Patent ID: 9018701
Filing Date: 2015-04-28
Classification: H01L

Abstract:
1. A power semiconductor device comprising a plurality of trench MOSFETs with each comprising: a substrate of a first conductivity doping type; an epitaxial layer of said first conductivity type over said substrate, wherein said epitaxial layer having a lower doping concentration than said substrate; a plurality of trenched gates comprising a doped poly-silicon layer padded by a gate oxide layer filling into a plurality of gate trenches; a body region of a second conductivity type surrounding sidewall of each of said gate trenches between every two adjacent of said trenched gates; a source region of said first conductivity type near top surface of said body region, wherein said source region surrounds top portion of sidewall of each of said gate trenches, and has a higher doping concentration than said epitaxial layer; a contact insulation layer disposed over said epitaxial layer and covering outer surface of said trenched gates; a trenched source-body contact structure comprising a metal plug padded by a barrier layer filling into a contact opening, locating between every two adjacent of said trenched gates, penetrating through said contact insulation layer and said source region, and extended into said body region; a body ohmic contact doped region of said second conductivity type formed within said body region, surrounding at least bottom of said trenched source-body contact structure and having a higher doping concentration than said body region; at least two avalanche capability enhancement doped regions of said second conductivity type disposed underneath said body ohmic contact doped region, wherein among said at least two avalanche capability enhancement doped region, the bottom one is formed partially overlap with said body region and partially extending into said epitaxial layer but shallower than said gate trenches while the else being formed within said body region, wherein said at least two avalanche capability enhancement doped region have a higher doping concentration than said body region but a lower doping concentration than said body ohmic contact doped region; a source metal disposed covering top surface of said contact insulation layer; a drain metal disposed on back surface of said substrate; and said source region having a doping concentration along sidewalls of said trenched source-body contact structure higher than along an adjacent channel region near said gate trenches at a same distance from a top surface of said epitaxial layer, and said source region having a junction depth along the sidewalls of said trenched source-body contact structure greater than along said adjacent channel region from the top surface of said epitaxial layer.