Semiconductor device and manufacturing method thereof

A manufacturing method of a semiconductor device having, on a semiconductor substrate, a first field-effect transistor and a second field-effect transistor which has a higher voltage resistance than the first field-effect transistor wherein at least one of a source region and a drain region has a high concentration impurity region and a first low concentration impurity region provided around the high concentration impurity region, comprising steps of:

• a step for forming a channel stopper region of a first conduction type in the outer circumference of the formation region of the second field-effect transistor;
• a step for forming a second low concentration impurity region of a second conduction type in a region sectioned by the channel stopper region;
• a step for forming an element isolation film on the channel stopper region, the second low concentration impurity region, and the outer circumference surface of the formation region of the first field-effect transistor;
• a step for forming a common conductive film, in the first field-effect transistor formation region and the second field-effect transistor formation region, on gate insulating films corresponding to the respective transistors;
• a step for forming a gate electrode of the first field-effect transistor and a gate electrode of the second field-effect transistor by fabricating the common conductive film;
• a step for forming a source region of the second conduction type and a drain region of the second conduction type of the second field-effect transistor in a region sectioned by the second low concentration impurity region;
• and
• a step for forming the source region and the drain region of the first field-effect transistor in the first field-effect transistor formation region.