High breakdown voltage semiconductor device and fabrication method of the same

A method of fabricating a high breakdown voltage semiconductor device formed using an SOI substrate comprising a support substrate, an insulating film formed on the support substrate, and an active layer formed on the insulating film, the method comprising the steps of:

• forming a first conductive type well region on the active layer;
• forming a second conductive type drain offset region on the active layer and apart from the well region;
• forming a second conductive type source region on the well region;
• forming a second conductive type drain region on the drain offset region;
• forming a gate insulating film in at least a region interposed between the source region and the drain offset region of the active layer;
• and
• forming an electrode on the gate insulating film,
• wherein the method further comprises forming a first conductive type deep well region by implanting first conductive type impurity with high energy, under the drain offset region of the active layer, and
• a concentration peak of the first conductive type impurity introduced for formation of the deep well region is located deeper than a concentration peak of a second conductive type impurity introduced for formation of the drain offset region.