Semiconductor device with an insulation double well and method of manufacturing the same

摘要

An object of the present invention is to manufacture a semiconductor device excellent in withstand-voltage property of each element formed in a peripheral element region portion, without incurring complexity of a manufacturing process. Impurity ions are injected into a substrate so as to form a first well portion and field oxide films for partitioning a substrate surface including the surface of the first well portion into a plurality of active regions. Further, the impurity ions are injected into the first well portion so as to form a second well portion having a plurality of active regions. Regions corresponding to the active regions on the second well portion are exposed and a mask for covering regions other than the above regions is formed. Ions are injected into the second well portion exposed from the mask under the action of energy transmitted through the field oxide films.