Aqueous stability diagrams and electrochemical measurements were used to study the behavior of copper in hydroxylamine (NH_2OH) solutions at different pH values. The diagrams indicated the presence of a stability region for the copper-hydroxylamine complexes centered around pH 6. Electrochemical experiments (open circuit potential measurements and potentiodynamic polarization) confirmed the existence of this region. The dissolution rate of copper in hydroxylamine solutions was found to be strongly dependent on pH. The dissolution was highest in the pH range where the copper-hydroxylamine complexes are stable. The implications of these results for the chemical mechanical polishing of copper are discussed.
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