Vertically Integrated Self‐Monitoring AlGaN‐Based Deep Ultraviolet Micro‐LED Array with Photodetector Via a Transparent Sapphire Substrate Toward Stable and Compact Maskless Photolithography Application

Abstract

Drawing inspiration from modern integrated circuit systems composed of various electronic components built on a single silicon platform, the emerging integrated photonics can also follow a similar trend in the pursuit of expanded optical functionalities in constructing compact optoelectronic systems. Herein, vertically integrated a micro‐scale light‐emitting diode (micro‐LED) array with a photodetector (PD) side‐by‐side through a transparent sapphire substrate is proposed. The downward emitted photons from the micro‐LEDs can easily transmit through the transparent sapphire and then be captured by the PD fabricated on the backside of the sapphire. Additionally, by integrating a feedback electrical circuit, a self‐stabilized light output power is demonstrated from the micro‐LED array in such vertically integrated LED/PD architecture, which cannot only monitor the fluctuation of light intensity from the micro‐LED array over time but also provide a constant output feedback to ensure a stable light output power. Such a compact and stable DUV light source composed of micro‐LED array is then employed for constructing a DUV maskless photolithography system. To best of our knowledge, this is the first demonstration of maskless photolithography based on DUV micro‐LED active matrix. The proposed vertically‐stacked optical device architecture by leveraging the transparent substrate offers a new path toward the realization of future integrated photonic systems.