Synergistic effect of aminosilane and K2CO3 on improving Chemical Mechanical Polishing performance of SiO2 dielectric layer

Abstract

Chemical Mechanical Polishing (CMP) is a widely used surface treatment process in integrated circuit manufacturing for global planarization of the surface layers of various materials. The CMP slurry is regarded as one of the key determinants of planarization performance, considering the synergistic effect of its abrasive and other chemical components. As the component size is decreased to the molecular or even atomic scale, ways to achieve a high material removal rate of the SiO2 dielectric layer while maintaining high surface topography quality have become a challenge for the integrated circuit manufacturing industry. In this work, the synergistic effect of aminosilane and K2CO3 in the SiO2 CMP process was identified. A material removal rate of 248 nm/min and surface roughness of 0.374 nm was achieved under a pH of 11, SiO2 abrasive of 12 wt%, K2CO3 concentration of 0.12 M, and 3-aminopropyltriethoxysilane (APTES) concentration of 60 ppm. Through X-ray photoelectron spectroscopy (XPS), it was found that APTES can be adsorbed on the surface of SiO2 film through chemical bonding. Further, it was proved by fourier infrared spectroscopy (FTIR) that APTES could be combined with abrasive particles and coated on the surface of abrasive to realize the modification. The changes in particle size and zeta potential of the slurry were measured with a laser particle size analyzer. The studies suggested that under the influence of K2CO3, the hydration reaction on the SiO2 surface was intensified, the chemical bonding between APTES and the silanol (Si–OH) dangling bond on both surface of abrasive and SiO2 film was established, which enhanced the chemical reaction on the wafer surface. Finally, a material removal model of SiO2, characterized by the synergistic effect of APTES and K2CO3 was proposed based on the study.