The effects of slurry chemistry and film properties on the chemical-mechanical polishing (CMP) of three organosilicate glasses (SiOC) were used to develop an understanding of the removal mechanism during SiOC CMP. The SiOC removal 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 content decreased and the slurry pH increased. Film carbon content had the largest impact on CMP, due to its effect on film hydrophobicity and suppression 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. Surface and bulk chemical measurements show that chemical reactions with the slurry during CMP occur only at the polymer surface and do not penetrate into the bulk of the films. Experimental results are compared to the CMP of SiLK1 'silicon applications low-kappa microelectronics resin, a polymer with a comparable dielectric constant, and, to a lesser degree, with silicon dioxide. A mechanism for the CMP of SiOC films in silicon dioxide polishing slurries is proposed that includes the effects of slurry chemistry and film properties.