Headway Technologies, Incorporated

Magic Technologies, Inc.

Wang, Yu-jen

Kula, Witold

Jan, Guenole

Tong, Ru-ying

Ru Ying Tong

Guenole Jan

Witold Kula

Yu Jen Wang

Cheng Tzong Horng

Kochan Ju

Simon H Liao

You Feng Zheng

Min Li

Yu-Jen Wang

A MTJ for a spintronic device includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a free layer in a MTJ. Annealing between 300&#xb0; C. and 400&#xb0; C. may be used to further enhance PMA in the laminated layer.

Co/Ni multilayers with improved out-of-plane anisotropy for magnetic device applications

A MTJ for a domain wall motion device includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300&#xb0; C. and 400&#xb0; C. may be used to further enhance PMA in the laminated layer.

A MTJ for a spintronic device includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a reference layer in a MTJ. Annealing between 300&#xb0; C. and 400&#xb0; C. may be used to further enhance PMA in the laminated layer.

A MTJ for a spintronic device includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a dipole layer in a MTJ. Annealing between 300&#xb0; C. and 400&#xb0; C. may be used to further enhance PMA in the laminated layer.

A magnetic element is disclosed that has a composite free layer with a FM1/moment diluting/FM2 configuration wherein FM1 and FM2 are magnetic layers made of one or more of Co, Fe, Ni, and B and the moment diluting layer is used to reduce the perpendicular demagnetizing field. As a result, lower resistance x area product and higher thermal stability are realized when perpendicular surface anisotropy dominates shape anisotropy to give a magnetization perpendicular to the planes of the FM1, FM2 layers. The moment diluting layer may be a non-magnetic metal like Ta or a CoFe alloy with a doped non-magnetic metal. A perpendicular Hk enhancing layer interfaces with the FM2 layer and may be an oxide to increase the perpendicular anisotropy field in the FM2 layer. A method for forming the magnetic element is also provided.

Multilayers having reduced perpendicular demagnetizing field using moment dilution for spintronic applications

A magnetic element is disclosed wherein first and second interfaces of a free layer with a Hk enhancing layer and tunnel barrier, respectively, produce enhanced surface perpendicular anisotropy to lower switching current or increase thermal stability in a magnetic tunnel junction (MTJ). In a MTJ with a bottom spin valve configuration where the Hk enhancing layer is an oxide, the capping layer contacting the Hk enhancing layer is selected to have a free energy of oxide formation substantially greater than that of the oxide. The free layer may be a single layer or composite comprised of an Fe rich alloy such as CoFeB. With a thin free layer, the interfacial perpendicular anisotropy may dominate the shape anisotropy to generate a magnetization perpendicular to the planes of the layers. The magnetic element may be part of a spintronic device or serve as a propagation medium in a domain wall motion device.

Magnetic element with improved out-of-plane anisotropy for spintronic applications

A method for forming a MTJ in a spintronic device is disclosed and includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)composition. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300&#xb0; C. and 400&#xb0; C. may be used to further enhance PMA in the laminated layer.

A MTJ for a spintronic device is disclosed and includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)composition or the like where n is from 2 to 30. The seed layer is preferably NiCr, NiFeCr, Hf, or a composite thereof with a thickness from 10 to 100 Angstroms. Furthermore, a magnetic layer such as CoFeB may be formed between the laminated layer and a tunnel barrier layer to serve as a transitional layer between a (111) laminate and (100) MgO tunnel barrier. There may be a Ta insertion layer between the CoFeB layer and laminated layer to promote (100) crystallization in the CoFeB layer. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300&#xb0; C. and 400&#xb0; C. may be used to further enhance PMA in the laminated layer.

