WO2012002156A1 - 磁気メモリ素子、磁気メモリ - Google Patents
磁気メモリ素子、磁気メモリ Download PDFInfo
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- WO2012002156A1 WO2012002156A1 PCT/JP2011/063779 JP2011063779W WO2012002156A1 WO 2012002156 A1 WO2012002156 A1 WO 2012002156A1 JP 2011063779 W JP2011063779 W JP 2011063779W WO 2012002156 A1 WO2012002156 A1 WO 2012002156A1
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
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- H10N50/00—Galvanomagnetic devices
- H10N50/80—Constructional details
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/14—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using thin-film elements
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/161—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/165—Auxiliary circuits
- G11C11/1653—Address circuits or decoders
- G11C11/1655—Bit-line or column circuits
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/165—Auxiliary circuits
- G11C11/1659—Cell access
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
- G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
- G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
- G11C11/165—Auxiliary circuits
- G11C11/1675—Writing or programming circuits or methods
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11C—STATIC STORES
- G11C19/00—Digital stores in which the information is moved stepwise, e.g. shift registers
- G11C19/02—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements
- G11C19/08—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements using thin films in plane structure
- G11C19/0808—Digital stores in which the information is moved stepwise, e.g. shift registers using magnetic elements using thin films in plane structure using magnetic domain propagation
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- H—ELECTRICITY
- H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
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- H10N50/00—Galvanomagnetic devices
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- H—ELECTRICITY
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- H10B—ELECTRONIC MEMORY DEVICES
- H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
- H10B61/20—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors
- H10B61/22—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors of the field-effect transistor [FET] type
Definitions
- the present invention relates to a magnetic memory element, a magnetic memory, and a manufacturing method thereof.
- the present invention relates to a magnetic memory element, a magnetic memory, and a manufacturing method thereof, which are made of a material having perpendicular magnetic anisotropy using domain wall motion.
- Magnetic memory or magnetic random access memory is a non-volatile memory that can operate at high speed and can be rewritten infinitely. Development is underway.
- MRAM Magnetic Random Access Memory
- a magnetic material is used as a storage element, and information is stored in correspondence with the magnetization direction of the magnetic material.
- Several methods have been proposed as a method for switching the magnetization of the magnetic material, and all of them are common in that current is used. In practical use of MRAM, it is very important how much the write current can be reduced. According to Non-Patent Document 1, a reduction to 0.5 mA or less, more preferably a reduction to 0.2 mA or less is required.
- the minimum layout can be achieved in the 2T-1MTJ (two transistors-one magnetic tunnel junction) circuit configuration proposed in Non-Patent Document 1, and DRAM, SRAM, etc. it can be realized the existing volatile memory equal to or greater than the cost.
- the most common method of writing information to the MRAM is to arrange a wiring for writing around the magnetic memory element, and to change the magnetization direction of the magnetic memory element by a magnetic field generated by passing a current through the wiring. It is a method of switching. Since this method uses magnetization reversal by a magnetic field, writing in 1 nanosecond or less is possible in principle, which is preferable for realizing a high-speed MRAM.
- the magnetic field for switching the magnetization of the magnetic material that has ensured thermal stability and disturbance magnetic field resistance is generally about several tens of Oe (Yersted), and in order to generate such a magnetic field, about several mA. A current is required.
- the chip area is inevitably increased, and the power consumption required for writing increases, so that it is inferior in competitiveness compared to other random access memories.
- the write current further increases, which is not preferable in terms of scaling.
- the first is spin injection magnetization reversal.
- a laminated film is formed by a first magnetic layer (magnetization free layer) having reversible magnetization and a second magnetic layer (reference layer) electrically connected to and fixed in magnetization. Is done.
- Spin-polarized conduction electrons and current localization in the first magnetic layer (magnetization free layer) when a current is passed between the second magnetic layer (reference layer) and the first magnetic layer (magnetization free layer) Utilizing the interaction with electrons, the magnetization of the first magnetic layer (magnetization free layer) is reversed.
- the magnetoresistive effect developed between the first magnetic layer (magnetization free layer) and the second magnetic layer (reference layer) is used. Therefore MRAM is an element of two-terminal using spin injection magnetization inversion method.
- spin injection magnetization reversal occurs at a certain current density or higher, the current required for writing is reduced if the element size is reduced. That is, it can be said that the spin injection magnetization reversal method is excellent in scaling.
- an insulating layer is provided between the first magnetic layer (magnetization free layer) and the second magnetic layer (reference layer), and a relatively large current flows through the insulating layer during writing. Rewriting resistance and reliability are problems.
- the current path for writing and the current path for reading are the same, there is a concern about erroneous writing during reading.
- spin transfer magnetization reversal is excellent in scaling, there are some barriers to practical use.
- the second method the magnetization reversal method using the current-induced domain wall motion phenomenon
- the second method can solve the above-mentioned problem of spin injection magnetization reversal.
- An MRAM using the current-induced domain wall motion phenomenon is disclosed in Patent Document 1, for example.
- an MRAM using a current-induced domain wall motion phenomenon is fixed so that the magnetizations at both ends of the first magnetic layer (magnetization free layer) having reversible magnetization are substantially antiparallel to each other. Yes.
- a domain wall is introduced into the first magnetic layer.
- Non-Patent Document 2 when a current is passed in the direction penetrating the domain wall, the domain wall moves in the direction of conduction electrons, and therefore, in the first magnetic layer (magnetization free layer). Writing can be performed by passing an electric current through.
- a magnetic tunnel junction Magnetic Tunnel Junction; MTJ
- MTJ Magnetic Tunnel Junction
- the MRAM using the current-induced domain wall motion method becomes a three-terminal element, and is consistent with the 2T-1MTJ configuration proposed in Non-Patent Document 1 described above. Since current-induced domain wall motion also occurs when the current density is higher than a certain current density, it can be said that there is scaling as in spin injection magnetization reversal.
- the write current does not flow through the insulating layer in the magnetic tunnel junction, and the write current path and the read current path are different. For this reason, the above-mentioned problems such as those caused by spin injection magnetization reversal are solved.
