High-sensitivity inspection of the ultra-low-density defects in thin films using dark-field spatial correlation spectrum

A high-sensitivity inspection method for ultra-low-density defects in the thin films is presented by performing spatial correlation calculations on the x-ray dark-field scattering. The sensitivity of defect inspection is theoretically analyzed under varying exposure times and defect thicknesses. The simulation results demonstrate a 25 times increase in inspection sensitivity compared to scanning scattering contrast microscopy (SSCM). An experiment was performed at the Shanghai Synchrotron Radiation Facility and a 56 nm particle defect was successfully inspected with the sensitivity of 8.3. Both theoretical and experimental results indicate that the dark-field spatial correlation spectrum method holds significant potential for advanced defect inspection.