WO2007119446A1 - Mram、及びmramのデータ読み書き方法 - Google Patents
Mram、及びmramのデータ読み書き方法 Download PDFInfo
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- WO2007119446A1 WO2007119446A1 PCT/JP2007/055650 JP2007055650W WO2007119446A1 WO 2007119446 A1 WO2007119446 A1 WO 2007119446A1 JP 2007055650 W JP2007055650 W JP 2007055650W WO 2007119446 A1 WO2007119446 A1 WO 2007119446A1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B82—NANOTECHNOLOGY
- B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- B82Y10/00—Nanotechnology for information processing, storage or transmission, e.g. quantum computing or single electron logic
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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
-
- 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
-
- 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
- G11C11/1657—Word-line or row circuits
-
- 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
-
- 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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- 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
- 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
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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
Definitions
- the present invention relates to a magnetic random access memory (MRAM).
- MRAM magnetic random access memory
- the present invention relates to an MRAM based on a spin injection method and a data read / write method of the MRAM.
- MRAM is a promising nonvolatile memory from the viewpoint of high integration and high speed operation.
- a magnetoresistive element exhibiting a “magnetoresistance effect” such as a TMR (Tunnel MagnetoResistance) effect is used.
- TMR Tunnelnel MagnetoResistance
- MTJ magnetic tunnel junction
- the two ferromagnetic layers are composed of a pinned layer in which the direction of magnetization is fixed and a free layer force in which the direction of magnetization can be reversed.
- the MTJ resistance value (R + AR) when the direction of the magnetic layer of the pinned layer and the free layer is "antiparallel” is the resistance value when they are “parallel” due to the magnetoresistance effect ( It is known to be larger than R).
- the MRAM uses the magnetoresistive element having the MTJ as a memory cell, and stores data in a nonvolatile manner by utilizing the change in the resistance value. Data is written into the memory cell by reversing the direction of the magnetic layer in the free layer.
- the “asteroid method” and the “toggle method” are conventionally known. According to these write methods, the reversal magnetic field necessary for reversing the magnetic layer of the free layer becomes substantially inversely proportional to the memory cell size. That is, as the memory cell is miniaturized, the write current tends to increase.
- spin injection method has been proposed as a write method that can suppress an increase in write current due to miniaturization.
- the spin injection method is described in the following literature: Yagami and buzuki, Research. Trends in bpin Transfer Magnetization switching Research trends in spin-injection magnetization reversal), Journal of Japan Society of Applied Magnetics, Vol. 28, No. 9, 2004 o
- a spin-polarized current is applied to a ferromagnetic conductor. current
- spin Tran sfer Magnetization Switching The outline of spin transfer magnetization reversal will be explained with reference to FIG.
- the magnetoresistive element includes a free layer 101, a pinned layer 103, and a tunnel barrier layer 102 that is a nonmagnetic layer sandwiched between the free layer 101 and the pinned layer 103.
- the pinned layer 103 in which the orientation of the magnetic flux is fixed is formed to be thicker than the free layer 101, and plays a role as a mechanism (spin filter) for creating a spin-polarized current.
- the state in which the magnetic layer directions of the free layer 101 and the pinned layer 103 are parallel is associated with data “0”, and the state in which they are antiparallel is associated with data “1”.
- the spin transfer magnetization reversal shown in FIG. 1 is realized by a CPP (Current Perpendicular to Plane) method, and a write current is injected perpendicularly to the film surface. Specifically, when the data “0” force also changes to the data “1”, the current flows from the pinned layer 103 to the free layer 101. In this case, the electron force having the same spin state as the pinned layer 103 as a spin filter is free. The layer 101 force also moves to the pinned layer 103. Then, due to the spin transfer (spin angular momentum transfer) effect, the magnetic layer of the free layer 101 is reversed, while the transition from data “1” to data “0”.
- CPP Current Perpendicular to Plane
- the current flows from the free layer 101 to the pinned layer 103.
- the electron force having the same spin state as the pinned layer 103 as a spin filter moves from the pinned layer 103 force to the free layer 101.
- the magnetic layer of the free layer 101 is inverted due to the spin transfer effect.
- the direction of magnetization of the free layer 101 can be defined by the direction of the spin-polarized current injected perpendicular to the film surface.
- the threshold for writing depends on the current density. Therefore, as the memory cell size is reduced, the write current required for magnetization inversion decreases. Since the write current decreases with the miniaturization of memory cells, the spin transfer magnetization reversal is important for the realization of a large capacity of MRAM. It is important.
- Japanese Patent Application Laid-Open No. 2005-191032 discloses a domain wall motion type magnetic storage device.
- the magnetic storage device includes a magnetic pinned layer in which a magnetic pin is fixed, a tunnel insulating layer stacked on the magnetic fixed layer, and a magnetic free layer stacked on the tunnel insulating layer.
- the magnetization free layer has a junction overlapping the tunnel insulating layer and the magnetic pinned layer, a constricted portion adjacent to both ends of the joint, and a pair of magnetic pinned portions formed adjacent to the constricted portion.
- the pair of magnetic key fixing portions are provided with fixed magnetic keys in opposite directions.
- the magnetic storage device further includes a pair of magnetic information writing terminals electrically connected to the pair of magnetization fixed portions.
- the pair of magnetic information write terminals allows a write current to pass through the junction of the magnetization free layer, the pair of constricted portions, and the pair of magnetization fixed portions.
- the direction of the write current is controlled in accordance with the write data and is either the first direction or the second direction opposite to the first direction.
- the domain wall moves between the pair of constricted portions according to the direction of the write current.
- An object of the present invention is to provide a new MRAM using a spin injection method.
- Another object of the present invention is to provide a technique capable of simplifying a peripheral circuit for supplying a write current in an MRAM using a spin injection method.
- Still another object of the present invention is to provide an MRAM and a data writing method capable of suppressing deterioration of a tunnel barrier layer in MTJ.
- Still another object of the present invention is to provide an MRAM and a data write method capable of reducing a write current as the memory cell size is reduced.
- an MRAM in a first aspect of the present invention, includes a magnetic recording layer that is a ferromagnetic layer and a pinned layer connected to the magnetic recording layer via a nonmagnetic layer.
- the magnetic recording layer has a magnetization switching region, a first magnetization fixed region, and a second magnetization fixed region.
- the magnetization switching region has reversible magnetization and overlaps the pinned layer. Both the first magnetic pinned region and the second magnetic pinned region are connected to the same end of the magnetization switching region.