- Non-Patent Document 2 requires about 1 ⁇ 10 18 [A / cm 2 ] as the current density necessary for current-induced domain wall motion.
- the write current becomes 1 mA when the width of the layer (magnetization free layer) in which the domain wall motion occurs is 100 nm and the film thickness is 10 nm. This cannot satisfy the above-mentioned conditions concerning the write current.
- Non-Patent Document 3 by using a material having perpendicular magnetic anisotropy as a ferromagnetic layer (magnetization free layer) in which current-induced domain wall movement occurs, the write current can be reduced sufficiently small. Has been reported.
- Patent Document 2 proposes a structure in which magnetization fixed layers having magnetizations antiparallel to each other are provided adjacent to both ends of a magnetization free layer in an MRAM (domain wall displacement MRAM) using current-induced domain wall motion as a writing method. Has been. With this structure, the magnetizations at both ends of the layer (magnetization free layer) where the domain wall motion occurs are fixed in the antiparallel direction, and a single domain wall is introduced.
- MRAM domain wall displacement MRAM
- the first object of the present invention is to increase the write current due to the leakage magnetic field from the magnetization fixed layer in the configuration in which the magnetization at both ends of the magnetization free layer is fixed by the magnetization fixed layer as proposed in Patent Document 2. It is an object of the present invention to provide a structure of a perpendicular magnetic domain wall motion MRAM that can prevent writing and realize writing at a low current.
- a magnetic memory element in one aspect of the present invention, includes a first magnetization free layer, a nonmagnetic layer, a reference layer, and a magnetization fixed layer.
- the first magnetization free layer is composed of a ferromagnetic material having a perpendicular magnetic anisotropy.
- the first magnetization free layer includes a first magnetization fixed region, a second magnetization fixed region, and a magnetization free region.
- the magnetization fixed layer includes at least a first magnetization fixed layer magnetically connected to the first magnetization fixed region.
- a curved portion crossing the first magnetization free layer is defined as a first boundary line
- a line segment connecting the magnetization free region and the center of the first magnetization fixed region is defined as a first line segment.
- a first displacement is present between the first boundary line and the first perpendicular line when a line segment that is a perpendicular line and is in contact with the first boundary line is defined as a first perpendicular line.
- the present invention it is possible to provide a structure of a perpendicular domain wall motion MRAM that can prevent an increase in a write current due to a leakage magnetic field from a magnetization fixed layer and can realize a write with a low current.
- the magnetic memory according to the present embodiment has a plurality of magnetic memory cells arranged in an array, and each magnetic memory cell has a magnetic memory element.
- This embodiment the magnetic memory device, the structure of a magnetic memory and a method of manufacturing the same.
- FIGS. 1A to 1D schematically show typical structures of main parts of the magnetic memory element 70 according to the present embodiment.
- 1A is a perspective view thereof
- FIG. 1B is an xz sectional view
- 1C and 1D are xy plan views of the first magnetization free layer 10 included in the magnetic memory element 70.
- the magnetic memory element 70 includes at least a first magnetization free layer 10, a nonmagnetic layer 30, a reference layer 40, and a magnetization fixed layer 60.
- the first magnetization free layer 10, the reference layer 40, and the magnetization fixed layer 60 are made of a ferromagnetic material.
- FIG. 1B and FIG. 1C examples of the magnetization directions of the respective magnetic layers are indicated by arrows.
- FIG. 1C is a plan view schematically showing the structure of the first magnetization free layer 10.
- the first magnetization free layer 10 is made of a ferromagnetic material having perpendicular magnetic anisotropy.
- the first magnetization free layer 10 is composed of three regions: a first magnetization fixed region 11a, a second magnetization fixed region 11b, and a magnetization free region 12.
- the first magnetization fixed region 11a and the second magnetization fixed region 11b have magnetization substantially fixed in one direction.
- the magnetizations of the first magnetization fixed region 11a and the second magnetization fixed region 11b are fixed in antiparallel directions.
- FIG. 1C is a plan view schematically showing the structure of the first magnetization free layer 10.
- the first magnetization free layer 10 is made of a ferromagnetic material having perpendicular magnetic anisotropy.
- the first magnetization free layer 10 is composed of three regions: a first magnetization fixed region 11a, a second magnetization fixed region 11b, and a magnetization
- the first magnetization free region 11a and the second magnetization fixed region 11b are depicted as being fixed in the + z direction and the ⁇ z direction, respectively.
- the magnetization of the magnetization free region 12 can be reversed. In this case + z, it can be oriented either in the direction of -z.
- the boundary between the first magnetization fixed region 11a and the magnetization free region 12 and the second according to the magnetization direction of the magnetization free region 12 and the second A domain wall is formed at one of the boundaries between the magnetization fixed region 11 b and the magnetization free region 12.
- FIG. 1C when the magnetization of the magnetization free region 12 is in the + z direction, a domain wall is formed at the boundary between the second magnetization fixed region 11b and the magnetization free region 12, and when the magnetization of the magnetization free region 12 is in the ⁇ z direction, A domain wall is formed at the boundary between the one magnetization fixed region 11 a and the magnetization free region 12.
- the first magnetization fixed region 11a is adjacent to one end of the magnetization free region 12, and the second magnetization fixed region 11b is another end of the magnetization free region 12. Adjacent to. Specifically, in the example of FIG. 1C, the first magnetization fixed region 11a is adjacent to the ⁇ x direction side end of the magnetization free region 12, and the second magnetization fixed region 11b is on the + x direction side of the magnetization free region 12. Adjacent to the edge.
- the first magnetization fixed region 11a and the second magnetization fixed region 11b may be connected to the magnetization free region 12, and the positional relationship between them is arbitrary.
- the first magnetization fixed region 11 a may be connected to one end of the magnetization free region 12, and the second magnetization fixed region 11 b may be connected to the one end of the magnetization free region 12.
- Magnetization free layer 10 in this case is a structure having a three-way intersection.
- the first magnetization free layer 10, the nonmagnetic layer 30, and the reference layer 40 are provided in this order.
- the reference layer 40 is made of a ferromagnetic material.
