Investigation of thermal effects in bulk oxide chemical mechanical polishing

Bulk oxide polishing occupies a substantial portion of time to achieve surface planarization in semiconductor manufacturing. Recently, thermal management has emerged as a critical issue in the polishing process. Fundamental research on thermal effects in oxide film polishing is essential for optimizing both the thermal management system and the polishing process itself. Experiments indicate that friction force, significantly influenced by wafer and retainer ring pressures as well as slurry species, plays a major role in determining polishing temperature, more so than slurry flow rate. An important finding is the temperature-dependent behavior of slurry particles, which generally reduce in size and concentrate more at higher temperatures, with aggregation starting at around 80 degrees C. High-temperature slurry deteriorated pad properties but enhance oxide film surface hydrolyzation. During a 60-s polishing process, the slurry temperature exhibited the maximum removal rate at 60 degrees C for fumed silica polishing, while for calcined ceria, the highest removal rate was observed at 20 degrees C. Pad B at ambient temperature, having similar hardness to Pad A at 60 degrees C, reduced the oxide film removal rate by 31.82 % for fumed silica and 40.94 % for calcined ceria. This indicates that pad hardness has a more pronounced effect on polishing with calcined ceria slurry.