Review of MEMS inductors for integrated DC-DC converters

• Main Author: Ling, Yuchen
• Other Authors: Gwee Bah Hwee
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2022
• Subjects: Engineering::Electrical and electronic engineering
• Online Access: https://hdl.handle.net/10356/158141
• Institution: Nanyang Technological University

This report pertains to miniature inductors for integrated switched-mode inductive DC-DC converters applications. Conventional inductive DC-DC converters generally employ external discrete inductor components that are bulky and expensive, thereby increasing the overall form-factor (size) and cost. On the other hand, current-art integrated inductive DC DC converters integrate the inductors as in-package or on-chip components to decrease the form-factor and cost. This report investigates state-of-the-art on-chip integrated inductors that are fabricated with microelectromechanical system (MEMS) technology. Compared to conventional on-chip inductors realized using CMOS technology, MEMS inductors can achieve higher quality factor and higher inductance required for integrated DC-DC converters, and they are also relatively easy to integrate with the on-chip CMOS circuitries. There are three pertinent aspects pertaining to MEMS integrated inductors that are reviewed comprehensively in this report: one is the established MEMS fabrication processes; two is the magnetic cores of the inductors; three is the structures of the inductors. On the fabrication processes, this report reviews two well-established processes—the bulk and the surface micromachining. On the magnetic cores, this report reviews the core materials and their effects on the magnetic losses. On the structures, this report reviews three conventional and state-of-the-art structures—the 2D planar, the 3D on-sub, and the in-sub TSV.