Low resistance tunnel junctions with remote plasma underoxidized thick barriers

Low resistance tunnel junctions suitable for > 200 Gb/inch(2) read heads require R X A < 1 Omega mu m(2) and TMR > 10%, usually achieved by natural oxidation with tAl < 0.7 mri barriers. This paper shows that as-deposited junctions with competitive electrical and magnetic properties can be produced starting from 0.9 nm Al barriers and remote plasma oxidation in ion beam-deposited stacks using Co(73.8)Fe(16.2)B(10) electrodes. TMR similar to 20% for R X A similar to 2 -15 Omega mu m(2) is obtained, while in the R X A similar to 40 - 140 Omega mu m(2) range TMR can reach 40%-45%, in as-deposited samples. A limited number of junctions exhibits considerably lower R X A values with respect to the average while keeping similar MR (down to 0.44 Omega mu m(2) with 20% and down to 2.2 Omega mu m(2) with 51%). (c) 2005 American Institute of Physics.