Coupled mechanical and chemical effects of slurry temperature in DETA-assisted silicon chemical mechanical planarization

Chemical mechanical planarization (CMP) is commonly employed to remove or reduce defective surface layers generated during wafer thinning, where micrometer-scale removal must be achieved while maintaining high surface quality. In this study, a slurry temperature control strategy was proposed for high-removal-rate silicon CMP by combining slurry heating with diethylenetriamine (DETA), a conventional hydrolysis-accelerating additive. In the DETA containing slurry, the Si material removal rate increased from 8779 to 13,297 Å/min with increasing slurry temperature while the surface roughness expressed as R a improved from 0.922 to 0.363 nm. To identify the origin of this improvement, the temperature effect was analyzed by separating the physical and chemical contributions. Pad surface topography and dynamic mechanical analysis showed that elevated temperature modified the pad surface morphology and reduced the storage and loss moduli, indicating thermally induced pad softening that may alter the real contact area and frictional behavior at the pad–wafer interface. Contact angle measurements, X-ray photoelectron spectroscopy, and nanoindentation analysis further revealed that elevated temperature promoted DETA assisted oxidation and hydroxylation, accompanied by a reduction in the apparent mechanical resistance of the chemically modified near-surface layer. These results suggest that slurry temperature control can serve as a practical process-control approach for high-rate Si CMP and provide a useful basis for backside Si polishing processes requiring micrometer-scale removal after wafer thinning.