Silicon-based Ultimate Miniature Magnetic Inductors Technology for High-efficiency DC-DC Conversion

This paper presents the development of high frequency (> 10MHz) silicon-based thin-film magnetic- core inductors for DC-DC converter applications with high conversion efficiency. These inductors were fabricated with far-BEOL compatible process on 300 mm wafers. With an improved laminated thinfilm magnetic core and thick electro-plated Cu windings, these inductors achieved a wide range of inductance ranging from 10 to 250nH, a high Q factor of up to 17, and a saturation current of up to 650 mA in a small area of 1mm(2). These inductor properties translate to more than 90% inductor power efficiency in a multiple-phased 3.6V-to-1V DC-DC converter within a current range of 0.1A to 1A.