Ultrafast Laser Micro/Nano Processing of GaN for Next‐Generation Microelectromechanical Systems (MEMS) Applications

Gallium nitride (GaN) has established itself as a wide‐bandgap semiconductor, driving advances in radio‐frequency devices, solid‐state lighting, and high‐power electronics. Its chemical stability, strong piezoelectric properties, and biocompatibility have turned GaN into a crucial candidate for next‐generation microelectromechanical systems (MEMS), including sensors, resonators, and energy harvesters operating in harsh environments. However, GaN's transition from planar devices to 3D MEMS structures is limited by its hardness, brittleness, and chemical inertness. Conventional fabrication methods induce heat‐affected zones, lattice damage, and micro‐cracks, significantly reducing device yield and performance. This review presents a comprehensive analysis of ultrafast laser micro/nano processing as a transformative, non‐contact manufacturing paradigm to overcome these limitations. We first elucidate the fundamental mechanisms of laser–material interactions, distinguishing between picosecond (ps) and femtosecond (fs) regimes, with attention to non‐linear absorption, ionization dynamics, and non‐thermal ablation enabling submicron resolution with minimal collateral damage. We investigate laser methodologies including maskless direct writing, laser lift‐off (LLO), and laser‐induced periodic surface structures (LIPSS), highlighting their integration into high‐performance GaN MEMS devices for enhanced sensitivity. We explore hybrid integration with complementary metal‐oxide‐semiconductor (CMOS) technology and artificial intelligence (AI)‐driven optimization to address throughput challenges, offering pathways toward wafer‐scale manufacturing of next‐generation GaN MEMS.