Semiconductor device

A semiconductor device comprising:

• a transistor region in which an insulated gate bipolar transistor having a gate electrode and an emitter electrode is provided;
• and
• a termination region arranged around the transistor region,
• wherein a first N type buffer layer is provided below an N type drift layer in the transistor region,
• a P type collector layer is provided below the first N type buffer layer,
• a second N type buffer layer is provided below the N type drift layer in the termination region,
• a collector electrode is directly connected to the P type collector layer and the second N type buffer layer,
• an impurity concentration of the second N type buffer layer decreases as a distance from the collector electrode decreases, and
• the second N type buffer layer does not form any ohmic contact with the collector electrode.

A semiconductor device comprising:

• a transistor region in which an insulated gate bipolar transistor having a gate electrode and an emitter electrode is provided;
• and
• a termination region arranged around the transistor region,
• wherein an N type buffer layer is provided below an N type drift layer in the transistor region and the termination region,
• a first P type collector layer is provided below the N type buffer layer in the transistor region,
• a second P type collector layer is provided below the N type buffer layer in the termination region,
• a collector electrode is connected to the first and second P type collector layers, and
• a peak impurity concentration of the second P type collector layer is higher than a peak impurity concentration of the N type drift layer and lower than a peak impurity concentration of the N type buffer layer.