JP4371781B2 - Magnetic cell and magnetic memory - Google Patents

Magnetic cell and magnetic memory Download PDF

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JP4371781B2
JP4371781B2 JP2003396201A JP2003396201A JP4371781B2 JP 4371781 B2 JP4371781 B2 JP 4371781B2 JP 2003396201 A JP2003396201 A JP 2003396201A JP 2003396201 A JP2003396201 A JP 2003396201A JP 4371781 B2 JP4371781 B2 JP 4371781B2
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JP2004193595A (en
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志保 中村
裕一 大沢
茂 羽根田
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株式会社東芝
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  The present invention relates to a magnetic cell and a magnetic memory, and more particularly to a magnetic cell and a magnetic memory capable of writing by passing spin-polarized electrons.

  In order to control the magnetization direction of the magnetic material, a method of applying a magnetic field has been conventionally employed. For example, in a hard disk drive, writing is performed by reversing the magnetization direction of a medium by a magnetic field generated from a recording head. Further, in the solid-state magnetic memory, the magnetization direction of the cell is controlled by applying a current magnetic field generated by passing a current through a wiring provided in the vicinity of the magnetoresistive element to the cell. The magnetization direction control by these external magnetic fields has an old history and can be said to be an established technology.

  On the other hand, due to recent advances in nanotechnology, it has become necessary to rapidly reduce the size of magnetic materials and control magnetization locally at the nanoscale. However, it is difficult to localize the magnetic field because it has the property of fundamentally spreading into space. As the size of a bit or cell becomes smaller, the problem of “crosstalk” in which a magnetic field extends to the adjacent bit or cell when a specific bit or cell is selected and its magnetization direction is controlled becomes significant. Become. Further, if the magnetic field generation source is made small in order to localize the magnetic field, there arises a problem that a sufficient generated magnetic field cannot be obtained.

Recently, a “current direct drive type magnetization reversal” has been found that causes a magnetization reversal by passing a current through a magnetic material (for example, see Non-Patent Document 1).
The reversal of magnetization due to electric current is caused by the fact that the spin-polarized electron's angular momentum generated when the spin-polarized current passes through the magnetic layer is transmitted to and acts on the angular momentum of the magnetic material whose magnetization is to be reversed. It is a phenomenon that causes If this phenomenon is used, it is possible to act on a nanoscale magnetic material more directly, and recording on a finer magnetic material becomes possible.
FJ Albert, et al., Appl. Phy. Lett. 77, 3809 (2000)

  However, at present, there is a problem that the reversal current for reversing the magnetization is as extremely large as 10 mA to several mA even when the cell size is about 100 nanometers to several tens of nanometers. That is, in order to prevent element destruction due to current, to prevent heat generation, and to further reduce power consumption, a magnetic cell structure that can reverse magnetization with as little current as possible is desired.

  The present invention has been made based on recognition of such a problem, and an object thereof is to provide a magnetic cell capable of reducing a reversal current at the time of magnetization reversal by direct current driving and a magnetic memory using the same. There is.

In order to achieve the above object, a first magnetic cell of the present invention includes a first ferromagnetic layer in which magnetization is fixed in a first direction perpendicular to the film surface, and magnetization in the first direction. Is provided between the second ferromagnetic layer fixed in the opposite second direction, the first ferromagnetic layer, and the second ferromagnetic layer, and has a variable magnetization direction. A ferromagnetic layer, a first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, the second ferromagnetic layer, and the third ferromagnetic layer; A second intermediate layer provided between,
The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each of which the second intermediate layer is provided constitutes a magnetoresistive effect element, and spin-polarized electrons are caused to flow by passing a current between the first and second ferromagnetic layers. It is possible to determine the direction of magnetization of the third ferromagnetic layer by acting on the magnetic layer in a direction corresponding to the direction of the current.

  By making the magnetizations of the first and second ferromagnetic layers, i.e., two magnetic pinned layers antiparallel, the spin directions acting on the third ferromagnetic layer, i.e., the magnetic recording layer, finally become the same direction and are doubled. The action works. As a result, the current for reversing the magnetization of the magnetic recording layer can be reduced.

Here, if the easy axis of magnetization of the third ferromagnetic layer is parallel to the first direction, writing by a spin-polarized current is more reliably performed, and at the time of reading Can utilize a large magnetoresistance effect.

The electrical resistance between the first ferromagnetic layer and the third ferromagnetic layer is first when the magnetization direction of the third ferromagnetic layer is the same as the first direction. And the second ferromagnetic layer has a second value greater than the first value when the magnetization direction of the third ferromagnetic layer is the same as the second direction. The electrical resistance between the third ferromagnetic layer has a third value when the magnetization direction of the third ferromagnetic layer is the same as the second direction, and the third ferromagnetic layer has a third value. If the magnetization direction of the layer becomes the fourth value larger than the third value in the same state as the first direction, the combination of the so-called normal type magnetoresistance effect is ensured. Can write.

  In addition, when an electron current flows from the first ferromagnetic layer to the second ferromagnetic layer via the third ferromagnetic layer, the magnetization direction of the third ferromagnetic layer Is the first direction, and when an electron current flows from the second ferromagnetic layer to the first ferromagnetic layer via the third ferromagnetic layer, the third direction The direction of magnetization of the ferromagnetic layer can be the second direction.

A first ferromagnetic layer whose magnetization is fixed in a first direction; a second ferromagnetic layer whose magnetization is fixed in a second direction opposite to the first direction; A third ferromagnetic layer having a variable magnetization direction, the first ferromagnetic layer, and the third ferromagnetic layer being provided between the first ferromagnetic layer and the second ferromagnetic layer. comprising a first intermediate layer provided between, and a second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer, the first ferromagnetic The first intermediate layer provided between the layer and the third ferromagnetic layer, and the second intermediate layer between the second ferromagnetic layer and the third ferromagnetic layer. Each of which constitutes a magnetoresistive effect element and causes spin-polarized electrons to act on the third ferromagnetic layer by passing a current between the first and second ferromagnetic layers. Said The direction of magnetization of the ferromagnetic layer and can be determined in the direction corresponding to the direction of the current,
The electrical resistance between the first ferromagnetic layer and the third ferromagnetic layer is a first value when the direction of the magnetization of the third ferromagnetic layer is the same as the first direction. And the magnetization direction of the third ferromagnetic layer becomes a second value smaller than the first value in the same state as the second direction,
The electrical resistance between the second ferromagnetic layer and the third ferromagnetic layer is a third value when the magnetization direction of the third ferromagnetic layer is the same as the second direction. If the magnetization direction of the third ferromagnetic layer becomes the fourth value smaller than the third value in the same state as the first direction, the so-called reverse type magnetic Reliable writing can be performed by the combination showing the resistance effect.

  If the film thickness of the first intermediate layer and the film thickness of the second intermediate layer are different from each other, it is possible to easily read the magnetization of the third ferromagnetic layer using the magnetoresistive effect. .

  Further, even if the electric resistance of the first intermediate layer and the electric resistance of the second intermediate layer are different from each other, it is possible to easily read the magnetization of the third ferromagnetic layer using the magnetoresistance effect.

  In addition, even if one of the first and second intermediate layers includes an intermediate material layer, the magnetization of the third ferromagnetic layer can be easily read using the magnetoresistive effect.

A first ferromagnetic layer whose magnetization is fixed in a first direction; a second ferromagnetic layer whose magnetization is fixed in a second direction opposite to the first direction; A third ferromagnetic layer having a variable magnetization direction, the first ferromagnetic layer, and the third ferromagnetic layer being provided between the first ferromagnetic layer and the second ferromagnetic layer. comprising a first intermediate layer provided between, and a second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer, the first ferromagnetic The first intermediate layer provided between the layer and the third ferromagnetic layer, and the second intermediate layer between the second ferromagnetic layer and the third ferromagnetic layer. Each of which constitutes a magnetoresistive effect element and causes spin-polarized electrons to act on the third ferromagnetic layer by passing a current between the first and second ferromagnetic layers. Said The direction of magnetization of the ferromagnetic layer can be determined according to the direction of the current, and one of the first and second intermediate layers is made of an insulator having a pinhole, and the pinhole is Even if it is filled with the material of the ferromagnetic layer adjacent to both sides of the insulator, it is possible to easily read the magnetization of the third ferromagnetic layer using the magnetoresistance effect.

  Further, even when the first and second ferromagnetic layers are different in at least one of film thickness and material, it is possible to easily read the magnetization of the third ferromagnetic layer using the magnetoresistive effect.

  Further, if the first and second ferromagnetic layers are formed by magnetostatic coupling, these antiparallel magnetizations can be easily realized.

  Further, at least one of the first and second ferromagnetic layers may have a magnetization direction fixed by an adjacent antiferromagnetic layer.

A first ferromagnetic layer whose magnetization is fixed in a first direction; a second ferromagnetic layer whose magnetization is fixed in a second direction opposite to the first direction; A third ferromagnetic layer having a variable magnetization direction, the first ferromagnetic layer, and the third ferromagnetic layer being provided between the first ferromagnetic layer and the second ferromagnetic layer. A first intermediate layer provided therebetween, and a second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer,
The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons act on the third ferromagnetic layer, so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. It is possible to determine the direction according to the direction,
A nonmagnetic layer, a fourth ferromagnetic layer, and an antiferromagnetic layer are stacked in this order adjacent to at least one of the first and second ferromagnetic layers, and adjacent to both sides of the nonmagnetic layer. The magnetization direction of the ferromagnetic layer may be fixed in the same direction.

  Alternatively, a nonmagnetic layer, a fourth ferromagnetic layer, and an antiferromagnetic layer are stacked in this order adjacent to at least one of the first and second ferromagnetic layers, and adjacent to both sides of the nonmagnetic layer. The magnetization direction of the ferromagnetic layer may be fixed in the opposite direction.

On the other hand, the second magnetic cell of the present invention includes a first magnetization pinned portion including a first ferromagnetic layer whose magnetization is fixed in a first direction perpendicular to the film surface, and the magnetization is the first A second magnetization pinned portion including a second ferromagnetic layer fixed in a second direction opposite to the first direction, and provided between the first magnetization pinned portion and the second magnetization pinned portion. A third ferromagnetic layer having a variable magnetization direction, a first intermediate layer provided between the first magnetization pinned portion and the third ferromagnetic layer, and the second magnetization. A second intermediate layer provided between the fixed portion and the third ferromagnetic layer,
The easy axis of magnetization of the third ferromagnetic layer is parallel to the first direction, and at least one of the first and second magnetization pinned portions includes a ferromagnetic layer and a nonmagnetic layer. The stacked layers are alternately stacked and the ferromagnetic layers are antiferromagnetically coupled through the nonmagnetic layer, and the first ferromagnetic layer is adjacent to the first intermediate layer, and A second ferromagnetic layer adjacent to the second intermediate layer , wherein the first intermediate layer is provided between the first ferromagnetic layer and the third ferromagnetic layer; and The second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer constitutes a magnetoresistive effect element, and the first magnetization pinned portion and the second magnetic layer By causing a current to flow between the magnetization pinned portions, spin-polarized electrons act on the third ferromagnetic layer to change the magnetization direction of the third ferromagnetic layer. And characterized in that a determinable in the direction corresponding to the direction of current.

  Here, one of the first and second magnetization fixed portions has an even number of the ferromagnetic layers, and the other one of the first and second magnetization fixed portions has the ferromagnetic layer. Is an odd number, the magnetization directions of the two outermost magnetic layers are parallel to each other. When the two outer magnetic layers FM are pinned by an antiferromagnetic layer (not shown), since the directions to be fixed are the same, there is an advantage that the formation process is easy.

The first and second magnetization pinned portions, the third ferromagnetic layer, and the first and second intermediate layers may further include a substrate stacked thereon, The number of the ferromagnetic layers included in the second magnetization pinned portion provided on the side far from the substrate may be an even number. The magnetic pinned layer far from the substrate is likely to have a leakage magnetic field from the magnetic pole because the lateral dimension is reduced by microfabrication. This magnetic bias due to the leakage magnetic field shifts the reversal current, and the reversal current becomes larger than when there is no magnetic field bias in either direction. On the other hand, if a magnetic pinned structure using a laminated film in which an even number of ferromagnetic layers are antiferromagnetically coupled is employed, the shift of the reversal current can be prevented and the reversal current can be kept low in any direction.
A first ferromagnetic layer whose magnetization is fixed in a first direction; a second ferromagnetic layer whose magnetization is fixed in a second direction opposite to the first direction; A third ferromagnetic layer having a variable magnetization direction, the first ferromagnetic layer, and the third ferromagnetic layer being provided between the first ferromagnetic layer and the second ferromagnetic layer. comprising a first intermediate layer provided between, and a second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer, the first ferromagnetic The first intermediate layer provided between the layer and the third ferromagnetic layer, and the second intermediate layer between the second ferromagnetic layer and the third ferromagnetic layer. Each of which constitutes a magnetoresistive effect element and causes spin-polarized electrons to act on the third ferromagnetic layer by passing a current between the first and second ferromagnetic layers. Said The direction of magnetization of the ferromagnetic layer can be determined according to the direction of the current, and the third ferromagnetic layer is a laminate in which a plurality of layers made of ferromagnetic materials are laminated. Thus, stable writing can be performed reliably and easily.

  If one of the first and second intermediate layers is made of a conductor and the other is made of an insulator, the magnetization of the third ferromagnetic layer using the magnetoresistance effect can be read out. Can be easily done.

  A third intermediate layer provided adjacent to the second ferromagnetic layer; a fourth ferromagnetic layer provided adjacent to the third intermediate layer and having a variable magnetization direction; A fourth intermediate layer provided adjacent to the fourth ferromagnetic layer; and a fourth intermediate layer provided adjacent to the fourth intermediate layer, wherein a magnetization direction is substantially fixed in the first direction. A fifth ferromagnetic layer may be further provided.

  On the other hand, a magnetic memory according to the present invention is characterized by comprising a memory cell in which any one of the plurality of magnetic cells is provided in a matrix with an insulator interposed therebetween.

The memory cell includes a plurality of magnetic cells arranged in a matrix with an insulator interposed therebetween, and each of the plurality of magnetic cells has a magnetization fixed in a first direction perpendicular to the film surface. A first ferromagnetic layer; a second ferromagnetic layer whose magnetization is fixed in a second direction opposite to the first direction; the first ferromagnetic layer and the second ferromagnetic layer; A third ferromagnetic layer having a variable magnetization direction, and a first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer, wherein the first ferromagnetic layer and the third ferromagnetic layer Those having the first intermediate layer provided therebetween and those having the second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer have a magnetoresistive effect, respectively. Constitutes an element, the spin-polarized electrons by passing a current between the first and second ferromagnetic layers is allowed to act on the third ferromagnetic layer of the magnetization of the third ferromagnetic layer The magnetic memory can be characterized in that the direction can be determined according to the direction of the current, and each of the magnetic cells on the memory cell can be accessed by a probe.

  In addition, a word line and a bit line are connected to each of the magnetic cells on the memory cell, and information can be recorded or read from a specific magnetic cell by selecting the word line and the bit line. It can also be.

  According to the present invention, it is possible to provide a magnetic cell capable of locally writing magnetization in a small-sized magnetic body with low power consumption, and furthermore, a magnetic cell capable of reading the written magnetization using the magnetoresistive effect. Can provide a cell. Since these magnetic cells are extremely small, they have a great effect on increasing the density and functionality of the magnetic element and reducing the overall size of the device including the magnetic element, and have great industrial advantages.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view illustrating the basic cross-sectional structure of the magnetic cell according to the first embodiment of the invention. This magnetic cell has two magnetic pinned layers (magnetic pinned layers) C1 and C2 whose magnetizations M1 and M2 are antiparallel to each other, one magnetic recording layer (magnetic recording layer) A whose magnetization direction is variable, and magnetic Intermediate layers B1 and B2 are provided between the recording layer A and the magnetic pinned layer.

  By flowing the current I between the upper and lower fixed layers C1 and C2, the direction of the magnetization M of the magnetic recording layer A can be controlled. Specifically, the direction of the magnetization M of the magnetic recording layer A can be reversed by changing the direction (polarity) in which the current I flows. When information is recorded, “0” and “1” may be assigned in accordance with the direction of the magnetization M.

  In the magnetic cell of the present invention, the magnetization direction of each layer is not limited to the in-plane direction, and may be a direction substantially perpendicular to the film surface.

  FIG. 2 is a schematic diagram showing a cross-sectional structure of a magnetic cell whose magnetization is controlled in a direction perpendicular to the film surface. In the case of this magnetic cell, the magnetizations M, M1, and M2 are controlled in a direction substantially perpendicular to the film surface. Even in this case, the direction of the magnetization M of the magnetic recording layer A can be controlled by flowing the current I between the upper and lower fixed layers C1 and C2.

  Next, the “write” mechanism in the magnetic cell of the present invention will be described.

  FIG. 3 is a schematic cross-sectional view for explaining the mechanism of “writing” in the magnetic cell shown in FIG. A mechanism in which the two magnetic pinned layers C1 and C2 are provided and the current I is caused to flow across the interface between them to perform writing on the magnetic recording layer A will be described as follows. First, the case where both the magnetoresistive effect via the intermediate layer B1 and the magnetoresistive effect via the intermediate layer B2 are normal types will be described. Here, the “normal type” magnetoresistance effect refers to a case where the electrical resistance is higher when the magnetizations of the magnetic layers on both sides of the intermediate layer are antiparallel than when they are parallel. That is, in the case of the normal type, the electric resistance between the magnetic pinned layer C1 and the magnetic recording layer A via the intermediate layer B1 is greater than when the magnetic pinned layer C1 and the magnetic recording layer A are parallel to each other than when they are antiparallel. Lower. Further, the electric resistance between the magnetic pinned layer C2 and the magnetic recording layer A via the intermediate layer B2 is also lower when the magnetization of the magnetic pinned layer C2 and the magnetic recording layer A are parallel than when antiparallel.

