Semiconductor device with alternating conductivity type layers having different vertical impurity concentration profiles

A power semiconductor device comprising:

• a first semiconductor layer of a first conductivity type;
• a first main electrode electrically connected to the first semiconductor layer;
• second semiconductor layers of a second conductivity type formed within the first semiconductor layer and periodically arranged in a lateral direction, a profile of an amount of an impurity in a vertical direction of the second semiconductor layers being differ from a profile of an amount of the impurity in the vertical direction of the first semiconductor layer;
• a third semiconductor layer of the second conductivity type selectively formed in surfaces of the first semiconductor layer and the second semiconductor layer;
• a fourth semiconductor layer of the first conductivity type selectively formed in a surface of the third semiconductor layer;
• a second main electrode formed to be connected to the surface of the third semiconductor layer and a surface of the fourth semiconductor layer;
• and
• a control electrode formed on the first semiconductor layer, the third semiconductor layer and the fourth semiconductor layer with a gate insulating film interposed therebetween,
• wherein the first semiconductor layer has a constant concentration of the impurity in a vertical direction from the second main electrode to the first main electrode;
• and
• the second semiconductor layer has a concentration of the impurity distributed such that the impurity concentration is decreased in the vertical direction from the second main electrode to the first main electrode.