Authors: N. Chomnawang, H. Lu, K. Colinjivadi and J. Lee
Affilation: University of Texas at Dallas, United States
Pages: 392 - 395
Keywords: Inductor, simulation, high-aspect ratio, Q factor
We report the simulation work done by using Sonnet EMÔ on high aspect ratio (1:4 and 1:8) 3D on-chip air-core solenoid inductors. Simulations on 2, 3, and 5-turn inductors with 200 and 400 mm high vias have been completed. Materials used in the simulation are same as those of inductors previously fabricated by authors that use copper as inductors, silicon as a substrate, and silicon dioxide as an isolation layer. Simulation results show that high aspect ratio air-core solenoid inductors have relatively high Q factors (60 ~ 80) and inductances (1.0 ~ 3.5 nH). In our previous work, inductors were suspended in air with an assumption that air gap would enhance the RF performances. We investigated the effect by applying different dielectric materials including air, BCB (benzocylobutene), and spin-on glass that are used underneath the inductor to draw a conclusion if inductors suspended in air showed better RF performances than those sitting on common dielectric materials. Simulation results show that inductors suspended in air do provide better RF performances than those sitting on common dielectric materials, but the amount of improvement is only 7.1 % in Q factor and 9.8 % in SRF when compared to inductors sitting on spin-on-glass.