Integrated gate turn-off device having a vertical power transistor forming a regenerative loop with a lateral transistor

Claim 1

A monolithically integrated gate turn-off semi-conductor switching device comprising: a pair of main terminals for carrying load current; a control terminal which enable said device to be turned On by signal current of one polarity and be turned OFF by a signal current of the opposite polarity; first non-regenerative switch means comprising a power transistor vertically formed in a substrate by first, second and third regions of alternating conductivity types, a diode formed by fourth and fifth regions of opposite conductivity types in series with the aforementioned regions of said vertical transistor but separated therefrom by a sixth region of said substrate doped to provide low minority carrier lifetime therein and prevent vertical regenerative action between said diode and said vertical transistor; said fourth region of said diode being disposed on a bottom surface of said substrate and ohmically connected to one of said main terminals and; said third region of said vertical transistor being disposed on the top surface of said substrate and ohmically connected to the other of said main terminals; second non-regenerative switching means comprising a transistor laterally formed in said substrate by said first region of said vertical transistor, and by a seventh region and an eighth region of alternating conductivity types, said eighth region being disposed on the top surface of said substrate and ohmically connected to said second region of said vertical transistor for delivering base drive current to the latter region when base drive current is applied to the common first region of said first and second switching means, said second non-regenerative switching means being non-conductive in the absence of the last mentioned base drive current; said common first region of said vertical and lateral transistors having a portion disposed on said top surface of said substrate between said eighth region of said lateral transistor and said second region of said vertical transistor of laterally extended dimension to reduce to a negligible level parasitic interaction between said transistors; and said control terminal being connected to said second region of said vertical transistor and said eighth region of said lateral transistor to provide a regenerative coupling between said first and second non-regenerative switching means such that application of said signal current of said one polarity to said control terminal initiates regenerative loop current between said first and second individually non-regenerative switching means to maintain conduction of said first such switching means upon removal of said signal current of said one polarity; said first such switching means upon application of a small signal current of said opposite polarity to said control terminal being turned OFF by interruption of base drive to its said second region.