JP2015207775A - Spin transfer torque storage element and storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage element which has high coercive force and can improve thermal stability without increasing write current.SOLUTION: A storage element 3 comprises: a storage layer 17 for holding information by a magnetization state of a magnetic substance; a magnetization fixed layer 15 having magnetization which serves as reference for the information stored in the storage layer 17; an intermediate layer 16 of a nonmagnetic substance provided between the storage layer 17 and the magnetization fixed layer 15; a magnetic coupling layer 19 provided adjacent to the magnetization fixed layer 15 and provided on an opposite side to the intermediate layer 16; and a high coercive force layer 20 provided adjacent to the magnetic coupling layer 19. The storage element stores information by inverting magnetization of the storage layer 17 by utilizing spin torque magnetization reversal occurring in association with current flowing in a lamination direction of a layer structure having the storage layer 17, the intermediate layer 16, and the magnetization fixed layer 15. The magnetization coupling layer 19 is composed of a laminate structure of two layers.

Description

  The present disclosure includes a storage layer that stores a magnetization state of a ferromagnetic layer as information, and a magnetization fixed layer in which the magnetization direction is fixed, and changes the magnetization direction of the storage layer by flowing a current. And a storage device including the storage element.

JP 2004-193595 A JP 2009-081215 A

Nature Materials., Vol 9, p. 721 (2010)

In information equipment such as a computer, a high-speed and high-density DRAM is widely used as a random access memory.
However, since DRAM (Dynamic Random Access Memory) is a volatile memory in which information disappears when the power is turned off, a nonvolatile memory in which information does not disappear is desired.

As a candidate for a nonvolatile memory, a magnetic random access memory (MRAM) that stores information by magnetization of a magnetic material has attracted attention and is being developed.
As a method for storing the MRAM, for example, as described in Patent Document 1, a spin torque type MRAM that reverses the magnetization of a magnetic material responsible for storage by a spin torque flowing between two magnetic materials has a relatively simple structure. It attracts attention because of the large number of rewrites.

In many cases, a spin torque magnetization reversal storage element is configured by MTJ (Magnetic Tunnel Junction) as in MRAM. In this configuration, when spin-polarized electrons passing through a magnetic layer fixed in a certain direction enter another free (non-fixed direction) magnetic layer, a torque is applied to the magnetic layer (this is spinned). The free magnetic layer is inverted when a current exceeding a certain threshold is passed. The rewriting of 0/1 is performed by changing the polarity of the current.
The absolute value of the current for this inversion is 1 mA or less for an element having a scale of about 0.1 μm. In addition, since this current value decreases in proportion to the element volume, scaling is possible. Further, since a word line for generating a current magnetic field for storage required in the MRAM is unnecessary, there is an advantage that the cell structure is simplified.

  Hereinafter, the MRAM using spin torque magnetization reversal is referred to as “spin torque type MRAM” or “ST-MRAM (Spin Torque-Magnetic Random Access Memory)”. Spin torque magnetization reversal may also be referred to as spin injection magnetization reversal.

As ST-MRAM, for example, those using in-plane magnetization as described in Patent Document 1 and those using perpendicular magnetization as in Patent Document 2 have been developed.
A material using in-plane magnetization has a high degree of freedom of material, and the method of fixing the magnetization is relatively easy. However, when a perpendicular magnetization film is used, materials having perpendicular magnetic anisotropy are limited.

  In recent years, for example, an interface anisotropy type perpendicular magnetization film using perpendicular magnetic anisotropy that appears at the crystal interface between Fe and oxide as in Non-Patent Document 1 has attracted attention. When interface anisotropy is used, a perpendicular magnetization film can be obtained using an FeCoB alloy as a magnetic material and MgO as an oxide, and both a high magnetoresistance ratio (MR ratio) and perpendicular magnetization can be achieved. Since it is promising for both of the magnetization fixed layers, application to a perpendicular magnetization type spin torque MRAM is expected.

  By the way, in order to use the interface anisotropic material for the spin torque MRAM, at least the coercivity of the magnetic material of the magnetization fixed layer must be sufficiently larger than the coercivity of the storage layer. In order to increase the coercivity of the magnetization fixed layer, a high coercivity layer having a large magnetocrystalline anisotropy may be magnetically coupled to the magnetization fixed layer to reinforce the coercivity of the magnetization fixed layer. In addition, if a magnetic coupling layer that forms strong magnetic coupling is inserted between the pinned magnetic layer and the high coercive force layer at an appropriate thickness, and the magnetic pinned layer and the high coercive force layer are magnetically coupled in antiparallel, the magnetization fixed The leakage magnetic field from the layer and the high coercive force layer cancel each other, and the magnetic influence on the storage layer is reduced, which is preferable. However, when a high coercive force layer and a magnetic coupling layer are stacked on the magnetization fixed layer, effects such as a decrease in MR ratio and a decrease in heat-resistant temperature are produced as compared with the case of only the magnetization fixed layer.

  Therefore, the present disclosure has been made on the basis of such recognition, and in the spin torque MRAM, the vertical coercive force is large and the heat resistance (thermal stability) is excellent so that stable operation is possible. The object is to realize a magnetization fixed layer.

The storage element of the present disclosure includes a storage layer that holds information according to a magnetization state of a magnetic material, a magnetization fixed layer that has a magnetization serving as a reference of information stored in the storage layer, and the storage layer and the magnetization fixed layer. A non-magnetic intermediate layer provided therebetween, a magnetic coupling layer provided adjacent to the magnetization fixed layer and on the opposite side of the intermediate layer, and a high coercivity layer provided adjacent to the magnetic coupling layer. And
Information is stored by reversing the magnetization of the storage layer by utilizing the spin torque magnetization reversal that occurs with the current flowing in the stacking direction of the layer structure having the storage layer, the intermediate layer, and the magnetization fixed layer. In addition, the magnetic coupling layer has a two-layer structure.
Of the two layers of the magnetic coupling layer, the layer on the high coercive force layer side is made of at least one of Ru, Re, and Os. Of the two layers of the magnetic coupling layer, the layer on the magnetization fixed layer side is Cu, Ag, It is made of at least one of Au, and the layer thickness is 0.1 nm to 0.5 nm.

  A storage device according to the present disclosure includes a storage element that holds information according to a magnetization state of a magnetic body, and two types of wirings that intersect each other, and the storage element includes a storage layer that holds information according to a magnetization state of the magnetic body; A magnetization pinned layer having magnetization serving as a reference for information stored in the storage layer, an intermediate layer made of a nonmagnetic material provided between the storage layer and the magnetization pinned layer, and adjacent to the magnetization pinned layer, A layered structure including a magnetic coupling layer provided on the opposite side of the intermediate layer and a high coercive force layer provided adjacent to the magnetic coupling layer, the storage layer, the intermediate layer, and the magnetization fixed layer. Information is stored by reversing the magnetization of the storage layer using spin torque magnetization reversal that occurs with a current flowing in the direction, and the magnetic coupling layer has a two-layer structure, and the magnetic coupling Of the two layers, The layer on the coercive force layer side is made of at least one of Ru, Re, and Os. Of the two layers of the magnetic coupling layer, the layer on the magnetization fixed layer side is made of at least one of Cu, Ag, and Au. The thickness is 0.1 nm to 0.5 nm, the memory element is disposed between the two types of wiring, and the current in the stacking direction flows through the memory element through the two types of wiring. Spin torque magnetization reversal occurs.

