WO2022196741A1 - 磁気抵抗効果素子、磁気メモリ及び人工知能システム - Google Patents
磁気抵抗効果素子、磁気メモリ及び人工知能システム Download PDFInfo
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- G—PHYSICS
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- G06N—COMPUTING ARRANGEMENTS BASED ON SPECIFIC COMPUTATIONAL MODELS
- G06N3/00—Computing arrangements based on biological models
- G06N3/02—Neural networks
- G06N3/06—Physical realisation, i.e. hardware implementation of neural networks, neurons or parts of neurons
- G06N3/063—Physical realisation, i.e. hardware implementation of neural networks, neurons or parts of neurons using electronic means
- G06N3/065—Analogue means
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- H—ELECTRICITY
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- H01F10/00—Thin magnetic films, e.g. of one-domain structure
- H01F10/26—Thin magnetic films, e.g. of one-domain structure characterised by the substrate or intermediate layers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F10/00—Thin magnetic films, e.g. of one-domain structure
- H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
- H01F10/00—Thin magnetic films, e.g. of one-domain structure
- H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
- H01F10/3213—Exchange coupling of magnetic semiconductor multilayers, e.g. MnSe/ZnSe superlattices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L29/00—Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor
- H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
- H01L29/82—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by variation of the magnetic field applied to the device
-
- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10B—ELECTRONIC MEMORY DEVICES
- H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/10—Magnetoresistive devices
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
- H10N50/00—Galvanomagnetic devices
- H10N50/80—Constructional details
- H10N50/85—Magnetic active materials
Definitions
- the present invention relates to magnetoresistive elements, magnetic memories, and artificial intelligence systems.
- spin injection magnetization switching which consists of a recording layer comprising a first ferromagnetic layer having magnetization that can be switched, and a recording layer that is an insulator.
- MTJ magnetic tunnel junction
- the first Invert the magnetization of the ferromagnetic layer.
- SOT spin orbit torque
- MRAM Magnetic Random Access Memory
- the SOT-MRAM element is configured by providing an MTJ including a recording layer/barrier layer/reference layer on a heavy metal layer. Spins polarized by the flow flow into the recording layer, and the magnetization of the recording layer is reversed, whereby the direction of magnetization in the recording layer switches between parallel and antiparallel states with the direction of magnetization in the reference layer. Data is recorded (Patent Documents 1 to 3).
- the write efficiency is expected to be improved due to the high specific resistance, but the power consumption is large.
- the present invention provides a magnetoresistive effect element, a magnetic memory, and an artificial intelligence capable of efficiently reversing the direction of magnetization in the recording layer with low resistance and without lowering the reversing efficiency by a write current flowing through the heavy metal layer.
- the purpose is to provide a system.
- a heavy metal layer formed by stacking an Ir layer and a Pt layer; a recording layer provided to face the heavy metal layer and comprising a first ferromagnetic layer having reversible magnetization; a reference layer comprising a second ferromagnetic layer with a fixed direction of magnetization; a barrier layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer and made of an insulator; with A magnetoresistive element in which the direction of magnetization in the first ferromagnetic layer is reversed by a write current flowing through the heavy metal layer.
- a heavy metal layer formed by laminating an Ir layer and a Pt layer, a recording layer provided so as to face the heavy metal layer and including a first ferromagnetic layer having reversible magnetization, a reference layer comprising a second ferromagnetic layer whose direction is fixed; and a barrier layer sandwiched between the first ferromagnetic layer and the second ferromagnetic layer and made of an insulating material Therefore, the direction of magnetization in the first ferromagnetic layer can be efficiently reversed with low resistance by the write current flowing through the heavy metal layer without lowering the reversing efficiency.
- FIG. 1 is a perspective view schematically showing a magnetoresistive effect element according to a first embodiment of the invention.
- FIG. 2 is a cross-sectional view of the magnetoresistive element shown in FIG.
- FIG. 3 is a diagram for explaining a method of writing data "0" to a magnetoresistive element storing data "1", and shows an initial state of magnetization.
- FIG. 4 is a diagram for explaining a method of writing data "0" to a magnetoresistive element storing data "1", and shows a state in which data is written by applying a write current.
- FIG. 5 relates to a diagram for explaining a method of writing data "1” to a magnetoresistive element storing data "0", and shows an initial state of magnetization.
- FIG. 1 is a perspective view schematically showing a magnetoresistive effect element according to a first embodiment of the invention.
- FIG. 2 is a cross-sectional view of the magnetoresistive element shown in FIG.
- FIG. 3 is
- FIG. 6 relates to a diagram for explaining a method of writing data "1" to a magnetoresistive element storing data "0", and shows a state in which data is written by applying a write current.
- FIG. 7 is a diagram for explaining a method of reading data stored in the magnetoresistive effect element.
- FIG. 8 is a timing chart of signals for writing data to the magnetoresistive effect element.
- FIG. 9 is a cross-sectional view of a magnetoresistive element according to a second embodiment of the invention.
- FIG. 10 is a diagram showing how data is rewritten in the magnetoresistive element shown in FIG.
- FIG. 11 is a cross-sectional view of a magnetoresistive element according to a third embodiment of the invention.
- FIG. 12A and 12B are diagrams showing how data is rewritten in the magnetoresistive element shown in FIG. 11.
- FIG. FIG. 13 is a perspective view schematically showing a magnetoresistive effect element according to the fourth embodiment.
- 14 is a plan view of the third terminal shown in FIG. 13.
- FIG. 15 is a perspective view schematically showing a magnetic memory according to the fifth embodiment of the invention.
- FIG. 16 is a diagram showing an outline of an AI system according to the sixth embodiment of the present invention.
- FIG. 17 is a circuit diagram of an example of an AI system using magnetoresistive elements.
- FIG. 18 is a diagram showing an outline of an AI system different from that in FIG.
- FIG. 19 is a plan view of an AI system according to the sixth embodiment of the invention.
- FIG. 20 is a plan view of an AI system according to a sixth embodiment of the present invention different from FIG. 19.
- FIG. FIG. 21A is a cross-sectional view of the manufactured first sample.
- FIG. 21B is a cross-sectional view of the manufactured second sample.
- FIG. 21C is a cross-sectional view of the manufactured third sample.
- FIG. 21D is a cross-sectional view of the manufactured fourth sample.
- FIG. 21E is a cross-sectional view of the manufactured fifth sample.
- FIG. 21F is a cross-sectional view of the manufactured sixth sample.
- FIG. 21G is a cross-sectional view of the manufactured seventh sample.
- FIG. 21H is a cross-sectional view of the manufactured eighth sample.
- FIG. 21I is a cross-sectional view of a manufactured comparative sample.
- FIG. 21J is a cross-sectional view of the fabricated ninth sample.
- FIG. 22 is a diagram showing heavy metal layer thickness dependence of electrical conductivity of the third sample.
- FIG. 23 is a diagram showing heavy metal layer thickness dependence of electrical conductivity of the fourth sample.
- FIG. 24 is a diagram showing heavy metal layer thickness dependence of electrical conductivity of the fifth sample.
- FIG. 25 shows the results of the specific resistance obtained from the thickness dependence of the electrical conductivity of the heavy metal layer in each sample.
- FIG. 26 is a diagram showing the spin generation efficiency ⁇ SH for each sample.
- FIG. 27 is a diagram showing the spin conductivity ⁇ SH in each sample.
- FIG. 28 shows the spin generation efficiency ⁇ SH with respect to each thickness ratio of the Pt layer and the Ir layer in each sample.
- FIG. 29 shows the specific resistance ⁇ XX with respect to each film thickness ratio of the Pt layer and the Ir layer in each sample.
- FIG. 30 shows the spin conductivity ⁇ SH with respect to each film thickness ratio of the Pt layer and the Ir layer in each sample.
- FIG. 31 is a diagram showing the heavy metal layer thickness dependence of the electrical conductivity of the ninth sample.
- FIG. 32 is a diagram showing heavy metal layer thickness dependence of electrical conductivity.
- FIG. 33 shows the result of examining the interlayer magnetic coupling between the Ir/Pt spacers of the tenth sample.
- FIG. 34 is a diagram schematically showing a Hall bar and a measurement system fabricated as the 11th sample.
- FIG. 35A is a cross-sectional view of the fabricated 11th sample.
- FIG. 35B is a cross-sectional view of another manufactured comparative sample.
- FIG. 36 is a diagram showing the pulse current dependence of the Hall resistance of the 11th sample and another comparative sample.
- FIG. 1 is a perspective view schematically showing a magnetoresistive element 10 according to a first embodiment of the invention
- FIG. 2 is a cross-sectional view of the magnetoresistive element 10 shown in FIG.
- the magnetoresistive element 10 according to the first embodiment of the present invention includes a heavy metal layer 11, a recording layer 16, a barrier layer 17, and a reference layer 18.
- the recording layer 16 sandwiches the barrier layer 17 between the reference layers. 18 , that is, on the heavy metal layer 11 side, and the reference layer 18 is arranged on the opposite side of the heavy metal layer 11 with the barrier layer 17 interposed therebetween.
- the recording layer 16, the barrier layer 17, and the reference layer 18 form a magnetic tunnel junction (MTJ).
- MTJ magnetic tunnel junction
- the magnetoresistive element 10 uses a spin orbit torque (SOT) induced magnetization reversal by a current (referred to as a “write current”) flowing through the heavy metal layer 11 to cause the first magnetic field in the recording layer 16 to change.
- SOT spin orbit torque
- MRAM Magnetic Random Access Memory
- the heavy metal layer 11 is configured by stacking an Ir layer 12 and a Pt layer 13 .
- the heavy metal layer 11 is formed on the substrate 1 with the buffer layer 2 provided as necessary.
