Surface Roughness Model of Ground 4H-SiC Considering Ductile and Brittle Removal

Surface roughness is a critical indicator to evaluate the quality of ground surfaces for 4H-SiC. Determining surface roughness experimentally is a time-consuming and laborious process, and developing a reliable model for predicting surface roughness is a key challenge in 4H-SiC grinding. However, the existing models for surface roughness in wafer rotational grinding fail to yield reasonable results because they do not adequately consider the processing parameters and material characteristics. In this study, a new analytical model for surface roughness in 4H-SiC wafer rotational grinding is proposed, which comprehensively incorporates the grinding conditions and material characteristics of brittle substrate. This model derives and calculates the material's elastic recovery coefficient based on contact mechanics and elastic contact theory. Subsequently, we modified the grain depth-of-cut model by incorporating elastic recovery coefficient. Additionally, we considered the co-existing of machining-induced ductility and brittleness of the substrate surface under random grain depth-of-cut distribution that conforms to the Rayleigh distribution. To validate the accuracy of the proposed model, a series of grinding experiments are conducted using various grain depth-of-cut to produce 4H-SiC wafers with different surface roughness values. These results are then compared with those predicted by both the proposed model and the existing models. The findings demonstrate that the predictions obtained from the proposed model exhibit better agreement with the experimental results. This research addresses the need for an improved surface roughness model in 4H-SiC wafer rotational grinding.