- the nonmagnetic layer 30 is made of a nonmagnetic material, and preferably made of an insulator.
- the magnetic tunnel junction Magnetic Tunnel Junction; MTJ
- MTJ Magnetic Tunnel Junction
- the nonmagnetic layer 30 and the reference layer 40 connected to the first magnetization free layer 10 via the nonmagnetic layer 30 are connected to the magnetization free region 12 of the first magnetization free layer 10.
- the shapes of the nonmagnetic layer 30 and the reference layer 40 are arbitrary.
- the reference layer 40 is preferably made of a ferromagnetic material having perpendicular magnetic anisotropy and has a magnetization substantially fixed in one direction.
- the magnetization of the reference layer 40 is fixed in the + z direction.
- the reference layer 40 may have the following laminated structure.
- the reference layer 40 may have a structure in which three layers of a ferromagnetic material, a nonmagnetic material, and a ferromagnetic material are laminated in this order.
- the non-magnetic material sandwiched between the two ferromagnetic materials has a function of magnetically coupling the upper and lower ferromagnetic materials in an antiparallel direction (laminated ferri-coupling).
- Ru ruthenium
- Ru is known as a nonmagnetic material having such a function.
- an antiferromagnetic material may be adjacent to the reference layer. This is because the magnetization direction of the interface can be fixed in one direction by adjoining antiferromagnetic materials and performing heat treatment in a magnetic field.
- Typical antiferromagnetic materials include Pt—Mn and Ir—Mn.
- the magnetization fixed layer 60 has at least a first magnetization fixed layer 60a.
- the magnetization fixed layer 60 includes a first magnetization fixed layer 60a and a second magnetization fixed layer 60b.
- the first magnetization fixed layer 60a is provided magnetically connected to the first magnetization fixed region 11a.
- the second magnetization fixed layer 60b is provided magnetically connected to the second magnetization fixed region 11b.
- the term “magnetically connected” as used herein means that magnetic interaction occurs, and it is not necessary to be adjacent to each other, and it is not necessary to be electrically connected.
- the magnetization pinned layer 60 has a role of fixing the magnetization directions of the first magnetization pinned region 11a and the second magnetization pinned region 11b in the antiparallel direction as described above and then pinning them in that direction. Therefore, in the example shown in FIGS. 1A to 1D, a region of the first magnetization free layer 10 that overlaps the first magnetization fixed layer 60a becomes the first magnetization fixed region 11a, and overlaps with the second magnetization fixed layer 60b. The wrapping region becomes the second magnetization fixed region 11b, and the other region becomes the magnetization free region 12.
- the boundary line between the first magnetization fixed region 11a and the magnetization free region 12 is defined as a first boundary line B1
- the boundary line between the second magnetization fixed region 11b and the magnetization free region 12 is defined as a second boundary line B2. Therefore, the first boundary line B1 is defined by a curve that crosses the first magnetization free layer 10 in the xy plane among the outer peripheral lines of the first magnetization fixed layer 60a.
- the second boundary line B2 is defined by a curve that crosses the first magnetization free layer 10 in the xy plane among the outer peripheral lines of the second magnetization fixed layer 60b.
- the feature of this embodiment is the form of the first boundary line B1 and the second boundary line B2.
- the requirement will be described with reference to FIG. 1D.
- the centers in the xy plane of the first magnetization fixed region 11a, the second magnetization fixed region 11b, and the magnetization free region 12 are defined as a point P11a, a point P11b, and a point P12.
- a line segment connecting the points P11a and P12 is defined as a first line segment S1
- a line segment connecting the points P11b and P12 is defined as a second line segment S2.
- a straight line that is a perpendicular line of the first line segment S1 and that is in contact with the first boundary line B1 is a first perpendicular line N1
- a straight line that is a perpendicular line of the second line segment S2 and is in contact with the second boundary line B2 is a second perpendicular line.
- N2 is defined.
- at least the first boundary line B1 has a first displacement D1 with respect to the first line segment N1.
- the magnetization fixed layer 60 includes the first magnetization fixed layer 60a and the second magnetization fixed layer 60b as shown in FIGS. 1A to 1D
- the first boundary line B1 is relative to the first line segment N1.
- the first displacement D1 and the second boundary line B2 preferably have the second displacement D2 with respect to the second line segment N2.
- the magnitudes of the first displacement D1 and the second displacement D2 are approximately the same as or larger than the domain wall width of the domain wall formed in the first magnetization free layer 10.
- the domain wall width is an amount determined by the magnetic anisotropy constant Ku and the exchange stiffness constant A of the ferromagnetic material used for the first magnetization free layer 10.
- the domain wall width is about 5 to 20 nm. Therefore, it can be said that the first displacement D1 and the second displacement D2 are preferably 5 nm or more.
- the first magnetization fixed region 11a and the second magnetization fixed region 11b are connected to different external wirings, and the reference layer 40 is connected to another external wiring. That is, the magnetic memory element 70 is a three-terminal element. It should be noted that other layers may be inserted into the first magnetization fixed region 11a, the second magnetization fixed region 11b and the external wiring path, and the reference layer 40 and the external wiring path.
- the first magnetization fixed region 11a and the first magnetization fixed layer 60a are electrically connected, and the first magnetization fixed layer 60a is connected to an external wiring, while the second magnetization fixed region 11b and the second magnetization fixed layer 60b. May be electrically connected, and the second magnetization fixed layer 60b may be connected to a different external wiring.
- FIG. 2A and 2B schematically show examples of magnetization states in the memory states of “0” and “1” of the magnetic memory element 70 according to the present embodiment.
- 2A shows the magnetization state in the “0” state
- FIG. 2B shows the magnetization state in the “1” state.
- the magnetization of the first magnetization fixed region 11a is fixed in the + z direction
- the magnetization of the second magnetization fixed region 11b is fixed in the ⁇ z direction.
- the magnetization of the magnetization free region 12 has a + z direction component.
- the domain wall DW is formed at the boundary with the second magnetization fixed region 11b.
- the magnetization of the magnetization free region 12 has a ⁇ z direction component.
- the domain wall DW is formed at the boundary with the first magnetization fixed region 11a.
