Semiconductor device and method of manufacturing the semiconductor device

A method of manufacturing a semiconductor device that includes a semiconductor substrate, an upper electrode, a lower electrode, and a gate electrode, the method comprising:

• forming a barrier region by implanting an n-type impurity in the semiconductor substrate;
• forming a pillar region by implanting an n-type impurity in the semiconductor substrate such that an average stop position of the n-type impurity is deeper than a top surface of the semiconductor substrate;
• and
• making the n-type impurity distribute to a position deeper than the average stop position of the n-type impurity when the barrier region is formed, wherein
• the upper electrode is formed on a top surface of the semiconductor substrate,
• the lower electrode is formed on a bottom surface of the semiconductor substrate,
• an emitter region, a body region, the pillar region, the barrier region, a drift region, a collector region and a cathode region are formed in the semiconductor substrate,
• the emitter region has an n-type impurity and is connected to the upper electrode,
• the body region has a p-type impurity, is formed on a lateral side and on a lower side of the emitter region and is connected to the upper electrode,
• the pillar region has an n-type impurity, is formed on a lateral side of the body region, extends along a depth from the top surface of the semiconductor substrate to a lower end of the body region, is connected to the upper electrode, and is separated from the emitter region by the body region,
• the barrier region has an n-type impurity, is formed on a lower side of the body region and the pillar region, and is separated from the emitter region by the body region,
• the drift region has an n-type impurity, is formed on a lower side of the barrier region, is separated from the emitter region by the barrier region, and has an n-type impurity concentration lower than an n-type impurity concentration of the pillar region and the barrier region,
• the collector region has a p-type impurity, is formed on a lower side of the drift region, is connected to the lower electrode, and is separated from the barrier region by the drift region,
• the cathode region has an n-type impurity, is formed on the lower side of the drift region, is connected to the lower electrode, is separated from the barrier region by the drift region, and has an n-type impurity concentration higher than the n-type impurity concentration in the drift region,
• a trench that penetrates through the emitter region, the body region and the barrier region and reaches the drift region is formed on the top surface of the semiconductor substrate,
• an inner surface of the trench is covered with a gate insulating film, and
• the gate electrode is disposed in the trench.