# US 10,374,147 B2 · Perpendicular magnetic tunnel junction having improved reference layer stability > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,147 B2 - Document ID: US10374147B2 - Status: Granted - Kind: B2 - Application number: 15/859,460 - Filed: 2017-12-30 - Published: 2019-07-04 - Granted: 2019-08-06 - Earliest claimed: 2017-12-30 - Assignees: Spin Memory, Inc. - Applicants: Spin Memory, Inc. - Inventors: Mustafa Pinarbasi; Bartlomiej Adam Kardasz; Jorge Vasquez; Manfred Ernst Schabes - Web page: https://patentgrep.com/patent/US10374147B2 ## CPC - H10N 50/80: Constructional details - G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell} - G11C 11/1675: {Writing or programming circuits or methods} - H01F 10/3254: {the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]} - H01F 10/3286: {Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy} - H01F 10/329: {Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect} - H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices - H10N 50/10: Magnetoresistive devices - H10N 50/85: Materials of the active region - H01F 10/3272: {by use of anti-parallel coupled [APC] ferromagnetic layers, e.g. artificial ferrimagnets [AFI], artificial [AAF] or synthetic [SAF] anti-ferromagnets} - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - G11C: STATIC STORES (semiconductor memory devices H10B) - H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES - H10B: ELECTRONIC MEMORY DEVICES ## Abstract A magnetic data recording element for magnetic random access memory data recording. The magnetic data recording element includes a magnetic tunnel junction element that includes a magnetic reference layer, a magnetic free layer and a non-magnetic barrier layer located between the non-magnetic reference layer and the magnetic free layer. The magnetic reference layer includes a layer of Hf that causes the magnetic reference layer to have an increased perpendicular magnetic anisotropy. This increased perpendicular magnetic anisotropy improves reliability and stability of the magnetic data recording element by preventing loss of magnetic orientation of the magnetic reference layer such as during high writing current conditions. ## Claims ### Claim 1 A magnetic random access memory element comprising: a magnetic reference layer; a magnetic free layer; and a non-magnetic barrier layer, located between the magnetic reference layer and the magnetic free layer; the magnetic reference layer comprising at least one magnetic layer and a layer of Hf; wherein the layer of Hf is located between the at least one magnetic layer and the non-magnetic barrier layer or the layer of Hf is located within the magnetic reference layer between a pair of magnetic layers. ### Claim 2 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf contacts the non-magnetic barrier layer. ### Claim 3 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf is part of a bi-layer structure that includes the layer of Hf and a layer of Mg—O. ### Claim 4 (depends on 3) The magnetic random access memory element as in claim 3, wherein the layer of Mg—O has a thickness that is no greater than 3 Angstroms. ### Claim 5 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf has a thickness that is not greater than 3 Angstroms. ### Claim 6 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf has a thickness of 1 Angstrom. ### Claim 7 (depends on 1) The magnetic random access memory element as in claim 1, wherein the magnetic reference layer further comprises a second layer of Hf. ### Claim 8 (depends on 1) The magnetic random access memory element as in claim 1, wherein the reference layer comprises a plurality of layers of Hf at different locations within the magnetic reference layer. ### Claim 9 (depends on 1) The magnetic random access memory element as in claim 1, wherein the reference layer further comprises, a separation layer located between magnetic layers. ### Claim 10 (depends on 9) The magnetic random access memory element as in claim 9, wherein the separation layer comprises Mo. ### Claim 11 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf is located between first and second layers of CoFeB. ### Claim 12 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf is located between a layer of CoFeB and a layer of MgO. ### Claim 13 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf has is located between first and second magnetic layers and wherein the layer of Hf has is sufficiently thin to avoid breaking exchange coupling between the first and second magnetic layers. ### Claim 14 (depends on 1) The magnetic random access memory element as in claim 1, wherein the layer of Hf is part of a bi-layer structure that includes the layer of Hf and a layer of Mo. ### Claim 15 (depends on 14) The magnetic random access memory element as in claim 14, wherein the layer of Hf and a layer of Mo is located between two magnetic layers of CofeB. ### Claim 16 A magnetic random access memory element comprising: a magnetic reference layer; a magnetic free layer; and a non-magnetic barrier layer, located between the magnetic reference layer and the magnetic free layer; the magnetic reference layer comprising: first and second magnetic layers; a separation layer located between the first and second layers; and a layer of Hf. ### Claim 17 (depends on 16) The magnetic random access memory element as in claim 16, wherein the layer of Hf is located between the second magnetic layer and the non-magnetic barrier layer. ### Claim 18 (depends on 16) The magnetic random access memory element as in claim 16 wherein the magnetic reference layer structure further comprises a third magnetic layer, and wherein the layer of Hf is located between the second and third magnetic layers. ### Claim 19 (depends on 17) The magnetic random access memory element as in claim 17, wherein the layer of Hf is part of a bi-layer structure that includes the layer of Hf and a layer of MgO. ### Claim 20 A magnetic random access memory system, comprising: a plurality of magnetic memory elements; and circuitry configured to write data to the plurality of magnetic memory elements and read data from the plurality of magnetic memory elements; each of the plurality of magnetic memory elements further comprising: a magnetic reference layer; a magnetic free layer; and a non-magnetic barrier layer, located between the magnetic reference layer and the magnetic free layer; and the magnetic reference layer comprising at least one magnetic layer and a layer of Hf; wherein the layer of Hf is located between the at least one magnetic layer and the non-magnetic barrier layer or the layer of Hf is located within the magnetic reference layer between a pair of magnetic layers.