Preparation and Application of Sol-Gel Polishing Pad for Polishing CVD Single Crystal Diamond at High Speed

A new polishing pad based on the sol-gel (SG) technique is fabricated and can polish the single crystal diamond (SCD) substrate at high speed. In this work, the base material, fillers, and coating height of the polishing pad are selected. Pressed polymer fiber is used as the base material, talcum powder is chosen as filler, and the coating height of the gel formulation system on the surface of the base material is between 20 and 40 $\mu \text{m}$ . The surface morphology of SCD substrate was observed with a 3D optical surface profiler. The surface roughness decreased from 78.024 nm to 6.126 nm in 2 h and the material removal rate of the SCD (100) was about 135 nm/h. The Raman spectroscopy result shows that there was phase transformation on the surface of the SCD substrate after polishing. The material removal mechanism was proposed based on the result. During the scratch of the diamond abrasive, the diamond on the surface of the SCD substrate was transformed into amorphous carbon. Then the amorphous carbon was removed mechanically. The new gel polishing pad can polish the SCD substrate with high efficiency.