Poly(acrylic acid)-Containing Ceria Slurries for Shallow Trench Isolation Chemical Mechanical Polishing: Colloidal Stability, Planarization Efficiency, and Selectivity

This study reports poly(acrylic acid) (PAA)-containing ceria slurries for shallow trench isolation (STI) chemical mechanical polishing (CMP). HNU15 ceria nanoparticles were prepared by precipitation at room temperature. PAA was synthesized by aqueous free-radical polymerization, characterized by gel permeation chromatography and Fourier-transform infrared spectroscopy, and used as the polymeric dispersant in both HNU15 and commercial HC10 slurries. The primary-particle sizes determined by TEM were 12.2 ± 1.5 nm for HNU15 and 14.6 ± 1.4 nm for HC10, whereas the crystallite sizes calculated from XRD were 10.2 nm and 8.7 nm, respectively. HNU15 showed a higher BET surface area and Ce3+ fraction than HC10, indicating measurable differences in textural properties and surface chemical states. After 5 h of milling, the HNU15 and HC10 slurries exhibited DLS d50 values of 111 nm and 122 nm and zeta potentials of −53.60 mV and −49.40 mV, respectively. Both slurries maintained generally stable colloidal properties during four weeks of storage at 25 °C and 60 °C. Under the laboratory CMP conditions, HNU15 slurry exhibited an HDP-SiO2 removal rate of 114.4 Å min−1, an HDP-SiO2-to-Si3N4 selectivity of 8.0, and lower post-polishing roughness than HC10. These results support the use of the PAA-containing HNU15 slurry for STI CMP applications.