- the heavy metal layer 11 is configured by laminating the Ir layer 12 and the Pt layer 13, the outermost Pt layer 13 among the plurality of Pt layers 13, that is, the Pt layer 13 closest to the recording layer 16 in the lamination direction is It is preferable to form an interface with the recording layer 16 . This is because providing the Pt layer 13 on the recording layer 16 side of the heavy metal layer 11 is preferable to providing the Ir layer in terms of the spin Hall angle ⁇ SH , electrical resistivity ⁇ , and electrical conductivity ⁇ SH .
- the heavy metal layer 11 may be a case where the Ir layer 12 and the Pt layer 13 are laminated one by one. Even in this case, it is preferable that the Ir layer 12 is provided on the substrate 1 side and the Pt layer 13 is provided on the recording layer 16 side opposite to the substrate 1 side. Alternatively, as shown in FIGS. 1 and 2, the Ir layer 12 and the Pt layer 13 may be repeatedly laminated. When the Ir layer 12 and the Pt layer 13 are laminated repeatedly, the substrate 1 side and the buffer layer 2 side may be either the Pt layer 13 or the Ir layer 12 . That is, of the Ir layer 12 and the Pt layer 13 forming a part of the heavy metal layer 11, the Pt layer 13 may be the one layer closer to the recording layer 16.
- each Pt layer 13 preferably has a thickness of more than 0.6 nm and less than or equal to 1.5 nm.
- the Ir layer 12 preferably has a thickness of 0.6 nm or more and 1.5 nm or less per layer.
- the Ir layer 12 is a layer made of Ir (iridium)
- the Pt layer 13 is a layer made of Pt (platinum). At least one or two layers of the Ir layer 12 and the Pt layer 13 are provided, and the number of layers is adjusted so that the total thickness of the heavy metal layer 11 is about 10 nm or less. is.
- the recording layer 16 includes a first ferromagnetic layer having reversible magnetization, and is provided so as to face, for example, contact with the Pt layer 13 which is the outermost layer of the heavy metal layer 11 .
- the recording layer 16 has a thickness of 0.8 nm or more and 5.0 nm or less, preferably 1.0 nm or more and 3.0 nm or less.
- the recording layer 16 may be magnetized perpendicularly to the first ferromagnetic layer. Therefore, the recording layer 16 is configured to be capable of magnetization reversal in the direction perpendicular to the film surface. Note that the term "perpendicularly magnetized" includes the possibility of having a magnetization component parallel to the film surface.
- the recording layer 16 may be magnetized in the in-plane direction with respect to the first ferromagnetic film. Therefore, the recording layer 16 is configured to be capable of magnetization reversal in the in-plane direction with respect to the film surface. Note that "magnetized in the in-plane direction" means that the film may have a magnetization component perpendicular to the film plane.
- the recording layer 16, that is, the first ferromagnetic layer is composed of CoFeB, FeB, CoB, or the like in order to generate interfacial magnetic anisotropy in the recording layer 16.
- FIG. When shape magnetic anisotropy is used in a fine MTJ region, CoFeB, FeB, and CoB may be processed to have the longest length in the film thickness direction, and these single layers may be used as the recording layer.
- the barrier layer 17 is formed facing the first ferromagnetic layer of the recording layer 16 .
- the barrier layer 17 is preferably made of an insulating material such as MgO, Al2O3 , AlN, MgAlO, especially MgO.
- the barrier layer 17 has a thickness of 0.1 nm or more and 2.5 nm or less, preferably 0.5 nm or more and 1.5 nm or less.
- the reference layer 18 may be composed of a single layer as shown in FIG. 1 and FIG. may have.
- the magnetization direction of one ferromagnetic layer and the magnetization direction of the other ferromagnetic layer are antiparallel.
- the magnetization of one ferromagnetic layer is oriented in the -z direction and the magnetization of the other ferromagnetic layer is oriented in the +z direction.
- the magnetization of one ferromagnetic layer is oriented, for example, in the -x direction, and the magnetization of the other ferromagnetic layer is oriented in the +x direction.
- the magnetization directions of one ferromagnetic layer and the other ferromagnetic layer may be in the xy plane.
- the second ferromagnetic layer of the reference layer 18 closest to the barrier layer 17 is formed so that interfacial magnetic anisotropy occurs at the interface between the second ferromagnetic layer of the reference layer 18 closest to the barrier layer 17 and the barrier layer 17 .
- material and thickness are selected.
- the reference layer 18 has a laminated ferrimagnetic structure, and the magnetization of one ferromagnetic layer of the reference layer 18 and the magnetization of the other ferromagnetic layer are antiferromagnetically coupled, so that one of the reference layers 18 The magnetization of one ferromagnetic layer and the magnetization of the other ferromagnetic layer are fixed in the perpendicular or in-plane direction.
- Magnetization of one ferromagnetic layer and magnetization of the other ferromagnetic layer of the reference layer 18 may be antiferromagnetically coupled by interlayer interaction to fix the magnetization direction.
- the second ferromagnetic layer and the like in the reference layer 18 are made of the same material as the ferromagnetic material and the like that make up the recording layer 16 .
- the recording layer 16, the barrier layer 17, and the reference layer 18 have a columnar shape, and the recording layer 16, the barrier layer 17, and the reference layer 18 are stacked in the stacking direction of the heavy metal layer 11.
- the shape seen from above, that is, the shape in plan view has a line symmetrical shape with respect to a line passing through the center of the circle. It is line symmetrical with respect to
- the cap layer 19 is a layer of about 1.0 nm made of a conductive material such as Ta to prevent oxidation, and may be formed adjacent to the reference layer 18 . Also, the cap layer 19 may be formed of a non-magnetic layer such as MgO, a tunnel current flows through the cap layer 19, and a current flows through the reference layer 18 from the third terminal T3.
- the first terminal T1 and the second terminal T2 sandwich the MTJ consisting of the recording layer 16/barrier layer 17/reference layer 18, either above or below the heavy metal layer 11, or with one facing downward and the other facing upward, is provided.
- the first terminal T1 is provided on the heavy metal layer 11
- the second terminal T2 is provided on the heavy metal layer 11 with the MTJ composed of the recording layer 16/barrier layer 17/reference layer 18 interposed therebetween. It is provided on the side opposite to the first terminal T1.
- the first terminal T1 is connected to either the source or the drain of the FET-type first transistor Tr1, and the other of the source and the drain of the first transistor Tr1 is connected to the first bit line, It is connected to a power supply (write power supply) that supplies a write voltage Vw , and the gate of the FET-type first transistor Tr1 is connected to the word line.
- the second terminal T2 is connected to ground, for example. At that time, the FET type second transistor Tr2 may be interposed.
- the second terminal T2 is connected to the second bit line through the second transistor Tr2, and the direction of the write current Iw is changed according to the potential difference between the first terminal T1 and the second terminal T2.
- the first bit line is set to High level
- the second bit line is set to Low level
- the write current Iw is passed from the first terminal T1 to the second terminal T2.
- the first bit line is set to Low level
- the second bit line is set to High level
- the write current Iw is passed from the second terminal T2 to the first terminal T1.
- the second transistor Tr2 is turned off so that the read current does not flow to the second terminal T2.
- the third terminal T3 is provided on the cap layer 19 in contact with the cap layer 19 .
- the third terminal T3 has the same cylindrical shape as the recording layer 16, the barrier layer 17 and the reference layer 18, the third terminal T3 is arranged on the upper surface of the cap layer 19 and covers the entire surface of the upper surface, It is electrically connected to the reference layer 18 via the cap layer 19 .
- the third terminal T3 is connected to either the source or the drain of the FET-type third transistor Tr3, and the other of the source and the drain of the third transistor Tr3 is connected to the third bit line, It is connected to a power source (read power source) that supplies a read voltage V Read , and the gate of the third transistor Tr3 is connected to the read voltage line. By turning off the second transistor Tr2, it is possible to prevent current from flowing through the second terminal T2.
- FIG. 1 A method of writing to the magnetoresistive element 10 shown in FIG. 1 will be described.
- the magnetization directions of the first ferromagnetic layer and the second ferromagnetic layer adjacent to each other with the barrier layer 17 interposed between the recording layer 16 and the reference layer 18 are parallel or anti-parallel.
- the resistance of the MTJ changes depending on whether it is parallel. Therefore, 1-bit data of "0" and "1" are assigned depending on whether the magnetization directions are parallel or antiparallel, and the data is stored in the magnetoresistive element 10.
- the magnetoresistive element 10 stores data "1"
- the direction of the magnetization M11 of the recording layer 16 is upward
- the direction of the magnetization M12 of the reference layer 18 is downward.
- the directions of magnetization M11 and magnetization M12 are assumed to be antiparallel.
- the first transistor Tr1 and the third transistor Tr3 are turned off.
- An external magnetic field H 0 is applied in the +x direction.
- the first transistor Tr1 is turned on and the write voltage Vw is applied to the first terminal T1.
- the write current Iw flows from the first terminal T1 through the heavy metal layer 11 to the second terminal T2, and one end of the heavy metal layer 11 A write current Iw flows in the +x direction from the terminal to the other end.
- the third transistor Tr3 since the third transistor Tr3 is off, no current flows from the first terminal T1 to the third terminal T3 via the MTJ. Since the write current Iw is a pulse current, the pulse width of the write current Iw is changed by adjusting the ON state time of the first transistor Tr1.
- a spin current flow of spin angular motion
- the spins in the opposite directions flow into the heavy metal layer 11, respectively.
- the spins are unevenly distributed in the heavy metal layer 11 by flowing in corresponding directions of the ⁇ z directions.
- Spins directed in one direction are absorbed in the recording layer 16 by the spin current flowing through the heavy metal layer 11 .
