| 摘要 |
PROBLEM TO BE SOLVED: To provide a horizontal type MOSFET having a high off-state withstanding voltage and a low on-resistance.SOLUTION: In a horizontal type MOSFET, a trench 2 is formed on a semiconductor substrate 1, and filled with an insulator 4 and a field plate 6. Drain drift layers 3 and 4 are formed on a lateral face and a bottom face of the trench. An impurity concentration of the drain drift layer 3 is set so that the impurity concentration in a region close to a drain region 11 is higher than that in a region away from the drain region 11. |
