JP2017212464A - Storage element, storage device, and magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance operation stability while achieving reduction in size of an element.SOLUTION: A storage element includes a layered structure having: a storage layer which has magnetization that is perpendicular to a film surface and in which a direction of the magnetization changes according to information; a fixed magnetization layer which has magnetization that is perpendicular to the film surface and functions as a reference for the information stored in the storage layer; and a middle layer disposed between the storage layer and the fixed magnetization layer and formed from a non-magnetic body. By injecting spin-polarized electrons in a lamination direction of the layered structure, a direction of the magnetization of the storage layer changes, and thereby information is stored. In this case, the fixed magnetization layer has a layered ferri-structure comprising at least two ferromagnetic layers and a non-magnetic layer. Alloy using Pt and Co or Y-containing magnetic material with a layered structure is used as magnetic material in the fixed magnetization layer.SELECTED DRAWING: Figure 5

Description

  The present technology relates to a storage element and a storage device that have a plurality of magnetic layers and perform storage using spin torque magnetization reversal. The present invention also relates to a magnetic head for detecting a magnetic signal from a magnetic recording medium.

JP 2003-17782 A US Pat. No. 6,256,223 JP 2008-227388 A JP 2010-80746 A

Phys. Rev. B, 54, 9353 (1996) J. Magn. Mat., 159, L1 (1996) Nature Materials., 5, 210 (2006) Phys. Rev. Lett., 67, 3598 (1991)

Along with the dramatic development of various information devices from mobile terminals to large-capacity servers, even higher performance such as higher integration, higher speed, lower power consumption, etc. in the elements such as memory and logic Is being pursued. In particular, the progress of semiconductor non-volatile memories is remarkable, and in particular, flash memories as large-capacity file memories are becoming widespread at the moment of expelling hard disk drives.
On the other hand, development of semiconductor non-volatile memories is being promoted in order to replace NOR flash memories, DRAMs, and the like that are generally used at present, in view of development for code storage and further working memories. For example, FeRAM (Ferroelectric Random Access Memory), MRAM (Magnetic Random Access Memory), PCRAM (phase change RAM), etc. are mentioned. Some of these are already in practical use.

Among these non-volatile memories, MRAM stores data according to the magnetization direction of the magnetic material, so it can be rewritten at high speed and can be rewritten almost infinitely (over 10 ¹⁵ times). It is used in such fields.
MRAM is expected to expand to code storage and working memory in the future because of its high-speed operation and reliability.

However, MRAM has problems in reducing power consumption and capacity.
This is an essential problem due to the memory principle of MRAM, that is, the method of reversing the magnetization by the current magnetic field generated from the wiring.
As one method for solving this problem, a storage (ie, magnetization reversal) method that does not rely on a current magnetic field has been studied, and research on spin torque magnetization reversal is particularly active (for example, Patent Documents 1 and 2). 3, Non-Patent Documents 1 and 2).
Hereinafter, the MRAM using spin torque magnetization reversal is referred to as STT-MRAM (Spin Torque Transfer based Magnetic Random Access Memory). The spin torque magnetization reversal may also be called spin injection magnetization reversal.

There are two types of STT-MRAM: in-plane and perpendicular magnetization. Among them, in recent years, a perpendicular magnetization type STT-MRAM more suitable for scaling has been actively developed.
For example, Non-Patent Document 3 suggests that the use of a perpendicular magnetization film such as a Co / Ni multilayer film for the storage layer can achieve both reduction of reversal current and securing of thermal stability.

Storage elements in STT-MRAM are advantageous in scaling compared to conventional MRAM. That is, the volume of the memory layer can be reduced. However, the reduction in volume generally reduces the thermal stability of the magnetic material, which leads to memory operation failure.
Therefore, it is important to increase the stability of memory operation in a fine device in order to reduce the element size (and consequently increase the memory capacity).

  Therefore, the present technology aims to reduce a write error caused by spin torque fluctuation in a storage element as an STT-MRAM and to improve the stability of information write operation of a memory in a fine device.

First, the storage element according to the present technology has a magnetization perpendicular to the film surface, the magnetization direction of which changes according to information, and a reference for information stored in the storage layer A layer structure having a magnetization fixed layer having magnetization perpendicular to the film surface, and an intermediate layer made of a nonmagnetic material provided between the storage layer and the magnetization fixed layer, and spin-polarized in the stacking direction of the layer structure. By injecting polarized electrons, the magnetization direction of the storage layer changes, and information is stored in the storage layer. The magnetization fixed layer has a laminated ferrimagnetic structure composed of at least two ferromagnetic layers and a nonmagnetic layer, and an alloy or a laminated structure using Pt and Co as magnetic materials in the magnetization fixed layer. In this case, a magnetic material containing Y is used.
That is, by using a magnetization fixed layer having a laminated ferrimagnetic structure having a large coupling magnetic field in the STT-MRAM memory element, a write error due to spin torque fluctuation is reduced. The reason why the coupling magnetic field of the laminated ferrimagnetic structure can be increased by adding Y as compared with the case of using only Co—Pt is, for example, that Y becomes Co—Y and the perpendicular magnetic anisotropy due to Co—Y appears. It is possible that
Second, in the memory element according to the present technology described above, an alloy or a stacked structure using Pt and Co is used as a magnetic material that does not contact the intermediate layer in the magnetization fixed layer, and includes Y. Magnetic material is used.
Third, in the memory element according to the above-described present technology, it is preferable that the amount of addition of the Y element is 12 at% (atomic percentage) or less.
In the above-described laminated ferripin structure, a higher coupling magnetic field can be obtained when Y is added in the range of 12 at% or less than when Y is not added.
Fourth, in the memory element according to the present technology described above, it is desirable that the amount of addition of the Y element is 1 at% or more and 10 at% or less.
In the above laminated ferripin structure, a higher coupling magnetic field and a preferable resistance change rate can be obtained when the Y addition amount is in the range of 1 to 10 at%.
Fifth, in the memory element according to the present technology described above, it is desirable that the magnetic material in contact with the intermediate layer in the magnetization fixed layer is formed of a CoFeB magnetic layer.

In addition, the memory element according to the present technology has a magnetization perpendicular to the film surface, the direction of the magnetization being changed corresponding to information, and a film surface serving as a reference for information stored in the memory layer. An electron having a layer structure having a magnetization fixed layer having perpendicular magnetization and a nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer, and spin-polarized electrons in the stacking direction of the layer structure Is injected to change the magnetization direction of the storage layer, and information is stored in the storage layer, and an alloy using Pt and Co as a magnetic material in the fixed magnetization layer or A magnetic material having a laminated structure and containing Y is used.
Also in this case, the addition amount of the Y element is desirably 12 at% or less, and more desirably, the addition amount of the Y element is 1 at% or more and 10 at% or less.

