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Etch-Back Planarization Technique for Multilevel Metallization

In order to realize multilevel interconnections of VLSIs, problems in the conventional etch-back planarization of silicon oxide film have been clarified through a detailed study. Also, a new etch-back planarization technique has been developed using silicon nitride films, which is able to form very smooth surfaces. An end point detection for the etch-back is also proposed. This planarization technique and a newly developed method of “via hole making” have been successfully applied to Al three-level interconnections with a 2µm design rule.