Stability of H2O2 as an Oxidizer for Cu CMP

Chemical mechanical polishing is an essential process in the production of copper-based chips. On this work, the stability of hydrogen peroxide (H2O2) as an oxidizer of copper CMP slurry has been investigated. H2O2 is known as the most common oxidizer in copper CMP slurry. But H2O2 is so unstable that its stabilization is needed using as an oxidizer. As adding KOH as a pH buffering agent, stability of H2O2 decreased. However, H2O2 stability in slurry went up with putting in small amount of BTA as a film forming agent. There was no difference of H2O2 stability between pH buffering agents KOH and TMAH at similar pH value. Addition of H2O2 in slurry in advance of bead milling led to better stability than adding after bead milling. Adding phosphoric acid resulted in the higher stability. Using alumina C as an abrasive was good at stabilizing for H2O2.