- the first magnetic field fixed region and the second magnetic field fixed region each have a first fixed magnetic field and a second fixed magnetic field whose directions are fixed. 1st fixed magnetization and 2nd One of the fixed magnetizations is fixed in a direction toward the one end, and the other is fixed in a direction away from the one end.
- the magnetization switching region, the first magnetic pinned region, and the second magnetic pinned region form a “three-way”.
- the magnetic recording layer is formed in a Y shape.
- the longitudinal direction of the magnetization switching region is the first direction
- the longitudinal direction of the first magnetization fixed region is the second direction
- the longitudinal direction of the second magnetization fixed region is the third direction.
- the angle formed by the first direction and the second direction is equal to the angle formed by the first direction and the third direction.
- the magnetic recording layer may have a mirror-symmetric shape with respect to an axis along the first direction.
- the magnetic recording layer includes a first side surface that spans the magnetization reversal region and the first magnetization fixed region, a second side surface that spans the magnetization reversal region and the second magnetic pinned region, the first magnetic pinned region, and the second magnetic field. And a third side extending over the fixed area of the magnet. At least one of the first side, second side, and third side may be smoothly formed! /.
- the magnetization switching region, the first magnetization fixed region, and the second magnetization fixed region described above are formed on the same plane.
- the MRAM according to the present invention may further include a pinning layer including at least one of a ferromagnetic material and an antiferromagnetic material.
- the pinning layer fixes the directions of the first fixed magnetic layer and the second fixed magnetic layer by either exchange coupling or magnetostatic coupling.
- the pinning layer is provided so as to overlap at least the first magnetic pinned region and the second magnetic pinned region.
- the magnetization direction of the pinning layer is the direction from the first magnetization fixed region to the second magnetization fixed region, or the second magnetic pinned region force is also directed to the first magnetic pinned region. is there.
- the pinning layer may include a first pinning layer for fixing the direction of the first fixed magnetic layer and a second pinning layer for fixing the direction of the second fixed magnetic layer.
- the first magnetization fixed region and the second magnetization fixed region have a magnetocrystalline anisotropy along a direction in which the first magnetic pinned region and the second magnetic pinned region are aligned. You may form so that it may have.
- the first magnetization fixed region force is directed toward the second magnetic domain fixed region, or the second magnetic domain fixed region force is directed toward the first magnetic domain fixed region. An external magnetic field is applied in the direction.
- the magnetic recording layer may include a plurality of magnetically coupled ferromagnetic layer covers. At least one of the plurality of ferromagnetic layers has the above-described magnetization switching region, the first magnetization fixed region, and the second magnetization fixed region.
- the MRAM according to the present invention includes a plurality of magnetic memory cells arranged in an array.
- Each of the plurality of magnetic memory cells includes the above-described magnetic recording layer and pinned layer.
- the plurality of magnetic memory cells include a first magnetic memory cell and a second magnetic memory cell arranged along the first axis.
- the shape of the magnetic recording layer of the first magnetic memory cell and the shape of the magnetic recording layer of the second magnetic memory cell may have a line-symmetric relationship with respect to the first axis.
- the first write current flows from the magnetic domain inversion region to the first magnetic field fixed region through the one end.
- the second write current flows from the magnetization switching region through the one end to the second magnetization fixed region.
- the first fixed magnet is fixed in the direction toward the one end described above, and the second fixed magnet is fixed in the direction away from the one end.
- the magnetization of the magnetization switching region is directed away from one end by the first write operation.
- the second write operation the magnetization of the magnetization switching region is directed in the direction toward one end thereof.
- the MRAM may further include an assist wiring formed so as to intersect the magnetic field inversion region.
- the direction of the magnetic field applied to the magnetization reversal region by the current flowing through the assist wiring is directed away from one end of the force.
- the second write operation the direction of the magnetic field applied to the magnetic field inversion region by the current flowing through the assist wiring is directed toward one end thereof.
- the first fixed magnet is fixed in the direction in which the above-mentioned one end force is also separated
- the second fixed magnet is fixed in the direction of the force toward one end thereof.
- the magnetization of the magnetized inversion region is directed in the direction toward one end thereof by the first write operation.
- the second write operation the magnetization of the magnetization switching region is directed away from one end thereof.
- the MRAM may further include an assist wiring formed so as to intersect the magnetic field inversion region.
- the direction of the magnetic field applied to the magnetization switching region by the current flowing through the assist wiring is directed toward one end thereof.
- the second write operation it flows through the assist wiring.
- the direction of the magnetic field applied to the magnetic field reversal region by the current is directed away from the force.
- the assist wiring may be provided in common for each magnetization switching region of the plurality of magnetic memory cells.
- a read current flows between the pinned layer and the magnetic recording layer via the nonmagnetic layer.
- an MRAM data read / write method includes a magnetic recording layer, which is a ferromagnetic layer, and a pinned layer connected to the magnetic recording layer via a nonmagnetic layer.
- the magnetic recording layer has a reversible magnetic field, a magnetization reversal region that overlaps the pinned layer, a first magnetization fixed region having a first fixed magnetization, and a second magnetization fixed having a second fixed magnetization. And an area.
- the magnetization switching region, the first magnetization fixed region, and the second magnetization fixed region form a three-forked path. Also, one of the first fixed magnetization and the second fixed magnet is fixed in a direction toward the magnetic inversion region, and the other is fixed in a direction away from the magnetization inversion region.
- (A) when writing the first data a step of passing a first write current from the magnetization switching region to the first magnetization fixed region; A step of flowing a second write current from the magnetization switching region to the second magnetization fixed region when writing data.
- (C) when reading the first data or the second data the step of passing a read current between the pinned layer and the magnetic recording layer through the nonmagnetic layer is provided.
- a new MRAM using a spin injection method is provided.
- the write current flows in a plane in the magnetic recording layer not in the direction penetrating the MTJ. Due to the spin transfer effect by spin electrons, the magnetization of the magnetization reversal region in the magnetic recording layer is reversed.
- the write current is supplied from one direction to the magnetic recording layer. Therefore, it is possible to simplify the control of the write current and the configuration of the peripheral circuit.
- the write current does not penetrate the MTJ during writing, deterioration of the tunnel barrier layer in the MTJ is suppressed.
- the write power is reduced as the memory cell size is reduced. The flow is reduced.
- FIG. 1 is a diagram for explaining data writing by a conventional spin injection method.
- FIG. 2 is a perspective view showing the structure of the magnetic memory cell according to the first embodiment of the present invention.
- FIG. 3 is a plan view showing the structure of the magnetic memory cell shown in FIG. 2.
- FIG. 4 is a plan view showing the principle of data writing to the magnetic memory cell shown in FIG.