  In the present disclosure, the storage element has a structure in which a magnetic coupling layer provided adjacent to the magnetization fixed layer and on the opposite side of the intermediate layer and a high coercivity layer provided adjacent to the magnetic coupling layer are provided. As a result, a coercive force can be increased and an element having excellent thermal stability can be obtained.

According to the present disclosure, since a memory element having perpendicular magnetic anisotropy can be easily obtained, it is possible to sufficiently ensure the thermal stability that is the information retention capability and to configure a memory element that has an excellent characteristic balance. . Thereby, an operation error can be eliminated and a sufficient operation margin of the memory element can be obtained.
Therefore, a highly reliable memory that operates stably can be realized.
In addition, the write current can be reduced, so that power consumption when writing to the memory element can be reduced.
Therefore, the power consumption of the entire storage device can be reduced.

1 is a perspective view of a schematic configuration of a storage device according to an embodiment. It is sectional drawing of the memory | storage device of embodiment. It is sectional drawing which shows the layer structure of the memory element of embodiment. It is explanatory drawing of the layer structure of the sample used in experiment. It is a figure showing the relationship between the thickness of a magnetic coupling layer (Ru), and the magnitude | size of a magnetization reversal change. It is a figure showing the relationship between the thickness of a magnetic coupling layer (Ru) and the magnitude | size of a magnetization reversal as two layers of a magnetic coupling layer (Ru) and a magnetic coupling layer (Ta). It is a figure showing the relationship between the thickness of a magnetic coupling layer (Ru), and the magnitude | size of the magnetic field of magnetization reversal when changing the thickness of a magnetic coupling layer (Ta). Relationship between magnetic reversal magnetic field magnitude after 300 ° C. heat treatment when the magnetic coupling layer (Ta) is made of an element other than Ta, such as Cr, and the thickness of the magnetic coupling layer (Ru) is changed. FIG. Relationship between the magnetic reversal magnetic field after 350 ° C heat treatment when the magnetic coupling layer (Ta) is made of an element other than Ta, such as Cr, and the thickness of the magnetic coupling layer (Ru) is changed. FIG. It is a figure showing the relationship between the magnitude | size of the magnetic field of a magnetization reversal when the material of a magnetic coupling layer (Ta) is made into elements other than Ta, Cu etc., and the thickness and the thickness of a magnetic coupling layer (Ru) are changed. . It is a figure of the layer structure of the sample for a measurement of magnetoresistive ratio (MR ratio).

Hereinafter, embodiments of the present disclosure will be described in the following order.
<1. Configuration of Storage Device of Embodiment>
<2. Outline of Memory Element of Embodiment>
<3. Specific Configuration of Embodiment>
<4. Experiments on Embodiments>

<1. Configuration of Storage Device of Embodiment>

First, the configuration of the storage device according to the embodiment of the present disclosure will be described.
Schematic diagrams of the storage device (ST-MRAM) are shown in FIGS. 1 is a perspective view, and FIG. 2 is a cross-sectional view.

  As shown in FIG. 1, a drain region 8, a source region 7, and a transistor constituting a selection transistor for selecting each storage element 3 in a portion separated by an element isolation layer 2 of a semiconductor substrate 10 such as a silicon substrate. A gate electrode 1 is also formed. Of these, the gate electrode 1 also serves as a word line extending in the front-rear direction in FIG.

The drain region 8 is formed in common with the left and right selection transistors in FIG. 2, and a wiring 9 is connected to the drain region 8.
A storage element 3 having a storage layer whose magnetization direction is reversed by spin torque magnetization reversal is disposed between the source region 7 and the bit line 6 disposed above and extending in the left-right direction in FIG. Yes. The storage element 3 is constituted by, for example, a magnetic tunnel junction element (MTJ element).

As shown in FIG. 2, the memory element 3 has two magnetic layers 15 and 17. Of these two magnetic layers 15, 17, one magnetic layer is a magnetization fixed layer 15 in which the direction of the magnetization M 15 is fixed, and the other magnetic layer is a magnetization free layer, that is, a storage layer 17 in which the direction of the magnetization M 17 changes. And
The storage element 3 is connected to the bit line 6 and the source region 7 via the upper and lower contact layers 4, respectively.
As a result, a current can be passed through the storage element 3 to reverse the direction of the magnetization M17 of the storage layer 17 by spin injection.

  In such a memory device, it is necessary to perform writing at a current equal to or lower than the saturation current of the selection transistor, and it is known that the saturation current of the transistor decreases with miniaturization. For this, it is preferable to improve the efficiency of the spin transfer and reduce the current flowing through the memory element 3.

Further, in order to increase the read signal, it is necessary to secure a large magnetoresistance change rate. For that purpose, the above-described MTJ structure is adopted, that is, between the two magnetic layers 15 and 17. It is effective to adopt a configuration of the memory element 3 in which the layer is a tunnel insulating layer (tunnel barrier layer).
When the tunnel insulating layer is used as the intermediate layer in this way, the amount of current flowing through the memory element 3 is limited in order to prevent the tunnel insulating layer from being broken down. That is, it is preferable to suppress the current necessary for the spin torque magnetization reversal from the viewpoint of ensuring the reliability of the memory element 3 against repeated writing. Note that the current required for spin torque magnetization reversal may be referred to as reversal current or recording current.

Further, since the storage device is a non-volatile memory, it is necessary to stably store information written by current. That is, it is necessary to ensure the stability (thermal stability) against the thermal fluctuation of the magnetization of the storage layer.
If the thermal stability of the storage layer is not ensured, the reversed magnetization direction may be reversed again by heat (temperature in the operating environment), resulting in a write error.
The storage element 3 (ST-MRAM) in the present storage device is advantageous in scaling as compared with the conventional MRAM, that is, it is possible to reduce the volume, but the decrease in the volume has the same other characteristics. If it is, it exists in the direction which reduces thermal stability.
When the capacity of the ST-MRAM is increased, the volume of the memory element 3 is further reduced, so ensuring thermal stability becomes an important issue.
Therefore, in the storage element 3 in the ST-MRAM, thermal stability is a very important characteristic, and it is necessary to design the thermal stability to be ensured even if the volume is reduced.

