Global alignment reference strategy for laser interference lithography pattern arrays

Area of Science:

• Nanotechnology and Materials Science
• Optical Engineering
• Metrology

Background:

• Large-area gratings are essential components in diverse engineering fields.
• Traditional interference lithography methods face challenges in large-area fabrication due to optical aperture size limitations.

Purpose of the Study:

• To propose and demonstrate a novel method for fabricating large-area laser interference lithography (LIL) pattern arrays.
• To enable precise global alignment of phase, period, and tilt angle across the entire patterned area.

Main Methods:

• Implementation of a global alignment reference strategy utilizing two reference gratings (one detached, one fixed).
• Adjustment of exposure area by alternating beam and substrate movement for precise control.
• Fabrication of a 3x3 grating array on a large substrate.

Main Results:

• Successful fabrication of a large-area grating array with high-accuracy alignment.
• Experimental validation using a Fizeau interferometer showing continuous -1st-order diffraction wavefront.
• Demonstration of effective and efficient alignment across all regions of the interference lithography pattern array.

Conclusions:

• The proposed global alignment strategy effectively overcomes limitations in large-area grating fabrication.
• This technique offers high accuracy and efficiency for fabricating periodic structures on large substrates.
• The method is adaptable for creating various periodic structures through substrate rotation.