Residual Stress Distribution in Silicon Wafers Machined by Rotational Grinding

Subsurface damage (SSD) and grinding damage-induced stress (GDIS) are a focus of attention in the study of grinding mechanisms. Our previous study proposed a load identification method and analyzed the GDIS in a silicon wafer ground (Zhou et al., 2016, “A Load Identification Method for the GDIS Distribution in Silicon Wafers,” Int. J. Mach. Tools Manuf., 107, pp. 1–7.). In this paper, a more concise method for GDIS analysis is proposed. The new method is based on the curvature analysis of the chip deformation, and a deterministic solution of residual stress can be derived out. Relying on the new method, this study investigates the GDIS distribution feature in the silicon wafer ground by a #600 diamond wheel (average grit size 24 μm). The analysis results show that the two principal stresses in the damage layer are closer to each other than that ground by the #3000 diamond wheel (average grit size 4 μm), which indicates that the GDIS distribution feature in a ground silicon wafer is related to the depth of damage layer. Moreover, the GDIS distribution presents a correlation with crystalline orientation. To clarify these results, SSD is observed by transmission electron microscopy (TEM). It is found that the type of defects under the surface is more diversified and irregular than that observed in the silicon surface ground by the #3000 diamond wheel. Additionally, it is found that most cracks initiate and propagate along the slip plane due to the high shear stress and high dislocation density instead of the tensile stress which is recognized as the dominant factor of crack generation in a brittle materials grinding process.