High voltage mosgated device with trenches to reduce on-resistance

A high voltage MOSgated device of low on-resistance comprising, in combination;

• a thin flat chip of silicon having a main body layer of one conductivity type and having relatively high concentration and a junction-receiving layer of said one conductivity type and of a relatively lower concentration disposed atop said main body layer;
• a plurality of spaced base diffusions of the other conductivity type formed in the upper surface of said junction receiving layer and a plurality of source regions of said one conductivity type formed in respective ones of said base diffusions to define invertable channel regions laterally spaced from one another by a vertical conduction channel region in said junction receiving layer;
• and a MOSgate structure disposed above each of said invertible channels and responsive to a suitable MOSgate input signal;
• a plurality of spaced thin trenches extending vertically from the top of said junction receiving layer for at least a major portion of the thickness of said junction receiving layer;
• a first main contact disposed above the top surface of said junction receiving layer and in contact with said source and base diffusions and said trenches;
• a second main contact formed on the bottom of said main body layer;
• said trenches defining between them vertical depletable vertical conduction regions in said junction receiving layer for the length of said trenches;
• each of said trenches being filled with a semi-insulating, non-injecting material which is relatively incapable of carrier injection into the junction receiving layer.