Importance

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Abstract

A trench MOS-gated device comprises a doped monocrystalline semiconductor substrate that includes an upper layer and is of a first conduction type. An extended trench in the upper layer of the substrate has a bottom portion filled with a dielectric material that forms a thick layer in the bottom of the trench. The upper portion of the trench is lined with a dielectric material and substantially filled with a conductive material, the filled upper portion of the trench forming a gate region. An extended doped zone of a second opposite conduction type extends from the upper surface into the upper layer on one side of the trench, and a doped well region of the second conduction type overlying a drain zone of the first conduction type is disposed in the upper layer on the opposite side of the trench. The drain zone is substantially insulated from the extended zone by the thick dielectric layer in the bottom portion of the trench. A heavily doped source region of the first conduction type and a heavily doped body region of the second conduction type is disposed in the well region at the upper surface of the upper layer. An interlevel dielectric layer is disposed on the upper surface overlying the gate and source regions, and a metal layer overlying the upper surface and the interlevel dielectric layer is in electrical contact with the source and body regions and the extended zone. A process for constructing a trench MOS-gated device comprises forming an extended trench in an upper layer of a doped monocrystalline semiconductor substrate of a first conduction type, and substantially filling the trench with a dielectric material. A dopant of a second opposite conduction type is implanted and diffused into the upper layer on one side of the extended trench to form a doped extended zone extending into the upper layer from its upper surface. A selected portion of the dielectric material is removed from an upper portion of the trench, leaving a thick dielectric layer in its bottom portion. Sidewalls comprising dielectric material are formed in the upper portion of the trench, which is then substantially filled with a conductive material to form a gate region in the upper portion of the trench. A doped well region of the second conduction type is formed in the upper layer on the side of the trench opposite the doped extended zone. Heavily doped source and body regions are formed in the well region, and an interlevel dielectric layer is deposited on the upper surface overlying the gate and source regions. A metal layer in electrical contact with the source and body regions and the extended zone is formed over the substrate upper surface and the interlevel dielectric layer.

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First Claim