  First, in FIG. 3A, electrons that have passed through the first magnetic pinned layer C1 having the magnetization M1 have a spin in the direction of the magnetization M1, and when this flows to the magnetic recording layer A, The angular momentum is transmitted to the magnetic recording layer A and acts on the magnetization M. On the other hand, the magnetization M2 of the second magnetic pinned layer C2 is opposite to the magnetization M1. For this reason, at the interface where the flow of electrons enters the second magnetic pinned layer C2, electrons having a spin in the same direction as the magnetization M1 (rightward in the figure) are reflected. The reverse spins of the reflected electrons still act on the magnetic recording layer A. That is, since spin electrons in the same direction as the magnetization of the first magnetic pinned layer act twice on the magnetic recording layer A, a substantially double writing effect can be obtained. As a result, writing to the magnetic recording layer A can be performed with a smaller current than in the past.

  FIG. 3B shows a case where the current I is inverted. In this case, the electrons constituting the current I first have a spin in this direction (leftward in the figure) due to the action of the magnetization M2 of the second magnetic pinned layer C2. The spin electrons act on the magnetization M in the magnetic recording layer A. Further, the spin electrons are reflected at the interface with the first magnetic pinned layer C1 having the magnetization M1 opposite to the spin electrons, accumulated in the intermediate layer B2, and once again act on the magnetization M of the magnetic recording layer A.

  The case where the magnetoresistive effect between the magnetic fixing C1 and C2 and the magnetic recording A via the intermediate layers B1 and B2 is “normal type” has been described above.

Next, the case where these are “reverse types” will be described.
FIG. 4 is a schematic cross-sectional view for explaining the mechanism of “writing” when the magnetic cell exhibits a reverse type magnetoresistance effect.

  That is, in the case of the reverse type, the electrical resistance between the magnetic pinned layer C1 and the magnetic recording layer A via the intermediate layer B1 is antiparallel when the magnetizations of the magnetic pinned layer C1 and the magnetic recording layer A are parallel. Higher than. Further, the electric resistance between the magnetic pinned layer C2 and the magnetic recording layer A via the intermediate layer B2 is also higher when the magnetizations of the magnetic pinned layer C2 and the magnetic recording layer A are parallel than when they are antiparallel.

  When the magnetoresistance effect via the intermediate layers B1 and B2 is a reverse type, the spin electrons acting on the magnetic recording layer A from the magnetic pinned layer C1 are as shown in FIG. ) In the opposite direction. Also, the spin electrons acting on the magnetic recording layer A from the magnetic pinned layer C2 are in the opposite direction to those in FIG. As a result, the direction of the magnetization M of the magnetic recording layer A is antiparallel to the magnetization M1 of the magnetic pinned layer C1, as shown in FIG. 4A, and is the same direction as the magnetization M2 of the magnetic pinned layer C2.

  On the other hand, when an electron current is passed from the magnetic pinned layer C2 toward the magnetic pinned layer C1, as shown in FIG. 4B, the direction of the magnetization M of the magnetic recording layer A is the magnetization of the magnetic pinned layer C1. The direction is the same as M1.

  As described above, when the magnetoresistive effect via the intermediate layers B1 and B2 is the normal type or the reverse type, the magnetization of the magnetic recording layer A depends on the electron flow direction. The direction of M is determined.

  However, when either one of the magnetoresistive effects via the intermediate layers B1 and B2 is a normal type and the other is a reverse type, the spin polarization degree of electrons flowing into the magnetic recording layer A becomes small. This is disadvantageous for writing. For example, the magnetoresistive effect between the magnetic pinned layer C1 and the magnetic recording layer A via the intermediate layer B1 is a normal type, while between the magnetic pinned layer C2 and the magnetic free layer A via the intermediate layer B2. When the magnetoresistive effect is a reverse type, the spin direction of electrons acting on the magnetic recording layer A is reversed at the interface between the intermediate layers B1 and B2, and therefore the effect of the present invention is hardly obtained.

  As described above, according to the present embodiment, the magnetizations M1 and M2 of the two magnetic pinned layers are made antiparallel, so that the spin direction acting on the magnetic recording layer A is finally the same direction and is doubled. The action works. As a result, the current for reversing the magnetization of the magnetic recording layer A can be reduced.

  The “write” mechanism described above is the same in the magnetic cell in which the magnetization is controlled in the direction perpendicular to the film surface as shown in FIG.

  FIG. 5 is a schematic cross-sectional view for explaining the mechanism of “writing” in the magnetic cell shown in FIG. In this figure, the same elements as those described above with reference to FIGS. 1 to 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 5, even when the magnetization directions are perpendicular, the spin directions acting on the magnetic recording layer A are finally the same by making the magnetizations M1 and M2 of the two magnetic pinned layers antiparallel. The direction is doubled. As a result, the current for reversing the magnetization of the magnetic recording layer A can be reduced.

  Next, a method of “reading” in the magnetic cell of this embodiment will be described. In the magnetic cell of the present embodiment, the direction of the magnetization M of the magnetic recording layer A can be detected by utilizing the “magnetoresistance effect” in which the electric resistance changes depending on the relative direction of the magnetization of each layer.

  FIG. 6 is a conceptual diagram for explaining the magnetic cell reading method of the present embodiment. That is, when the magnetoresistance effect is used, the magnetoresistance may be measured by passing a sense current I between one of the magnetic pinned layers C1 and C2 and the magnetic recording layer. In FIG. 6, the case where the magnetic resistance is measured between the first magnetic pinned layer C1 and the magnetic recording layer A is illustrated, but on the contrary, the second magnetic pinned layer C2 and the magnetic recording layer A are shown. The magnetoresistance may be measured between

  FIG. 7 is a conceptual diagram for explaining the change in magnetoresistance due to the relative orientation of magnetization. That is, FIG. 5A shows the case where the magnetization M1 of the magnetic pinned layer C1 and the magnetization M of the magnetic recording layer A are in the same direction. In this case, the magnetoresistance detected by passing the sense current I through these becomes a relatively small value in the normal type magnetoresistance effect, and becomes a relatively large value in the reverse type magnetoresistance effect.

On the other hand, FIG. 7B shows a case where the magnetization M1 of the magnetic pinned layer C1 and the magnetization M of the magnetic recording layer A are antiparallel. In this case, the magnetoresistance detected by passing the sense current I through these becomes a relatively large value in the normal type magnetoresistance effect, and becomes a relatively small value in the reverse type magnetoresistance effect.
By associating “0” and “1” with these different resistances, binary data can be recorded and read.

  On the other hand, there is also a method of detecting the magnetoresistance by flowing a sense current through both ends of the magnetic cell. That is, the magnetoresistance is detected by passing a sense current between the first magnetic pinned layer C1 and the second magnetic pinned layer C2. However, in the present invention, the magnetizations M1 and M2 of the pair of magnetic pinned layers C1 and C2 are antiparallel. For this reason, when the “symmetric structure”, that is, the magnitude of the spin-dependent scattering of the magnetic pinned layers C1 and C2 is the same, or the spin polarization degree of electrons acting on the magnetic recording layer from the magnetic pinned layers C1 and C2 is the same. If so, the detected magnetic resistance becomes the same regardless of the direction of the magnetization M of the magnetic recording layer A. Therefore, it is necessary to adopt an “asymmetric structure”.

  FIG. 8 is a schematic cross-sectional view illustrating a first specific example of an asymmetric structure.

  As an example of the asymmetric structure, the magnitudes of the magnetizations M1 and M2 can be changed by making the magnetic pinned layers C1 and C2 have different thicknesses and materials. In the case of the specific example shown in FIG. 8, the second magnetic pinned layer C2 is formed thicker than the first magnetic pinned layer C1, so that the contribution of spin-dependent bulk scattering by the magnetic pinned layer C2 is greater than that of C1. Enlarge. In this way, when “reading” is performed by flowing a sense current through the magnetic pinned layers C1 and C2, the detected magnetic resistance differs depending on the direction of the magnetization M of the magnetic recording layer A.

  However, as shown in FIG. 8, instead of changing the thicknesses of the first and second magnetic pinned layers C1 and C2, the magnitude of the spin-dependent scattering by the magnetic pinned layers C1 and C2 is changed by changing their materials. You may change it.

  FIG. 9A is a schematic cross-sectional view illustrating a second specific example of an asymmetric structure.

  That is, in the case of this specific example, the thicknesses of the intermediate layers B1 and B2 are different. That is, the intermediate layer B1 has a thickness at which the magnetoresistive effect is easily detected, and the other intermediate layer B2 has a thickness at which the magnetoresistive effect is difficult to detect. In this case, the thickness range of the intermediate layer B1 is preferably 0.2 nm to 10 nm, and the thickness range of the intermediate layer B2 is preferably 3 nm to 50 nm.

  In this way, it is possible to mainly detect the magnetoresistive effect between the magnetic pinned layer C1 and the magnetic recording layer A with the intermediate layer B1 interposed therebetween, and it is easy to detect the magnetization M of the magnetic recording layer A. It becomes.

  FIG. 9B is a schematic cross-sectional view illustrating a third specific example of an asymmetric structure. That is, in this specific example, the electric resistances of the intermediate layers B1 and B2 are different from each other. For this purpose, methods such as making the materials and compositions of the intermediate layers B1 and B2 different from each other and adding an additive element to any one of the intermediate layers are effective.

  Furthermore, one of the intermediate layers B1 and B2 may be formed of a conductive material such as copper (Cu), and the other may be formed of an insulator. When the intermediate layer B1 (or B2) is formed of a thin insulator, a so-called tunneling magnetoresistance effect (TMR) can be obtained, and a large reproduction signal output can be obtained when reading the magnetization of the magnetic recording layer A. It becomes.

  FIG. 10 is a schematic cross-sectional view illustrating a fourth specific example of an asymmetric structure.

  That is, in this specific example, the intermediate material layer IE is inserted into the intermediate layer B2. This intermediate material layer IE is for increasing the magnetoresistance effect. Examples of the intermediate material layer IE include a discontinuous insulating thin film. That is, the magnetoresistive effect can be increased by inserting an insulating thin film having a pinhole or the like into the intermediate layer.

  Examples of such a discontinuous insulating thin film include an oxide or nitride of an alloy of nickel (Ni) and copper (Cu), an oxide or nitride of an alloy of nickel (Ni) and gold (Au), for example. And oxides or nitrides of alloys of aluminum (Al) and copper (Cu).

  Compounds such as oxides and nitrides of these alloys are phase-separated by being brought close to an equilibrium state by heating or the like, and are difficult to be compounded (such as oxidation and nitridation) such as Au and Cu. It separates into a compound phase that is easily oxidized and Al and has high electrical resistance. Therefore, by controlling the composition and temperature or applied energy, a discontinuous insulating thin film having pinholes can be formed. When a pinhole filled with a nonmagnetic material is formed in this way, the path through which current flows can be narrowed, and the spin-dependent scattering effect can be detected with high resistance, so that a large magnetoresistance effect is obtained.

  By inserting such an intermediate material layer IE into either of the intermediate layers B1 and B2, the magnetoresistive effect between the magnetic pinned layer and the magnetic recording layer on both sides thereof is increased, and detection becomes easy.

  FIG. 11 is a schematic cross-sectional view showing a fifth specific example of an asymmetric structure.

  That is, in this specific example, the intermediate layer B2 is an insulating layer having a pinhole PH. The pinhole PH is filled with the material of the magnetic pinned layer and the magnetic intermediate layer on both sides thereof.

  Thus, when the magnetic pinned layer C2 (or C1) and the magnetic recording layer A are connected via the pinhole PH, a so-called “magnetic point contact” is formed, and a very large magnetoresistance effect is obtained. Therefore, the direction of the magnetization M of the magnetic recording layer A can be easily determined by detecting the magnetoresistance effect between the magnetic layers on both sides via this pinhole PH.

  Here, it is desirable that the opening diameter of the pinhole PH is approximately 20 nm or less. Moreover, the shape of the pinhole PH can take various shapes such as a conical shape, a cylindrical shape, a spherical shape, a polygonal pyramid shape, and a polygonal columnar shape. Further, the number of pinholes PH may be one or plural. However, it is desirable to have fewer.

  The specific example of the asymmetric structure for easily reading the magnetization direction of the recording layer A by the magnetoresistive effect has been described above with reference to FIGS. These asymmetric structures are similarly applied to the perpendicular magnetization type magnetic cell shown in FIG.

  Next, a method for making the directions of the magnetizations M1 and M2 of the two magnetic pinned layers C1 and C2 antiparallel to each other in the magnetic cell of the present invention will be described.

  First, as a first method, a method of making the magnetizations M1 and M2 antiparallel by magnetostatically coupling the fixed layers C1 and C2 can be mentioned.

  FIG. 12 is a schematic cross-sectional view showing magnetostatic coupling of the pinned layers C1 and C2. That is, in this specific example, the magnetic yoke MY is provided on both side surfaces of the magnetic cell via the insulating layer IL. In the magnetic yoke MY, a magnetic field as indicated by an arrow is formed, and a recirculating magnetic field is formed via the magnetic yoke MY and the fixed layers C1 and C2. As described above, when the fixed layers C1 and C2 are magnetostatically coupled through the magnetic yoke MY, the magnetization M1 and the magnetization M2 can be made antiparallel by the circulating magnetic field.

  In this case, in order to set the directions of the magnetizations M1 and M2 of the pinned layer in advance, the magnetizations M1 and M2 can be set by changing the thickness of the two pinned layers C1 and C2 and applying a pulse magnetic field from the outside. The direction can be controlled.

  Further, the magnetization direction of the pinned layer can be controlled by forming an antiferromagnetic layer in contact with the outside of one pinned layer and imparting unidirectional anisotropy.

  FIG. 13 is a schematic cross-sectional view showing a magnetic cell provided with an antiferromagnetic layer. That is, the antiferromagnetic layer AF is provided under the pinned layer C2, and the direction of the magnetization M2 is fixed by magnetic coupling with the pinned layer C2. The magnetization M1 of the pinned layer C1 magnetostatically coupled to the pinned layer C2 via the magnetic yoke MY is in the opposite direction to the magnetization M2.

  Further, the magnetizations of the pinned layers C1 and C2 may be pinned by antiferromagnetic layers, respectively.

  FIG. 14 is a schematic cross-sectional view showing a magnetic cell in which the magnetizations of the pinned layers C1 and C2 are pinned by antiferromagnetic layers, respectively. That is, the antiferromagnetic layer AF1 is provided adjacent to the pinned layer C1, and the antiferromagnetic layer AF2 is provided adjacent to the pinned layer C2. The magnetizations M1 and M2 of the fixed layers are fixed antiparallel by the adjacent antiferromagnetic layers AF1 and AF2.

  Such a structure can be easily formed by appropriately selecting these materials so that the antiferromagnetic layers AF1 and AF2 have different blocking temperatures. That is, after forming the laminated structure shown in FIG. 14, heating is performed while applying a magnetic field. Thereafter, when cooled, the magnetization is first fixed in the antiferromagnetic layer having a high blocking temperature. Thereafter, when the magnetic field is reversed and further cooled, the magnetization is fixed in the antiferromagnetic layer having a low blocking temperature, and antiparallel magnetization is obtained.

  FIG. 15 is also a schematic diagram showing a magnetic cell in which the magnetizations of the pinned layers C1 and C2 are pinned by the antiferromagnetic layers. That is, in this specific example, the antiferromagnetic layer AF2 is provided outside the fixed layer C2, and the magnetic layer FM and the antiferromagnetic layer AF1 are provided outside the other fixed layer C1 via the nonmagnetic layer AC. Is provided.

  In this case, the nonmagnetic layer AC is set to a thickness such that the magnetic pinned layer C1 and the magnetic layer FM are antiferromagnetic interlayer exchange coupled. Further, as the material of the nonmagnetic layer AC, ruthenium (Ru), copper (Cu), or the like can be used.

  According to a process for imparting unidirectional anisotropy by a normal heat treatment in a magnetic field, the magnetic layers FM and C2 in contact with the two antiferromagnetic layers AF1 and AF2 have the same magnetization direction. Since the pinned layer C1 is antiferromagnetically coupled to the magnetic layer FM, the magnetization M1 is directed in the opposite direction, and as a result, the magnetization M1 and the magnetization M2 can be pinned antiparallel. Further, in this case, the magnetic layers FM and C2 in contact with the two antiferromagnetic layers AF1 and AF2 have the same magnetization direction, which has an advantage of facilitating the magnetization fixed formation process.

  In the case of this structure, it is desirable that the current I for writing to the recording layer A flows between the fixed layers C1 and C2, as shown by the arrow I1 (or the opposite direction) in FIG. However, from the viewpoint of use, it is represented by an arrow I2 (or the opposite direction) in FIG. 15 using electrodes (not shown) provided on the upper and lower portions of the antiferromagnetic layers AF1 and AF2, respectively. As described above, it is easier to pass the write current between the antiferromagnetic layers AF1 and AF2, and even if such a current is passed, the recording layer A can be written.

  FIG. 16 is a schematic cross-sectional view showing another specific example of a magnetic cell in which the magnetizations of the pinned layers C1 and C2 are pinned by an antiferromagnetic layer.

  That is, in this specific example, the magnetic layers FM1 and FM2 and the antiferromagnetic layers AF1 and AF2 are provided outside the magnetic pinned layers C1 and C2 via the nonmagnetic layers AC and FC. The nonmagnetic layer AC is adjusted so that antiferromagnetic interlayer exchange coupling occurs between the magnetic layers on both sides thereof. On the other hand, the nonmagnetic layer FC is adjusted so that ferromagnetic interlayer coupling occurs between the magnetic layers on both sides thereof.

In general, the interlayer exchange interaction through the nonmagnetic layer vibrates positively and negatively with respect to the film thickness of the nonmagnetic layer as schematically shown in FIG. Therefore, the film thicknesses of the nonmagnetic layers AC and FC may be set so as to correspond to two peak positions having different signs in FIG. For example, t 1 in FIG. 17 may be the film thickness of the nonmagnetic layer AC, and t 2 may be the film thickness of the nonmagnetic layer FC.

  With such a structure, by providing the unidirectional anisotropy by the antiferromagnetic layers AF1 and AF2, the magnetization arrangement of each of the magnetic layers FM1 and FM2 in contact with them is made the same direction, and finally the magnetic pinned layer The magnetization directions of C1 and C2 can be fixed antiparallel.

  Further, the magnetizations of the magnetic pinned layers C1 and C2 may be pinned by a hard magnet provided adjacent to them. Alternatively, a hard magnet may be used for the magnetic pinned layer C1 or C2 itself. As the hard magnet in this case, a magnetic material such as cobalt platinum (CoPt), iron platinum (FePt), cobalt chrome platinum (CoCrPt) can be used.

