| 摘要 |
PURPOSE:To obtain a device having high density through a process having excellent yield by implanting ions to a substrate in order to control the threshold voltage of a transistor and forming a gate insulating film. CONSTITUTION:A double layer film 22 consisting of an SiO2 film and an Si3N4 film is shaped selectively onto the main plane of a P-type Si substrate 11, and a B<+>-ion implanting region 23 for controlling the threshold voltage of a field region is formed to an opening section in the film 22. The substrate 11 is oxidized while using the double layer film 22 as a mask material to oxidation to selectively shape a field oxide film 13. The Si3N4 film in the double layer film 22 is removed, and a B<+> or P<+>-ion implanting region 24 for controlling the threshold voltage of a MOS type Tr is formed selectively through the residual SiO2 film. The SiO2 film is removed, and a gate oxide film 25 is shaped. Since the gate oxide film 25 is formed after ion implantation in the process, there is no contamination in a photo-etching process and an ion implantation process and no pin hole is generated. Polycrystalline Si films 27 are shaped selectively, and a gate electrode 27a and wirings 27b, 27c are formed. |