A storage device according to the present technology includes a storage element that holds information according to the magnetization state of a magnetic material, and two types of wirings that intersect each other. The memory element has the above-described configuration, the memory element is disposed between the two types of wirings, and the current in the stacking direction flows through the memory elements through the two types of wirings to cause spin polarization. Electrons are injected.
The magnetic head according to the present technology is a magnetic head having a configuration similar to that of the storage element described above.

According to the present technology, by increasing the coupling magnetic field of the laminated ferripin structure of the magnetization fixed layer, the write error due to the spin torque fluctuation is reduced without sacrificing the resistance change rate, thereby writing the information in the memory in the micro device. The stability of operation can be improved.
Further, according to the magnetic head of the present technology to which the structure of the storage element of the present technology is applied, a highly reliable magnetic head having excellent thermal stability can be realized.
Note that the effects described here are not necessarily limited, and may be any of the effects described in the present disclosure.

It is a schematic perspective view of the memory | storage device of embodiment. It is sectional drawing of the memory | storage device of embodiment. It is a top view of the memory | storage device of embodiment. It is explanatory drawing of the structure of the memory element of embodiment. It is explanatory drawing of the structure of the sample used in Experiment 1. FIG. It is explanatory drawing of the structure of the sample used in Experiment 2. FIG. It is explanatory drawing of the coupling magnetic field and resistance change rate of the laminated ferri pin structure obtained from the VSM measurement result about each sample of Experiment 1,2. It is explanatory drawing of the structure of the magnetization fixed layer of the memory | storage element of embodiment as a modification. It is explanatory drawing of the example of application to the composite type magnetic head of embodiment. It is explanatory drawing of a structure of the memory | storage element of embodiment as a modification.

Hereinafter, embodiments will be described in the following order.
<1. Configuration of Storage Device of Embodiment>
<2. Configuration of Memory Element of Embodiment>
<3. Experimental results>
<4. Modification>

<1. Configuration of Storage Device of Embodiment>
First, a schematic configuration of the storage device will be described.
Schematic diagrams of the storage device are shown in FIGS. 1 is a perspective view, FIG. 2 is a cross-sectional view, and FIG. 3 is a plan view.

As shown in FIG. 1, the storage device according to the embodiment is an STT-MRAM that can hold information in the state of magnetization near the intersection of two types of address lines (for example, a word line and a bit line) orthogonal to each other. The storage element 3 is formed by (Spin Transfer Torque based Magnetic Random Access Memory).
That is, the drain region 8, the source region 7, and the gate electrode 1 constituting a selection transistor for selecting each storage element 3 are formed in a portion separated by the element isolation layer 2 of the semiconductor substrate 10 such as a silicon substrate. , Each is formed. Of these, the gate electrode 1 also serves as one address wiring (word line) extending in the front-rear direction in the figure.

The drain region 8 is formed in common to the left and right selection transistors in FIG. 1, 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).

In the memory element 3 as an STT-MRAM using the MTJ element of the present embodiment, spin-polarized electrons passing through a magnetic layer fixed in a certain direction are transferred to another free magnetic layer (the direction is not fixed). This uses the application of torque to the magnetic layer when entering (this is also referred to as spin torque). When a current exceeding a certain threshold is passed, the free magnetic layer is inverted. 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.
Such an STT-MRAM is suitable as a non-volatile memory that can achieve low power consumption and large capacity while maintaining the advantage of MRAM that is high speed and the number of rewrites is almost infinite.

As shown in FIG. 2, the memory element 3 has two magnetic layers 12 and 14. Of these two magnetic layers 12, 14, one magnetic layer is a fixed magnetization layer 12 in which the direction of magnetization M12 is fixed, and the other magnetic layer is a free magnetic layer, that is, a storage layer 14 in which the direction of magnetization M14 changes. And
The storage element 3 is connected to the bit line 6 and the source region 7 via upper and lower contact layers 4, respectively.
As a result, a current in the vertical direction (stacking direction) can be passed through the memory element 3 through the two types of address wirings 1 and 6, and the direction of the magnetization M14 of the memory layer 14 can be reversed by spin torque magnetization reversal.

As shown in FIG. 3, the storage device has storage elements 3 arranged at the intersections of a large number of first wirings (word lines) 1 and second wirings (bit lines) 6 arranged in a matrix. It is configured.
The memory element 3 has a circular planar shape as an example, and has the cross-sectional structure shown in FIG.
Further, the storage element 3 includes a fixed magnetization layer 12 and a storage layer 14 as shown in FIG.
Each memory element 3 constitutes a memory cell of the memory device.

  Here, 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. In order to achieve this, it is preferable to improve the spin torque transmission efficiency 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 this purpose, the above-described MTJ structure is employed, that is, an intermediate between the two magnetic layers 12 and 14. It is effective to adopt a configuration of the memory element 3 in which the layer is a tunnel insulating layer (tunnel barrier layer).
The advantage of adopting the MTJ structure is that a large magnetoresistive change rate can be secured and the read signal can be increased.

  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 is also called reversal current, storage current, and the like.

  There are two types of STT-MRAM, in-plane and perpendicular magnetization. In this embodiment, a perpendicular magnetization type STT-MRAM that is more suitable for scaling is used. Use of the perpendicular magnetization film for the memory layer 14 is advantageous in reducing both reversal current and ensuring thermal stability.

The storage element 3 (STT-MRAM) in the present storage device is advantageous in scaling as compared with the conventional MRAM, that is, the volume can be reduced, but the decrease in the volume means the thermal stability of magnetization. Is in the direction of lowering.
When the capacity of the STT-MRAM is increased, the volume of the storage element 3 is further reduced, so that it is important to ensure the stability of the memory operation.

<2. Configuration of Memory Element of Embodiment>
Next, the configuration of the memory element 3 of the embodiment will be described with reference to FIG.
As shown in FIG. 4A, the memory element 3 includes a magnetization fixed layer (also referred to as a reference layer) 12 and an intermediate layer (nonmagnetic layer: tunnel insulating layer) 13 in which the direction of the magnetization M12 is fixed on the base layer 11. A storage layer (free magnetization layer) 14 in which the direction of the magnetization M14 is variable and a cap layer 15 are laminated in the same order.

The memory layer 14 has a magnetization M14 perpendicular to the film surface, and the magnetization direction is changed corresponding to information.
The magnetization fixed layer 12 has a magnetization M12 perpendicular to the film surface, which serves as a reference for information stored in the storage layer. In the magnetization fixed layer 12, the direction of the magnetization M12 is fixed by a high coercive force or the like.
The intermediate layer 13 is a nonmagnetic material and is provided between the storage layer 14 and the magnetization fixed layer 12.
Then, by injecting spin-polarized electrons in the stacking direction of the layer structure including the memory layer 14, the intermediate layer 13, and the magnetization fixed layer 12, the magnetization direction of the memory layer 14 changes, and the memory layer 14 is changed. Information is stored.
The underlayer 11 and the cap layer 15 are used as electrodes and also function as a protective layer.

