Patent ID: 6541318
Filing Date: 2003-04-01
Classification: H01L

Abstract:
Process of manufacturing a semiconductor device comprising a step of forming recessed zones in a semiconductor layer of a first conductivity type, a step of oxidation for forming a gate oxide layer at the sidewalls of said recessed zones, a step of forming a polysilicon gate electrode inside said recessed zones, a step of forming body regions of a second conductivity type in said semiconductor layer between said recessed zones, and a step of forming source regions of the first conductivity type in said body regions, wherein said step of forming recessed zones comprises a step of local oxidation of the surface of said semiconductor layer wherein said recessed zones will be formed, with an oxide growth on and into said semiconductor layer in order to obtain thick oxide regions penetrating in said semiconductor layer, and a step of etching wherein the oxide of said thick oxide regions is removed;wherein said step of forming recessed zones comprises a step of forming a nitride layer over the upper surface of said semiconductor layer, a step of forming openings in said nitride layer, and finally a step of removing said nitride layer after said step of etching said thick oxide regions; wherein said step of forming recessed zones comprises a step of introducing dopant of the first conductivity type through said openings in order to form first doped regions, before said step of local oxidation; wherein under said recessed zones formed by removing said thick oxide regions there are enrichment regions of the first conductivity type, derived from said step of introducing dopant of the first conductivity type, previous to said step of oxidation for forming said thick oxide regions.