- the absorbed spin causes a torque to act on the magnetization M11, and the torque rotates the magnetization M11 to reverse the upward magnetization M11 to become downward, and the directions of the magnetization M11 and the magnetization M12 are changed. becomes parallel.
- FIG. 4 shows this state.
- the magnetoresistive element 10 stores data "0"
- the direction of the magnetization M11 of the recording layer 16 is downward
- the direction of the magnetization M12 of the reference layer 18 is downward.
- the directions of magnetization M11 and magnetization M12 are assumed to be parallel.
- the first transistor Tr1 and the third transistor Tr3 are turned off.
- An external magnetic field H 0 is applied in the +x direction.
- the first transistor Tr1 is turned on and the write voltage Vw is applied to the first terminal T1.
- the write current Iw flows from the second terminal T2 to the first terminal T1 through the heavy metal layer 11, A write current Iw flows in the -x direction from one end to the other.
- the third transistor Tr3 since the third transistor Tr3 is off, no current flows from the second terminal T2 to the third terminal T3 via the MTJ. Since the write current Iw is a pulse current, the pulse width of the write current Iw can be changed by adjusting the ON state time of the first transistor Tr1.
- the magnetization direction of the recording layer 16 is reversed by passing the write current Iw between one end and the other end of the heavy metal layer 11, thereby generating data "0" or data "1". ” can be written.
- the magnetoresistive element 10 applies a voltage between one end (first terminal T1) and the other end (second terminal T2) of the heavy metal layer 11 to apply a write current to the heavy metal layer 11.
- the magnetization M11 of the recording layer 16 is caused by spins injected from the heavy metal layer 11. may be reversed in magnetization.
- the write voltage Vw is set to a voltage higher than the read voltage VRead .
- the first transistor Tr1 and the third transistor Tr3 are turned on, the write voltage Vw is applied to the first terminal T1, and the read voltage VRead is applied to the third terminal T3. Since the write voltage Vw is set higher than the read voltage VRead , from the first terminal T1 to the heavy metal layer 11, the recording layer 16, the barrier layer 17, the reference layer 18, the cap layer 19, and the third terminal T3.
- a read current Ir flows in order.
- a read current Ir flows through the barrier layer 17 .
- a read current Ir is detected by a detector (not shown).
- the magnitude of the read current Ir determines whether the MTJ is in a parallel state or antiparallel state, that is, whether the MTJ stores data “0” or not. It is possible to read whether "1" is stored.
- the read current Ir is a pulse current, and the pulse width is adjusted by adjusting the time during which the third transistor Tr3 is turned on.
- the read current Ir is desirably set to such a weak current that the recording layer 16 does not undergo spin-injection magnetization reversal due to the read current Ir when the read current Ir flows through the MTJ.
- the magnitude of the read current Ir is adjusted by appropriately adjusting the potential difference between the write voltage Vw and the read voltage VRead .
- the first transistor Tr1 is turned off.
- the magnetoresistive element 10 can protect the barrier layer 17, make the barrier layer 17 thinner, and further suppress the read disturbance in which the magnetization state of the recording layer 16 changes due to the current flowing through the MTJ. can be done.
- FIG. is provided as an MTJ.
- the first transistor Tr1 connected to the first terminal T1 of the heavy metal layer 11 and the third transistor Tr3 connected to the third terminal T3 of each MTJ are all turned off. If necessary, the magnetic anisotropy of the recording layer 16 is reduced by turning on the third transistor Tr3 connected to the third terminal T3.
- the write voltage Vw is set to a positive voltage to turn on the first transistor Tr1 connected to the first terminal T1, causing the write current Iw to flow from the first terminal T1 to the second terminal T2.
- the recording layer 16 having perpendicular magnetization rotates and the axis of easy magnetization is not determined in a stable direction.
- all of the third transistors Tr3 connected to the third terminal T3 in each MTJ are turned on to allow the write auxiliary current IWA to flow, and only the portions to which it flows are written.
- all the third transistors Tr3 connected to the third terminal T3 in each MTJ are turned off, and the first transistors Tr1 connected to the first terminal T1 are turned off.
- the write voltage Vw is set to a negative voltage to turn on the first transistor Tr1 connected to the first terminal T1, and the write current Iw flows from the second terminal T2 to the first terminal T1.
- the magnetic anisotropy constant ⁇ of the recording layer 16 is reduced to 5 to 15, the recording layer 16 having perpendicular magnetization rotates when the write current Iw is applied, and the axis of easy magnetization is not determined in a stable direction.
- the layer 16 is defined in the direction of the write assist current IWA and the spin transfer torque flips the easy axis to the steady state.
- this element is used as a cross-point memory of a crossbar network, if the magnetic anisotropy constant ⁇ of the recording layer 16 is reduced to 5 to 15, the recording layer 16 having perpendicular magnetization will rotate when the write current Iw is applied. However, the axis of easy magnetization is not determined in a stable direction, but this is written by wiring for applying a magnetic field, which will be described later. At this time, since the magnetic anisotropy constant ⁇ of the recording layer 16 is as small as 5 to 15, writing can be performed with a small current magnetic field.
- FIG. 8 is a timing chart of signals for writing data to the magnetoresistive effect element.
- the write current Iw and the write auxiliary current IWA are pulsed currents. As shown in FIG. 8, the pulse of the write current Iw and the pulse of the write auxiliary current IWA are timings at least partially overlapping each other. For example, as shown in FIG. 8, the write current Iw is pulsed on first and the write auxiliary current IWA is pulsed on before the write current Iw is pulsed off. After this, the write current Iw is pulsed off and the write auxiliary current IWA is pulsed off.
- data "1” may be written to all MTJs collectively, and then data "0" may be written only to selected MTJs.
- the third transistor Tr3 connected to the third terminal T3 of the MTJ to be read is turned on. This is done by applying a read current Ir to the MTJ.
- the reading method is the same as in the first embodiment.
- the magnetoresistive element 10 includes a heavy metal layer 11 formed by laminating an Ir layer 12 and a Pt layer 13, and the heavy metal layer 11 facing the heavy metal layer 11.
- a reference comprising a recording layer 16 including a first ferromagnetic layer having reversible magnetization and a second ferromagnetic layer having a fixed magnetization direction provided on the upper Pt layer 13 side
- the layer 18 and the barrier layer 17 sandwiched between the first ferromagnetic layer and the second ferromagnetic layer and made of an insulator are provided.
- the direction of magnetization in the first ferromagnetic layer of the recording layer 16 can be efficiently reversed by the resistance without lowering the reversal efficiency.
- external magnetic fields are not used by adjusting the shapes of the recording layer 16, the barrier layer 17, and the reference layer 18 in a plan view, or by adjusting the directions of the spins in the recording layer 16 and the reference layer 18, respectively.
- the magnetization directions of the recording layer 16 and the reference layer 18 can be either in-plane parallel or in-plane perpendicular.
- FIG. 9 is a cross-sectional view of a magnetoresistive element 30 according to a second embodiment of the invention.
- the heavy metal layer 11 is formed by laminating an Ir layer 12 and a Pt layer 13 one by one.
- a magnetic layer 15 is provided correspondingly.
- the magnetization M21 of one ferromagnetic layer 14 and the magnetization M22 of the other ferromagnetic layer 15 are both in opposite directions. That is, when the buffer layer 2 is provided on the substrate 1 as necessary and the heavy metal layer 11 is provided thereon, one ferromagnetic layer 14 is provided on the substrate 1 or buffer layer 2 side of the heavy metal layer 11 .
- the other ferromagnetic layer 15 is provided on the recording layer 16 side.
- the reason why the Ir layer 12 and the Pt layer 13 are one layer each is that the ferromagnetic layer 14 on one side and the ferromagnetic layer 15 on the other side are antiferromagnetically coupled.
- the recording layer 16 and the reference layer 18 are also preferably perpendicular magnetization layers. .
- the spin Hall effect causes one of the ferromagnetic layers 14 to
- the magnetizations of the magnetic layer 14 and the ferromagnetic layer 15 are reversed, and under the influence of the magnetization reversal of the ferromagnetic layer 14 and the ferromagnetic layer 15, the magnetization of the recording layer 16 is reversed.
- a write current Iw in the +x direction as shown on the left side of FIG.
- the direction of magnetization M11 is reversed.
- the Pt layer 13 preferably has a thickness of 0.6 nm or more and 1.0 nm or less.
- the Ir layer 12 is preferably 0.45 nm or more and 0.65 nm or less, and 1.3 nm or more and 1.5 nm or less. This is because one ferromagnetic layer 14 and the other ferromagnetic layer 15 are antiferromagnetically coupled. Both the ferromagnetic layer 14 on one side and the ferromagnetic layer 15 on the other side are preferably 1 nm or less.
- a magnetoresistive element 30 according to the second embodiment is formed by laminating an Ir layer 12 and a Pt layer 13 one by one, and further laminating one ferromagnetic layer 14 and the other ferromagnetic layer 15 above and below them.
- a first non-magnetic layer 20 is provided between the heavy metal layer 11 and the recording layer 16, and the crystal structure of the heavy metal layer 11 and the recording layer 16 is divided.
- a second nonmagnetic layer 21 is provided on the side of the second ferromagnetic layer opposite to the barrier layer 17 in the reference layer 18 adjacent to the barrier layer 17 . It breaks the crystal structure of the layer.
- One or more elements are selected from W, Ta, Mo, Hf, and the like for the first nonmagnetic layer 20 and the second nonmagnetic layer 21 .
- (Co/Pt) n /Ir/(Co/Pt) m is formed on the side opposite to the second ferromagnetic layer with the second nonmagnetic layer 21 interposed therebetween.