<2. Outline of Memory Element of Embodiment>

Next, an outline of a memory element according to an embodiment of the present disclosure will be described.
In the embodiment of the present disclosure, information is recorded by reversing the magnetization direction of the storage layer of the storage element by the spin torque magnetization reversal described above.
The storage layer is made of a magnetic material including a ferromagnetic layer, and holds information by the magnetization state (magnetization direction) of the magnetic material.
The storage element 3 has, for example, a layer structure shown in FIG. 3, and includes at least two storage layers 17 as ferromagnetic layers and a magnetization fixed layer 15, and an intermediate layer 16 between the two magnetic layers. Prepare.

The storage layer 17 has magnetization perpendicular to the film surface, and the magnetization direction is changed in accordance with information.
The magnetization fixed layer 15 has a magnetization perpendicular to the film surface serving as a reference for information stored in the storage layer 17.
The intermediate layer 16 is an insulating layer made of a nonmagnetic material, for example, and is provided between the storage layer 17 and the magnetization fixed layer 15.
Then, by injecting spin-polarized electrons in the stacking direction of the layer structure including the storage layer 17, the intermediate layer 16, and the magnetization fixed layer 15, the magnetization direction of the storage layer 17 changes, and the storage layer 17 Information is recorded.

Here, the spin torque magnetization reversal will be briefly described.
Electrons have two types of spin angular momentum. This is defined as upward and downward. The number of both is the same inside the non-magnetic material, and the number of both is different inside the ferromagnetic material. In the magnetization fixed layer 15 and the storage layer 17, which are the two layers of ferromagnetic materials constituting the storage element 3, electrons are transferred from the magnetization fixed layer 15 to the storage layer 17 when the directions of the magnetic moments are opposite to each other. Consider the case of moving.

The magnetization fixed layer 15 is a fixed magnetic layer in which the direction of the magnetic moment is fixed for high coercive force.
The electrons that have passed through the magnetization pinned layer 15 have a difference in spin polarization, that is, the upward and downward numbers. If the thickness of the intermediate layer 16 that is a nonmagnetic layer is sufficiently thin, spin polarization due to passage through the magnetization fixed layer 15 is relaxed, and nonpolarization in a normal nonmagnetic material (the same number of upwards and downwards). ) Electrons reach the other magnetic body, that is, the memory layer 17 before the state becomes.
In the memory layer 17, since the signs of the spin polarization are reversed, some electrons are inverted, that is, the direction of the spin angular momentum is changed in order to lower the energy of the system. At this time, since the total angular momentum of the system must be preserved, a reaction equivalent to the sum of changes in angular momentum due to the electrons whose direction is changed is also given to the magnetic moment of the storage layer 17.
When the current, that is, the number of electrons passing through the unit time is small, the total number of electrons changing the direction is small, and therefore the change in the angular momentum generated in the magnetic moment of the storage layer 17 is small. Changes can be given within a unit time.

The time change of the angular momentum is torque, and when the torque exceeds a certain threshold value, the magnetic moment of the storage layer 17 starts precession and becomes stable when rotated 180 degrees due to its uniaxial anisotropy. That is, inversion from the opposite direction state to the same direction state occurs.
When the magnetization is in the same direction state, if a current is flowed in the opposite direction to send electrons from the storage layer 17 to the magnetization fixed layer 15, the electrons that have been spin-reversed when reflected by the magnetization fixed layer 15 are now stored in the storage layer 17. Torque is applied when entering, and the magnetic moment can be reversed to the opposite direction. However, at this time, the amount of current required to cause the reversal is larger than when reversing from the opposite direction state to the same direction state.

Although it is difficult to intuitively understand the reversal of the magnetic moment from the same direction to the opposite direction, the magnetic moment cannot be reversed because the magnetization fixed layer 15 is fixed, and the angular momentum of the entire system is preserved. Therefore, it may be considered that the memory layer 17 is inverted. As described above, recording of 0/1 is performed by flowing a current of a certain threshold value or more corresponding to each polarity in the direction from the fixed magnetization layer 15 to the storage layer 17 or vice versa.
Information is read out by using the magnetoresistive effect as in the conventional MRAM. That is, a current is passed in the direction perpendicular to the film surface as in the case of the above recording. Then, a phenomenon is used in which the electric resistance of the element changes depending on whether the magnetic moment of the storage layer 17 is in the same direction or in the opposite direction to the magnetic moment of the magnetization fixed layer 15.

  The material used for the intermediate layer 16 between the magnetization fixed layer 15 and the storage layer 17 may be a metal or an insulator, but a higher read signal (resistance change rate) can be obtained and recording can be performed with a lower current. This is the case when an insulator is used as the intermediate layer. The element at this time is called a ferromagnetic tunnel junction (Magnetic Tunnel Junction: MTJ).

When the magnetization direction of the magnetic layer is reversed by spin torque magnetization reversal, the required current threshold Ic differs depending on whether the easy axis of magnetization of the magnetic layer is in the in-plane direction or in the vertical direction.
Although the memory element of the present embodiment is a perpendicular magnetization type, if the reversal current for reversing the magnetization direction of the magnetic layer in the case of a conventional in-plane magnetization type memory element is Ic_para,
From the same direction to the opposite direction (Note that the same direction and the reverse direction are the magnetization directions of the storage layer with respect to the magnetization direction of the magnetization fixed layer, and “same direction” and “reverse direction” are “parallel” and “reverse direction”. (Also called “parallel”)
Ic_para = (A · α · Ms · V / g (0) / P) (Hk + 2πMs)
And when reversing from the opposite direction to the same direction,
Ic_para = − (A · α · Ms · V / g (π) / P) (Hk + 2πMs)
It becomes. (The above is assumed to be expression (1).)

On the other hand, when the reversal current of the perpendicular magnetization type storage element as in this example is Ic_perp, when reversing from the same direction to the reverse direction,
Ic_perp = (A · α · Ms · V / g (0) / P) (Hk−4πMs)
And when reversing from the opposite direction to the same direction,
Ic_perp = − (A · α · Ms · V / g (π) / P) (Hk−4πMs)
It becomes. (The above is assumed to be expression (2))

  Where A is a constant, α is a damping constant, Ms is saturation magnetization, V is element volume, P is spin polarizability, g (0) and g (π) are in the same direction and spin torque in the opposite direction. A coefficient Hk corresponding to the efficiency transmitted to the magnetic layer is magnetic anisotropy.

  In each of the above formulas, comparing (Hk−4πMs) in the perpendicular magnetization type and (Hk + 2πMs) in the in-plane magnetization type, it can be understood that the perpendicular magnetization type is more suitable for reducing the recording current.

In the present embodiment, the storage element 3 having a magnetic layer (storage layer 17) capable of holding information depending on the magnetization state and a magnetization fixed layer 15 in which the magnetization direction is fixed is configured.
In order to be able to exist as a memory, it must be able to hold the written information. As an index of the ability to hold information, it is determined by the value of the thermal stability index Δ (= KV / k _B T). This Δ is expressed by the following formula (3).

