| 摘要 |
PURPOSE:To improve the secondary breakdown strength of a vertical type power MOS FET by a method wherein a diode region, composed of the region with a deep diffusion depth and the region with a shallow diffusion depth, is provided at a distance from the 2nd conductivity type region of the FET region in the MOS FET. CONSTITUTION:A diode region is formed on the surface of the 1st conductivity type low concentration drain region 1a at a distance from the 2nd conductivity type semiconductor region 2 of an FET region. The diode region is composed of the 2nd conductivity type semiconductor region 22 with a shallow diffusion depth and the 2nd conductivity type semiconductor region 23 with a deep diffusion depth. The depth of the deep region 23 is nearly equal to the depth of the second conductivity type region 2 of the FET region. With this constitution, an avalanche multiplication phenomenon can be induced in the diode regions 22 and 23 provided at a distance from the parasitic transistor of the FET region so that the secondary breakdown strength of the FET can be improved. |
