Technique for forming the deep doped columns in superjunction

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 side;
• providing in the semiconductor substrate a plurality of trenches, with each trench having a first extending portion extending from the first main surface towards the heavily doped region to a first depth position, each trench having a first sidewall surface and a second sidewall surface;
• forming an blocking layer on the first and second sidewalls and the bottom of each trench;
• implanting a dopant of a second conductivity type into the first sidewall surface at a first angle that is less than the tangent of the depth of the trench to the width of a side of the trench that is at a right angle to the first sidewall surface to form a first doped region of the second conductivity type at the first sidewall surface;
• implanting a dopant of the second conductivity type into the second sidewall surface at a second angle that is ninety degrees larger than the first angle, 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;
• diffusing the implanted dopant of the second conductivity type;
• and
• filling the trenches.

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 side;
• providing in the semiconductor substrate a plurality of trenches, with each trench having a first extending portion extending from the first main surface towards the heavily doped region to a first depth position, each trench having a first sidewall surface and a second sidewall surface;
• forming a blocking layer on the first and second sidewalls and the bottom of each trench;
• doping the first sidewall surface with a dopant of a second conductivity type to form a first doped region of the second conductivity type at the first sidewall surface;
• doping the second sidewall surface with a dopant of the second conductivity type to form a second doped region of the second conductivity type at the second surface;
• and
• removing the blocking layer from the first and second sidewalls and bottoms of each trench.

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 side;
• providing in the semiconductor substrate a plurality of trenches, with each trench having a first extending portion extending from the first main surface towards the heavily doped region to a first depth position, each trench having a first sidewall surface and a second sidewall surface;
• forming a blocking layer of silicon dioxide on the first and second sidewalls and the bottom of each trench, the blocking layer having a thickness of about 400-2000 Angstroms (Å);
• implanting a dopant of a second conductivity type into the first sidewall surface at an angle α to form a first doped region of the second conductivity type at the first sidewall surface;
• implanting a dopant of the second conductivity type into the second sidewall surface at an angle α minus 90 degrees 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 by etching;
• 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 with doped or undoped polysilicon.