Δ = K · V / k _B · T = Ms · V · Hk · (1/2 k _B · T) Equation (3)

Here, Hk: effective anisotropy field, k _B: Boltzmann constant, T: temperature, Ms: saturation magnetization, V: volume of storage layer 17, K: is anisotropic energy.
The effect of shape magnetic anisotropy, induced magnetic anisotropy, crystal magnetic anisotropy, etc. is incorporated into the effective anisotropy magnetic field Hk. Equivalent to coercive force.

The thermal stability index Δ and the current threshold value Ic often have a trade-off relationship. Therefore, in order to maintain the memory characteristics, it is often a problem to achieve both.
The threshold value of the current for changing the magnetization state of the storage layer 17 is actually, for example, a threshold value on the + side + Ic in a substantially elliptic TMR element having a thickness of the storage layer 17 of 2 nm and a planar pattern of 100 nm × 150 nm. = + 0.5 mA, −side threshold −Ic = −0.3 mA, and the current density at that time is about 3.5 × 10 ⁶ A / cm ² . These are almost in agreement with the above formula (1).

On the other hand, in a normal MRAM that performs magnetization reversal by a current magnetic field, a write current of several mA or more is required.
Therefore, in the case of the ST-MRAM, it can be understood that the write current threshold is sufficiently small as described above, which is effective in reducing the power consumption of the integrated circuit.
In addition, since a wiring for generating a current magnetic field, which is required in a normal MRAM, is not necessary, the degree of integration is advantageous as compared with a normal MRAM.

When spin torque magnetization reversal is performed, current is directly supplied to the storage element 3 to write (record) information. Therefore, in order to select the storage element 3 to be written, the storage element 3 is selected as a selection transistor. To form a storage device.
In this case, the current flowing through the storage element 3 is limited by the magnitude of the current (saturation current of the selection transistor) that can flow through the selection transistor.
In order to reduce the recording current, it is desirable to adopt the perpendicular magnetization type as described above. Further, since the perpendicular magnetization film can generally have a higher magnetic anisotropy than the in-plane magnetization film, it is preferable in that the above Δ is kept large.

  Magnetic materials having perpendicular anisotropy include rare earth-transition metal alloys (such as TbCoFe), metal multilayer films (such as Co / Pd multilayer films), ordered alloys (such as FePt), and interface anisotropy between oxides and magnetic metals. However, rare earth-transition metal alloys lose their perpendicular magnetic anisotropy when they are diffused and crystallized by heating, and therefore are not preferred as materials for ST-MRAM. In addition, it is known that metal multilayer film diffuses by heating and the perpendicular magnetic anisotropy deteriorates. Further, the perpendicular magnetic anisotropy is manifested in the case of a face-centered cubic (111) orientation. Therefore, it is difficult to realize the (001) orientation required for high polarizability layers such as MgO and Fe, CoFe, CoFeB arranged adjacent to MgO. The L10 ordered alloy is stable even at high temperatures and exhibits perpendicular magnetic anisotropy during (001) orientation, so that the above-mentioned problems do not occur, but it is heated at a sufficiently high temperature of 500 ° C. or higher during production. Alternatively, it is necessary to arrange the atoms regularly by performing a heat treatment at a high temperature of 500 ° C. or higher after manufacture, which may cause undesired diffusion or increase in interface roughness in other portions of the laminated film such as a tunnel barrier.

  On the other hand, a material using interfacial magnetic anisotropy, that is, a material in which a Co-based or Fe-based material is laminated on MgO which is a tunnel barrier is unlikely to cause any of the above problems. Promising as a material.

Further, in consideration of the saturation current value of the selection transistor, a magnetic tunnel junction (MTJ) element using a tunnel insulating layer made of an insulator as the nonmagnetic intermediate layer 16 between the storage layer 17 and the magnetization fixed layer 15. Configure.
By constructing a magnetic tunnel junction (MTJ) element using a tunnel insulating layer, a magnetoresistance change rate (MR ratio) is compared with a case where a giant magnetoresistive effect (GMR) element is constructed using a nonmagnetic conductive layer. This is because the read signal intensity can be increased.

In particular, by using magnesium oxide (MgO) as the material of the intermediate layer 16 as the tunnel insulating layer, the magnetoresistance change rate (MR ratio) can be increased.
In general, the efficiency of the spin transfer depends on the MR ratio, and as the MR ratio increases, the efficiency of the spin transfer improves and the magnetization reversal current density can be reduced.
Therefore, by using magnesium oxide as the material of the tunnel insulating layer and simultaneously using the memory layer 17 described above, the write threshold current due to the spin torque magnetization reversal can be reduced, and information is written (recorded) with a small current. be able to. In addition, the read signal intensity can be increased.

Thereby, the MR ratio (TMR ratio) can be secured, the write threshold current due to the spin torque magnetization reversal can be reduced, and information can be written (recorded) with a small current. In addition, the read signal intensity can be increased.
Thus, when the tunnel insulating layer is formed of a magnesium oxide (MgO) film, it is more desirable that the MgO film is crystallized and the crystal orientation is maintained in the 001 direction.

The area resistance value of the tunnel insulating layer needs to be controlled to about several tens of Ωμm ² or less from the viewpoint of obtaining a current density necessary for reversing the magnetization direction of the memory layer 17 by spin torque magnetization reversal.
In the tunnel insulating layer made of the MgO film, the film thickness of the MgO film needs to be set to 1.5 nm or less in order to make the sheet resistance value in the above range.
In addition, it is desirable to make the storage element 3 small so that the magnetization direction of the storage layer 17 can be easily reversed with a small current.
Therefore, preferably, the area of the memory element 3 is set to 0.01 μm ² or less.

<3. Specific Configuration of Embodiment>

Subsequently, a specific configuration of the embodiment of the present disclosure will be described.
As described above with reference to FIG. 1, the configuration of the storage device is a storage element 3 capable of holding information in a magnetized state near the intersection of two kinds of orthogonal address lines 1 and 6 (for example, a word line and a bit line). Is arranged.
The direction of magnetization of the memory layer 17 can be reversed by spin torque magnetization reversal by passing a current in the vertical direction through the memory element 3 through the two types of address lines 1 and 6.

The drain region 8 is formed in common to the left and right selection transistors in the figure, and a wiring 9 is connected to the drain region 8.
The storage element 3 is disposed between the source region 7 and the other address wiring (for example, bit line) 6 disposed above and extending in the left-right direction in the drawing. The storage element 3 has a storage layer 17 made of a ferromagnetic layer whose magnetization direction is reversed by spin injection.
The storage element 3 is arranged near the intersection of the two types of address lines 1 and 6.
The storage element 3 is connected to the bit line 6 and the source region 7 through upper and lower contact layers 4, respectively.
As a result, a current in the vertical direction can be passed through the storage element 3 through the two types of address lines 1 and 6, and the magnetization direction of the storage layer 17 can be reversed by spin torque magnetization reversal.

