing of the gate electrode fingers is increased. A P-type base region comprising a layer of increased conductivity relative to the upper surface of the P-type base region further increases the level of the appliance current which can be turned off by the thyristor. Processes for fabricating a thyristor having the abovementioned features comprise a process for forming the N+-type main emitter elements without a critical alignment step, a process for forming the narrow, elongated N-type channel emitter elements, brought into coincidence with the gate electrode fingers, and a process for forming the P-type base region comprising a layer of increased ... Original abstract incomplete. IMAGE