The polishing methods for large area CVD diamond wafer

The mainstream polishing methods were reviewed in light of polycrystalline CVD diamond wafer with large area. The principles, equipment, and processes of the mainstream polishing methods were reviewed, and the processing characteristics of these methods were compared. The material removal rate (MRR), polishing rate (PR), and minimum surface roughness (Ra) obtained by each polishing method were summed up. The non-contact method has a relatively higher MRR than the contact method, while the contact method has a relatively smaller final roughness than the non-contact method. Two factors, K (K = ΔRa/Δm, ΔRa is the reduction of the surface roughness, Δm is the mass loss) and CI (CI = K/t, t is the total polishing time), were proposed to evaluate the influence of the polishing parameters on the polishing course in the contact polishing methods and to describe the feature of each polishing method, respectively. The variation of the K value indicated that the polishing load and the polishing plate speed did not always influence the polishing effect monotonically in every contact polishing method, and it should be optimized to obtain fine surface roughness with the tiny mass loss. The CI value showed that the non-contact polishing method possessed the feature of high roughness improvement with low mass loss in the unit polishing time. These results reveal how to move forward on the path to polishing large area polycrystalline CVD diamond wafer.