Mullite-based abrasives for chemical mechanical polishing of silicon carbide

Abstract

To tackle the issue of the low mechanical effect of traditional abrasives in polishing silicon carbide wafers, we successfully prepared mullite-based composite abrasive particles with a dense structure and favorable mechanical properties through the deposition of polymeric hydroxy-aluminum on the silica particle surface and the adjustment of the aluminum-to-silicon ratio. In this study, a range of characterization techniques, including electron microscopy, nitrogen adsorption-desorption measurements, and X-ray diffractometer, were employed to thoroughly examine the micro-morphology, surface characteristics, and lattice structures of the calcined samples. By analyzing the microstructural evolution in the particles and the variation pattern of their polishing effect, it is evident that the amplified mechanical effect resulting from the increased hardness of the abrasive particles, as the aluminum-to-silica ratio rises, greatly heightens the polishing rate, but also exacerbates surface unevenness. We hereby deduced that the improvement in the mechanical action of the abrasives during polishing mainly stems from the strengthening action of grain boundaries and the synergistic effect of structural densification. Notably, the synthesized abrasives can achieve an average removal rate of 0.93 μm/h, while ensuring surface planarization (Ra = 0.28 nm). Our findings provide enlightening perspectives for the preparation and performance evaluation of mullite-based particles, guiding their development and application.