Novel on-chip spiral inductors with back hollow structure

Abstract

In this work, on-chip spiral inductors with back hollow structure have been prepared on the 500 [Formula: see text] thick silicon substrate with high resistivity [Formula: see text]. The silicon underneath the inductor region has been completely etched by deep etching process in order to reduce the substrate eddy current losses. Several types of square spiral on-chip inductors with different metal width (w) and line spacing (s) in the case of [Formula: see text] were fabricated. The experimental results are verified by FEM simulation using HFSS software. The results show that the Q-factor and self-resonance frequency of back hollow structure inductors are both enhanced compared with the conventional inductors. Furthermore, narrower width of coils for the on-chip spiral inductors with back hollow structure can result in higher Q-factor, inductance L and self-resonance frequency, which provide some important design guides for the fabrication of the high performance on-chip inductors.