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.