Deep subwavelength interference lithography with tunable pattern period based on bulk plasmon polaritons.

Area of Science:

• Plasmonics and Nanofabrication
• Metamaterials and Optics

Background:

• Surface plasmon polariton interference lithography offers high resolution but suffers from inflexible pattern pitch due to fixed excitation modes.
• This limitation restricts its application in micro- and nanofabrication processes.

Purpose of the Study:

• To propose a large-area deep subwavelength interference lithography technique with a tunable pattern period.
• To overcome the fixed-pitch limitation of previous plasmonic lithography methods.

Main Methods:

• Utilized bulk plasmon polaritons (BPPs) for interference lithography.
• Employed hyperbolic metamaterials to confine and guide BPPs.
• Tuned the incident angle to modify the spatial frequencies of BPPs, thereby altering the interference pattern pitch.

Main Results:

• Demonstrated continuous tunability of the interference pattern pitch.
• Achieved generation of 1D and 2D periodic patterns with resolutions from 45 nm (~λ/10) to 115 nm (~λ/4) using 436 nm illumination.
• Showcased the method's applicability for large-area deep subwavelength fabrication.

Conclusions:

• The proposed BPP-based interference lithography offers a flexible and tunable approach for nanoscale fabrication.
• This technique overcomes the inherent limitations of fixed-pitch lithography, enabling versatile pattern generation.
• A general design method for such systems is discussed, paving the way for advanced nanofabrication.