Abstract
Single-crystal 4H-SiC is a typical third-generation semiconductor power-device material because of its excellent electronic and thermal properties. A novel polishing technique that combines plasma electrolytic processing and mechanical polishing (PEP-MP) was proposed in order to polish single-crystal 4H-SiC surfaces effectively. In the PEP-MP process, the single-crystal 4H-SiC surface is modified into a soft oxide layer, which is mainly made of SiO2 and a small amount of silicon oxycarbide by plasma electrolytic processing. Then, the modified oxide layer is easily removed by soft abrasives such as CeO2, whose hardness is much lower than that of single-crystal 4H-SiC. Finally a scratch-free and damage-free surface can be obtained. The hardness of the single-crystal 4H-SiC surface is greatly decreased from 2891.03 to 72.61 HV after plasma electrolytic processing. By scanning electron microscopy (SEM) and X-ray Photoelectron Spectroscopy (XPS) observation, the plasma electrolytic processing behaviors of single-crystal 4H-SiC are investigated. The scanning white light interferometer (SWLI) images of 4H-SiC surface processed by PEP-MP for 30 s shows that an ultra-smooth surface is obtained and the surface roughness decreased from Sz 607 nm, Ra 64.5 nm to Sz 60.1 nm, Ra 8.1 nm and the material removal rate (MRR) of PEP-MP is about 21.8 μm/h.
Highlights
The surface roughness of the single-crystal 4H-SiC substrate seriously affects the performance of the power devices; the electric breakdown field intensity and charge to breakdown have been confirmed to increase with decreasing surface roughness, and a decrease in surface roughness was confirmed to increase the transconductance of a metal oxide semiconductor (MOS) transistor [1]
plasma electrolytic polishing (PEPo) is a special electrochemical polishing process used in precision polishing of metal parts at present under the condition of high voltage and environmental saline solution, which can make the surface of the metal part smooth and shiny and obtain a better corrosion resistance with higher material removal rate (MRR) [19,20,21]
This paper proposes a novel polishing technology named plasma electrolytic processing and mechanical polishing (PEP-MP) for single-crystal 4H-SiC polishing, in which the single-crystal 4H-SiC surface is modified into a soft oxide layer by plasma electrolytic processing; the oxide layer is mechanically removed by soft abrasive efficiently
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Deng et al [14] developed electrochemical mechanical polishing based on Ceria (CeO2 ) slurry to process a diamond-abrasive-polished surface of single-crystal. The recent research focuses on developing a precision polishing technology for single-crystal 4H-SiC to achieve higher MRR with required surface roughness. PEPo is a special electrochemical polishing process used in precision polishing of metal parts at present under the condition of high voltage and environmental saline solution, which can make the surface of the metal part smooth and shiny and obtain a better corrosion resistance with higher MRR [19,20,21]. Since the CeO2 abrasive is softer compared with SiC, the polishing process only removes the oxide layer without introducing any scratches and surface damages.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
