Chemical mechanical polishing slurry and method for polishing metal/oxide layers

Abstract

A ferric nitrate-alumina based slurry useful for Chemical-Mechanical-Polishing of tungsten metallurgy and silica based oxides on semiconductor substrates in which the suspension and stability of abrasive material in the slurry is essentially stable. The slurry formulation is balanced to provide low residue of foreign material after polishing and due to its reduced ferric nitrate concentration will be less corrosive than prior art slurries. The recipe for the slurry includes of a 30% wt silica suspension, about 800 ml of 40% by wt ferric nonahydrate and enough 70% wt nitric acid to adjust the pH of the slurry to about 1.2 to 1.4.

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