Product Code: ICA13_N202
Sub-Wavelength Patterning of Self-Assembled Organic Monolayers Via Non-Collinear Optical Parametric Amplifier
Andreas Aumann, Ruhr-Universitaet Bochum; Bochum Germany
Stella Maragkaki, Ruhr-UniversitäT Bochum; Bochum Germany
Benjamin Schops, Ruhr-UniversitäT Bochum; Bochum Germany
Andreas Ostendorf, Ruhr-UniversitäT Bochum; Bochum Germany
Florian Schulz, UniversitäT Duisburg-Essen; Essen Germany
Anja Schroter, UniversitäT Duisburg-Essen; Essen Germany
Steffen Franzka, UniversitäT Duisburg-Essen; Essen Germany
Nils Hartmann, UniversitäT Duisburg-Essen; Essen Germany
Presented at ICALEO 2013
Self-assembled monolayers (SAMs) are ultra-thin organic monolayers, which can be used in different ways to assemble functionalized surface structures. This potential is caused by the ability of the SAMs to tie further molecules and components through the terminal groups of the organic layers. Well known applications are DNA chips and protein chips. Additional applications for microfluidics and micromechanics require micro and nano structuring of the SAMs. In combination with multi-photon lithography (MPL) SAMs are offering advantageous properties as ultra thin resists with film thicknesses of 1 – 2 nm. Thus, the processing with single pulses is feasible and results in very short processing times without the appearance of bubbles and formation of particles compared to photo resists. In this case, the forward scattering of electrons is reduced to the greatest possible extend by the laser ablation as well. For our experiments, we used a non-collinear optical parametric amplifier (NOPA) which has the ability to generate short pulses in the visible and near-infrared (NIR) range of light. The NOPA can be tuned in the range of 480 nm to 950 nm without spectral gaps. The 100 fs laser pulses provided by the NOPA are reduced to sub-30 fs pulse using a prism compressor.
We used thiol based SAMs as ultra thin layers on gold substrates with a thickness of 40 nm. The selected laser power offers the possibility of ablation of the SAMs without damaging the gold layer. The NOPA system provides the possibility to determine elementary relations relating the dependencies on wavelength and pulse duration. Thereby we investigate the characteristics of thiol-based SAMs as monomolecular resists during etching of gold. We also investigate the wavelength dependencies of the substrate to get an optimal process window for the ablation process. Minimum structure sizes at a 1/e^2 laser spot diameter of about 1 μm are close to 1/5 of the spot diameter.
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