SEMICONDUCTOR DEVICE AND ITS MANUFACTURING METHOD

PROBLEM TO BE SOLVED: To provide a semiconductor device wherein the driving performance of a low-voltage high-driving performance transistor is not deteriorated by making the height of a side wall the same in a high breakdown voltage transistor and in the low-voltage high-driving performance transistor, and raising the junction breakdown voltage and an operating breakdown voltage of the high breakdown voltage transistor. SOLUTION: An ion injection density in a gate electrode 7 of the high breakdown voltage transistor is higher than that in a gate electrode 7 of the low-voltage high-driving performance transistor. The thickness of a side wall oxide film 8 formed on a side wall by oxidizing the gate electrode 7 is larger in the high breakdown voltage transistor than in the low-voltage high-driving performance transistor. The thickness of the side wall 9 formed on the side wall of the gate electrode 7 via the side wall oxide film 8 is the same in both transistors. COPYRIGHT: (C)2005,JPO&NCIPI