  In the case of the structure shown in FIG. 16 as well, the write current I to the recording layer A is allowed to flow between the fixed layers C1 and C2 as shown by the arrow I1 (or the opposite direction) in FIG. desirable. However, from the viewpoint of use, it is represented by an arrow I2 (or the opposite direction) using electrodes (not shown) provided on the upper and lower portions of the antiferromagnetic layers AF1 and AF2 in FIG. As described above, it is easier to pass the write current between the antiferromagnetic layers AF1 and AF2, and even if such a current is passed, the recording layer A can be written.

  As described above, the method for fixing the magnetizations M1 and M2 of the fixed layers C1 and C2 in antiparallel in the magnetic cell of the present invention has been described.

  The present invention can be applied not only to a single magnetic recording layer A but also to a plurality of magnetic recording layers A.

  FIG. 18 is a schematic cross-sectional view showing a magnetic cell provided with two magnetic recording layers. That is, in this magnetic cell, the magnetic pinned layer C1, the intermediate layer B1, the magnetic recording layer A1, the intermediate layer B2, the magnetic pinned layer C2, the intermediate layer B3, the magnetic recording layer A2, the intermediate layer B4, and the magnetic pinned layer C3 They are stacked in order. That is, the magnetic layer illustrated in FIG. 1 is formed in series above and below the fixed layer C2 so as to share the fixed layer C2. As described above, when the two recording layers A1 and A2 are stacked in series, the reproduction output signal can be increased.

  In FIG. 18, multi-value recording can be performed by changing the thickness and material of the two magnetic recording layers A1 and A2 so that the magnetization reversal currents of the magnetic recording layers A1 and A2 are different. Further, by stacking three or more magnetic recording layers in series, multi-value recording with more data types can be performed. The magnetization pinning of the pinned magnetic layer C2 is more effective if an antiferromagnetic layer is inserted inside the C2 layer to impart unidirectional anisotropy.

  In the present invention, the magnetic pinned layer C1 (or C2) can be a plurality of layers, or the magnetic recording layer A can be a plurality of layers. In particular, when a laminated film of antiferromagnetically coupled ferromagnetic layer / nonmagnetic layer / ferromagnetic layer is used as the magnetic pinned layer C1 (or C2), spin-dependent scattering between the interface and the layer is more emphasized. Therefore, the magnetization reversal of the magnetic recording layer A can be achieved with a smaller current.

  A specific example of this is the structure described above with reference to FIG. That is, in the figure, the laminated structure composed of the magnetic layer FM, the nonmagnetic layer AC, and the magnetic pinned layer C1 can be collectively referred to as “magnetic pinned structure P1”. In this case, as shown in the figure, when the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 in the magnetic pinned structure P1 is antiparallel to the magnetization direction of the magnetic pinned layer C2, the present invention The effect is obtained.

  FIG. 19 is a schematic cross-sectional view showing a specific example in which a magnetic pinned layer and a magnetic recording layer A are respectively laminated structures. That is, as the magnetic pinned structure P1, a laminated body composed of the magnetic layer FM / nonmagnetic layer AC / magnetic pinned layer C1 whose magnetizations are coupled in antiparallel is provided. Further, as the magnetic recording layer A, there is provided a laminate composed of an antiferromagnetically coupled magnetic layer A1 / nonmagnetic layer AC / magnetic layer A2 / nonmagnetic layer AC / magnetic layer A3. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 is antiparallel to the magnetization direction of the magnetic pinned layer C2, and among the magnetic recording layers A, the intermediate layer B1 and the intermediate layer B2 are separated from each other. The effects of the present invention can be obtained when the magnetizations of the magnetic layers A1 and A2 that are in contact with each other are parallel to each other.

  By making the magnetic recording layer A a laminated structure with antiferromagnetic coupling, the effective saturation magnetization of the magnetic recording layer can be lowered. That is, since the magnetization energy can be lowered, the magnetization reversal current, that is, the critical current required for writing can be lowered.

  In this structure, by providing the magnetic pinned structure P1, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the magnetic pinned layer C2) are parallel. It becomes. When the outer magnetic layer FM and the magnetic pinned layer C2 are pinned by an antiferromagnetic layer (not shown), the direction to be pinned is the same, so that there is an advantage that the formation process is easy.

  FIG. 20 is also a schematic cross-sectional view showing a specific example in which the magnetic pinned layer and the magnetic recording layer A are respectively laminated structures. That is, as the magnetic pinned structure P1, a laminated structure including a magnetic layer FM, a nonmagnetic layer AC, and a magnetic pinned layer C1 whose magnetizations are coupled in antiparallel is provided. Further, the magnetic recording layer A is provided with a laminated structure including a magnetically coupled magnetic layer A1 / nonmagnetic layer FC / magnetic layer A2. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 is antiparallel to the magnetization direction of the magnetic pinned layer C2 in contact with the intermediate layer B2, and the two magnetic layers A1 and A2 of the magnetic recording layer A The effects of the present invention can be obtained when the magnetizations of are parallel.

  When the magnetic recording layer A has a laminated structure in which the magnetic recording layer A is ferromagnetically coupled, the effective saturation magnetization of the magnetic recording layer can be lowered. That is, since the magnetization energy can be lowered, the magnetization reversal current, that is, the critical current required for writing can be lowered.

  Also in this structure, by providing the magnetic pinned structure P1, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the magnetic pinned layer C2) are parallel. It becomes. When the outer magnetic layer FM and the magnetic pinned layer C2 are pinned by an antiferromagnetic layer (not shown), the direction to be pinned is the same, so that there is an advantage that the forming process is easy.

  FIG. 21 is also a schematic cross-sectional view showing a specific example in which the magnetic pinned layer and the magnetic recording layer A are respectively laminated structures. That is, as the magnetic pinned structure P1, a laminated structure including a magnetic layer FM, a nonmagnetic layer AC, and a magnetic pinned layer C1 whose magnetizations are coupled in antiparallel is provided. Further, the magnetic recording layer A is provided with a laminated structure including a magnetic layer A1 / magnetic layer A2 / magnetic layer A3. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 is antiparallel to the magnetization direction of the magnetic pinned layer C2 in contact with the intermediate layer B2, and the magnetic recording layer A has three magnetic layers A1 to A3. The effects of the present invention can be obtained when the magnetizations of are parallel.

  When the magnetic recording layer A has a laminated structure in which the magnetic recording layer A is ferromagnetically coupled, permalloy or the like having a small saturation magnetization can be used for the central magnetic layer (A2), and the outer magnetic layers (A1, A3) can be made of CoFe or the like. In addition, since a material having a large spin asymmetry can be used, the magnetization reversal current can be lowered. In other words, the effect that the critical current value for writing can be lowered is obtained.

  Also in this structure, by providing the magnetic pinned structure P1, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the magnetic pinned layer C2) are parallel. It becomes. When the outer magnetic layer FM and the magnetic pinned layer C2 are pinned by an antiferromagnetic layer (not shown), the direction to be pinned is the same, so that there is an advantage that the formation process is easy.

  FIG. 22 is a schematic cross-sectional view showing a specific example in which two magnetic fixing structures are provided. That is, the magnetic pinned structure P1 is provided with a laminated structure composed of the magnetic layer FM / nonmagnetic layer AC / magnetic pinned layer C1 in which the magnetizations are coupled antiparallel, and the magnetic pinned structure P2 is coupled in a magnetization antiparallel. A laminated structure of the magnetic pinned layer C2 / nonmagnetic layer AC / magnetic layer FM / nonmagnetic layer AC / magnetic layer FM is provided. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 among the magnetic layers constituting the magnetic pinned structure P1, and the magnetic pinned layer in contact with the intermediate layer B2 among the magnetic layers constituting the magnetic pinned structure P2. The effect of the present invention is obtained when the magnetization direction of C2 is antiparallel.

  In this structure, the total number of magnetic layers constituting the magnetic pinned structures P1 and P2 is set to be even and odd, respectively. In this way, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the lowermost magnetic layer FM of the magnetic pinned structure P2) are parallel to each other. When the two outer magnetic layers FM are pinned by an antiferromagnetic layer (not shown), since the directions to be fixed are the same, there is an advantage that the formation process is easy.

  FIG. 23 is a schematic cross-sectional view showing a specific example in which the magnetic recording layer has a laminated structure as well as two magnetic fixing structures. That is, the magnetic pinned structure P1 is provided with a laminated structure composed of the magnetic layer FM / nonmagnetic layer AC / magnetic pinned layer C1 in which the magnetizations are coupled antiparallel, and the magnetic pinned structure P2 is coupled in a magnetization antiparallel. A laminated structure of the magnetic pinned layer C2 / nonmagnetic layer AC / magnetic layer FM / nonmagnetic layer AC / magnetic layer FM is provided. The magnetic recording layer A is provided with a laminated structure comprising an antiferromagnetically coupled magnetic layer A1 / nonmagnetic layer AC / magnetic layer A2 / nonmagnetic layer AC / magnetic layer A3. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 among the magnetic layers constituting the magnetic pinned laminate P1, and the magnetic pinned layer in contact with the intermediate layer B2 among the magnetic layers constituting the magnetic pinned structure P2. The effect of the present invention can be obtained when the magnetization direction of C2 is antiparallel and the magnetizations of the magnetic layers A1 and A3 in contact with the intermediate layer B1 and the intermediate layer B2 are parallel to the magnetic recording layer A, respectively. .

  Also in this structure, the total number of magnetic layers constituting the magnetic pinned structures P1 and P2 is set to be even and odd respectively for P1 and P2. In this way, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the lowermost magnetic layer FM of the magnetic pinned structure P2) are parallel to each other. When the two outer magnetic layers FM are pinned by an antiferromagnetic layer (not shown), since the directions to be fixed are the same, there is an advantage that the formation process is easy.

  FIG. 24 is also a schematic cross-sectional view showing a specific example in which the magnetic recording layer has a laminated structure as well as two magnetic fixing structures. That is, the magnetic pinned structure P1 is provided with a laminated structure composed of the magnetic layer FM / nonmagnetic layer AC / magnetic pinned layer C1 in which the magnetizations are antiparallelly coupled, and the magnetic pinned structure P2 is a magnetic layer in which the magnetizations are antiparallelly coupled. A laminated structure comprising a fixed layer C2 / nonmagnetic layer AC / magnetic layer FM / nonmagnetic layer AC / magnetic layer FM is provided. Further, the magnetic recording layer A is provided with a laminated structure comprising a ferromagnetically coupled magnetic layer A1 / nonmagnetic layer FC / magnetic layer A2. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 among the magnetic layers constituting the magnetic pinned structure P1, and the magnetic pinned layer in contact with the intermediate layer B2 among the magnetic layers constituting the magnetic pinned structure P2. The effect of the present invention can be obtained when the magnetization direction of C2 is antiparallel and the magnetic recording layer A has two magnetic layers A1 and A2 in parallel arrangement.

  Also in this structure, the total number of magnetic layers constituting the magnetic pinned structures P1 and P2 is set to be even and odd respectively for P1 and P2. In this way, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the lowermost magnetic layer FM of the magnetic pinned structure P2) are parallel to each other. When the two outer magnetic layers FM are pinned by an antiferromagnetic layer (not shown), since the directions to be fixed are the same, there is an advantage that the formation process is easy.

  FIG. 25 is also a schematic cross-sectional view showing a specific example in which the magnetic recording layer has a laminated structure as well as two magnetic fixing structures. That is, the magnetic pinned structure P1 is provided with a laminated structure composed of the magnetic layer FM / nonmagnetic layer AC / magnetic layer C1 in which the magnetizations are coupled antiparallel, and the magnetic pinned structure P2 is a magnetic layer in which the magnetizations are coupled antiparallel. A laminated structure of C2 / nonmagnetic layer AC / magnetic layer FM / nonmagnetic layer AC / magnetic layer FM is provided. Further, as the magnetic recording layer A, a laminated structure composed of a magnetic layer A1 / magnetic layer A2 / magnetic layer A3 is provided. In this structure, the magnetization direction of the magnetic pinned layer C1 in contact with the intermediate layer B1 among the magnetic layers constituting the magnetic pinned structure P1, and the magnetic pinned layer in contact with the intermediate layer B2 among the magnetic layers constituting the magnetic pinned structure P2. The effects of the present invention can be obtained when the magnetization direction of C2 is antiparallel and the magnetic recording layer A has the magnetizations of the three magnetic layers A1 to A3 being parallel.

  Also in this structure, the total number of magnetic layers constituting the magnetic pinned structures P1 and P2 is set to be even and odd respectively for P1 and P2. In this way, the magnetization directions of the two outermost magnetic layers (the uppermost magnetic layer FM of the magnetic pinned structure P1 and the lowermost magnetic layer FM of the magnetic pinned structure P2) are parallel to each other. When the two outer magnetic layers FM are pinned by an antiferromagnetic layer (not shown), since the directions to be fixed are the same, there is an advantage that the formation process is easy.

  As described above with reference to the specific example, by adopting a laminated structure in which the magnetic layers are antiferromagnetically coupled as the magnetic pinned structures P1 and P2, compared with the case where a single-layer film having the same thickness is used. The reversal current for reversing the magnetization of the magnetic recording layer can be reduced. Furthermore, by using a laminated structure with antiferromagnetic coupling, the leakage magnetic field can be reduced and problems such as crosstalk can be solved.

  In particular, the magnetic pinned layer far from the substrate is likely to generate a leakage magnetic field from the magnetic pole because the lateral dimension is reduced by fine processing. This magnetic bias due to the leakage magnetic field shifts the reversal current, and the reversal current becomes larger than when there is no magnetic field bias in either direction. On the other hand, if a magnetic pinned structure using a laminated film antiferromagnetically coupled is employed, the reversal current can be prevented from being shifted and the reversal current can be kept low in any direction.

  As described above, in the present invention, the magnetization control of the magnetic recording layer can be performed with a small current, and further the reading can be performed. Therefore, as will be described in detail later, by arranging a plurality of magnetic cells of the present invention, it is possible to realize a magnetic memory such as a probe storage or a solid-state memory with low power consumption and high reliability.

  Next, each element constituting the magnetic cell of the present invention will be described in detail.

First, the materials of the magnetic pinned layers C1 and C2 and the magnetic recording layer A are iron (Fe), cobalt (Co), nickel (Ni), or iron (Fe), cobalt (Co), nickel (Ni). An alloy containing at least one element selected from the group consisting of manganese (Mn) and chromium (Cr), a NiFe alloy called “permalloy”, a CoNbZr alloy, a FeTaC alloy, a CoTaZr alloy, and a FeAlSi alloy Soft magnetic materials such as alloys, FeB alloys, CoFeB alloys, Heusler alloys, magnetic semiconductors, half metal magnetic oxides such as CrO 2 , Fe 3 O 4 , La 1-X Sr X MnO 3 (or half metal magnetism) Any of (Nitride) can be used.

  Here, the “magnetic semiconductor” includes at least one magnetic element of iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), and manganese (Mn) and a compound semiconductor or an oxide semiconductor. Specifically, for example, (Ga, Cr) N, (Ga, Mn) N, MnAs, CrAs, (Ga, Cr) As, ZnO: Fe, (Mg, Fe) O And so on.

  In the present invention, the material of the magnetic pinned layers C1 and C2 and the magnetic recording layer A may be appropriately selected from those having magnetic characteristics according to the application. However, it is desirable to combine the materials of each layer so that the magnetoresistive effect via the intermediate layer B1 and the magnetoresistive effect via the intermediate layer B2 are both normal type or reverse type. These combinations will be described later.

  Further, the material used for these magnetic layers may be a continuous magnetic material, or a composite structure in which fine particles made of a magnetic material are deposited or formed in a nonmagnetic matrix. As such a composite structure, for example, a so-called “granular magnetic substance” can be cited.

  On the other hand, at least one of the magnetic pinned layers C1 and C2 may be a magnetic layer / nonmagnetic layer / magnetic layer, or a magnetic layer / nonmagnetic layer / magnetic layer / nonmagnetic layer / magnetic layer, or a magnetic layer / magnetic layer. In such a multilayer film, it is desirable that the magnetization direction of the magnetic layer in direct contact with the intermediate layer B1 (or B2) be antiparallel between the magnetic pinned layers C1 and C2.

  When the magnetic pinned layer C1 (or C2) is a laminated film of antiferromagnetically coupled ferromagnetic layer / nonmagnetic layer / ferromagnetic layer, the inventor of the present invention reversed the magnetization of the magnetic recording layer A with a smaller current. I found out that This is considered to be due to the spin-dependent scattering effect and reflection effect of the nonmagnetic layer exhibiting antiferromagnetic coupling. Further, by using such a three-layered film for the magnetic pinned layer C1 (or C2), a characteristic shift with respect to a magnetic field can be prevented.

  In the structure shown in FIG. 15 and the like, the ferromagnetic layer FM via the nonmagnetic layer AC is also fixed together with the magnetic fixed layer C2. Therefore, in the examples described later, these three-layer films may be collectively referred to as “magnetic pinned layers”.

  On the other hand, as a material of the magnetic recording layer A, a two-layer structure of [(Co or CoFe alloy) / (Permalloy alloy or Ni of NiFe or NiFeCo)] or [(Co or CoFe alloy) / (NiFe or NiFeCo It is also possible to use a three-layered laminate of Permalloy alloy or Ni) / (Co or CoFe alloy)]. In the case of a magnetic layer having such a multilayer structure, the thickness of the outer Co or CoFe alloy is preferably in the range of 0.2 nm to 1 nm. According to this structure, magnetization reversal can be obtained with a smaller current.

Further, the magnetic recording layer A may be configured as a multilayer film in which magnetic films are laminated. In this case, the magnetizations of the magnetic films constituting the multilayer film may all be aligned in one direction, or two intermediate layers B1 and B2 among the plurality of magnetic layers constituting the magnetic recording layer A. The magnetizations of the two outer magnetic layers in direct contact with each other may be parallel. When the magnetizations of the two outer magnetic layers that are in direct contact with the two intermediate layers B1 and B2 are antiparallel to each other, it is difficult to obtain the effects of the present invention.
In any case, if the easy magnetization axis of the magnetic recording layer A is parallel (or antiparallel) to the magnetization axes of the magnetizations M1 and M2 of the magnetic pinned layers C1 and C2, writing of magnetization to the magnetic recording layer A is performed. Is advantageous.

