Effect of chemicals and slurry particles on chemical mechamical polishing of polyimide

The purpose of this study was to investigate the effect of chemicals and pa rticles on chemical mechanical polishing (CMP) of polyimide (PI). The effec t of particle size and its surface area on both the removal rates and the s urface roughness was investigated as a function of the slurry content upon the addition of various chemicals. The optimal particle content was measure d for silica, ceria and alumina slurries in terms of the removal rate and s urface roughness. The removal rate was highest when deionized (DI)-water-ba sed alumina slurry was used. However, the greatest surface roughness was me asured when ceria slurry was used rather than alumina. Alkaline chemicals w ere added to the slurry to enhance the removal rates of PI during CMP. The addition of Tetramethyl Ammonium Hydroxide (TMAH) and Potassium Hydroxide ( KOH) to ceria slurry but not to alumina and silica slurries increased the r emoval rate significantly at higher pH values. The addition of ethylenediam ine and the presoaking of PI in hot DI water did not increase the removal r ate in alkaline-chemical-based slurries. The addition of surfactant resulte d in a decrease of the removal rate to half of that determined without the addition of surfactant.