- the magnetization of the reference layer 40 is depicted as being fixed in the + z direction.
- the magnetization arrangement of the MTJ formed from the first magnetization free layer 10, the nonmagnetic layer 30, and the reference layer 40 is They are parallel and antiparallel respectively. Therefore, when a current is passed through the MTJ, a low resistance and a high resistance are realized.
- the correspondence between the magnetization state and the memory state (“0”, “1”) defined in FIGS. 2A and 2B is arbitrary and is not limited to this.
- the initialization refers to introducing a single domain wall in the first magnetization free layer 10 so that the magnetizations of the first magnetization fixed region 11a and the second magnetization fixed region 11b are in antiparallel directions to each other. It means a process.
- 3A to 3C schematically show an example of a method for initializing the memory state of the magnetic memory element 70 according to the present embodiment.
- layers other than the first magnetization free layer 10 and the magnetization fixed layer 60 are omitted for the sake of simplicity.
- the magnetization fixed layer 60 includes a first magnetization fixed layer 60a and a second magnetization fixed layer 60b.
- the first magnetization fixed layer 60a is harder than the second magnetization fixed layer 60b.
- the memory state is initialized by applying an external magnetic field in the following steps.
- a sufficiently large external magnetic field is applied in the + z direction.
- the magnetization of the entire region faces the + z direction.
- a relatively small external magnetic field is applied in the ⁇ z direction.
- the magnetization of the magnetization free region 12 first reverses and faces the ⁇ z direction.
- the external magnetic field in the ⁇ z direction is slightly strengthened.
- the second magnetization fixed region 11b and the second magnetization fixed layer 60b are reversed and face the ⁇ z direction.
- the state shown in FIG. 3C is a state where the domain wall is trapped at the boundary between the first magnetization fixed region 11a and the magnetization free region 12, that is, the step S1, which corresponds to the “1” state in FIG. 2B.
- the memory state of the magnetic memory element 70 can be initialized.
- FIG. 4A and 4B schematically show a method of writing information to the magnetic memory element 70 according to the present embodiment.
- 4A and 4B illustration of layers other than the first magnetization free layer 10 is omitted for simplicity.
- a current is introduced in the direction indicated by the arrow Iwrite in FIG. 4A.
- conduction electrons flow from the second magnetization fixed region 11 b to the first magnetization fixed region 11 a via the magnetization free region 12 in the first magnetization free layer 10.
- a spin transfer torque acts on the domain wall DW formed at the boundary between the second magnetization fixed region 11b and the magnetization free region 12, and moves in the negative direction of the x axis. That is, current-induced domain wall movement occurs.
- the domain wall DW stops at the boundary between the first magnetization fixed region 11a and the magnetization free region 12. to. This state corresponds to the “1” state defined in FIG. 2B. In this way, “1” writing can be performed.
- FIGS. 1A to 1D schematically show a method of reading information from the magnetic memory element having the configuration shown in FIGS. 1A to 1D.
- the magnetization fixed layer 60 is not shown.
- information is read mainly using the tunneling magnetoresistive effect (TMR effect).
- TMR effect tunneling magnetoresistive effect
- MTJ magnetic tunnel junction
- FIG. 5A when Iread is introduced in the “0” state defined in FIG. 2A, the magnetization is in a parallel state in the MTJ, so a low resistance is realized.
- FIG. 5B when Iread is introduced in the “1” state defined in FIG. 2B, the magnetization is antiparallel in the MTJ, so that high resistance is realized. In this way, information stored in the magnetic memory element can be detected as a difference in resistance value.
- Circuit configuration Next, a circuit configuration for introducing a write current and a read current into the magnetic memory cell 80 having the magnetic memory element 70 according to the present embodiment will be described.
- FIG. 6 shows a configuration example of a circuit for one bit of the magnetic memory cell 80.
- the magnetic memory element 70 is a three-terminal element, and is connected to the word line WL, the ground line GL, and the bit line pair BLa, BLb.
- the terminal connected to the reference layer 40 is connected to the ground line GL for reading.
- a terminal connected to the first magnetization fixed region 11a is connected to one of the source / drain of the transistor TRa, and the other of the source / drain is connected to the bit line BLa.
- a terminal connected to the second magnetization fixed region 11b is connected to one of the source / drain of the transistor TRb, and the other of the source / drain is connected to the bit line BLb.
- Transistor TRa the gate of TRb is connected to a common word line WL.
- the first magnetization fixed region 11a is connected to the transistor TRa via the first magnetization fixed layer 60a
- the second magnetization fixed region 11b is connected to the transistor TRb via the second magnetization fixed layer 60b.
- An example is shown.
- the word line WL is set to the high level, and the transistors TRa and TRb are turned on.
- one of the bit line pair BLa and BLb is set to a high level, and the other is set to a low level (ground level).
- a write current flows between the bit line BLa and the bit line BLb via the transistors TRa and TRb and the first magnetization free layer 10.
- the word line WL is set to a high level, and the transistors TRa and TRb are turned on. Further, the bit line BLa is set to an open state, and the bit line BLb is set to a high level. As a result, the read current flows from the bit line BLb through the transistor TRb and the MTJ of the magnetic memory element 70 to the ground line GL. This enables reading using the magnetoresistive effect.
- FIG. 7 is a block diagram showing an example of the configuration of the magnetic memory 90 according to an example of the present embodiment.
- the magnetic memory 90 includes a memory cell array 110, an X driver 120, a Y driver 130, and a controller 140.
- the memory cell array 110 has a plurality of magnetic memory cells 80 arranged in an array.
- Each of the magnetic memory cells 80 has the magnetic memory element 70 described above.
- each magnetic memory cell 80 is connected to the word line WL, the ground line GL, and the bit line pair BLa, BLb.
- the X driver 120 is connected to a plurality of word lines WL, and drives a selected word line connected to the accessed magnetic memory cell 80 among the plurality of word lines WL.
- the Y driver 130 is connected to a plurality of bit line pairs BLa and BLb, and sets each bit line to a state corresponding to data writing or data reading.
