Impact of mask errors on imaging quality in surface plasmon lithography

Area of Science:

• Nanotechnology
• Optical Engineering
• Materials Science

Background:

• Plasmon lithography utilizes evanescent waves to surpass classical diffraction limits in nanoscale patterning.
• Traditional surface plasmon lithography (SPL) faces challenges with mask fabrication deviations impacting imaging performance.

Purpose of the Study:

• To investigate the imaging performance and process robustness of a surface plasmon resonant cavity lithography (SPRCL) system.
• To compare SPRCL with traditional SPL under various mask fabrication deviations.

Main Methods:

• Development of a lithographic structural model integrating optical transfer function (OTF) theory and rigorous coupled-wave analysis (RCWA).
• Utilizing COMSOL simulations to validate SPRCL performance against global and local feature size variations, defects, and patterning limitations.

Main Results:

• SPRCL demonstrates improved imaging contrast and more stable normalized image log-slope (NILS) under global mask critical dimension (CD) variations, with a mask error enhancement factor (MEEF) from 0.67 to 3.10.
• SPRCL shows a significantly lower average MEEF (1.11) for local CD perturbations compared to SPL, with potential optimization to 0.33.
• SPRCL achieves superior overlay accuracy (46.6%) and high-fidelity imaging (contrast > 0.8, NILS > 1.5) in limited-period patterning.

Conclusions:

• The SPRCL architecture exhibits enhanced process tolerance and superior imaging fidelity compared to traditional SPL.
• SPRCL presents a promising advancement for achieving super-resolution lithography with greater reliability and precision.