| 摘要 |
PURPOSE: To secure flatness of a hole and an insulating layer, without decrease of a filler by overetching a 1st metallic substance, so as to remove a residue of a metallic substance present on an unmasked surface. CONSTITUTION: A tungsten peak of a plug 1, which is coplanar with the surface of an insulating layer 2, is completely masked with a cap 5 of resist. After this masking, etching conditions is corrected more preferably over operation under conditions similar to precedent etching-back conditions for decreasing the anisotropy of etching, thereby over-etching a tungsten residue in an RIE plasma, while increasing the selectivity of an insulating substance (oxide) forming a separate layer 2. For this purpose, a 2nd masked etching-back process of tungsten filling for removing the residue is performed in a mixture of F6 , Cl2 , and Ar and/or under a pressure lower than the 1st etching-back step.
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