Mask-less ultraviolet photolithography based on CMOS-driven micro-pixel light emitting diodes

We report on an approach to ultraviolet (UV) photolithography and direct writing where both the exposure pattern and dose are determined by a complementary metal oxide semiconductor (CMOS) controlled micro-pixellated light emitting diode array. The 370nm UV light from a demonstrator 8 x 8 gallium nitride micro-pixel LED is projected onto photoresist covered substrates using two back-to-back microscope objectives, allowing controlled demagnification. In the present setup, the system is capable of delivering up to 8.8W/cm(2) per imaged pixel in circular spots of diameter similar to 8 mu m. We show example structures written in positive as well as in negative photoresist