| 摘要 |
PURPOSE:To obtain an oxidized film having a flat surface by a method wherein all of SiO2 alone is removed after completion of the 1st selective oxidation, a groove is made in exact depth in an Si substrate and then oxidation is applied again with the 1st Si3N4 mask being used. CONSTITUTION:An SiO2 film 12 on the Si substrate 11 is oxidized with the Si3N4 mask 13 being applied and thereby the SiO2 film 14 is formed. The film 14 intrudes deep into the Si substrate by the half of its thickness, approximately, and the depth is decided correctly according to the thickness of the film 14. When the SiO2 14 is removed through etching selectively, the groove 15 is obtained. Then an SiO2 film 16 is provided again through selective oxidation under the same condition and the Si3N4 mask is removed. By this constitution, the surface can be made flat simply and with excellent precision and thus the usual etching of the surface of the Si substrate for levelling becomes unnecessary. |
