Highly reliable chemical-mechanical polishing process for organic low-k methylsilsesquioxane

In this work, chemical-mechanical polishing (CMP) of the organic polymer, m ethylsilsesquioxane (MSQ), has been investigated. For conventional silicate -based slurry, the CMP removal rate of MSQ is low and many scratches are fo rmed at the surface. Moreover, the dielectric properties of a post-CMP MSQ film are degraded in comparison to the as-cured MSQ. We have proposed a rel iable process for the CMP of MSQ which includes a slurry of additive and a post-CMP NH3 plasma treatment. Experimental results show that the modified slurry provides a high polishing rate and uniform surface topography. In ad dition, the NH3 plasma process can form a thin nitrogen-containing layer on the post-CMP MSQ surface, which enhances the resistance to moisture absorp tion and copper diffusion. (C) 2001 American Vacuum Society.