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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100μm.采用4nm厚的Co75Fe25为铁磁电极和1·0或0·8nm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(5nm)/Cu(25nm)/Ni79Fe21(5nm)/Ir22Mn78(10nm)/Co75Fe25(4nm)/Al(0·8nm)-O/Co75Fe25(4nm)/Ni79Fe21(20nm)/Ta(5nm).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4μm×8μm—20μm×40μm、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.
The experimental and technological conditions for preparing the magnetic tunnel junction were optimized by using a metal mask method, the width of the slit of the metal mask was 100 μm, the thickness of Co75Fe25 with 4nm was used as the ferromagnetic electrode and the aluminum oxide with 1.0 or 0.8 nm (TMR) is 30% -48%. The structure of the magnetic tunnel junction is Ta (5nm) / Cu (25nm) / Ni79Fe21 (5nm) / Ir22Mn78 (10nm) / Co75Fe25 (4nm) / Al (0.8nm) -O / Co75Fe25 (4nm) / Ni79Fe21 (20nm) / Ta (5nm) .At the same time, using both lithography and lift- Ar ion beam etching and chemical reaction etching to prepare a high quality magnetic tunnel junction with high TMR and low resistance at room temperature of 4μm × 8μm-20μm × 40μm.The TMR of room temperature before and after 300 ℃ annealing can reach 22% and 50% .The research results show that the small size magnetic tunnel junction fabricated by the notch drilling or delamination lift-off process in photolithography can be used to develop the magnetoresistive unit of magnetic dynamic random access memory and magnetic read head and other sensing devices .