Voltage-controlled magnetoelectric memory and preparation method

Abstract

The present disclosure provides a voltage-controlled magnetoelectric memory and a preparation method. The memory comprises: a seed layer; a bottom electrode formed on the seed layer; a multiferroic layer formed on the bottom electrode; a topological spin-orbit coupling layer formed on the multiferroic layer; an interfacial modification layer formed on the topological spin-orbit coupling layer; a free-layer spin polarization enhancement layer formed on the interfacial modification layer; a first bridging layer formed on the free-layer spin polarization enhancement layer; a free layer formed on the first bridging layer and strongly ferromagnetically coupled to the free-layer spin polarization enhancement layer by means of the first bridging layer; a barrier layer formed on the free layer; a reference layer formed on the barrier layer; a second bridging layer formed on the reference layer; a reference-layer spin polarization enhancement layer formed on the second bridging layer and strongly ferromagnetically coupled to the reference layer by means of the second bridging layer; a coupling layer formed on the reference-layer spin polarization enhancement layer; a pinned layer formed on the coupling layer; and a capping layer formed on the pinned layer.

Description

Voltage-controlled magnetoelectric memory and its fabrication method Technical Field

[0001] This disclosure relates to the field of magnetic memory technology, and in particular to a voltage-controlled magnetoelectric memory and its fabrication method. Background Technology

[0002] Magnetic memory, as a novel type of memory, boasts advantages such as high speed, high stability, and high durability. However, existing magnetic memories still face numerous technical challenges. For instance, many improvements and refinements have been made regarding high-efficiency switching in SOT-MRAM. For example, patent CN110800057B discloses a high-spin Hall angle material, but lacks device structure optimization. Patent CN110993782B discloses a magnetic tunnel junction structure based on a high-spin Hall angle material, but lacks self-gating / assisted writing functionality, and its tunneling magnetoresistance effect is only moderately optimized. Patent CN112701216A discloses a voltage-controlled magnetic tunnel junction structure based on a high-spin Hall angle material, but still employs a conventional tunneling magnetoresistance structure. The tunneling magnetoresistance of existing magnetic tunnel junctions is only around 150%, and existing spin-orbit heavy metal materials typically have small spin Hall angles, resulting in high write current densities and a lack of self-gating functionality. Therefore, it is necessary to research a magnetic memory with a high-spin Hall angle and self-gating / assisted writing functionality, while simultaneously considering the read margin and the development requirements for high density and high energy efficiency in magnetic memory.

[0003] Public content

[0004] In view of the above, in order to at least partially solve at least one of the aforementioned technical problems, this disclosure provides a voltage-controlled magnetoelectric memory and a method for its fabrication.

[0005] According to one aspect of this disclosure, a voltage-controlled magnetoelectric memory (VMC) is provided, comprising: a seed layer; a bottom electrode formed on the seed layer; a multiferroic layer formed on the bottom electrode; a topological spin-orbit coupling layer formed on the multiferroic layer; an interface modification layer formed on the topological spin-orbit coupling layer; a free spin polarization enhancement layer formed on the interface modification layer; a first bridging layer formed on the free spin polarization enhancement layer; a free layer formed on the first bridging layer and strongly ferromagnetically coupled to the free spin polarization enhancement layer through the first bridging layer; a barrier layer formed on the free layer; a reference layer formed on the barrier layer; a second bridging layer formed on the reference layer; a reference spin polarization enhancement layer formed on the second bridging layer and strongly ferromagnetically coupled to the reference layer through the second bridging layer; a coupling layer formed on the reference spin polarization enhancement layer; a pinning layer formed on the coupling layer; and a capping layer formed on the pinning layer.

[0006] According to embodiments of this disclosure, the material of the topological spin-orbit coupling layer includes at least one of the following: SrIrO3, CaRuO3, SrRuO3, SrNbO3, and CaNbO3, with a thickness of 1-20 nm; the multiferroic layer material includes at least one of the following: BiFeO3, BiLaFeO3, TbMnO3, MbTiO3, CaMnO3, LuMnO3, and BaSrMnO3, with a thickness of 2-100 nm; the free spin polarization enhancement layer and the reference spin polarization enhancement layer are in a single-spin metallic state, and the materials include the following At least one of the following: CoFeSi, CoFeSiAl, NiCo2O4, NiMnSb, PtMnSb, NiCrSi, PdCrSi, CrO2, LaMnO3, SeMnO3, CrAs and their alloys, oxides and superlattices with different compositions or different doping; the free layer and the reference layer have perpendicular magnetic anisotropy, and the materials include at least one of the following: CoFeB, CoFe, multilayer Co / Pt, CoFeAl, multilayer Co / Pd and their composites, with a thickness of 0.5-10 nm.

