Sub-wavelength printing in the deep ultra-violet region using Displacement Talbot Lithography

• A Displacement Talbot lithographic system at 266 nm exposure wavelength is realized.
• 75 nm printing resolution and large depth of focus are achieved.
• Uniform printing of large-area 150 nm-period line/space gratings is demonstrated.
• The application of the technique to wire-grid polarizers is proposed.

Printing of sub-100 nm half-pitch periodic structures is demonstrated using Displacement Talbot Lithography (DTL) and a deep ultra-violet light source. DTL is a recently developed mask-based photolithography for forming high-resolution periodic structures over large areas using a relatively simple and low-cost system. A phase shift mask consisting of a 40 × 40 mm2 transmission grating with a half-pitch of 150 nm is fabricated by electron-beam lithography followed by reactive ion etching. The geometry of the phase grating is optimized by numerical simulation. Using this mask, dense line/space patterns and two-dimensional arrays of pillars, both with a half-pitch of 75 nm, are printed onto silicon wafers. This new technique is suitable for uniform and high-throughput patterning of large-areas for such applications as moths-eye anti-reflective nanostructures, distributed feedback lasers, zeroth-order gratings, wire-grid polarizers and engineered substrates for LEDs.

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