- a pinned layer 22 is provided to fix and pin the direction of the magnetization M12 of the second ferromagnetic layer of the reference layer 18 .
- the combination of the second ferromagnetic layer and the pinned layer 22 may be called a reference layer.
- the above m and n are arbitrary natural numbers.
- FIG. 11 is a cross-sectional view of a magnetoresistive element 30 according to a third embodiment of the invention.
- the heavy metal layer 11 is formed by laminating an Ir layer 12 and a Pt layer 13 one by one.
- the other ferromagnetic layer 15 is provided correspondingly.
- the magnetization M21 of one ferromagnetic layer 14 and the magnetization M22 of the other ferromagnetic layer 15 are both in opposite directions. That is, when the buffer layer 2 is provided on the substrate 1 as necessary and the heavy metal layer 11 is provided thereon, one ferromagnetic layer 14 is provided on the substrate 1 or buffer layer 2 side of the heavy metal layer 11 .
- the other ferromagnetic layer 15 is provided on the recording layer 16 side.
- the reason why the Ir layer 12 and the Pt layer 13 are one layer each is that the ferromagnetic layer 14 on one side and the ferromagnetic layer 15 on the other side are antiferromagnetically coupled.
- the recording layer 16 and the reference layer 18 are also preferably horizontally magnetized layers. .
- the spin Hall effect causes the ferromagnetic layer 14 on the other side to flow.
- the magnetizations of the magnetic layer 14 and the ferromagnetic layer 15 are reversed, and under the influence of the magnetization reversal of the ferromagnetic layer 14 and the ferromagnetic layer 15, the magnetization of the recording layer 16 is reversed. As shown on the left side of FIG.
- the magnetization M21 of one ferromagnetic layer 14 and the magnetization M22 of the other ferromagnetic layer 15 are reversed.
- the direction of magnetization M11 is reversed.
- the magnetization M21 of one ferromagnetic layer 14 and the magnetization M22 of the other ferromagnetic layer 15 are reversed by applying a write current Iw in the -x direction, thereby resulting in the state shown on the right side of FIG. , the direction of the magnetization M11 of the recording layer 16 is reversed.
- the preferred thicknesses of the Ir layer 12 and the Pt layer 13 of the heavy metal layer 11 are the same as in the second embodiment.
- on the side opposite to the second ferromagnetic layer with the second nonmagnetic layer 21 interposed therebetween for example, (Co/Pt) n /Ir/(Co/Pt) m is formed.
- a pinned layer 22 is provided to fix and pin the direction of the magnetization M12 of the second ferromagnetic layer of the reference layer 18 .
- the combination of the second ferromagnetic layer and the pinned layer 22 may be called a reference layer.
- the above m and n are arbitrary natural numbers.
- a magnetoresistive element 30 according to the third embodiment is formed by laminating an Ir layer 12 and a Pt layer 13 one by one, and further laminating one ferromagnetic layer 14 and the other ferromagnetic layer 15 above and below them.
- FIG. 13 is a perspective view schematically showing a magnetoresistive element 50 according to the fourth embodiment.
- 14 is a plan view of the third terminal T3 shown in FIG. 13.
- the magnetoresistive element 50 according to the fourth embodiment differs from the magnetoresistive element 10 according to the first embodiment in the following points. That is, the recording layer 16, the barrier layer 17, and the reference layer 18 do not have a cylindrical shape, but have a notch NA that is cut in the plane 5 extending along the z-axis while being inclined with respect to the x-axis and y-axis.
- the shape of the recording layer 16, the barrier layer 17, and the reference layer 18 when viewed in the stacking direction of the heavy metal layer 11, that is, the shape in a plan view, corresponds to the direction in which the write current flows in the heavy metal layer 11. It is asymmetric with respect to any line.
- the direction in which precession is likely to occur is determined.
- the magnetization direction of the recording layer 16 can be reversed and maintained without applying an external magnetic field.
- Materials and thicknesses of the recording layer 16, the barrier layer 17, the reference layer 18, the cap layer 19, and the terminals constituting the MTJ are the same as in the first embodiment. Moreover, it is applied not only to the first embodiment but also to the second and third embodiments.
- FIG. 15 is a perspective view schematically showing a magnetic memory 60 according to the fifth embodiment of the invention.
- a plurality of magnetoresistive elements are arranged above or below the same heavy metal layer 11a. They are arranged in an array on 11b and 11c.
- one unit 61 is constructed by arranging a plurality of magnetoresistive elements M11, M12, M13, M14, and M15, for example, a total of five on one heavy metal layer 11a.
- Each of the magnetoresistive elements M11 to M15 is constructed by laminating a recording layer 16, a barrier layer 17, a reference layer 18, a cap layer 19 and a terminal in this order.
- One unit 61 is provided with a first common terminal (not shown) and a second common terminal (not shown) with respect to the heavy metal layer 11 with a plurality of magnetoresistive effect elements M11 to M15 interposed therebetween, Either the source or the drain of the first transistor Tr11 is connected to the first common terminal so that a write voltage can be applied thereto, and the second common terminal is the source or drain of the second transistor Tr12. Either one is connected, for example, to ground.
- the magnetoresistive elements M11, M12, M13, M14 and M15 are the same as described in the first embodiment with reference to FIGS.
- a heavy metal layer 11a, a recording layer 16, a barrier layer 17, and a reference layer 18 are included, and the recording layer 16 is disposed on the side opposite to the reference layer 18 with the barrier layer 17 interposed therebetween, that is, on the side of the heavy metal layer 11a.
- the reference layer 18 is arranged on the opposite side of the heavy metal layer 11a with the barrier layer 17 interposed therebetween.
- the recording layer 16, the barrier layer 17 and the reference layer 18 form a magnetic tunnel junction (MTJ).
- MTJ magnetic tunnel junction
- the magnetoresistive elements M11, M12, M13, M14, and M15 generate the first ferromagnetism in the recording layer 16 using spin-orbit torque-induced magnetization reversal by a current (referred to as "write current") flowing through the heavy metal layer 11a.
- write current a current flowing through the heavy metal layer 11a.
- the direction of magnetization in the layer is reversed.
- the recording layer 16, the barrier layer 17, and the reference layer 18 have a columnar shape in accordance with the shape of the recording layer 16, and are symmetrical about the direction (z direction) seen in plan view. It has become. That is, the recording layer 16, the barrier layer 17, and the reference layer 18 are line-symmetrical with respect to any line in the direction of the current flowing through the heavy metal layer 11a. This also applies to units 62 and 63, which will be described later.
- the magnetic memory 60 has a plurality of magnetoresistive elements M21, M22, M23, M24, and M25 on one heavy metal layer 11b.
- One unit 62 is formed by arranging a plurality of magnetoresistive elements M31, M32, M33, M34, and M35 on one heavy metal layer 11c.
- the effect elements M21 to M25 and M31 to M35 are constructed by laminating a recording layer 16, a barrier layer 17, a reference layer 18, a cap layer 19 and terminals in this order.
- Each of the units 62 and 63 connects a first common terminal (not shown) and a second common terminal (not shown) to the corresponding heavy metal layers 11b and 11c to a plurality of magnetoresistive elements M21 to M25 and M31. , M35 are interposed therebetween, one of the sources and drains of the first transistors Tr21 and Tr31 is connected to the first common terminal, and a write voltage can be applied thereto. is connected to one of the sources and drains of the second transistors Tr22 and Tr32, and is connected to the ground, for example.
- the magnetic memory 60 is configured by arranging units 61, 62, and 63.
- FIG. The fifth embodiment relates to an array of 5 ⁇ 3 magnetoresistive elements as shown, but is not limited to this, and can be applied to an array in which m ⁇ n magnetoresistive elements are integrated.
- a magnetic memory 60 according to the fifth embodiment includes a writing unit (not shown) having a writing power supply for writing data to the magnetoresistive elements M11 to M35.
- the writing unit writes data to the magnetoresistive elements M11 to M35 by applying a write current Iw to the heavy metal layers 11a, 11b, and 11c.
- the magnetic memory 60 includes a read power source and a current detector (both not shown), and a read section for reading data from the magnetoresistive elements M11 to M35.
- a read power supply supplies a read current Ir passing through the barrier layer 17 .
- the current detector detects a read current Ir passing through the barrier layer 17 and reads data written in the magnetoresistive elements M11 to M35.
- a method of writing data to the magnetoresistive elements M11 to M35 will be described.
- a case where the second common terminals T12, T22, T32 of the heavy metal layers 11a, 11b, 11c are grounded will be described, but they may be grounded via the second transistors Tr12, Tr22, Tr32.
- you can stay As an initial state the first transistors Tr11, Tr21, Tr31 connected to the first common terminals T11, T21, T31 of the heavy metal layers 11a, 11b, 11c and the third terminals T131 to T135, T231 to Assume that the third transistors Tr131 to Tr135, Tr231 to Tr235, Tr331 to Tr335 connected to T235 and T331 to T335 are all off.
- an MTJ to which data "1" is to be written is selected by turning on the third transistor Tr131 connected to the third terminal (for example, T131) of the MTJ.
- the write voltage Vw is set to a negative voltage
- the first transistor Tr11 connected to the first common terminal T11 is turned on
- the write current Iw is supplied from the second common terminal T12 to the first common terminal T11. flush. Since the magnetic anisotropy of the recording layer 16 is small only in the MTJ in which the third transistor Tr131 connected to the third terminal T131 is turned on, the magnetization is reversed. As a result, data "1" is written only to the selected MTJ. After that, the third transistor (Tr131 in this case) that is on is turned off, the first transistor Tr11 connected to the first common terminal T11 is turned off, and the write operation ends.