- FIG. 5A is a diagram showing the distribution of magnetic flux in the magnetic recording layer obtained by simulation.
- FIG. 5B is a diagram showing the distribution of magnetic flux in the magnetic recording layer obtained by simulation.
- FIG. 6 is a plan view showing another example of the structure of the magnetic memory cell according to the first embodiment and the principle of data writing to the magnetic memory cell.
- FIG. 7 is a circuit diagram showing an example of a circuit configuration of the magnetic memory cell according to the first exemplary embodiment.
- FIG. 8 is a chart summarizing the data read / write method according to the first embodiment.
- FIG. 9 is a plan view showing an example of a circuit configuration of the memory cell array according to the first embodiment.
- FIG. 10 is a circuit diagram showing another example of the circuit configuration of the magnetic memory cell according to the first embodiment.
- FIG. 11 is a side view showing an example of a method for fixing the direction of the magnetic key in the magnetic key fixing region.
- FIG. 12 is a side view showing another example of the method for fixing the direction of the magnetic pole in the magnetic pole fixing region.
- FIG. 13A is a further illustration of a method for fixing the orientation of a magnetic key in a magnetic key fixing region. It is a top view which shows another example.
- FIG. 13B is a plan view showing still another example of the method for fixing the direction of the magnetic key in the magnetic key fixing region.
- FIG. 14 is a plan view showing still another example of the method for fixing the direction of the magnetic key in the magnetic key fixing region.
- FIG. 15 is a plan view showing another example of the structure of the magnetic memory cell according to the present invention.
- FIG. 16 is a plan view showing still another example of the structure of the magnetic memory cell according to the present invention.
- FIG. 17 is a plan view showing still another example of the structure of the magnetic memory cell according to the present invention.
- FIG. 18 is a plan view showing still another example of the structure of the magnetic memory cell according to the present invention.
- FIG. 19 is a plan view showing a structure of an MRAM according to a third embodiment of the present invention.
- FIG. 20 is a side view showing an example of the structure according to the third embodiment.
- FIG. 21 is a side view showing another example of the structure according to the third embodiment.
- FIG. 22 is a side view showing the structure of the magnetic memory cell according to the fourth embodiment of the present invention.
- FIG. 23 is a side view showing another example of the structure of the magnetic memory cell according to the fourth embodiment.
- FIG. 24 is a side view showing the structure of the magnetic memory cell according to the fifth embodiment of the present invention.
- FIG. 25A is a side view showing the structure of the magnetic memory cell according to the sixth embodiment of the present invention.
- FIG. 25B is a side view showing another example of the structure of the magnetic memory cell according to the sixth exemplary embodiment.
- the MRAM has a plurality of magnetic memory cells arranged in an array, and each magnetic memory cell has an MTJ! /.
- FIG. 2 shows the structure of the magnetic memory cell 1 (magnetoresistance element) according to the first exemplary embodiment.
- the magnetic memory cell 1 includes a magnetic recording layer 10 and a pinned layer 30 that are ferromagnetic layers, and a tunnel barrier layer 20 that is a nonmagnetic layer.
- the tunnel barrier layer 20 is sandwiched between the magnetic recording layer 10 and the pinned layer 30, and the magnetic recording layer 10, the tunnel barrier layer 20, and the pinned layer 30 form a magnetic tunnel junction (MTJ).
- the magnetic recording layer 10 plays a role corresponding to the free layer.
- the magnetic recording layer 10 is made of a soft magnetic material and contains at least one element selected from Co, Fe, and M.
- the magnetic recording layer 10 is made of NiFe.
- the magnetic recording layer 10 ⁇ , Ag, Cu, Au, B, C, N, O, Mg, Al, Si, P, Ti, Cr, Zr, Nb, Mo, Hf, Ta, W, Pd, and Pt It may contain at least one element selected from
- the tunnel barrier layer 20 is a thin insulating layer, for example.
- Examples of the tunnel barrier layer 20 include an insulating film such as an Al 2 O film, SiO film, MgO film, and A1N film.
- the pinned layer 30 includes a ferromagnetic layer having a magnetic field substantially fixed in one direction, and the ferromagnetic layer is provided adjacent to the tunnel barrier layer 20.
- the pinned layer 30 is preferably a laminated film in which ferromagnetic layers and nonmagnetic layers are alternately laminated. Further, it is desirable that at least one ferromagnetic layer of the laminated film is adjacent to an antiferromagnetic layer, and the ferromagnetic layer and the antiferromagnetic layer are exchange coupled.
- the pinned layer 30 is a laminated film of CoFeZ RuZCoFeZPtMn.
- the magnetic recording layer 10 has a first magnetization fixed region 11, a second magnetization fixed region 12, and a magnetization switching region 13 which are three different regions. is doing.
- the magnetic keys of the first magnetic key fixed region 11 and the second magnetic key fixed region 12 are fixed in predetermined directions, respectively.
- the magnetic field of the magnetization switching region (magnetization free region) 13 can be switched.
- the magnetization switching region 13 having the reversible magnetization overlaps the pinned layer 30. It is formed so that. In other words, the magnetization switching region 13 in the magnetic recording layer 10 is connected to the pinned layer 30 via the tunnel barrier layer 20.
- Both the first magnetic field fixed region 11 and the second magnetic field fixed region 12 are connected to the same end (one end) of the end portions of the magnetic field inversion region 13. That is, the first magnetic pin fixed region 11, the second magnetic pin fixed region 12, and the magnetization reversal region 13 form a “three-way”.
- the first magnetic pin fixed region 11, the second magnetic pin fixed region 12, and the magnetization switching region 13 are formed on the same plane (XY plane).
- An example of the shape of the magnetic recording layer 10 in the XY plane is shown in FIG.
- the magnetic domain inversion region 13 is formed along the X direction (X axis), and the longitudinal direction thereof is the X direction.
- the first magnetic pin fixing region 11 is formed along the S direction (S axis), and its longitudinal direction is the S direction.
- the second magnetic pin fixing region 12 is formed along the T direction (T axis), and the longitudinal direction thereof is the T direction.
- the S and T axes are oblique to the X and Y axes, and the angle between the S and T axes and the X axis is greater than 90 degrees. That is, in the present embodiment, the magnetic recording layer 10 is formed in a “Y shape”.
- the direction of the magnetic field in each region is also indicated by an arrow. Further, the projection of the pinned layer 30 and the direction of its magnetization are also indicated by dotted lines and dotted arrows.
- the direction of the magnetic layer of the pinned layer 30 is assumed to be fixed in the X direction.