- the controller 140 controls each of the X driver 120 and the Y driver 130 in accordance with data writing or data reading.
- FIGS. 8A to 8H are sectional views schematically showing an example of a process for manufacturing the magnetic memory element 70 shown in FIGS. 1A to 1D.
- a layer to be the first magnetization fixed layer 60a is deposited on the substrate in which the electrode is embedded (the electrode is omitted in the drawing). This state corresponds to FIG. 8A.
- the first magnetization fixed layer 60a is patterned. This state corresponds to FIG. 8B.
- a layer to be the second magnetization fixed layer 60b is deposited. This state corresponds to FIG. 8C.
- the second magnetization fixed layer 60b is patterned. This state corresponds to FIG. 8D.
- the manufacturing method described here is an example of a method of forming the magnetic memory element 70, and can be formed by using other methods.
- B2 is characterized by having a first displacement D1 and a second displacement D2 with respect to the first perpendicular line N1 and the second perpendicular line N2, respectively.
- Such displacement can be formed, for example, as follows.
- the above-described displacement occurs in the first magnetization fixed layer 60a and the second magnetization fixed layer 60a. it can be formed by controlling the shape of the magnetization fixed layer 60b.
- the above-described displacement can be formed by performing photolithography using a photomask as shown in FIG.
- the first magnetization fixed layer pattern L60a for forming the first magnetization fixed layer 60a and the second magnetization are compared with the first magnetization free layer pattern L10 for forming the first magnetization free layer 10.
- the second magnetization fixed layer pattern L60b for forming the fixed layer 60b is designed to be large by a margin M in the y direction.
- the same degree of blur as the wavelength ⁇ of the laser used in photolithography occurs, and the first magnetization fixed layer pattern L60a and the second magnetization fixed layer pattern L60b drawn by solid lines are actually formed.
- the 1st magnetization fixed layer 60a and the 2nd magnetization fixed layer 60b become the shape where the angle fell, as each shown with the broken line.
- the first boundary line B1 and the second boundary line B2 having the above displacement can be formed.
- the margin M in FIG. 9 is preferably equal to or greater than the wavelength ⁇ of the laser used in photolithography. Further, the shape with the corner as shown by the broken line in FIG. 9 can be adjusted by shifting the focus at the time of photolithography from the just focus.
- the first magnetization free layer 10 is preferably made of a ferromagnetic material having perpendicular magnetic anisotropy.
- alloy materials such as Fe alloy, Gd—Co alloy, Co—Cr—Pt alloy, Co—Re—Pt alloy, Co—Ru—Pt alloy, Co—W alloy, Co / Pt multilayer film, Co / Pd Alternating laminated films such as laminated films, Co / Ni laminated films, Co / Cu laminated films, Co / Ag laminated films, Co / Au laminated films, Fe / Pt laminated films, Fe / Pd laminated films, Fe / Pd laminated films, Fe / Au laminated films, etc.
- Non-Patent Document 4 A film is mentioned as a suitable material for the first magnetization free layer 10.
- the nonmagnetic layer 30 is preferably made of an insulating material. Specifically, Mg—O, Al—O, Al—N, Ti—O and the like are exemplified.
- the reference layer 40 is made of a ferromagnetic material having perpendicular magnetic anisotropy, for example. At this time, materials that can be used for the reference layer 40 are omitted because they overlap with those exemplified as materials that can be used for the first magnetization free layer 10. However, since the reference layer 40 is required to have stable and fixed magnetization, it is preferable that the reference layer 40 be a magnetic material as hard as possible.
- an Fe—Pt alloy, an Fe—Pd alloy, a Co—Pt alloy, a Co / Pt laminated film, a Co / Pd laminated film, and the like are preferable.
- the magnetization direction needs to be fixed in one direction, and the leakage magnetic field to the outside is preferably small. Therefore, as described above, it is preferable to have a laminated structure having laminated ferribonds. That is, it is preferable that the reference layer 40 has a laminated structure such as ferromagnetic material / Ru / ferromagnetic material.
- the reference layer 40 may be composed of a ferromagnetic material having in-plane magnetic anisotropy. In this case, any magnetic material can be used. A typical example is Co—Fe. An example of an embodiment in which a material having in-plane magnetic anisotropy is used for the reference layer will be described later as a fourth modification.
- the magnetization fixed layer 60 is made of a ferromagnetic material having perpendicular magnetic anisotropy.
- FIG. 10 shows the calculation result of the leakage magnetic field from the magnetization fixed layer 60 at the position (line segment AB) of the first magnetization free layer 10 in the structure including the first magnetization free layer 10 and the magnetization fixed layer 60.
- the material of the magnetization fixed layer 60 is a Co—Pt alloy having a thickness of 10 nm.
- a leakage magnetic field (Hz) of about 1000 Oe is generated in the + z direction and the ⁇ z direction on the first magnetization fixed layer 60a and the second magnetization fixed layer 60b, respectively.
- the inventors of the present invention paid attention to the distribution in the x direction of the magnetic field (Hx) in the x direction in the vicinity of the first boundary line B1 and the second boundary line B2 and the structure of the domain wall to be formed.
- the leakage magnetic field (Hx) in the x-direction has a very sharp peak in the vicinity of the first boundary line B1 and the second boundary line B2, and the magnitude is about 10 minutes when separated by 10 nm. It turns out that it has become small to about 1 of. Therefore, it can be seen that if the position where the domain wall is formed is about 10 nm away from the Hx peak position, it can be depinned by the current almost without being affected by the leakage magnetic field.
- the structure of the domain wall formed when the first boundary line B1 and the second boundary line B2 have displacement is shown by a bold line in FIG. 11A. It is advantageous in terms of exchange energy that the domain wall is formed so that its area is as small as possible. Therefore, when the domain wall is formed in the vicinity of the first boundary line B1 as shown in FIG. 11A, the first boundary line B1 is completely formed. It is not formed along. At this time, a part of the domain wall exists at a location away from the first boundary line B1. That is, a gap is formed between a part of the domain wall DW and the first boundary line B1. In the example of FIG. 11A, such a region is formed at both end portions (end portions in the ⁇ y direction) of the first magnetization free layer 10.
