# US 11,309,488 B2 · Double spin filter tunnel junction > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,309,488 B2 - Document ID: US11309488B2 - Status: Granted - Kind: B2 - Application number: 15/686,848 - Filed: 2017-08-25 - Published: 2017-12-07 - Granted: 2022-04-19 - Earliest claimed: 2015-10-06 - Assignees: International Business Machines Corporation - Applicants: International Business Machines Corporation - Inventors: Daniel C. Worledge - Web page: https://patentgrep.com/patent/US11309488B2 ## 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 50/80: Constructional details - H10B 61/00: Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices - H10N: ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR - G11C: STATIC STORES (semiconductor memory devices H10B) - H10B: ELECTRONIC MEMORY DEVICES ## Abstract A memory device that includes a first magnetic insulating tunnel barrier reference layer present on a first non-magnetic metal electrode, and a free magnetic metal layer present on the first magnetic insulating tunnel barrier reference layer. A second magnetic insulating tunnel barrier reference layer may be present on the free magnetic metal layer, and a second non-magnetic metal electrode may be present on the second magnetic insulating tunnel barrier. The first and second magnetic insulating tunnel barrier reference layers are arranged so that their magnetizations are aligned to be anti-parallel. ## Claims ### Claim 1 A memory device comprising: a substrate; a first magnetic insulating tunnel barrier reference layer having a magnetic insulating material on the substrate, the magnetic insulating material exhibiting an insulating property at room-temperature; a second magnetic insulating tunnel barrier reference layer on the first magnetic insulating tunnel barrier reference layer, the first and second magnetic insulating tunnel barrier reference layers each having a magnetization with a direction perpendicular to a major surface of the substrate and a magnetic polarization of at least 50% to reduce switching current; and a free magnetic metal layer, having a thickness between 5 Å and 10 Å, disposed directly between the first magnetic insulating tunnel barrier reference layer and the second magnetic insulating tunnel barrier reference layer, wherein a magnetic polarization of the free magnetic metal layer switches at current densities between 106 A/cm2 and 107 A/cm2. ### Claim 2 (depends on 1) The memory device of claim 1, further comprising a first metal electrode in direct contact with the first magnetic insulating tunnel barrier reference layer. ### Claim 3 (depends on 2) The memory device of claim 2, further comprising a second metallic electrode in direct contact with the second magnetic insulating tunnel barrier reference layer. ### Claim 4 (depends on 3) The memory device of claim 3, wherein at least one of the first metal electrode and the second metallic electrode is non-magnetic. ### Claim 5 (depends on 1) The memory device of claim 1, wherein the first magnetic insulating tunnel barrier reference layer comprises cobalt iron oxide (CoFeOx). ### Claim 6 (depends on 1) The memory device of claim 1, wherein the free magnetic metal layer comprises CoFeB. ### Claim 7 (depends on 1) The memory device of claim 1, wherein the free magnetic metal layer comprises alloys and/or multilayers including elements selected from the group consisting of Fe, Ni, Co, Cr, V, Mn, Pd, Pt, B, O, N and combinations thereof. ### Claim 8 (depends on 1) The memory device of claim 1, wherein the second magnetic insulating tunnel barrier reference layer comprises cobalt iron oxide (CoFeOx) or CoFeAOx, wherein A may be any element selected from the group consisting of beryllium (Be), boron (B), magnesium (Mg), aluminum (Al), silicon (Si), calcium (Ca), scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), zinc (Zn), yttria (Y), zirconia (Zr), niobium (Nb), molybdenum (Mo), technetium (Tc), ruthenium (Ru), rhenium (Rh), palladium (Pd), silver (Ag), cadmium (Cd), lutetium (Lu), hafnium (Hf), tantalum (Ta), tungsten (W), rhenium (Re), osmium (Os), iridium (Ir), platinum (Pt), gold (Au) mercury (Hg), and combinations thereof. ### Claim 9 (depends on 1) The memory device of claim 1, wherein the first magnetic insulating tunnel barrier reference layer, the free magnetic metal layer, and the second magnetic insulating tunnel barrier reference layer provide a magnetic tunnel junction (MJT). ### Claim 10 (depends on 1) The memory device of claim 1, wherein the first magnetic insulating tunnel barrier