Patent ID: 9530882
Filing Date: 2016-12-27
CPC Classification: H01L

Claim Text:
1. A trench MOSFET comprising a plurality of unit cells with each unit cell in an active area comprising: at least one gate trench surrounding a deep trench as a closed cell shape, wherein said deep trench comprising a shielded gate formed inside; a trenched source-body contact disposed between said gate trench and said deep trench; and a substrate of a first conductivity type; an epitaxial layer of said first conductivity type onto said substrate, wherein said epitaxial layer has a lower doping concentration than said substrate; said deep trench having a greater trench depth than said gate trench; said shielded gate being formed within said deep trench and surrounded with a dielectric material; a mesa area between a pair of adjacent deep trenches; a diffused drift region of said first conductivity type formed in said mesa area and having a higher doping concentration than said epitaxial layer, wherein said diffused drift region has a higher doping concentration near trench sidewalls of said deep trench than in the center of said mesa area; a source region of said first conductivity type extending between said deep trenches and surrounding sidewalls of said gate trench above a body region of a second conductivity type; said gate trench filled with gate electrode padded by a gate insulation layer, starting from top surface of said epitaxial layer and down penetrating through said source region, said body region and extending into said diffused drift region in said mesa area, wherein said gate insulation layer has a thickness thinner than said dielectric material; and a source metal connected with the shielded gate through a shielded gate contact and connected with the source region through the trenched source-body contact.