| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for forming a triple well of a semiconductor element with which the characteristic and reliability of semiconductor element can be improved by forming a triple well by using four well masks, so that the concentration of the respective well can be adjusted easily. SOLUTION: In this method for forming a triple well of a semiconductor element, a deep first N well 17 is formed in a semiconductor substrate 11 and a first P well 21 is formed shallow on the 17. Furthermore, a second N well, namely an R well, is formed on the shallow aside of the well 17, and a second P well 27 adjacent to the well 17 is formed shallow.
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