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

采用同步三射频磁控溅射法制备了(CoFeB)-(SiO_2)、(CoFe)-(SiO_2)和CoFeB薄膜。获得了三种适用于1 GHz以上射频应用的薄膜，并对其磁导率特性和微观结构进行了研究。薄膜的磁导率具有较大的各向异性场H_k (40 ~ 550 Oe)，高铁磁共振（FMR）频率为1.6 ~ 6.0 GHz。它们还表现出非晶和纳米晶体结构，这使得它们具有良好的软磁性能，电阻率ρ为400-100,000 μΩcm，饱和磁化强度4ΠM_s为6.5-20 kG。较大的H_k和较高的电阻率有助于磁性器件以更低的损耗获得更高的频率特性。制备了含CoFeB金属磁性薄膜的杂化共面在线传输线。该器件由上下3μm厚的铝导体层和内（0.5 μm厚的聚酰亚胺）/ (0.5 μm厚的CoFeB) / （0.5 μm厚的聚酰亚胺）三层组成。顶部导体层由信号线和在同一平面上的接地面组成。CoFeB金属磁性膜在相同的热过程中，其静态相对磁导率约为180，FMR频率约为3.7 GHz。聚酰亚胺的相对介电常数约为3.5。结果表明，在所制备的器件中，在几兆赫频率处，波长缩短比约为0.19。在2 GHz时，四分之一波长器件的线长和插入损耗约为7 mm，约为2.9 dB。

(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.