Controlled rectifier having ring gate with internal protrusion for dV/dt control

Claim 1

A controlled rectifier having a ring gate and an increased resistance to dV/dt turn-on; said controlled rectifier comprising a wafer of monocrystalline semiconductor material having generally flat parallel first and second surfaces; said first surface containing a central emitter diffusion region having a generally flat cathode contact secured thereto; said emitter region being of one of the conductivity types; said emitter region being formed in and surrounded at said first surface by a second region which is of the other of the conductivity types; said emitter region having a short peripheral portion extending from its outer periphery; and a ring-shaped gate contact disposed on said first surface and surrounding and radially spaced from the exterior of said central emitter diffusion region and from the exterior of said flat cathode contact; said ring-shaped gate having an exterior periphery and an interior periphery; said ring-shaped gate contact having a short peripheral portion thereof extending from said interior periphery and electrically connected at said first surface to said short peripheral extending portion of the outer periphery of said central emitter diffusion region, thereby to provide a non-injecting current path for distributed capacitance current which flows from said ring gate during the application of forward biasing voltage to said controlled rectifier and further including an auxiliary emitter region in said first surface; said auxiliary emitter region at least partly underlying and connected to said ring gate and being spaced from said central emitter diffusion region; and an auxiliary gate connected to said first surface at a point spaced from said auxiliary emitter region.