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In order to achieve high throughput Cu-CMP compatible with low step heights in 32nm Node copper interconnect technologies and beyond, we believe it is crucial a passivation layer on the Cu surface in the slurry during the CMP process. We show that the formation of a passivation layer which achieves good planarization with high Cu removal rate can be controlled by selecting the rest potential of the Cu ions in the slurry.

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In the chemical mechanical polishing (CMP) process, we have discovered that the Cu etching rate can be enhanced without affecting the Cu slurry's pH by adding a small amount of the sulfur compounds MPS and Na 2 S 2 O 3 . Adding the sulfur compounds to the H 2 O 2 slurry results in an increment in the oxidation reduction potential (ORP). The electrochemical model (mixed potential) showed that the ORP increment leads to enhancement of the Cu oxidizing reaction. Because XPS and Raman analysis of the Cu surface revealed that the Cu etching rate in CMP is limited by the Cu oxidizing reaction, we concluded that the Cu etching rate is enhanced by the addition of sulfur compounds to the Cu oxidizing reaction to increase the ORP increment.