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Ultra-high efficiency multilayer blazed gratings through deposition kinetic control
D L Voronov1, E H Anderson, E M Gullikson
1Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA. dlvoronov@lbl.gov
Optics Letters
|May 26, 2012
Summary
Researchers optimized multilayer-coated blazed gratings (MBG) by adjusting sputtering gas pressure. This resulted in a new record diffraction efficiency of 44% for Mo/Si multilayers at 13.1 nm.
Area of Science:
- Optics and Photonics
- Materials Science
- Thin Film Deposition
Background:
- Diffraction efficiency in multilayer-coated blazed gratings (MBG) is critically dependent on the precise structure of sawtooth-shaped layers.
- Optimizing multilayer growth on sawtooth substrates is essential to minimize groove distortion and interface roughening.
Purpose of the Study:
- To optimize the growth of sputter-deposited Molybdenum/Silicon (Mo/Si) multilayers on sawtooth substrates.
- To investigate the effect of sputtering gas pressure on multilayer perfection and grating performance.
Main Methods:
- Sputter deposition of Mo/Si multilayers onto sawtooth substrates.
- Systematic variation of sputtering gas pressure during the deposition process.
- Characterization of the resulting multilayer structure and diffraction efficiency.
Main Results:
- A new method for optimizing Mo/Si multilayer growth on sawtooth substrates was developed by controlling sputtering gas pressure.
- Achieved a record diffraction efficiency of 44% for an optimized MBG.
- The optimized MBG had a groove density of 5250 lines/mm and was tested at a wavelength of 13.1 nm.
Conclusions:
- Sputtering gas pressure is a critical parameter for achieving high-quality Mo/Si multilayers on sawtooth substrates.
- The optimized growth process enables significant improvements in the diffraction efficiency of MBGs.
- This work sets a new benchmark for the performance of Mo/Si MBGs in the extreme ultraviolet spectrum.
