Manufacturing method of semiconductor device

A semiconductor device comprising:

• a semiconductor substrate having a principal surface of a first conductivity type;
• a second conductivity type region formed on the principal surface of said semiconductor substrate having an island shape by introducing impurities of a second conductivity type;
• a highly doped first conductivity type region formed inside said second conductivity type region by introducing impurities of the first conductivity type at high concentration;
• a plurality of first trenches each extending from a surface of said highly doped first conductivity type region so as to reach at least said second conductivity type region on said first semiconductor substrate;
• an insulation film formed on an inner wall surface of each of the first trenches;
• an electrode portion made of polycrystalline silicon filled in each of the first trenches with said insulation film interposed therebetween;
• a plurality of second trenches formed inside said second conductivity type region so that each of the second trenches is positioned between an adjacent pair of said first trenches in parallel with said first trenches;
• and
• a second conductivity type protrusion region formed with a junction deeper than a junction of said second conductivity type region by introducing impurities of the second conductivity type through each of said second trenches by ion implantation.

A method of manufacturing a semiconductor device comprising:

• forming a second conductivity type region in a semiconductor substrate having a principal surface of a first conductivity type by implanting impurities of a second conductivity type two or more times;
• forming a first conductivity type region inside the island of said second conductivity type region, said first conductivity type region having a higher impurity concentration than said semiconductor substrate;
• forming a trench in a depth direction of said semiconductor substrate by anisotropic etching;
• forming a sacrificed oxide film on an inner wall surface of the trench by thermal oxidation;
• removing said sacrificed oxide film;
• forming an insulation film in an interior of said trench;
• and
• filling said trench formed said insulation film with a polycrystalline silicon film.

A method of manufacturing a semiconductor device comprising:

• forming a second conductivity type region, in a semiconductor substrate having a principal surface of a first conductivity type;
• forming a first conductivity type region inside said second conductivity type region, the first conductivity type region having a higher concentration than said semiconductor substrate;
• forming a plurality of first trenches in a depth direction of said semiconductor substrate by anisotropic etching;
• forming a sacrificed oxide film formed on an inner surface wall of each of the first trenches by thermal oxidation;
• removing said sacrificed oxide film;
• forming an insulation film in an interior of each of said first trenches;
• filling each of the first trenches with a polycrystalline silicon film;
• forming a plurality of second trenches in the second conductivity type region each positioned between an adjacent pair of said plurality of first trenches in parallel with said plurality of first trenches;
• forming a second conductivity type protrusion region with a junction deeper than a junction of said second conductivity type region by introducing impurities of the second conductivity type from each of the second trenches by two or more ion implantation steps;
• and
• forming a metal electrode so as to electrically connect said first conductivity type region with said second conductivity type protrusion region in each of the second trenches.