- 學位論文
Co-M (M=Nb、Ta、Ta+B) 薄膜之製程參數與高頻軟磁特性之研究
Fabrication and soft magnetic properties of Co-M (M=Nb、Ta、Ta+B) thin film for high frequency application
摘要
本實驗採傾斜入射方式，並在濺鍍薄膜時外加1200 Oe磁場濺鍍Co-M系(M=Nb、Ta、Ta+B)合金薄膜，並研究薄膜高頻軟磁性、結構及電阻率。薄膜的鐵磁共振頻率與飽和磁化量(4πMs)和磁異向性場(Hk)相乘之平方根成正比，因此，高的飽和磁化量和高的磁異向性場為薄膜獲得高共振頻率的兩個必要條件。 本實驗第一部份研究濺鍍參數對Co93Nb7薄膜的影響。實驗結果顯示，隨著濺鍍功率增加，磁異向性場Hk有先升後降的趨勢。另一方面， Hk伴隨工作壓力增加呈現下降之趨勢。當濺鍍功率為150 W、工作壓力為0.5 mTorr時，有最佳4πMs (10.6 kG)，沿易磁化軸曲線矯頑磁力(Hce)為5.5 Oe，Hk=466 Oe，電阻率(ρ)=200 μΩ-cm，理論計算共振頻率(fFMR,cal.)為6.23 GHz。 本實驗第二部分研究Co100-xTax (x=0-24)薄膜。結果顯示Ta的添加皆會降低薄膜飽和磁化量及矯頑磁力，Hk在x=19時達到最大值。接著調變Co84Ta16薄膜之濺鍍參數。從實驗結果可發現，改變濺鍍參數時，Co-Ta系薄膜與Co-Nb系薄膜呈相似之磁特性表現。於125 W、0.5 mTorr時有最佳磁特性，4πMs=11.0 kG、Hce為10.8 Oe、Hk=617 Oe、電阻率ρ=170 μΩ-cm、fFMR,cal.=7.30 G Hz、fFMR,exp.=7.18 GHz。 最後以微量添加B於Co-Ta合金薄膜中，微量B會細化晶粒並有效降低矯頑磁力及提升其電阻率，然而微量B會降低薄膜之飽和磁化量及磁異向性場，導致其理論計算共振頻率大幅下降，其磁特性為4πMs=7.4 kG、Hce=5.1 Oe、Hk=493 Oe、ρ=183 μΩ-cm、fFMR,cal.=5.46 GHz。
並列摘要
The ferromagnetic resonance frequency (f FMR) of the magnetic thin film is proportional to the square root of the saturation magnetization (4πMs) and magnetic anisotropy field (Hk). High 4πMs and high Hk in the film are two crucial points for it to exhibit high f FMR for being the material for above giga hertz range applications. In this study, we prepared CoM (M=Nb、Ta、Ta+B) films by using the oblique deposition method with 1200 Oe external magnetic field during sputtering. At first, it was found that magnetic properties of Co93Nb7 are strongly dependent on sputtering parameters, including deposited power (PW) and working pressure (PAr). The magnetic anisotropy field Hk increased at first then decreased rapidly with increasing P. On the other hand, with decreased PAr, Hk is enhanced. Among them, Co93Nb7 thin film exhibits the optimal magnetic properties, where the 4πMs is 10.6 kG, Hce is 5.5 Oe, Hk is 466 Oe and fFMR is 6.23 GHz, as the power of sputtering is 150 W and the working pressure is kept at 0.5 mTorr. Secondly, the properties of high frequency of Co100-xTax (x=0-24) series films were studied. It was found that with increasing Ta content, the 4πMs, Hc and grain size all are decreased. The Hk reaches the peak when x=19. In addition, the magnetic behavior of Co-Ta films are similar to Co-Nb films, which strongly dependent on sputtering parameters. Among them, Co84Ta16 film exhibits the optimal magnetic properties, where the 4πMs is 11.0 kG, Hc is 10.8 Oe, Hk is 617 Oe, and fFMR is 7.18 GHz. Finally, B-added Co-Ta base thin films have been studied. The Hc decreased and resistivity enhanced by addition B. Nevertheless, 4πMs and Hk are decreased rapidly, resulting in the rapid decrease of fFMR. For B-added thin film, the 4πMs is 7.4 kG, Hce is 5.1 Oe, Hk is 496 Oe, ρ is 183 μΩ-cm and fFMR. cal is 5.46 GHz.