Enhanced Hc and Hk in addition to higher thermal stability to 400&#xb0; C. are achieved in magnetic devices by adding dusting layers on top and bottom surfaces of a spacer in a synthetic antiferromagnetic (SAF) structure to give a RL1/DL1/spacer/DL2/RL2 reference layer configuration where RL1 and RL2 layers exhibit perpendicular magnetic anisotropy (PMA), the spacer induces antiferromagnetic coupling between RL1 and RL2, and DL1 and DL2 are dusting layers that enhance PMA. RL1 and RL2 layers are selected from laminates such as (Ni/Co)n, L1alloys, or rare earth-transition metal alloys. The reference layer may be incorporated in STT-MRAM memory elements or in spintronic devices including a spin transfer oscillator. Dusting layers and a similar SAF design may be employed in a free layer for Ku enhancement and to increase the retention time of a memory cell.

High thermal stability reference structure with out-of-plane aniotropy to magnetic device applications

A magnetic element is disclosed that has a composite free layer with a FM1/moment diluting/FM2 configuration wherein FM1 and FM2 are magnetic layers made of one or more of Co, Fe, Ni, and B and the moment diluting layer is used to reduce the perpendicular demagnetizing field. As a result, lower resistance x area product and higher thermal stability are realized when perpendicular surface anisotropy dominates shape anisotropy to give a magnetization perpendicular to the planes of the FM1, FM2 layers. The moment diluting layer may be a non-magnetic metal like Ta or a CoFe alloy with a doped non-magnetic metal. A perpendicular Hk enhancing layer interfaces with the FM2 layer and may be an oxide to increase the perpendicular anisotropy field in the FM2 layer. The magnetic element may be part of a spintronic device or serve as a propagation medium in a domain wall motion device.

As the dimensions of spin valve heads continue to be reduced, a number of difficulties are being encountered. One such is with the longitudinal bias when an external magnetic field can cause reversal of the hard magnet, thereby causing a hysteric response by the head. This coercivity reduction becomes more severe as the hard magnet becomes thinner. This problem has been overcome by inserting a decoupling layer between the antiferromagnetic layer that is used to stabilize the pinned layer of the spin valve itself and the soft ferromagnetic layer that is used for longitudinal biasing. This soft ferromagnetic layer is pinned by a second antiferromagnetic layer deposited on it on its far side away from the first antiferromagnetic layer. The presence of the decoupling layer ensures that the magnetization of the soft layer is determined only by the second antiferromagnetic layer. The inclusion of said decoupling layer allows more latitude in etch depth control during manufacturing.

Ferromagnetic/antiferromagnetic bilayer, including decoupler, for longitudinal bias

As the dimensions of spin valve heads continue to be reduced, a number of difficulties are being encountered. One such is with the longitudinal bias when an external magnetic field can cause reversal of the hard magnet, thereby causing a hysteric response by the head. This coercivity reduction becomes more severe as the hard magnet becomes thinner. This problem has been overcome by inserting a decoupling layer between the antiferromagnetic layer that is used to stabilize the pinned layer of the spin valve itself and the soft ferromagnetic layer that is used for longitudinal biasing. This soft ferromagnetic layer is pinned by a second antiferromagnetic layer deposited on it on its far side away from the first antiferromagnetic layer. The presence of the decoupling layer ensures that the magnetization of the soft layer is determined only by the second antiferromagnetic layer. The inclusion of the decoupling layer allows more latitude in etch depth control during manufacturing.

A spin valve structure and a method for manufacturing it are described. The spin valve uses a modified pinned layer that consists of two cobalt iron layers separated by a layer of either ruthenium, iridium, or rhodium. A key feature of the invention is that this spacer layer is significantly thinner (typically 3-4 Angstroms) than similar layers in prior art structures. Normally, when such thin spacer layers are used, annealing fields in excess of 20,000 Oersted are needed to cause the two cobalt iron layers to become antiparallel. The present invention, however, teaches that much lower annealing fields (spanning a limited range) may be used with equal effect. The result is that a very high internal pinning field is created giving devices of this type greater pinned layer stability and reduced pinning reversal. These devices also exhibits a minimum amount of open looping in their hysteresis curves.

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Los Gatos, CA, United States of America

Ru Ying Tong