| 摘要 |
A Si3N4 film is formed as a protective film over a BPSG film. The film thickness of the Si3N4 film is determined by the relation of the working rate of the BPSG film to the working rate of the Si3N4 film and the height of the convex portions on the surface of the BPSG film. The Si3N4 film formed over the convex portions is then removed over areas slightly larger than the convex portions such that the film does not overlie the convex portions. When the silicon substrate is subsequently polished through the use of colloidal silica slurry, the convex portions can be selectively removed by polishing while the surface of the BPSG film is protected by the Si3N4 film.
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