- the read operation is performed by turning on the first transistor Tr11 connected to the first common terminal (for example, T11) of the MTJ to be read, and then turning on the transistor Tr11 connected to the third terminal (for example, T132) of the MTJ to be read. This is done by turning on the third transistor Tr132 and applying a read current Ir to the MTJ to be read.
- the subsequent read operation is the same as in the first embodiment.
- a magnetic memory 60 according to the fifth embodiment of the present invention is formed by stacking an Ir layer 12 and a Pt layer 13, facing a heavy metal layer 11 with a ferromagnetic layer 15 interposed therebetween, and having reversible magnetization.
- the heavy metal layer 11 is provided with lamination of the Ir layer 12 and the Pt layer 13 between the ferromagnetic layer 14 on one side and the ferromagnetic layer 15 on the other side.
- a plurality of magnetoresistive elements each including the recording layer 16, the barrier layer 17 and the reference layer 18 may be provided on the same heavy metal layers 11a, 11b and 11c.
- the MTJ is not limited to the cylindrical shape, and may have the notch NA as in the fourth embodiment.
- FIG. 16 is a diagram showing an outline of an AI system according to the sixth embodiment of the present invention.
- Cross-point memories (CM 11 , . . . , CM mn ) connecting the first wires (S 1 , . is provided.
- the cross-point memory (CM 11 , . . . , CM mn ) is composed of storage elements such as ReRAM (resistance change memory), PCM (phase change memory), and MTJ.
- a resistive crossbar network is provided.
- An input line INPUT is connected to one end of the first wiring (S 1 , . . . , S n ), and an electronic neuron (NR 1 , . ing. Electronic neurons (NR 1 , . . . , NR n ) are formed on neuron substrates (SA NR1 , . . . , SA NRn ).
- a neuron substrate (SA NR1 , . Electronic neurons (NR 1 , . . . , NR n ) have the same configuration as the magnetoresistive effect elements according to the first to fourth embodiments of the present invention.
- An output line OUTPUT is connected to the neuron boards (SA NR1 , . . . , SA NRn ).
- the magnetoresistive elements 10 are used for electronic neurons (NR 1 , . . . , NR n ), and electronic neurons (NR 1 , . . . , NR n ). is the weighted sum of the resistive crossbar network.
- An artificial intelligence (AI) system is configured such that the resistance crossbar network is one stage, which are connected in multiple stages, and the output of the resistance crossbar network of the previous stage is input to the resistance crossbar network of the next stage.
- Crosspoint memories (CM 11 , . . . , CM mn ) correspond to synapses in AI systems.
- the cross-point memories (CM 11 , . . . , CM mn ) store data with a set of memories corresponding to a pair of second wirings. For example, when there is an input from the resistor crossbar network in the previous stage, VS is input to the second wiring B1 and -VS is input to the second wiring B2 according to the input. In response, data are stored in the cross-point memory CM 11 and the cross-point memory CM 21 , respectively. Data is stored in the cross-point memory CM31 and the cross-point memories subsequent to the cross-point memory CM41 in accordance with the input from the resistance crossbar network of the previous stage.
- a sum signal ie, a signal corresponding to the sum of the readout currents from each cross-point memory (CM 11 , . . . , CM m1 ), is output to the electronic neuron NR 1 and stored.
- data is similarly stored in the crosspoint memories (CM1n , . , CM mn ) is output to the electronic neuron NR n and stored.
- the data stored in the electronic neurons (N 1 , . . . , NR n ) are configured to be input to the resistive crossbar network of the next stage.
- FIG. 17 is a circuit diagram of an example of an AI system using magnetoresistive elements. It has a configuration in which a reference element REF is connected in series to an electronic neuron NRn to be read.
- the reference element REF is composed of a magnetoresistive effect element similar to the electron neuron NRn , and has a predetermined resistance value.
- the reference element REF receives the power supply voltage V DD through the transistor TR SIG , and the electronic neuron NR n is grounded.
- the read enable signal SIG is input and the transistor TR SIG is turned on, the power supply voltage V DD is input to the reference element REF.
- the magnetoresistive effect element according to the embodiment of the present invention is used so that the output of the preceding-stage resistive crossbar network is input to the succeeding-stage resistive crossbar network, thereby constituting an AI system. be done.
- FIG. 18 is a diagram showing an outline of an AI system different from that in FIG.
- the electron neurons (NR 1 , . . . , NR n ) have the same configuration as the magnetoresistive effect element according to the embodiment of the present invention, and the cross-point memory (CM 11 , . . . , CM mn ) , CM mn ) provided with cross-point memories (CM 11 , . . . , CM mn ) are common substrates (SA 1 , .
- the magnetoresistive effect element according to the embodiment of the present invention is used so that the output of the preceding-stage resistive crossbar network is input to the succeeding-stage resistive crossbar network, thereby constituting an AI system. be done.
- FIG. 19 is a plan view of an AI system according to the sixth embodiment of the invention.
- Magnetic field applying electrodes (CL1, CL2, . may As shown in FIG. 19, the magnetic field applying electrodes (CL1, CL2, .
- the write current Iw is applied to the position of the magnetoresistive element to be written on the heavy metal wiring, the magnetoresistive element has a small thermal stability constant, so "1" and "0" are not defined. In this state, for example, a current is passed through the magnetic field applying electrodes (CL1, CL2, .
- FIG. 20 is a plan view of the AI system according to the sixth embodiment of the present invention, which is different from FIG. In FIG. 20, the semi-arc wiring portion of the magnetic field applying electrode CL1 and the semi-arc wiring portion of the magnetic field applying electrode CL2 are alternately arranged on both sides in the wiring extending direction.
- the magnetic field applying electrode CL1 and the magnetic field applying electrode CL2 are supplied with a current in a predetermined direction, a magnetic field is generated in a predetermined direction according to the current flow, and writing is performed.
- a sample 100 includes a Si substrate 101 provided with a thermal oxide film, a Ta layer 102 with a thickness of 0.5 nm provided on the thermal oxide film, and a CoFeB layer 102 with a thickness of 1.5 nm provided on the Ta layer 102 .
- It is composed of a layer 103 , a heavy metal layer 104 in which a Pt layer and an Ir layer are repeatedly laminated, and a Ta layer 105 having a thickness of 1.0 nm on the uppermost surface of the heavy metal layer 104 .
- the heavy metal layer 104 is composed of a laminate of a Pt layer with a thickness of 0.4 nm and an Ir layer with a thickness of 0.4 nm. Two to ten layers of Pt/Ir were laminated so as to have a thickness of 6 nm to 8.0 nm.
- the heavy metal layer 104 is composed of a stack of a Pt layer with a thickness of 0.6 nm and an Ir layer with a thickness of 0.6 nm, and the thickness of the entire heavy metal layer 104 is 1.6 nm.
- One to seven layers of Pt/Ir were laminated so as to have a thickness of 2 nm to 8.4 nm.
- the heavy metal layer 104 is composed of a laminate of a Pt layer with a thickness of 0.8 nm and an Ir layer with a thickness of 0.8 nm.
- a Pt layer with a thickness of 0.8 nm and an Ir layer with a thickness of 0.8 nm One to six layers of Pt/Ir were laminated so as to have a thickness of 6 nm to 9.6 nm, respectively.
- the heavy metal layer 104 is composed of a laminate of a Pt layer with a thickness of 1.0 nm and an Ir layer with a thickness of 0.8 nm, and the thickness of the entire heavy metal layer 104 is 1.0 nm.
- One to five layers of Pt/Ir were laminated so as to have a thickness of 8 nm to 9.0 nm.
- the heavy metal layer 104 consisted of a stack of a Pt layer with a thickness of 1.2 nm and an Ir layer with a thickness of 0.8 nm, and the thickness of the entire heavy metal layer was 2.0 nm.
- One to five layers of Pt/Ir were laminated so as to have a thickness of 10.0 nm to 10.0 nm.
- the heavy metal layer 104 consisted of a stack of a Pt layer with a thickness of 0.8 nm and an Ir layer with a thickness of 0.6 nm, and the thickness of the entire heavy metal layer was 1.4 nm.
- One to five layers of Pt/Ir were laminated so as to have a thickness of ⁇ 7.0 nm, respectively.
- the heavy metal layer 104 is composed of a laminate of a Pt layer with a thickness of 1.0 nm and an Ir layer with a thickness of 0.6 nm, and the thickness of the entire heavy metal layer is 1.6 nm.
- One to five layers of Pt/Ir were laminated so as to have a thickness of 8.0 nm to 8.0 nm, respectively.
- the heavy metal layer 104 is composed of a laminate of a Pt layer with a thickness of 1.2 nm and an Ir layer with a thickness of 0.6 nm, and the thickness of the entire heavy metal layer is 1.8 nm.
- One to five layers of Pt/Ir were laminated so as to have a thickness of .about.9.0 nm, respectively.
- heavy metal layers 104 each consisting of only a Pt layer with a thickness between 1.5 nm and 7.0 nm were fabricated.
- FIG. 22 is a diagram showing heavy metal layer thickness dependence of electrical conductivity of the third sample.
- the third sample has a stack of Ta 0.5 nm/CoFeB 1.5 nm/(Pt 0.8 nm/Ir 0.8 nm) n /Ta( ⁇ 0) 1 nm, where n is 1-5.
- the specific resistance ⁇ PtIr of the heavy metal layer was 44.56 ⁇ cm.
- the specific resistance ⁇ CoFeB of CoFeB was 260.5 ⁇ cm.
- FIG. 23 is a diagram showing heavy metal layer thickness dependence of electrical conductivity of the fourth sample.
- the fourth sample is a stack of Ta 0.5 nm/CoFeB 1.5 nm/(Pt 1.0 nm/Ir 0.8 nm) n /Ta( ⁇ 0) 1 nm, where n is 1-5.
