. This paper focuses on full integration of passive devices, especially inductors with emphasis on multi-layer stacked (MLS) structures of fully integrated inductors using patterned ground shield (PGS) and fully integrated capacitor. Comparison of diﬀerent structures is focused on the main electrical parameters of integrated inductors (e.g. inductance 𝐿 , inductance density 𝐿 𝐴 , quality factor 𝑄 , frequency of maximum quality factor 𝐹 𝑄 max , self-resonant frequency FSR, and series resistance 𝑅 DC ) and other non-electrical parameters (e.g. required area, manufacturing process, purpose, etc.) that are equally important during comparison of the structures. Categorization of inductor structures with most signiﬁcant results that was reported in the last years is proposed according to manufacturing process. Final geomet-rical and electrical properties of the structure in great man-ner accounts to the fabrication process of integrated passive device. This work oﬀers an overview and state-of-the-art of the integrated inductors as well as manufacturing processes used for their fabrication. Second purpose of this paper is insertion of the proposed structure from our previous work among the other results reported in the last 7 years. With the proposed solution, one can obtain the highest inductance density 𝐿 𝐴 = 23.59 nH/mm 2 and second highest quality factor 𝑄 = 10.09 amongst similar solutions reported in standard technologies that is also suitable competition for integrated inductors manufactured in advanced technology nodes.

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An Overview of Fully On-Chip Inductors

This paper presents an overview and State-of-the-Art of fully integrated inductors with common fabrication processes used for implementation of these structures into a chip. The first step is an overview of fabrication technologies that starts with standard CMOS general purpose processes expanded by Far-BEOL and substrate alteration process (SOI, Silicon Embedded, TSV, TGV, PTH, Core Insertion); and continues to advanced process nodes like SMMT and Bond Wire utilization. Then, an overview of fully integrated inductor structures consists of selected topologies with notable parameters achieved in last few years. Critical parameters of integrated inductors include: inductance L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</inf> , inductance density LA, quality factor Q, self-resonant frequency FSR and series resistance R <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DC</inf> . These parameters are as important as the purpose and fabrication process. 

Fully Integrated On-Chip Inductors: An Overview

In this work, we propose a Ni-Zn ferrite core embedding process in a photosensitive glass substrate and demonstrate the design and fabrication of substrate embedded inductors and integrated voltage regulators (IVRs) using the substrate embedded ferrite cores. We developed a ferrite core embedding process inside a vertical cavity of a photosensitive glass substrate, so that ferrite core solenoid inductors can be embedded in the substrate. The measured inductance, DC resistance and Q-factor of a 1600μm × 1500μm ferrite core inductor were 209nH, 240mOhm, 15.8 at 18.2Mhz respectively. And a 920μm × 1050μm inductor has inductance of 252nH, DC resistance of 663mOhm, and Q-factor of 16.6 at 20Mhz. The power conversion efficiency of an integrated voltage regulator module was measured up to 85.2%.

Insub Han

Papers

Demonstration of Substrate Embedded Ni-Zn Ferrite Core Solenoid Inductors Using a Photosensitive Glass Substrate