Tribocorrosion Study of Copper During Chemical Mechanical Polishing in Potassium Periodate-Based Slurry

Abstract

Copper chemical mechanical polishing (CMP) in barrier layer slurries with periodate as oxidant has not been intensively studied. This work presents an investigation into copper tribocorrosion in potassium periodate-based slurries during CMP. The research focused on copper tribocorrosion behavior, the surface chemical and electrochemical reaction products, and the electrochemical mechanism during CMP. The copper surface film was characterized by Raman spectra experiments. Tribocorrosion tests combined with CMP chemical experiments were conducted to study the tribochemical behavior and wear-accelerated corrosion effect. The results show that copper corrosion is more severe in acid solutions than in alkaline conditions. The copper surface is mainly passivated with copper oxides, copper hydroxide, and copper iodide. Small amounts of copper iodate, copper periodate, and iodine could be detected under specific pH conditions. Abrasion could help to get a uniform passivation film on copper surface consisting of copper oxides, copper hydroxide, and copper iodide only. The material loss due to wear-accelerated corrosion during CMP was also investigated. The results show that under weakly alkaline conditions (pH 9 and pH 10), the wear-corrosion effect plays an important role in the total material loss due to corrosion. The wear-accelerated corrosion is mainly caused by the exposure of more cathodic reaction sites to the slurry for participation in the redox reaction and the local galvanic corrosion during the CMP process. The high wear corrosion proportion of the total corrosion (ΔI c/I cc) could help to obtain a better surface quality and desirable material removal rate during CMP.