Automated alignment in mask-free photolithography enabled by micro-LED arrays

Stonehouse, M. and Blanchard, A. and Guilhabert, B. and Zhang, Y. and Gu, E. and Watson, I. M. and Herrnsdorf, J. and Dawson, M. D. (2021) Automated alignment in mask-free photolithography enabled by micro-LED arrays. Electronics Letters, 57 (19). pp. 721-723. ISSN 0013-5194 (

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We present an automated control system for positioning on the micro scale, based on the principles of single pixel imaging and fluorescence. By using the projected output of a chequerboard array of CMOS controllable μ-LEDs at a suitable wavelength, we are able to spatially locate, track and automatically align to fluorescent markers. Using this system, positioning is demonstrated with accuracy on the order of 20 μm. We present a maskless photo-lithography system using the automated control capability and a second μ-LED array to photo-cure customisable structures in photoresist with alignment referenced to the fluorescent markers.