Metal-Embedded SU-8 Slab Techniques for Low-Resistance Micromachined Inductors

Abstract

This work presents new fabrication technique for micro power-inductors by using metal-embedded SU-8 slab techniques. This techniques used X-ray lithography to fabricate high aspect-ratio LIGA-like micro-structures in form of embedded structure in SU-8 slab and applied for inductor’s winding fabrication with aspect-ratio of 10. Thishigh-aspect ratiostructure can provide very low resistance winding but preserve small form factor and low profile. Inductors were designed as pot-core structures with8 μm-thick permalloy core and 250 μm-thick copper winding. 4-types of inductors were fabricated including 3, 5, 10 and 16 turns in the area of 1.8 mm² to 9.5 mm². All inductors have overall heights of 370 μm, measured inductance value in a range of 70 nH to 1.3 μH at 1 MHz and DC resistance value of 30 mΩ to 336 mΩ for 3 turns to 16 turns respectively. From this result, high aspect-ratio inductors show good results including low-resistance, high inductance, and a small form factor as expected.