  On the other hand, the materials of the intermediate layers B1 and B2 include copper (Cu), gold (Au), silver (Ag), ruthenium (Ru) or an alloy containing one or more of these, aluminum (Al), An oxide or nitride containing at least one element selected from the group consisting of titanium (Ti), tantalum (Ta), cobalt (Co), nickel (Ni), silicon (Si) and iron (Fe); An insulator made of a compound can be used. In the case of the conductive layer, a different element such as oxygen may be added. Further, a high electrical resistance thin film in which different elements are discontinuous may be formed. Further, in the case of an insulating layer, a magnetic pinned layer hole may be formed, and the magnetic layer may enter there.

  Further, as the materials for the intermediate layers B1 and B2, it is desirable to use materials that can obtain a normal type magnetoresistive effect, or materials that can obtain a reverse type magnetoresistive effect. . Whether the magnetoresistive effect is the normal type or the reverse type is determined according to the combination of the material of the intermediate layer and the materials of the magnetic layers on both sides thereof.

  In the present invention, it is not desirable to use one in which either one is a normal type and the other is a reverse type. Here, as described above, the “normal type” means that the resistance increases when the magnetization directions of the magnetic layers provided on both sides of the intermediate layer are antiparallel. The “reverse type” means that the resistance decreases when the magnetization directions of the magnetic layers provided on both sides of the intermediate layer are antiparallel. The reason for this is as follows.

  That is, in the reverse type, spins in the opposite direction to the normal type contribute to conduction (including tunneling). For this reason, the resistance decreases when the magnetizations of the magnetic layers on both sides of the intermediate layer are antiparallel. However, when the antiparallel electrons contribute to the tunnel in this way, the writing direction is reversed from that in the normal type. Therefore, when a current is passed from the magnetic pinned layer C1 (or C2) toward the magnetic recording layer A, the magnetization of the magnetic recording layer A becomes antiparallel to the magnetization of the magnetic pinned layer C1 (or C2). When a current is passed from the magnetic recording layer A toward the magnetic pinned layer C1 (or C2), the magnetization of the magnetic recording layer A becomes parallel to the magnetization of the magnetic pinned layer C1 (or C2). For this reason, in the present invention, the effect cannot be obtained even if either one of the two intermediate layers B1 and B2 is a normal type and the other is a reverse type in combination with the magnetic layers on both sides. In other words, in the present invention, the magnetization of the magnetic pinned layers C1 and C2 at both ends is arranged in antiparallel, and the magnetic resistance effect via the intermediate layer B1 and the intermediate layer B2 are obtained by appropriately combining the materials of the magnetic layer and the intermediate layer. It is necessary to configure so that the magnetoresistive effect interposed between them is either a normal type or a reverse type.

  As described above, the materials of the intermediate layers B1 and B2 for obtaining the normal type magnetoresistance effect include copper (Cu), silver (Ag), gold (Au) and their compounds, alumina, and magnesium oxide. (MgO), aluminum nitride (Al—N), silicon oxynitride (Si—O—N), insulator with a hole filled with copper (Cu), insulation with a hole filled with a magnetic material The body can be mentioned.

  These materials are used as materials for the intermediate layers B1 and B2, and the magnetic pinned layers C1 and C2 disposed on both sides are used as the material for the magnetic recording layer A, such as Co, Fe, Ni, CoFe and NiFe, and Mn, By combining so-called metallic ferromagnets such as an alloy containing any of Cr, CoFeB, Heusler alloy, etc., between the magnetic pinned layer C1 and the magnetic recording layer A, and between the magnetic pinned layer C2 and the magnetic recording layer A, A normal type magnetoresistive effect can be obtained.

Also, when an oxide-based magnetic material such as CrO 2 , Fe 3 O 4 , La 1-X Sr X MnO 3 is used for the magnetic layer, the magnetic pinned layers C 1 and C 2 and the magnetic recording layer A are made of the same material The normal type magnetoresistance effect is obtained.

  Examples of the material of the intermediate layers B1 and B2 for obtaining the reverse type magnetoresistance effect include tantalum oxide (Ta—O). That is, when the above-described so-called metallic ferromagnet is used as the material of the magnetic pinned layers C1 and C2 and the magnetic recording layer A, a reverse type magnetoresistive effect can be obtained by combining with the tantalum oxide intermediate layers B1 and B2. can get.

Further, examples of the combination of magnetic layer / intermediate layer / magnetic layer that can provide a reverse type magnetoresistive effect include a combination of metal-based magnetic layer / oxide insulator intermediate layer / oxide-based magnetic layer. For example, Co / SrTiO 3 / La 0.7 Sr 0.3 MnO 3 , Co 9 Fe / SrTiO 3 / La 0.7 Sr 0.3 MnO 3 can be used.

Further, as a combination of magnetic layer / intermediate layer / magnetic layer capable of obtaining a reverse type magnetoresistive effect, magnetite / insulator intermediate such as Fe 3 O 4 / CoCr 2 O 4 / La 0.7 Sr 0.3 MnO 3 is used. Examples thereof include a layer / perovskite oxide magnetic material.

Still further, CrO 2 / Cr oxide insulator / Co can be cited as a combination of magnetic layer / intermediate layer / magnetic layer that provides a reverse type magnetoresistance effect.

  On the other hand, as the material of the antiferromagnetic layer AF for fixing the magnetization of the magnetic pinned layers C1 and C2, iron manganese (FeMn), platinum manganese (PtMn), palladium / manganese (PdMn), palladium platinum manganese (PdPtMn) It is desirable to use iridium manganese (IrMn), platinum iridium manganese (PtIrMn), or the like. In addition, as the nonmagnetic layer for fixing using interlayer coupling, copper (Cu), gold (Au), silver (Ag), ruthenium (Ru), or an alloy containing at least one of these is preferable.

  The thickness of the magnetic pinned layers C1 and C2 in the magnetic cell of the present invention is preferably in the range of 0.6 nm to 100 nm, and the thickness of the magnetic recording layer A is in the range of 0.2 nm to 50 nm. It is preferable. The thickness of the intermediate layers B1 and B2 is preferably in the range of 0.2 nm to 20 nm in the case of a conductor and in the range of 0.2 nm to 50 nm in the case of including an insulator.

As the planar shape of the magnetic cell of the present invention, the planar shape of the magnetic recording layer A is a rectangle, a vertically long (horizontal) hexagon, an ellipse, or a rhombus whose aspect ratio is in the range of 1: 1 to 1: 5. A parallelogram is preferable, and a uniaxial shape in which an edge domain is hard to be formed is desirable. However, in the case of a donut-shaped cell, it is preferable that the reflux magnetic domain is exceptionally easily formed. Further, it is desirable that the dimension of the magnetic recording layer A is in the range of about 5 nm to 1000 nm on one side in the longitudinal direction.
In FIG. 1 and the like, the magnetic pinned layers C1 and C2 and the magnetic recording layer A have the same dimension in the film surface direction, but the present invention is not limited to this. In other words, the layers of the magnetic cell may be formed so that the dimensions thereof are different from each other in order to connect wirings or control the magnetization direction. Further, the shapes may be different.

  As described above, the magnetic cell of the present invention can write magnetization in the magnetic recording layer A with a write current smaller than the spin-polarized current. Furthermore, the magnetization of the magnetic recording layer A can be read using the magnetoresistance effect. In addition, since the element is small in size, it has an advantage that it can be easily arrayed or integrated.

  Since the magnetic cell of the present invention is minute and has a magnetization reversal function, it can be applied to various applications. Next, a specific example in which the magnetic cells of the present invention are arranged and applied to a recording / reproducing apparatus will be described.

  FIG. 26 is a schematic diagram showing a magnetic memory using the magnetic cell of the present invention. That is, this example is a probe storage in which the magnetic cell of the present invention is applied to a so-called “patterned medium” and accessed by a probe.

  The recording medium has a structure in which the magnetic cells 10 of the present invention are arranged in a matrix on the conductive substrate 110 in the plane of the high-resistance insulator 100. In order to select these magnetic cells, a probe 200 is provided on the surface of the medium, a drive mechanism 210 for controlling the relative positional relationship between the probe 200 and the surface of the medium, and a current or voltage from the probe 200 to the magnetic cell 10. A power supply 220 for applying and a detection circuit 230 for detecting the internal magnetization state of the magnetic cell as a change in electrical resistance are provided.

  In the specific example shown in FIG. 26, the drive mechanism 210 is connected to the probe 200. However, since the relative position between the medium and the probe only needs to be changed, the drive mechanism 210 may be provided on the medium side. As shown in the figure, a plurality of magnetic cells 10 of the present invention are arranged on a conductive substrate 110 to form a patterned medium, and the magnetic cell 10 is interposed between the conductive probe 200 and the substrate 110. Recording / reproduction is performed by passing an electric current.

  In the specific example shown in FIG. 26, each cell 10 shares only the lower electrode in the substrate 110. However, as shown in FIG. 27, each cell 10 has a part of its layer. A shared structure may be used. With such a structure, the process can be simplified and the characteristics can be homogenized.

  Selection of the magnetic cell 10 is performed by changing the relative positional relationship between the conductive probe 200 and the patterned medium. The conductive probe 200 may be electrically connected to the magnetic cell 10 and may be in contact or non-contact. In the case of non-contact, recording / reproduction can be performed using a tunnel current flowing between the magnetic cell 10 and the probe 200 or a current generated by electric field radiation.

  Recording on the magnetic cell 10 is performed by a current flowing from the probe 200 accessing the magnetic cell to the magnetic cell 10 or a current flowing from the magnetic cell 10 to the probe 200. If the magnetization reversal current determined by the size, structure, composition, etc. of the magnetic cell 10 is Is, recording can be performed by passing a write current Iw larger than Is through the cell. The recorded magnetization direction is the same as the magnetization direction of the magnetic pinned layer that first passes when the electron current is used as a reference. Therefore, “0” or “1” can be appropriately written by reversing the flow of electrons, that is, the polarity of the current.

  The reproduction is performed by the current flowing from the probe 200 accessing the magnetic cell 10 or the current flowing to the probe as in the recording. However, at the time of reproduction, a reproduction current Ir smaller than the magnetization reversal current Is is passed. Then, the recording state of the magnetic recording layer A is determined by detecting the voltage or resistance. Therefore, in the magnetic memory of this specific example, recording / reproduction can be performed by supplying a current having a relationship of Iw> Ir.

  FIG. 28 is a schematic cross-sectional view showing a second specific example of a magnetic memory using the magnetic cell of the present invention.

  In other words, the magnetic memory of this example has a structure in which a plurality of magnetic cells 10 are arranged in parallel on an electrode layer (lower wiring) 110. Each magnetic cell 10 is electrically isolated by an insulator 100. Each magnetic cell 10 is connected to a wiring 120 generally called a bit line or a word line. A specific magnetic cell 10 can be selected by designating a bit line and a word line.

  Recording in the magnetic cell 10 is performed by a current flowing from the wiring 120 to the magnetic cell 10 or a current flowing from the magnetic cell 10 to the wiring 120. If the magnetization reversal current determined by the size, structure, composition, etc. of the magnetic cell 10 is Is, recording can be performed by passing a write current Iw larger than Is through the cell. The recorded magnetization direction is the same as the magnetization direction of the magnetic pinned layer that first passes through the electron current as a reference. Therefore, also in this case, “0” and “1” can be written by reversing the flow of electrons, that is, the polarity of the current.

  The reproduction is performed by a current that flows from or to the wiring that accesses the magnetic cell 10 as in the recording. However, during reproduction, a reproduction current Ir smaller than Is is passed. Then, the recording state is determined by detecting the voltage or resistance (current in the case of voltage application). Therefore, even in the magnetic memory of this specific example, recording / reproduction can be performed by supplying a current having a relationship of Iw> Ir.

  Hereinafter, embodiments of the present invention will be described in more detail with reference to examples.

(First embodiment)
FIG. 29A is a schematic diagram showing the cross-sectional structure of the main part of the magnetic cell of this example, and FIG. 29B is a schematic diagram showing the cross-sectional structure of the main part of the magnetic cell of the comparative example.

That is, the magnetic cell (sample I) of this example has a structure in which the electrode EL1, the magnetic pinned layer C1, the intermediate layer B1, the magnetic recording layer A, the intermediate layer B2, the magnetic pinned layer C2, and the electrode EL2 are stacked. The magnetic cell (sample II) of the comparative example has a structure in which the electrode EL1, the magnetic recording layer A, the intermediate layer B, the magnetic pinned layer C, and the electrode EL2 are stacked. The material and film thickness of each layer are as follows.

Sample I: EL1 (Cu) / C1 (Co: 20 nm) / B1 (Cu: 10 nm) / A (Co: 3 nm) / B2 (Cu: 6 nm) / C2 (Co: 20 nm) / EL2 (Cu)

Sample II: EL1 (Cu) / A (Co: 3 nm) / B (Cu: 6 nm) / C (Co: 20 nm) / EL2 (Cu)

These laminated structures were formed on the lower electrode EL2 by an ultrahigh vacuum sputtering apparatus. Further, after forming a tantalum (Ta) protective film (not shown) thereon, a resist was applied and a mask was formed by EB (electron beam) exposure, and then processed by ion milling. The processing size of the cell is 100 nm × 50 nm.

  For the obtained sample, the magnetization reversal current value of the magnetic recording layer A was determined from the change in resistance with respect to the amount of current flowing in the direction perpendicular to the film surface. As a result, the average value of the positive and negative reversal currents was 1.4 mA for sample I and 3.1 mA for sample II. In Sample II, asymmetry with respect to positive and negative currents was observed, but in Sample I, this asymmetry was resolved.

  That is, by providing the two magnetic pinned layers C1 and C2 whose magnetizations are antiparallel, the magnetization reversal current of the recording layer A is lowered and the symmetry of the write current is improved. The improvement in the symmetry of the write current is thought to be because the magnetic cell is magnetically more stable by providing the antiferromagnetic pinned layers C1 and C2 whose magnetization directions are antiparallel.

(Second embodiment)
Next, an embodiment of the magnetic cell having the structure shown in FIG. 15 will be described as a second embodiment of the present invention. In this example, a magnetic cell having a laminated structure in which the top and bottom of FIG.

  First, a lower electrode EL1 made of tantalum (Ta) and copper (Cu) is formed on a wafer using an ultra-high vacuum sputtering apparatus, and then PtMn 20 nm (antiferromagnetic layer AF1) and CoFe5 nm (magnetic layer) are formed thereon. FM), Ru1 nm (nonmagnetic layer AC), CoFe2 nm (magnetic pinned layer C1), Cu3 nm (intermediate layer B1), CoFe2 nm (magnetic recording layer A), Cu3 nm (intermediate layer B2), CoFe4 nm (magnetic pinned layer C2), PtMn20 nm (Antiferromagnetic layer AF2) was formed. Further, a laminated film made of copper (Cu) and tantalum (Ta) was formed thereon.

  This wafer was annealed in a magnetic field at 270 ° C. for 10 hours in a magnetic field vacuum furnace to impart unidirectional anisotropy. At this time, one of the wafers was taken out, and the hysteresis loop measurement of the applied magnetic field dependence of magnetization was performed with a vibrating sample magnetometer (VSM) to confirm the antiparallel magnetization fixation of C1 and C2. The film was coated with an EB resist and subjected to EB exposure, and then a mask having a predetermined shape was formed by lift-off. Next, the area | region which is not coat | covered with a mask was etched with the ion milling apparatus. Here, the amount of etching can be accurately grasped by introducing the sputtered particles into a quadrupole analyzer by working exhaust and performing mass analysis.

After etching, the mask was peeled off, and a SiO 2 film was formed, the surface was smoothed by ion milling, and a “heading” process was performed to expose the tantalum (Ta) surface. An upper electrode was formed on the tantalum surface. In this way, an element corresponding to FIG. 6 was produced.

  By the process described above, the magnetization directions of the magnetic pinned layers C1 and C2 arranged above and below the magnetic recording layer A can be pinned antiparallel.

(Third embodiment)
A magnetic cell having the structure shown in FIG. 16 was manufactured using the same process as in the second embodiment. However, also in this example, a magnetic cell having a laminated structure in which the top and bottom of FIG. The material and film thickness of each layer are as follows.

AF1 (PtMn: 20 nm) / FM1 (CoFe: 5 nm) / AC (Ru: 1 nm) / C1 (CoFe: 2 nm) / B1 (Cu: 3 nm) / A (CoFe: 2 nm) / B2 (Cu: 3 nm) / C2 (CoFe: 2 nm) / FC (Cu: 5 nm) / FM2 (CoFe: 5 nm) / AF2 (PtMn: 20 nm)

Also in this structure, the magnetization directions of the magnetic pinned layers C1 and C2 could be pinned antiparallel by the same process as described above with respect to the second embodiment.

(Fourth embodiment)
Next, as a fourth embodiment of the present invention, a sample group (sample II to sample V) is prepared in which asymmetry is imparted to the two intermediate layers B1 and B2 so that the magnetoresistive effect can be easily detected. The resistance change rate accompanying the current-driven magnetization reversal was evaluated together with a sample (sample I) in which the intermediate layer is symmetric, and a comparative study was performed. The structure of the central part of the magnetic cell of each sample is as follows.

Sample I: C1 (CoFe: 10 nm) / B1 (Cu: 8 nm) / A (CoFe: 3 nm) / B2 (Cu: 8 nm) / C2 (CoFe: 10 nm)

Sample II: C1 (CoFe: 10 nm) / B1 (Cu: 8 nm) / A (CoFe: 3 nm) / B2 (Cu: 4 nm) / C2 (CoFe: 10 nm)

Sample III: C1 (CoFe: 10 nm) / B1 (Cu: 8 nm) / A (CoFe: 3 nm) / B2 (Cu: 2 nm) / IE (Al—Cu—O: 0.6 nm) / B2 (Cu: 2 nm) / C2 (CoFe: 10 nm)

Sample IV: C1 (CoFe: 10 nm) / B1 (Cu: 8 nm) / A (CoFe: 3 nm) / B2 (Al 2 O 3 —CoFe: 3 nm) / C2 (CoFe: 10 nm)

Sample V: C1 (CoFe: 20 nm) / B1 (Cu: 8 nm) / A (CoFe: 3 nm) / B2 (Cu: 8 nm) / C2 (Co: 2 nm)

Here, sample I has a symmetrical intermediate layer B1, B2, sample II has an asymmetrical thickness of intermediate layer B1, B2 (FIG. 9 (a)), and sample III has a pole on one intermediate layer B2. A thin oxide layer (IE) was added (FIG. 10), and in Sample IV, one intermediate layer B2 deposited CoFe in alumina by co-evaporation of alumina and CoFe to form magnetic microcontacts. Sample (FIG. 11) and sample V have asymmetry in the thickness and composition of the magnetic pinned layers C1 and C2 (FIG. 8).