[0007] According to embodiments of this disclosure, the barrier layer is made of at least one of the following: MgO, Al2O3, MgAlO and their constituent compounds; with a thickness of 0.5-3 nm; the pinning layer has strong perpendicular magnetic anisotropy and is made of at least one of the following: multilayer Co / Pt, CoFeB, CoFe, CoFeAl, multilayer Co / Pd and their composites, antiferromagnetic IrMn, FeMn, PtMn; with a thickness of 1-10 nm; the seed layer is made of at least one of the following: Pt, Ta, W, LaSrMnO, SrRuO3 and their composites, with a thickness of 1-3 nm.

[0008] According to embodiments of this disclosure, the bottom electrode is made of at least one of the following: LaSrMnO, SrRuO3, with a thickness of 2-10 nm; the spacer layer is made of at least one of the following: elemental metals Ru, W, Cu, Ta, Pt, Cr, Mo, Ir, V; the first bridging layer and the second bridging layer are made of at least one of the following: elemental metals W, Ru, Cu, Ta, Pt, Cr, Mo, Ir, V; the capping layer is made of at least one of the following: Ru, Ta, Ti, Cr, Pt, Au, CuN, TiN, and composite materials thereof.

[0009] According to an embodiment of this disclosure, a voltage is applied to the multiferroic layer, causing strain or charge injection at the interface where the multiferroic layer and the topological spin-orbit coupling layer meet. The strain or charge injection, when applied to the topological spin-orbit coupling layer, can regulate the rotation of the oxygen octahedron in the topological spin-orbit coupling layer and thus regulate the spin Hall angle.

[0010] According to embodiments of this disclosure, a free spin polarization enhancement layer and a reference spin polarization enhancement layer are configured to enhance the tunneling magnetoresistivity of a voltage-controlled magnetoelectric memory.

[0011] According to embodiments of this disclosure, the voltage-controlled magnetoelectric memory can achieve deterministic flipping without the assistance of an external magnetic field.

[0012] According to embodiments of this disclosure, the magnetization directions of the free layer, reference reference, pinned layer, free spin polarization enhancement layer, and reference spin polarization enhancement layer are either all in-plane or all out-of-plane.

[0013] In another aspect of this disclosure, a method for fabricating the above-described voltage-controlled magnetoelectric memory is provided, comprising operations S1-S6:

[0014] S1: Deposit a film stack on a wafer with designed interconnects and vias, including: seed layer, bottom electrode, multiferroic layer, and topological spin-orbit coupling layer;

[0015] S2: Further magnetron sputtering deposition of film stack, including: interface modification layer, free spin polarization enhancement layer, first bridging layer, free layer, barrier layer, reference layer, second bridging layer, reference spin polarization enhancement layer, coupling layer, pinning layer, and capping layer;

[0016] S3: The columnar structure in the middle region and the mesa on both sides are obtained by etching the topological spin-orbit coupling layer with ion beam and / or reactive ion beam.

[0017] S4: Insulating material is deposited by magnetron sputtering on the platform for isolation;

[0018] S5: Ion beam and / or reactive ion beam etching of via structures; and

[0019] S6: Magnetron sputtering and / or electron beam evaporation of metal electrodes and interconnect metals.

[0020] The voltage-controlled magnetoelectric memory proposed in this disclosure can achieve assisted, high-efficiency current writing; can achieve external field-free switching; and can obtain high tunneling magnetoresistivity. Attached Figure Description

[0021] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0022] Figure 1 is a schematic diagram of the voltage-controlled magnetoelectric memory structure according to an embodiment of this disclosure;

[0023] Figure 2 is a schematic diagram of the rotation of the oxygen octahedron in the voltage-controlled magnetoelectric memory of this embodiment;

[0024] Figures 3a-3f are process flow diagrams for fabrication of voltage-controlled magnetoelectric memory according to embodiments of the present disclosure. Detailed Implementation

[0025] This disclosure provides a voltage-controlled magnetoelectric memory and its fabrication method. The memory utilizes a multiferroic layer to control the rotation of oxygen octahedrons in the topological spin-orbit coupling layer, significantly regulating the spin Hall angle. Simultaneously, the tilting / rotation of the oxygen octahedrons at the interface induces z-polarized spin current generation, enabling assisted, efficient writing and deterministic flipping without external field. Furthermore, the spin polarization enhancement layer can improve the tunneling magnetoresistivity.

