Effects of polishing parameters on surface quality in sapphire double-sided CMP

Abstract

To reveal the influence of polishing process parameters on the surface quality of sapphire after double-sided chemical mechanical polishing (CMP), the orthogonal test of sapphire wafer double-sided CMP was carried out by YH2M77110 high-precision vertical double-sided grinding/polishing machine. The effects of polishing parameters, such as polishing pressure(p), polishing carrier rotation speed(vr), and polishing time(t), were investigated regarding their effects on material removal rate (MRR), surface morphology, surface roughness (SR) and subsurface damage (SSD) depth. The experimental results showed that p and vr have the similar and significant positive correlation effects on the MRR and the SSD depth. However, as the increase of p and vr, the SR tends to decrease first and then increase. Prolonging t can effectively reduce the SR and the SSD depth but has a minor positive correlation effect on the MRR. The orthogonal experiment result optimization method based on weight matrix is used to obtain the influence degree of each factor on the orthogonal test index value. The set of optimal process parameter combinations are p = 35.37kPa, vr = 30r/min, t = 50min, which presented a higher MRR, lower SR and SSD depth. The quality and efficiency of sapphire double-sided CMP can be improved through parameter optimization according to this study.