Integrated circuit with power transistor

Claim 1

An integrated semiconductor circuit having a high-current power transistor comprising: (a) a semiconductor substrate of one conductivity type; (b) an epitaxial layer of the opposite conductivity type on said substrate; (c) a closed annular isolation-wall region of said one type being formed in said epitaxial layer, said wall region extending through said epitaxial layer from the outer surface thereof to the interface between said epitaxial layer and said substrate, defining within said epitaxial layer a pocket-region; (d) an annular strip region of said one type being formed in said pocket region, extending from said surface only part way through said epitaxial layer, and being spaced inwardly from said wall region to serve as the base region of said transistor; (e) an elongated region of said opposite type being formed within and along said strip region and extending to said surface to serve as the emitter of said transistor; (f) a collector contact plug region of said opposite conductivity type being formed in a central portion of said pocket, being spaced inwardly from said annular strip region, extending from said surface through said epitaxial layer, and having at the periphery thereof a substantially greater electrical conductivity than that of the immediately adjacent portion of said pocket region; (g) a metal collector-termination pad overlying and contacting said plug region at said surface, the periphery of said metal pad being substantially coincident with said periphery of said underlying plug region, said collector-termination pad having an area no smaller than 10 4 square microns; (h) one metal layer contacting at said surface said elongated emitter region substantially along the entire length thereof; and (i) another metal layer contacting at said surface said base strip region essentially along the entire length thereof, said another layer lying between and being spaced from said collector termination pad and said one metal layer.