Integrated transverse and triggering lateral thyristors

Claim 2

A semiconductor integrated circuit as set forth in claim 1 wherein the third further region and the first further region are each diffused regions having the same impurity distribution decreasing from the said one surface into the bulk.

Claim 3

A semiconductor integrated circuit of the planar type comprising a semiconductor body having a transverse thyristor formed by first, second, third and fourth successively arranged regions of alternating conductivity type extending between opposite major surfaces of the body and defining three PN junctions therebetween, two main current carrying electrodes, one of said main electrodes being in ohmic connection with the first region of the one conductivity type at one major surface and the other of said main electrodes being in ohmic connection with the fourth region which is of the opposite conductivity type whereby a main current carrying path is provided between said electrodes through the transverse thyristor formed by said four regions and said three PN junctions and extending transversely to the major surface and through the body, the said first region being completely surrounded within the body by the said second region with the PN junction therebetween terminating at the one surface, each of the first and second regions comprising diffused regions having an impurity distribution decreasing from the said one surface into the bulk of the body, said third region completely surrounding the second region, said fourth region completely surrounding the third region, the PN junctions between the third and second regions and between the fourth and third regions terminating at the said one surface underneath the insulating layer, first and second further regions of alternating conductivity type Provided within the second region and being diffused regions with said second further region having an impurity distribution the same as that of the first region, said second further region completely surrounding said first further region forming a PN junction therebetween also terminating at the said one surface, an insulating layer on the said one surface covering the PN junctions terminating thereat, said first further and said second further regions forming with the first and second regions four successively arranged regions alternating in conductivity type forming a triggering lateral thyristor having a triggering current path extending substantially parallel to said one surface, a control electrode in ohmic connection with the first further region at the one surface thereby to provide a lateral thyristor for switching the transverse thyristor from a high-impedance, nonconductive state to a low-impedance, conductive state, a third further surface region of the same conductivity type as the first further region provided within the second further region and completely surrounded by the latter with the PN junction formed with the latter terminating at the said one surface underneath the insulating layer, and means connecting said third further region to the first region to thereby provide a Zener diode to stabilize the turn-on voltage of the lateral thyristor.