Broadband coherent Fourier scatterometry: A two-pulse approach.

Area of Science:

• Optics and Photonics
• Metrology
• Materials Science

Background:

• Coherent Fourier scatterometry (CFS) is a powerful technique for sample characterization.
• Traditional CFS implementations often face limitations in spectral range and cost-effectiveness.

Purpose of the Study:

• To demonstrate a broadband implementation of CFS using a supercontinuum source.
• To enable spectrally resolved diffraction pattern acquisition for enhanced analysis.
• To present a cost-effective approach for multi-wavelength CFS data collection.

Main Methods:

• Utilized a supercontinuum light source for broadband illumination.
• Employed a two-pulse approach with variable time delay, similar to Fourier-transform spectroscopy.
• Captured interferograms in the Fourier plane for each camera pixel.
• Performed per-pixel Fourier transforms as a function of delay to retrieve spectrally resolved diffraction patterns.

Main Results:

• Successfully demonstrated the physical principle of the two-pulse CFS approach.
• Presented experimental realization and results for a silicon line grating.
• Acquired multi-wavelength CFS data over a wide spectral range cost-effectively.

Conclusions:

• The broadband CFS implementation offers a cost-effective method for acquiring extensive spectral diffraction data.
• This technique has the potential to enhance reconstruction robustness and sensitivity in applications like dimensional metrology.
• The presented approach paves the way for more advanced optical metrology applications.