CMOS device and method of manufacturing the same

摘要

A semiconductor substrate having a first conductivity type is first prepared. Then, a well region is formed in the substrate so as to have a second conductivity type opposite to the first conductivity type. Next, a first ion having the first conductivity type is implanted into the well region to form a region to be a first drain region having a first impurity density and into the substrate to form a region to be a first channel stopper region. Next, a second ion having the second conductivity type is implanted into the well to form a region to be a second channel stopper region and into the substrate to form a region to be a the second drain region having a second impurity density. Then, the respective ion implanted regions are thermally diffused to form the first drain region and the second channel stopper region in the well region and to form the second drain region and the first channel stopper region in the substrate. Next, a third drain region is formed in the first drain region so as to have the first conductivity type and a third impurity density higher than the first impurity density. And a fourth drain region is formed in the second drain region so as to have the second conductivity type and a fourth impurity density higher than the second impurity density.