| 摘要 |
PURPOSE:To prevent the complication of a process by a method wherein ions aer implanted to the whole surface, one condution type region is coated with a mask and an impurity is introduced to the region, a previously formed conduc tion type is denied and the conduction type is changed into a reverse conduction type. CONSTITUTION:N<+> buried layers 2a, 2b and P<+> buried layers 3a, 3b are shaped to the surface of a P type sngle crystal silicon substrate 1, and an N type epitaxial layer 4 is formed on the whole surface. A mask is shaped selectively on the surface, and a P type impurity is diffused to form a P well region 5. A thick field insulating film 7, gate electrodes 12a, 12b and an N type diffusion layer 9 are formed, and N type impurity ions are implanted to the whole surface in the quantity of a dose of 1X10<13>/cm<2> and thermally treated. A partial region is coated with a mask, P type impurity ions are implated in the quantity of a dose of approximately 1.5X10<14>/cm<2>, and N<-> is denired, thus forming P<-> type regions 10a, 14a. |
