title: Annealing Stability Study of Co20Fe60B20\MgO\ Co20Fe60B20Perpendicular Magnetic Tunnel Junctions.
abstract: A full Co20Fe60B20\MgO\ Co20Fe60B20perpendicular magnetic tunnel junction (pMTJ) with (Co\Pt) multilayers as pinning layers and different functional multilayers stacks were made and annealed at different temperatures. The tunneling magnetoresistance ratio (TMR) and MgO barrier resistance-area product (RA) were measured and analyzed as a function of annealing temperature. The TMR of pMTJs dramatically declines with increasing annealing temperatures from 320 °C to 400 °C while the RA increases with temperature from 375 °C to 450 °C. The pMTJs and partial stacks were also measured in a vibrating sample magnetometer (VSM). We found that the (Co\Pt) multilayers are very stable and maintain a magnetization direction perpendicular to the film plane up to 450 °C. However, the magnetization direction of the CoFeB above and below the MgO barrier rotates from perpendicular to in-plane with increasing annealing temperature. Furthermore, the CoFeB layer influences the adjacent (Co\Pt) layers to rotate at the same time. The pMTJs' elemental depth profiles in the as deposited and annealed states were determined by Secondary Ion Mass Spectrometry (SIMS). We found that Boron and Tantalum migrate towards the top of the stack. The other elements (Platinum, Cobalt, Ruthenium, and Magnesium) are very stable and do not interdiffuse during annealing up to 450°C.
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8552; Theiss Research, 7411 Eads Ave.La Jolla, CA 92037.
authors.forename: P J
authors.initials: PJ
authors.lastname: Chen
authors.affiliation: Colleges of Nanoscale Science & Engineering, SUNY Polytechnic Institute, Albany, NY 12203.
authors.forename: M
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Singulus Technologies AG, 63796 Kahl am Main, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Tibus
authors.affiliation: SEMATECH Inc., 257 Fuller Rd., Albany, NY 12203.
authors.forename: T
authors.initials: T
authors.lastname: Dyer
authors.affiliation: Colleges of Nanoscale Science & Engineering, SUNY Polytechnic Institute, Albany, NY 12203.
authors.forename: J
authors.initials: J
authors.lastname: Piccirillo
authors.affiliation: Singulus Technologies AG, 63796 Kahl am Main, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Ocker
authors.affiliation: National Institute of Standards and Technology, Gaithersburg, MD 20899-8552.
authors.forename: R D
authors.initials: RD
authors.lastname: Shull