Integrated microinductors on semiconductor substrates for power supply on chip (Invited)

Microinductors were fabricated using electrodeposition for integration on semiconductor substrates. The process was optimised through validated models developed to focus on efficiency and footprint. Lithographic processing was performed to microfabricate Cu coils over a magnetic core. A racetrack design was used to maximise the high frequency response, yielding high inductance density and low DC resistance. The magnetic core was subsequently closed using a magnetic thin film deposition over a dielectric deposited on the Cu coils. Homogeneous ferromagnetic alloy, Ni45Fe55 of uniform thickness over a high aspect-ratio 3D structure has been achieved. Ni45Fe55 was chosen for the fabrication of micromagnetic cores due to its relatively high saturation flux density (1.6 T), resistivity (48 mΩ cm) and anisotropy field (9.5 Oe). The rationale, design, microfabrication process and characterisation results are presented