SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

摘要

PROBLEM TO BE SOLVED: To optimize the impurity concentration of wells in a well isolation region, and the impurity concentration of normal wells in a semiconductor integrated circuit device having a well isolation structure. SOLUTION: Buried n-type wells 3a and 3b are respectively provided in a well isolation region and a second well region, shallow p-type wells 4a and 4b of an impurity concentration set independently of the n-type wells 3a and 3b are respectively provided directly over the wells 3a and 3b in a self alignment manner and the shallow well 4a in the well isolation region is encircled with shallow n-type wells 5a formed on the side surface sides of the well 4a in a state that the well 4a is connected electrically with the n-type well 3a is separated electrically from a semiconductor substrate 1.