Gate turn-off semiconductor controlled rectifier device with highly doped buffer region portion

Claim 1

A gate turn-off semiconductor controlled rectifier comprising: a cathode region having a one type conductivity adjacent a major surface of a body of semiconductor material, said cathode region extending a lateral distance across said surface; an active gate region having a second type conductivity adjacent said cathode region and forming a first PN junction at the interface therewith; a base region having said one type conductivity adjacent said active gate region and forming a second PN junction therewith, said base region being spaced apart from said cathode region by said active gate region; an anode region having said second type conductivity adjacent said base region and forming a third PN junction at the interface therewith, said anode region being spaced apart from said active gate region by said base region, said anode region also being adjacent another major surface of said body; a four-layer buffer section comprising the lateral extensions of said cathode, said active gate, said base and said anode regions; and a fifth region having said one type conductivity entirely within said lateral extension of said base region, said fifth region having a comparatively higher carrier concentration than said lateral extension of said base region, said fifth region being spaced apart from said lateral extensions of said active gate region and said anode region.