| 摘要 |
PURPOSE:To prevent etching from scattering by a method wherein an etching mask with its higher portion wider than its lower portion is used in the formation of a trench, the trench is filled up with an insulating material, an etching- back process is accomplished to continue until the mask is exposed, and the mask is subjected to a selective etching process. CONSTITUTION:A thermal oxide film 6, polycrystalline silicon film 201, tantalum silicide film 202, and oxide film 203 are deposited on a semiconductor substrate 1, in that order, for the formation of etching masks 21-23. This process is so accomplished that the masks 21-23 present a cross section with its upper portion wider than its lower portion. The substrate 1 is subjected to anisotropic etching that is accomplished vertically so that the shape of the oxide film mask 203 may be transferred into the substrate 1. Formation of a trench follows, an insulating material is deposited, and then etching-back is performed, for the production of buried insulating elements 41-43. The etching-back continues until the exposure of the etching masks 21-23, which are next removed. In this way, the substrate 1 inside the trench is prevented from exposure due to the scattering of etching.
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