| 摘要 |
<p>PURPOSE:To improve the accuracy in position of an aligning mark for an active region of a semiconductor substrate, by forming a mark region oxide film simultaneously with the formation of an element isolating oxide film. CONSTITUTION:An SiO2 film 13 and a SiN film 14 are removed except those parts of the films present on a transistor forming region 15 and on the periphery of a mark region 16. The structure is then subjected to heat oxidation so that the portions of the substrate not covered with the SiO2 film 13 or with the SiN film 14 are oxidized to form an element isolating oxide film 17 and a mark region oxide film 18 both consisting of SiO2. The SiN film 14 is then removed with hot phosphoric acid, and the SiO2 film 13 is also removed by etching. All the surface except the periphery of the mark region 16 is covered with resist 19, and the semiconductor substrate 11 is etched to a predetermined depth with plasma of mixture gas consisting of CF4 and O2. In this manner, the substrate 11 in the mark region 16 is side etched with the mark region oxide film 18 used as a mask. The resist 19 is then removed. Thus, an aligning mark 20 composed of a mark portion 16a formed in the mark region 16 by transversely excavating the substrate and of the mark region oxide film 18 is completed.</p> |
