Photolithography-Based Nanopatterning Using Re-entrant Photoresist Profile

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Photolithography is a standard technique for micron-scale patterning in research labs.
• Achieving nanoscale resolution typically requires short-wavelength light and complex optics, increasing cost and complexity.

Purpose of the Study:

• To develop a novel subwavelength patterning method using conventional photolithography equipment.
• To achieve nanoscale feature sizes without advanced optical tools.

Main Methods:

• Utilizes the re-entrant geometry of image reversal photoresist.
• A secondary mask is created by isotropic metal deposition over the photoresist profile.
• Ultrasonic vibrations in acetone are used to crack the metal layer, reducing feature size.

Main Results:

• Achieves controlled reduction of initial mask pattern width by up to 400 nm.
• Demonstrates sub-100 nm scale linear patterns.
• Patterns are compatible with subsequent deposition and dry-etching processes.

Conclusions:

• The novel method enables cost-effective nanoscale patterning with conventional i-line mercury lamps.
• Applicable to various pattern shapes for electronic device fabrication, including AlGaN/GaN high-electron-mobility transistors.