Oxalic acid was investigated as a complexing agent in H 2 O 2 -based slurries for chemical mechanical planarization (CMP) of Cu. At pH ∼ 1.5 , oxalic acid acts as an inhibiting agent by forming an easily abraded soft bluish film on the copper surface. The high removal rate and low dissolution rates make it a desirable complexing agent, except for the strongly acidic pH condition. In the pH range 2.0-6.0, oxalic acid etches copper with the maximum dissolution rate occurring at pH ∼ 3.0 . Cu removal rates and some electrochemical measurements that shed more light on these results are presented.
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Gorantla et al. (2005) studied this question.
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