- the magnetization direction of the magnetization switching region 13 that overlaps the pinned layer 30 can be reversed, and becomes + X direction or 1 X direction depending on the shape magnetic anisotropy. In other words, the magnetic field in the magnetic field inversion region 13 is allowed to be parallel or antiparallel to the magnetization of the pinned layer 30! /
- the first magnetic pole fixed region 11 has a first fixed magnetic pole Ml whose direction is fixed along the S axis.
- the second magnetic field fixed region 12 has a second fixed magnetic field M2 whose direction is fixed along the T-axis. More specifically, the direction of the first fixed magnetic field Ml is in the direction toward the magnetization switching region 13 (Toward), that is, toward the boundary between the first magnetization fixed region 11 and the magnetization switching region 13 (Toward). It is fixed in the direction.
- the direction of the second fixed magnetic field M2 is away from the magnetization reversal region 13 (Away), that is, the boundary force between the second magnetic field fixed region 12 and the magnetic magnetic field reversal region 13 is separated (Away). It is fixed in the direction. In the transition region from the first magnetized pinned region 11 to the second magnetized pinned region 12, it can be said that the direction of the magnetized magnet changes smoothly. . “Fixing the magnetic field” will be described later (Section 1-3).
- the principle of data writing for the structure shown in Fig. 3 is shown in Fig. 4.
- the magnetic force inversion region 13 and the pin layer 30 are associated with state force data “0” in which the magnetic directions are parallel.
- the magnetic force inversion region 13 and the pin layer 30 are associated with state force data “1” in which the magnetic directions are antiparallel.
- the first write current IW1 flows from the magnetization switching region 13 to the first magnetic pinned region 11.
- electrons spin electrons
- the spin of the injected electrons affects the magnetic moment of the magnetic domain inversion region 13. Since the direction of the magnetic field in the first magnetic field fixed region 11 is the direction of the magnetic force in the magnetic field inversion region 13 (rightward), a spin torque in the right direction is applied to the magnetization inversion region 13. As a result, the magnetization of the magnetization reversal region 13 is reversed, and the direction of the magnetization is changed in a direction away from the boundary ENT (+ X direction) (spin transfer magnetization switching).
- the second write current IW 2 flows from the magnetic domain inversion region 13 to the second magnetic domain fixed region 12.
- electrons spin electrons
- the spin of the injected electrons affects the magnetic moment of the magnetic domain inversion region 13. Since the direction of the magnetic field in the second magnetic field fixed region 12 is the direction away from the magnetic field inversion region 13 (leftward direction), a leftward spin torque is applied to the magnetic field inversion region 13. As a result, the magnetism of the magnetization reversal region 13 is inverted, and the orientation of the magnetism changes to the boundary ENT in the direction of the force (one X direction).
- the direction of the magnetic field in the magnetic field inversion region 13 is switched by the write currents IW 1 and IW 2 that flow in a plane in the magnetic recording layer 10. Since the write currents IW1 and IW2 do not penetrate the MTJ, deterioration of the tunnel barrier layer 20 in the MTJ is suppressed. Also, spin Data writing is performed by the memory injection method, so that the write currents IW1 and IW2 are reduced as the memory cell size is reduced.
- the first magnetic field fixed region 11 and the second magnetic field fixed region 12 serve as a supply source of electrons having different spins.
- electrons having different spins are injected into the magnetic domain inversion region 13 through the same boundary (entrance) ENT.
- the write currents IW 1 and IW 2 flow in the same direction in the magnetization switching region 13.
- the write current IW1 does not flow through the second magnetic field fixed region 12 that is not related to the supply of spin electrons, and the magnetic current inversion region 13 and the second magnetic field related to the transfer of spin torque. 1 Flows only through the magnetized fixed region 11.
- the write current IW2 does not flow to the first magnetic pinned region 11 that is not related to the supply of spin electrons, but the magnetization switching region 13 and the second magnetization fixed region related to the transfer of spin torque. Only flows 12.
- the write current IW does not flow in the magnetic field fixed region that is not the source of the spin electrons, the fixed magnetic field in the magnetic field fixed region is not affected at all. Therefore, it is possible to prevent the fixed magnetic field in the magnetic field fixed area from being inverted by spin injection of other area forces.
- FIG. 5A and FIG. 5B show the magnetic flux distribution in the magnetic recording layer 10.
- FIG. 5A corresponds to data “0”
- FIG. 5B corresponds to data “1”. These magnetic distributions are obtained by micromagnetic simulation.
- the magnetization direction smoothly changes from the first magnetic field fixed region 11 to the second magnetic field fixed region 12 and from the magnetization switching region 13 to the second magnetic field fixed region 12. .
- a short domain wall is formed between the first magnetic field fixing region 11 and the magnetic field inversion region 13.
- FIG. 5B the direction of the magnetic field is changed from the first magnetic field fixed region 11 force to the second magnetic field fixed region 12 and from the first magnetic field fixed region 11 to the magnetic field inversion region. It changes smoothly to 13.
- a short magnetic domain wall is formed between the second magnetization fixed region 12 and the magnetization switching region 13.
- the data read is as follows.
- the read current is supplied to flow through MTJ.
- the read current is supplied to the pinned layer 30. Then, it flows into the magnetic recording layer 10 via the tunnel barrier layer 20. Based on the read current or read potential, the MTJ resistance value is detected, and the magnetization direction of the magnetization switching region 13 is sensed.
- the read current may flow from the magnetic recording layer 10 to the pinned layer 30 via the tunnel barrier layer 20.
- the former is preferable in order to make the direction of the read current coincide with the direction of the write currents IWl and IW2. In that case, it becomes possible to simplify the control of the write Z read current and the configuration of the peripheral circuit.
- FIG. 6 shows another structure according to the present embodiment and the principle of writing data to the structure.
- FIG. 6 is a diagram corresponding to FIG. 4, and redundant description is omitted as appropriate.
- the direction of the first fixed magnetic field Ml of the first magnetic field fixed area 11 is fixed in the direction away from the magnetic field inversion area 13 (Away), that is, in the direction away from the boundary ENT (Away).
- the direction of the second fixed magnetic field M2 of the second magnetic field fixed region 12 is fixed in the (Toward) direction toward the magnetization switching region 13, that is, the direction toward the boundary ENT (Toward).
- the direction of the magnetic layer of the pinned layer 30 is assumed to be fixed in the + X direction. In the data “0” state, the direction of the magnetic field in the magnetic field inversion region 13 is + X direction, and in the data “1” state, the direction of the magnetic field in the magnetic field inversion region 13 is one X direction. It is.
- the first write current IW 1 flows from the magnetization switching region 13 to the first magnetic pinned region 11.
