# US 2020/0403149 A1 · Magnetic Element with Perpendicular Magnetic Anisotropy (PMA) and Improved Coercivity Field (Hc)/Switching Current Ratio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2020/0403149 A1 - Document ID: US20200403149A1 - Status: Published application - Kind: A1 - Application number: 16/448,348 - Filed: 2019-06-21 - Published: 2020-12-24 - Earliest claimed: 2019-06-21 - Assignees: Headway Technologies, Inc. - Applicants: Headway Technologies, Inc. - Inventors: Santiago Serrano Guisan; Luc Thomas; Jodi Mari Iwata; Guenole Jan; Ru-Ying Tong - Web page: https://patentgrep.com/patent/US20200403149A1 ## CPC - H10N 50/85: Materials of the active region - G11C 11/161: {details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell} - H10N 50/01: Manufacture or treatment - H10N 50/10: Magnetoresistive devices - H10N 52/01: Manufacture or treatment - H10N 52/80: Constructional details - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - G11C: STATIC STORES (semiconductor memory devices H10B) ## Abstract A perpendicular magnetic tunnel junction is disclosed wherein a metal insertion (MIS) layer is formed within a free layer (FL), a partially oxidized Hk enhancing layer is on the FL, and a nitride capping layer having a buffer layer/nitride layer (NL) is on the Hk enhancing layer to provide an improved coercivity (Hc)/switching current (Jc) ratio for spintronic applications. Magnetoresistive ratio is maintained above 100%, resistance×area (RA) product is below 5 ohm/μm2, and thermal stability to 400° C. is realized. The FL comprises two or more sub-layers, and the MIS layer may be formed within at least one sub-layer or between sub-layers. The buffer layer is used to prevent oxygen diffusion to the NL, and nitrogen diffusion from the NL to the FL. FL thickness is from 11 Angstroms to 25 Angstroms while MIS layer thickness is preferably from 0.5 Angstroms to 4 Angstroms. ## Claims ### Claim 1 A perpendicular magnetic tunnel junction (p-MTJ) structure, comprising: (a) a pinned layer (PL); (b) a tunnel barrier layer with a first surface that adjoins the PL, and a second surface that contacts a free layer (FL) and forms a first interface with the FL; (c) the FL that has a FL1/MIS/FL2 configuration wherein a metal insertion (MIS) layer is formed between a first FL sub-layer (FL1) and a second FL sub-layer (FL2), and wherein FL1 has perpendicular magnetic anisotropy (PMA) as a result of the first interface, and FL2 has PMA as a result of a second interface with a Hk enhancing layer; (d) the Hk enhancing layer having a non-stoichiometric oxidation condition, and that adjoins the FL to form the second interface on a side of the FL that is opposite to the first interface; and (e) a nitride capping layer (NCL), comprising: (1) a nitride layer (NL) that is a metal nitride or metal oxynitride; and (2) a buffer layer that adjoins the NL and contacts the Hk enhancing layer on a side thereof that is opposite to the second interface, wherein the buffer layer prevents oxygen diffusion from the Hk enhancing layer to the NL, and blocks nitrogen diffusion from the NL to the FL. ### Claim 2 (depends on 1) The p-MTJ of claim 1 wherein the MIS layer is a continuous layer, a multilayer, a discontinuous layer, or is a plurality of metal particles, or metal clusters. ### Claim 3 (depends on 1) The p-MTJ of claim 1 wherein the MIS layer has a thickness from 0.5 Angstroms to 4 Angstroms. ### Claim 4 (depends on 1) The p-MTJ of claim 1 wherein the MIS layer is a single layer or multilayer of one or more of Nb, Mo, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, Ir, Cu, Zn, Pt, Au, Ag, Pd, Al, B, Ga, Si, and Ge. ### Claim 5 (depends on 1) The p-MTJ of claim 1 wherein one or both of FL1 and FL2 is one or more of Co, Fe, CoFe, CoFeB, CoB, FeB, CoFeNi, and CoFeNiB. ### Claim 