[0026] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0027] In this embodiment of the disclosure, a voltage-controlled magnetoelectric memory (VMC) is provided, as shown in FIG1. ​​The VMC comprises, from bottom to top, a seed layer; a bottom electrode formed on the seed layer; a multiferroic layer formed on the bottom electrode; a topological spin-orbit coupling layer formed on the multiferroic layer; an interface modification layer formed on the topological spin-orbit coupling layer; a free spin polarization enhancement layer formed on the interface modification layer; a first bridging layer formed on the free spin polarization enhancement layer; a free layer formed on the first bridging layer and strongly ferromagnetically coupled to the free spin polarization enhancement layer through the first bridging layer; a barrier layer formed on the free layer; a reference layer formed on the barrier layer; a second bridging layer formed on the reference layer; a reference spin polarization enhancement layer formed on the second bridging layer and strongly ferromagnetically coupled to the reference layer through the second bridging layer; a coupling layer formed on the reference spin polarization enhancement layer; a pinning layer formed on the coupling layer; and a capping layer formed on the pinning layer. Magnetic tunnel junction (MTJ) is a structure formed above a topological spin orbital layer.

[0028] The materials for the topological spin orbital layer include at least one of the following: SrIrO3, CaRuO3, SrRuO3, SrNbO3, CaNbO3, with a thickness of 1-20 nm; the materials for the multiferroic layer include at least one of the following: BiFeO3, BiLaFeO3, TbMnO3, MbTiO3, CaMnO3, LuMnO3, BaSrMnO3, with a thickness of 2-100 nm; the materials for the free / reference spin polarization enhancement layer include at least one of the following: single-spin metals CoFeSi, CoFeSiAl, NiCo2O4, NiMnSb, PtMnSb, NiCrSi, PdCrSi, CrO2, LaMnO3, S eMnO3, CrAs and their different composition / doped alloys and superlattices; the free layer and reference layer have perpendicular magnetic anisotropy, and their materials include at least one of the following: CoFeB, CoFe, multilayer Co / Pt, CoFeAl, multilayer Co / Pd and their composites; their thickness is 0.5-10 nm; the barrier layer is made of at least one of the following: MgO, Al2O3, MgAlO and their constituent compounds; its thickness is 0.5-3 nm; the pinning layer has strong perpendicular magnetic anisotropy, and its materials include at least one of the following: multilayer Co / Pt, CoFeB, CoFe, CoFeAl, multilayer Co / Pd and their composites, antiferromagnetic IrMn, FeMn, The material of the seed layer is PtMn with a thickness of 1-10 nm; the material of the seed layer includes at least one of the following: Pt, Ta, W, LaSrMnO, SrRuO3 and their composites, with a thickness of 1-3 nm; the material of the bottom electrode includes at least one of the following: LaSrMnO, SrRuO3, with a thickness of 2-10 nm; the material of the spacer layer includes at least one of the following: Ru, W, Cu, Ta, Pt, Cr, Mo, Ir, V metallic elements; the materials of the first bridging layer and the second bridging layer include at least one of the following: W, Ru, Cu, Ta, Pt, Cr, Mo, Ir, V metallic elements; the material of the capping layer includes at least one of the following: Ru, Ta, Ti, Cr, Pt, Au, CuN, TiN and their composites.

[0029] In this embodiment of the present disclosure, when a voltage is applied to the multiferroic layer, strain or charge injection is generated at the interface where the multiferroic layer and the topological spin-orbit coupling layer meet. After the strain or charge injection acts on the topological spin-orbit coupling layer, the oxygen octahedral rotation of the topological spin-orbit coupling layer can be controlled (as shown in Figure 2), thereby controlling the spin Hall angle.

