Copper dissolution and chemical-mechanical polishing in acidic media

Chemical-mechanical polishing (CMP) of copper was conducted using ferric nitrate (Fe(NO3)(3)) as an etchant and benzotriazole (BTA) as an inhibitor and alumina particles as the abrasives. Copper polish rate decreases dramatically with BTA concentration. The addition of BTA to Fe(NO3)(3) slurries increases the polish efficiency by reducing the copper dissolution rate. The copper CMP process in the acidic media used here is primarily mechanical and pure chemical etching during copper CMP is minimal. Copper polish rates were also measured in the presence of an external applied potential in the presence and absence of BTA. A possible explanation for the observed variation of the copper polish rates is that some of the surface mechanical properties of copper are altered by the applied potential in the presence of the reactive chemicals.