Prediction for subsurface damage depth of silicon wafers in workpiece rotational grinding

Workpiece rotational grinding is the primary machining process for the bare wafer flattening and pattern wafer back-thinning of large silicon wafers. However， the grinding process inevitably causes surface and subsurface damage on the ground silicon wafers. The subsurface damage depth of ground silicon wafers is critical for evaluating the grinding process. To predict the subsurface damage depth of silicon wafers in workpiece rotational grinding and optimize the grinding parameters， the wafer surface topography， material removal mechanism， and the underlying fracture mechanics were comprehensively analyzed， and a mathematical relationship among the grain cut depth， surface roughness Ra， and subsurface damage depth was derived. Subsequently， a predictive model for the subsurface damage depth of silicon wafers due to workpiece rotational grinding was established， and silicon wafer grinding experiments were conducted to validate the model. The experimental results indicate that the subsurface damage depth of silicon wafers machined via workpiece rotational grinding increases with the ground surface roughness. The predicted subsurface damage depths of ground silicon wafers are consistent with the actual measured values， and the accuracy of predictive model is less than 10%. These results can provide a basis for the subsurface damage control and parameter optimization of grinding of large-sized silicon wafers. © 2022 Guangxue Jingmi Gongcheng/Optics and Precision Engineering. All rights reserved.