A Fully Integrated Thin-Film Inductor and Its Application to a DC-DC Converter

ETRI Journal

关键词: NiFe core;    DC-DC converter;    thin-film inductor;    Process integration;   

Others  :  1184811
DOI  :  10.4218/etrij.03.0202.0404

【 摘 要 】

This paper presents a simple process to integrate thin-film inductors with a bottom NiFe magnetic core. NiFe thin films with a thickness of 2 to 3 m were deposited by sputtering. A polyimide buffer layer and shadow mask were used to relax the stress of the NiFe films. The fabricated double spiral thin-film inductor showed an inductance of 0.49 H and a Q factor of 4.8 at 8 MHz. The DC-DC converter with the monolithically integrated thin-film inductor showed comparable performances to those with sandwiched magnetic layers. We simplified the integration process by eliminating the planarization process for the top magnetic core. The efficiency of the DC-DC converter with the monolithic thin-film inductor was 72% when the input voltage and output voltage were 3.5 V and 6 V, respectively, at an operating frequency of 8 MHz.

   

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