Patent ID: 8748976

Claim:
A semiconductor device, comprising: a substrate comprising semiconductor material; a vertical metal oxide semiconductor (MOS) transistor, including: a vertical drift region having a first conductivity type disposed in said semiconductor material of said substrate; at least one vertical RESURF trench in said substrate, such that instances of said vertical RESURF trench are disposed on opposite sides of said vertical drift region, in which each instance of said vertical RESURF trench includes: a dielectric trench liner disposed on sidewalls and a bottom of said vertical RESURF trench; a lower field plate disposed on said dielectric trench liner in a lower portion of said vertical RESURF trench; and an upper field plate disposed on said dielectric trench liner above said lower field plate, said dielectric trench liner being thicker between said lower field plate and said vertical drift region than said upper field plate and said vertical drift region; a drain contact region having said first conductivity type disposed in said substrate below said vertical RESURF trench; a gate disposed above said vertical drift region between said instances of said vertical RESURF trench disposed on opposite sides of said vertical drift region, such that said gate is electrically isolated from said upper field plate and said lower field plate; a source region having said first conductivity type disposed in said substrate above said vertical drift region and separated from said vertical drift region by a body region having a second conductivity type opposite from said first conductivity type; and a source electrode which is electrically coupled to said source region, said upper field plate and said lower field plate.