- the present embodiment is particularly effective when the saturation magnetization (Ms) of the ferromagnetic material used as the magnetization fixed layer 60 is large or when the film thickness (t) is large. Therefore, for example, when only the first magnetization fixed layer 60a has a large saturation magnetization (Ms) or a film thickness (t) out of the first magnetization fixed layer 60a and the second magnetization fixed layer 60b, the first boundary line B1 It is understood that only the first perpendicular line N1 may be formed to have the first displacement D1, and the second boundary line B2 may be formed to overlap the second perpendicular line N2.
- (First modification) 12A to 12C schematically show the structure of a first modification of the magnetic memory element 70 according to this embodiment.
- the first modification relates to the form of the first boundary line B1 and the second boundary line B2.
- first boundary line B1 and the second boundary line B2 have a first displacement D1 and a second displacement D2 with respect to the first perpendicular line N1 and the second perpendicular line N2, respectively.
- first boundary line B1 and the second boundary line B2 curves that protrude inward are illustrated in the drawings so far (for example, FIGS. 1A, 1C, and 1D).
- the form of the first boundary line B1 and the second boundary line B2 is arbitrary.
- Figure 12A ⁇ FIG 12C is the x-y plane view showing a specific example.
- first boundary line B1 and the second boundary line B2 may be formed to be convex outward as shown in FIG. 12A.
- first perpendicular line N1 and the second perpendicular line N2 (not shown) may be formed obliquely.
- it may be formed to have irregularities.
- the structure of the domain wall DW predicted to be formed in the vicinity of the first boundary line B1 is indicated by a bold line in the drawing. In either case, a gap is formed between the first boundary line B1 and depinning at a low current becomes possible as described with reference to FIGS. 11A to 11C.
- (Second modification) 13A and 13B schematically show the structure of a second modification of the magnetic memory element 70 according to this embodiment.
- the second modification relates to the position of the magnetization fixed layer 60.
- the magnetization fixed layer 60 is provided in order to fix the magnetizations of the first magnetization fixed region 11a and the second magnetization fixed region 11b in an antiparallel direction.
- the magnetization fixed layer 60 is illustrated as being formed on the substrate side ( ⁇ z direction) with respect to the first magnetization free layer 10, but this position is arbitrary.
- FIG. 13A and FIG. 13B show one modification regarding the arbitraryness of the position of the magnetization fixed layer 60.
- the magnetization fixed layer 60 is disposed on the opposite side (+ z direction) to the first magnetization free layer 10 from the substrate. More specifically, the first magnetization fixed layer 60a is provided above the first magnetization fixed region 11a, and the second magnetization fixed layer 60b is provided above the second magnetization fixed region 11b. As described above, in the present embodiment, it is only necessary to satisfy the above-described requirements with respect to the first boundary B1 and the first perpendicular line N1, and the position of the magnetization fixed layer 60 is arbitrary.
- FIG. 15A schematically show the structure of a third modification of the magnetic memory element 70 according to the present embodiment.
- the third modification relates to the number of the magnetization fixed layers 60.
- the magnetization fixed layer 60 is provided in order to fix the magnetizations of the first magnetization fixed region 11a and the second magnetization fixed region 11b in an antiparallel direction.
- the magnetization fixed layer 60 includes two layers, a first magnetization fixed layer 60a and a second magnetization fixed layer 60b.
- the first magnetization fixed layer 60a is magnetically connected to the first magnetization fixed layer 11a.
- An example has been shown in which the second magnetization fixed layer 60b is magnetically connected to the second magnetization fixed region 11b.
- the number of the magnetization fixed layers 60 is arbitrary. 14A to 14C, FIG. 15A, and FIG. 15B show modified examples related to the arbitraryness of the number of the magnetization fixed layers 60.
- FIG. 14A to 14C, FIG. 15A, and FIG. 15B show modified examples related to the arbitraryness of the number of the magnetization fixed layers 60.
- the magnetization fixed layer 60 includes only the first magnetization fixed layer 60a magnetically connected to the first magnetization fixed region 11a, and the first magnetization fixed layer 60a is formed on the first magnetization fixed region 11a.
- the conductive layer 50 is connected to the lower side of the second magnetization fixed region 11b.
- the conductive layer 50 is made of a nonmagnetic metal.
- the second boundary line B ⁇ b> 2 is defined by a curve crossing the first magnetization free layer 10 among the outer peripheral lines of the conductive layer 50.
- the second boundary line B2 is a second displacement D2 (FIGS. 14A to 14C) with respect to the second perpendicular line N2 (not shown in FIGS. 14A to 14C). (Not shown) need not be formed.
- the magnetization fixed layer 60 includes only the first magnetization fixed layer 60a magnetically connected to the first magnetization fixed region 11a, and the first magnetization fixed layer 60a. Is magnetically connected to the upper side with respect to the first magnetization free region 11a.
- the first magnetization fixed region 11a and the second magnetization fixed region 11b are adjacent to the conductive layer 50 on the lower surface in order to be connected to the lower wiring and the transistor. Even in such a structure, the present invention can be implemented.
- (Fourth modification) 16A to 16D schematically show the structure of a fourth modification of the magnetic memory element 70 according to this embodiment.
- the fourth modification relates to a reading method.
- the nonmagnetic layer 30 and the reference layer 40 are provided to read information from the first magnetization free layer 10 which is an information storage layer.
- the fourth modification relates to another reading mode.
- the second magnetization free layer 20 is newly provided. Further, a contact layer 25 is preferably provided. In addition, the second magnetization free layer 20, the nonmagnetic layer 30, and the reference layer 40 are provided adjacent to each other in this order, thereby forming a magnetic tunnel junction (MTJ).
- the centroid (geometric centroid) of the second magnetization free layer 20 is provided so as to be shifted in the xy plane with respect to the centroid of the magnetization free region 12 of the first magnetization free layer 10. Now, the direction of this shift is defined as the first direction.
- the second magnetization free layer 20 and the reference layer 40 are made of a ferromagnetic material having magnetic anisotropy in the in-plane direction.
