Patent ID: 6645815
Filing Date: 2003-11-11
Classification: H01L,Y10S

Abstract:
A method of forming a device comprising a plurality of trench MOSFET cells, said method comprising:providing a substrate of a first conductivity type; depositing an epitaxial layer of said first conductivity type over said substrate, said epitaxial layer having a lower majority carrier concentration than said substrate; etching trenches into said epitaxial region from an upper surface of said epitaxial layer; forming a first insulating region which lines at least a portion of said trenches; forming a conductive region within said trenches and adjacent said first insulating region; forming body regions of a second conductivity type within an upper portion of said epitaxial layer; forming source regions of said first conductivity type within upper portions of said body regions adjacent said trenches; forming a patterned implantation mask comprising a patterned second insulating region over said epitaxial layer, wherein said patterned implantation mask has apertures over at least portions of said body regions adjacent said sources, wherein said patterned implantation mask covers at least portions of said conductive region, and wherein said patterned implantation mask covers at least portions of said source regions; forming shallow dopant regions by a process comprising: (a) implanting a first dopant of said second conductivity type at a first energy level within upper portions of said body regions through said apertures and (b) diffusing said first dopant at elevated temperatures to a first depth from said upper surface of said epitaxial layer; forming deep dopant regions by a process comprising: (a) implanting a second dopant of said second conductivity type at a second energy level within upper portions of said body regions through said apertures and (b) diffusing said second dopant at elevated temperatures to a second depth from said upper surface of said epitaxial layer, wherein said first and second dopants can be the same or different, wherein said deep and shallow dopant regions each has a higher majority cater concentration than said body regions, wherein said second energy level is greater than said first energy level, and wherein said second depth is greater than said first depth; enlarging the apertures in said patterned second insulating region; and forming a conductive source contact adjacent upper surfaces of said source regions and upper surfaces of said shallow doped regions.