[0030] The free spin polarization enhancement layer and the reference spin polarization enhancement layer are configured to enhance the tunneling magnetoresistivity of the voltage-controlled magnetoelectric memory. The magnetization directions of the free layer, the reference parameter, the pinned layer, the free spin polarization enhancement layer, and the reference spin polarization enhancement layer are either all in-plane or all out-of-plane.

[0031] In this embodiment of the disclosure, a method for fabricating the above-mentioned voltage-controlled magnetoelectric memory is also provided. Referring to Figures 3a-3f, the fabrication method includes:

[0032] S1: As shown in Figure 3a, a film stack is deposited on a wafer with designed interconnects and vias using magnetron sputtering and / or pulsed laser deposition equipment, including: a seed layer, a bottom electrode, a multiferroic layer, and a topological spin-orbit coupling layer.

[0033] S2: As shown in Figure 3b, the magnetron sputtering deposited film stack includes: an interface modification layer, a free spin polarization enhancement layer, a first bridging layer, a free layer, a barrier layer, a reference layer, a second bridging layer, a reference spin polarization enhancement layer, a coupling layer, a pinning layer, and a capping layer.

[0034] S3: As shown in Figure 3c, the columnar structure in the middle region and the mesa on both sides are obtained by etching the topological spin-orbit coupling layer with ion beam and / or reactive ion beam.

[0035] S4: As shown in Figure 3d, an insulating material is deposited by magnetron sputtering on the stage to obtain an isolation layer;

[0036] S5: As shown in Figure 3e, the through-hole structure on both sides of the device is etched by ion beam and / or reactive ion beam.

[0037] S6: As shown in Figure 3f, metal electrodes and interconnect metals are fabricated by magnetron sputtering and / or electron beam evaporation on the through-hole structure and the sealing layer to complete the fabrication of the voltage-controlled magnetoelectric memory.

[0038] The embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. It should be noted that implementations not illustrated or described in the drawings or the main text of the specification are forms known to those skilled in the art and are not described in detail. Furthermore, the definitions of the various elements and methods described above are not limited to the specific structures, shapes, or methods mentioned in the embodiments, and those skilled in the art can easily modify or substitute them. For example, the shape of the magnetoelectric storage device and the dimensions of its layers can be miniaturized according to the manufacturing process, and one or more MTJs can be integrated on the spin-orbit coupling layer.

[0039] Based on the above description, those skilled in the art should have a clear understanding of the magnetoelectric memory and its fabrication method disclosed herein.

[0040] In summary, this disclosure provides a voltage-controlled magnetoelectric memory and its fabrication method. The rotation of the oxygen octahedron in the topological spin-orbit coupling layer can be controlled through a multiferroic layer, significantly regulating the spin Hall angle. Simultaneously, the tilting / rotation of the oxygen octahedron at the interface can induce z-direction polarized spin current generation, enabling assisted, efficient writing and deterministic flipping without external field. Furthermore, the spin polarization enhancement layer can improve the tunneling magnetoresistivity.

[0041] The specific embodiments described above do not constitute a limitation on the scope of protection of this disclosure. Any other corresponding changes and modifications made based on the technical concept of this disclosure should be included within the scope of protection of the claims of this disclosure.

Claims

1. A voltage-controlled magnetoelectric memory, comprising: Seed layer; The bottom electrode is formed on top of the seed layer; A multi-iron layer is formed on the bottom electrode; A topological spin-orbit coupling layer is formed on top of a multiferroic layer; The interface modification layer is formed on topological spin-orbit coupling layer; A free spin polarization enhancement layer is formed on top of the interface modification layer; The first bridging layer is formed on top of the free spin polarization enhancement layer; The free layer is formed on the first bridging layer and is strongly ferromagnetically coupled to the free spin polarization enhancement layer through the first bridging layer; The barrier layer forms above the free layer; The reference layer is formed above the barrier layer; The second bridging layer is formed on top of the reference layer; A reference spin polarization enhancement layer is formed on the second bridging layer and is strongly ferromagnetically coupled to the reference layer through the second bridging layer; A coupling layer is formed on top of the reference spin polarization enhancement layer; The pinning layer is formed on top of the coupling layer; as well as The sealing layer is formed on top of the stapling layer.

