Patent ID: 7843004
Filing Date: 2010-11-30
Classification: H01L

Abstract:
1. A MOSFET formed in a semiconductor die comprising: a gate trench extending from a surface of the die, the gate trench comprising a gate electrode, the gate electrode being insulated from the die by a first dielectric layer, the first dielectric layer comprising a first section at a bottom of the gate trench and a second section at a sidewall of the gate trench, the first section being thicker than the second section; a first recessed field plate (RFP) trench extending from the surface of the die, the first RFP trench containing a first RFP electrode having an upper surface which is recessed below an upper surface of said gate electrode and which is insulated from the die by a second dielectric layer; a second RFP trench extending from the surface of the die, the second RFP trench containing a second RFP electrode which is also insulated from the die, the gate trench being located between the first and second RFP trenches; a mesa of the die between the gate trench and the first RFP trench; a source region of a first conductivity type in the mesa adjacent to the surface of the die and a sidewall of the gate trench; a body region, having a second conductivity type opposite to the first conductivity type, adjacent to the sidewall of the gate trench and to the source region; a body contact region, abutting said first and second RFP trenches and said body region, a drain-drift region of the first conductivity type adjacent to the body region; wherein the respective bottoms of the first and second RFP electrodes are located at a level deeper below the surface of the die than a bottom of the gate electrode.