Semiconductor device, and method for manufacturing the same

A semiconductor device containing in a single chip a low withstanding voltage MOS transistor and a high withstanding voltage MOS transistor, wherein:

• the low withstanding voltage MOS transistor comprising
• a first gate oxide film having a first thickness,
• a first channel region formed below the first gate oxide film, and
• a first source/drain region formed across the first channel region, the first source/drain region including lightly doped drain extensions;
• the high withstanding voltage MOS transistor comprising
• a second gate oxide film having a second thickness which is greater than the first thickness,
• a second channel region formed below the second gate oxide film, and
• a second source/drain region formed across the second channel region, the second source/drain region including lightly doped drain extensions;
• the first channel region side end of the first source/drain region has an impurity profile differing from that of the second channel region side end of the second source/drain region;
• the first channel region side end of the first source/drain region has a junction depth of 1 μm or less;
• and
• the second channel region side end of the second source/drain region have a junction end of 1 μm or less,
• wherein the lightly doped drain extensions of the first source/drain region include the first channel region side end of the first source/drain region, and the lightly doped drain extensions of the second source/drain region include the second channel region side end of the second source/drain region.