Chemical mechanical polishing slurry for tungsten

Abstract

A ferric nitrate-alumina based slurry useful for Chemical-Mechanical-Polishing of tungsten metallurgy 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 375 ml of a 9% wt alumina suspension, about 200 grams ferric nonahydrate, water to dilute to about 4.5 liters and enough 70% wt nitric acid to adjust the pH of the slurry to about 1.0 to 1.5.

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