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 12 and the storage layer 14 that are two-layered ferromagnetic materials constituting the STT-MRAM, electrons are stored from the magnetization fixed layer 12 when the directions of the magnetic moments are in the opposite directions (anti-parallel). Consider the case of moving to the layer 14.

The magnetization fixed layer 12 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 fixed layer 12 have a difference in spin polarization, that is, the upward and downward numbers. If the thickness of the intermediate layer 13 which is a nonmagnetic layer is sufficiently thin, spin polarization due to the passage of the magnetization fixed layer 12 is relaxed, and nonpolarization in a normal nonmagnetic material (the same number of upwards and downwards). ) Before reaching the state, electrons reach the other magnetic body, that is, the memory layer 14.
In the memory layer 14, the sign of the spin polarization is reversed, so that 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 14.

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, so that the change in angular momentum generated in the magnetic moment of the storage layer 14 is small. The momentum change 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 14 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 (parallel) state occurs.

  When the magnetization is in the same direction state, if a current is flown in the opposite direction to send electrons from the storage layer 14 to the fixed magnetization layer 12, then the electrons that are spin-reversed when reflected by the fixed magnetization layer 12 are stored in the storage layer 14. 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 12 is fixed, and the angular momentum of the entire system is preserved. Therefore, it may be considered that the memory layer 14 is inverted.

  As described above, the storage 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 magnetization fixed layer 12 to the storage layer 14 or in the opposite direction.

  On the other hand, reading of information is performed 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 memory described above. Then, a phenomenon is used in which the electric resistance of the element changes depending on whether the magnetic moment of the storage layer 14 is in the same direction or in the opposite direction to the magnetic moment of the magnetization fixed layer 12.

  The material used for the intermediate layer 13 between the magnetization fixed layer 12 and the storage layer 14 may be a metal or an insulator, but a higher read signal (rate of change in resistance) can be obtained and storage can be performed with a lower current. It is assumed that an insulator is used as the intermediate layer. The element at this time is called a ferromagnetic tunnel junction (Magnetic Tunnel Junction: MTJ).

  In the case of a perpendicular magnetization type memory element, the current threshold Ic required when the magnetization direction of the magnetic layer is reversed by spin torque magnetization reversal is expressed by the following [Equation 1].

Where e is the charge of the electron, η is the spin injection efficiency, h with a bar is the conversion plank constant, α is the damping constant, k _B is the Boltzmann constant, and T is the temperature.

Here, in order to exist as a memory, it is necessary to be able to hold information written in the storage layer 14. The ability to retain information is determined by the value of the thermal stability index Δ (= KV / k _B T). This Δ is expressed by the following [Equation 2].

Here, K: anisotropy energy, Hk: effective anisotropy magnetic field, k _B : Boltzmann constant, T: temperature, Ms: saturation magnetization, V: volume of storage layer.
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.

  In many cases, the thermal stability index Δ and the current threshold value Ic basically have a trade-off relationship. Therefore, in order to maintain the memory characteristics, both of these are problems.

Here, in the case of performing spin torque magnetization reversal, information is written (stored) by directly passing a current through the memory element 3, so that the memory element 3 is selected as a selection transistor in order to select a memory cell to be written. To form a memory cell.
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 storage 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.

Perpendicular magnetization magnetic materials include rare earth-transition metal alloys (such as TbCoFe), metal multilayer films (such as Co / Pd multilayer films), ordered alloys (such as FePt), and utilization of interface anisotropy between oxides and magnetic metals ( There are several types such as Co / MgO). 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 STT-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 as a tunnel barrier is unlikely to cause any of the above problems, and therefore, the storage layer of STT-MRAM. Promising as a material.

  On the other hand, it is also promising that a perpendicular magnetization magnetic material having interface magnetic anisotropy is used for the magnetization fixed layer 12. In particular, in order to give a large read signal, a magnetic material containing Co or Fe laminated under MgO as a tunnel barrier is promising.

In the present embodiment, the storage layer 14 is a CoFeB perpendicular magnetization film.
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 13 between the storage layer 14 and the magnetization fixed layer 12. 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. ) Can be increased, and the read signal intensity can be increased.
In particular, by using magnesium oxide (MgO) as the material of the intermediate layer 13 as the tunnel insulating layer, the magnetoresistance change rate (MR ratio) can be increased.
In general, the transmission efficiency of the spin torque depends on the MR ratio, and the larger the MR ratio, the higher the transmission efficiency of the spin torque and the lower the magnetization reversal current density.
Therefore, by using magnesium oxide as the material of the tunnel insulating layer and simultaneously using the memory layer 14 described above, the write threshold current due to the spin torque magnetization reversal can be reduced, and information is written (stored) with a small current. be able to. In addition, the read signal intensity can be increased.
Thereby, the MR ratio (TMR ratio) can be ensured, the write threshold current due to the spin torque magnetization reversal can be reduced, and information can be written (stored) 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.
In the present embodiment, the intermediate layer 13 between the storage layer 14 and the magnetization fixed layer 12 is made of magnesium oxide as described above, for example, aluminum oxide, aluminum nitride, SiO ₂ , Bi ₂ O ₃ , MgF ₂ , CaF, SrTiO ₂ , AlLaO ₃ , Al—N—O and other various insulators, dielectrics, and semiconductors can also be used.

The sheet resistance value of the intermediate layer (tunnel insulating layer) 13 is controlled to be 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 14 by spin torque magnetization reversal. Is desirable.
In the tunnel insulating layer made of the MgO film, it is desirable to set the film thickness of the MgO film to 1.5 nm or less in order to make the sheet resistance value in the above range.

In the storage element 3 of the present embodiment, the cap layer 15 is disposed adjacent to the storage layer 14.
The cap layer 15 is made of an oxide.
The oxide cap layer 15, for example MgO, aluminum _{oxide, TiO 2, SiO 2, Bi} 2 O 3, SrTiO 2, AlLaO 3, using the Al-N-O, and the like.

Here, in the memory element 3, a single layer structure may be adopted as the structure of the magnetization fixed layer 12, but it is effective to adopt a laminated ferripin structure composed of two or more ferromagnetic layers and a nonmagnetic layer. is there. This is because the asymmetry of the thermal stability with respect to the information writing direction can be easily canceled and the stability against spin torque can be improved by making the magnetization fixed layer 12 have a laminated ferri-pin structure.
Therefore, also in this embodiment, the magnetization fixed layer 12 has a laminated ferripin structure. That is, for example, as shown in FIG. 4B, the magnetization fixed layer 12 has a laminated ferripin structure including at least two ferromagnetic layers 12a and 12c and a nonmagnetic layer 12b.

