Investigation on fabrication of nanoscale patterns using laser interference lithography

Area of Science:

• Materials Science
• Nanotechnology
• Optics

Background:

• Laser interference lithography (LIL) is a maskless technique for fabricating nanoscale patterns.
• Lloyd's mirror interferometer enables simple, large-area patterning.
• Understanding LIL parameter effects is crucial for optimizing nanoscale structure fabrication.

Purpose of the Study:

• To investigate the effects of key parameters on LIL for nanoscale pattern generation.
• To achieve uniform dot and line patterns with controlled dimensions.
• To optimize exposure time and material usage for LIL.

Main Methods:

• Utilized a Lloyd's mirror interferometer with a 257 nm wavelength laser.
• Investigated parameters including exposure dosage, beam intersection angle, and light source power.
• Employed positive photoresist DHK-BF424 on a silicon substrate.
• Applied bottom anti-reflective coating (DUV-30J) for line structure enhancement.

Main Results:

• Achieved uniform dot patterns (20 mm x 20 mm) with half pitch sizes of 190, 250, and 370 nm.
• Reduced exposure time to 12/12 sec by increasing beam power to 0.600 mW/cm2 for DHK-BF424 photoresist.
• Confirmed improvements in line structures using a bottom anti-reflective coating.

Conclusions:

• LIL is an effective maskless technology for large-area nanoscale patterning.
• Parameter optimization significantly influences pattern quality and fabrication efficiency.
• LIL offers advantages in speed and simplicity for creating nanoscale dot and line structures.