Research on femtosecond infrared laser cutting 4H-SiC wafer

Abstract

As a third-generation semiconductor, SiC has the advantages of high band gap, high breakdown field strength, high saturated electron drift speed, and high thermal conductivity. It is used as a substrate material to make power electronic devices. It is widely used in 5G, new energy vehicles, consumer electronics, aerospace and other fields. However, due to the characteristics of hard and brittle and the small thickness of SiC wafer, high-quality cutting is difficult. In this paper, a femtosecond laser with pulse width of 500 fs, center wavelength of 1030 nm, repetition rate of 1 Hz - 40 MHz, and maximum single pulse energy of 200 μJ was used to cut 4H-SiC wafers with a thickness of 360 μm. The ablation experiment was carried out under different pulse energy and ablation time, and the ablation threshold of 4H-SiC at a wavelength of 1030 nm was 268.6 mJ/cm2. The single factor control method was used to research the influence of average power, scanning speed, scanning times, defocusing amounts on cutting depth and taper. The elements of cutting section was analyzed with energy dispersive spectrometer.