Pad Conditioning and Scale-up Issues Between 200 and 300 mm Polishing

摘要

Polish rate reduction and significant uniformity excursions were observed when polishing 300 mm wafers with fumed silica slurry using pad conditioners that were optimized for 200 mm polishing. Uniformity issues could be rectified with more aggressive conditioning, but in most cases the polish rate could not be fully recovered over the range of conditioning aggressiveness studied. Significantly higher removal rates, compared to fumed slurry, were observed under similar process conditions when colloidal slurry was used in 300 mm polishing. While the magnitude of some of these responses are likely due to relative slurry flow rate differences between the 200 and 300 mm platforms, these results are consistent with a pad asperity wear mechanism contributing to the reduced polish rates on the 300 mm platform. Inspection of the pad surface statistics from both 200 and 300 mm polishing indicates that the degree of pad surface wear and the resulting damage to the surface asperity structure is greater on 300 mm.