- the specific resistance ⁇ PtIr of the heavy metal layer was 37.21 ⁇ cm.
- the specific resistance ⁇ CoFeB of CoFeB was 260.5 ⁇ cm.
- FIG. 24 is a diagram showing heavy metal layer thickness dependence of the electrical conductivity of the fifth sample.
- the fifth sample is a stack of Ta 0.5 nm/CoFeB 1.5 nm/(Pt 1.2 nm/Ir 0.8 nm) n /Ta( ⁇ 0) 1 nm, where n is 1-5.
- the specific resistance ⁇ PtIr of the heavy metal layer was 36.9992 ⁇ cm.
- the specific resistance ⁇ CoFeB of CoFeB was 260.5 ⁇ cm.
- the electrical conductivity has linearity with respect to the thickness t of the heavy metal layer 104.
- FIG. It was also found that the specific resistance ⁇ PtIr of the heavy metal layer decreases as the ratio of the thickness of the Pt layer to the thickness of the Ir layer constituting the laminated film (t_Pt/t_Ir) increases.
- FIG. 25 shows the results of the specific resistance obtained from the thickness dependence of the electrical conductivity of the heavy metal layer 104 for the first to fifth samples.
- the spin generation efficiency ⁇ SH and the spin conductivity ⁇ SH of the magnetic laminated film were obtained.
- the results are shown in FIGS. 26 and 27.
- FIG. 26 and 27 also show the results of the comparative sample and the results of the ninth sample.
- the horizontal axis of FIG. 26 indicates the film thickness ratio of the Pt layer and the Ir layer in each sample, and the vertical axis indicates the spin generation efficiency ⁇ SH .
- the spin generation efficiency ⁇ SH is lower than that of the Pt single layer.
- the values are at the same level as the Pt single layer.
- the horizontal axis of FIG. 27 indicates the film thickness ratio of the Pt layer and the Ir layer in each sample, and the vertical axis indicates the spin conductivity ⁇ SH .
- the spin conductivity ⁇ SH is lower than that of the Pt single layer. It was found that the thicknesses of 0.8/0.8, 1.0/0.8 and 1.2/0.8 were higher than the Pt single layer.
- FIGS. 28 to 30 show the third to fifth samples.
- the horizontal axis is the thickness ratio of the Pt layer and the Ir layer in each sample
- the vertical axis is the spin generation efficiency ⁇ SH in FIG. 28, the specific resistance ⁇ XX in FIG. 29, and the spin conductivity ⁇ SH in FIG. is.
- the case where the Ir layer has a thickness of 0.8 nm is plotted with black circles ( ⁇ ), and the case where the Ir layer has a thickness of 0.6 nm is plotted with diamonds ( ⁇ ).
- the spin generation efficiency ⁇ SH increases as the Pt layer thickness increases to 0.8 nm, 1.0 nm, and 1.2 nm, regardless of whether the Ir layer thickness is 0.6 nm or 0.8 nm.
- the thickness t_Ir of the Ir layer is 0.6 nm and 0.8 nm
- the thickness t_Pt of the Pt layer is 0.8, 1.0, and 1.2 nm, respectively, compared with the case of using Pt alone (about 0.1).
- a sufficient spin generation efficiency ⁇ SH can be obtained in the range of .
- the spin generation efficiency ⁇ SH is about 0.07, which is not very preferable.
- the specific resistance ⁇ xx decreases as the Pt layer thickness increases to 0.8 nm, 1.0 nm, and 1.2 nm, regardless of whether the Ir layer thickness is 0.6 nm or 0.8 nm.
- the thickness t_Ir of the Ir layer is 0.6 nm and 0.8 nm and the thickness t_Pt of the Pt layer is 0.8, 1.0 and 1.2 nm.
- a low resistivity ⁇ xx is obtained.
- the resistivity ⁇ xx is about 50 ⁇ cm, which is not very preferable.
- the spin conductivity ⁇ SH increases as the thickness of the Pt layer increases to 0.8 nm, 1.0 nm, and 1.2 nm, regardless of whether the thickness of the Ir layer is 0.6 nm or 0.8 nm.
- the thickness t_Pt of the Pt layer is 0.55 ⁇ 10 5 ⁇ ⁇ 1 m ⁇ 1 when the thickness t_Ir of the Pt layer is 0.6 nm and 0.8 nm.
- High spin conductivity ⁇ SH is obtained in the range of 8, 1.0, 1.2 nm.
- the spin conductivity ⁇ SH is approximately 1.4 ⁇ 10 5 ⁇ ⁇ 1 m ⁇ 1 , which is not very preferable.
- each Ir layer constituting the heavy metal layer is preferably 0.6 nm or more.
- the thickness of the Pt layer constituting the heavy metal layer is preferably greater than 0.6 nm per layer.
- the thickness ratio of the Pt layer and the Ir layer in the heavy metal layer is preferably in the range of 1:0.5 to 1:0.8.
- the heavy metal layer as a whole preferably has a thickness of 10 nm or less. It is sufficient for the thickness of the heavy metal layer to be about 3 to 4 times the spin diffusion length, and it may be thin as long as current can flow. This is because even if it is made thicker than necessary, it does not affect the recording layer. 6)
- Each of the Pt layer and the Ir layer constituting the heavy metal layer includes one layer, and may be, for example, a Pt layer/Ir layer/Pt layer or an Ir layer/Pt layer/Ir layer.
- FIG. 21J is a cross-sectional view of the manufactured ninth sample.
- a ninth sample 100 includes a Si substrate 111 with a thermal oxide film, a Ta layer 112 with a thickness of 0.5 nm provided on the thermal oxide film, and a CoFeB substrate with a thickness of 1.5 nm provided on the Ta layer 112. a layer 113, a MgO layer 114 with a thickness of 1.2 nm provided on the CoFeB layer 113, and a heavy metal layer 115 in which a Pt layer with a thickness of 1.0 nm and an Ir layer with a thickness of 0.8 nm are repeatedly laminated.
- the heavy metal layer 115 is composed of a stack of a Pt layer with a thickness of 1.0 nm and an Ir layer with a thickness of 0.8 nm. One to six layers were laminated, respectively.
- FIG. 31 is a diagram showing heavy metal layer thickness dependence of electrical conductivity of the ninth sample.
- the ninth sample is Ta 0.5 nm/CoFeB 1.5 nm/MgO 1.2 nm/(Pt 1.0 nm/Ir 0.8 nm) n /CoFeB 1.5 nm/MgO 1.5 nm/Ta(-0) 1 nm.
- the specific resistance ⁇ PtIr of the heavy metal layer was 34.016 ⁇ cm.
- the specific resistance ⁇ CoFeB of CoFeB was 260.5 ⁇ cm.
- the spin generation efficiency ⁇ SH and the spin conductivity ⁇ SH were determined.
- the pinhole generation efficiency ⁇ SH is about 0.1
- the resistivity ⁇ PtIr is 35 ⁇ cm
- the spin conductivity ⁇ SH is 3.2 ⁇ 10 5 ⁇ ⁇ 1 m ⁇ 1 .
- the value is more preferable as a magnetic laminated film (heavy metal layer).
- the value of the specific resistance ⁇ obtained for the ninth sample is compared with the results of other samples from FIG. is reduced to 35 ⁇ cm and found to be favorable.
- the value of the spin Hall angle ⁇ SH obtained for the ninth sample shows that when compared with the results of the first to fifth samples shown in FIG. , the spin Hall angle ⁇ SH increases to 0.108, which is preferable. Note that the spin Hall angle of the Ir single layer is very small, and is reported to be 0.01 (PHYSICAL REVIEW B99, 134421, 2019).
- the value of the spin conductivity ⁇ SH obtained for the ninth sample is compared with the results for the first to fifth samples shown in FIG. It was found that the spin conductivity ⁇ SH increased up to 3.2 ⁇ 10 5 ⁇ ⁇ 1 m ⁇ 1 by providing it.
- the pinhole generation efficiency ⁇ SH , specific resistance ⁇ PtIr , and spin conductivity ⁇ SH of the ninth sample are favorable. It has been found that it is preferable to provide CoFeB on top and bottom. Also, it is considered that the provision of the MgO layer allows the Pt layer or the Ir layer adjacent to the MgO layer to have crystallinity.
- FIG. 32 is a diagram showing the dependence of the electrical conductivity on the thickness of the heavy metal layer.
- the horizontal axis is the thickness of the heavy metal layer, and the vertical axis is the electrical conductivity Gxx ( ⁇ ⁇ 1 ).
- Square ( ⁇ ) plots, diamond ( ⁇ ) plots, and circle ( ⁇ ) plots indicate that the samples are CoFeB/MgO/(Pt1.0/Ir0.8) n , (Pt1.0/Ir0.8) n , is Pt. It was found that the specific resistances of Pt, (Pt1.0/Ir0.8) n , and MgO/(Pt1.0/Ir0.8) n decreased in order from 64.8 ⁇ cm, 37.2 ⁇ cm, and 34.0 ⁇ cm. .
- the heavy metal layer 11 is constructed by providing one ferromagnetic layer 14 and the other ferromagnetic layer 15 of Co above and below the Pt layer 13 /Ir layer 12 .
- Co/Ir/Co it is generally known that strong antiferromagnetic coupling occurs between Co—Co through Ir.
- Ir has a very low spin generation efficiency ⁇ SH and cannot be used as a heavy metal.
- the Pt layer 13/Ir layer 12 provides a high spin generation efficiency ⁇ SH and a high spin conductivity ⁇ SH .
- a Co layer is provided on the Pt/Ta underlayer, an Ir layer and a Pt layer are provided in this order on the Co layer, a Co layer is provided on the Pt layer, and the Pt layer is used as a cap layer.
