Si/B(4)C narrow-bandpass mirrors for the extreme ultraviolet

Area of Science:

• Materials Science
• Optics
• Thin Film Technology

Background:

• Multilayer mirrors are crucial for manipulating extreme-ultraviolet (EUV) light.
• Silicon/Molybdenum (Si/Mo) mirrors are a common choice but have limitations in bandpass and rejection.
• Developing alternative materials with improved performance is essential for advanced optical systems.

Purpose of the Study:

• To investigate the performance of Silicon/Boron Carbide (Si/B4C) multilayer mirrors.
• To characterize their structural properties and reflectance in the extreme-ultraviolet spectrum.
• To compare their properties with traditional Si/Mo multilayer mirrors.

Main Methods:

• Sequential sputter deposition of Silicon (Si) and Boron Carbide (B4C) layers.
• Extreme-ultraviolet (EUV) reflectance measurements at various wavelengths and incidence angles.
• Structural characterization of the fabricated multilayer mirrors.
• Annealing studies to assess thermal stability.

Main Results:

• Si/B4C mirrors exhibit narrower bandpass (Δλ) and better off-peak rejection than Si/Mo mirrors.
• Peak reflectance (R(0)) was measured at 0.275 (13.1 nm, normal incidence), 0.34 (18.2 nm, 45°), and 0.30 (23.6 nm, 45°).
• The multilayers demonstrated excellent stability after annealing up to 600°C.

Conclusions:

• Si/B4C multilayer mirrors present a promising alternative to Si/Mo for EUV applications.
• Their narrow bandpass and high off-peak rejection are advantageous for specific spectral filtering.
• The observed thermal stability ensures their reliability in demanding environments.