| 摘要 |
PROBLEM TO BE SOLVED: To obtain an insulated gate N-channel field effect type transistor having high breakdown voltage and a high ESD endurance strength without increasing a process and a circuit, and the body potential of an element can be set freely without recourse to semiconductor substrate potential in a BiCMOS integrated circuit. SOLUTION: This semiconductor device has a P-type well layer 4 around the drain region of the insulating gate field effect transistor formed on the N-type epitaxial layer 2 on a P-type semiconductor substrate 1, an N-type buried layer 13 located under an element, and a P-type buried layer 3 located inside the N-type buried layer on a level when viewed horizontally, on the lower side and the upper side of the N-type buried layer in depthwise direction and having the width coming into contact with the P-type well layer. |
