Chemical-mechanical polishing of SiOC organosilicate glasses: the effect of film carbon content

The effects of slurry chemistry and film properties on the chemical-mechani cal polishing (CMP) of three organosilicate glasses (SiOC) were used to dev elop an understanding of the removal mechanism during SiOC CMP. The SiOC re moval rate varied from 40 to 80 nm/min in slurries commonly used to polish silicon dioxide, with the removal rate increasing as the SiOC film carbon c ontent decreased and the slurry pH increased. Film carbon content had the l argest impact on CMP, due to its effect on film hydrophobicity and suppress ion of slurry chemical attack. SiOC surface roughness after CMP was as low as 0.15 nm at a slurry pH of 10.8 and 0.41 nm at a slurry pH of 6.0. Surfac e and bulk chemical measurements show that chemical reactions with the slur ry during CMP occur only at the polymer surface and do not penetrate into t he bulk of the films. Experimental results are compared to the CMP of SiLK1 'silicon applications low-kappa microelectronics resin, a polymer with a c omparable dielectric constant, and, to a lesser degree, with silicon dioxid e. A mechanism for the CMP of SiOC films in silicon dioxide polishing slurr ies is proposed that includes the effects of slurry chemistry and film prop erties. (C) 2001 Elsevier Science B.V. All rights reserved.