激光剥离对4H-SiC衬底应力及面型的影响研究OA

Under the background of the rapid development of third-generation semiconductors and the growing demand for large-size,low-warp 8-inch(1 inch=2.54 cm)4H-SiC substrates,the traditional multi-wire sawing suffers from large material loss and limited capability in precisely controlling residual stress and wafer shape.However,the existing laser slicing studies are mostly focused on small-size or semi-insulating 4H-SiC,and a systematic understanding of the correlation among process parameters,residual stress,and wafer shape for conductive 8-inch 4° off-axis ingots under engineering conditions is still lacking.In this work,the 8-inch conductive N-type 4° off-axis 4H-SiC ingots are used as the research object.Internal modification is introduced by 1 064 nm picosecond laser irradiation combined with ultrasonic slicing,while the scanning speed(50～400 mm/s)is systematically varied.By means of SEM/TEM/SAED,Raman depth profiling,high-resolution XRD combined with the Stoney equation,lattice stress analysis and full-aperture wafer-shape measurements,a multi-scale evaluation chain is established from the microscopic modified layer to the macroscopic warp of the whole wafer.This paper clarifies the nucleation and propagation mechanism of SiC cracks along the[11-20]crystallographic direction induced by picosecond laser irradiation,and reveals influence of laser scanning speed on the slicing efficiency,stress distribution and wafer shape quality of 8-inch SiC substrates from both micro-and macro-perspectives.The paper provides theoretical support and process-optimization pathways for high-quality laser slicing fabrication of 8-inch 4H-SiC wafers,and offers a reference research idea for achieving controllable wafer shape tuning of SiC substrates based on laser-modified layers.