Study on nucleation and propagation of median cracks generated by scratching single crystal silicon

Abstract

As a widely used semiconductor material, single crystal silicon inevitably suffers from sub-surface damage in mechanical processing, and the study of stress field generated by scratching single crystal silicon is of great significance for the prediction and control of subsurface damage. However, few studies have extended the calculation model of scratching-induced stress field to single crystal silicon and linked the scratching-induced stress field to the nucleation and propagation of median cracks. So in this paper, the calculation model of the stress field generated by scratching Si (100) plane along different crystal directions is established by the superposition of the elastic stress field and the residual stress field. According to the calculation model, the stress field distribution beneath conical scratch indenter is obtained, and then the nucleation and propagation laws of median cracks generated by scratches in different directions are analyzed. It is found that the nucleation position of median cracks generated by scratching is on the elasto-plastic interface at the front end of conical scratch indenter, and the function relationship between the propagation direction of median cracks and the half-angle of conical scratch indenter is obtained. The prediction results of median crack propagation direction are in good agreement with experimental results. Further, by analyzing the maximum value of the tensile stress generated by scratching and the fracture toughness of the median crack crystal plane, it is found that the length of the median crack generated by the scratch in [01¯1] direction is longer than that generated by the scratch in [001¯] direction under the same condition, and the large half-angle of conical scratch indenter will inhibit the propagation of median cracks.