High-Density Solenoid Inductor With Magnetic Film for Enhanced Performance in Silicon Interposer

Abstract

The 3-D inductor based on through silicon via (TSV) has been studied in the recent years due to its high density of integration and small footprint area. However, the TSV-based inductor suffers from a low-quality factor and small inductance density, owing to the severe loss in the silicon substrate at higher operating frequencies. This article proposes a novel 3-D inductor based on TSV with a core structure of magnetic film, which can improve the quality factor and inductance obviously. This article first optimizes the effect of controlling factors on the performance of conventional TSV-based inductor, including the length and radius of TSV, pitch between two loops, distance between grounding wire and TSV, dielectric liner [silicon dioxide (SiO2)] thickness, the number of turns, and the physical parameters of interconnect. Then, the effect of core physical parameters, dielectric constant, and thickness of magnetic film on the quality factor and inductance are revealed by the electromagnetic simulation. The novel inductor with optimized parameters and film-covered core structure can obtain a quality factor of 27.8 and a density of 115 nH/mm2, which has an improvement of 70% compared to the conventional inductor. Meanwhile, this article proposes a simple and compact physics-based model for the proposed inductor with high accuracy, which makes it easy to evaluate and optimize the performance of inductor. Finally, the conventional TSV-based inductors are fabricated to verify the accuracy of simulation results, and the errors between test results and electromagnetic simulation results are less than 5%.