Reverse-conducting insulated-gate bipolar transistor structure and corresponding fabrication method thereof

A reverse-conducting insulated-gate bipolar transistor structure, comprising:

• an emitter electrode located at the front surface,
• a plurality of cell structures located under the emitter electrode,
• a first conductive type drift region located under the cell structures,
• a collector electrode located at the back surface,
• more than one trench, the trenches being located at the back surface and filled by the collector electrode,
• a mechanical support semiconductor region located between the trenches,
• a second conductive type collector region, the second conductive type collector region being located at the top of each trench and connected to the collector electrode,
• a first conductive type buffer region, the first conductive type buffer region being located on top of each second conductive type collector region and below the first conductive type drift region, and the first conductive type buffer region separating the drift region from the collector region;
• and
• a first conductive type cathode region, the first conductive type cathode region being a part of the mechanical support semiconductor region at the sidewall of each trench and connected to the collector electrode,
• wherein the trenches have a hexagonal top view.