In the embodiment, among the magnetic materials in the magnetization fixed layer 12, the magnetic material as the ferromagnetic layer 12c not in contact with the intermediate layer 13 is an alloy or a laminated structure using Pt (platinum) and Co (cobalt). And Y (yttrium) is added.
As a result, the coupling magnetic field of the laminated ferripin structure can be increased as compared with the case of using only Co—Pt as the ferromagnetic layer 12c, and the information writing operation of the memory can be stabilized without impairing the resistance change rate.

Here, the reason for paying attention to Y as an additive material to Co—Pt is as follows.
In the present embodiment, one of the reasons for selecting Co—Pt as the magnetic material of the ferromagnetic layer 12c not in contact with the intermediate layer 13 in the magnetization fixed layer 12 is to have high perpendicular magnetic anisotropy energy relatively easily. It is mentioned that a thin film can be created.
On the other hand, Co-rare earth system [Y, lanthanoid] exists as a material having high perpendicular magnetic anisotropy energy.
The origin of high perpendicular magnetic anisotropy energy in Co-Pt and Co-rare earth materials is thought to be different, but among the rare earth materials, Y is the closest to Co in terms of the periodic table. If there is, it can be estimated that high perpendicular magnetic anisotropy attributable to the Co-rare earth system can be imparted without disturbing the state of Co that exhibits high perpendicular magnetic anisotropy in Co-Pt.

From this point, in the memory element 3 of the present embodiment, the magnetization fixed layer 12 is configured as follows.
That is, the magnetization fixed layer 12 has a laminated ferripin structure including at least two ferromagnetic layers 12a and 12c and a nonmagnetic layer 12b.
Of the magnetic material in the magnetization fixed layer 12, the magnetic material of the ferromagnetic layer 12a in contact with the intermediate layer 13 is CoFeB.
The magnetic material of the ferromagnetic layer 12c not in contact with the intermediate layer 13 is an alloy or a laminated structure using Pt and Co, and Y is added. That is, the coupling magnetic field of the laminated ferripin structure is made higher than when using a single Co—Pt.
The reason why the coupling magnetic field of the laminated ferripin structure is increased by the addition of Y is presumed that, for example, as described above, Y becomes Co-Y and the perpendicular magnetic anisotropy due to Co-Y appears. Can do.

Here, the non-magnetic layer 12b in the magnetization fixed layer 12 is made of Ru, Os, Rh, Ir, Cu, Ag, Au, Re, V, Nb, Ta, Cr, Mo, W, or two or more elements. A laminated film or an alloy can be used.
With such a configuration, the coupling magnetic field of the laminated ferripin structure in the magnetization fixed layer 12 can be increased, and the write error due to the spin torque fluctuation can be reduced without sacrificing the resistance change rate. The stability of the information writing operation can be improved.
Therefore, a highly reliable storage device that operates stably can be realized.

In the storage element 3 of the present embodiment, since the storage layer 14 is a perpendicular magnetization film, the amount of write current required to reverse the direction of the magnetization M14 of the storage layer 14 can be reduced.
By reducing the write current in this way, power consumption when writing to the memory element 3 can be reduced.

Here, in the memory element 3 of the present embodiment as shown in FIG. 4, the base layer 11 to the cap layer 15 are continuously formed in a vacuum apparatus, and then the memory element 3 is processed by etching or the like. It can be manufactured by forming a pattern.
Therefore, there is an advantage that a general semiconductor MOS formation process can be applied when manufacturing a memory device. That is, the storage device of this embodiment can be applied as a general-purpose memory.

In the memory element 3 of the present embodiment, a nonmagnetic element can be added to the memory layer 14.
By adding different elements, effects such as an improvement in heat resistance by preventing diffusion, an increase in magnetoresistance effect, and an increase in withstand voltage due to planarization can be obtained. As the material of the additive element in this case, B, C, N, O, F, Li, Mg, Si, P, Ti, V, Cr, Mn, Ni, Cu, Ge, Nb, Ru, Rh, Pd, Ag, Ta, Ir, Pt, Au, Zr, Hf, W, Mo, Re, Os, or alloys and oxides thereof can be used.

Further, as the memory layer 14, other ferromagnetic layers having different compositions can be directly laminated. Alternatively, a ferromagnetic layer and a soft magnetic layer can be laminated, or a plurality of ferromagnetic layers can be laminated via a soft magnetic layer or a nonmagnetic layer. Even in such a case, the effects of the present technology are exhibited.
In particular, when a configuration in which a plurality of ferromagnetic layers are laminated via a nonmagnetic layer, the strength of interaction between the ferromagnetic layers can be adjusted, so that the magnetization reversal current does not increase. It is possible to obtain an effect that it is possible to suppress it. The material of the nonmagnetic layer in this case is Ru, Os, Re, Ir, Au, Ag, Cu, Al, Bi, Si, B, C, Cr, Ta, Pd, Pt, Zr, Hf, W, Mo. , Nb, V, or alloys thereof.
The film thicknesses of the magnetization fixed layer 12 and the storage layer 14 are preferably 0.5 nm to 30 nm.

It is desirable to reduce the size of the storage element 3 so that the direction of magnetization of the storage layer 14 can be easily reversed with a small current.
For example, the area of the memory element 3 is desirably 0.01 μm ² or less.

The other configuration of the storage element 3 can be the same as the general configuration of the storage element that stores information by spin torque magnetization reversal.
For example, Ag, Cu, Au, Al, Si, Bi, Ta, B, C, O, N, Pd, Pt, Zr, Ta, Hf, Ir, W, Mo, Nb, V, Ru, By adding a nonmagnetic element such as Rh, the magnetic properties can be adjusted, and various physical properties such as other crystal structures, crystallinity, and material stability can be adjusted.
Further, the film configuration (layer structure) of the storage element 3 may be a configuration in which the storage layer 14 is disposed below the magnetization fixed layer 12.

<3. Experimental results>
[Experiment 1]
With respect to the memory element 3 of the present embodiment, in this experiment 1, for the purpose of examining the magnetization reversal characteristics of the magnetization fixed layer 12, the magnetic element is formed using a wafer in which only a sample having a configuration excluding the memory layer 14 from the memory element 3 is formed. The characteristics were investigated.
Specifically, a 300 nm thick thermal oxide film was formed on a 0.725 mm thick silicon substrate, and the memory element 3 having the structure shown in FIG. 5 was formed thereon.

As shown in FIG. 5, the material and film thickness of each layer constituting the magnetization fixed layer 12 were selected as follows.
Magnetization fixed layer 12: Y-added CoPt: 2 nm / Ru: 0.8 nm / CoFeB: 2 nm laminated film.
The perpendicular magnetization film in the magnetization fixed layer 12 is a CoPt film having a thickness of 2 nm to which Y is added at xat%, and “x” is set in the range of 0 to 15 at%.

