Patent ID: 7989887

Claim:
A trench MOSFET with a plurality of transistor cells in active area and multiple trenched floating gates in termination area, comprising: a substrate of a first conductivity type; an epitaxial layer of said first conductivity type grown on said substrate, said epitaxial layer having a lower doping concentration than said substrate; a plurality of source regions of said first conductivity type formed near top surface of said epitaxial layer only within said active area, said source regions having a doping concentration higher than said epitaxial layer; a plurality of first type body regions of a second conductivity type formed beneath said source regions in said active area; a plurality of second type body regions of said second conductivity type formed into said epitaxial layer from top surface of said epitaxial layer around outside of said active area including said termination area; said source regions being not disposed in the top of said second type body regions; an insulation layer formed on said epitaxial layer; a plurality of first type gate trenches in active area surrounded by said source regions and said first type body regions, extending into said epitaxial layer and filled with gate conductive layer over gate oxide layer as first type trenched gates of said transistor cells for current conduction; at least one second type trenched gate having gate oxide layer formed thereon, said second trenched gate being wider and deeper than said first type trenched gates, surrounded by said second type body region and extending into said epitaxial layer and filled with gate conductive layer as trenched gates for gate connection; at least three third type trenched gates in parallel formed in termination area around outside of said active area having said gate oxide layer formed thereon, said third type trenched gates surrounded by said second type body region and extended into said epitaxial layer and filled with said gate conductive layer as trenched floating gates with floating voltage for sustaining breakdown voltage in termination area, said third type trenched gates having trench depth equal to or deeper than body junction of said second type body regions; each said second type body region between two adjacent said trenched floating gates in termination area having floating voltage; a plurality of trenched source-body contacts filled with metal plugs padded by a barrier layer, each penetrating through said insulation layer and one of said source regions and extending into one of said first type body regions between two adjacent said first type trenched gates, said metal plugs being connected to a first metal layer formed on said insulation layer as source metal; at least one trenched gate contact filled with said metal plug padded by said barrier layer, penetrating through said insulation layer and extending into said gate conductive layer, said metal plug being connected to a second metal layer on said insulation layer serving as gate metal; and a drain metal on rear side of said substrate.