Semiconductor switching device with segmented sources

A semiconductor switching device comprising:

• a substrate of silicon of a first conductivity type provided at a first face with a first doped region of a second conductivity type opposite to that of said first conductivity type and at a second, opposite face with strips of doped material of said second conductivity type therein to form base regions;
• segmented regions of material of said second conductivity type lying wholly within the lateral bounds of each of said strips and aligned therewith to include in each case a first margin of width on each side of each of the segmented regions towards each of the boundaries of a corresponding strip, said segmented regions being more highly doped than said strips;
• and
• further doped regions, of material of said first conductivity type, separating said segmented regions and including in each case a second margin of width on each side of each of the further doped regions towards each of the boundaries of a corresponding strip, said first and second margins being for a metal-insulator-silicon gated channel in the material of said second conductivity type between each of said further regions and said substrate and the surfaces of said segmented regions and said further regions being provided with a common ohmically connected contact for use as a source terminal, wherein the length of an edge of each of said segmented regions parallel to a boundary direction of the corresponding one of said strips is not more than twice the width of said second margin.