本論文是利用磁控濺鍍系統成長CoFeB/MgO/CoFeB垂直式磁穿隧結多層膜,而後進行磁滯曲線(M-H)的量測工作;再經由蝕刻將多層膜製作出5um*10um橢圓形元件並進行磁阻曲線(R-H)的量測工作。實驗主要分為三部分 (1)成長多層膜樣品J1 SiO2/Ta(5)/Ru(10)/Ta(5)/CoFeB(1.2)/MgO(1.5)/CoFeB(1.2)/Ta(5)/Ru(5) (in nm)在室溫M-H測量結果中觀察到我們的磁滯曲線是由一層垂直式鐵磁層與一層垂直式超順磁層所疊加而成的,我們進而量測磁阻曲線發現其磁阻曲線與Langevin Function類似,而Langevin Function的特性就是在零附近為線性的,我們利用此線性的特性來做為一個磁感應器。 除此之外,我們經由改變測量偏壓發現當偏壓越大時,磁阻率會下降,磁感應器的敏感度也會因磁阻率的下降而減少;而磁阻曲線的Hc也會因外加正或負的偏壓隨之增加或減少。 (2)低溫M-H測量結果發現當溫度低於220K以下,超順磁層因轉變為鐵磁層而出現磁滯的現象,隨著溫度的降低,兩磁滯間的反平行態越明顯。 (3)我們成長另外一組多層膜樣品SiO2/Ta(5)/Ru(10)/Ta(5)/CoFeB(1.2)/MgO(x)/CoFeB(1.2)/Ta(1) (in nm) F1(x=2)及I1(x=1.3)。對此兩組樣品也分別施加不同偏壓作量測,發現兩組樣品皆有場效應的現象,其中MgO厚度為2nm樣品F1較MgO厚度為1.3nm樣品I1場效應現象來的明顯。
A magnetoresistor field sensor usually consists of two ferromagnetic layers with orthogonal anisotropy in a tunnel magnetoresistance structure. In this thesis, we use ultrathin CoFeB/MgO/CoFeB junction with ferromagnetic-superparamagnetic coupling and introduce a new type magnetoresistor field sensor. The Multilayered structure of SiO2/Ta(5)/Ru(10)/Ta(5)/CoFeB(1.2)/MgO(1.5)/CoFeB(1.2)/Ta(5)/Ru(5) (in nm) is fabricated by sputtering. The characterization of the magnetoresistance curve with a Langevin function and strong bias voltage effect of these sensors are investigated. The sensitivity of this sensor is also compared with the conventional orthogonal sensor.