Grinding residual stresses of silicon wafers affect the performance of IC circuits. Based on the wafer rotation ultra-precision grinding ma-chine, the residual stress distribution along grinding marks and ground surface layer depth of the ground wafers are investigated using Raman microspectroscopy. The results show that the ground wafer surfaces mainly present compressive stress. The vicinity of pile-ups between two grinding marks presents higher a compressive stress. The stress value of the rough ground wafer is the least because the material is removed by the brittle fracture mode. The stress of the semi-fine ground wafer is the largest because the wafer surface presents stronger phase trans-formations and elastic-plastic deformation. The stress of the fine ground wafer is between the above two. The strained layer depths for the rough, semi-fine, and fine ground wafers are about 7.6 m, 2.6 m, and 1.1 m, respectively. The main reasons for generation of residual stresses are phase transformations and elastic-plastic deformation.
A model for calculating friction torque during the chemical mechanical polishing(CMP) process is presented,and the friction force and torque detection experiments during the CMP process are carried out to verify the model.The results show that the model can well describe the feature of friction torque during CMP processing. The research results provide a theoretical foundation for the CMP endpoint detection method based on the change of the torque of the polishing head rotational spindle.
