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Compact Lens-less Digital Holographic Microscope for MEMS Inspection and Characterization
Published on: July 5, 2016
Extreme-ultraviolet lensless Fourier-transform holography
S H Lee1, P Naulleau, K A Goldberg
1Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, Berkeley, California 94720, USA. shlee@lbl.gov
Applied Optics
|March 22, 2008
Summary
We developed a holographic aerial image monitoring technique for extreme-UV (EUV) lithography, achieving 100-nm resolution. This method enables precise imaging performance assessment of EUV optical systems.
Area of Science:
- Optics and Photonics
- Lithography Technology
- Metrology
Background:
- Extreme-UV (EUV) lithography is crucial for advanced semiconductor manufacturing.
- Monitoring the coherent imaging performance of EUV optical systems is essential for yield.
- Existing methods may lack the resolution or applicability for certain EUV lithography challenges.
Purpose of the Study:
- To introduce and validate a novel holographic aerial image-recording technique.
- To demonstrate 100-nm resolution monitoring of EUV lithographic optical systems.
- To explore the application of this technique for mask-blank defect characterization.
Main Methods:
- Lensless Fourier-transform holography using synchrotron-based illumination.
- Implementation within an EUV phase-shifting point-diffraction interferometer.
- Characterization of a 10x Schwarzschild objective and various object patterns.
Main Results:
- Achieved 100-nm resolution holographic aerial image monitoring.
- Demonstrated the technique's capability to assess coherent imaging performance.
- Obtained good agreement between experimental results and simulations for a prototype EUV optic.
Conclusions:
- The holographic aerial image-recording technique is a viable method for high-resolution monitoring in EUV lithography.
- This technique can be applied to characterize EUV optical systems and mask-blank defects.
- Further development could enhance defect detection and process control in EUV lithography.
