| 摘要 |
PURPOSE:To form a thick oxide film for element isolation without generating strains on a substrate Si and without the expansion of the thick oxide film in a transverse direction by a method wherein an Si oxide film of the thickness of several hundred Angstrom is thermally oxidized previously and then used under a vapor growing nitride film which serves the mask for oxidation. CONSTITUTION:The Si oxide film 202 of the thickness of several hundred Angstrom is formed on an Si substrate 201 by thermal oxidation as shown in the Fig. (a), and next the Si oxide film 202 is changed into an Si oxide film 203 which is applied to thermal nitriding by heat treatment in a atmosphere containing ammonia gas as shown in the Fig. (b). Then, the thermal nitride Si oxide film 203 which is selectively left and an Si nitride film 204 are formed as shown in the Fig. (c) by vapor-growing and then etching the Si nitride film, and finally the thick element isolating insulation film 205 is formed as shown in the Fig. (d) with said thermal nitride Si oxide film 203 and Si nitride film 204 as the oxidation mask. |
