Monolithic double rectangular spiral thin-film inductors implemented with NiFe magnetic cores for on-chip dc–dc converter applications

• Published in: Thin solid films Vol. 517; no. 14; pp. 4204 - 4206
• Main Authors: Kim, Sang Gi, Park, Hoon Soo, Koo, Jin Gun, Kim, Jong Dae, Rho, Tae Moon, Lee, Yong Hyun, Kim, Bo Woo, Kang, Jin Yeong
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 29-05-2009; Elsevier
• Subjects: Applied sciences; dc–dc converter; Electronics; Exact sciences and technology; NiFe magnetic core; Optoelectronic devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Thin-film inductor; dc–dc converter; NiFe magnetic core; Thin-film inductor; Polyimide; Semiconductor materials; dc-dc converter; Q factor; Iron alloy; Chip; Photodetector; Thin film; Thick film; Copper; Nickel alloy
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2009.02.019

This paper describes a simple, on-chip complimentary metal oxide semiconductor (CMOS) compatible thin-film inductor applied for the dc–dc converters. The double rectangular spiral types of the thin-film inductors were implemented with 15 µm-thick copper films upon 2.5 µm thick of the NiFe magnetic core. Prior to fabricating a high-voltage CMOS dc–dc converter circuit, the NiFe magnetic core was deposited on the polyimide film. Adapting a double-rectangular structure, the fabricated monolithic inductor exhibited not only high inductance of 1.6 µH but also high quality factor of 11.2 at 5 MHz. To simplify the integration process, the planarization process for the top magnetic core was eliminated. The performance of the dc–dc converter which combined with our proposed inductors was evaluated at a high power efficiency of 81% when the converter operated at a frequency of 5 MHz corresponding to input and output voltages of 3.3 V and 8.1 V, respectively.