Improvement in inductance and Q-factor by laser microstructuring of ferromagnetic on-chip thin film inductors

Abstract

In this work, we examine the potential improvement in inductance (L) and quality factor (Q) of on-chip ferromagnetic thin film inductors through the formation of conical microstructures by localized ultraviolet laser irradiation on ferromagnetic thin film. Parameters affecting L and Q, and arising from the surface modification upon laser irradiation include thickness of the film, size, and density of the structures. The thickness of the film is optimized to 0.2 μm, and at least 18% increase in inductance and 25% increase in Q-factor for NiFe thin film in comparison to the conventional spiral inductor is expected. L and Q values of NiFe films with and without microstructuring are compared, and a 7% increase is predicted for the microstrucired film. The proposed fabrication process, including the laser microstructuring technique, is likely to provide a significant flexibility, cost effectiveness and even better parameters, if other material systems are considered.