- electrons spin electrons
- the magnetic field in the magnetic field reversal region 13 is reversed, and the direction of the magnetic field changes to the boundary ENT in the direction (X direction).
- the second write current IW2 flows from the magnetization switching region 13 to the second magnetization fixed region 12.
- FIG. 7 shows an example of a circuit configuration of the magnetic memory cell 1.
- two MOS transistors TR 1 and TR 2 are provided for one magnetic memory cell 1.
- One of the source Z drain of the first MOS transistor TR1 is connected to the ground line GND, and the other is connected to one end (the side opposite to the boundary ENT) of the first magnetic field fixing region 11.
- one of the source Z and drain of the second MOS transistor TR2 is connected to the ground line GND, and the other is connected to one end (the side opposite to the boundary ENT) of the second magnetic pin fixing region 12.
- the gate of the first MOS transistor TR1 is connected to the first word line WL1, and the gate of the second MOS transistor TR2 is connected to the second word line WL2.
- first bit line BL1 is connected to one end of the magnetization switching region 13 (on the side opposite to the boundary ENT).
- the first bit line BL1 is a write wiring for supplying write currents IW1 and IW2 to the magnetization switching region 13 (see FIGS. 4 and 6).
- the second bit line BL2 is connected to the pinned layer 30 that is one end of the MTJ.
- the second bit line BL2 is a read wiring for supplying a read current to the MTJ.
- FIG. 8 shows a summary of a data read / write method in the case of the circuit configuration shown in FIG.
- the potentials of the first word line WL1 and the second word line WL2 are set to “High” and “Low”, respectively.
- the first MOS transistor TR1 is turned on and the second MOS transistor TR2 is turned off.
- the first bit line BL1 (write wiring) is selected and its potential is set to 'High', while the second bit line BL2 is set to 'O pen'.
- the write current IW1 flows from the first bit line BL1 to the ground line GND via the magnetization inversion region 13, the first magnetic field fixed region 11, and the first MOS transistor TR1.
- the potentials of the first word line WL1 and the second word line WL2 are set to “Low” and “High”, respectively.
- the first MOS transistor TR1 is turned off and the second MOS transistor TR2 is turned on.
- the first bit line BL1 (write Wiring) is selected and its potential force is set to “High”, while the second bit line BL2 is set to “Open”, so that the second write current IW2 is generated from the first bit line BL1. Then, the current flows through the magnetic field inversion region 13, the second magnetic field fixed region 12, and the second MOS transistor TR2 to the round line GND.
- the potential of at least one of the first word line WL1 and the second word line WL2 is set to “High”.
- the first MOS transistor TR1 and the second MOS transistor TR2 is turned on.
- the second bit line BL2 (read wiring) is selected and set to its high potential.
- the first bit line BL1 is set to "Open”. 2 Flows from the bit line BL2 to the ground line GND via the MTJ and the magnetic recording layer 10. The magnitude of the read current is set so small that the direction of the magnetic field in the magnetization reversal region 13 does not change. Has been.
- FIG. 9 shows a memory cell array in which a plurality of magnetic memory cells 1 are arranged in an array.
- Each magnetic memory cell 1 has the same configuration as that shown in FIG.
- the magnetic memory cell la is connected to the word lines WLla and WL2a, the bit lines BL1 and BL2, and the ground line.
- the magnetic memory cell lb is connected to the word lines WLlb and WL2b, the bit lines BL1 and BL2, and the ground line.
- the word line WL is shared by a group of magnetic memory cells arranged along the X axis.
- the bit line BL is shared by a group of magnetic memory cells arranged along the Y axis.
- the magnetic memory cell la has a “first pattern” in which the magnetic domain inversion region 13 protrudes to the right (+ X direction).
- the magnetic memory cell lb has a “second pattern” in which the magnetization switching region 13 protrudes to the left ( ⁇ X direction). That is, the magnetic memory cells la and lb arranged along the Y axis have a line-symmetric relationship with respect to the Y axis.
- the memory cell array shown in Figure 9 is designed so that the first and second patterns appear alternately! In that case, the area of the cell array can be reduced as compared with the case where only one of the patterns appears, which is preferable.
- FIG. 10 shows another example of the circuit configuration of the magnetic memory cell 1.
- one of the source Z drain of the first MOS transistor TR1 is connected to the first ground line GND1, and the other is connected to one end of the first magnetic pinned region 11.
- the second MOS transistor One of the source Z drain of the transistor TR2 is connected to the second ground line GND2, and the other is connected to one end of the second magnetic pin fixing region 12.
- the gates of the MOS transistors TR1 and TR2 are connected to a common word line WL.
- a first bit line BL1 write wiring
- a second bit line BL2 readout wiring
- FIG. 11 is a side view showing the magnetic memory cell 1 having the magnetic pin fixing means.
- the magnetic memory cell 1 includes a first pinning layer 41 and a second pinning layer 42 as magnetic pin fixing means.
- the first pinning layer 41 applies a bias magnetic field in the ⁇ S direction to the first magnetic pinned region 11.
- the second pinning layer 42 applies a bias magnetic field in the + T direction to the second magnetic field fixed region 12.
- the first pinning layer 41 includes a ferromagnetic layer in which a magnetic field is fixed in the S direction, and the ferromagnetic layer is in close contact with the first magnetic field fixed region 11. Is formed.
- the first pinning layer 41 fixes the direction of the fixed magnetic field Ml of the first magnetization fixed region 11 in the 1 S direction by “exchange coupling”.
- the second pinning layer 42 includes a ferromagnetic layer in which the magnetic flux is fixed in the + T direction, and the ferromagnetic layer is formed so as to be in close contact with the second magnetization fixed region 12. ing.
- the second pinning layer 42 also fixes the direction of the fixed magnetic layer M2 of the second magnetic layer fixed region 12 in the + T direction by exchange coupling.
- the coupling layers 41 and 42 are, for example, a CoFeZPtMn laminated film using an exchange bias.
- the pinning layers 41 and 42 may include only a ferromagnetic layer (CoFe or the like), or may include only an antiferromagnetic layer (PtMn or the like). Piing layers 41 and 42 are composed of ferromagnetic and antiferromagnetic layers. Both may be included. Further, the pinning layers 41 and 42 may further include an intermediate layer (Ru or the like) provided between the ferromagnetic layer and the magnetic pinned regions 11 and 12. The ferromagnetic layer and the magnetic pinned regions 11 and 12 may be ferromagnetically coupled or antiferromagnetically coupled. The ferromagnetic layer may be a multilayer film magnetically coupled via an intermediate layer (Ru or the like).
