| 摘要 |
PURPOSE:To realize ultraminiaturization of elements and high density integration by the oxide film separation method where the invasion into a mound or element region of field oxide film is prevented or suppressed. CONSTITUTION:A thin silicon nitride film 6 is formed on a silicon substrate 5 by the thermal nitriding method and an oxide film 7, a nitride film 8 and an oxide film 9 are respectively caused to grow on said film by the CVD method. Next, the oxide film 9 is selectively removed from the area other than the element forming region by the photo etching method. Then, thermal oxidation is carried out to form an oxide film 10 in the thickness of 1.5mum. After removing the oxide film 10 with a fluoric acid solution, an oxide film 11 is formed on the field region by the thermal oxidation method and thereafter a nitride film 12 is formed by the CVD method. Next, the nitride film 12 is selectively removed by the anisotropic dry etching and the nitride film 12 is left only at the area just under the nitride film 8. Thermal oxidation is carried out again to form the field oxide film 13 in the thickness of 1.5mum. Finally, the remaining nitride films 8, 12', oxide film 7 and thermal nitride film 6 are removed, thereby forming the oxide film separating region where there is no bird's beak, bird's head having flat surface. |
