Synthesis of Al2O3@MnO2 composite abrasives and their chemical mechanical polishing performance on silicon carbide (SiC)

Abstract

The effectiveness of silicon carbide (SiC) planarization mostly relies on the chemical and mechanical effects during chemical mechanical polishing (CMP). Nevertheless, the alumina (Al2O3) abrasive only provides a mechanical effect and is incapable of achieving a high-efficiency polishing of SiC. To address this issue, a series of novel Al2O3@MnO2 composite abrasives were prepared by encapsulating varying amounts of manganese dioxide (MnO2) on Al2O3 abrasive, and the polishing performance on SiC wafers was evaluated. The X-ray diffraction (XRD) and scanning electron microscope (SEM) images, along with the size and zeta potential data, show that MnO2 is successfully coated on the surface of Al2O3, and the dispersion of Al2O3@MnO2 composite abrasive is significantly improved when compared with the pure Al2O3. Furthermore, the CMP experiment and surface profile analysis demonstrate that the material removal rate (MRR) can reach a maximum value of 640.47 nm/h when using a 0.05 wt% MnO2-coated Al2O3 composite abrasive, which is 76 % higher than that of traditional Al2O3 abrasive. Furthermore, the average surface roughness (Sa, arithmetic mean height) of SiC is reduced to 0.73 nm. X-ray photoelectron spectroscopy results reveal that the surface of SiC is oxidized and forms a chemical bond known as Mn–O–Si after CMP. The results of the friction coefficient test and contact angle test indicate that slurries containing composite abrasive have exceptional wettability and a higher friction coefficient. Under the synergistic chemical and mechanical effects, SiC is oxidized to soft oxide and then removed circularly to reach excellent flatness.