| 摘要 |
PROBLEM TO BE SOLVED: To provide a technology which efficiently forms high withstand voltage transistors and low withstand voltage transistors on the same substrate and reduces the characteristics deterioration of each transistor. SOLUTION: An insulation film is formed firstly. The thickness of the insulation film of the high withstand voltage transistor on a drain-source forming region is thicker than that of the insulation film of the low withstand voltage transistor on the drain-source forming region. Next, gates are formed on the insulation film. Sidewalls are formed at the sides of the gates of the low withstand voltage transistors and an opening is formed in the insulation film on the drain-source forming region of each transistor. For forming openings in the comparatively thick insulation film on the drain-source forming region of the high withstand voltage transistor, etching is performed without reducing the width of the sidewall formed on the side of the gate of the lower withstand voltage transistor. An impurity element is introduced through the openings to form drain-source regions of the transistors.
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