| 摘要 |
PURPOSE:To improve breakdown strength and to prevent a narrow channel effect, by utilizing a side wall formed on the side of a protruding region, thereby forming channel stopper regions, and isolating the regions from an impurity region of an element forming region both the vertical and lateral directions. CONSTITUTION:A side wall 18 is formed on the side 15 of a protruding region 14. A source/drain region 22 of an element and channel stopper regions 19 are vertically isolated from step parts. Therefore, the defect that a breakdown voltage becomes low is prevented, and high breakdown strength is realized. A narrow channel effect is also prevented effectively. The channel stopper regions 19 are formed so that are laterally isolated from the side wall. The direct contact of the source/drain region 22 and the channel stopper regions 19 is prevented, and the decrease in breakdown strength is prevented. The narrow channel effect, in which the channel stopper regions 19 are expanded in the lateral direction and a threshold voltage value Vth becomes high, is effectively prevented together with the vertical isolation.
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