Broadband extreme ultraviolet zeroth order scatterometry for nanostructure metrology

Area of Science:

• Optics and Photonics
• Materials Science
• Nanotechnology

Background:

• Nanofabrication requires high-resolution metrology for critical dimension control.
• Traditional methods often lack the necessary resolution for sub-wavelength features.
• Short-wavelength light sources are essential for advanced nanometrology.

Purpose of the Study:

• To introduce a novel table-top extreme-ultraviolet (EUV) scatterometry technique.
• To enable accurate, non-destructive metrology for nanoscale structures.
• To address the metrology demands of continuous shrinkage in critical dimensions.

Main Methods:

• Utilizing broadband high-harmonic generation (HHG) EUV light source.
• Exploiting the spectrally resolved 0th diffraction order for analysis.
• Employing relative reflectivity measurements and rigorous coupled-wave analysis (RCWA) simulations.
• Implementing a library-based reconstruction approach for data analysis.

Main Results:

• Achieved single-nanometer accuracy for groove height measurements.
• Demonstrated 10 nm accuracy for critical dimension measurements.
• Validated the technique for non-destructive metrology of at-wavelength features.
• Showcased high diffraction efficiency and broadband spectral information retrieval.

Conclusions:

• Broadband EUV HHG 0th order scatterometry offers a fast and reliable metrology solution.
• The method provides high sensitivity and accuracy for sub-diffraction limit features.
• This technique is suitable for process control in advanced nanofabrication.