Effect of micromorphology on measurement of residual stress of ground silicon wafers using Raman spectroscopy

Wafer rotation grinding is widely used to obtain thin and ultrathin silicon wafers due to its high precision and efficiency. Residual stress would be introduced in the grinding process, which would cause wafer warpage and even fracture. Raman spectroscopy has long been used to obtain the residual stress states of machined silicon wafers based on the measurement of the frequency shift in the Raman spectra. However, large fluctuations of residual stress values often occur since the measuring point might locate on different micromorphology features, limiting its application. The purpose of this study was to investigate the effect of micromorphological features on the measurement of residual stress using Raman spectroscopy to optimize the residual stress measurement method. The results revealed that the location of the measured points on different micromorphology features has significant impact on the measured residual stress values. The fluctuation shows to be smaller when the measured points are along a line parallel to the scratch marks and larger when the points are along a line perpendicular to the scratch direction. It is recommended that the sampling points should be carefully arranged to obtain more representative values. The study could facilitate the evaluation of residual stress in the grinding process of silicon wafers.