Laser slicing of 4H-SiC wafers based on picosecond laser-induced micro-explosion via multiphoton processes

Abstract

Silicon carbide has many advantages and a wide range of applications. The fabrication of a thin silicon carbide wafer using diamond wire cutting has become problematic because it resulted in chipping, delamination, and heating. In this work, it is proved that the 1064 nm picosecond laser creates a multiphoton-induced micro-explosion in 4H-SiC, which confined the microburst layer near the focus of the laser beam and made a cutting width of less than 2 μm. As a result, the 4H-SiC was decomposed into amorphous Si and C owing to the transient high temperature generated. Optimized processing parameters were investigated, such as the etching speed v and etching interval d at the optimized pulse energy of 30 μJ and a laser repetition frequency of 100 kHz. Eventually, two 4H-SiC wafers were successfully manufactured, which have an area of 1 cm × 1 cm and a thickness of 250 μm without residual stress on the sliced surface. The wafer minimum surface roughness was approximately 1.8 μm with a standard deviation of ≤ 0.12 μm. The structure and composition of 4H-SiC were investigated after laser slicing. This technology has critical applications for slicing hard and brittle material and thinning many semiconductors devices' backsides.