FIG. 3 shows a detailed structure of the memory element 3 according to the embodiment of the present disclosure.
As shown in FIG. 3, the storage element 3 is provided with a magnetization fixed layer 15 in a lower layer with respect to the storage layer 17 in which the direction of the magnetization M <b> 17 is reversed by spin torque magnetization reversal.
In the ST-MRAM, 0 or 1 of information is defined by the relative angle between the magnetization M17 of the storage layer 17 and the magnetization M15 of the magnetization fixed layer 15. In this case, those using in-plane magnetization and those using perpendicular magnetization have been developed, but those using in-plane magnetization have a high degree of freedom in materials and a method of fixing magnetization is relatively easy. Has been.
An intermediate layer 16 serving as a tunnel barrier layer (tunnel insulating layer) is provided between the storage layer 17 and the magnetization fixed layer 15, and the storage layer 17 and the magnetization fixed layer 15 constitute an MTJ element.

On the other hand, when a perpendicular magnetization film is used, materials having perpendicular magnetic anisotropy are limited. In recent years, an interface anisotropy type perpendicular magnetization film utilizing perpendicular magnetic anisotropy appearing at a crystal interface between Fe and oxide has been applied. When interface anisotropy is used, a perpendicular magnetization film can be obtained by using an FeCoB alloy as a magnetic material and MgO as an oxide, and both a high magnetoresistance ratio (MR ratio) and perpendicular magnetization can be achieved. It can be applied as a material for the magnetization fixed layer 15.
The magnetization fixed layer 15 and the memory layer 17 are preferably an alloy containing at least one of Fe, Co, and Ni and at least one of B and C, and the content of B and C is 5 atomic% or more and 30 or more. Atomic% or less is preferable.

  An intermediate layer 16 serving as a tunnel barrier layer (tunnel insulating layer) is provided between the storage layer 17 and the magnetization fixed layer 15, and the storage layer 17 and the magnetization fixed layer 15 constitute an MTJ element. For example, MgO is used for the intermediate layer 16.

A magnetic coupling layer 19, a high coercive force layer 20, and an underlayer 14 are formed under the magnetization fixed layer 15, and a cap layer 18 is formed over the storage layer 17.
The reason why the high coercive force layer 20 is provided is to make the coercive force of the magnetization fixed layer 15 larger than the coercive force of the storage layer 17. That is, the coercive force of the magnetization fixed layer 15 is reinforced.
The magnetic coupling layer 19 between the high coercive force layer 20 and the magnetization fixed layer 15 magnetically couples the magnetization fixed layer 15 and the high coercivity layer 20 in antiparallel. This is preferable because the magnetic field on the storage layer 17 is reduced.
The magnetic coupling layer 19 is made of a material such as Ru.

Further, as shown on the right side of FIG. 3, the magnetic coupling layer 19 includes two layers, that is, a magnetic coupling layer 22 and a magnetic coupling layer 21.
The magnetic coupling layer 22 can be made of a material such as Ru. The magnetic coupling layer 21 may be made of any one of Cu, Ag, Au, Ta, Zr, Nb, Hf, W, Mo, Cr, or a plurality of materials. As a result, it is possible to realize the memory element 3 using perpendicular magnetization that can suppress a decrease in the MR ratio and the heat-resistant temperature and can stably operate.

The memory element 3 is formed with a suitable underlayer 14 and a high coercive force layer 20, a magnetic coupling layer 19 such as Ru, a magnetic coupling layer 19 such as Ta, a magnetic pinned layer 15, an intermediate layer 16, a memory The layer 17 and the cap layer 18 are sequentially formed to form a laminated structure. As the underlayer 14, Ta or the like can be used.
As a method for stacking the materials used in the present disclosure, a sputtering method, a vacuum evaporation method, a chemical vapor deposition method (CVD), or the like can be used. Further, in order to control the crystal orientation and the like, a metal film such as Ru or Cr, or a conductive nitride film such as TiN may be formed thereon to form the base layer 14.
As the high coercive force layer 20, an alloy film such as CoPt or FePt, a continuous laminated film of Co and Pt, Co and Pd, or an alloy film such as TbFeCo can be used. A CoPt alloy having heat resistance is suitable.

The magnetic coupling layer 22 is preferably a nonmagnetic metal that mediates strong magnetic coupling such as Ru, Re, Os, and the magnetic coupling layer 21 is Cu, Ag, Au, Ta, Zr, Nb, Hf, W, Mo, Any one or a combination of Cr is preferable.
The thickness of the magnetic coupling layer 21 is preferably 0.05 nm or more and 0.3 nm or less in the case of Ta, Zr, Nb, Hf, W, Mo, or Cr, and 0.1 nm or more and 0.5 nm in the case of Cu, Ag, or Au. The following is preferred. If the thickness of the magnetic coupling layer 21 is less than the specified lower limit of thickness, the effect of improving the MR ratio is small, and if the upper limit of the specified thickness is exceeded, the magnetic coupling strength between the high coercive force layer 20 and the magnetization fixed layer 15 is decreased. Absent.

A stable antiferromagnetic coupling is obtained when the thickness of the magnetic coupling layer 21 is 0.5 nm or more and 0.9 nm or less. As the magnetization fixed layer 15 and the memory layer 17, an alloy containing at least one of Fe, Co, and Ni and at least one of B and C is preferable, and the content of B and C is 5 atomic% to 30 atomic%. The following is preferred.
The storage layer 17 and the magnetization fixed layer 15 preferably contain at least 30% or more Fe in the vicinity of the interface of the intermediate layer 16, and sufficient perpendicular magnetic anisotropy cannot be obtained below that.
As the intermediate layer 16, MgO, Al ₂ O ₃ , TiO ₂ , MgAl ₂ O _{4 and the} like can be used, and using MgO is preferable because the MR ratio is large.
As the cap layer 18, a metal such as Ta or Ti, a conductive nitride such as TiN, or a thin insulating layer such as MgO and a metal film may be used in combination.

In order to configure as a memory device, a CMOS logic circuit is formed on a silicon wafer, the above laminated film is formed on a lower electrode, and then an appropriate method such as reactive ion etching (RIE), ion milling, or chemical etching is used. It is preferable to use it connected to a CMOS circuit so that an appropriate voltage can be applied between the upper electrode and the lower electrode by forming an upper electrode and forming an upper electrode. The shape of the element is arbitrary, but a circular shape is particularly preferable because it is easy to create and can be arranged at high density.
When the perpendicular magnetization film of the present disclosure is applied to a storage device, it has high heat resistance, is easily adaptable to a semiconductor process, has a large magnetoresistance ratio, and can simplify a data reading circuit and increase a reading speed. A storage device can be realized.

  By increasing the MR ratio in this way, the efficiency of spin injection can be improved and the current density required to reverse the direction of the magnetization M17 of the storage layer 17 can be reduced.

In addition, since the thermal stability that is the information retention capability can be sufficiently ensured, the memory element 3 having excellent characteristic balance can be configured.
As a result, an operation error can be eliminated, a sufficient operation margin of the memory element 3 can be obtained, and the memory element 3 can be operated stably.
That is, a highly reliable storage device that operates stably can be realized.
In addition, it is possible to reduce the write current and reduce the power consumption when writing to the memory element 3.

