Novel highly-efficient and dress-free polishing technique with plasma-assisted surface modification and dressing

Abstract Slurry is widely used in polishing difficult-to-machine materials. However, it is accompanied with some issues, such as the agglomeration of abrasives and high disposal cost. Although using fixed abrasive grains instead of slurry can solve these issues, the problems of wear and of loading fixed abrasive grinding stones, which result in decrease of material removal rate (MRR), also need to be solved. Many researches have been conducted on the self-sharpening of fixed abrasive grinding stones. However, the self-sharpening of grinding stones is not efficient with ultra-low polishing pressure, which is not large enough to break bonds so as to expose new abrasives. In this study, a novel dress-free dry polishing process was proposed, where it combines plasma-assisted polishing and plasma-assisted dressing using Ar-based CF4 plasma and a vitrified-bonded grinding stone. Polishing experiments were conducted on sintered AlN wafer. Also, as the main component of vitrified bond materials, silica was etched using CF4 plasma, which is equivalent to the continuous dressing of grinding stone surfaces. Since new abrasives could be constantly exposed, a high MRR was maintained. Thus, a dress-free high integrity polishing process was realized. Moreover, the CF4 plasma irradiation increased the MRR twice, as CF4 plasma can not only dress a grinding stone in real time but can also modify AlN to AlF3, which can easily be removed.