  In sample IV, annealing for lattice matching of the contact portion was performed. In addition, a PtMn layer / CoFe layer / Ru layer is provided on the lower side of each sample, and a PtMn layer is provided on the upper side. Fixed in parallel.

With respect to the obtained sample, the current was swept to determine the resistance change accompanying the magnetization reversal of the magnetic recording layer A. The results are as follows.

Sample number Resistance change rate
Sample I <0.1%
Sample II 0.4%
Sample III 5.0%
Sample IV 20%
Sample V 0.6%

From this result, it was found that the detection efficiency increases when the asymmetry is given, and the signal detection sensitivity increases especially when the asymmetry is given to the intermediate layers B1 and B2.

(Fifth embodiment)
Next, as a fifth embodiment of the present invention, magnetic cells having the same structure as the sample IV of the fourth embodiment are arranged on the substrate as shown in FIG. 26 to form a 32 × 32 matrix. . This matrix was further arranged in 32 × 32 to form a recording / reproducing medium having a total of 1 M (mega) bits. Then, a magnetic memory for recording / reproducing the recording / reproducing medium with 32 × 32 probes was manufactured. That is, in the magnetic memory of this example, one probe is associated with one set of matrices.

  Probing is as shown in FIG. The cell selection for each probe 200 was performed by an XY drive mechanism provided on the medium. However, if the positional relationship changes relatively, cell selection may be performed by the driving mechanism 210 provided in the probe 200. Since the probes 200 are multi-connected, each probe is connected to a so-called word line WL and a bit line BL, and the probe 200 can be selected by designating the word line WL and the bit line BL.

  Recording / reproduction to / from the magnetic cell 10 was performed by a current injected from the probe 200 accessing the magnetic cell. Here, by supplying a current of plus 1.2 mA and minus 1.2 mA, the “0” and “1” signals are written, respectively, and the cell voltage when reading a current of 0.5 mA or less is read for reproduction. The relationship was assigned to “0” and “1”. For comparison, writing was performed with a writing current of plus 0.5 mA and minus 0.5 mA, and reading was performed with a reproducing current of 0.4 mA or less. As a result, it was confirmed that writing was possible when the write current was set to plus 1.2 mA and minus 1.2 mA, but writing was not possible at plus 0.5 mA and minus 0.5 mA.

(Sixth embodiment)
Next, as a sixth embodiment of the present invention, an embodiment in which a magnetic memory is manufactured using a magnetic cell having the same structure as that of the sample III of the fourth embodiment will be described.

  First, a lower bit line and a transistor were formed on a wafer in advance, and a magnetic cell array was formed thereon using a method equivalent to the process described above with respect to the second embodiment. Further, a word line was formed thereon, and the magnetic memory having the structure shown in FIG. 31 in which the electrodes of the magnetic cells were connected to the bit line and the word line was formed.

  The magnetic cell 10 can be selected by designating the word line WL and the bit line BL connected to the magnetic cell. That is, by designating the bit line BL, the transistor TR is turned on, and a current flows through the magnetic cell 10 sandwiched between the word line WL and the electrode. At this time, if the magnetization reversal current determined by the size, structure, composition, etc. of the magnetic cell is Is, recording can be performed by passing a write current Iw larger than Is through the cell. Since the magnetic cell produced here has an average value of Is of 1.8 mA, the write current can be written with a current having a positive and negative polarity with a current exceeding this value. Also, the read current must not exceed 1.8 mA.

  In the fifth and sixth embodiments, the transistor TR is used for probe or cell selection, but other switching elements may be used. If possible, it is preferable that the on-resistance is low. A diode may be used.

(Seventh embodiment)
Next, as a seventh example of the present invention, the following sample was produced by changing the structure of the magnetic recording layer A of the sample I in the first example by the same production method as in the first example.

EL1 (Cu) / C1 (Co: 20 nm) / B1 (Cu: 10 nm) / A (Co: 0.6 nm) / A (Ni: 1.8 nm) / A (Co: 0.6 nm) / B2 (Cu: 6nm) / C2 (Co: 20nm) / EL2 (Cu)

That is, as the magnetic recording layer A, a laminated structure of Co (0.6 nm) / Ni (1.8 nm) / Co (0.6 nm) was employed. When the magnetization reversal characteristics of this sample were evaluated, the reversal current was 1.1 mA, and the reversal current was further reduced as compared with Sample I of the first example. This is presumably because the magnetic energy of the magnetic recording layer A has decreased.

(Eighth embodiment)
Next, as an eighth embodiment of the present invention, a magnetic cell having the structure shown in FIG. 15 was prepared. First, two types of magnetic cells (sample A10 and sample B10) created in this example will be described.

In sample A10, PtMn (20 nm) is formed as an antiferromagnetic layer AF2 on a lower electrode (not shown), and Co 9 Fe 1 (20 nm) is formed as a magnetic pinned layer C2 thereon, and Cu ( 4 nm), Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, Ru (1 nm) as the nonmagnetic layer AC, Co 9 Fe 1 (4 nm) is laminated as the magnetic layer FM, PtMn (15 nm) is formed thereon as the antiferromagnetic layer AF1, and an “anti-parallel dual pin structure” is formed. . In this structure, the magnetoresistive effect (MR) via the two intermediate layers B1 and B2 is a normal type MR. Three element sizes of 60 nm × 110 nm, 80 nm × 165 nm, and 110 nm × 240 nm were prepared.

On the other hand, in the sample B10, PtMn (20 nm) is formed as the antiferromagnetic layer AF2 on the lower electrode (not shown), and Co 9 Fe 1 (10 nm) is formed as the magnetic pinned layer C2 and the intermediate layer B2 is formed thereon. Al 2 O 3 (0.8 nm), Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, nonmagnetic Ru (1 nm) is stacked as the layer AC, Co 9 Fe 1 (4 nm) is stacked as the magnetic layer FM, PtMn (15 nm) is formed as the antiferromagnetic layer AF1, and an upper electrode (not shown) is further formed. .

  In the structure of the sample B10, the materials of the two intermediate layers B1 and B2 are different, but it was confirmed in advance that both MRs through the intermediate layers B1 and B2 show normal type MR. The element sizes were the same as in sample A10.

Sample A10 was produced as follows.
First, after the lower electrode is formed on the wafer, the wafer is introduced into an ultra-high vacuum sputtering apparatus, and after the surface is sputter-cleaned, PtMn (20 nm) / Co 9 Fe 1 (20 nm) / Cu (4 nm) / A multilayer film of Co 9 Fe 1 (2.5 nm) / Cu (6 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) is deposited and I took it out.

  Next, the wafer was put into a vacuum magnetic field furnace, annealed in a magnetic field at 270 ° C. for 10 hours, and an exchange bias was applied to the fixed layers C1 and C2. Next, a resist was applied and electron beam exposure was performed with an EB (electron beam) drawing apparatus, and then a mask pattern corresponding to the element size described above was formed. This pattern was milled to the upper part of the magnetic pinned layer C2 by an ion milling device to form an element.

The element shape was set so that the longitudinal axis direction of the element was parallel to the exchange bias direction of the magnetic pinned layers C1 and C2. Then, SiO 2 was embedded around this element, and the upper electrode was formed to complete the magnetic cell.

Sample B10 was produced as follows.
First, after forming a lower electrode on a wafer, the wafer was introduced into an ultrahigh vacuum sputtering apparatus, and a multilayer film composed of PtMn (20 nm) / CoFe (10 nm) / Al was first deposited. Next, oxygen was introduced into the sputtering apparatus to oxidize aluminum (Al) to form Al 2 O 3 . Here, aluminum oxide having a composition in which oxygen is slightly lost may be formed instead of Al 2 O 3 . The same applies to the other embodiments described in this specification.

On this Al 2 O 3 , Co 9 Fe 1 (2.5 nm) / Cu (6 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) ) Was deposited and removed from the apparatus.

Next, a resist was applied and electron beam exposure was performed with an EB drawing apparatus, and then a mask pattern corresponding to the element size described above was formed. Then, to form the elements by milling to the top of the Al 2 O 3 by ion milling device. The element was formed such that the longitudinal axis direction thereof was parallel to the exchange bias direction of the magnetic pinned layers C1 and C2. Then, SiO 2 was embedded around the element, and the upper electrode was formed to complete the magnetic cell.

  Further, Sample C10, Sample D10, Sample E10, and Sample F10 were prepared for comparison. These structures are as follows.

Sample C10 has PtMn (20 nm) as the antiferromagnetic layer AF2, Co 9 Fe 1 (10 nm) as the magnetic pinned layer C2, TaO1.4 (1 nm) as the intermediate layer B2, and the magnetic recording layer A on the lower electrode. Co 9 Fe 1 (2.5 nm) as the intermediate layer B1, Cu (6 nm) as the magnetic pinned layer C1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, Ru (1 nm) as the nonmagnetic layer AC, and Co 9 Fe as the magnetic layer FM 1 (4 nm), PtMn (15 nm) is laminated in this order as the antiferromagnetic layer AF, and an upper electrode is formed. In this structure, it was confirmed in advance that TaO1.4 of the intermediate layer B2 indicates a reverse type MR, and Cu of the intermediate layer B1 indicates a normal type MR. For this reason, this structure is unsuitable for the magnetic cell of the present invention.

Sample D10 has PtMn (20 nm) as an antiferromagnetic layer, Co 9 Fe 1 (20 nm) as a magnetic pinned layer, Cu (4 nm) as an intermediate layer, and Co 9 Fe 1 (as a magnetic recording layer) on the lower electrode. 2.5 nm) and has a single pin structure in which the upper electrode is stacked in this order.

Sample E10 has PtMn (20 nm) as an antiferromagnetic layer, Co 9 Fe 1 (20 nm) as a magnetic pinned layer, Al 2 O 3 (0.8 nm) as an intermediate layer, and a magnetic recording layer on the lower electrode. As Co 9 Fe 1 (2.5 nm), and the upper electrode has a single pin structure laminated in this order.

Sample F10 has Co 9 Fe 1 (2.5 nm) as the magnetic recording layer, Cu (6 nm) as the intermediate layer, Co 9 Fe 1 (4 nm) as the magnetic pinned layer, and Ru as the nonmagnetic layer on the lower electrode. (1 nm), Co 9 Fe 1 (4 nm) as a magnetic layer, PtMn (15 nm) as an antiferromagnetic layer, and an upper electrode are stacked in this order.

  With respect to the sample A10 having a size of 60 nm × 110 nm and the sample B10 having a size of 60 nm × 110 nm, a current was allowed to flow between plus and minus 10 mA between the upper electrode and the lower electrode, and the current dependency of the differential resistance was measured.

FIG. 32 is a graph showing the differential resistance of sample A10.
FIG. 33 is a graph showing the differential resistance of sample B10.

  The polarity of the current is defined so that the current becomes positive when the flow of electrons flows from the magnetic pinned layer C2 to the magnetic pinned layer C1. In the case of sample A10 (FIG. 32), a downward convex curve was obtained, and in the case of sample B10 (FIG. 33), an upward convex curve was obtained. In both the sample A10 and the sample B10, a high resistance state and a low resistance state appear due to a change in current. From this result, it can be seen that the magnetization of the magnetic recording layer A is reversed by the polarity of the current flowing in the magnetic cell, and the signal can be written.

  FIG. 34 is a graph showing the differential resistance change normalized by the differential resistance in the low resistance state after removing the background curve component in FIGS. 32 and 33. FIG. 34 also shows the results of the samples D10, E10, and F10 having the same size. From the figure, it can be seen that samples A10 and B10 have a very small current for magnetization reversal compared to the other samples. For sample C10, no magnetization reversal was observed at a current of plus or minus 10 mA. That is, it was found that the magnetization reversal current of sample C10 was larger than 10 mA.

  From the above results, it can be seen that Samples A10 and B10 have a lower critical current (Ic) for magnetization reversal than Samples C10, D10, E10, and F10, and can be written with a low current.

  FIG. 35 is a graph showing the relationship between the average value of the magnetization reversal critical current Ic and the cell size. Here, the average value of the critical current Ic is the average of the critical current Ic + when recording from the high resistance state to the low resistance state in FIG. 32 and the critical current Ic− when recording from the low resistance state to the high resistance state. It is the value.

  In any sample, the critical current Ic is substantially proportional to the cell size. It can be seen that the samples A10 and B10 can be recorded with a lower current density than the samples D10, E10, and F10.

  From the results described above, it was confirmed that writing was possible with low power consumption according to the structure shown in FIG.

It should be noted that SiO 2 or Al in which MgO, SiO 2 , Si—O—N, holes are formed in the intermediate layer B2 of sample B10 and a magnetic material or conductive metal (Cu, Ag, Au) is embedded in the holes. It was confirmed that the same tendency as above was obtained when 2 O 3 was used.

(Ninth embodiment)
Next, as a ninth embodiment of the present invention, magnetic cells (samples A20 and B20) having the structure shown in FIGS. 19 and 20 were prepared.

In sample A20 (FIG. 19), PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (20 nm) as the magnetic pinned layer C2, Al 2 O 3 (0.8 nm) as the intermediate layer B2, and the magnetic layer A3 As Co 9 Fe 1 (1 nm), as the nonmagnetic layer AC Ru (1 nm), as the magnetic layer A2 Co 9 Fe 1 (1 nm), as the nonmagnetic layer AC Ru (1 nm), and as the magnetic layer A1 Co 9 Fe 1 ( 1 nm), Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, Ru (1 nm) as the nonmagnetic layer AC, and Co 9 Fe 1 (4 nm) as the magnetic layer FM, It has a structure in which PtMn (15 nm) and an upper electrode are formed thereon. That is, sample A20 has an antiparallel dual pin structure. Three element sizes of 60 nm × 110 nm, 80 nm × 165 nm, and 110 nm × 240 nm were prepared.

On the other hand, sample B20 (FIG. 20) has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (20 nm) as the magnetic pinned layer C2, Cu (4 nm) as the intermediate layer B2, and Co 9 as the magnetic layer A2. Fe 1 (1.25 nm), Cu (0.3 nm) as the nonmagnetic layer FC, Co 9 Fe 1 (1.25 nm) as the magnetic layer A1, Cu (6 nm) as the intermediate layer B1, and Co 9 as the magnetic pinned layer C1. Fe 1 (4 nm), Ru (1 nm) as the nonmagnetic layer AC, Co 9 Fe 1 (4 nm) as the magnetic layer FM are stacked, and PtMn (15 nm) and an upper electrode are formed thereon. That is, the sample B20 also has an antiparallel dual pin structure. The element size of B20 was the same as that of sample A20.

Sample A20 was produced as follows.
First, after forming a lower electrode on a wafer, the wafer was introduced into an ultrahigh vacuum sputtering apparatus, and first, PtMn (20 nm) / Co 9 Fe 1 (20 nm) / Al was deposited. Next, oxygen plasma was generated in the sputtering apparatus to oxidize Al to form Al 2 O 3 . On top of this Al 2 O 3 , Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm) / Cu (6 nm) / Co A 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) multilayer film was laminated and taken out from the apparatus.

Next, a resist was applied and electron beam exposure was performed with an EB drawing apparatus, and then a mask pattern corresponding to the above element size was formed. Next, the element was formed by milling to the upper part of Al 2 O 3 with an ion milling device. The element was formed such that its longitudinal axis direction was parallel to the exchange bias direction of the magnetic pinned layer. Next, SiO 2 was embedded around the element, and the upper electrode was formed to complete the magnetic cell.

Sample B20 was produced in the same manner as Sample A20.
For comparison, Samples C20, D20, and E20 were prepared.
FIG. 36 is a schematic diagram showing a cross-sectional structure of sample C20.
Sample C20 has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (20 nm) as the magnetic pinned layer C2, Al 2 O 3 (0.8 nm) as the intermediate layer B2, and Co 9 Fe as the magnetic layer A2. 1 (1 nm), Ru (1 nm) as the nonmagnetic layer AC, Co 9 Fe 1 (1 nm) as the magnetic layer A1, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, Ru (1 nm) as the magnetic layer AC and Co 9 Fe 1 (4 nm) as the magnetic layer FM are stacked in this order, and PtMn (15 nm) and an upper electrode are formed thereon.

  That is, the sample C20 has an antiparallel dual pin structure, but the magnetizations of the magnetic layer A1 and the magnetic layer A2 in contact with the two intermediate layers B1 and B2 are antiparallel to each other, which is inappropriate for the magnetic cell of the present invention. It is.

Sample D20 has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (20 nm) as the magnetic pinned layer C1, Al 2 O 3 (0.7 nm) as the intermediate layer B2, and Co 9 Fe as the magnetic layer A3. 1 (1nm), Ru (1nm ) as the non-magnetic layer AC, Co 9 Fe 1 as the magnetic layer A2 (1nm), Ru (1nm ) as the non-magnetic layer AC, Co 9 Fe 1 as the magnetic layer A1 is (1 nm) layered And an upper electrode is formed thereon. That is, the sample D20 has a single pin structure.

Sample E20 has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (20 nm) as the magnetic pinned layer C1, Cu (4 nm) as the intermediate layer B2, and Co 9 Fe 1 (1.25 nm as the magnetic layer A2). ), Cu (0.3 nm) as the nonmagnetic layer FC, Co 9 Fe 1 (1.25 nm) as the magnetic layer A1, and a single pin structure in which the upper electrode is formed thereon.

