Ceria-Based Abrasive Composite to Improve MRR of SiO2 in 3D-NAND

Abstract

The effect of ceria abrasive compound with zirconia and silica on polishing performance of SiO2 dielectric was studied. The results show that adding zirconia and silica to the ceria slurry can improve the polishing performance of SiO2 dielectric. When the mass ratio of ceria and zirconia is 4:3, the material removal rate (MRR) of SiO2 dielectric is increased to 218.6 nm min−1 at pH 3. Meanwhile, under the same pH, when the ratio of ceria to silica is 2:1, the MRR of SiO2 dielectric is 228.8 nm min−1. But the MRR reaches the highest at pH 5, the MRR of SiO2 dielectric reached 477.7 nm min−1 after the combination of ceria and zirconia, and 538.2 nm min−1 after the composite of ceria and silica. With the increase of the average particle size of silica, the MRR of SiO2 dielectric increases gradually. When the silica particle size is 80 nm, the MRR of SiO2 dielectric is the highest of 538.2 nm min−1. When using PL-3 instead of alkaline silica to verify the polishing rate of TEOS dielectric and Si3N4, the removal rate of TEOS dielectric reached 1080.6 nm min−1, the removal rate of Si3N4 was only 91.9 nm min−1, and the removal rate selectivity was 11.75:1. At the same time, the surface roughness of SiO2 dielectric is also decreased after the abrasive mixture.