Chemical mechanical polishing (CMP) of bis-benzocyclobutene(TM,a) (BCB) and "silicon-application low-kappa" (SiLK(TM,a)) polymers in slurries commonly used for copper removal is studied. Material removal rates were determined for a variety of conditions, with surface roughness measured after polishing by atomic force microscopy. BCB exhibited removal rates of 10-50 nm/min and roughness of 0.5 -1.4 nm, while SiLK exhibited removal rates of 20-300 nm/min and roughness of 0.8 to 2.0 nm. X-ray photoelectron spectroscopy measurements on BCB showed an increase in surface oxygen to 14% after CMP, compared to a bulk concentration of 3.5%. Similarly, SiLK surface oxygen increased to 12% after CR IP, compared to near zero in the bulk. A physically based model for polymer CMP is proposed. The model describes chemical and surfactant diffusion, surfactant adsorption, surface reactions, and surface abrasion during polishing. Two cases for the chemical action of the slurries are described by two different removal mechanisms. Case I describes slurry that does not react with polymer structural bonds. Instead, slurry oxidizes the polymer surface layer, deterring physical damage and CMP removal. Case II describes slurry that reacts with polymer structural bonds, forming a weakened layer that is removed rapidly during CMP.