Abstract: A seed layer stack with a smooth top surface having a peak to peak roughness of about 0.5 nm over a range of 100 nm is formed by sputter depositing an X layer such as Mo on a Ni layer where the X layer has one or both of a larger bond energy and a greater atomic number than Ni. A (Ni/X)m laminate is formed and then an uppermost NiCr seed layer is deposited to enhance perpendicular magnetic anisotropy (PMA) in an overlying ferromagnetic layer. A <111> NiCr crystal structure promotes <111> texture in the ferromagnetic layer. X layers serve as a diffusion barrier to Ta migration from a bottom electrode and have good lattice matching with the adjoining Ni layer and uppermost NiCr layer. As a result of the smooth seed layer stack in a magnetic tunnel junction (MTJ), MTJ properties are improved and more reproducible.

Abstract: A seed layer stack with a smooth top surface having a peak to peak roughness of 0.5 nm is formed by sputter depositing an amorphous layer on a seed layer such as Mg where the seed layer has a resputtering rate 2 to 30× that of the amorphous layer. The uppermost seed layer is a template layer that is NiCr or NiFeCr. As a result, perpendicular magnetic anisotropy in an overlying magnetic layer that is a reference layer, free layer, or dipole layer is substantially maintained during high temperature processing up to 400° C. and is advantageous for magnetic tunnel junctions in embedded MRAMs, spintronic devices, or in read head sensors. The amorphous seed layer is SiN, TaN, or CoFeM where M is B or another element with a content that makes CoFeM amorphous as deposited. The seed layer stack may include a bottommost Ta or TaN buffer layer.

Abstract: A magnetic element is disclosed wherein a composite seed layer such as TaN/Mg enhances perpendicular magnetic anisotropy (PMA) in an overlying magnetic layer that may be a reference layer, free layer, or dipole layer. The first seed layer is selected from one or more of Ta, Zr, Nb, TaN, ZrN, NbN, and Ru. The second seed layer is selected from one or more of Mg, Sr, Ti, Al, V, Hf, B, and Si. A growth promoting layer made of NiCr or an alloy thereof is inserted between the seed layer and magnetic layer. In some embodiments, a first composite seed layer/NiCr stack is formed below the reference layer, and a second composite seed layer/NiCr stack is formed between the free layer and a dipole layer. The magnetic element has thermal stability to at least 400° C.

Abstract: A method for etching a magnetic tunneling junction (MTJ) structure is described. A stack of MTJ layers is provided on a bottom electrode in a substrate. The MTJ stack is etched to form a MTJ structure wherein portions of sidewalls of the MTJ structure are damaged by the etching. Thereafter, the substrate is removed from an etching chamber wherein sidewalls of the MTJ structure are oxidized. A physical cleaning of the MTJ structure removes damaged portions and oxidized portions of the MTJ sidewalls. Thereafter, without breaking vacuum, an encapsulation layer is deposited on the MTJ structure and bottom electrode.

Abstract: A magnetic element is disclosed wherein a composite seed layer such as TaN/Mg enhances perpendicular magnetic anisotropy (PMA) in an overlying magnetic layer that may be a reference layer, free layer, or dipole layer. The first seed layer is selected from one or more of Ta, Zr, Nb, TaN, ZrN, NbN, and Ru. The second seed layer is selected from one or more of Mg, Sr, Ti, Al, V, Hf, B, and Si. A growth promoting layer made of NiCr or an alloy thereof may be inserted between the seed layer and magnetic layer. The magnetic element has thermal stability to at least 400° C.

Abstract: 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)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: 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: 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: Synthetic antiferromagnetic (SAF) and synthetic ferrimagnetic (SyF) free layer structures are disclosed that reduce Ho (for a SAF free layer), increase perpendicular magnetic anisotropy (PMA), and provide higher thermal stability up to at least 400° C. The SAF and SyF structures have a FL1/DL1/spacer/DL2/FL2 configuration wherein FL1 and FL2 are free layers with PMA, the coupling layer induces antiferromagnetic or ferrimagnetic coupling between FL1 and FL2 depending on thickness, and DL1 and DL2 are dusting layers that enhance the coupling between FL1 and FL2. The SAF free layer may be used with a SAF reference layer in STT-MRAM memory elements or in spintronic devices including a spin transfer oscillator. Furthermore, a dual SAF structure is described that may provide further advantages in terms of Ho, PMA, and thermal stability.

Abstract: 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)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 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 spintronic device 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/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 STT-RAM MTJ is disclosed with a MgO tunnel barrier formed by natural oxidation and containing an oxygen surfactant layer to form a more uniform MgO layer and lower breakdown distribution percent. A CoFeB/NCC/CoFeB composite free layer with a middle nanocurrent channel layer minimizes Jc0 while enabling thermal stability, write voltage, read voltage, and Hc values that satisfy 64 Mb design requirements. The NCC layer has RM grains in an insulator matrix where R is Co, Fe, or Ni, and M is a metal such as Si or Al. NCC thickness is maintained around the minimum RM grain size to avoid RM granules not having sufficient diameter to bridge the distance between upper and lower CoFeB layers. A second NCC layer and third CoFeB layer may be included in the free layer or a second NCC layer may be inserted below the Ru capping layer.

Abstract: A method of forming 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 annealing 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: Synthetic antiferromagnetic (SAF) and synthetic ferrimagnetic (SyF) free layer structures are disclosed that reduce Ho (for a SAF free layer), increase perpendicular magnetic anisotropy (PMA), and provide higher thermal stability up to at least 400° C. The SAF and SyF structures have a FL1/DL1/spacer/DL2/FL2 configuration wherein FL1 and FL2 are free layers with PMA, the coupling layer induces antiferromagnetic or ferrimagnetic coupling between FL1 and FL2 depending on thickness, and DL1 and DL2 are dusting layers that enhance the coupling between FL1 and FL2. The SAF free layer may be used with a SAF reference layer in STT-MRAM memory elements or in spintronic devices including a spin transfer oscillator. Furthermore, a dual SAF structure is described that may provide further advantages in terms of Ho, PMA, and thermal stability.

Abstract: Synthetic antiferromagnetic (SAF) and synthetic ferrimagnetic (SyF) free layer structures are disclosed that reduce Ho (for a SAF free layer), increase perpendicular magnetic anisotropy (PMA), and provide higher thermal stability up to at least 400° C. The SAF and SyF structures have a FL1/DL1/spacer/DL2/FL2 configuration wherein FL1 and FL2 are free layers with PMA, the coupling layer induces antiferromagnetic or ferrimagnetic coupling between FL1 and FL2 depending on thickness, and DL1 and DL2 are dusting layers that enhance the coupling between FL1 and FL2. The SAF free layer may be used with a SAF reference layer in STT-MRAM memory elements or in spintronic devices including a spin transfer oscillator. Furthermore, a dual SAF structure is described that may provide further advantages in terms of Ho, PMA, and thermal stability.

Abstract: A method of forming 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 annealing 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 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 reference layer. The HOCL has an interface oxide layer adjoining the reference 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 reference layer.

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 reference layer. The HOCL has an interface oxide layer adjoining the reference 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 reference layer.