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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