Line-edge roughness transfer function and its application to determining mask effects in EUV resist characterization

Area of Science:

• Semiconductor Manufacturing
• Lithography Technology
• Materials Science

Background:

• Line-edge roughness (LER) in photoresist is a major challenge for advanced lithography, including extreme-ultraviolet (EUV) lithography.
• Accurate resist characterization and differentiation of LER sources are essential for next-generation lithography.

Purpose of the Study:

• To investigate the coupling of mask line-edge roughness (LER) to resist LER in projection lithography.
• To introduce and define a novel LER transfer function (LTF) for analyzing this coupling.

Main Methods:

• Analytical modeling to understand mask-to-resist LER transfer.
• Computer simulations to quantify LER coupling effects.
• Experimental validation using current EUV masks and projection lithography.

Main Results:

• A new imaging transfer function, the LER transfer function (LTF), is presented, distinct from conventional MTF and OTF.
• The study quantifies the impact of mask LER on resist LER.
• Experimental data confirms the influence of EUV masks on LER in lithography.

Conclusions:

• Understanding and controlling mask LER is critical for achieving low LER in EUV lithography.
• The developed LTF provides a new framework for analyzing LER transfer in lithographic processes.
• This research contributes to mitigating LER challenges in next-generation semiconductor manufacturing.