| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To enable a power semiconductor device, such as an IGBT and a diode, to make turning off fast and soft switching compatibly. <P>SOLUTION: An n-type main semiconductor layer 31 is provided with an n-type low-density semiconductor layer 34a and an n-type ultra-low-density semiconductor layer 34b having a lower impurity density than it in a region between a p-channel layer 32 and a field stop layer 35 repeatedly and alternately in a direction parallel to a first principal surface of the n-type semiconductor layer 31. The n-type low-density semiconductor layer 34a suppresses spreading of a space charge region in a turn-off state. The n-type ultra-low-density semiconductor layer 34b pushes and spreads the space charger region in the turn-off state to quickly discharge electrons and holes, achieving high-speed turn-off operation. An arrangement pattern of the n-type low-density semiconductor layer 34a and the n-type ultra-low-density semiconductor layer 34b is independent of an arrangement pattern of a gate electrode structure. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