6 (depends on 1) The p-MTJ of claim 1 wherein one or both of FL1 and FL2 is comprised of a high Ku material having inherent PMA which is a Heusler alloy that is Ni2MnZ, Pd2MnZ, Co2MnZ, Fe2MnZ, Co2FeZ, Mn3Ge, or Mn2Ga where Z is one of Si, Ge, Al, Ga, In, Sn, and Sb, or an ordered L10 or L11 material with a composition that is one of MnAl, MnGa, or RT wherein R is Rh, Pd, Pt, Ir, or an alloy thereof, and T is Fe, Co, Ni, or an alloy thereof, or a rare-earth alloy with a TbFeCo, GdCoFe, FeNdB, or SmCo composition. ### Claim 7 (depends on 1) The p-MTJ of claim 1 where FL1 has a thickness t1, and FL2 has a thickness t2 where a sum of t1 and t2 is from 11 Angstroms to 25 Angstroms. ### Claim 8 (depends on 1) The p-MTJ of claim 1 wherein the Hk enhancing layer is a single layer or a laminate comprised of an oxide or oxynitride of one or more of Mg, Si, Sr, Ti, Ba, Ca, La, Al, Mn, V, and Hf, and has a resistance×area (RA) product less than a RA product of the tunnel barrier layer. ### Claim 9 (depends on 1) The p-MTJ of claim 1 further comprising a seed layer formed on a substrate, to yield a seed layer/PL/tunnel barrier layer/FL/Hk enhancing layer/NCL stack in a bottom spin valve configuration. ### Claim 10 (depends on 1) The p-MTJ of claim 1 further comprising a seed layer formed on a substrate, and a capping layer (CL) on the PL to yield a seed layer/NCL/Hk enhancing layer/FL/tunnel barrier layer/PL/CL stack in a top spin valve configuration. ### Claim 11 (depends on 1) The p-MTJ of claim 1 wherein the p-MTJ is incorporated in a magnetic random access memory (MRAM), spin transfer torque (STT)-MRAM, spin orbit torque (SOT)-MRAM, spin torque oscillator, Spin Hall Effect device, magnetic sensor, or a biosensor. ### Claim 12 (depends on 1) The p-MTJ of claim 1 wherein the NL is comprised of a metal nitride (M1N) or metal oxynitride (M1ON) where M1 is one or more of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, and Si. ### Claim 13 (depends on 1) The p-MTJ of claim 1 wherein the NL has a M2M3N or M2M3ON composition where M2 is one of B, Al, Si, Ga, In, and TI, and M3 is one or more of Pt, Au, Ag, Mg, Ca, Sr, Ba, Sc, Y, La, Co, Fe, Mn, Ru, Rh, Ir, Ni, Pd, Zn, Cu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W such that the NL is a conductive alloy layer, or has M3 conductive channels formed in a M2N or M2ON insulating matrix. ### Claim 14 (depends on 1) The p-MTJ of claim 1 wherein the buffer layer is a single layer or multilayer that is one or more of Mo, W, Ru, Nb, Ta, Cr, Pt, Cu, Au, Ag, Zn, V, Cd, Sn, Ir, Mn, Rh, Co, Fe, CoFe, CoB, FeB, CoFeNi, and CoFeNiB. ### Claim 15 A perpendicular magnetic tunnel junction (p-MTJ) structure, comprising: (a) a pinned layer (PL); (b) a tunnel barrier layer with a first surface that adjoins the PL, and a second surface that contacts a free layer (FL) and forms a first interface with the FL; (c) the FL that has a first metal insertion (MIS1) layer formed within one of a first FL sub-layer (FL1) and a second FL sub-layer (FL2), and wherein the FL has perpendicular magnetic anisotropy (PMA) as a result of the first interface, as a result of a second interface with a Hk enhancing layer; (d) the Hk enhancing layer having a non-stoichiometric oxidation condition, and that adjoins the FL to form the second interface on a side of the FL that is opposite to the first interface; and (e) a nitride capping layer (NCL), comprising: (1) a nitride layer (NL) that is a metal nitride or metal oxynitride; and (2) a buffer layer that adjoins the NL and contacts the Hk enhancing layer on a side thereof that is opposite to the second interface, wherein the buffer layer prevents oxygen diffusion from the Hk enhancing layer to the NL, and blocks nitrogen diffusion from the NL to the FL. ### Claim 16 (depends on 15) The p-MTJ of claim 15 wherein