Coherent Fourier scatterometry: a holistic tool for inspection of isolated particles or defects on gratings

Detecting defects on diffraction gratings is crucial for ensuring their performance and reliability. Practical detection of these defects poses challenges due to their subtle nature. We perform numerical investigations and demonstrate experimentally the capability of coherent Fourier scatterometry (CFS) to detect particles as small as 100 nm and also other irregularities that are encountered usually on diffraction gratings. Our findings indicate that CFS is a viable tool for inspection of diffraction gratings.