| 摘要 |
PURPOSE:To make mass productivity excellent, to make the crystallinity of a single crystal silicon layer same as that of a single crystal silicon substrate and to make the insulating property of an element isolating region same as that of a silicon thermal oxide film, by forming a tapered element isolating groove, downwardly wider, in the element isolating region part of the single crystal silicon substrate so that the groove reaches the lower surface of an oxygen ion implanted layer from the surface of the substrate. CONSTITUTION:Oxygen ions are implanted 23 in the entire surface of a thermal oxide film 22, which is formed on a single crystal silicon substrate 21 with an accelerating voltage. An oxygen-ion implanted layer 24 and a single crystal silicon layer 25 are formed. Then a silicon nitride film 26 and a silicon oxide film 27 are formed on the film 22. The film 27 is coated with resist 28. The resist 28 is made to remain only at a transistor forming region 29. With the resist 28 as a mask, the films 27, 26 and 22 are made to remain only at the region part 29 and removed from an element isolating region part 30. After the resist 29 is removed, an element isolating groove 31 is formed in the substrate 21 at the element isolating region part 30 with the film 27 as a mask so that the groove reaches the lower surface of the layer 24 from the surface of the substrate.
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