The physical model of nanosecond laser ablation of semi-insulating 4H-SiC irradiated by KrF excimer laser with a wavelength of 248 nm was studied. The etching depth was tested by a stylus surface profiler. The morphology of the ablation pit and the thickness of the damaged layer were observed through scanning electron microscope. The phases at the laser irradiated surface were analyzed by Raman spectroscopy. In situ x-ray photoelectron spectroscopy was used to obtain component distribution of the damaged layer and a reasonable thermophysical model was constructed. The temperature distribution of the substrate after the laser irradiation was calculated according to this model. It was found that the etching depth had a linear relationship with the number of laser pulses and the thickness of the uniform damaged layer was independent of pulse number $(>10)$. The thickness of the ablated layer and the newly generated damaged layer are equivalent for each laser irradiation. The established laser ablation model deepens the understanding of physical process and mechanism of nanosecond laser etching of SiC and provides a theoretical guidance for laser processing of SiC.

• Received 28 July 2021
• Revised 25 August 2021
• Accepted 30 August 2021

DOI:https://doi.org/10.1103/PhysRevB.104.115304