- the direction of magnetic anisotropy of the second magnetization free layer 20 is arbitrary in the in-plane direction.
- the magnetization of the reference layer 40 is substantially fixed in one direction. This direction is preferably parallel to the first direction.
- 13A and 13B show an example in which the first direction is the y direction, that is, the direction perpendicular to the longitudinal direction of the first magnetization free layer 10.
- the first direction is optional, and may be, for example, the x direction.
- the information stored in the magnetization direction in the perpendicular direction of the magnetization free region 12 is stored in the MTJ having in-plane magnetization composed of the second magnetization free layer 20, the nonmagnetic layer 30, and the reference layer 40.
- the magnetization of the second magnetization free layer 20 is directed in the y-axis positive direction by the leakage magnetic flux generated by the upward magnetization of the magnetization free region 12.
- the second magnetization free layer 20 is arranged above the magnetization free region 12 (in the positive z-axis direction), and the center of gravity of the second magnetization free layer 20 is in the positive y-axis direction with respect to the magnetization free region 12. This is because they are shifted. As a result, the magnetizations of the second magnetization free layer 20 and the reference layer 40 become parallel, and this MTJ is in a low resistance state.
- the magnetization of the second magnetization free layer 20 is directed in the y-axis negative direction by the leakage magnetic flux generated by the magnetization in the downward direction of the magnetization free region 12.
- the magnetizations of the second magnetization free layer 20 and the reference layer 40 become antiparallel, and this MTJ enters a high resistance state.
- the information stored as the magnetization in the perpendicular direction of the magnetization free region 12 is transmitted to the magnetization of the second magnetization free layer 20 having the in-plane magnetization, and can be read out by the MTJ composed of the in-plane magnetization.
- MR ratio magnetoresistive effect ratio
- the second magnetization free layer 20 and the reference layer 40 are made of a material having in-plane magnetic anisotropy. Specifically, Co—Fe—B and the like are exemplified.
- the nonmagnetic layer 30 is preferably composed of a nonmagnetic material. Specifically, Mg—O and the like are exemplified.
- Examples of utilization of the present invention include nonvolatile semiconductor memory devices used in mobile phones, mobile personal computers and PDAs, and microcomputers with built-in nonvolatile memory used in automobiles and the like. It can also be used for large-scale storage devices such as racetrack memory.
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Abstract
Description
次に本実施形態に係る磁気メモリ素子のメモリ状態について説明する。
図2A、図2Bは本実施形態に係る磁気メモリ素子70の“0”、“1”それぞれのメモリ状態における磁化の状態の例を模式的に示している。図2Aは“0”状態における磁化の状態を、図2Bは“1”状態における磁化の状態を示している。なおここでは第1磁化固定領域11aの磁化は+z方向に固定され、第2磁化固定領域11bの磁化は-z方向に固定されているものとしている。
次に本実施形態に係る磁気メモリ素子70のメモリ状態の初期化方法について説明する。なお、ここで言う初期化とは、第1磁化固定領域11aと第2磁化固定領域11bの磁化を互いに反平行方向になるように向け、第1磁化自由層10に単一の磁壁を導入するプロセスのことを意味する。
次に本実施形態に係る磁気メモリ素子70への情報の書き込み方法について説明する。図4A、図4Bは本実施形態に係る磁気メモリ素子70への情報の書き込み方法を模式的に示している。なお、図4A、図4Bでは簡単のために第1磁化自由層10以外の層の図示は省略されている。いま、図2Aで定義された“0”状態において図4Aに矢印Iwriteで示された方向に電流を導入する。このとき伝導電子は第1磁化自由層10において第2磁化固定領域11bから磁化自由領域12を経由して第1磁化固定領域11aへと流れる。このとき第2磁化固定領域11bと磁化自由領域12の境界に形成された磁壁DWにはスピントランスファートルク(Spin Transfer Torque;STT)が働き、x軸の負方向に移動する。すなわち電流誘起磁壁移動が起こる。ここで、書き込み電流は第1磁化固定領域11aと磁化自由領域12の境界よりもx軸の負の方向では減少するため、磁壁DWは第1磁化固定領域11aと磁化自由領域12の境界で停止する。この状態は図2Bで定義された“1”状態に相当する。このようにして“1”書き込みを行うことができる。
