| 摘要 |
PURPOSE: To execute ion implantation for the formation of a channel-doped layer through a gate oxide film and prevent the deterioration of reliability as to a gate oxide film. CONSTITUTION: After forming a gate oxide film 3, a resist pattern 4 having an aperture at least in a channel region is formed by the lithography. Using the resist pattern 4 and a field oxide film 2 as the mask, boron is implanted with an energy of 15KeV at 4.2×10<12> /cm<2> into a substrate through the gate oxide film 3. Thereafter, the resist 4 is removed by the ashing process for cleaning of the silicon substrate. Next, the part 6 in the thickness of about 1nm at the surface of the gate oxide film is removed by the etching process using diluted fluoric acid coating fluoric acid and water at a ratio of 1:200 heated up to 30 deg.C.
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