As described above, a highly reliable memory with excellent information retention characteristics and stable operation can be realized, and power consumption can be reduced in the memory including the memory element 3.
Further, the memory device having the memory element 3 shown in FIG. 3 and having the configuration shown in FIG. 1 has an advantage that a general semiconductor MOS formation process can be applied when manufacturing.
Therefore, the memory of this embodiment can be applied as a general-purpose memory.

<4. Experiments on Embodiments>

Here, in order to confirm that the coercive force and the MR ratio of the memory element 3 according to the present embodiment are improved, the magnetic coupling between the magnetization fixed layer 15 and the underlayer 14 in the configuration of the memory element 3 is confirmed. In the case where the layer 19 and the high coercive force layer 20 are provided and the magnetic coupling layer 19 includes two layers, ie, the magnetic coupling layer 22 and the magnetic coupling layer 21, the materials shown in FIGS. It produced and conducted Experiments 1-5, and investigated the magnetic characteristic.

The sample for magnetic property evaluation of this experiment was a Co ₇₀ Pt ₃₀ alloy film as a high coercive force layer 20 with a Ta layer of 5 nm thickness and Ru of 5 nm thickness on a silicon substrate with an oxide coating, As the coupling layer 19, the magnetization fixed layer 15, and the intermediate layer 16, 1 nm of MgO was used, and as the protective film, 1 nm thick Ru and 5 nm thick Ta laminated film were used. The sample for evaluation is for evaluating only the magnetization fixed layer 15 side, and in order to form the memory element 3, it is necessary to insert the memory layer 17 between the MgO of the intermediate layer and the protective film. .

<Experiment 1>
FIG. 4A shows an experiment 1 sample having one magnetic coupling layer.
As shown in FIG. 4A,
-Underlayer 14: Laminated film of Ta film with a thickness of 5 nm and Ru film with a thickness of 5 nm-High coercivity layer 20: Alloy film of Co ₇₀ Pt _{30 with} a thickness of 3 nm-Magnetic coupling layer 19: Ru film (film thickness: tRu)
Magnetization pinned layer 15: laminated film / intermediate layer of 0.5 nm thick Fe ₆₄ Co ₁₆ B ₂₀ alloy film, 0.1 nm thick Ta film and 0.5 nm Fe ₆₄ Co ₁₆ B ₂₀ alloy film 16: Magnesium oxide film / protective film having a film thickness of 1.0 nm: a laminated film of Ru having a film thickness of 1 nm and Ta having a film thickness of 5 nm.
The measurement result of the perpendicular magnetization state by the polar Kerr magneto-optical effect of this sample is shown in FIG. The results after heat treatment at 300 ° C. and the results after heat treatment at 350 ° C. are shown respectively.

FIG. 5 shows the result of the sample in which the Ru thickness tRu was changed. Position shown in figure HC is a magnetic field the magnetization fixed layer 15 and the high coercive force layer 20 is antiparallel to the magnetization reversal while magnetic coupling occurs, H _SF is magnetic coupling between the magnetization fixed layer 15 and the high coercivity layer 20 It is a magnetic field that breaks. In 300 ° C. heat treatment, a change in H _SF point is steep, which indicates that here is inverted and the magnetization fixed layer 15 is effective perpendicular magnetization film.
On the other hand, among the samples after heat treatment at 350 ° C., for example, when tRu is 0.5 nm, the change is gentle. In this case, since the perpendicular magnetization of the magnetization fixed layer 15 is not sufficient, the change of reversal is slow. However, if the magnetic field at which the magnetization reversal of the magnetization fixed layer 15 starts is H _SF , the magnetization fixed layer 15 is perpendicular magnetization below H _SF. It has become.

FIG. 4B shows an experiment 1 sample having two magnetic coupling layers.
As shown in FIG.
-Underlayer 14: Laminated film of 5 nm thick Ta film and 5 nm thick Ru film-High coercive force layer 20: 3 nm thick Co ₇₀ Pt ₃₀ alloy film-Magnetic coupling layer 22: Ru film (thickness: tRu)
Magnetic coupling layer 21: 0.05 nm thick Ta film Magnetized pinned layer 15: 0.5 nm thick Fe ₆₄ Co ₁₆ B ₂₀ alloy film, 0.1 nm thick Ta film and 0.5 nm thick Fe ₆₄ Co ₁₆ B ₂₀ alloy film laminate film / intermediate layer 16: 1.0 nm thick magnesium oxide film / protective film: 1 nm thick Ru and 5 nm thick Ta laminate film.
The measurement result of the perpendicular magnetization state by the polar Kerr magneto-optical effect of this sample is shown in FIG. The results after heat treatment at 300 ° C. and the results after heat treatment at 350 ° C. are shown respectively.
The addition of Ta to the magnetic coupling layer 19, a change in H _SF to the thickness of the Ru magnetic coupling layer 22 as compared with the sample in the case of not adding the aforementioned is smaller as shown in FIG. 6 can be maintained antiparallel The range expands at any temperature.

<Experiment 2>
FIG. 4C shows an experiment 2 sample having two magnetic coupling layers.
As shown in FIG.
-Underlayer 14: Laminated film of 5 nm thick Ta film and 5 nm thick Ru film-High coercive force layer 20: 3 nm thick Co ₇₀ Pt ₃₀ alloy film-Magnetic coupling layer 22: Ru film (thickness: tRu)
Magnetic coupling layer 21: Ta film (film thickness: tTa)
Magnetization fixed layer 15: Fe ₆₄ Co ₁₆ B ₂₀ alloy film with a film thickness of 0.8 nm Intermediate layer 16: Magnesium oxide film with a film thickness of 1.0 nm Protective film: Ru stack with a film thickness of 1 nm and Ta with a film thickness of 5 nm It is a membrane.
It shows the variation of the coupling magnetic field strength H _SF for Ru thickness of the sample of the magnetic coupling layer 22 in FIG.
The results after heat treatment at 300 ° C. and 350 ° C. are shown. When Ta is added to Ru of the magnetic coupling layer, the magnetic coupling layer does not improve the coupling magnetic field strength with the heat treatment at 300 ° C. when compared with the sample of Ru alone. Although it is not so large, it can be confirmed that the heat treatment at 350 ° C. has a high coupling magnetic field strength when Ta is added, and that the addition of Ta is effective in improving the heat resistance.
Further, when the Ru thickness is 0.5 nm to 0.9 nm, the magnetic coupling is difficult to break, and the Ru thickness is preferably 0.5 nm to 0.9 nm.

