Microfabricated planar coils with high turns density: design and manufacturing

This work addresses the design and the fabrication of small scale square planar coils with high density of turns and self inductances up to 170 µH. First, the modified Wheelers formula is used to determine the optimal number of turns in order to achieve the highest inductance. Then, an effective process flow based on polyimide (PI) and copper processing is presented, and the key aspects of the processing are discussed. Finally, the fabricated coils are characterized both electrically and morphologically, and the results are compared to the model showing good agreement with the theoretical calculations.