Fig. 1. Tetrahedral molecular structure of fused silica^[21]

Fig. 2. TEM maps of three commonly used abrasive particles^[28]. (a) SiO₂ abrasive particles; (b) Al₂O₃ abrasive particles;(c) CeO₂ abrasive particles

Fig. 3. Commercial optical pitch polishing pad

Fig. 4. Schematics of the contact between a wafer, an abrasive particle, and different texture pads^[37]. (a) Soft pad; (b) hard pad

Fig. 5. Schematic of the micro-contact between a pad, an abrasive particle, and a wafer^[39]

Fig. 6. Schematic of fluid hydrodynamics in polishing^[43]

Fig. 7. Distributions of hydrodynamic pressure and solid contact pressure^[50].(a) Hydrodynamic pressure; (b) solid contact pressure

Fig. 8. Fluid pressure signal and its relationship with the physical position^[51]

Fig. 9. Three fracture mechanisms for the chemical tooth model^[53].Comparision of bond strength between M—O and Si—O: (a) The former is smaller than the latter; (b) the former is larger than the latter; (c) the former is smaller than the latter

Fig. 10. AFM images of friction scars on Si(100) surfaces after cyclic friction in various relative humidity^[55]

Fig. 11. Relative intensity of relative chemical components in the region of original surface, wear scar, and wear debris on Si(100) surface^[55]

Fig. 12. CMP removal model of sapphire wafer^[56]

Fig. 13. Relationship between removal volume in moles of Si tips and those of corresponding SiO₂ films^[57]

Fig. 14. Microscopic model proposed for removal mechanism between Si and SiO2[59]

Fig. 15. Schematic showing the interaction at the wear interface between Si and SiO₂ due to a variation of solution pH^[58]

Fig. 16. In situ characterizations in a liquid environment^[60]. (a) SEM image of AFM tip prior to the in situ study; (b) AFM image of the sapphire wafer surface after the CMP fine polishing process as the initial state for the in situ study; (c) time-dependent surface roughness values of the wafer surface with different set-point values during the in situ study; (d) evolution of wafer surface morphology during the in situ study; (e) SEM image of the AFM tip after the in situ study; (f) AFM image of a processing area after the in situ study; (g) larger AFM image from processed area in Fig.16(f); (h) section height line taken from Fig.16(g)

Fig. 17. IR spectra of fused silica before and after 6 h polishing by acid and alkaline SiO₂ slurries^[61]