Developments of GHz and heterro-amorphous inductor core materials for integrated circuit

采用同步三重射频磁控溅射方法，旋转圆柱形电极，制备了(CoFeB)-(SiO_2)、(CoFe)-(SiO_2)和CoFeB薄膜。获得了3种用于1 GHz以上射频应用的薄膜，并对它们的磁导率特性和微结构进行了研究，薄膜在40~550 Oe范围内表现出较大的各向异性场Hk，磁导率特性的铁磁共振(FMR)频率为1.6~6.0 GHz。它们还具有非晶态和纳米晶结构，具有良好的软磁性能，其电阻率ρ为400-100,000μΩcm，饱和磁化强度4ΠM_S为6.5-20 kg。较大的Hk和较高的电阻率是获得较高频率特性和较低损耗的有效方法。研制了一种CoFeB金属磁性薄膜混合薄膜共面传输线。器件由上下3μm厚的铝导体层和内层(0.5μm厚的聚酰亚胺)/(0.5μm厚的CoFeB)/(0.5μm厚的聚酰亚胺)三层组成。顶导体层由同一平面上的信号线和地平面组成。CoFeB金属磁性薄膜的静态相对磁导率约为180，铁磁共振频率约为3.7 GHz。聚酰亚胺的相对介电常数约为3.5，制备的器件在几吉赫兹频率下的波长缩短率约为0.19。1/4波长器件的线长和插入损耗估计在2 GHz时约为7 mm和2.9db。

(CoFeB)-(SiO_2), (CoFe)-(SiO_2) and CoFeB films were fabricated by synchronous triple rf magnetron sputtering while rotating a cylindrical electrode. Three types of films for rf application in the range over 1 GHz were obtained, and their permeability characteristics and micro-structures were investigated.The films exhibited large anisotropy fields H_k in the range from 40 to 550 Oe, and high ferromagnetic resonance (FMR) frequencies of 1.6-6.0 GHz in permeability characteristics. They also exhibited amorphous and nano-crystal structures, which led to good soft magnetic properties with electrical resistivities ρ of 400-100,000 μΩcm and saturation magnetizations 4ΠM_s of 6.5-20 kG. The larger H_k and higher resistivities obtained were effective for attaining the higher-frequency characteristics with lower losses for magnetic devices.A hybrid thin film coplanar transmission-line with a CoFeB metallic magnetic film was fabricated and estimated. The fabricated devices consisted of top and bottom 3μm-thick aluminum conductor layers and inner (0.5 μm-thick Polyimide) / (0.5 μm-thick CoFeB) / (0.5 μm-thick Polyimide) trilayer. The top conductor layer consisted of a signal line and ground planes on the same plane. The CoFeB metallic magnetic film, exposed to the same thermal process of the device fabrication, had a static relative permeability of about 180 and FMR frequency of about 3.7 GHz. The Polyimide had a relative permittivity of about 3.5.As a result, a wavelength shortening ratio of the fabricated device was about 0.19 at a few gigahertzes in frequency. The line length and the insertion loss of a quarter-wavelength device were estimated to be about 7 mm and about 2.9 dB at 2 GHz.