Design and manufacturing of high inductance planar coils for small scale sensing applications

This work addresses the design and fabrication of small scale planar coils with high number of turns (> 100) and self inductances up to 32 H suitable for the enhancement of inductive sensors performances. First, the modified Wheeler’s formula is used to determine the optimal number of turns in order to achieve the highest inductance. Then, a simple process flow based on inductively coupled plasma (ICP) etching of sputtered aluminum on silicon substrate is presented and the key aspects of the processing are discussed. Finally, the fabricated coils are characterized both electrically and morphologically and the measurements are compared to the model showing good agreement with the theoretical predictions.