Diamond films by CVD and high rate polishing at low temperature with partially molten Ce-Fe alloy

A new effective technique for polishing free-standing diamond films at low temperature is proposed. The alloys (Ce-7%Fe) were smelted with rare earth metal Ce and transition metal Fe of high carbon solubility. Using the alloy, the CVD diamond films were thermal-chemically polished. The experimental results indicate that the diamond films could be polished by Ce-7%Fe at 592°C, even 200°C lower than the temperature used in reported rare earth polishing process. The value of Ra is decreased from 5.95 μm to 0.69 μm after polished at 680°C for 3 hours with a high removal rate of 30 μm/h. SEM results show that the polished diamond films become much smoother. Furthermore, the Raman spectra analyses show that the surface of diamond films have not been contaminated after polishing.