| 摘要 |
PROBLEM TO BE SOLVED: To improve the breakdown voltage of the drain of an LD MOS transistor, without reducing the impurity concentration of its well region for drain and intermediate-concentration drain region. SOLUTION: A p-type low-concentration well region 22 is formed in a well region 21 for n-type drain which is formed in a p-type substrate 1. A p-type well region 23 for channel and an n-type intermediate-concentration drain region 24 containing impurities at a higher concentration than that of the well region 21 for n-type drain are formed with a space between them. A gate oxide film 11ox and a gate electrode 11g, extending from the well region 23 for p-type channel up to the n-type medium-concentration drain region 24 via the p-type low-concentration well region 22, are formed. An n-type source 11s is formed in the well region 23 for p-type channel next to the gate electrode 11g, and an n-type drain 11d is formed in the n-type medium-concentration drain region 24 provided with a space from the gate electrode 11g. COPYRIGHT: (C)2006,JPO&NCIPI
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