Metrology of optically-unresolved features using interferometric surface profiling and RCWA modeling.
Peter de Groot1, Xavier Colonna de Lega, Jan Liesener
1Zygo Corporation, Laurel Brook Road, Middlefield, CT 06457, USA. peterd@zygo.com
Optics Express
|June 11, 2008
Summary
Rigorous coupled wave analysis (RCWA) interprets 3D microscopy profiles to measure nanoscale surface features. This technique accurately determines silicon etch depth and lateral widths, demonstrating high precision for microelectronics applications.
Area of Science:
- Nanotechnology
- Optical Metrology
- Surface Science
Background:
- Characterizing sub-wavelength surface features is crucial for microelectronics and nanotechnology.
- Traditional microscopy methods often lack the resolution to accurately measure optically-unresolved dimensions.
Purpose of the Study:
- To demonstrate the capability of Rigorous Coupled Wave Analysis (RCWA) in interpreting 3D white-light interference microscopy profiles.
- To reveal the dimensions of optically-unresolved surface features with high accuracy and repeatability.
Main Methods:
- Utilized Rigorous Coupled Wave Analysis (RCWA) to process 3D white-light interference microscopy data.
- Measured silicon etch depth and lateral widths of grating structures with varying pitches.
Main Results:
- RCWA-interpreted measurements of silicon etch depth for a 450-nm pitch grating showed excellent correlation (R²=0.995) with Atomic Force Microscopy.
- Achieved a repeatability of 0.11 nm for etch depth measurements.
- Demonstrated sub-nanometer sensitivity (<1 nm) to 80-nm lateral widths on 190-nm pitch gratings.
Conclusions:
- RCWA is a powerful tool for quantitative analysis of 3D microscopy data, enabling precise measurement of nanoscale surface features.
- The technique offers high accuracy and repeatability, suitable for critical dimension metrology in semiconductor manufacturing and nanotechnology.
