Direct patterning of TiO₂ using step-and-flash imprint lithography

Area of Science:

• Materials Science and Engineering
• Nanotechnology
• Lithography

Background:

• Step-and-flash imprint lithography (S-FIL) excels at fabricating sub-100 nm features using organic resists.
• Direct patterning of inorganic materials like oxides via S-FIL has been hindered by resist formulation and dispensing challenges.

Purpose of the Study:

• To demonstrate the proof-of-concept for S-FIL of titanium dioxide (TiO2) using a novel acrylate-based formulation.
• To overcome limitations in direct oxide patterning for wafer-scale fabrication.

Main Methods:

• Development of an acrylate-based formulation containing an allyl-functionalized titanium complex with high metal precursor content (48 wt %) and low viscosity (∼5 mPa·s).
• Utilizing automatic dispensing systems for formulation application, followed by UV radiation-induced rapid polymerization.
• Patterning of 100 nm gratings over five 1 cm × 1 cm fields and subsequent high-temperature (450 °C) heat treatment.

Main Results:

• Achieved high-yield (∼95%) S-FIL of the TiO2 precursor formulation, demonstrating good adhesion, spreading, and pattern density insensitivity.
• Successful imprinting of 100 nm gratings.
• Post-treatment conversion to TiO2 anatase nanostructures as small as 30 nm wide, retaining structural integrity and aspect ratio.

Conclusions:

• This work presents a viable S-FIL approach for direct wafer-scale patterning of functional oxides.
• The developed method overcomes previous limitations, paving the way for sub-100 nm scale oxide nanostructure fabrication.