Effect of Using High-Pressure Gas Atmosphere with UV Photocatalysis on the CMP Characteristics of a 4H-SiC Substrate

The objective of this study was to realize high-efficiency and high-quality chemical mechanical polishing (CMP) of a silicon carbide (SiC) substrate. Consequently, the effect of a gas atmosphere on the CMP characteristics of a SiC substrate was investigated. The experimental results show that increasing the partial pressure of oxygen (O 2 ) in the atmosphere to 300 kPa led to an over 2-fold increase in the material removal rates (MRRs) of the Si and carbon (C) faces compared to an open-air atmosphere. White light interference microscopy, energy-dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS) were used to analyze the face morphology and surface elements after processing. Si face atoms were more difficult to oxidize than C face atoms, resulting in a low MRR of the Si face after CMP. The MRR of the Si face was improved by using an ultraviolet (UV) photocatalysis reaction in the high-pressure O 2 atmosphere. Excitation of O 2 molecules in the slurry into HO 2 • with a stronger oxidation capability promoted the chemical reaction at the solid-liquid interface. The processing mechanism was elucidated.