A method of chemical mechanical polishing that polishes a substrate by abrading a target material formed on the substrate with a polishing pad containing a slurry includes setting a polishing end time, at which time a predetermined thickness of the target material will have been removed from the substrate by polishing, polishing the substrate to remove the predetermined thickness of the target material, and increasing a level of byproduct contamination in the polishing pad to decrease a polishing rate, while polishing the substrate, so that the polishing rate decreases to approximately zero at the polishing end time.