Femtosecond laser materials processing using a digital micromirror device

Eason, R.W., Mills, B., Feinäugle, M., Sones, C.L. and Grant-Jacob, J.A. (2013) Femtosecond laser materials processing using a digital micromirror device. EUROMAT Symposium: A1.I Ultrafast Laser Processing and Functionalization of Materials for Technological Applications, , Seville, Spain. 08 - 13 May 2013.

Abstract

We present the results of our work using a Texas Instruments digital multimirror device (DMD: a pixelated programmable mirror array) for applications in femtosecond materials processing. Unlike other techniques such as electron beam lithography or focussed ion beam processing, DMD-based laser processing allows image field sizes of ~30µm² to be processed using a single femtosecond laser pulse. When combined with step-and-repeat techniques, at laser repetition rates of 1kHz and single pulse energies of ~1mJ, final patterned areas of around 1cm² with sub-micron resolution could be achieved within reasonable (less than 1 hour) time scales.
We have used DMD-based highly demagnified image projection for ablation, multiphoton polymerisation and laser-induced forward transfer (LIFT). Using 800nm femtosecond laser pulses, we have so far produced features by ablation with linewidths of ~400nm in 300 nm thick films, and achieved sub-micron feature sizes in 10 µm thick photoresist via multiphoton processing. For LIFT, we have successfully printed solid-phase materials with few µm feature sizes, and are currently investigating the final aspect ratio (width-to-thickness of printed deposits) that is achievable without causing undesirable shattering or damage. We are also evaluating the role of single pulse versus multipulse exposure for ablation and polymerisation.
For all three techniques, we are evaluating the ultimate resolution and feature sizes achievable, and also (for LIFT) the possibility of stacking deposits to form complex 3-dimensional structures of few µm dimensions. We see DMD-based laser microfabrication as a future technology platform for high-value manufacturing, and during the talk will outline our future plans and current thinking on routine incorporation of DMD technology into laser-based microprocessing workstations.

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Contributors

Author: R.W. Eason

Author: B. Mills

Author: J.A. Grant-Jacob

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