Effect of Low Energy Argon Ions Etching on the 4H–SiCOI Composite Substrate Prepared by Crystal‐Ion‐Slicing Technique

4H–SiC single‐crystal film is transferred to SiO2/Si insulating substrate by crystal‐ion‐slicing technology to form silicon carbide‐on‐insulator composite substrate, and the composite substrate is etched by low energy Ar+ ions irradiation. The amorphous oxide layer and defect layer are found on the surface of the exfoliated SiC film by using transmission electron microscopy and energy‐dispersive spectroscopy. Scanning electron microscopy, atomic force microscopy, and Raman spectroscopy are used to characterize the thickness, roughness, and crystal quality of the exfoliated SiC film. The result shows that the thickness of the film decreases from 1.238 to 0.911 μm, and the root mean square roughness decreases from 1.408 to 0.635 nm. Raman spectra show that the crystal quality of the SiC film is improved after etching. Moreover, the oxidation layer and defect layer on the surface of the SiC film can be quickly etched by Ar+ ions irradiation.