The material and film thickness of each layer other than the magnetization fixed layer 12 were selected as follows.
-Underlayer 11: Laminated film of 10 nm thick Ta film and 25 nm thick Ru film-Intermediate layer (tunnel insulating layer) 13: 0.9 nm thick magnesium oxide film-Cap layer 15: Ru: 3 nm / Ta : 3 nm laminated film

About this experiment sample, after forming all the above films, heat treatment was performed.
The composition of the CoFeB alloy of the magnetization fixed layer 12 was CoFe80% (Co30% -Fe70%)-B20% (all at%).
The intermediate layer 13 made of a magnesium oxide (MgO) film was formed using an RF magnetron sputtering method, and the other films were formed using a DC magnetron sputtering method.

[Experiment 2]
With respect to the overall configuration of the memory element 3 of the present embodiment, in this experiment 2, for the purpose of examining the resistance change rate, a resistance change rate, an information write error rate [Write Error Rate] using a wafer on which only the memory element 3 is formed. : WER].
Specifically, a 300 nm thick thermal oxide film was formed on a 0.725 mm thick silicon substrate, and the memory element 3 having the structure shown in FIG. 6 was formed thereon.
As shown in FIG. 6, the material and film thickness of each layer constituting the magnetization fixed layer 12 were selected as follows.
Magnetization fixed layer 12: Y-added CoPt: 2 nm / Ru: 0.8 nm / CoFeB: 2 nm laminated film.
The perpendicular magnetization film in the magnetization fixed layer 12 is a CoPt film having a thickness of 2 nm to which Y is added at xat%, and “x” is set in the range of 0 to 15 at%.
The material and film thickness of each layer other than the magnetization fixed layer 12 were selected as follows.
Underlayer 11: Laminated film of 10 nm thick Ta film and 25 nm thick Ru film Intermediate layer (tunnel insulating layer) 13: 0.9 nm thick magnesium oxide film Storage layer 14: CoFeB: 1.5 nm
Cap layer 15: laminated film of Ru: 3 nm / Ta: 3 nm

After all the above films were formed, the sample of this experiment was heat-treated.
In this experiment, the resistance change rate was measured after processing into an element having a diameter of 50 nmΦ. Resistance change rate (%): TMR is based on the resistance difference when the magnetization of the storage layer 14 and the magnetization fixed layer 12 is in the parallel [P] and antiparallel [AP] state.
TMR (%) = (R _AP −R _P ) / R _P × 100
It was calculated by the following formula. ( _RP is the resistance value in the parallel state, _RAP is the resistance value in the antiparallel state)

  FIG. 7A shows the measurement results of the coupling magnetic field and the resistance change rate of the laminated ferripin structure of the magnetization fixed layer obtained from the measurement results of VSM (Vibrating Sample Magnetometer) performed in Experiment 1 and Experiment 2 above. FIG. 7B shows the coupling magnetic field when Y is not added (x = 0).

First, the results of Experiment 1 will be described.
According to FIG. 7, the coupling magnetic field of the laminated ferripin structure is 6.5 kOe when only Co—Pt is used (FIG. 7B). On the other hand, as shown by “●” in FIG. 7A and the left vertical axis, by adding 1 at% of Y to Co—Pt, the coupling magnetic field of the laminated ferripin structure becomes 8.85 kOe, which is increased by about 35%. I was able to confirm. Furthermore, it has been found that a coupling magnetic field of a large laminated ferripin structure is maintained in the range where the Y addition concentration is up to 10 at%.
The reason why the coupling magnetic field of the laminated ferripin structure is increased by the addition of Y can be presumed that, as described above, Y becomes Co-Y, and the perpendicular magnetic anisotropy due to Co-Y is developed.
This experiment demonstrates that adding Y to Co—Pt has the effect of significantly increasing the coupling magnetic field of the laminated ferripin structure.

Further, according to FIG. 7A, it can be confirmed that when the added amount of Y exceeds 10 at%, the coupling magnetic field of the laminated ferripin structure rapidly decreases. The dependency of the coupling magnetic field of the laminated ferripin structure on the Y addition concentration supports the above-described estimation mechanism, and when Y is added excessively, the state of Co in Co—Pt changes. Moreover, it can be estimated that the perpendicular magnetic anisotropy as Co-Pt deteriorates.
From the above experimental results, it was shown that Y addition to Co—Pt is a suitable additive element for increasing the coupling magnetic field of the laminated ferripin structure of the magnetization fixed layer.

Next, the result of Experiment 2 will be described.
As shown by ■ and the right vertical axis in FIG. 7A, the rate of change in resistance (TMR) is constant at about 135% when the Y addition concentration is 10 at% or less, but up to 100% or less when added to 12 at%. It turns out that it has fallen greatly.
Such a decrease in TMR corresponds to a decrease in the coupling magnetic field of the laminated ferripin structure due to excessive addition of Y.

  Therefore, the results of Experiment 1 and Experiment 2 show that Y addition to Co—Pt is a suitable additive element for increasing the coupling magnetic field of the laminated ferripin structure of the magnetization fixed layer, and further, the Y addition concentration is It has been shown that a coupling magnetic field of a large laminated ferripin structure and a high resistance change rate are compatible at 1 to 10 at%.

Further, among the samples prepared in Experiment 2, the information writing error rate was measured for samples with Y addition amount = 0, 1, 5, 10, 12 at%. In the evaluation of the information writing error rate [Write Error Rate: WER], a pulse voltage of 15 ns was applied, and the information writing error generated at that time was measured.
As a result, the magnitude of the coupling magnetic field of this laminated ferripin structure has a great influence on the information write error characteristics in a minute device, and a large amount of coupling magnetic field of the laminated ferripin structure is obtained = 1-10 atm. In the range of%, it has been found that the inversion voltage at which WER is 10 −7 can be kept small.
The WER required during actual memory operation depends on the circuit and the like, but is assumed to be 10 −7 or less. Therefore, the operating characteristics at low WER are extremely important.

The reason why low WER can be realized in a device having a coupling magnetic field of a large laminated ferripin structure can be estimated as follows.
The STT-MRAM uses spin torque when writing information. The effect of this torque is mainly observed in the storage layer 14 but also affects the magnetization fixed layer 12. Here, when the device size is large, the magnetization of the storage layer 14 and the magnetization fixed layer 12 maintains high stability against thermal fluctuation, and therefore the influence of the spin torque applied to the magnetization fixed layer 12 can be ignored.
However, when the device size is, for example, 50 nm or less, the influence of the thermal fluctuation and the influence of the spin torque are superimposed, so that the influence of the spin torque applied to the magnetization fixed layer 12 cannot be ignored.
In particular, in the low WER region, the influence of the spin torque received by the magnetization fixed layer 12 becomes obvious, and unless the coupling magnetic field of the laminated ferripin structure of the magnetization fixed layer 12 is sufficiently increased, the operating voltage increases, that is, the power consumption increases. Therefore, the memory operation is adversely affected.
Therefore, when a device having a magnetization fixed layer using Co—Pt added with 1 to 10 at% of Y and having an increased coupling magnetic field of the laminated ferripin structure is used, the influence of the spin torque applied to the magnetization fixed layer 12 is reduced. Therefore, it can be estimated that the memory operating voltage at a low WER can be kept low.

