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中国物理学会期刊

高磁电阻磁性隧道结的几种微制备方法研究

CSTR: 32037.14.aps.54.3831

Microfabrication methods of magnetic tunnel junctions with high tunneling magnetoresistance

CSTR: 32037.14.aps.54.3831
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  • 利用金属掩模法优化了制备磁性隧道结的实验和工艺条件,金属掩模的狭缝宽度为100 μm. 采用4 nm厚的Co75Fe25为铁磁电极和10或08 nm厚的铝氧化物 为势垒膜, 直接制备出了室温隧穿磁电阻(TMR)为30%—48%的磁性隧道结,其结构为Ta(5 nm)/Cu(25 nm)/Ni79Fe21(5 nm)/Ir22Mn78(10 nm)/ Co75Fe25 (4 nm)/Al(08 nm)-O/Co75Fe25(4 nm)/Ni79Fe 21(20 nm)/Ta(5 nm).同时,利用刻槽打孔法和去胶掀离法两种光刻技术并结合Ar离子束刻蚀及化学反应刻 蚀,制备出面积在4 μm×8 μm—20 μm×40 μm、具有室温高TMR和低电阻的高质量磁性 隧道结.300 ℃ 退火前后其室温TMR可分别达到22% 和50%.研究结果表明,采用光刻中的刻 槽打孔或去胶掀离工艺方法制备的小尺寸磁性隧道结,可用于研制磁动态随机存储器和磁读 出头及其他传感器件的磁敏单元.

     

    In this work, on the one hand, the contact-shadow-mask method and technique were used to micro-fabricate the magnetic tunnel junction (MTJ) and optimize the experimental conditions. The width of the gap for the long and narrow top or bottom magneto-electrode is 100 μm, which can be used to deposit MTJs and form a cross strip with the tunnel section of 100 μm×100 μm. The MTJs with tunneling magnetoresistance (TMR) ratio of 30%—48% can be directly obtained for the structure of Ta(5 nm)/Cu(25 nm)/Ni79Fe21(5 nm)/Ir22Mn78(10 nm)/Co75Fe25(4 nm)/Al(08 nm)-O/Co75Fe25(4 nm)/Ni79Fe21(20 nm)/Ta(5 nm). On the other hand, t he MTJs with high TMR ratio and small active area from 20 μm×40 μm down to 4 μm×8 μm were fabricated using two optical lithography methods of milling contact hole and lift-off resist, combined with Ar ion-beam etching or CF4 reactive etching technique s. Then, the TMR ratio from 22% up to 50% can be achieved before and after annealing at around 300 ℃ for 1 h. Our investigation shows that the patterned MTJs, which were microfabricated using the two optical lithography methods stated above, can b e used as the fundamental element of magnetoresistive random access memory, magn etic read-heads in hard disk drives and the field sensitive sensor.

     

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