Patent ID: 6660571
Filing Date: 2003-12-09
Classification: H01L

Abstract:
A method of forming a high voltage MOSFET comprising the steps of:providing a substrate of a first conductivity type; depositing an epitaxial layer on the substrate, said epitaxial layer having a first conductivity type; forming one or more body regions in the epitaxial layer to define a drift region therebetween, said body regions having a second conductivity type; forming one or more source regions of the first conductivity type in the body regions; and forming one or more trenches in said drift region of the epitaxial layer, said trenches extending toward the substrate from the body regions; forming a layer of silicon dioxide on the surfaces of said trenches; depositing polysilicon doped with a dopant of the second conductivity type over the silicon dioxide in said trenches to fill said trenches; diffusing at least a portion of said dopant from said trenches into portions of the epitaxial layer adjacent the trenches; and recrystallizing at least a portion of said polysilicon to form single crystal silicon.