From the above experimental results, the magnetic material not in contact with the insulating layer in the magnetization fixed layer 12 is made of an alloy or a laminated structure using Pt and Co, Y is added, and Co—Pt alone is used. It was shown that the information writing operation can be stabilized without impairing the resistance change rate in the memory element in which the coupling magnetic field of the laminated ferripin structure is increased as compared with the case of the conventional case.
In particular, it is desirable that the addition amount of the Y element is 12 at% (atomic percentage) or less. This is because, according to the experimental results shown in FIG. 7A, in the laminated ferripin structure, a higher coupling magnetic field can be obtained when Y is added in the range of 12 at% or less than when Y is not added.
Furthermore, it is desirable that the amount of Y element added is 1 at% or more and 10 at% or less. This is because in the laminated ferripin structure, a higher coupling magnetic field can be obtained when the Y addition amount is in the range of 1 to 10 at%, and a desirable resistance change rate can be obtained. Also suitable for WER.

In addition, although the experimental result in the magnetization fixed layer 12 of the structure of Y addition CoPt / Ru / CoFeB was shown so far, the magnetization fixed layer 12 can also take the structure shown in FIG.
FIG. 8A shows the structure of the memory element 3 similar to FIG. 4A. Other structures of the magnetization fixed layer 12 in this case are illustrated in FIGS. 8B to 8E.

FIG. 8B is a configuration example having ferromagnetic layers 12A-1, 12A-2, a nonmagnetic layer 12B, and a ferromagnetic layer 12A-3 in this order as viewed from the intermediate layer 13 side.
The ferromagnetic layer 12A-1 is CoFeB, the ferromagnetic layer 12A-2 is Y-added CoPt, the nonmagnetic layer 12B is Ru, and the ferromagnetic layer 12A-3 is CoPt.
8C is also a configuration example having the ferromagnetic layers 12A-1, 12A-2, the nonmagnetic layer 12B, and the ferromagnetic layer 12A-3 in this order as seen from the intermediate layer 13 side. In this example, both 12A-2 and 12A-3 are Y-added CoPt.

8D shows the ferromagnetic layer 12A-1, the nonmagnetic layer 12B-1, the ferromagnetic layer 12A-2, the nonmagnetic layer 12B-2, and the ferromagnetic layer 12A-3 in this order as viewed from the intermediate layer 13 side. This is a configuration example in which layers and nonmagnetic layers are alternately stacked.
The ferromagnetic layer 12A-1 is CoFeB, the ferromagnetic layer 12A-2 is Y-added CoPt, the nonmagnetic layer 12B is Ru, and the ferromagnetic layer 12A-3 is CoPt.
Similarly to FIG. 8D, FIG. 8E is also referred to as a ferromagnetic layer 12A-1, a nonmagnetic layer 12B-1, a ferromagnetic layer 12A-2, a nonmagnetic layer 12B-2, and a ferromagnetic layer 12A-3 as viewed from the intermediate layer 13 side. In this manner, the ferromagnetic layer and the nonmagnetic layer are alternately laminated. In this case, both ferromagnetic layers 12A-2 and 12A-3 are Y-added CoPt.

In these examples, the nonmagnetic layer 12B-1 can also have a structure of Ta, Nb, Cr, W, Mo, V, Hf, Zr, Ti, or the like.
Further, in place of Ru of the nonmagnetic layers 12B and 12B-2, a single element of Os, Rh, Ir, Cu, Ag, Au, Re, V, Nb, Ta, Cr, Mo, W, or a stack of two or more elements. A film or an alloy can also be used.
In any of the examples in FIG. 8, the magnetization fixed layer 12 has a laminated ferripin structure including at least two ferromagnetic layers and a nonmagnetic layer, and the magnetic layer that does not contact the intermediate layer 13 in the magnetization fixed layer 12. As a material, Y is added to an alloy or a laminated structure using Pt and Co. As a result, the coupling magnetic field of the laminated ferri-pin structure of the magnetization fixed layer 12 is increased, and the write error due to the spin torque fluctuation is reduced without sacrificing the resistance change rate. As a result, the stability of the information writing operation of the memory in the fine device can be improved.
In the above embodiment, an example of a magnetic material containing Y or an alloy or a laminated structure using Pt and Co in the magnetization fixed layer 12 has been described. As a structure corresponding to this, Pt and Co and Y may have a laminated structure. That is, a structure in which the Pt layer, the Y layer, and the Co layer are stacked in the ferromagnetic layer 12c in FIG. 4 and the ferromagnetic layers 12A-2 and 12A-3 in FIGS. 8B to 8E can be considered.
Further, it is also conceivable to use a magnetic material containing Y or an alloy or a laminated structure using Pt and Co as a magnetic material in contact with the intermediate layer 13.

<4. Modification>
The embodiments according to the present technology have been described above, but the present technology should not be limited to the specific examples illustrated above.
For example, the structure of the memory element according to the present technology has a configuration of a magnetoresistive effect element such as a TMR element. The magnetoresistive effect element as the TMR element includes not only the above-described memory device but also a magnetic head and a magnetic head. The present invention can be applied to a hard disk drive equipped with a head, an integrated circuit chip, and various electronic devices such as personal computers, portable terminals, mobile phones, and magnetic sensor devices, and electric devices.

  As an example, FIGS. 9A and 9B show an example in which the magnetoresistive effect element 101 having the structure of the memory element 3 is applied to the composite magnetic head 100. 9A is a perspective view showing the composite magnetic head 100 with a part cut away so that the internal structure of the composite magnetic head 100 can be understood, and FIG. 9B is a cross-sectional view of the composite magnetic head 100.

  The composite magnetic head 100 is a magnetic head used in a hard disk device or the like, and includes a magnetoresistive effect type magnetic head according to the present technology formed on a substrate 122, and an inductive effect on the magnetoresistive effect type magnetic head. A type magnetic head is laminated. Here, the magnetoresistive head is operated as a reproducing head, and the inductive magnetic head is operated as a recording head. That is, the composite magnetic head 100 is configured by combining a reproducing head and a recording head.

The magnetoresistance effect type magnetic head mounted on the composite type magnetic head 100 is a so-called shield type MR head, and includes a first magnetic shield 125 formed on a substrate 122 via an insulating layer 123, and a first magnetic shield 125. The magnetoresistive effect element 101 formed on the magnetic shield 125 via the insulating layer 123 and the second magnetic shield 127 formed on the magnetoresistive effect element 101 via the insulating layer 123 are provided. The insulating layer 123 is made of an insulating material such as Al ₂ O ₃ or SiO ₂ .
The first magnetic shield 125 is for magnetically shielding the lower layer side of the magnetoresistive effect element 101, and is made of a soft magnetic material such as Ni—Fe. A magnetoresistive effect element 101 is formed on the first magnetic shield 125 with an insulating layer 123 interposed therebetween.

