| 摘要 |
PURPOSE:To prevent disconnection of wiring at the step parts and reduction of gate withstand voltage and to suppress formation of bird beak and unevenness of threshold voltage to enhance reliability of a semiconductor device by a method wherein the selective oxidation method is improved. CONSTITUTION:A silicon layer 32 is made to grow epitaxially on a sapphire substrate 31, and an SiO2 film 33, an Si3N4 film 34 are accumulated thereon by the CVD method. After patterning of the SiO2 film 33, the Si3N4 film 34 is performed by the photoethcing method, anisotropic ethcing is performed making thereof as a mask, and the silicon layer at the field part is removed partially in the direction of film thickness. Then ion implantation of oxygen is performed to form oxygen implanted layers 32' at the field region. The heat-treatment is performed next making the Si3N4 film 34 as an oxidation resistive mask to form field oxide films 322. Accordingly the surface of the element region 321 and the surface of the field oxide films 322 are formed nearly flatly. |