<Experiment 3>
The sample for Experiment 3 has two magnetic coupling layers, and as shown in FIG.
Underlayer 14: Laminated film of 5 nm thick Ta film and 5 nm thick Ru film High coercivity layer 20: Co ₇₀ Pt ₃₀ alloy film thick 3 nm Magnetic coupling layer 22: 0.6 nm Ru film Magnetic coupling layer 21: A predetermined element is added. Magnetization fixed layer 15: Fe ₆₄ Co ₁₆ B ₂₀ alloy film having a thickness of 0.5 nm, Ta film having a thickness of 0.1 nm, and Fe ₆₄ Co having a thickness of 0.5 nm ₁₆ B ₂₀ alloy film laminated film / intermediate layer 16: magnesium oxide film with a film thickness of 1.0 nm / protective film: Ru film with a film thickness of 1 nm and Ta film with a film thickness of 5 nm.
This sample is used to investigate the difference in characteristics when Ta is added to Ru of the magnetic coupling layer and when an element other than Ta is added.
It shows the thickness dependence of the additional layer of coupling field strength H _SF after heat treatment of the present sample at 300 ° C. Figure 8. As elements to be added, Ta, Cr, Mg, Si, W, Nb, Zr, Hf, and Mo are shown. Similarly, FIG. 9 shows the result after heat treatment at 350 ° C. When the additional element is Ta, Cr, W, Nb, Zr, Hf, or Mo, the coupling magnetic field strength is improved. In particular, Ta has a large improvement effect after 350 ° C. heat treatment.
The film thickness where improvement is seen is 0.05 nm or more and 0.3 nm or less.

<Experiment 4>
The sample for Experiment 4 has two magnetic coupling layers, and as shown in FIG.
Underlayer 14: Laminated film of 5 nm thick Ta film and 5 nm thick Ru film High coercive force layer 20: Co ₇₀ Pt ₃₀ alloy film thick 3 nm Magnetic coupling layer 22: 0.8 nm Ru film Magnetic coupling layer 21: A predetermined element is added. Magnetization fixed layer 15: Fe ₆₄ Co ₁₆ B ₂₀ alloy film having a thickness of 0.8 nm, Ta film having a thickness of 0.3 nm, and Fe ₆₄ Co having a thickness of 0.8 nm. ₁₆ B ₂₀ alloy film laminated film / intermediate layer 16: magnesium oxide film with a film thickness of 1.0 nm / protective film: Ru film with a film thickness of 1 nm and Ta film with a film thickness of 5 nm.
This sample is to investigate the difference in characteristics when Cu, Ag, and Au elements are added to Ru of the magnetic coupling layer.
FIG. 10 shows the dependence of the combined magnetic field strength _{HSF on} the added layer thickness of the sample heat-treated at 300 ° C. and 350 ° C. Similar to the result of Experiment 3, in any case of Cu, Ag, and Au, the effect of improving the coupling magnetic field strength is observed. With these elements, the thickness at which the coupling magnetic field strength is improved is 0.1 nm or more and 0.5 nm or less.

<Experiment 5>
Experiment 5 is to create a memory element having a memory layer and measure the magnetoresistance ratio (MR ratio).
The sample for Experiment 5 is shown in FIG. As shown in FIG. 11, five types of samples were prepared.
(1) Sample with one magnetic coupling layer: Underlayer 14: Laminated film of Ta film with a thickness of 5 nm and Ru film with a thickness of 5 nm, high coercive force layer 20: CoPt alloy film with a thickness of 2 nm, magnetic coupling layer 19: 0.8 nm thick Ru film / magnetization pinned layer 15: 0.8 nm thick Fe ₆₄ Co ₁₆ B ₂₀ alloy film / intermediate layer 16: 1.0 nm thick magnesium oxide film / memory layer 17: 1 thick film .4 nm Fe ₆₄ Co ₁₆ B ₂₀ alloy film / protective film: 5 nm thick Ta film (2) Sample 1 with two magnetic coupling layers
-Underlayer 14: Laminated film of Ta film with a thickness of 5 nm and Ru film with a thickness of 5 nm-High coercivity layer 20: Alloy film of CoPt with a thickness of 2 nm-Magnetic coupling layer 22: Ru film with a thickness of 0.6 nm-Magnetic coupling Layer 21: 0.1 nm thick Ta film, magnetization fixed layer 15: Fe ₆₄ Co ₁₆ B ₂₀ alloy film with 0.8 nm thickness, intermediate layer 16: Magnesium oxide film with 1.0 nm thickness, memory layer 17: Film thickness 1.4 nm Fe ₆₄ Co ₁₆ B ₂₀ alloy film / protective film: 5 nm thick Ta film (3) Sample 2 with two magnetic coupling layers
-Underlayer 14: Laminated film of Ta film with a thickness of 5 nm and Ru film with a thickness of 5 nm-High coercivity layer 20: Alloy film of CoPt with a thickness of 2 nm-Magnetic coupling layer 22: Ru film with a thickness of 0.6 nm-Magnetic coupling Layer 21: 0.1 nm thick Ta film, magnetization fixed layer 15: 1.2 nm thick Fe ₆₄ Co ₁₆ B ₂₀ alloy film, intermediate layer 16: 1.0 nm thick magnesium oxide film, memory layer 17: thick film 1.4 nm Fe ₆₄ Co ₁₆ B ₂₀ alloy film / protective film: 5 nm thick Ta film (4) Sample 3 with two magnetic coupling layers
-Underlayer 14: Laminated film of Ta film with a thickness of 5 nm and Ru film with a thickness of 5 nm-High coercivity layer 20: CoPt alloy film with a thickness of 2 nm-Magnetic coupling layer 22: Re film with a thickness of 0.7 nm-Magnetic coupling Layer 21: 0.1 nm thick Ta film, magnetization fixed layer 15: Fe ₆₄ Co ₁₆ B ₂₀ alloy film with 0.8 nm thickness, intermediate layer 16: Magnesium oxide film with 1.0 nm thickness, memory layer 17: Film thickness 1.2 nm Fe ₆₀ Ni ₃₀ C ₁₀ alloy film / protective film: 5 nm thick Ta film (5) Sample 4 with two magnetic coupling layers
Underlayer 14: Laminated film of 5 nm thick Ta film and 5 nm thick TiN film High coercivity layer 20: 2 nm thick FePt alloy film Magnetic coupling layer 22: 0.8 nm thick Os film Magnetic coupling Layer 21: 0.05 nm thick Ta film, magnetization fixed layer 15: 1.0 nm thick Fe ₅₀ Co ₁₀ Cr ₂₀ B ₂₀ alloy film, intermediate layer 16: 1.0 nm thick magnesium oxide film, memory layer 17: Fe ₆₄ Co ₁₆ B ₂₀ alloy film with 1.5 nm thickness and protective film: Ta film with 5 nm thickness

  Table 1 shows the MR ratio measurement results of the samples subjected to heat treatment at 300 ° C. and 350 ° C. In the memory element according to the present embodiment, the MR ratio is greatly improved particularly in the heat treatment at 350 ° C., and it can be seen that the technique of the present disclosure is highly effective in improving the heat resistance and the MR ratio.

  Although the embodiments have been described above, the present disclosure is not limited to the film configuration of the memory element 3 described in each of the above-described embodiments, and various film configurations can be employed.

