Wafer defect detection based on polarization modulation

Dark-field inspection systems have high detection sensitivity and high resolution, and are widely used in the field of bare wafer inspection. By adding polarization elements to the dark-field detection system, the optical scattering on bare wafer surface can be used to detect defects, and the detection accuracy can be improved. The scattered light not only depends on the polarization state of the incident light, but is also affected by the physical properties of the defects on the wafer surface and the complexity of the scattering process. When there are defects on the wafer surface, such as dirt, particles, scratches, the scattered light will change. This change can be detected by a dark-field detection system to identify the defect. However, how to choose the appropriate polarized light so that the detected signal intensity is higher is the main concern in polarization modulation techniques. In this paper, several common defect types in wafer defect detection are simulated. Linear polarized light is used as the illumination source of wafer defect detection system. By changing the polarization state and incidence angle of the illumination source, a simulation model of wafer defect detection based on polarization modulation is established. The simulation results show that by adjusting the polarization state and incidence angle of the illumination source, the intensity detection signal of certain types of defects can be improved, so as to guide the polarization illumination and detection involved in wafer defect detection system.