  FIG. 37 is a graph showing the current dependence of the differential resistance change for samples A20, B20, D20, and E20 having a size of 60 nm × 110 nm. From the figure, it can be seen that Samples A20 and B20 of the present invention have a smaller magnetization reversal current than Comparative Samples D20 and E20. In sample C20, since the cell was electrically destroyed before the magnetizations of the magnetic layers A1 and A2 were reversed, no magnetization reversal was observed.

  From the above results, it can be seen that Samples A20 and B20 have a lower critical current Ic for magnetization reversal than Samples C20, D20 and E20, and can be written with a low current.

  FIG. 38 is a graph showing the relationship between the average value of the critical current Ic and the cell size. All of the elements are substantially proportional to the area, and it can be seen that the samples A20 and B20 can be recorded at a lower current density than the samples D20 and E20.

  From the above results, it was confirmed that the structure shown in FIGS. 19 and 20 is suitable for a magnetic cell capable of writing with low power consumption.

As the intermediate layer B2 between the sample A20 and the sample B20, SiO in which MgO, SiO 2 , Si—O—N, holes are formed and a magnetic material or conductive metal (Cu, Ag, Au) is embedded in the holes is provided. It was found that the same tendency as above was obtained when 2 or Al 2 O 3 was used.

(Tenth embodiment)
Next, magnetic cells (samples A30 and B30) having the structure shown in FIG. 22 were prepared as a tenth example of the present invention.

Sample A30 has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (4 nm) as the magnetic layer FM, Ru (1 nm) as the nonmagnetic layer AC, Co 9 Fe 1 (4 nm) as the magnetic layer FM, Ru (1 nm) as the nonmagnetic layer AC, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C2, Cu (3 nm) as the intermediate layer B2, Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, and the intermediate layer B1 Cu (6nm), Co 9 Fe 1 as magnetic fixed layer C1 (4 nm) as, Ru (1 nm) as the non-magnetic layer AC, Co 9 Fe 1 (4nm ) is laminated as a magnetic layer FM, PtMn (15 nm thereon ) And the upper electrode is formed. That is, the sample A30 has an antiparallel dual pin structure. Three element sizes of 60 nm × 110 nm, 80 nm × 165 nm, and 110 nm × 240 nm were prepared.

On the other hand, sample B30 has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (4 nm) as the magnetic layer FM, Ru (1 nm) as the nonmagnetic layer AC, and Co 9 Fe 1 (4 nm as the magnetic layer FM). ) Ru (1 nm) as nonmagnetic layer AC, Co 9 Fe 1 (4 nm) as magnetic pinned layer C2, Cu (6 nm) as intermediate layer B2, Co 9 Fe 1 (2.5 nm) as magnetic recording layer A, intermediate layer Al 2 O 3 (0.8 nm) as B1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, Ru (1 nm) as the nonmagnetic layer AC, and Co 9 Fe 1 (4 nm) as the magnetic layer FM are stacked in this order. And PtMn (15 nm) and an upper electrode are formed thereon. That is, the sample B30 also has an antiparallel dual pin structure. The element size of sample B30 was the same as that of sample A30. In the case of sample B30, the materials of the two intermediate layers B1 and B2 are different, but in each case, the MR via the intermediate layer is a normal type MR.

Sample A30 was produced as follows.
First, an SiO 2 layer and a Ta layer were grown in this order on the lower electrode. A resist was applied thereon, and a mask pattern was drawn with an EB drawing apparatus. Next, the resist in the pattern portion was removed, and holes corresponding to the element size were formed in the Ta layer by ion milling. Furthermore, a hole having an area slightly larger than the element size was formed in the SiO 2 layer below the Ta layer by reactive ion etching to expose the surface of the lower electrode.

After introducing this wafer into an ultra-high vacuum sputtering apparatus, evacuating and cleaning the surface by etching, Ru / PtMn (20 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 ( 4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Cu (3 nm) / Co 9 Fe 1 (2.5 nm) / Cu (6 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) was grown in this order. Further, an upper electrode was formed thereon. This wafer was put into a vacuum magnetic field furnace and annealed in a magnetic field at 270 ° C. for 12 hours to introduce an exchange bias into the magnetic pinned layer. At that time, the direction of the exchange bias was made parallel to the longitudinal direction of the element.

Sample B30 was produced as follows.
First, a SiO 2 layer and a Ta layer were grown in this order on the lower electrode. A resist was applied thereon, and a mask pattern was drawn with an EB drawing apparatus. Next, the resist of this pattern portion was removed, and holes corresponding to the element size were formed in the Ta layer by ion milling. Furthermore, a hole having an area slightly larger than the element size was made in the SiO 2 layer under the Ta layer by reactive ion etching to expose the surface of the lower electrode.

The wafer was introduced into an ultra-high vacuum sputtering apparatus, evacuated, and surface-cleaned by surface etching, and then Ru / PtMn (20 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 ( 4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Cu (6 nm) / Co 9 Fe 1 (2.5 nm) / Al. At this stage, oxygen was introduced into the chamber to oxidize the aluminum, and then evacuated again to an ultra-high vacuum. The remaining Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) was deposited in this order. Further, an upper electrode was formed. This wafer was put into a vacuum magnetic field furnace and annealed in a magnetic field at 270 ° C. for 12 hours to introduce an exchange bias into the magnetic pinned layer. At that time, the direction of the exchange bias was made parallel to the longitudinal direction of the element.

  Furthermore, Sample C30, Sample D30, and Sample E30 were prepared for comparison.

Sample C30 has PtMn (20 nm) on the lower electrode and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe as the magnetic pinned structure P2. 1 (4 nm), Cu (6 nm) as the intermediate layer B2, Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, TaO (1 nm) as the intermediate layer B1, and Co 9 Fe 1 (as the magnetic pinned structure P1). 4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) are laminated in this order, and PtMn (15 nm) and an upper electrode are laminated thereon. This structure is an antiparallel dual pin structure. However, Cu in the intermediate layer B2 exhibits a normal type MR, whereas TaO in the intermediate layer B1 exhibits a reverse type MR, which is a comparative sample that does not conform to the present invention.

Sample D30 has PtMn (20 nm) on the lower electrode and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 as the magnetic pinned layer structure P2. Fe 1 (4 nm), Cu (3 nm) as an intermediate layer, Co 9 Fe 1 (2.5 nm) as a magnetic recording layer A, and a single pin structure having an upper electrode thereon.

Sample E30 has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe as the magnetic pinned structure P2. 1 (4 nm), Al 2 O 3 (0.8 nm) as an intermediate layer, Co 9 Fe 1 (2.5 nm) as a magnetic recording layer A, and a single pin structure having an upper electrode thereon.

  FIG. 39 is a graph showing the relationship between the differential resistance change and the current for samples A30, B30, D30, and E30. Here, the size of the sample is 60 nm × 110 nm. In sample C30, no magnetization reversal was observed because the magnetic cell was electrically destroyed before the magnetization of the magnetic recording layer A was reversed.

  From the above results, it can be seen that Samples A30 and B30 have a lower critical current Ic for magnetization reversal than Samples C30, D30 and E30, and can be written with a low current.

  FIG. 40 is a graph showing the relationship between the average value of the critical current Ic and the cell size. In any sample, the critical current Ic is substantially proportional to the cell area, and it can be seen that the samples A30 and B30 can be recorded at a lower current density than the samples D30 and E30.

  As described above, it was confirmed that the structure shown in FIG. 22 is suitable for a magnetic cell capable of writing with low power consumption.

As the intermediate layer B1 of the sample A30, SiO 2 or Al in which MgO, SiO 2 , Si—O—N, holes are formed and a magnetic material or conductive metal (Cu, Ag, Au) is embedded in the holes. It has been found that the same tendency as described above can be obtained when 2 O 3 is used.

(Eleventh embodiment)
Next, as eleventh embodiment of the present invention, magnetic cells (samples A40 and B40) having the structure shown in FIGS. 23 and 24 were prepared.
Sample A40 (FIG. 23) has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) as the magnetic pinned layer structure P2. ) / Co 9 Fe 1 (4 nm), Cu (5 nm) as the intermediate layer B 2, Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm), Cu (10 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm), PtMn (15 nm), upper electrode as the magnetic pinned structure P1 Have a structure formed in this order. That is, the sample A40 has an antiparallel dual pin structure. Three element sizes were prepared: 60 nm × 110 nm, 80 nm × 165 nm, and 110 nm × 240 nm.

On the other hand, sample B40 has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co as the magnetic pinned structure P2. 9 Fe 1 (4 nm), Al 2 O 3 (0.8 nm) as the intermediate layer B2, and Co 9 Fe 1 (1.25 nm) / Cu (0.3 nm) / Co 9 Fe 1 (1 as the magnetic recording layer A .25 nm), Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm), PtMn (15 nm), and the upper electrode are formed in this order as the magnetic pinned structure P1. Has a structured. That is, the sample B40 also has an antiparallel dual pin structure. In this structure, the materials of the two intermediate layers B1 and B2 are different. In either case, the MR via the intermediate layer is a normal type MR. The element size was the same as A40.

  Sample A40 was produced by the same method as A10 described above. Sample B40 was produced by the same method as Sample B10 described above.

Furthermore, samples C40, D40, and E40 were prepared for comparison.
Sample C40 has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe as the magnetic pinned structure P2. 1 (4 nm), Cu (5 nm) as the intermediate layer B2, Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm) as the magnetic recording layer A, and Cu (10 nm) as the intermediate layer B1, As the magnetic pinned structure P1, Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm), PtMn (15 nm), and an upper electrode are formed in this order. This structure is an antiparallel dual pin structure, but the magnetizations of the magnetic layers constituting the magnetic recording layer A in contact with the two intermediate layers B1 and B2 are antiparallel to each other, which is different from that of the present invention.

In the sample D40, PtMn (20 nm) is formed on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 is used as the magnetic fixed structure. (4 nm), Cu (6 nm) as the intermediate layer B2, and Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm) / Ru (1 nm) / Co 9 Fe 1 (1 nm) as the magnetic recording layer A ) Are stacked, and an upper electrode is formed thereon.

In the sample E40, PtMn (20 nm) is formed on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (Co 9 Fe 1 ( 4 nm), Al 2 O 3 (0.7 nm) as the intermediate layer, Co 9 Fe 1 (1.25 nm) / Cu (0.3 nm) / Co 9 Fe 1 (1.25 nm) as the magnetic recording layer A, upper electrode Has a single pin structure.

  FIG. 41 is a graph showing the relationship between differential resistance change and current for samples A40, B40, D40, and E40. Here, the size of the cell is 60 nm × 110 nm. From FIG. 41, it can be seen that the current at which the magnetizations of the samples A40 and B40 are reversed is much smaller than that of the samples D40 and E40. For sample C40, the cell was electrically destroyed before the magnetization of the magnetic recording layer A was reversed, so no magnetization reversal was observed.

  From the above results, it can be seen that Samples A40 and B40 have a lower critical current Ic for magnetization reversal than Samples C40, D40 and E40, and can be written with a low current.

  FIG. 42 is a graph showing the relationship between the average value of the critical current Ic and the cell size. In any sample, it can be seen that the critical current Ic is approximately proportional to the cell size. It can also be seen that the samples A40 and B40 can be recorded with a lower current density than the samples D40 and E40.

  As described above, it has been confirmed that the structure shown in FIGS. 23 and 24 is suitable for a magnetic cell capable of writing with low power consumption.

In addition, as a material of the intermediate layer B2 of the sample A40 and the sample B40, MgO, SiO 2 , Si—O—N, holes are formed, and the magnetic material or conductive metal (Cu, Ag, Au) is embedded in the holes. It was also found that the same tendency as described above was obtained when SiO 2 or Al 2 O 3 was used.

(Twelfth embodiment)
Next, as a twelfth embodiment of the present invention, magnetic cells (samples A50 and B50) having the structure shown in FIGS. 21 and 25 were prepared.
Sample A50 (FIG. 21) has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (20 nm) as the magnetic pinned layer C2, Cu (6 nm) as the intermediate layer B2, and Co 9 Fe as the magnetic recording layer A. 1 (0.8 nm) / NiFe (0.8 nm) / Co 9 Fe 1 (0.8 nm), Al 2 O 3 (1.0 nm) as the intermediate layer B1, and Co 9 Fe 1 (4 nm) as the magnetic pinned structure P1 / Ru (1 nm) / Co 9 Fe 1 (4 nm), PtMn (15 nm), and an upper electrode are formed. That is, sample A50 also has an antiparallel dual pin structure.
Three element sizes were prepared: 60 nm × 110 nm, 80 nm × 165 nm, and 110 nm × 240 nm.

On the other hand, sample B50 has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co as the magnetic pinned structure P2. 9 Fe 1 (4 nm), Cu (6 nm) as the intermediate layer B2, Co 9 Fe 1 (0.8 nm) / NiFe (0.8 nm) / Co 9 Fe 1 (0.8 nm) as the magnetic recording layer A, intermediate layer B1 is Cu (9 nm), the magnetic pinned structure P1 is Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm), PtMn (15 nm), and the upper electrode is formed in this order. That is, the sample B50 also has an antiparallel dual pin structure. The element size was the same as A50.
In the sample A50, the materials of the two intermediate layers B1 and B2 are different, but the MR via these intermediate layers is a normal type MR.

Sample A50 was produced as follows.
First, an SiO 2 layer and a Ta layer were grown in this order on the lower electrode. A resist was applied thereon, and a mask pattern was drawn with an EB drawing apparatus. Next, the resist in the pattern portion was removed, and holes corresponding to the element size were formed in the Ta layer by ion milling. Further, a hole having an area slightly larger than the element size was formed in the SiO 2 layer under the Ta layer by reactive ion etching to expose the lower electrode surface.

Next, after introducing this wafer into an ultra-high vacuum sputtering apparatus, it is evacuated and surface-cleaned by surface etching, and Ru / PtMn (20 nm) / Co 9 Fe 1 (20 nm) / Cu (6 nm) / Co 9 Fe 1 (0.8 nm) / NiFe (0.8 nm) / Co 9 Fe 1 (0.8 nm) / Al were sequentially grown. Next, in this state, oxygen is introduced into the chamber to oxidize the aluminum on the surface, and then evacuate again to ultrahigh vacuum, and the remaining Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) was deposited, and an upper electrode was formed.

Next, this wafer was put in a vacuum magnetic field furnace and annealed in a magnetic field at 270 ° C. for 12 hours to introduce an exchange bias into the magnetic pinned layer. At that time, the direction of the exchange bias was made parallel to the longitudinal direction of the element.
Sample B50 was produced by the same method as A10.

Samples C50 and D50 were prepared for comparison.
Sample C50 has Co 9 Fe 1 (12 nm) as magnetic pinned layer C2, Cu (6 nm) as intermediate layer B2, and Co 9 Fe 1 (0.8 nm) / NiFe (magnetic recording layer A) on the lower electrode. 0.8 nm) / Co 9 Fe 1 (0.8 nm), PtMn (15 nm), and an upper electrode have a single pin structure formed in this order.

Sample D50 has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 as the magnetic pinned structure. (4 nm), Cu (6 nm) as the intermediate layer B2, and Co 9 Fe 1 (0.8 nm) / NiFe (0.8 nm) / Co 9 Fe 1 (0.8 nm) as the magnetic recording layer A, It has a single pin structure in which an upper electrode is formed.

  FIG. 43 is a graph showing the relationship between the differential resistance change and the current for samples A50, B50, C50, and D50. Here, the size of the sample is 60 nm × 110 nm. FIG. 43 shows that samples A50 and B50 have a lower critical current Ic for magnetization reversal than samples C50 and D50, and can be written with a low current.

  FIG. 44 is a graph showing the relationship between the average value of the critical current Ic and the cell size. In any sample, the critical current Ic is approximately proportional to the cell size. It can be seen that the samples A50 and B50 can be recorded at a lower current density than the samples C50 and D50.

  As described above, it was confirmed that the structure shown in FIGS. 21 and 25 is suitable for a magnetic cell capable of writing with low power consumption.

In addition, MgO, SiO 2 , Si—O—N, holes are formed in the intermediate layer B2 or the intermediate layer B1 of the samples A50 and B50, and the holes are filled with a magnetic material or conductive metal (Cu, Ag, Au). It has been found that the same tendency as described above can be obtained even when rare SiO 2 or Al 2 O 3 is used.

(Thirteenth embodiment)
Next, as a thirteenth embodiment of the present invention, a sample using an antiferromagnetically coupled three-layer film as a magnetic pinned structure was compared with a sample using a single magnetic layer as a magnetic pinned layer. That is, magnetic cells having the structures shown in FIG. 15 (samples A60 and E60), FIG. 14 (samples B60 and F60), FIG. 22 (samples C60 and G60), and FIG. 45 (samples D60 and H60) were prepared.

Sample A60 (FIG. 15) has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C2, Al 2 O 3 (0.8 nm) as the intermediate layer B2, and a magnetic recording layer Co 9 Fe 1 (2.5 nm) as A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) as the magnetic pinned structure P1, On top of that, PtMn (15 nm) and an upper electrode are formed as an antiferromagnetic layer AF1. That is, sample A60 also has an antiparallel dual pin structure.

Sample B60 (FIG. 14) has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C2, Al 2 O 3 (0.8 nm) as the intermediate layer B2, and a magnetic recording layer Co 9 Fe 1 (2.5 nm) as A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C1, and PtMn (15 nm) as the antiferromagnetic layer AF1 are stacked thereon. The upper electrode is further formed. That is, the sample B60 also has an antiparallel dual pin structure.

Sample C60 (FIG. 22) has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) as the magnetic pinned structure P2. / Co 9 Fe 1 (4 nm), Al 2 O 3 (0.8 nm) as the intermediate layer B 2 , Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B 1 , and magnetic pinned structure P 1 Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) is stacked, and PtMn (15 nm) and an upper electrode are formed thereon. That is, the sample C60 also has an antiparallel dual pin structure.

Sample D60 (FIG. 45) has PtMn (20 nm) on the lower electrode and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) as the magnetic pinned structure P2. / Co 9 Fe 1 (4 nm), Al 2 O 3 (0.8 nm) as the intermediate layer B 2 , Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B 1 , magnetic pinned layer Co 9 Fe 1 (4 nm) is laminated as C1, and PtMn (15 nm) and an upper electrode are formed thereon. That is, the sample D60 also has an antiparallel dual pin structure.

