Patent ID: 6133606
Filing Date: 2000-10-17
Classification: H01L,Y10S

Abstract:
A high voltage semiconductor device, comprising:a semiconductor substrate;a first trench formed inside said substrate to a first depth;a second trench formed inside said substrate to a second depth;a pair of source and drain regions formed on the left side and right side of said first trench and said second trench respectively, moreover, said pair of source and drain regions being formed within said substrate and having a depth approximately equal to said second depth of said second trench;a first doping region formed within said pair of source and drain regions, wherein the conductivity type of a first dopant is opposite the conductivity type of said substrate;a second doping region formed within said pair of source and drain regions and positioned directly above said first doping region, wherein the conductivity type of a second dopant is the same as the conductivity type of said first doping region, moreover, the doping density of said second doping region is higher than the doping density of said first doping region;a third doping region formed within said pair of source and drain regions and positioned directly above said second doping region, wherein the top surface of said third doping region is the uppermost surface of said pair of source and drain regions, the conductivity type of a third dopant being the same as the conductivity type of said second doping region, moreover, the doping density of said third doping region being higher than the doping density of said second doping region;a spacer formed on sidewalls of said first trench and also occupies a bottom portion of said first trench;a gate oxide layer formed on sidewalls and on a bottom surface of said second trench;a buried gate electrode formed on top of said gate oxide layer and also fills up said first trench and said second trench, wherein the top surface of said buried gate electrode has a height almost equal to the uppermost surface of said pair of source and drain regions.