Semiconductor device comprising a transistor cell including a source contact in a trench, method for manufacturing the semiconductor device and integrated circuit

A method of manufacturing a semiconductor device comprising a transistor cell in a semiconductor substrate having a first main surface and a second main surface, the method comprising:

• forming a source region;
• forming a source contact electrically connected to the source region, the source contact comprising a first source contact portion and a second source contact portion, the second source contact portion being disposed at the second main surface;
• forming a drain region;
• forming a body region;
• and
• forming a gate electrode in a gate trench in the first main surface adjacent to the body region, the gate electrode being configured to control a conductivity of a channel formed in the body region, a longitudinal axis of the gate trench extending in a first direction parallel to the first main surface,
• the source region, the body region and the drain region being disposed along the first direction,
• forming the first source contact portion comprises forming a source contact groove in the first main surface of the semiconductor substrate to a depth larger than a depth of the gate trench, and filling the source contact groove with a source conductive material such that the source conductive material is in direct contact with the source region, wherein the source conductive material extends partially into a first doped portion of the semiconductor substrate, and wherein the first doped portion includes a region arranged between the source conductive material and the second source contact portion;
• forming the semiconductor substrate, wherein the semiconductor substrate comprises the first doped portion and a second doped portion having a same conductivity type, the first doped portion having a larger distance to the first main surface than the second doped portion, the first doped portion having a larger doping concentration than the second doped portion, the first doped portion being in direct contact with the first source contact portion;
• and
• forming a drain contact electrically connected to the drain region, the drain contact being disposed in a drain contact groove, and wherein the drain contact groove at least partially extends into the second doped portion of the semiconductor substrate.