Asymmetrical field controlled thyristor

Claim 1

An asymmetrical field controlled thyristor comprising: a semiconductor substrate (32) of one type conductivity; a dual-layer base region (30, 31) adjoining said substrate and being comprised of an integral portion of said semiconductor material with opposite type conductivity, the layer (31) of said dual-layer base region closest to said substrate being doped at a higher concentration of opposite conductivity type determining dopants than the layer (30) of said dual-layer base region farthest from said substrate; a cathode region (34) adjoining said layer of said dual-layer base region farthest from said substrate and being comprised of said semiconductor material of said opposite type conductivity, said cathode region being doped at a higher concentration of said opposite conductivity type-determining dopants than the layer of said dual-layer base region closest to said substrate; a semiconductor gate region (33) spaced apart from said cathode region, aaid gate region adjoining said layer of said dual-layer base region farthest from said substrate and being comprised of said semiconductor material of said one type conductivity; first conductive means (35) contacting the outermost surface of said cathode region; second conductive means (36) contacting the outermost surface of said gate regions; and third conductive means (37) contacting the outermost surface of said substrate of one type conductivity.

Claim 5

The apparatus of Claims 1 or 2 or 3 characterized in that each of said conductive means comprises a respective layer of aluminum.

Claim 6

The apparatus of any one of the preceding claims characterized in that there are a plurality of gate regions spaced apart from said cathode region on either side thereof.

Claim 7

The apparatus of Claim characterized in that the remainder of the outermost surface has a passivation layer.

Claim 8

A method of fabricating an asymmetrical field controlled thyristor characterized by the steps of: (a) oxidizing a major surface of a semiconductor substrate of one type conductivity having two major surfaces; (b) diffusing dopants into the unoxidized major surface of said substrate to form a more heavily doped layer in said semiconductor substrate than the remaining portion of said substrate, said more heavily doped layer being of the same type conductivity as that of the remaining portion of said substrate; (c) patterning the oxide layer to open a gate diffusion area therein; (d) diffusing dopants into said substrate through both of said major surfaces so as to produce gate region of opposite type conductivity adjoining said remaining portion of said substrate and an anode region of said opposite type conductivity adjoining said more heavily doped layer in said substrate; (e) patterning said oxide layer to open only a cathode diffusion area therein; (f) diffusing dopants into said substrate through said cathode diffusion area opened in said oxide layer so as to provide a cathode region of said one type conductivity adjoining said remaining portion of said substrate; (g) applying a layer of metal onto the outermost surfaces, respectively, of said cathode region and said gate region so as to obtain separate contacts to said cathode region and to said gate region, respectively; and (h) applying a layer of metal onto the outermost surface of said anode region.

Claim 9

A method of fabricating an asymmetrical field controlled thyristor characterized by the steps of: (a) oxidizing a major surface of a semiconductor substrate of one type conductivity having two major surfaces; (b) diffusing dopants into the unoxidized major surface of said substrate to form a more heavily doped layer in said semiconductor substrate than the remaining portion of said substrate, said more heavily doped layer being of the same type conductivity as that of the remaining portion of said substrate; (c) patterning the oxide layer to open a gate diffusion area therein; (d) diffusing dopants into said substrate through both of said major surfaces so as to produce gate region of opposite type conductivity adjoining said remaining portion of said substrate and an anode region of said opposite type conductivity adjoining said more heavily doped layer in said substrate; (e) patterning said oxide layer to open only a cathode diffusion area therein; (f) diffusing dopants into said substrate through said cathode diffusion area opened in said oxide layer so as to provide a cathode region of said one type conductivity adjoining said remaining portion of said substrate; (g) applying a layer of metal onto the outermost surfaces, respectively, of said cathode region and said gate region so as to obtain separate contacts to said cathode region and to said gate region, respectively; and (h) applying a layer of metal onto the outermost surface of said anode region.

Claim 11

The method of Claims 7 or 8 characterized in that the metal comprises aluminum.

Claim 12

The method of any one of Claims 7 or 8 or 9 characterized in that the patterning step (c) provides a plurality of gate diffusion areas and the diffusion step (d) provides a plurality of gate regions.