Development of GHz-Drive Magnetic Thin Film Inductors for Integrated Circuits

本文提出了一种新的GHz波段磁导元件，以寻找可能用作GHz驱动电感的CoNbZr、FeAlO和（CoFeB）SiO_2薄膜材料。提出了一种提高铁磁共振频率的新技术：沿着易磁化轴微加工窄缝，沿着难磁化轴施加稀土磁场。在2GHz下，采用最佳狭缝设计方法，可以忽略2GHz下的磁损耗，并在顶部沉积0.1-1.0μ m厚的CoNbZr薄膜，制作出了尺寸为330 × 330 μm^2的集成螺旋电感，在2GHz下，L= 8 nH，Q=5。如果在螺旋线圈（三明治型电感）的上下两侧都安装有沉积的CoNbZr磁性薄膜，则在200 × 400 μm^2的尺寸下，L=7.9nH，Q=13。研制了一种稀土近场磁探针，用于分析集成电感到半导体电路的漏磁。该探头在1GHz时具有世界最高的空间分辨率，达到40μm。集成铁磁薄膜可以广泛地应用于通过铁磁电阻损耗来抑制射频同轴电磁噪声。在1GHz时，插入损耗仅为0.4dB，而在20 GHz时，插入损耗达到15 dB。因此，本工作为铁磁集成电感的实际应用提供了可能性，并开拓了一个新的技术领域“GHz范围内的IT软磁应用”。第一届和第二届“高频微磁器件与材料”国际研讨会已由研究人员发起。

A new GHz-band permeameter has been developed to find out the CoNbZr, FeAlO and (CoFeB)SiO_2 Thin-film materials as the possible candidates for GHz-drive inductors. A new technique on raise the ferromagnetic resonance (FMR) frequency has also been developed; Microfabricate narrow slits along the easy axis of magnetization and apply RE magnetic field along the hard axis. Then magnetic losses at 2GHz can be negligible through the optimum slit design method we established.An integrated spiral inductor with 0.1-1.0μm-thick silted CoNbZr film on the top exhibited L=8nH and Q=5 at 2GHz, Its size was 330x330μm^2. Provided that the silted CoNbZr magnetic film are installed below and on the spiral (sandwich type inductor), L=7.9nH and Q=13 has been achieved is the 200x400μm^2 size. This is worth achieving main objective of this work.An RE magnetic near field probe has been developed to analyze leakage flux from the integrated inductor to semiconductor circuit. The probe exhibited world-highest spatial resolution of 40μm at 1GHz. It is estimated that the electromagnetic interference to the integrated circuit would be negligible.An extensive application of integrated ferromagnetic film has been proposed to suppress RF in-line electromagnetic noise by means of FMR losses. Insertion loss at 1GHz was only 0.4dB while is reached 15dB as 20GHz.Thus this work has been concluded, showing a practical possibility of ferromagnetic integrated inductors as well as to pioneering a new technology field of "soft magnetic applications in the GHz range for IT." The first and second international symposium on "High Frequency Micromagnetic Devices and Materials" has been initiated by the investigators.