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

Abstract

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.

Investigation of coherent Fourier scatterometry as a calibration tool for determination of steep side wall angle and height of a nanostructure

“…CFS can be used as a direct measurement-based technique eliminating the need for modelling in detecting subwavelength isolated particles or subtle alterations in the parameters of nanostructures [30,31], and a traditional model-based technique for the characterization of periodic nanostructures [32][33][34]. Notably, recent advancements have seen CFS successfully modeling and experimentally detecting an isolated defect in the periodic nanostructure [35]. However, compared to other techniques CFS is very sensitive to the alignment and stability of the system, and is limited by the surface roughness of the substrate and the noise of the camera pixels [36].…”