- a sample was prepared to investigate the interlayer magnetic coupling between the Ir/Pt spacers. Note that a plurality of samples of the Pt layer were manufactured with a thickness between 0.6 nm and 1.0 nm.
- FIG. 33 shows the results of examining the interlayer magnetic coupling between the Ir/Pt spacers of the tenth sample, where the horizontal axis represents the thickness tIr of the Ir layer and the vertical axis represents the interlayer coupling force J ex . From FIG. 33, strong antiferromagnetic coupling was confirmed also through the Ir/Pt spacer.
- n is 1 or more and 5 or less, including the case where n is 1), and furthermore, this Co/Ir/Pt/Co
- the electrodes since the ferromagnetic layers Co are provided above and below the Ir/Pt, as shown in FIG.
- the film thickness of Ir is preferably 0.45 to 0.65 nm and 1.3 to 1.5 nm for antiferromagnetic (AF) coupling.
- the Pt layer is preferably 0.6-1.0 nm.
- Co is preferably 1 nm or less.
- Table 1 shows spin generation efficiency ⁇ SH , specific resistance ⁇ ( ⁇ cm), and spin conductivity ⁇ SH when the interface between the heavy metal layer and the recording layer is a Pt layer or an Ir layer. From Table 1, it was found that the interface between the heavy metal layer and the recording layer is preferably formed by the Pt layer rather than by the Ir layer. From this, it can be said that the interface between the heavy metal layer 11 and the recording layer side is preferably formed of a Pt layer in each of the above-described embodiments.
- Table 2 summarizes the relative values of power consumption according to the structure of the heavy metal layer. From Table 2, the thickness ratios of the Pt layer and the Ir layer are 0.4 nm/0.4 nm, 0.6 nm/0.6 nm, 0.8 nm/0.8 nm, 1.0 nm/0.8 nm, and 1 It was found that the power consumption decreased relatively greatly as the thickness became 0.2 nm/0.8 nm. Furthermore, it was found that the power consumption was relatively reduced from 0.33 to 0.26 by providing the magnetic layers CoFeB on both sides and sandwiching the MgO layers.
- FIG. 34 is a diagram schematically showing a Hall bar and a measurement system fabricated as the 11th sample.
- FIG. 35A is a cross-sectional view of the fabricated 11th sample.
- the eleventh sample includes a Si substrate 201 provided with a thermal oxide film, a Ta layer 202 having a thickness of 3 nm provided on the thermal oxide film, and a heavy metal layer 202 provided on the Ta layer 202.
- 203 a heavy metal layer 203 in which four layers of Pt layers with a thickness of 1.0 nm and Ir layers with a thickness of 0.8 nm are alternately laminated, and a Co layer 204 with a thickness of 1.3 nm provided on the heavy metal layer 203.
- an Ir layer 205 with a thickness of 0.6 nm provided on the Co layer 204 an Ir layer 205 with a thickness of 0.6 nm provided on the Co layer 204, a Pt layer 206 with a thickness of 0.6 nm provided on the Ir layer 205, and a Ta layer with a thickness of 3 nm provided on the Pt layer 206.
- FIG. 35B is a cross-sectional view of another manufactured comparative sample.
- Another comparative sample as shown in FIG. A 7.2 nm thick Pt layer 203a, a 1.3 nm thick Co layer 204 provided on the Pt layer 203a, a 0.6 nm thick Ir layer 205 provided on the Co layer 204, and a It was composed of a Pt layer 206 with a thickness of 0.6 nm and a Ta layer 207 with a thickness of 3 nm provided on the Pt layer 206 .
- FIG. 36 is a diagram showing the pulse current dependence of the Hall resistance R xy ( ⁇ ) of the first sample and another comparative sample.
- the horizontal axis is the pulse current I (mA)
- the vertical axis is the Hall resistance R xy ( ⁇ ).
- the reversal current when the heavy metal layer 203 uses the multilayer film electrode of the Pt layer and the Ir layer is It turned out that it is about 70% smaller than the reversal current of .
- the thickness of the Pt layer and the Ir layer that constitute the heavy metal layer may be constant or different for each Pt layer and Ir layer.
- either perpendicular magnetization or in-plane magnetization may be used.
- the magnetoresistive element according to the embodiment of the present invention is manufactured by sequentially depositing each element using sputtering or the like, and performing heat treatment while applying a magnetic field in the desired direction of magnetization.
- Substrate 2 Buffer layers 10, 30, 50: Magnetoresistive element 11: Heavy metal layer 12: Ir layer 13: Pt layer 14: One ferromagnetic layer 15: The other ferromagnetic layer 16: Recording layer 17: Barrier Layer 18: Reference Layer 19: Cap Layer 60: Magnetic Memory
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Abstract
Description
[1] Ir層とPt層とを積層してなる重金属層と、
前記重金属層に対向するように設けられ、反転可能な磁化を有する第1の強磁性層を含んでなる記録層と、
磁化の方向が固定された第2の強磁性層を含んでなる参照層と、
前記第1の強磁性層と前記第2の強磁性層とに挟まれ、絶縁体で構成されてなる障壁層と、
を備え、
前記重金属層に流れる書き込み電流により、前記第1の強磁性層における磁化の方向が反転する、磁気抵抗効果素子。
[2] 前記重金属層は前記Ir層と前記Pt層とを繰り返し積層してなる、前記[1]に記載の磁気抵抗効果素子。
[3] 前記重金属層において最も外側の前記Pt層が前記記録層と界面を形成する、前記[1]又は[2]に記載の磁気抵抗効果素子。
[4] 前記重金属層の前記Pt層が、一層当たり、0.6nmよりも長く1.5nm以下の厚みを有する、前記[1]乃至[3]の何れか1項に記載の磁気抵抗効果素子。
[5] 前記重金属層の前記Ir層が、一層当たり、0.6nm以上1.5nm以下の厚みを有する、前記[1]乃至[4]の何れか1項に記載の磁気抵抗効果素子。
[6] 前記重金属層における前記Pt層と前記Ir層との厚みの比が、1:0.5~1:0.8の範囲である、前記[1]乃至[5]の何れか1項に記載の磁気抵抗効果素子。
[7] 前記重金属層は、前記Ir層と前記Pt層とを一層ずつ積層し、かつ前記記録層側と前記記録層の逆側とにそれぞれ別の強磁性層を設けてなる、前記[1]に記載の磁気抵抗効果素子。
[8] 前記記録層、前記障壁層及び前記参照層の、前記重金属層の積層方向に向かってみた形状が、前記重金属層での前記書き込み電流に沿った方向の何れの線に対しても非対称である、前記[1]乃至[7]の何れか1項に記載の磁気抵抗効果素子。
[9] 前記記録層、前記障壁層及び前記参照層の、前記重金属層の積層方向に向かってみた形状が、前記重金属層での前記書き込み電流に沿った方向の何れかの線に対して対称である、前記[1]乃至[7]の何れか1項に記載の磁気抵抗効果素子。
[10] それぞれが前記記録層と前記障壁層と前記参照層とを含む、前記[1]乃至[9]の何れか1項に記載の磁気抵抗効果素子が複数、同一の前記重金属層に設けられている、磁気メモリ。
[11]前記[1]乃至[7]の何れか1項に記載の磁気抵抗効果素子が、抵抗クロスバーネットワークの加重和が入力される電子ニューロンに用いられる、人工知能システム。
