Patent ID: 7015104

Claim:
A method of manufacturing a semiconductor device comprising the steps of: providing a semiconductor substrate having first and second main surfaces opposite to each other, said semiconductor substrate having a heavily doped region of a first conductivity type at said second main surface and having a lightly doped region of the first conductivity type at said first main surface side; providing in said semiconductor substrate a plurality of trenches, with each trench having a first extending portion extending from said first main surface towards said heavily doped region to a first depth position, each trench having a first sidewall surface and a second sidewall surface in parallel alignment with the first sidewall surface; forming a blocking layer on the first and second sidewalls and the bottom of each trench; obliquely implanting a dopant of a second conductivity type into the first sidewall surface to form a first doped region of the second conductivity type at the first sidewall surface; obliquely implanting a dopant of the second conductivity type into the second sidewall surface, to provide a second doped region of the second conductivity type at the second surface; removing the blocking layer from the first and second sidewalls and bottoms of each trench; etching the bottoms of the trench to remove any implanted dopants of the second conductivity type; diffusing the implanted dopant of the second conductivity type; and filling the trenches.