Reprogrammable MEMS-based fabry–perot pixel photomask

Abstract

Our pioneering reprogrammable photomask based on microelectromechanical systems offers a pathway toward adaptive lithography that remains compatible with conventional stepper systems. In this work, we demonstrate for the first time optical patterning using a MEMS-based Fabry–Perot pixel photomask in a standard photolithography stepper. The approach relies on Fabry–Perot interference in an air-gap cavity, where electrostatic tuning of miniature suspended membranes switch each pixel between ON and OFF states at the 365 nm i-line wavelength. The device is implemented as a reticle-format module integrating a 10 × 10 MEMS Fabry–Perot pixel array with on-board PCB control, wireless programming, and photodiode-based synchronization to the stepper exposure shots. Photolithography was performed on a positive-tone photoresist using matrix-addressed pixels, where predefined programmed states were updated between exposures. A systematic dose test was used to map the resist response under pixelated exposure, followed by dose-resolved analysis that defines the process margin where Fabry–Perot modulation produces a clear distinction between resist development states. Using a pixel aperture of approximately 2.7 μm, printed resist features with lateral dimensions down to ~ 1.7 μm were obtained. These results show that our programmable photomask can deliver lithographically meaningful dose modulation after projection through stepper optics. This work establishes a practical foundation for reprogrammable photomask technology compatible with industrial semiconductor equipment, potentially accelerating the development cycle of new microelectronic circuits and opening a new paradigm in semiconductor design, where each die can be individualised.