[12]前記磁気抵抗効果素子が、抵抗クロスバーネットワークのクロスポイントメモリに用いられている、前記[11]に記載の人工知能システム。
図1は本発明の第1の実施形態に係る磁気抵抗効果素子10を模式的に示す斜視図であり、図2は図1に示す磁気抵抗効果素子10の断面図である。本発明の第1の実施形態に係る磁気抵抗効果素子10は、重金属層11と記録層16と障壁層17と参照層18とを含んでおり、記録層16が障壁層17を挟んで参照層18と逆側、即ち、重金属層11側に配置して構成され、参照層18が障壁層17を挟んで重金属層11と逆側に配置されて構成されている。記録層16と障壁層17と参照層18とで磁気トンネル接合(Magnetic Tunnel Junction:MTJ)が構成されている。そして、磁気抵抗効果素子10は、重金属層11に流れる電流(「書き込み電流」という。)により、スピン軌道トルク(Spin Orbit Torque:SOT)誘起磁化反転を用いて、記録層16での第1の強磁性層における磁化の方向が反転するMRAM(Magnetic Random Access Memory)素子を構成する。
図9は、本発明の第2の実施形態に係る磁気抵抗効果素子30の断面図である。第2の実施形態では、図9に示すように、重金属層11は、Ir層12とPt層13とを一層ずつ積層しており、さらにその両側に、一方の強磁性層14と他方の強磁性層15が対応して設けられて構成されている。その際、一方の強磁性層14の磁化M21と他方の強磁性層15の磁化M22は、共に逆向きである。即ち、基板1上にバッファー層2を必要に応じて設け、その上に重金属層11が設けられて構成される場合において、重金属層11の基板1又はバッファー層2側に一方の強磁性層14が設けられ、記録層16側に他方の強磁性層15が設けられている。Ir層12とPt層13とが一層ずつとなっているのは、一方の強磁性層14と他方の強磁性層15とが反強磁性結合するためである。
図11は、本発明の第3の実施形態に係る磁気抵抗効果素子30の断面図である。第3の実施形態においても、第2の実施形態と同様に、重金属層11は、Ir層12とPt層13とを一層ずつ積層しており、さらにその両側に、一方の強磁性層14と他方の強磁性層15が対応して設けられて構成されている。その際、一方の強磁性層14の磁化M21と他方の強磁性層15の磁化M22は、共に逆向きである。即ち、基板1上にバッファー層2を必要に応じて設け、その上に重金属層11が設けられて構成される場合において、重金属層11の基板1又はバッファー層2側に一方の強磁性層14が設けられ、記録層16側に他方の強磁性層15が設けられている。Ir層12とPt層13とが一層ずつとなっているのは、一方の強磁性層14と他方の強磁性層15とが反強磁性結合するためである。
図13は、第4の実施形態に係る磁気抵抗効果素子50を模式的に示す斜視図である。図14は、図13に示す第3の端子T3の平面図である。第4の実施形態に係る磁気抵抗効果素子50は、第1の実施形態に係る磁気抵抗効果素子10と次の点で異なる。即ち、記録層16、障壁層17及び参照層18が円柱形状ではなく、x軸及びy軸に傾斜してz軸に沿って延びる面5で切り欠いた切り欠き部NAを有する。このように、記録層16、障壁層17及び参照層18の、重金属層11の積層方向に向かって見た形状が、即ち平面視での形状が、重金属層11での書き込み電流の流れる方向の何れの線に対して非対称である。切り欠き部NAを設けることにより歳差運動しやすい方向が決まる。外部磁場を印加することなく、記録層16の磁化方向を反転させて維持することができる。なお、MTJを構成する記録層16、障壁層17、参照層18、キャップ層19、端子などの材料、厚みは第1の実施形態と同様である。また、第1の実施形態のみならず、第2乃至第3の実施形態においても適用される。
本発明の第5の実施形態に係る磁気メモリ60について詳細に説明する。図15は、本発明の第5の実施形態に係る磁気メモリ60を模式的に示す斜視図である。第5の実施形態に係る磁気メモリ60は、第1乃至第4の実施形態とは異なり、複数の磁気抵抗効果素子が同一の重金属層11aの上下何れかに、図示の形態では重金属層11a,11b,11cの上に、アレイ状に配列されて構成されている。図15に示すように、一つの重金属層11a上に、複数個、例えば磁気抵抗効果素子M11,M12,M13,M14,M15の計5個並べられ一ユニット61が構成されている。各磁気抵抗効果素子M11乃至M15は、記録層16、障壁層17、参照層18、キャップ層19、端子の順に積層されて構成されている。一ユニット61は、重金属層11に対して第1の共通端子(図示せず)、第2の共通端子(図示せず)を複数の磁気抵抗効果素子M11~M15を挟んで設けられており、第1の共通端子には第1のトランジスタTr11のソース、ドレインの何れか一方が接続されて書き込み電圧が印加可能に設けられ、第2の共通端子には第2のトランジスタTr12のソース、ドレインの何れか一方が接続され、例えばグラウンドに接続されている。
図16は、本発明の第6実施形態に係るAIシステムの概略を示す図である。一の方向に延伸する複数本の第1の配線(S1,・・・,Sn)と、当該一の方向と直交する方向に延伸する複数本の第2の配線(B1,・・・,Bm)とを有し、第1配線(S1,・・・,Sn)と第2の配線(B1,・・・,Bm)との各交点(クロスポイント)に、第1の配線(S1,・・・,Sn)と第2の配線(B1,・・・,Bm)とを接続するクロスポイントメモリ(CM11,・・・,CMmn)が設けられている。クロスポイントメモリ(CM11,・・・,CMmn)は、ReRAM(抵抗変化メモリ)、PCM(相変化メモリ)、MTJなどの記憶素子で構成される。このようにして、抵抗クロスバーネットワークが設けられている。
次に、本発明の何れの実施形態に係る磁気抵抗効果素子で用いられる磁性積層膜について、検証実験の結果を説明する。次のような試料を作製した。図21A乃至図21Hは作製した試料の断面図である。試料100は、熱酸化膜が設けられたSi基板101と、熱酸化膜上に設けられた厚さ0.5nmのTa層102と、Ta層102上に設けられた厚さ1.5nmのCoFeB層103と、Pt層とIr層とを繰り返して積層した重金属層104と、重金属層104の最上面に厚さ1.0nmのTa層105とで構成されている。
1)重金属層として、Pt層単体よりも、Ir層とPt層とを繰り返して積層して構成した方が、比抵抗が減少するため好ましい。Ptは低抵抗であるが、グレイン成長しやすいため、薄膜状態では抵抗が高いためであり、積層構造により反転効率を下げずに比抵抗を低減することができる。
2)重金属層を構成するIr層は、一層当たり0.6nm以上の厚みがよい。
3)重金属層を構成するPt層は、一層当たり0.6nmよりも大きい厚みがよい。
一層当たりの厚さが薄いと、例えばPt層/Ir層の各厚みが0.4nmずつである場合、スピン伝導度σSHがPt単体の場合よりも悪くなるからである(図27参照)。
4)重金属層におけるPt層とIr層との厚みの比が、1:0.5~1:0.8の範囲であることが好ましい。
5)重金属層全体としては、10nm以下の厚みを有することが好ましい。重金属層の厚さは、スピン拡散長の3乃至4倍程度あれば十分であり、電流を流すことができれば薄くてもよい。必要以上に厚くしても記録層に影響しないからである。
6)重金属層を構成するPt層とIr層は何れも一層を含んでおり、例えばPt層/Ir層/Pt層でも、Ir層/Pt層/Ir層でもよい。
2:バッファー層
10,30,50:磁気抵抗効果素子
11:重金属層
12:Ir層
13:Pt層
14:一方の強磁性層
15:他方の強磁性層
16:記録層
17:障壁層
18:参照層
19:キャップ層
60:磁気メモリ
Claims (12)
- Ir層とPt層とを積層してなる重金属層と、
前記重金属層に対向するように設けられ、反転可能な磁化を有する第1の強磁性層を含んでなる記録層と、
磁化の方向が固定された第2の強磁性層を含んでなる参照層と、
前記第1の強磁性層と前記第2の強磁性層とに挟まれ、絶縁体で構成されてなる障壁層と、
を備え、
前記重金属層に流れる書き込み電流により、前記第1の強磁性層における磁化の方向が反転する、磁気抵抗効果素子。 - 前記重金属層は前記Ir層と前記Pt層とを繰り返し積層してなる、請求項1に記載の磁気抵抗効果素子。
- 前記重金属層において最も外側の前記Pt層が前記記録層と界面を形成する、請求項1又は2に記載の磁気抵抗効果素子。
- 前記重金属層の前記Pt層が、一層当たり、0.6nmよりも長く1.5nm以下の厚みを有する、請求項1乃至3の何れか1項に記載の磁気抵抗効果素子。
- 前記重金属層の前記Ir層が、一層当たり、0.6nm以上1.5nm以下の厚みを有する、請求項1乃至4の何れか1項に記載の磁気抵抗効果素子。
- 前記重金属層における前記Pt層と前記Ir層との厚みの比が、1:0.5~1:0.8の範囲である、請求項1乃至5の何れか1項に記載の磁気抵抗効果素子。
- 前記重金属層は、前記Ir層と前記Pt層とを一層ずつ積層し、かつ前記記録層側と前記記録層の逆側とにそれぞれ別の強磁性層を設けてなる、請求項1に記載の磁気抵抗効果素子。
- 前記記録層、前記障壁層及び前記参照層の、前記重金属層の積層方向に向かってみた形状が、前記重金属層での前記書き込み電流に沿った方向の何れの線に対しても非対称である、請求項1乃至7の何れか1項に記載の磁気抵抗効果素子。
- 前記記録層、前記障壁層及び前記参照層の、前記重金属層の積層方向に向かってみた形状が、前記重金属層での前記書き込み電流に沿った方向の何れかの線に対して対称である、請求項1乃至7の何れか1項に記載の磁気抵抗効果素子。
- それぞれが前記記録層と前記障壁層と前記参照層とを含む、請求項1乃至9の何れか1項に記載の磁気抵抗効果素子が複数、同一の前記重金属層に設けられている、磁気メモリ。
- 請求項1乃至7の何れか1項に記載の磁気抵抗効果素子が、抵抗クロスバーネットワークの加重和が入力される電子ニューロンに用いられる、人工知能システム。
- 前記磁気抵抗効果素子が、抵抗クロスバーネットワークのクロスポイントメモリに用いられている、請求項11に記載の人工知能システム。
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WO2016021468A1 (ja) * | 2014-08-08 | 2016-02-11 | 国立大学法人東北大学 | 磁気抵抗効果素子、及び磁気メモリ装置 |
JP2017059634A (ja) * | 2015-09-15 | 2017-03-23 | 株式会社東芝 | 磁気メモリ |
US20170229160A1 (en) * | 2016-01-20 | 2017-08-10 | The Johns Hopkins University | Heavy metal multilayers for switching of magnetic unit via electrical current without magnetic field, method and applications |
US20170330070A1 (en) * | 2016-02-28 | 2017-11-16 | Purdue Research Foundation | Spin orbit torque based electronic neuron |
JP2020155488A (ja) * | 2019-03-18 | 2020-09-24 | キオクシア株式会社 | 磁気記憶装置 |
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US11631804B2 (en) | 2018-02-13 | 2023-04-18 | Tohoku University | Magnetoresistive effect element and magnetic memory |
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JP2017059634A (ja) * | 2015-09-15 | 2017-03-23 | 株式会社東芝 | 磁気メモリ |
US20170229160A1 (en) * | 2016-01-20 | 2017-08-10 | The Johns Hopkins University | Heavy metal multilayers for switching of magnetic unit via electrical current without magnetic field, method and applications |
US20170330070A1 (en) * | 2016-02-28 | 2017-11-16 | Purdue Research Foundation | Spin orbit torque based electronic neuron |
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