For example, in the embodiment, the magnetization fixed layer 15 is made of CoFeB. However, the present invention is not limited to the embodiment, and various other configurations are possible without departing from the gist of the present disclosure.
Further, in the embodiments, only a single base is shown, but the present invention is not limited thereto, and various other configurations can be taken without departing from the gist of the present disclosure.
In the embodiment, the pinned magnetization layer 15 has a laminated ferripin structure including two ferromagnetic layers and a nonmagnetic layer, but may have a structure in which an antiferromagnetic film is added to the laminated ferripin structure film.
Of course, it may be a single layer.
In addition, the film configuration of the storage element 3 has no problem whether the storage layer 17 is disposed above the fixed magnetization layer 15 or the lower layer.

In addition, this technique can also take the following structures.
(1) a storage layer that holds information according to the magnetization state of the magnetic material;
A magnetization fixed layer having a magnetization serving as a reference for information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A magnetic coupling layer provided adjacent to the magnetization fixed layer and on the opposite side of the intermediate layer;
A high coercivity layer provided adjacent to the magnetic coupling layer,
Information is stored by reversing the magnetization of the storage layer by utilizing the spin torque magnetization reversal that occurs with the current flowing in the stacking direction of the layer structure having the storage layer, the intermediate layer, and the magnetization fixed layer. With
A memory element in which the magnetic coupling layer has a laminated structure of two layers.
(2) The memory layer and the magnetization fixed layer contain at least one of Fe, Co, and Ni as a main component, and include any one of B and C of 5 atomic% to 30 atomic%. The memory element according to (1) above.
(3) Of the two magnetic coupling layers,
The memory element according to (1) or (2), wherein the layer on the high coercive force layer side is made of at least one of Ru, Re, and Os.
(4) Of the two magnetic coupling layers,
The memory element according to any one of (1) to (3), wherein the layer on the magnetization fixed layer side is made of at least one of Cu, Ag, Au, Ta, Zr, Nb, Hf, W, Mo, and Cr.
(5) Of the two magnetic coupling layers,
Any of (1) to (3), wherein the layer on the magnetization fixed layer side is made of at least one of Ta, Zr, Nb, Hf, W, Mo, and Cr, and the layer thickness is 0.05 nm to 0.3 nm. The memory element described in 1.
(6) Of the two magnetic coupling layers,
The layer on the magnetization fixed layer side is made of at least one of Cu, Ag, Au,
The memory element according to any one of (1) to (3), wherein the layer thickness is 0.1 nm to 0.5 nm. (7) The memory element according to any one of (1) to (6), wherein the layer thickness on the high coercive force layer side is 0.5 nm to 0.9 nm.

  DESCRIPTION OF SYMBOLS 1 Gate electrode, 2 Element separation layer, 3 Memory element, 4 Contact layer, 6 Bit line, 7 Source region, 8 Drain region, 9 Wiring, 10 Semiconductor substrate, 14 Underlayer, 15 Magnetization fixed layer, 16 Intermediate layer, 17 Memory layer, 18 cap layer, 19 21 22 Magnetic coupling layer 20 High coercive force layer

A spin transfer torque memory element of the present disclosure includes a first portion having CoFeB, a second portion having CoFeB, an intermediate portion having a MgO position between the first portion and the second portion, Adjacent to the second part, provided on the opposite side of the intermediate part, including at least one of Ag, Au, Cr, Cu, Hf, Mo, Nb, Os, Re, Ru, Ta, W, Zr A third portion; and a fourth portion adjacent to the third portion and provided on the opposite side of the second portion and including an alloy of at least one of Co, Fe, Pd, and Pt.

The storage device of the present disclosure includes a spin transfer torque storage element that retains information according to the magnetization state of a magnetic material, and two types of wirings that intersect each other, and the spin transfer torque storage element includes a first portion having CoFeB, A second portion having CoFeB, an intermediate portion having MgO located between the first portion and the second portion, adjacent to the second portion, and provided on the opposite side of the intermediate portion; A third portion including at least one of Ag, Au, Cr, Cu, Hf, Mo, Nb, Os, Re, Ru, Ta, W, and Zr; and the second portion adjacent to the third portion and the second portion provided on the opposite side, Co, Fe, Pd, at least one of the two types include a fourth portion, a containing alloy of the spin transfer torque memory element during the wiring of Pt are arranged, the Through type of wiring, the spin transfer torque memory element above the stacking direction of the current flows through the spin torque magnetization reversal occurs accordingly.

Claims (4)

A storage layer that holds information by the magnetization state of the magnetic material;
A magnetization fixed layer having a magnetization serving as a reference for information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A magnetic coupling layer provided adjacent to the magnetization fixed layer and on the opposite side of the intermediate layer;
A high coercivity layer provided adjacent to the magnetic coupling layer,
Information is stored by reversing the magnetization of the storage layer by utilizing the spin torque magnetization reversal that occurs with the current flowing in the stacking direction of the layer structure having the storage layer, the intermediate layer, and the magnetization fixed layer. With
The magnetic coupling layer has a laminated structure of two layers,
Of the two layers of the magnetic coupling layer,
The layer on the high coercive force layer side is made of at least one of Ru, Re, and Os.
Of the two layers of the magnetic coupling layer,
The layer on the magnetization fixed layer side is made of at least one of Cu, Ag, Au,
The memory element, wherein the layer thickness is 0.1 nm to 0.5 nm.   2. The storage layer and the magnetization fixed layer contain at least one of Fe, Co, and Ni as a main component, and include any one of B and C of 5 atomic% to 30 atomic%. The memory element described in 1. Of the two layers of the magnetic coupling layer,
The memory element according to claim 1, wherein the layer thickness on the high coercive force layer side is 0.5 nm to 0.9 nm. A storage element that holds information according to the magnetization state of the magnetic material;
Two types of wiring intersecting each other,
The memory element is
A storage layer that retains information in accordance with the magnetization state of the magnetic material, a magnetization fixed layer that has a magnetization serving as a reference for information stored in the storage layer, and a nonmagnetic material provided between the storage layer and the magnetization fixed layer A magnetic coupling layer provided on the opposite side of the intermediate layer, and a high coercivity layer provided adjacent to the magnetic coupling layer, the storage layer, Information storage is performed by reversing the magnetization of the storage layer by utilizing the spin torque magnetization reversal that occurs in accordance with the current flowing in the stacking direction of the layer structure having the intermediate layer and the magnetization fixed layer, and the magnetic coupling The layer has a laminated structure of two layers,
Of the two layers of the magnetic coupling layer,
The layer on the high coercive force layer side is made of at least one of Ru, Re, and Os.
Of the two layers of the magnetic coupling layer,
The layer on the magnetization fixed layer side is made of at least one of Cu, Ag, Au,
The layer thickness is 0.1 nm to 0.5 nm, and the memory element is disposed between the two types of wirings.
A memory device in which a current in the stacking direction flows in the memory element through the two types of wirings, and accordingly, spin torque magnetization reversal occurs.

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