Improvements of oxide-chemical mechanical polishing performances and aging effect of alumina and silica mixed abrasive slurries

Abstract

In this paper, in order to investigate the effects of agglomeration on the chemical mechanical polishing (CMP) performance of oxide layer using mixed abrasive slurry (MAS), we have studied an aging effect as a function of different slurry composition. Also, the effects of each slurry composition on the oxide CMP characteristics were investigated to obtain the higher removal rate and lower within-wafer non-uniformity (WIWNU). We prepared the various kinds of MAS. In order to save the cost of slurry, the original slurry was diluted by de-ionized water. Alumina (Al 2O 3) abrasives were added before and after annealing in the diluted silica slurry in order to promote the mechanical force of diluted slurry. As an experimental result, the CMP characteristics of 1:10 diluted silica slurry containing 1500 °C-annealed alumina abrasives of 0.5 wt% showed excellent removal rate and WIWNU. We think that it is due to the increase of mechanical strength of alumina abrasive particles after annealing. At the same time, we can anticipate the saving of high-cost CMP slurry for ULSI fabrication industry.