Sample E60 (FIG. 15) has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (4 nm) as magnetic pinned layer C2, Al 2 O 3 (0.8 nm) as intermediate layer B2, and magnetic recording layer Co 9 Fe 1 (2.5 nm) as A, Cu (6 nm) as the intermediate layer B1, and Co 9 Fe 1 (5 nm) / Ru (1 nm) / Co 9 Fe 1 (6 nm) as the magnetic pinned structure P1, It has an antiparallel dual pin structure composed of a structure in which PtMn (15 nm) and an upper electrode are formed thereon.

Sample F60 (FIG. 14) has PtMn (20 nm) on the lower electrode, Co 9 Fe 1 (4 nm) as the magnetic pinned layer C2, Al 2 O 3 (0.8 nm) as the intermediate layer B2, and a magnetic recording layer Co 9 Fe 1 (2.5 nm) as A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (6 nm) as the magnetic pinned layer C1, and PtMn (15 nm) and the upper electrode are formed thereon. It has an antiparallel dual pin structure.

Sample G60 (FIG. 22) has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) as the magnetic pinned structure P2. / Co 9 Fe 1 (3 nm), Al 2 O 3 (0.8 nm) as the intermediate layer B2, Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B1, magnetic fixed structure Co 9 Fe 1 (5 nm) / Ru (1 nm) / Co 9 Fe 1 (6 nm) is laminated as P1, and has an antiparallel dual pin structure composed of PtMn (15 nm) and an upper electrode formed thereon. .

Sample H60 (FIG. 45) has PtMn (20 nm) on the lower electrode, and Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) as the magnetic pinned structure P2. / Co 9 Fe 1 (3 nm), Al 2 O 3 (0.8 nm) as the intermediate layer B 2 , Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B 1 , magnetic pinned layer As C1, Co 9 Fe 1 (6 nm) is laminated, and PtMn (15 nm) and an upper electrode are formed on the Co 9 Fe 1 (6 nm).

The element size is 50 nm × 120 nm for all samples. For samples A60 to H60, the average value of the critical current Ic determined from the current dependency of the differential resistance change was determined. The results are as follows.

Sample Average of critical current Ic (mA)
A60 0.36
B60 0.60
C60 0.29
D60 0.54
E60 0.32
F60 0.55
G60 0.28
H60 0.53

The results of low Ic were obtained for any of the inventive samples. Comparing samples A60 and B60, the magnetic pinned structure P1 in which the magnetization is arranged in antiparallel is provided (FIG. 15), compared to the case where the upper magnetic pinned layer is a single magnetic layer C1 (FIG. 14). The smaller critical current Ic is obtained. Similarly, comparison between sample C60 (FIG. 22) and sample D60 (FIG. 45), comparison between sample E60 (FIG. 15) and sample F60 (FIG. 14), sample G60 (FIG. 22) and sample H60 (FIG. 45). In both cases, the magnetic pinned structure P1 in which the magnetization is arranged in antiparallel is provided (FIG. 14 and FIG. 45) as compared with the case where the upper magnetic pinned layer is a single magnetic layer C1 (FIGS. 14 and 45). 15, FIG. 22) provides a smaller critical current Ic.

That is, it was confirmed that the effect of lowering the critical current Ic was significant by using a laminated film of a magnetic layer and a nonmagnetic layer that were antiparallel coupled as the magnetization fixed structure. The same effect was obtained when the material of the intermediate layer B2 was other than an insulator. The same effect was obtained when the magnetic recording layer A was composed of three magnetic layers.

(Fourteenth embodiment)
Next, as a fourteenth embodiment of the present invention, a cell having a structure described below was manufactured with an element size of 60 nm × 130 nm, and the average critical current Ic was obtained. The laminated structure of the sample of this example viewed from the lower electrode and the measurement result of the critical current Ic are shown below. From this result, it can be seen that according to the present invention, a magnetic cell capable of writing with low power consumption can be provided.

Sample A70: AF2 (PtMn: 20 nm) / C2 (Co 9 Fe 1 : 20 nm) / B2 (MgO: 1 nm) / A (Co 9 Fe 1 : 2.5 nm) / B1 (Cu: 6 nm) / C1 (Co 9 Fe 1 : 5 nm) / AC (Ru: 1 nm) / FM (Co 9 Fe 1 : 5 nm) / AF1 (PtMn: 15 nm)
Ic average: 0.67 mA

Sample A71: AF2 (PtIrMn: 17 nm) / FM (Co 9 Fe 1 : 4 nm) / AC (Ru: 1 nm) / C2 (Co 9 Fe 1 : 4 nm) / B2 (MgO: 1 nm) / A3 (Co 9 Fe 1 : 0.8 nm) / A2 (NiFe: 0.8) / A1 (Co 9 Fe 1 : 0.8 nm) / B1 (Cu: 6 nm) / C1 (Co 9 Fe 1 : 4 nm) / AF1 (PtIrMn: 17 nm )
Ic average: 0.41 mA

Sample A72: AF2 (PtMn: 20 nm) / C2 (Co 9 Fe 1 : 20 nm) / B2 (Si—O—N: 1 nm) / A3 (Co 9 Fe 1 : 0.8 nm) / A2 (NiFe: 0.8 nm) ) / A1 (Co 9 Fe 1 : 0.8 nm) / B1 (Cu: 6 nm) / C1 (Co 9 Fe 1 : 4 nm) / AC (Ru: 1 nm) / FM (Co 9 Fe 1 : 4 nm) / AF2 (PtMn: 15 nm)
Ic average: 0.67 mA

Sample A73: AF2 (PtMn: 15 nm) / C2 (Co 9 Fe 1 : 20 nm) / B2 (SiO 2 with holes: 5 nm) / A (Co 9 Fe 1 : 3 nm) / B1 (Cu: 8 nm) / C1 (Co 9 Fe 1 : 4 nm) / AC (Ru: 1 nm) / FM (Co 9 Fe 1 : 4 nm) / AF1 (PtMn: 15 nm)
Ic average: 0.59 mA

Sample A74: AF2 (IrMn: 19 nm) / C2 (Co 8 Fe 2 : 4 nm) / B2 (MgO: 1 nm) / A3 (Co 8 Fe 2 : 0.8 nm) / A2 (NiFeCo: 0.8 nm) / A1 ( Co 8 Fe 2: 0.8nm) / B1 (Cu: 6nm) / C1 (Co 8 Fe 2: 4nm) / AC (Ru: 1nm) / FM (Co 8 Fe 2: 4nm) / AF1 (IrMn: 19m)
Ic average: 0.82 mA

Sample A75: AF2 (PtMn: 20 nm) / C2 (Co 9 Fe 1 : 20 nm) / B2 (Cu: 6 nm) / A3 (Co 9 Fe 1 : 0.8 nm) / A2 (NiFe: 0.8 nm) / A1 (Co 9 Fe 1 : 0.8 nm) / B 1 (Cu: 0.6 nm) / B 1 (Al 2 O 3 with holes stacked with Cu: 3 nm) / B 1 (Cu: 0.6 nm) / C 1 (Co 9 Fe 1 : 4 nm) / AC (Ru: 1 nm) / FM (Co 9 Fe 1 : 4 nm) / AF1 (PtMn: 15 nm)
Ic average: 0.57 mA

Sample A76: AF2 (PtMn: 10 nm) / FM (Co 9 Fe 1 : 4 nm) / AC (Ru: 1 nm) / C2 (Co 9 Fe 1 : 20 nm) / B2 (MgO: 0.8 nm) / A (Co 9 Fe 1 : 3 nm) / B1 (Cu: 6 nm) / C1 (Co 9 Fe 1 : 5 nm) / AF1 (PtMn: 15 nm)
Ic average: 0.83 mA

Sample A77: AF2 (PtMn: 15 nm) / FM (Co 9 Fe 1 : 4 nm) / AC (Ru: 1 nm) / C2 (Co 9 Fe 1 : 4 nm) / B2 (Al 2 O 3 : 0.7 nm) / A3 (Co 9 Fe 1 : 0.6 nm) / A2 (NiFe: 1 nm) / A1 (Co 9 Fe 1 : 0.6 nm) / B1 (Cu: 8 nm) / C1 (Co 9 Fe 1 : 5 nm) / AF1 (PtMn: 15 nm)
Ic average: 0.78 mA

Sample A78: AF2 (PtIrMn: 15 nm) / C2 (Co 9 Fe 1 : 20 nm) / B2 (Al 2 O 3 with holes: 3 nm) / A (Co 9 Fe 1 : 3.6 nm) / B1 (Cu: 6 nm) ) / C1 (Co 9 Fe 1 : 5 nm) / AC (Ru: 1 nm) / FM (Co 9 Fe 1 : 5 nm) / AF1 (PtIrMn: 15 nm)
Ic average: 0.90 mA

Sample A79: AF2 (PtMn: 20 nm) / FM (Co 9 Fe 1 : 5 nm) / AC (Ru: 1 nm) / C2 (Co 9 Fe 1 : 5 nm) / B2 (Cu: 6 nm) / A3 (Co 9 Fe 1 : 0.6 nm) / A2 (NiFe: 1.2) / A1 (Co 9 Fe 1 : 0.6 nm) / B1 (Si—N—O: 1 nm) / C1 (Co 9 Fe 1 : 5 nm) / AF1 ( (PtMn: 15 nm)
Ic average: 0.78 mA

(15th Example)
Next, as a fifteenth embodiment of the present invention, a magnetic cell having a combination showing a reverse type magnetoresistance effect and a magnetic cell having a combination showing a normal type and a reverse type magnetoresistance effect are respectively prepared and evaluated. did.

  FIG. 46 is a schematic diagram showing a cross-sectional structure of a magnetic cell created in the present embodiment. In this magnetic cell (sample X), the magnetic pinned layer C1, the intermediate layer B1, and the magnetic recording layer A exhibit a reverse type magnetoresistance effect, and the magnetic pinned layer C2, the intermediate layer B2, and the magnetic recording layer A also Reverse type magnetoresistance effect is shown.

FIG. 47 is a schematic diagram showing a cross-sectional structure of a magnetic cell of a comparative example. In this magnetic cell (sample Y), the magnetic pinned layer C1, the intermediate layer B1, and the magnetic recording layer A exhibit a reverse type magnetoresistance effect, and the magnetic pinned layer C2, the intermediate layer B2, and the magnetic recording layer A are normal. Shows the type of magnetoresistive effect. Each layer structure is as follows.

Sample X: Fe 3 O 4 / SrTiO 3 (STO) / La 0.7 Sr 0.3 MnO 3 (LSMO) / SrTiO 3 / CoFe / PtMn

Sample Y: Fe 3 O 4 / SrTiO 3 / La 0.7 Sr 0.3 MnO 3 / SrTiO 3 / La 0.7 Sr 0.3 MnO 3 / CoFe / PtMn

Here, in both Fe 3 O 4 / STO / LSMO and LSMO / STO / CoFe, the resistance increased as the magnetic field was applied. That is, the resistance when the magnetizations of the two magnetic layers are parallel is greater than that when the resistance is antiparallel. That is, it was confirmed in advance that a reverse type magnetoresistance effect was exhibited.

Further, the resistance of LSMO / SrTiO 3 / LSMO / CoFe decreased with the application of the magnetic field. That is, the resistance when the magnetizations of the two magnetic layers were parallel was smaller than that when the resistance was antiparallel. That is, it has been confirmed in advance that the normal type MR is indicated.

By using a single crystal substrate as Fe 3 O 4 constituting the lower pinned magnetic layer C2, it was also used as a lower electrode. STO and LSMO films were grown on a heated substrate using a pulsed laser method. Then, the sample was transferred to the sputtering chamber in a vacuum, a CoFe layer and a PtMn layer were formed, and a Ta layer was formed as an upper electrode. After forming these films, the substrate was introduced into an annealing furnace in a magnetic field, an exchange bias was introduced into the CoFe layer in contact with PtMn, and magnetization was fixed in one direction.

Next, the lower STO layer was shaved to form an element. The completed element was placed on one side of a magnet processed into a picture frame shape together with the Fe 3 O 4 substrate, and the magnetization direction of Fe 3 O 4 was fixed in an antiparallel direction to the upper magnetic pinned layer C1.

  For the samples X and Y produced in this way, current was passed between the lower electrode and the upper electrode at 77K, and when the magnetic resistance was first examined, values of 17% and 50% were obtained, respectively.

  Next, the current dependency of the differential resistance was examined at 77K. As a result, the sample X showed a gentle change in the differential resistance centered at about plus 60 mA and minus 55 mA, but a change corresponding to the change in the magnetoresistance. On the other hand, the sample Y did not show a large change in the current value at the differential resistance in the range of plus or minus 100 mA.

As described above, the magnetic cell (sample X) in which the laminated structure sandwiching the intermediate layers B1 and B2 exhibits a reverse type magnetoresistive effect can be written with low power consumption. On the other hand, if the magnetoresistive effect via the intermediate layer B1 is the reverse type and the magnetoresistive effect via the intermediate layer B2 is the normal type (sample Y), the effect of reducing the write current cannot be obtained. Was confirmed.

(Sixteenth embodiment)
Next, as a sixteenth embodiment of the present invention, a magnetic cell having the structure shown in FIG. 14 was prepared (Sample XX). For comparison, a magnetic cell (sample YY) having two magnetic pinned layers C1 and C2 with magnetizations arranged in parallel as shown in FIG. 48 was prepared.

  First, two types of magnetic cells (sample XX, sample YY) created in the present embodiment will be described.

In Sample XX (FIG. 14), PtMn (15 nm) is formed as an antiferromagnetic layer AF2 on a lower electrode (not shown), and Co 9 Fe 1 (12 nm) is formed as a magnetic pinned layer C2 on the intermediate layer. As B2, Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (6 nm) as the magnetic pinned layer C1, and IrMn (as the antiferromagnetic layer AF1) 15 nm) and an “anti-parallel dual pin structure” having a structure in which an upper electrode (not shown) is formed.

On the other hand, in the sample YY (FIG. 48), PtMn (15 nm) is formed as the antiferromagnetic layer AF2 on the lower electrode (not shown), and Co 9 Fe 1 (12 nm) is formed as the magnetic pinned layer C2 thereon. Cu (4 nm) as the intermediate layer B2, Co 9 Fe 1 (2.5 nm) as the magnetic recording layer A, Cu (6 nm) as the intermediate layer B1, Co 9 Fe 1 (6 nm) as the magnetic pinned layer C1, The antiferromagnetic layer AF1 has a structure in which PtMn (15 nm) and an upper electrode (not shown) are formed.

  By the manufacturing method described below, the two magnetic pinned layers C1 and C2 of the sample XX were pinned antiparallel, while the two magnetic pinned layers C1 and C2 of the sample YY were pinned in parallel.

Sample XX was produced as follows.
First, after the lower electrode is formed on the wafer, the wafer is introduced into an ultra-high vacuum sputtering apparatus, and after the surface is sputter-cleaned, PtMn (15 nm) / Co 9 Fe 1 (12 nm) / Cu (4 nm) / A multilayer film of Co 9 Fe 1 (2.5 nm) / Cu (6 nm) / Co 9 Fe 1 (6 nm) / IrMn (15 nm) was deposited and taken out from the apparatus.

  Next, the wafer is put into a vacuum magnetic field furnace, annealed in a magnetic field at 270 ° C. for 10 hours, an exchange bias in the same direction is applied to the fixed layers C1 and C2, and then the temperature is changed to 240 ° C. to reverse the magnetic field polarity Then, annealing was performed in a magnetic field for 1 hour, and an exchange bias opposite to C2 was applied to the pinned layer C1.

  Next, a resist was applied and electron beam exposure was performed with an EB (electron beam) drawing apparatus, and then a mask pattern corresponding to the element size described above was formed. This pattern was milled to the upper part of the magnetic pinned layer C2 by an ion milling device to form an element.

The element shape was set so that the longitudinal axis direction of the element was parallel to the exchange bias direction of the magnetic pinned layers C1 and C2. Then, SiO 2 was embedded around this element, and the upper electrode was formed to complete the magnetic cell.

On the other hand, the sample YY was produced as follows.
First, after the lower electrode is formed on the wafer, the wafer is introduced into an ultra-high vacuum sputtering apparatus, and after the surface is sputter-cleaned, PtMn (15 nm) / Co 9 Fe 1 (12 nm) / Cu (4 nm) / A multilayer film of Co 9 Fe 1 (2.5 nm) / Cu (6 nm) / Co 9 Fe 1 (6 nm) / PtMn (15 nm) was deposited and taken out from the apparatus.

Next, the wafer was put into a vacuum magnetic field furnace, annealed in a magnetic field at 270 ° C. for 10 hours, and an exchange bias was applied to the fixed layers C1 and C2.
Next, a resist was applied and electron beam exposure was performed with an EB (electron beam) drawing apparatus, and then a mask pattern corresponding to the element size described above was formed. This pattern was milled to the top of the magnetic pinned layer C2 by an ion milling device to form an element.

The element shape was set so that the longitudinal axis direction of the element was parallel to the exchange bias direction of the magnetic pinned layers C1 and C2. Then, SiO 2 was embedded around this element, and the upper electrode was formed to complete the magnetic cell.

For two types of element sizes of 50 nm × 110 nm and 80 nm × 160 nm, a current was passed between the upper electrode and the lower electrode up to plus / minus 10 mA, the current dependency of the differential resistance was measured, and the average critical current Ic The value was determined. The results are as follows.

Sample size Average critical current Ic (mA)
XX 50 nm × 110 nm 0.70
XX 80 nm × 160 nm 1.83
YY 50 nm × 110 nm 9.22
YY 80nm × 160nm without inversion

From the above results, the parallel-arranged dual pin structure produced as a reference sample does not have the effect of reducing the inversion current. However, the “anti-parallel dual pin structure” shown in FIG. It turns out that it is possible.

In addition, as the intermediate layer B2 of the sample XX, SiO 2 or Al in which MgO, SiO 2 , Si—O—N, a hole is formed and a magnetic material or a conductive metal (Cu, Ag, Au) is embedded in the hole. It was confirmed that the same tendency as above was obtained when 2 O 3 was used.

(Seventeenth embodiment)
Next, as a seventeenth embodiment of the present invention, a magnetic memory (Magnetic Random Access Memory: MRAM) incorporating the magnetic cell of the present invention and a MOSFET (Metal-Semicoductor-Oxide Field Effect Transistor) will be described.