- FIG. 12 is a side view showing the magnetic memory cell 1 having the magnetic pin fixing means.
- the magnetic memory cell 1 includes a first pinning layer 41 and a second pinning layer 42 as magnetic pin fixing means.
- the first pinning layer 41 applies a bias magnetic field in the ⁇ S direction to the first magnetic pinned region 11.
- the second pinning layer 42 applies a bias magnetic field in the + T direction to the second magnetic field fixed region 12.
- the first pinning layer 41 includes a ferromagnetic layer having a magnetic field fixed in the + S direction, and the ferromagnetic layer is formed away from the first magnetization fixed region 11. ing.
- the first pinning layer 41 fixes the direction of the fixed magnetic field Ml of the first magnetization fixed region 11 in the 1 S direction by “static coupling”.
- the second pinning layer 42 includes a ferromagnetic layer whose magnetic field is fixed in the T direction, and the ferromagnetic layer is formed away from the second magnetization fixed region 12.
- the second pinning layer 42 also fixes the direction of the fixed magnetic field M2 of the second magnetic field fixed region 12 in the + T direction by magnetostatic coupling.
- the pinning layers 41 and 42 are, for example, a CoFe / PtMn multilayer film using an exchange bias.
- the pinning layers 41 and 42 may include only a ferromagnetic layer (CoFe or the like).
- the pinning layers 41 and 42 may include both a ferromagnetic layer and an antiferromagnetic layer.
- the ferromagnetic layer may be a multilayer film that is magnetically coupled via an intermediate layer (such as Ru).
- the first pinning layer 41 and the second pinning layer 42 are provided below the first magnetic pinned region 11 and the second magnetic pinned region 12, respectively.
- the first pinning layer 41 and the second pinning layer 42 may be provided below or on the side of the first magnetic pinned region 11 and the second magnetic pinned region 12, respectively.
- a single pinning layer 40 may be provided.
- the pinning layer 40 is provided so as to overlap at least the first magnetic pinned region 11 and the second magnetic pinned region 12.
- the magnetization direction of the pinning layer 40 is fixed in the -Y direction (the direction of the direction from the first magnetic layer fixed region 11 to the second magnetic layer fixed region 12).
- the magnetization of the pinning layer 40 affects the magnetic pinned regions 11 and 12 by exchange coupling or magnetostatic coupling.
- the magnetic fields of the magnetization fixed regions 11 and 12 are each stabilized along the longitudinal direction by the shape magnetic anisotropy. As a result, as shown in the figure, the orientation of the magnetic keys in the magnetic key fixing regions 11 and 12 is fixed.
- the magnetizing fixing method shown in Fig. 13A and Fig. 13B is possible even with the structural force according to the present embodiment.
- the magnetization directions of the magnetic pole fixed regions 11 and 12 are the same, not the opposite. Therefore, it is not necessary to fix the magnetic keys 11 and 12 separately.
- By using one of the above-described pinning layers 40 it is possible to fix the direction of the magnetic poles of the magnetic pole fixing regions 11 and 12.
- Figure 14 summarizes the other magnetic pin fixing methods.
- the magnetization fixed regions 11 and 12 are formed so as to have crystal magnetic anisotropy along the Y-axis direction (the direction in which the first magnetic layer fixed region 11 and the second magnetic layer fixed region 12 are arranged).
- the magnetic poles of the magnetic pole fixed regions 11 and 12 are stabilized along the longitudinal direction by the magnetocrystalline anisotropy and the shape magnetic anisotropy, respectively.
- An external magnetic field in the Y direction may be applied uniformly to the magnetic memory cell 1. For example, a few Oe magnets should be provided in the package
- adjacent magnetic memory cells la and lb may be magnetically interacted with each other.
- the fixed magnetic field of the second magnetic field fixed region 12a of the magnetic memory cell la and the first magnetic field fixed region l ib of the adjacent magnetic memory cell lb are fixed. And influence each other. This stabilizes the magnetization and improves thermal disturbance. Resistance is improved. To increase the effect, the distance between adjacent magnetic memory cells la and lb should be reduced. Further, the various magnetization fixing methods described above may be applied in combination. In that case, the fixing of the magnetic field is further stabilized, and the thermal disturbance resistance is further improved.
- a new data read / write method is provided for a randomly accessible MRAM.
- Data writing is realized by unidirectional spin injection in 10 magnetic recording layers.
- Data reading is realized by using MTJ. The effect of this is as follows.
- the write current scaling is improved as compared to the asteroid method and the toggle method.
- the reversal magnetic field necessary for reversing the magnetization of the magnetization reversal region is substantially in inverse proportion to the memory cell size. That is, the write current tends to increase as the memory cell is miniaturized.
- the magnetization reversal threshold depends on the current density. Since the current density increases as the memory cell size is reduced, the write current can be reduced as the memory cell size is reduced. In other words, it is not necessary to increase the write current even if the memory cell size is reduced. In this sense, the write current scaling is improved. This is important for realizing large-capacity MRAM.
- the current magnetic field conversion efficiency is increased as compared with the asteroid method and the toggle method.
- the write current is consumed by Joule heat.
- the spin injection method the write current directly contributes to the spin transfer. Therefore, the current magnetic field conversion efficiency increases. This If the manufacturing process is complicated, an increase in wiring inductance is prevented.
- the MTJ tunnel barrier layer 20
- the conventional spin injection magnetization reversal is realized by the CPP (Current Perpendicular to Plane) method, and the write current is injected perpendicularly to the film surface.
- the write current when writing data was much larger than the read current, which could destroy the tunnel barrier layer 20.
- the current path for reading and the current path for writing are separated. Specifically, when writing data, the write currents IW1 and IW2 do not pass through the MTJ and flow in the plane of the magnetic recording layer 10. When writing data, it is not necessary to inject a large current perpendicular to the MTJ film surface. Therefore, the deterioration of the tunnel barrier layer 20 at the MTJ is suppressed.
- the write current can be easily controlled as compared with the conventional spin injection method.
- the conventional spin injection method particularly the “domain wall motion method”
- electrons having different spins are injected into the magnetic domain inversion region 13 through the same boundary ENT, and the write currents IW1 and IW2 flow in the same direction (FIGS. 4 and 4). 6).
- the write currents IW1 and IW2 are supplied from one direction to the magnetization switching region 13 of the magnetic recording layer 10. Therefore, the control of the write current and the configuration of the peripheral circuit are simplified.
- the magnetization of the magnetization fixed region is stabilized as compared with the conventional domain wall motion method.
- the write current is also applied to the magnetic domain fixed region that is not the source of spin electrons.
