Patent ID: 6878603

Claim:
A process for manufacturing a DMOS transistor ( 100 ) with a semiconductor body ( 5 ), which features a surface layer with a source region ( 10 ) and a drain region ( 80 ) of a second conductivity type, and a first well region ( 20 ) of a first conductivity type directly adjoining and enclosing the source region ( 10 ), wherein a gate region ( 35 ) is formed on the surface of the surface layer of the semiconductor body ( 5 ), which gate region extends from the source region across at least part of the well region ( 20 ), said method comprising: starting on the surface of the semiconductor body ( 5 ), forming a trench-shaped structure in the surface layer by carrying out a dry plasma etching process, such that the trench-shaped structure includes a floor region, a source-end side wall extending from the floor region to the surface on a first side of the trench-shaped structure proximate to the source region, and a drain-end side wall on a second side of the trench-shaped structure proximate to the drain region, wherein said drain-end side wall region, said floor region and said source-end side wall region are continuous with one another and together form a drift region of said DMOS transistor, and wherein at least one of the side walls slopes non-perpendicularly relative to the surface so that the trench-shaped structure has a tapering cross-section with a greater width at the surface than at the floor region, wherein said width at the surface is greater than a death of said trench-shaped structure, and wherein said trench-shaped structure is located within an active portion of said DMOS transistor between said source region and said drain region; producing a doping of the second conductivity type with a first concentration value in the floor region of the trench-shaped structure; producing a doping of the second conductivity type with a second concentration value in the source-end side wall of the trench-shaped structure; and producing a doping of the second conductivity type with a third concentration value in the drain-end side wall of the trench-shaped structure; wherein at least one of said concentration values is different from the others of said concentration values.