Patent ID: 8643092
Filing Date: 2014-02-04
Classification: H01L

Abstract:
1. 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 shielded trenched gates in said active area, wherein each said shielded trenched gate comprising a gate electrode disposed in the upper portion and a shielded electrode disposed in the lower potion, wherein said gate electrode and said shielded electrode insulated from each other by an inter-electrode insulation layer; said gate electrode in said shielded trenched gates connected to a gate metal formed over said insulation layer and said shielded electrode in said shielded trenched gates connected to a source metal formed over said insulation layer; each said shielded trenched gate in said active area further comprises a first type gate oxide along sidewalls of said gate electrode and a second type gate oxide surrounding bottom and sidewalls of said shielded electrode; multiple said trenched floating gates having floating voltage in parallel formed in termination area around outside of said active area and surrounded by said second type body regions and extending into said epitaxial layer, said trenched floating 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 of said trenched floating gates in said termination area having floating voltage; a drain metal on rear side of said substrate.