- the write current does not flow in the magnetization fixed region that is not the spin electron supply source. Therefore, it is possible to prevent the fixed magnetic key of the magnetic key fixed region from being inverted by spin injection from other regions.
- the above-described effects can be obtained simultaneously.
- the technology according to the present invention is extremely useful for realizing highly integrated 'high speed operation' and low power consumption MRAM.
- FIG. 15 shows parameters that define the shape of the magnetic recording layer 10.
- the length of the first magnet 11 fixed region 11 and The width is expressed by and. It is assumed that the length and width of the second magnetization fixed region 12 are represented by 1 and w, respectively.
- the length and width of the magnetization switching region 13 are each 1
- first magnetic field fixed region 11 and the second magnetic field fixed region 12 are formed.
- the angle that is, the angle between the S axis and the heel axis is represented by 0.
- the angle formed by the second magnetic field fixed region 12 and the magnetic field inversion region 13 that is, the angle formed by the vertical axis and the X axis is represented by ⁇ .
- the parameters 1 and w may be set to arbitrary values, respectively.
- Parameters 0 and ⁇ are also possible.
- Each may be arbitrarily set within the range of 90 degrees to 180 degrees. However, preferably, the parameters ⁇ and ⁇ are set to the same value. As a result, the first write operation and the second write
- width W and width W are the same value.
- the magnetic recording layer 10 is preferably set to the same value. That is, it is preferable that the magnetic recording layer 10 has a mirror-symmetric shape with respect to the X axis. As a result, it is expected that the magnitudes of the first write current IW1 and the second write current IW2 match.
- FIG. 16 shows another shape of the magnetic recording layer 10.
- the first magnetization fixed region 11 and the second magnet fixed region 12 are formed to be curved.
- the extending direction of the first magnetic pinned region 11 changes from the ⁇ direction to the X direction as it approaches the magnetization switching region 13.
- the heel direction force changes in the X direction as it approaches the magnetization switching region 13.
- the X component of the magnetic moment of the spin electrons flowing from the magnetic domain fixed regions 11 and 12 into the magnetic domain inversion region 13 increases. Accordingly, the write currents IW1 and IW2 are reduced.
- FIG. 17 shows still another shape of the magnetic recording layer 10.
- the magnetization reversal region 13 is formed wider than the other regions, and the width w is equal to the width w and the width w.
- the magnetic pole fixed regions 11 and 12 are connected to the boundary ⁇ of the magnetization switching region 13 and the boundary ⁇ is formed in a straight line. Such a shape is also included in the “character shape”.
- FIG. 18 shows still another shape of the magnetic recording layer 10.
- the magnetic recording layer 10 includes a first side surface J13 extending over the magnetization switching region 13 and the first magnetization fixed region 11 1, and a second side surface J23 extending over the magnetic switching region 13 and the second magnetic switching region 12. And a third side face J12 extending over the first magnetic pin fixed region 11 and the second magnetic pin fixed region 12.
- these side surfaces J13, J23, and J12 are formed smoothly. As a result, spin electrons are supplied smoothly and the write currents IW1 and IW2 are reduced.
- FIG. 19 shows an example of a configuration in which an assist wiring 50 for assisting magnetic reversal is provided.
- the assist wiring 50 is provided so as to intersect the magnetic field inversion region 13 of the magnetic memory cell 1.
- a plurality of magnetic memory cells 1 are arranged along the Y-axis, and one assist wiring 50 is provided for each magnetic domain inversion region 13 of the plurality of magnetic memory cells 1. Commonly provided.
- the write currents IW1 and IW2 are supplied, and at the same time, the assist current 50las is supplied.
- the direction of the magnetic field (assist magnetic field) applied to the magnetic field reversal region 13 by the assist current las is the direction that assists the magnetic field reversal.
- the direction of the assist magnetic field is also set to the + X direction.
- the direction of the assist current las is controlled so that the magnetic reversal is assisted.
- FIG. 20 is a side view of the structure shown in FIG.
- the assist wiring 50 is provided below the magnetization switching region 13 so as to intersect the magnetization switching region 13.
- the assist wiring 50 may be provided above the magnetic domain inversion region 13.
- the assist wiring 50 may have a yoke wiring structure.
- the wiring 50 is composed of a metal wiring 51 and a magnetic layer 52, and is covered with a surface force magnetic layer 52 that does not face the magnetic domain inversion region 13 in the surface of the metal wiring 51.
- the magnetic layer 52 may cover only the bottom surface of the metal wiring 51.
- Such a yoke wiring structure increases the assist magnetic field, and the write currents IW1 and IW2 can be further reduced.
- an auxiliary magnetic layer 53 is further provided between the magnetic domain inversion region 13 and the assist wiring 50.
- the assist current las flows through the assist wiring 50, the magnetic field generated thereby magnetizes the auxiliary magnetic layer 53.
- the magnetization of the auxiliary magnetic layer 53 assists magnetic reversal by magnetic interaction (exchange coupling, magnetostatic coupling).
- the auxiliary magnetic layer 53 plays a role of amplifying the assist magnetic field.
- the assist wiring 50 may be provided separately for each magnetic memory cell 1. In order to reduce the number of the assist wirings 50, it is preferable that one assist wiring 50 is provided in common for the plurality of magnetic memory cells 1, as shown in FIG. However, in that case, the assist magnetic field is also applied to the non-selected cells. Therefore, the magnetism of the magnetization reversal region 13 is designed so that magnetic reversal occurs by a combination of spin injection and assist magnetic field.
- the magnetic recording layer 10 may be composed of a plurality of magnetically coupled ferromagnetic layers! That is, the magnetic recording layer 10 may have a laminated structure (multilayer structure).
- Examples of magnetic coupling include ferromagnetic coupling, antiferromagnetic coupling, magnetostatic coupling, and RKKY coupling.
- SAF synthetic anti-ferromagnetic
- the magnetic recording layer 10 includes a first ferromagnetic layer 10 a and a second ferromagnetic layer 10 b that are antiferromagnetically coupled via the intermediate layer 14.
- the intermediate layer 14 is a nonmagnetic layer, for example, a Ru layer.
- the first ferromagnetic layer 10a has a first magnetic pinned region lla, a second magnetization fixed region 12a, and a magnetization switching region 13a.
- the second ferromagnetic layer 10b has only the magnetization switching region 13b. This magnetic domain inversion region 13 b is adjacent to the pinned layer 30 through the tunnel barrier layer 20.
- the magnetization switching regions 13a and 13b are antiferromagnetically coupled, and their magnetization directions are reversed.
