Nearly amorphous Mo-N gratings for ultimate resolution in extreme ultraviolet interference lithography

Area of Science:

• Materials Science
• Nanotechnology
• Lithography

Background:

• High-resolution patterning is crucial for advanced semiconductor manufacturing.
• Extreme ultraviolet (EUV) interference lithography offers a path to sub-10 nm features.
• Traditional materials for EUV masks face challenges with roughness and efficiency.

Purpose of the Study:

• To fabricate and characterize novel nearly amorphous molybdenum nitride (Mo1-xNx) transmission gratings.
• To evaluate their performance as masks in EUV interference lithography.
• To demonstrate improved resolution and reduced roughness compared to pure molybdenum gratings.

Main Methods:

• Sputter deposition of Mo with N2 incorporation to form Mo1-xNx thin films.
• Characterization using X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD).
• Fabrication of gratings via electron-beam lithography and plasma dry etching.
• Application of gratings as masks in EUV interference lithography.

Main Results:

• Nearly amorphous Mo0.8N0.2 films with negligible grain size were successfully synthesized.
• Mo1-xNx gratings showed significantly reduced line edge roughness compared to pure Mo gratings.
• The Mo1-xNx gratings maintained excellent phase grating properties for EUV wavelengths.
• Dense lines down to 8 nm half-pitch were fabricated using EUV interference lithography with these masks.

Conclusions:

• Nearly amorphous Mo1-xNx is a superior material for high-resolution EUV transmission gratings.
• The developed gratings enable highly efficient diffraction and ultra-low roughness mask fabrication.
• This advancement facilitates the production of sub-10 nm features essential for next-generation microelectronics.