Bio-inspired 3D funnel structures made by grayscale electron-beam patterning and selective topography equilibration

Kirchner, Robert; Guzenko, Vitaliy A.; Rohn, M.; Sonntag, E.; Mühlberger, M.; Bergmair, Iris; Schift, Helmut

doi:10.1016/j.mee.2015.02.014

Cited by 29 publications

(18 citation statements)

References 13 publications

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“…This process is termed the “TASTE” process. It opens up lithography‐based reflow to a lot of new 3D contours that were not possible without material contrast . For reducing the surface roughness without modifying the contour of a homogeneous material, one needs a surface sensitive exposure followed by reflow.…”

Section: Resultsmentioning

confidence: 99%

Selective Surface Smoothening of Polymer Microlenses by Depth Confined Softening

Chidambaram

Kirchner

Fallica

et al. 2017

Adv Materials Technologies

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Section: Resultsmentioning

confidence: 99%

Selective Surface Smoothening of Polymer Microlenses by Depth Confined Softening

Chidambaram

Kirchner

Fallica

et al. 2017

Adv Materials Technologies

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“…This is mainly due to the fact that the entire film is exposed along the beam path when using single photon absorption processes. Similarly, the higher resolution grayscale methods based on electron and ion beams are mostly suitable for diffractive optics with film resist thickness below 10 µm for electrons and even thinner for ions [14,15]. A true 3D capable method such as 2PP-DLW allows for full freeform designs without restrictions on the size of the micro-optics [16].…”

Section: Layering Versus Postprocessing For Roughness Smootheningmentioning

confidence: 99%

Surface smoothening of the inherent roughness of micro-lenses fabricated with 2-photon lithography

Schift

Kirchner

Chidambaram

et al. 2018

Nanophotonics Australasia 2017

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Two-photon polymerization by direct laser writing enables to write refractive micro-optical elements with sub-µm precision. The trajectories and layering during the direct writing process often result in roughness in the range of the writing increment, which has adverse effects for optical applications. Instead of increasing overlap between adjacent voxels, roughness in the range of 100 nm can be smoothed out by post-processing. For this a method known as TASTE was developed, which allows polishing of surfaces without changing the structural details or the overall shape. It works particularly well with thermoplastic polymers and enables sub-10 nm roughness. The optical quality was confirmed for an array with several 100 microlenses.

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“…The fabrication schemes include 3-D methods such as grayscale lithography, which tunes the resist profile by the exposure dose, and especially, two-photon polymerization (2PP) lithography, which builds 3-D structures out of thin discrete layers. Grayscale approaches are either based on masks with varying transmission grades (grayscale masks), direct writing methods, [1][2][3][4][5] or multiple exposures. [6][7][8][9] While the first one is well established for i-line optical lithography (365 nm wavelength), higher resolution, direct writing methods are based on sequential scanning of photons, electrons, or ion beams on predefined trajectories through the material.…”

Section: Introductionmentioning

confidence: 99%

Benchmarking surface selective vacuum ultraviolet and thermal postprocessing of thermoplastics for ultrasmooth 3-D-printed micro-optics

2018

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State-of-the-art, polymeric, refractive micro-optics simultaneously require an ultrasmooth threedimensional (3-D) surface and a precise geometry for excellent optical performance with minimal stray light. In earlier work, we have established a surface finishing process for thermoplastic polymer master structures that is only effective on the surface and does not affect the designed optical geometry, thus enabling polishing without touching. Therewith, the high curvature corners of a 50-μm-tall optical diffuser device were maintained while the surface roughness was reduced to about 10-nm root mean square. For this, 3-D master structures were first fabricated by direct write laser-lithography with two-photon polymerization. The master structures were replicated into poly(methyl methacrylate) through a poly(dimethyl siloxane) intermediate replication stamp. Finally, all structures were surface-polished by selective high-energy photon exposure and thermal postprocessing. In this work, we focus on the comparison of the surface smoothening using either postprocessing or dedicated direct writing strategies. For this comparison, strategies for modifying the exposed voxel size and the writing discretization being the primary source of roughness were tested by sweeping the laser exposure dose for two different resist materials and objectives. In conclusion, the postprocessing smoothening resulted in a lower roughness compared to a direct writing strategy-even when 50-nm vertical discretization steps were usedand still enabled 10 times shorter writing times.

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Bio-inspired 3D funnel structures made by grayscale electron-beam patterning and selective topography equilibration

Cited by 29 publications

References 13 publications

Selective Surface Smoothening of Polymer Microlenses by Depth Confined Softening

Selective Surface Smoothening of Polymer Microlenses by Depth Confined Softening

Surface smoothening of the inherent roughness of micro-lenses fabricated with 2-photon lithography

Benchmarking surface selective vacuum ultraviolet and thermal postprocessing of thermoplastics for ultrasmooth 3-D-printed micro-optics

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