- the other magnetization is also reversed.
- a write current flows through the first ferromagnetic layer 10a.
- the magnetization of the magnetization switching region 13a is reversed by spin injection. Accordingly, the magnetization of the magnetic domain inversion region 13b of the second ferromagnetic layer 10b is also reversed. Data is read by using the pinned layer 30 and sensing the magnetic field direction of the magnetic field inversion region 13b.
- the same effects as those of the above-described embodiments can be obtained. Further, since the effective volume of the magnetic recording layer 10 is increased by the laminated structure, resistance to thermal disturbance is improved. Furthermore, the degree of freedom in device design increases for the following reasons.
- the magnetic recording layer 10 is composed of the first ferromagnetic layer 10a, the second ferromagnetic layer 10b, and the intermediate layer 14, the write characteristics are mainly governed by the first ferromagnetic layer 10a, and the read characteristics (MR ratio, etc.) are Mainly dominated by the second ferromagnetic layer 10b.
- the material of the second ferromagnetic layer 10b adjacent to the tunnel barrier layer 20 a material (CoFe, CoFeB, etc.) that enhances the read characteristics is used, while the first ferromagnetic layer 10a in which the write current flows is used.
- a material NiFe or the like that improves the writing characteristics can be used. That is, the characteristics of each ferromagnetic layer can be independently controlled freely according to the desired characteristics. Write characteristics and read characteristics can be improved separately. Thus, the degree of freedom in element design is improved by making the magnetic recording layer 10 multilayer. This advantage cannot be realized with the CPP spin injection method. This is because in the case of the CPP spin injection method, both the write characteristics and the read characteristics are dominated by the ferromagnetic layer adjacent to the tunnel barrier layer.
- the intermediate layer 14 is fabricated to have the same planar shape as the first ferromagnetic layer 10a. In this case, the intermediate layer 14 plays a role of protecting the first ferromagnetic layer 10a as well as the acid etching force during the manufacturing process.
- FIG. 23 shows a modification.
- the first ferromagnetic layer 10a has a first magnetization fixed region lla, a second magnetic domain fixed region 12a, and a magnetic domain reversal region 13a.
- the second ferromagnetic layer 10b also has a first magnetic pinned region llb, a second magnetic pinned region 12b, and a magnetization reversal region 13b.
- the direction of the fixed magnetic field in the first magnetic field fixed region l la and l ib is opposite.
- the directions of the fixed magnetic fields in the second magnetic field fixed areas 12a and 12b are opposite. Further, the magnetization directions of the magnetization switching regions 13a and 13b are reversed.
- the tunnel barrier layer 20 is fabricated to have the same planar shape as the magnetic recording layer 10. In this case, the tunnel barrier layer 20 also serves to protect the magnetic recording layer 10 from an acid etchant during the manufacturing process.
- FIG. 24 is a side view showing the structure of the magnetic memory cell 1 according to the fifth embodiment of the present invention.
- the magnetic recording layer 10 is formed on the seed layer 60.
- the seed layer 60 is a layer for controlling crystal growth during the formation of the magnetic recording layer 10.
- the crystallinity of the magnetic recording layer 10 can be controlled so that the write characteristics and the read characteristics are improved.
- a material having high electrical resistance is used as the material of the seed layer 60 so that the write current does not selectively flow only to the seed layer 60.
- the tunnel barrier layer 20 has the same planar shape as the magnetic recording layer 10.
- the thickness of the tunnel barrier layer 20 is uniform.
- a part of the tunnel barrier layer 20 may be removed by etching when the pinned layer 30 is formed.
- the tunnel barrier layer 20 plays a role of protecting the magnetic recording layer 10 by the acid etching force during the manufacturing process.
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- 2007-03-20 JP JP2008510822A patent/JPWO2007119446A1/ja not_active Withdrawn
- 2007-03-20 US US12/294,397 patent/US7848137B2/en active Active
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JP2005191032A (ja) * | 2003-12-24 | 2005-07-14 | Toshiba Corp | 磁気記憶装置及び磁気情報の書込み方法 |
Cited By (15)
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JP5201536B2 (ja) * | 2006-12-12 | 2013-06-05 | 日本電気株式会社 | 磁気抵抗効果素子及びmram |
WO2009037909A1 (ja) * | 2007-09-19 | 2009-03-26 | Nec Corporation | 磁気ランダムアクセスメモリ |
JP5445133B2 (ja) * | 2007-09-19 | 2014-03-19 | 日本電気株式会社 | 磁気ランダムアクセスメモリ、その書き込み方法、及び磁気抵抗効果素子 |
WO2009038004A1 (ja) * | 2007-09-20 | 2009-03-26 | Nec Corporation | 磁気ランダムアクセスメモリ |
WO2009110537A1 (ja) * | 2008-03-07 | 2009-09-11 | 日本電気株式会社 | Mram混載システム |
JP5488833B2 (ja) * | 2008-03-07 | 2014-05-14 | 日本電気株式会社 | Mram混載システム |
JP5445970B2 (ja) * | 2008-04-02 | 2014-03-19 | 日本電気株式会社 | 磁気抵抗効果素子及び磁気ランダムアクセスメモリ |
JP2009252909A (ja) * | 2008-04-03 | 2009-10-29 | Nec Corp | 磁気抵抗効果素子、及び磁気ランダムアクセスメモリ |
US8559214B2 (en) | 2008-12-25 | 2013-10-15 | Nec Corporation | Magnetic memory device and magnetic random access memory |
WO2010074132A1 (ja) * | 2008-12-25 | 2010-07-01 | 日本電気株式会社 | 磁気メモリ素子及び磁気ランダムアクセスメモリ |
US8687414B2 (en) | 2008-12-25 | 2014-04-01 | Nec Corporation | Magnetic memory element and magnetic random access memory |
JP5505312B2 (ja) * | 2008-12-25 | 2014-05-28 | 日本電気株式会社 | 磁気メモリ素子及び磁気ランダムアクセスメモリ |
WO2010087389A1 (ja) * | 2009-01-30 | 2010-08-05 | 日本電気株式会社 | 磁気メモリ素子、磁気メモリ |
US8994130B2 (en) | 2009-01-30 | 2015-03-31 | Nec Corporation | Magnetic memory element and magnetic memory |
JP2015060609A (ja) * | 2013-09-18 | 2015-03-30 | 株式会社東芝 | 磁気記憶装置及びその駆動方法 |
Also Published As
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JPWO2007119446A1 (ja) | 2009-08-27 |
US7848137B2 (en) | 2010-12-07 |
US20090251955A1 (en) | 2009-10-08 |
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