In this magnetoresistive effect type magnetic head, the magnetoresistive effect element 101 functions as a magnetosensitive element that detects a magnetic signal from the magnetic recording medium. The magnetoresistive element 101 has a film configuration (layer structure) similar to that of the memory element 3 described above.
The magnetoresistive effect element 101 is formed in a substantially rectangular shape, and one side surface thereof is exposed to the magnetic recording medium facing surface. Bias layers 128 and 129 are disposed at both ends of the magnetoresistive effect element 101. Further, connection terminals 130 and 131 connected to the bias layers 128 and 129 are formed. A sense current is supplied to the magnetoresistive effect element 101 via the connection terminals 130 and 131.
Further, a second magnetic shield layer 127 is provided on the bias layers 128 and 129 via an insulating layer 123.

The inductive magnetic head laminated on the magnetoresistive effect magnetic head as described above has a magnetic core constituted by the second magnetic shield 127 and the upper core 132, and is wound around the magnetic core. And a formed thin film coil 133.
The upper core 132 forms a closed magnetic path together with the second magnetic shield 127 and becomes a magnetic core of the inductive magnetic head, and is made of a soft magnetic material such as Ni—Fe. Here, the front end of the second magnetic shield 127 and the upper core 132 are exposed to the surface facing the magnetic recording medium, and the second magnetic shield 127 and the upper core 132 are in contact with each other at their rear ends. It is formed as follows. Here, the front end portions of the second magnetic shield 127 and the upper core 132 are formed so that the second magnetic shield 127 and the upper core 132 are separated from each other with a predetermined gap g on the surface facing the magnetic recording medium.
That is, in this composite magnetic head 100, the second magnetic shield 127 not only magnetically shields the upper layer side of the magnetoresistive effect element 126 but also serves as the magnetic core of the inductive magnetic head. The magnetic shield 127 and the upper core 132 constitute the magnetic core of the inductive magnetic head. The gap becomes the recording magnetic gap of the inductive magnetic head.

  A thin film coil 133 embedded in the insulating layer 123 is formed on the second magnetic shield 127. Here, the thin film coil 133 is formed so as to wind a magnetic core composed of the second magnetic shield 127 and the upper core 132. Although not shown, both ends of the thin film coil 133 are exposed to the outside, and terminals formed at both ends of the thin film coil 133 are external connection terminals of the inductive magnetic head. That is, when a magnetic signal is recorded on the magnetic recording medium, a recording current is supplied to the thin film coil 133 from these external connection terminals.

As described above, the multilayer structure as a storage element of the present technology can be applied as a reproducing head for a magnetic recording medium, that is, as a magnetosensitive element for detecting a magnetic signal from the magnetic recording medium.
Thus, by applying the laminated structure as a storage element of the present technology to a magnetic head, a highly reliable magnetic head having excellent stability can be realized.

In the description so far, the structure of the storage element 3 including the base layer 11 / the fixed magnetization layer 12 / the intermediate layer 13 / the storage layer 14 / the cap layer 15 has been illustrated, but as the storage element (and magnetic head) in the present technology. As shown in FIG. 10, a fixed magnetization layer such as an underlayer 11 / lower magnetization fixed layer 12L / lower intermediate layer 13L / storage layer 14 / upper intermediate layer 13U / upper magnetization fixed layer 12U / cap layer 15 It is also possible to adopt a structure as a memory element 3 ′ in which 12 is divided and arranged at the lower part and upper part of the memory layer 14.
FIG. 10 also shows the direction of the magnetization M12L of the lower magnetization fixed layer 12L and the direction of the magnetization M12U of the upper magnetization fixed layer 12U. In this case, the directions of the magnetization M12L and the magnetization M12U are reversed. It will be.
In this case, the lower intermediate layer 13L and the upper intermediate layer 13U are formed of an oxide film such as MgO in the same manner as the intermediate layer 13.

  Even when the magnetization fixed layer 12 is divided and arranged in the lower / upper portion as described above, the lower / upper magnetization fixed layers 12 have the same structure as the magnetization fixed layer 12 described so far, that is, the magnetization fixed. Of the magnetic materials in the layer 12, the magnetic material not in contact with the intermediate layer (13U, 13L) is an alloy or a laminated structure using Pt and Co, and Y is added. By adopting a structure as a memory element in which the coupling strength of the laminated ferripin structure is increased as compared with the case of using, the effect of improving the memory operation stability can be obtained similarly.

  In the description so far, the case where the composition of the CoFeB of the storage layer 14 and the magnetization fixed layer 12 is the same has been exemplified. However, the composition has various other configurations without departing from the gist of the present technology. To get.

Further, in the description so far, the ferromagnetic layers 12a and 12A-1 in contact with the intermediate layer 13 in the magnetization fixed layer 12 are single layers of CoFeB. However, elements and oxides may be used as long as the coupling magnetic field is not significantly reduced. It is also possible to add.
Examples of elements to be added include Ta, Hf, Nb, Zr, Cr, Ti, V, W, and examples of oxides include MgO, AlO, and SiO ₂ .
Further, the magnetization fixed layer 12 is not limited to the laminated ferrimagnetic structure.

The underlayer 11 and the cap layer 15 may be a single material or a laminated structure of a plurality of materials.
The present technology can also be applied to a so-called top laminated ferri-type STT-MRAM. In this case as well, the effect of improving the memory operation stability can be obtained by using Y-added Co-Pt.

  Note that the effects described in the present specification are merely examples and are not limited, and other effects may be obtained.