the MIS1 layer is formed within FL1 to give a FL1a/MIS1/FL1b/FL2 configuration wherein FL1a is a first sub-layer of FL1, and FL1b is a second sub-layer of FL1. ### Claim 17 (depends on 15) The p-MTJ of claim 15 wherein the MIS1 layer is formed within FL2 to give a FL1/FL2a/MIS1/FL2b configuration wherein FL2a is a first sub-layer of FL2, and FL2b is a second sub-layer of FL2. ### Claim 18 (depends on 16) The p-MTJ of claim 16 further comprised of a second MIS (MIS2) layer that is formed within FL2 to give a FL1a/MIS1/FL1b/FL2a/MIS2/FL2b configuration wherein FL2a is a first sub-layer of FL2, and FL2b is a second sub-layer of FL2. ### Claim 19 (depends on 18) The p-MTJ of claim 18 wherein the MIS1 layer has a composition that is different from a composition of the MIS2 layer. ### Claim 20 (depends on 15) The p-MTJ of claim 15 wherein the MIS1 layer is a single layer or multilayer of one or more of Nb, Mo, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, Ir, Cu, Zn, Pt, Au, Ag, Pd, Al, B, Ga, Si, and Ge. ### Claim 21 (depends on 15) The p-MTJ of claim 15 wherein one or both of FL1 and FL2 is one or more of Co, Fe, CoFe, CoFeB, CoB, FeB, CoFeNi, and CoFeNiB. ### Claim 22 (depends on 15) The p-MTJ of claim 15 wherein one or both of FL1 and FL2 is comprised of a high Ku material having inherent PMA which is a Heusler alloy that is Ni2MnZ, Pd2MnZ, Co2MnZ, Fe2MnZ, Co2FeZ, Mn3Ge, or Mn2Ga where Z is one of Si, Ge, Al, Ga, In, Sn, and Sb, or an ordered L10 or L11 material with a composition that is one of MnAl, MnGa, or RT wherein R is Rh, Pd, Pt, Ir, or an alloy thereof, and T is Fe, Co, Ni, or an alloy thereof, or a rare-earth alloy with a TbFeCo, GdCoFe, FeNdB, or SmCo composition. ### Claim 23 (depends on 15) The p-MTJ of claim 15 wherein FL1 has a thickness t1, and FL2 has a thickness t2 where a sum of t1 and t2 is from 11 Angstroms to 25 Angstroms. ### Claim 24 (depends on 15) The p-MTJ of claim 15 wherein the Hk enhancing layer is a single layer or a laminate comprised of an oxide or oxynitride of one or more of Mg, Si, Sr, Ti, Ba, Ca, La, Al, Mn, V, and Hf, and has a resistance×area (RA) product less than a RA product of the tunnel barrier layer. ### Claim 25 (depends on 15) The p-MTJ of claim 15 further comprising a seed layer formed on a substrate to yield a seed layer/PL/tunnel barrier layer/FL/Hk enhancing layer/NCL stack in a bottom spin valve configuration. ### Claim 26 (depends on 15) The p-MTJ of claim 15 further comprising a seed layer formed on a substrate, and a capping layer (CL) on the PL to yield a seed layer/NCL/Hk enhancing layer/FL/tunnel barrier layer/PL/CL stack in a top spin valve configuration. ### Claim 27 (depends on 15) The p-MTJ of claim 15 wherein the p-MTJ is incorporated in a magnetic random access memory (MRAM), spin transfer torque (STT)-MRAM, spin orbit torque (SOT)-MRAM, spin torque oscillator, Spin Hall Effect device, magnetic sensor, or a biosensor. ### Claim 28 (depends on 15) The p-MTJ of claim 15 wherein the NL is comprised of a metal nitride (M1N) or metal oxynitride (M1ON) where M1 is one or more of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, and Si. ### Claim 29 (depends on 15) The p-MTJ of claim 15 wherein the NL has a M2M3N or M2M3ON composition where M2 is one of B, Al, Si, Ga, In, and TI, and M3 is one or more of Pt, Au, Ag, Mg, Ca, Sr, Ba, Sc, Y, La, Co, Fe, Mn, Ru, Rh, Ir, Ni, Pd, Zn, Cu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W such that the NL is a conductive alloy layer, or has M3 conductive channels formed in a M2N or M2ON insulating matrix. ### Claim 30 (depends on 15) The p-MTJ of claim 15 wherein the buffer layer is a single layer or multilayer that is one or more of Mo, W, Ru, Nb, Ta, Cr, Pt, Cu, Au, Ag, Zn, V, Cd, Sn, Ir, Mn, Rh, Co, Fe, CoFe, CoB, FeB, CoFeNi, and CoFeNiB. ### Claim 31 (depends on 15) The p-MTJ of claim 15 wherein the MIS1 layer is a continuous layer, a multilayer, a discontinuous layer, or is a plurality of metal particles, or metal clusters. ### Claim 32 A method of forming a perpendicular magnetic tunnel junction (p-MTJ) having a first interface between a free layer (FL) and a first oxide layer that is a tunnel barrier layer, and a second interface between the FL and a Hk enhancing layer that is a second metal oxide layer or a metal oxynitride layer, comprising: (a) forming the FL on the tunnel barrier layer with a sputter deposition sequence, comprising; (1) depositing a first FL sub-layer on the tunnel barrier layer to form an interface that enhances perpendicular magnetic anisotropy in the FL; (2) depositing a first metal insertion (MIS1) layer on the first FL sub-layer; and (3) depositing a second FL sub-layer on the MIS1 layer; (b) forming a Hk enhancing layer that is a metal oxide layer on the FL; and (c) sequentially depositing a buffer layer and a nitride layer (NL) that is a metal nitride or metal oxynitride on the Hk enhancing layer wherein the buffer layer prevents oxygen diffusion from the Hk enhancing layer to the NL, and blocks nitrogen diffusion from the NL to the FL. ### Claim 33 (depends on 32) The method of claim 32 further comprised of depositing a third FL sub-layer on the second FL sub-layer to yield a FL1/MIS1/FL2/FL3 configuration where FL1, FL2, and FL3 are the first, second, and third FL sub-layers, respectively, such that the Hk enhancing layer is formed on FL3. ### Claim 34 (depends on 33) The method of claim 33 further comprised of forming a second MIS layer on FL3 and then a fourth FL sub-layer (FL4) on the MIS2 layer to yield a FL1/MIS1/FL2/FL3/MIS2/FL4 configuration. ### Claim 35 (depends on 32) The method of claim 32 wherein one or both of the first and second FL sub-layers is a single layer or multilayer of one or more of Co, Fe, CoFe, CoFeB, CoB, FeB, CoFeNi, and CoFeNiB. ### Claim 36 (depends on 32) The method of claim 32 wherein one or both of the first and second FL sub-layers is comprised of a high Ku material having inherent PMA which is a Heusler alloy that is Ni2MnZ, Pd2MnZ, Co2MnZ, Fe2MnZ, Co2FeZ, Mn3Ge, or Mn2Ga where Z is one of Si, Ge, Al, Ga, In, Sn, and Sb, or an ordered L10 or L11 material with a composition that is one of MnAl, MnGa, or RT wherein R is Rh, Pd, Pt, Ir, or an alloy thereof, and T is Fe, Co, Ni or an alloy thereof, or a rare-earth alloy with a TbFeCo, GdCoFe, FeNdB, or SmCo composition. ### Claim 37 (depends on 32) The method of claim 32 wherein the MIS1 layer a single layer or multilayer of one or more of Nb, Mo, Ta, W, Re, Ti, V, Cr, Zr, Hf, Ru, Rh, Os, Ir, Cu, Zn, Pt, Au, Ag, Pd, Al, B, Ga, Si, and Ge. ### Claim 38 (depends on 32) The method of claim 32 wherein the buffer layer is a single layer or multilayer that is one or more of Mo, W, Ru, Nb, Ta, Cr, Pt, Cu, Au, Ag, Zn, V, Cd, Sn, Ir, Mn, Rh, Co, Fe, CoFe, CoB, FeB, CoFeNi, and CoFeNiB. ### Claim 39 (depends on 32) The method of claim 32 wherein the NL is comprised of a metal nitride (M1N) or metal oxynitride (M1ON) where M1 is one or more of Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, and Si. ### Claim 40 (depends on 32) The method of claim 32 wherein the NL has a M2M3N or M2M3ON composition where M2 is one of B, Al, Si, Ga, In, and TI, and M3 is one or more of Pt, Au, Ag, Mg, Ca, Sr, Ba, Sc, Y, La, Co, Fe, Mn, Ru, Rh, Ir, Ni, Pd, Zn, Cu, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W such that the NL is a conductive alloy layer, or has M3 conductive channels formed in a M2N or M2ON insulating matrix. ### Claim 41 (depends on 32) The method of claim 32 wherein the MIS1 layer is a continuous layer, a multilayer, a discontinuous layer, or is a plurality of metal particles, or metal clusters.