layer is in direct contact with a first side of the free magnetic metal layer and the second magnetic insulating tunnel barrier layer is in direct contact with a second side of the free magnetic metal layer. ### Claim 11 (depends on 1) The memory device of claim 1, wherein the first magnetic insulating tunnel barrier reference layer includes a magnetization in a first direction. ### Claim 12 (depends on 11) The memory device of claim 11, wherein the magnetization in the first direction ranges from 50 emu/cm3 to 600 emu/cm3. ### Claim 13 (depends on 11) The memory device of claim 11, wherein the second magnetic insulating tunnel barrier reference layer includes a magnetization in a second direction opposite the first direction. ### Claim 14 (depends on 1) The memory device of claim 1, wherein the first and second magnetic insulating tunnel barrier reference layers each have a thickness of 100 Å or less. ### Claim 15 A spin torque transfer magnetic random access memory device comprising: a magnetic tunnel junction stack between a pair of electrodes, wherein the magnetic tunnel junction stack comprises: a free magnetic metal layer having a thickness between 5 Å and 10 Å; a first magnetic insulating tunnel barrier reference layer, formed from magnetic insulating material that includes a spinel or garnet crystal structure, directly on a first face of the free magnetic metal layer and on a substrate, wherein the first magnetic insulating tunnel barrier reference layer has a magnetization with a direction perpendicular to a major surface of the substrate and a magnetic polarization of at least 50% to reduce switching current, the magnetic insulating material exhibiting an insulating property at room-temperature, wherein a magnetic polarization of the free magnetic metal layer switches at current densities between 106 A/cm2 and 107 A/cm2. ### Claim 16 (depends on 15) The spin torque transfer magnetic random access memory device of claim 15, wherein the first magnetic insulating tunnel barrier reference layer is in direct contact with the first face of the free magnetic metal layer, and a non-magnetic insulating tunnel barrier and a magnetic metallic reference layer is present on a second face of the free magnetic metal layer opposite the first face of the free magnetic metal layer, the non-magnetic insulating tunnel barrier being disposed between the free magnetic metal layer and the magnetic metallic reference layer. ### Claim 17 (depends on 15) The spin torque transfer magnetic random access memory device of claim 15, further comprising a second magnetic insulating tunnel barrier reference layer in direct contact with a second face of the free magnetic metal layer, wherein the first and second magnetic insulating tunnel barrier reference layers are arranged so that their magnetizations are aligned to be anti-parallel. ### Claim 18 (depends on 17) The spin torque transfer magnetic random access memory device of claim 17, wherein the free magnetic metal layer comprises alloys and/or multilayers including elements selected from the group consisting of Fe, Ni, Co, Cr, V, Mn, Pd, Pt, B, 0, N and combinations thereof. ### Claim 19 A memory device comprising: a first magnetic insulating tunnel barrier reference layer having a magnetic insulating material that comprises cobalt iron oxide (CoFeOx) with a thickness of 100 Å or less, the magnetic insulating material exhibiting an insulating property at room-temperature and having a magnetization in a first direction between 50 emu/cm3 and 600 emu/cm3; a first, non-magnetic metal electrode in direct contact with the first magnetic insulating tunnel barrier reference layer; a second magnetic insulating tunnel barrier reference layer on the first magnetic insulating tunnel barrier reference layer, with a thickness of 100 Å or less, having a magnetization in a second direction, opposite the first direction, the first and second magnetic insulating tunnel barrier reference layers each having a magnetic polarization of at least 90% to reduce switching current; a second, non-magnetic metal electrode in direct contact with the second magnetic insulating tunnel barrier reference layer; a free magnetic metal layer, comprising cobalt iron boron (CoFeB) having a thickness between 5 Å and 10 Å, disposed directly between the first magnetic insulating tunnel barrier reference layer and the second magnetic insulating tunnel barrier reference layer, wherein a magnetic polarization of the free magnetic metal layer switches at current densities between 106 A/cm2 and 107 A/cm2.