The present technology can also employ the following configurations.
(1) a storage layer having magnetization perpendicular to the film surface and having the magnetization direction changed corresponding to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer is changed, and information is stored in the storage layer.
The magnetization fixed layer has a laminated ferrimagnetic structure including at least two ferromagnetic layers and a nonmagnetic layer;
As the magnetic material in the magnetization fixed layer, an alloy using Pt and Co or a laminated structure, and a magnetic material containing Y is used.
(2) The magnetic material that is not in contact with the intermediate layer in the magnetization fixed layer is an alloy or a laminated structure using Pt and Co, and includes Y but contains a magnetic material. The memory element described.
(3) The memory element according to (2), wherein the addition amount of the Y element is 12 at% or less.
(4) The memory element according to (2) or (3), wherein an addition amount of the Y element is 1 at% or more and 10 at% or less.
(5) The memory element according to any one of (2) to (4), wherein a magnetic material in contact with the intermediate layer in the magnetization fixed layer is formed of a CoFeB magnetic layer.
(6) a storage layer having magnetization perpendicular to the film surface and having the magnetization direction changed corresponding to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer is changed, and information is stored in the storage layer.
As the magnetic material in the magnetization fixed layer, an alloy using Pt and Co or a laminated structure, and a magnetic material containing Y is used.
(7) The memory element according to (6), wherein an addition amount of the Y element is 12 at% or less.
(8) The memory element according to (6) or (7), wherein an addition amount of the Y element is 1 at% or more and 10 at% or less.
(9) 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 having magnetization perpendicular to the film surface and having the magnetization direction changed in response to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer is changed, and information is stored in the storage layer.
The magnetization fixed layer has a laminated ferrimagnetic structure including at least two ferromagnetic layers and a nonmagnetic layer;
As the magnetic material in the magnetization fixed layer, an alloy or a laminated structure using Pt and Co and a magnetic material containing Y is used.
The storage element is disposed between the two types of wirings,
A storage device in which a current in the stacking direction flows through the storage element through the two types of wirings and spin-polarized electrons are injected.
(10) a storage layer having magnetization perpendicular to the film surface and having the magnetization direction changed according to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer changes,
The magnetization fixed layer has a laminated ferrimagnetic structure including at least two ferromagnetic layers and a nonmagnetic layer;
A magnetic head using a magnetic material containing Y or an alloy or a laminated structure using Pt and Co as the magnetic material in the magnetization fixed layer.

  DESCRIPTION OF SYMBOLS 1 ... Gate electrode, 2 ... Element isolation layer, 3 and 3 '... Memory element, 4 ... Contact layer, 6 ... Bit line, 7 ... Source region, 8 ... Drain region, 9 ... Wiring, 10 ... Semiconductor substrate, 11 ... Underlayer, 12 ... magnetization fixed layer, 12L ... lower magnetization fixed layer, 12U ... upper magnetization fixed layer, 13 ... intermediate layer, 13L ... lower intermediate layer, 13U ... upper intermediate layer, 14 ... storage layer, 15 ... cap layer

First, the storage element according to the present technology has a magnetization perpendicular to the film surface, the magnetization direction of which changes according to information, and a reference for information stored in the storage layer A layer structure having a magnetization fixed layer having magnetization perpendicular to the film surface, and an intermediate layer made of a nonmagnetic material provided between the storage layer and the magnetization fixed layer, and spin-polarized in the stacking direction of the layer structure. By injecting polarized electrons, the magnetization direction of the storage layer changes, and information is stored in the storage layer. The magnetization fixed layer has a laminated ferrimagnetic structure including three ferromagnetic layers and a nonmagnetic layer, and one ferromagnetic layer in contact with the intermediate layer in the magnetization fixed layer has CoFeB. Each of the other ferromagnetic layers not in contact with the intermediate layer in the magnetization fixed layer has an alloy or a laminated structure using Pt and Co, and the intermediate layer in the magnetization fixed layer. At least one of the other ferromagnetic layers not in contact with the layer is made of an alloy containing Y or a laminated structure, and the nonmagnetic layer is a ferromagnetic layer of any two of the three ferromagnetic layers. Is located between the layers .
That is, by using a magnetization fixed layer having a laminated ferrimagnetic structure having a large coupling magnetic field in the STT-MRAM memory element, a write error due to spin torque fluctuation is reduced. The reason why the coupling magnetic field of the laminated ferrimagnetic structure can be increased by adding Y as compared with the case of using only Co—Pt is, for example, that Y becomes Co—Y and the perpendicular magnetic anisotropy due to Co—Y appears. It is possible that
Secondly, in the memory element according to the present technology described above , among the other ferromagnetic layers not in contact with the intermediate layer in the magnetization fixed layer, the intermediate layer-side ferromagnetic layer includes an alloy or a laminate containing Y. It is structured .
Third, in the memory element according to the above-described present technology, it is preferable that the amount of addition of the Y element is 12 at% (atomic percentage) or less.
In the above-described laminated ferripin structure, a higher coupling magnetic field can be obtained when Y is added in the range of 12 at% or less than when Y is not added.
Fourth, in the memory element according to the present technology described above, it is desirable that the amount of addition of the Y element is 1 at% or more and 10 at% or less.
In the above laminated ferripin structure, a higher coupling magnetic field and a preferable resistance change rate can be obtained when the Y addition amount is in the range of 1 to 10 at% .

Claims (10)

A storage layer having magnetization perpendicular to the film surface and having the magnetization direction changed in response to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer is changed, and information is stored in the storage layer.
The magnetization fixed layer has a laminated ferrimagnetic structure including at least two ferromagnetic layers and a nonmagnetic layer;
As the magnetic material in the magnetization fixed layer, an alloy using Pt and Co or a laminated structure, and a magnetic material containing Y is used. The memory element according to claim 1, wherein the magnetic material not in contact with the intermediate layer in the magnetization fixed layer is an alloy or a laminated structure using Pt and Co and includes Y but includes a magnetic material. . The memory element according to claim 2, wherein an addition amount of the Y element is 12 at% or less. The memory element according to claim 2, wherein an addition amount of the Y element is 1 at% or more and 10 at% or less. The storage element according to claim 2, wherein the magnetic material in contact with the intermediate layer in the magnetization fixed layer is formed of a CoFeB magnetic layer. A storage layer having magnetization perpendicular to the film surface and having the magnetization direction changed in response to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer is changed, and information is stored in the storage layer.
As the magnetic material in the magnetization fixed layer, an alloy using Pt and Co or a laminated structure, and a magnetic material containing Y is used. The memory element according to claim 6, wherein an addition amount of the Y element is 12 at% or less. The memory element according to claim 6, wherein an addition amount of the Y element is 1 at% or more and 10 at% or less. 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 having magnetization perpendicular to the film surface and having the magnetization direction changed in response to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer is changed, and information is stored in the storage layer.
The magnetization fixed layer has a laminated ferrimagnetic structure including at least two ferromagnetic layers and a nonmagnetic layer;
As the magnetic material in the magnetization fixed layer, an alloy or a laminated structure using Pt and Co and a magnetic material containing Y is used.
The storage element is disposed between the two types of wirings,
A storage device in which a current in the stacking direction flows through the storage element through the two types of wirings and spin-polarized electrons are injected. A storage layer having magnetization perpendicular to the film surface and having the magnetization direction changed in response to information;
A magnetization fixed layer having magnetization perpendicular to a film surface serving as a reference of information stored in the storage layer;
A nonmagnetic intermediate layer provided between the storage layer and the magnetization fixed layer;
A layer structure having
By injecting spin-polarized electrons in the stacking direction of the layer structure, the magnetization direction of the storage layer changes,
The magnetization fixed layer has a laminated ferrimagnetic structure including at least two ferromagnetic layers and a nonmagnetic layer;
A magnetic head using a magnetic material containing Y or an alloy or a laminated structure using Pt and Co as the magnetic material in the magnetization fixed layer.

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