摘要:
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.
摘要:
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, 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.
摘要:
An STT MTJ cell is formed with a magnetic anisotropy of its free and reference layers that is perpendicular to their planes of formation. The reference layer of the cell is an SAF multilayered structure with a single magnetic domain to enhance the bi-stability of the magnetoresistive states of the cell. The free layer of the cell is etched back laterally from the reference layer, so that the fringing stray field of the reference layer is no more than 15% of the coercivity of the free layer and has minimal effect on the free layer.
摘要:
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.
摘要:
An all (111) MTJ stack is disclosed in which there are no transitions between different crystalline orientations when going from layer to layer. This is accomplished by providing strongly (111)-textured layers immediately below the MgO tunnel barrier to induce a (111) orientation therein.
摘要:
A magnetic element in a spintronic device or serving as a propagation medium in a domain wall motion device is disclosed wherein first and second interfaces of a free layer with a perpendicular Hk enhancing layer and tunnel barrier, respectively, produce enhanced surface perpendicular anisotropy to increase thermal stability in a magnetic tunnel junction. The free layer may be a single layer or a composite and is comprised of a glassing agent that has a first concentration in a middle portion thereof and a second concentration less than the first concentration in regions near first and second interfaces. A CoFeB free layer selectively crystallizes along first and second interfaces but maintains an amorphous character in a middle region containing a glass agent providing the annealing temperature is less than the crystallization temperature of the middle region.
摘要:
An all (111) MTJ stack is disclosed in which there are no transitions between different crystalline orientations when going from layer to layer. This is accomplished by providing strongly (111)-textured layers immediately below the MgO tunnel barrier to induce a (111) orientation therein.
摘要:
A boron or boron containing dusting layer such as CoB or FeB is formed along one or both of top and bottom surfaces of a free layer at interfaces with a tunnel barrier layer and capping layer to improve thermal stability while maintaining other magnetic properties of a MTJ stack. Each dusting layer has a thickness from 0.2 to 20 Angstroms and may be used as deposited, or at temperatures up to 400° C. or higher, or following a subsequent anneal at 400° C. or higher. The free layer may be a single layer of CoFe, Co, CoFeB or CoFeNiB, or may include a non-magnetic insertion layer. The resulting MTJ is suitable for STT-MRAM memory elements or spintronic devices. Perpendicular magnetic anisotropy is maintained in the free layer at temperatures up to 400° C. or higher. Ku enhancement is achieved and the retention time of a memory cell for STT-MRAM designs is increased.
摘要:
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. 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.
摘要:
A STT-RAM MTJ is disclosed with a MgO tunnel barrier formed by natural oxidation process. A Co10Fe70B20/NCC/Co10Fe70B20, Co10Fe70B20/NCC/Co10Fe70B20/NCC, or Co10Fe70B20/NCC/Co10Fe70B20/NCC/Co10Fe70B20 free layer configuration where NCC is a nanocurrent channel layer made of Fe(20%)-SiO2 is used to minimize Jc0 while enabling higher thermal stability, write voltage, read voltage, Ho, and Hc values that satisfy 64 Mb design requirements. The NCC layer is about 10 Angstroms thick to match the minimum Fe(Si) grain diameter size. The MTJ is annealed with a temperature of about 330° C. to maintain a high magnetoresistive ratio while maximizing Hk⊥(interfacial) for the free layer thereby reducing Heff and lowering the switching current. The Co10Fe70B20 layers are sputter deposited with a low pressure process with a power of about 15 Watts and an Ar flow rate of 40 standard cubic centimeters per minute to lower Heff for the free layer.