Power field effect devices having small cell size and low contact resistance

Claim 1

A multicellular, field effect, power semiconductor device comprising: a body of semiconductor material having opposed first and second major surfaces and a first region of one type conductivity extending to said first major surface; an insulated gate electrode disposed on said first major surface, said insulated gate electrode having a plurality of apertures therein; a plurality of cells, each associated with one of said apertures in said gate electrode, each of said cells including: a second region of opposite type conductivity extending into said first region from said first major surface beneath the gate-electrode aperture for that cell, a third region of said one type conductivity disposed in said second region and extending to said first major surface, said second and third regions being self-aligned with respect to the gate-electrode aperture for that cell, said second region including a channel portion disposed between said first and third regions, beneath said insulated gate electrode and self-aligned with respect to the gate-electrode aperture for that cell, and said second and third regions having a high conductivity layer selected from the group consisting of metals and metal-silicides disposed thereon in ohmic contact therewith, said high conductivity layer being self-aligned with respect to said aperture in said gate electrode and spaced from said gate electrode; a layer of dielectric material disposed over said body of semiconductor material and having a plurality of contact apertures therein, each of said contact apertures being situated over said high conductivity layer of a different cell, each of said contact apertures being substantially smaller in lateral extent than said high conductivity layer over which it is disposed; and a layer of metallization disposed over said dielectric layer, extending into each of said contact apertures and into ohmic contact with each of said high conductivity layers.