Abstract: A method of forming a MTJ with a tunnel barrier having a high tunneling magnetoresistance ratio, and low resistance x area value is disclosed. The method preserves perpendicular magnetic anisotropy in bottom and top magnetic layers that adjoin bottom and top surfaces of the tunnel barrier. A key feature is a passive oxidation step of a first Mg layer that is deposited on the bottom magnetic layer wherein a maximum oxygen pressure is 10?5 torr. A bottom portion of the first Mg layer remains unoxidized thereby protecting the bottom magnetic layer from substantial oxidation during subsequent oxidation and anneal processes that are employed to complete the fabrication of the tunnel barrier and MTJ. An uppermost Mg layer may be formed as the top layer in the tunnel barrier stack before a top magnetic layer is deposited.

Abstract: A hybrid oxide capping layer (HOCL) is disclosed and used in a magnetic tunnel junction to enhance thermal stability and perpendicular magnetic anisotropy in an adjoining free layer. The HOCL has a lower interface oxide layer and one or more transition metal oxide layers wherein each of the metal layers selected to form a transition metal oxide has an absolute value of free energy of oxide formation less than that of the metal used to make the interface oxide layer. One or more of the HOCL layers is under oxidized. Oxygen from one or more transition metal oxide layers preferably migrates into the interface oxide layer during an anneal to further oxidize the interface oxide. As a result, a less strenuous oxidation step is required to initially oxidize the lower HOCL layer and minimizes oxidative damage to the free layer.

Abstract: A synthetic antiferromagnet serving as a reference layer for a magnetic tunnel junction is a laminate with a plurality of “x+1” magnetic sub-layers and “x” non-magnetic spacers arranged in an alternating fashion, with a magnetic sub-layer at the top and bottom of the laminated stack. Each spacer has a top and bottom surfaces that interface with adjoining magnetic sub-layers generating antiferromagnetic coupling between the adjoining sub-layers. Perpendicular magnetic anisotropy is induced in each magnetic sub-layer through an interface with a spacer. Thus the dipole field exerted on a free layer is substantially reduced compared with that produced by a conventional synthetic antiferromagnetic reference layer. Magnetic sub-layers are preferably Co while Ru, Rh, or Ir may serve as non-magnetic spacers.

Abstract: 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.

Abstract: 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 Co20Fe60B20. 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.

Abstract: 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/X)n or (CoX)n? composition where n is from 2 to 30, X is one of V, Rh, Ir, Os, Ru, Au, Cr, Mo, Cu, Ti, Re, Mg, or Si, and CoX is a disordered alloy. 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. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: 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/X)n or (CoX)n composition where n is from 2 to 30, X is one of V, Rh, Ir, Os, Ru, Au, Cr, Mo, Cu, Ti, Re, Mg, or Si, and CoX is a disordered alloy. 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. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: A MTJ for a spintronic device that is a domain wall motion device is disclosed and includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/X)n or (CoX)n composition where n is from 2 to 30, X is one of V, Rh, Ir, Os, Ru, Au, Cr, Mo, Cu, Ti, Re, Mg, or Si, and CoX is a disordered alloy. 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. The laminated layer may be used as a reference layer, dipole layer, or free layer in a MTJ. Annealing between 300° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: A MTJ is disclosed with a discontinuous Mg or Mg alloy layer having a thickness from 1 to 3 Angstroms between a free layer and a capping layer in a bottom spin valve configuration. It is believed the discontinuous Mg layer serves to block conductive material in the capping layer from diffusing through the free layer and into the tunnel barrier layer thereby preventing the formation of conductive channels that function as electrical shunts within the insulation matrix of the tunnel barrier. As a result, the “low tail” percentage in a plot of magnetoresistive ratio vs Rp is minimized which means the number of high performance MTJ elements in a MTJ array is significantly increased, especially when a high temperature anneal is included in the MTJ fabrication process. The discontinuous layer is formed by a low power physical vapor deposition process.

Abstract: 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)n 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° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: A MTJ for a domain wall motion device is disclosed and includes a thin seed layer that enhances perpendicular magnetic anisotropy (PMA) in an overlying laminated layer with a (Co/Ni)n 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° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: 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)n 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° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: 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)n 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° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: A multi-layered bottom electrode for an MTJ device on a silicon nitride substrate is described. It comprises a bilayer of alpha tantalum on ruthenium which in turn lies on a nickel chrome layer over a second tantalum layer.

Abstract: Enhanced Hc and Hk in addition to higher thermal stability to 400° 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. Dusting layers are deposited at room temperature to 400° C. RL1 and RL2 layers are selected from laminates such as (Ni/Co)n, L10 alloys, 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. A transition layer such as CoFeB/Co may be formed between the RL2 reference layer and tunnel barrier layer in a bottom spin valve design.

Abstract: 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)n 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° C. and 400° C. may be used to further enhance PMA in the laminated layer.

Abstract: Enhanced Hc and Hk in addition to higher thermal stability up to at least 400° 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. Dusting layers are deposited at room temperature to 400° C. RL1 and RL2 layers are selected from laminates such as (Ni/Co)n, L10 alloys, 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 for STT-MRAM designs.

Abstract: A hybrid oxide capping layer (HOCL) is disclosed and used in a magnetic tunnel junction to enhance thermal stability and perpendicular magnetic anisotropy in an adjoining free layer. The HOCL has a lower interface oxide layer and one or more transition metal oxide layers wherein each of the metal layers selected to form a transition metal oxide has an absolute value of free energy of oxide formation less than that of the metal used to make the interface oxide layer. One or more of the HOCL layers is under oxidized. Oxygen from one or more transition metal oxide layers preferably migrates into the interface oxide layer during an anneal to further oxidize the interface oxide. As a result, a less strenuous oxidation step is required to initially oxidize the lower HOCL layer and minimizes oxidative damage to the free layer.

Abstract: A synthetic antiferromagnetic (SAF) structure for a spintronic device is disclosed and has an FL2/AF coupling/CoFeB configuration where FL2 is a ferromagnetic free layer with intrinsic PMA. In one embodiment, AF coupling is improved by inserting a Co dusting layer on top and bottom surfaces of a Ru AF coupling layer. The FL2 layer may be a L10 ordered alloy, a rare earth-transition metal alloy, or an (A1/A2)n laminate where A1 is one of Co, CoFe, or an alloy thereof, and A2 is one of Pt, Pd, Rh, Ru, Ir, Mg, Mo, Os, Si, V, Ni, NiCo, and NiFe, or A1 is Fe and A2 is V. A method is also provided for forming the SAF structure.

Abstract: An improved PMA STT MTJ storage element, and a method for forming it, are described. By inserting a suitable oxide layer between the storage and cap layers, improved PMA properties are obtained, increasing the potential for a larger Eb/kT thermal factor as well as a larger MR. Another important advantage is better compatibility with high processing temperatures, potentially facilitating integration with CMOS.