Patent ID: 7704864

Claim:
A method of manufacturing a semiconductor device comprising: providing a semiconductor substrate having first and second main surfaces opposite to each other, the semiconductor substrate having a heavily doped region of a first conductivity type at the second main surface and having a lightly doped region of the first conductivity type at the first main surface; forming a plurality of trenches and a plurality of mesas in an active region of the substrate, each trench having a first extending portion extending from the first main surface toward the heavily doped region to a first depth position, each mesa having a sidewall surface, each of the plurality of trenches being separated from each of the other trenches by one of the plurality of mesas; forming a dielectric layer over a selected area of the plurality of mesas and the plurality of trenches in the active region and extending into a termination region of the substrate which is outside and adjacent to the active region, until the dielectric layer covers the top of each mesa within the selected area of the plurality of mesas, the sidewalls and the bottoms of each of the plurality of trenches and the top of the termination region; removing the dielectric layer from the selected area of the plurality of mesas and the plurality of trenches to remove the dielectric layer in the bottoms of the plurality of trenches; forming a protective shield over a region at a border between the active region and the termination region; partially removing the protective shield from over the selected area of the plurality of mesas and the plurality of trenches; ion implanting a dopant of the first conductivity type into at least one mesa of the selected area of the plurality of mesas and the plurality of trenches, at an adjacent pair of the plurality of trenches at a sidewall surface of one trench to form at the sidewall surface of the one trench a first doped region of the first conductivity type having a doping concentration lower than that of the heavily doped region; and ion implanting a dopant of the second conductivity type into the at least one mesa of the selected area of the plurality of mesas and the plurality of trenches, at a sidewall surface of the at least one mesa opposite to the sidewall implanted with the dopant of the first conductivity type to provide a second doped region of the second conductivity type at the sidewall surface opposite to the sidewall implanted with the dopant of the first conductivity type.