Effect of UV-illumination on electrochemical anodic oxidation of SiC

Abstract

Introducing an external energy field to force the oxidation of SiC is considered as an effective way to address the current challenge of chemical mechanical polishing (CMP) for SiC fabrication. In this study, we firstly compared several reported oxidation methods that have been used in different CMP-based techniques for SiC substrate, and demonstrated that the electrochemical (EC) and photoelectrochemical (PEC) anodic oxidations had significant advancement of the oxidation efficiency. Further comparison between EC and PEC revealed that PEC produced more uniform and smoother oxide layers in similar oxidation rates, while applied voltage and light intensity played a composing role in controlling the outcome. The quasi-in situ (photo)electrochemical atomic force microscopy analysis on the nanoindentation introduced artificial defects unraveled that, holes were prone to gather around the defective regions and resulted in faster oxidation rate, while the PEC can suppress such selective oxidation. These results suggest that the introduction of light has the potential to address the long-standing challenge of poor surface quality in electrochemical mechanical polishing (ECMP), not only for SiC but for various different semiconductor materials, and provide practical guidance for the industry to enhance PECMP performance on SiC and other hard and chemical inert semiconductor materials through optimizing oxidation processes.