Mask-free photolithographic exposure using a matrix-addressable micropixellated AllnGaN ultraviolet light-emitting diode

We report the integration of a UV-curable polymer microlens array onto a matrix-addressable, 368-nm-wavelength, light-emitting diode device containing 64×64 micropixel elements. The geometrical and optical parameters of the microlenses were carefully chosen to allow the highly divergent emission from each micropixel to be collimated into a narrow beam of about 8-µm diam, over a distance of more than 500 µm. This device is demonstrated as a photolithographic exposure tool, where the pattern-programmable array plays the role both of light source and photomask. A simple pattern comprised of two disks having 16-µm diam and 30-µm spacing was transferred into an i-line photoresist.