2. The voltage-controlled magnetoelectric memory according to claim 1, wherein: The material of the topological spin-orbit coupling layer includes at least one of the following: SrIrO3, CaRuO3, SrRuO3, SrNbO3, and CaNbO3, with a thickness of 1-20 nm; The multi-iron layer material includes at least one of the following: BiFeO3, BiLaFeO3, TbMnO3, MbTiO3, CaMnO3, LuMnO3, BaSrMnO3, with a thickness of 2-100 nm; The free spin polarization enhancement layer and the reference spin polarization enhancement layer are in a single-spin metallic state, and the materials include at least one of the following: CoFeSi, CoFeSiAl, NiCo2O4, NiMnSb, PtMnSb, NiCrSi, PdCrSi, CrO2, LaMnO3, SeMnO3, CrAs and their alloys, oxides and superlattices with different compositions or different doping. The free layer and the reference layer have perpendicular magnetic anisotropy, and the materials include at least one of the following: CoFeB, CoFe, multilayer Co / Pt, CoFeAl, multilayer Co / Pd and their composite materials, with a thickness of 0.5-10 nm.

3. The voltage-controlled magnetoelectric memory according to claim 1, wherein: The barrier layer is made of at least one of the following: MgO, Al2O3, MgAlO and their constituent compounds; and has a thickness of 0.5-3 nm. The pinning layer has strong perpendicular magnetic anisotropy, and the material includes at least one of the following: multilayer Co / Pt, CoFeB, CoFe, CoFeAl, multilayer Co / Pd and their composite materials, antiferromagnetic IrMn, FeMn, PtMn; the thickness is 1-10nm; The seed layer is made of at least one of the following: Pt, Ta, W, LaSrMnO, SrRuO3 and their composites, with a thickness of 1-3 nm.

4. The voltage-controlled magnetoelectric memory according to claim 1, wherein: The material of the bottom electrode includes at least one of the following: LaSrMnO, SrRuO3, with a thickness of 2-10 nm; The material of the spacer layer includes at least one of the following: elemental metals Ru, W, Cu, Ta, Pt, Cr, Mo, Ir, and V; The materials of the first bridging layer and the second bridging layer include at least one of the following: elemental metals such as W, Ru, Cu, Ta, Pt, Cr, Mo, Ir, and V; The material of the sealing layer includes at least one of the following: Ru, Ta, Ti, Cr, Pt, Au, CuN, TiN, and composite materials thereof.

5. The voltage-controlled magnetoelectric memory according to claim 1, wherein a voltage is applied to the multiferroic layer, causing strain or charge injection at the interface where the multiferroic layer and the topological spin-orbit coupling layer meet, and the strain or charge injection acting on the topological spin-orbit coupling layer can regulate the oxygen octahedral rotation of the topological spin-orbit coupling layer and regulate the spin Hall angle.

6. The voltage-controlled magnetoelectric memory according to claim 1, wherein the free spin polarization enhancement layer and the reference spin polarization enhancement layer are configured to enhance the tunneling magnetoresistivity of the voltage-controlled magnetoelectric memory.

7. The voltage-controlled magnetoelectric memory according to claim 1 can achieve deterministic flipping without the assistance of an external magnetic field.

8. The voltage-controlled magnetoelectric memory according to claim 1, wherein the magnetization directions of the free layer, the reference parameter, the pinned layer, the free spin polarization enhancement layer, and the reference spin polarization enhancement layer are all in-plane or all out-of-plane.

9. A method for manufacturing a voltage-controlled magnetoelectric memory according to any one of claims 1-8, comprising: S1: Deposit a film stack on a wafer with designed interconnects and vias, including: seed layer, bottom electrode, multiferroic layer, and topological spin-orbit coupling layer; S2: Further magnetron sputtering deposition of film stack, including: interface modification layer, free spin polarization enhancement layer, first bridging layer, free layer, barrier layer, reference layer, second bridging layer, reference spin polarization enhancement layer, coupling layer, pinning layer, and capping layer; S3: The columnar structure in the middle region and the mesa on both sides are obtained by etching the topological spin-orbit coupling layer with ion beam and / or reactive ion beam. S4: Insulating material is deposited by magnetron sputtering on the table surface for isolation; S5: Ion beam and / or reactive ion beam etching of via structures; and S6: Magnetron sputtering and / or electron beam evaporation of metal electrodes and interconnect metals.

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