Factors influencing open circuit decomposition behavior of sulfur-containing additive component used in Cu plating for advanced interconnect metallization
Accelerated decomposition of organic additives during open circuit condition was observed only when both copper wire and oxygen are present in the copper sulfate solution. The data suggest that the accelerating mercapto species could form a complex with cuprous ions from copper anode in the plating solution. The copper complexes formed then undergo oxidation reaction and lose its original electrochemical activity by introducing byproducts. Adsorption behavior of various chemical components in the plating solution on the copper anode surface was found to have a significant influence on the sulfur-containing brightening agent degradation rate. The degradation mechanisms attributed to the interactions among different chemical components are also addressed and discussed.
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