High inductance 3D arch inductor based on non-photosensitive polyimide

Due to their low parasitic capacitance, minimal substrate losses, and high inductance values, three-dimensional MEMS inductors are increasingly used in microelectronics applications, such as MEMS sensors, RF MEMS, and energy storage devices. Conventional fabrication techniques, including UV-LIGA lithography and through‑silicon vias (TSV), are commonly employed to create high-aspect-ratio structures for 3D inductors. However, these processes are often complex and challenging. To simplify the process, we proposed a novel fabrication method for arched inductors utilizing non-photosensitive polyimide. The high viscosity of polyimide facilitates the formation of sloped sidewalls during development, eliminating the need for high-aspect-ratio structures in the inductor fabrication. By controlling the development time, we achieve the desired polyimide sidewall morphology. Additionally, to achieve high inductance, a high-permeability Co-based amorphous alloy wire was used as the magnetic core of the inductor. The maximum inductance of the inductor can reach 1710 nH at an excitation frequency of 71.4 MHz.