次に本実施形態に係る磁気メモリ素子からの情報の読み出し方法について説明する。図5A、図5Bは図1A~図1Dに示された構成を有する磁気メモリ素子からの情報の読み出し方法を模式的に示している。これらの図において、磁化固定層60の図示は省略されている。本実施形態においては主にトンネル磁気抵抗効果(Tunneling Magnetoresistive effect;TMR effect)を利用して情報の読み出しを行う。そのために第1磁化自由層10、非磁性層30、リファレンス層40から構成される磁気トンネル接合(MTJ)を貫通する方向に電流Ireadを導入する。なおこのIreadの方向には任意性がある。
次に、本実施形態に係る磁気メモリ素子70を有する磁気メモリセル80に書き込み電流及び読み出し電流を導入するための回路構成について説明する。
次に、本実施形態に係る磁気メモリ素子70の製造方法について図8A~図8H、図9を用いて説明する。
次に第1磁化自由層10、非磁性層30、リファレンス層40、及び磁化固定層50に用いることのできる材料について説明する。
第1磁化自由層10は前述の通り垂直磁気異方性を有する強磁性体により構成されることが好ましい。具体的にはFe-Pt合金、Fe-Pd合金、Co-Pt合金、Co-Pd合金、Tb-Fe-Co合金、Gd-Fe-Co合金、Tb-Fe合金、Tb-Co合金、Gd-Fe合金、Gd-Co合金、Co-Cr-Pt合金、Co-Re-Pt合金、Co-Ru-Pt合金、Co-W合金などの合金系材料のほか、Co/Pt積層膜、Co/Pd積層膜、Co/Ni積層膜、Co/Cu積層膜、Co/Ag積層膜、Co/Au積層膜、Fe/Pt積層膜、Fe/Pd積層膜、Fe/Au積層膜などの交互積層膜が例示される。特にこの中で発明者らはCo/Ni積層膜を用いて制御性の高い電流誘起磁壁移動が実現できることを実験的に確認しており(非特許文献4参照)、この点でCo/Ni積層膜が第1磁化自由層10の好適な材料として挙げられる。
次に本実施形態で得られる効果について説明する。本実施形態によって垂直磁化磁壁移動MRAMにおける書き込み電流の低減がもたらされる。その原理を以下に説明する。
以上で説明された磁気メモリ素子70は以下に説明される変形例を用いても実施することができる。
図12A~図12Cは本実施形態に係る磁気メモリ素子70の第1の変形例の構造を模式的に示している。第1の変形例は第1境界線B1、及び第2境界線B2の形態に関する。
図13A、図13Bは本実施形態に係る磁気メモリ素子70の第2の変形例の構造を模式的に示している。第2の変形例は磁化固定層60の位置に関する。
図14A~図14C、図15A、図15Bは本実施形態に係る磁気メモリ素子70の第3の変形例の構造を模式的に示している。第3の変形例は磁化固定層60の数に関する。
図16A~図16Dは本実施形態に係る磁気メモリ素子70の第4の変形例の構造を模式的に示している。第4の変形例は読み出し方法に関する。
本発明の活用例として、携帯電話、モバイルパソコンやPDAに使用される不揮発性の半導体メモリ装置や、自動車などに使用される不揮発性メモリ内蔵のマイコンが挙げられる。またレーストラックメモリのような大規模のストレージデバイスなどへの活用も可能である。
Claims (8)
- 第1磁化自由層と、非磁性層と、リファレンス層と、磁化固定層を具備し、
前記第1磁化自由層は垂直磁気異方性を有する強磁性体から構成され、
前記第1磁化自由層は第1磁化固定領域と第2磁化固定領域と磁化自由領域から構成され、
前記磁化固定層は、前記第1磁化固定領域に磁気的に接続された第1磁化固定層を少なくとも具備し、
前記第1磁化固定層の外周線のうち第1磁化自由層を横断する曲線部を第1境界線とし、前記磁化自由領域と前記第1磁化固定領域の中心を結ぶ線分を第1線分とし、前記第1線分の垂線であって、かつ第1境界線と接する線分を第1垂線としたとき、前記第1境界線と前記第1垂線の間に第1変位が存在する
磁気メモリ素子。 - 請求項1記載の磁気メモリ素子であって、
前記磁化固定層はさらに前記第2磁化固定領域に磁気的に接続された第2磁化固定層を具備し、
前記第2磁化固定層の外周線のうち第1磁化自由層を横断する曲線部を第2境界線とし、前記磁化自由領域と前記第2磁化固定領域の中心を結ぶ線分を第2線分とし、前記第2線分の垂線であって、かつ第2境界線と接するような線分を第2垂線としたとき、前記第2境界線と前記第2垂線の間に第2変位が存在する
磁気メモリ素子。 - 請求項1または請求項2に記載の磁気メモリ素子であって、
前記第1変位と前記第2変位のうちの少なくとも一方が5nm以上である
磁気メモリ素子。 - 請求項1乃至3のいずれかに記載の磁気メモリ素子であって、
前記第1境界線と前記第2境界線のうちの少なくとも一方が基板平行平面内において凹、凸、凹凸のいずれかを有している
磁気メモリ素子。 - 請求項1乃至3のいずれかに記載の磁気メモリ素子であって、
前記第1境界線と前記第2境界線のうちの少なくとも一方が、それぞれ前記第1垂線、前記第2垂線に対して斜めに交わる
磁気メモリ素子。 - 請求項1乃至5のいずれかに記載の磁気メモリ素子であって、
前記非磁性層は、前記磁化自由領域に隣接して設けられ、
前記リファレンス層は、前記非磁性層に隣接して前記磁化自由領域とは反対側に設けられ、
前記リファレンス層は垂直磁気異方性を有する強磁性体により構成される
磁気メモリ素子。 - 請求項1乃至5のいずれかに記載の磁気メモリ素子であって、
さらに第2磁化自由層が設けられ、
前記非磁性層は、前記第2磁化自由層に隣接して設けられ、
前記リファレンス層は、前記非磁性層に隣接して前記第2磁化自由層とは反対側に設けられ、
前記第2磁化自由層は基板平行平面内において前記磁化自由領域に対して第1方向にずれて設けられ、
前記第2磁化自由層、及び前記リファレンス層は面内磁気異方性を有する強磁性体により構成され、
前記リファレンス層は前記第1の方向に略平行方向に固定された磁化を有する
磁気メモリ素子。 - 請求項1乃至7のいずれかに記載された磁気メモリ素子を複数具備する磁気メモリ。
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- 2011-06-16 JP JP2012522553A patent/JPWO2012002156A1/ja not_active Withdrawn
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EP2665104A1 (en) * | 2012-05-18 | 2013-11-20 | Samsung Electronics Co., Ltd | Magnetoresistive elements and memory devices including the same |
US8836057B2 (en) | 2012-05-18 | 2014-09-16 | Samsung Electronics Co., Ltd. | Magnetoresistive elements having protrusion from free layer and memory devices including the same |
KR101909201B1 (ko) | 2012-05-18 | 2018-10-17 | 삼성전자 주식회사 | 자기저항요소 및 이를 포함하는 메모리소자 |
JP2014067810A (ja) * | 2012-09-25 | 2014-04-17 | Toshiba Corp | 磁気メモリ |
WO2015182071A1 (ja) * | 2014-05-27 | 2015-12-03 | 日本電気株式会社 | 磁性体素子とその初期化方法および半導体集積回路 |
JP2016164955A (ja) * | 2015-03-06 | 2016-09-08 | ルネサスエレクトロニクス株式会社 | 半導体装置およびその製造方法 |
JP2020021857A (ja) * | 2018-08-02 | 2020-02-06 | Tdk株式会社 | 磁壁移動型磁気記録素子及び磁気記録アレイ |
Also Published As
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US20130140660A1 (en) | 2013-06-06 |
US8791534B2 (en) | 2014-07-29 |
JPWO2012002156A1 (ja) | 2013-08-22 |
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