Open AccessMicrofabrication methods of magnetic tunnel junctions with high tunneling magnetoresistance
Author(s) -
Feifei Li,
Xiequn Zhang,
Du Guan-Xiang,
Tianxing Wang,
Zeng Zhong-Ming,
Wei Hong-Xiang,
Xiufeng Han
Publication year - 2005
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.54.3831
Subject(s) - materials science , magnetoresistance , ion milling machine , quantum tunnelling , annealing (glass) , electrode , shadow mask , etching (microfabrication) , patterned media , optoelectronics , permalloy , magnetic field , nanotechnology , magnetization , optics , grain size , composite material , physics , quantum mechanics , chemistry , layer (electronics)
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(08 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.