  FIG. 49 is a schematic diagram showing a cross-sectional structure of a memory cell of the magnetic memory of this example. This magnetic memory has an equivalent circuit shown in FIG. However, the assignment of bit lines and word lines was reversed from that shown. That is, this memory cell has the magnetic cell 10 and MOSFET (TR) of the present invention. The memory cells are provided in a matrix and are connected to the bit line BL and the word line WL, respectively. A specific memory cell is selected by selecting a bit line BL connected to the memory cell and a word line WL connected to the gate G of the MOSFET (TR).

  49A and 49B are conceptual diagrams for explaining the write operation. That is, the writing to the magnetic cell 10 is performed by flowing a current to the magnetic cell 10 through the bit line BL. A signal is written in the magnetic recording layer A by passing a write current Iw larger than the magnetization reversal current Ic. When the magnetic cell 10 is composed of a combination of a normal type MR and a normal type MR, the magnetization of the magnetic recording layer is written so that the direction of magnetization of the magnetic pinned layer where electrons first flowed is the same. I'm stuck. Therefore, the magnetization direction of the magnetic recording layer A changes according to the polarity of the write current Iw, and “0” is written as shown in FIG. 9A, and “0” is written as shown in FIG. 1 ”can be written. The assignment of “0” and “1” may be reversed.

  49 (c) and 49 (d) are conceptual diagrams for explaining a read operation. Reading is detected by the magnitude of the resistance of the magnetic cell 10. The direction of the sense current Ir may be either direction, but the sense current Ir needs to be smaller than the magnetization reversal current Ic.

  In the structure shown in FIG. 49, assuming that the resistance of the lower intermediate layer B2 is larger than the resistance of the upper intermediate layer B1, the sense current Ir flows in the direction shown in FIG. The resistance is large, and the resistance is small when the sense current Ir is passed in the direction shown in FIG. Reading is possible by detecting the difference in resistance as a voltage. Therefore, for example, the case shown in FIG. 10C can be assigned “0”, and the case shown in FIG. However, the assignment of “0” and “1” may be reversed.

Hereinafter, the magnetic memory of this embodiment will be described in more detail with reference to specific examples.
First, a lower wiring and a lower electrode portion are formed on a wafer on which a MOSFET is formed, and then Ta (5 nm) / Ru (2 nm) / PtMn (15 nm) / Co 9 Fe 1 (15 nm) / Al 2 O 3 (0 .8nm) / Co 9 Fe 1 ( 0.6nm) / NiFe (1.2nm) / Co 9 Fe 1 (0.6nm) / Cu (6nm) / Co 9 Fe 1 (4nm) / Ru (1nm) / Co A multilayer film of 9 Fe 1 (4 nm) / PtMn (15 nm) was grown. Then, the multilayer film was finely processed to form an element.

At that time, as shown in FIG. 50, the ion milling was stopped at the upper part of the Al 2 O 3 layer of the intermediate layer B2. This is because when the Al 2 O 3 layer serving as the intermediate layer B2 is ion-milled, the milled material is redeposited on the side surface (redeposition), and current leakage may occur on the side surface of the Al 2 O 3. It is. On the other hand, current leakage due to redeposition can be prevented unless the Al 2 O 3 layer of the intermediate layer B2 is etched by ion milling as shown in FIG.

  When the laminated structure of the magnetic cell was formed by patterning, a wiring was formed on the upper part to produce a 2 × 2 matrix-shaped magnetic memory.

In the obtained magnetic memory, a memory cell was selected by selecting a word line WL and a bit line BL.
Write current (1) plus or minus 0.15 mA, pulse current of 20 milliseconds, (2) plus or minus 0.5 mA, pulse current of 10 milliseconds, (3) plus or minus 2 mA, 0.8 nanoseconds 3 Tested as street. Reading was performed by flowing a sense current of 0.1 mA and reading the voltage. As a result, in the case of the above condition (1), it was clarified that the resistance change after writing was not seen and recorded.

  Under the condition (2), the resistance changed from the low resistance state to the high resistance state when a write current Iw of minus 0.5 mA was first supplied. However, even after writing with a current pulse with the polarity reversed, the resistance remained in a high resistance state. From this, it can be seen that the signal could be written in only one direction.

  Under the condition (3), the resistance changed according to the polarity of the write current Iw, and it was possible to write both the “0” signal and the “1” signal.

  In addition, by applying a pulse current of 0.3 mA for 10 nanoseconds to a word line (not shown), it was possible to write even under the condition (2) where the writing was insufficient earlier. This is because the current magnetic field generated from the added word line promoted magnetization reversal by spin-polarized electrons.

  From the above, it has been shown that the magnetic memory of the present invention is suitable for a magnetic memory capable of recording at a low current.

There are other methods for selecting a memory cell in the magnetic memory of the present invention besides MOSFET.
FIG. 51 is a schematic diagram showing a magnetic memory using a diode. That is, the magnetic cell 10 of the present invention and the diode D are connected in series near the intersection of the bit line BL and the word line WL wired in a matrix form.

In the case of this magnetic memory, a specific memory cell can be accessed by designating the word line WL and the bit line BL. In this case, the diode D has a role of blocking current components flowing through other memory cells connected to the selected word line WL and bit line BL.

(Eighteenth embodiment)
Next, a probe access type magnetic memory shown in FIG. 26 will be described as an eighteenth embodiment of the present invention.

In this example, the recording / reproducing integrated magnetic element shown in FIG. 27 was formed on the substrate.
First, after forming the lower wiring on the wafer, the lower electrode LE commonly connected to the plurality of magnetic cells was formed. And on this wafer, Ta (5 nm) / Ru (2 nm) / PtMn (15 nm) / Co 9 Fe 1 (15 nm) / Al 2 O 3 (0.8 nm) / Co 9 Fe 1 (2 nm) / Cu ( 6 nm) / Co 9 Fe 1 (4 nm) / Ru (1 nm) / Co 9 Fe 1 (4 nm) / PtMn (15 nm) / Pt (2 nm) was grown.

A cell mask was formed by applying a two-phase separation polymer to the multilayer film and heat-treating it. Next, a patterned medium can be formed by performing ion milling. The ion milling is performed under the magnetic recording layer Co 9 Fe 1 (2 nm), and the intermediate layer B2 (Al 2 O 3 (0.8 nm)) and the magnetic pinned layer C2 (Co 9 Fe 1 (15 nm)) have a plurality of layers. A structure shared by magnetic cells was formed.

  In this structure, since the intermediate layer B2 is not patterned, it is possible to prevent the formation of an unexpected current path due to redeposition on the side surface. Further, uniformity of cell resistance can be obtained. Thereby, a plurality of magnetic cells having a diameter of about 28 nm can be formed. Next, an insulator 100 was embedded between the magnetic cells to complete the structure shown in FIG.

A cell can be selected by scanning the plurality of magnetic cells 10 with the probe 200 and electrically contacting each cell.
First, a current of plus 0.2 mA (here, the direction in which electrons flow from the upper electrode to the lower electrode is defined as plus) is applied to the cell 1 to write a signal “1”, and the cell 2 is minus 0. A signal of “0” was written by passing a current of 2 mA. Further, a signal of “1” was written by passing a plus 0.2 mA current to the cell 3, and a signal “0” was written by feeding a minus 0.2 mA current to the cell 4.

  Next, reading was performed. That is, a sense current of plus 0.03 mA was passed, and the resistance of each cell was examined. As a result, the detected resistance was binary, and from cell 1 to cell 4 were high resistance, low resistance, high resistance, and low resistance, respectively. That is, it was confirmed that a “1” or “0” signal was written in each cell.

When the write current was plus or minus 0.05 mA, stable signal writing could not be performed.
As described above, it was confirmed that the magnetic memory of this example was suitable for a magnetic memory capable of recording with a low current.

  The embodiments of the present invention have been described above with reference to specific examples. However, the present invention is not limited to these specific examples. For example, regarding the specific dimensional relationship and materials of each element constituting the magnetic cell, and other shapes and materials such as electrodes, passivation, and insulation structures, those skilled in the art can appropriately select the present invention by appropriately selecting from a known range. As long as the same effect can be obtained, it is included in the scope of the present invention.

  In addition, components such as an antiferromagnetic layer, a magnetic pinned layer, an intermediate layer, a magnetic recording layer, and an insulating layer in a magnetic cell may be formed as a single layer, or a structure in which two or more layers are laminated. Good.

  In addition, all magnetic cells and magnetic memories that can be implemented by those skilled in the art based on the magnetic cells and magnetic memories described above as the embodiments of the present invention as long as they include the gist of the present invention. It belongs to the scope of the present invention.

FIG. 3 is a schematic view illustrating the basic cross-sectional structure of the magnetic cell according to the first embodiment of the invention. It is a schematic diagram showing the cross-sectional structure of a magnetic cell in which magnetization is controlled in a direction perpendicular to the film surface. FIG. 2 is a schematic cross-sectional view for explaining a “write” mechanism in the magnetic cell shown in FIG. 1. FIG. 5 is a schematic cross-sectional view for explaining a “write” mechanism when a magnetic cell exhibits a reverse type magnetoresistive effect. FIG. 3 is a schematic cross-sectional view for explaining a “write” mechanism in the magnetic cell shown in FIG. 2. It is a conceptual diagram for demonstrating the reading method of the magnetic cell of embodiment of this invention. It is a conceptual diagram for demonstrating the change of the magnetic resistance by the relative direction of magnetization. It is a schematic cross section showing the 1st specific example of an asymmetric structure. (A) is a schematic cross section showing a second specific example of an asymmetric structure, and (b) is a schematic cross section showing a third specific example of the asymmetric structure. It is a schematic cross section showing the 4th example of an asymmetric structure. It is a schematic cross section showing the 5th example of an asymmetric structure. It is a schematic cross section showing magnetostatic coupling of fixed layers C1 and C2. It is a schematic cross section showing the magnetic cell which provided the antiferromagnetic layer. 3 is a schematic cross-sectional view showing a magnetic cell in which magnetizations of fixed layers C1 and C2 are fixed by antiferromagnetic layers, respectively. FIG. It is a schematic diagram showing the magnetic cell which fixed the magnetization of the pinned layers C1 and C2 by the antiferromagnetic layer, respectively. FIG. 5 is a schematic cross-sectional view showing another specific example of a magnetic cell in which the magnetizations of the pinned layers C1 and C2 are pinned by an antiferromagnetic layer. It is a graph showing the film thickness dependence of the interlayer exchange interaction through a nonmagnetic layer. It is a schematic cross section showing a magnetic cell provided with two magnetic recording layers. 3 is a schematic cross-sectional view showing a specific example in which a magnetic pinned layer and a magnetic recording layer A are respectively laminated structures. FIG. 3 is a schematic cross-sectional view showing a specific example in which a magnetic pinned layer and a magnetic recording layer A are respectively laminated structures. FIG. 3 is a schematic cross-sectional view showing a specific example in which a magnetic pinned layer and a magnetic recording layer A are respectively laminated structures. FIG. It is a schematic cross section showing the specific example provided with two magnetic fixation structures. FIG. 6 is a schematic cross-sectional view showing a specific example in which a magnetic recording layer has a laminated structure as well as two magnetic fixing structures. FIG. 6 is a schematic cross-sectional view showing a specific example in which a magnetic recording layer has a laminated structure as well as two magnetic fixing structures. FIG. 6 is a schematic cross-sectional view showing a specific example in which a magnetic recording layer has a laminated structure as well as two magnetic fixing structures. It is a schematic diagram showing the magnetic memory using the magnetic cell of this invention. It is a schematic diagram showing the structure where each cell 10 shares the one part layer. It is a schematic cross section showing the 2nd example of the magnetic memory using the magnetic cell of this invention. (A) is a schematic diagram showing the principal part sectional structure of the magnetic cell of a present Example, The figure (b) is a schematic diagram showing the principal part sectional structure of the magnetic cell of a comparative example. It is a schematic diagram showing the probing in 5th Example. It is a conceptual diagram showing the magnetic memory in 6th Example of this invention. It is a graph showing the differential resistance of sample A10. It is a graph showing the differential resistance of sample B10. FIG. 34 is a graph showing a differential resistance change obtained by removing the background curve component in FIGS. 32 and 33 and further normalizing with a differential resistance in a low resistance state. It is a graph showing the relationship between the average value of magnetization reversal critical current Ic, and cell size. It is a schematic diagram showing the cross-sectional structure of sample C20. It is a graph showing the current dependence of differential resistance change about sample A20, B20, D20, and E20 of size 60nmx110nm. It is a graph showing the relationship between the average value of the critical current Ic and the cell size. It is a graph showing the relationship between differential resistance change and current for samples A30, B30, D30, and E30. It is a graph showing the relationship between the average value of critical current Ic and cell size. It is a graph showing the relationship between differential resistance change and current for samples A40, B40, D40, and E40. It is a graph showing the relationship between the average value of critical current Ic and cell size. It is a graph showing the relationship between differential resistance change and current for samples A50, B50, C50, and D50. It is a graph showing the relationship between the average value of critical current Ic and cell size. It is a schematic diagram showing the structure of the sample D60 and sample H60 in 13th Example of this invention. It is a schematic diagram showing the cross-sectional structure of the magnetic cell created in this implementation. It is a schematic diagram showing the cross-sectional structure of the magnetic cell of a comparative example. It is a schematic diagram showing the cross-sectional structure of a magnetic cell having two magnetic pinned layers C1 and C2 whose magnetizations are arranged in parallel. It is a schematic diagram showing the cross-sectional structure of the memory cell of the magnetic memory of the Example of this invention. It is a schematic view illustrating the structure stopping the ion milling in the Al 2 O 3 layer upper portion of the intermediate layer B2. It is a schematic diagram showing the magnetic memory using a diode.

Explanation of symbols

10 Magnetic cell 100 Insulator 110 Substrate (lower electrode)
120 Wiring 200 Probe 210 Drive mechanism 220 Power supply 230 Detection circuit A, A1, A2 Magnetic recording layer AC Nonmagnetic layer AF, AF1, AF2 Antiferromagnetic layer B, B1-B4 Intermediate layer BL Bit lines C, C1-C3 Magnetic fixing Layer EL1, EL2 electrode FC nonmagnetic layer FM, FM1 magnetic layer I current IE intermediate material layer IL insulating layer Ir reproduction current Is magnetization reversal current Iw current M, M1, M2 magnetization MY magnetic yoke PH magnetic pinned layer hole TR transistor WL word line

Claims (18)

  1. A first ferromagnetic layer whose magnetization is fixed in a first direction perpendicular to the film surface;
    A second ferromagnetic layer which is fixed to a second direction opposite to the magnetization of the first direction,
    A third ferromagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a variable magnetization direction;
    A first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer;
    A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer;
    With
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons are caused to act on the third ferromagnetic layer so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. A magnetic cell characterized in that the direction can be determined according to the direction.
  2. The magnetic cell according to claim 1, wherein an easy axis of magnetization of the third ferromagnetic layer is parallel to the first direction.
  3. The electrical resistance between the first ferromagnetic layer and the third ferromagnetic layer is a first value when the direction of the magnetization of the third ferromagnetic layer is the same as the first direction. And when the direction of the magnetization of the third ferromagnetic layer is the same as the second direction, the second value is larger than the first value.
    The electrical resistance between the second ferromagnetic layer and the third ferromagnetic layer is a third value when the magnetization direction of the third ferromagnetic layer is the same as the second direction. The direction of the magnetization of the third ferromagnetic layer becomes a fourth value larger than the third value in the same state as the first direction. A magnetic cell according to 1.
  4. When an electron current is passed from the first ferromagnetic layer to the second ferromagnetic layer via the third ferromagnetic layer, the magnetization direction of the third ferromagnetic layer is The first direction,
    When an electron current flows from the second ferromagnetic layer to the first ferromagnetic layer via the third ferromagnetic layer, the magnetization direction of the third ferromagnetic layer is The magnetic cell according to claim 1, wherein the magnetic cell has a second direction.
  5. A first ferromagnetic layer whose magnetization is fixed in a first direction;
    A second ferromagnetic layer which is fixed to a second direction opposite to the magnetization of the first direction,
    A third ferromagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a variable magnetization direction;
    A first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer;
    A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer;
    With
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons act on the third ferromagnetic layer, so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. It is possible to determine the direction according to the direction,
    The electrical resistance between the first ferromagnetic layer and the third ferromagnetic layer is a first value when the direction of the magnetization of the third ferromagnetic layer is the same as the first direction. And the magnetization direction of the third ferromagnetic layer becomes a second value smaller than the first value in the same state as the second direction,
    The electrical resistance between the second ferromagnetic layer and the third ferromagnetic layer is a third value when the magnetization direction of the third ferromagnetic layer is the same as the second direction. In the magnetic cell, the direction of the magnetization of the third ferromagnetic layer becomes a fourth value smaller than the third value in the same state as the first direction.
  6.   6. The magnetic cell according to claim 1, wherein an electric resistance of the first intermediate layer and an electric resistance of the second intermediate layer are different from each other.
  7. A first ferromagnetic layer whose magnetization is fixed in a first direction;
    A second ferromagnetic layer which is fixed to a second direction opposite to the magnetization of the first direction,
    A third ferromagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a variable magnetization direction;
    A first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer;
    A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer;
    With
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons act on the third ferromagnetic layer, so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. It is possible to determine the direction according to the direction,
    Either one of the first and second intermediate layers is made of an insulator having a pinhole, and the pinhole is filled with a material of the ferromagnetic layer adjacent to both sides of the insulator. Characteristic magnetic cell.
  8.   8. The magnetization direction of at least one of the first and second ferromagnetic layers is fixed by an antiferromagnetic layer provided adjacent to the first and second ferromagnetic layers. A magnetic cell according to 1.
  9. A first ferromagnetic layer whose magnetization is fixed in a first direction;
    A second ferromagnetic layer which is fixed to a second direction opposite to the magnetization of the first direction,
    A third ferromagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a variable magnetization direction;
    A first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer;
    A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer;
    With
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons act on the third ferromagnetic layer, so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. It is possible to determine the direction according to the direction,
    A nonmagnetic layer, a fourth ferromagnetic layer, and an antiferromagnetic layer are stacked in this order adjacent to at least one of the first and second ferromagnetic layers,
    The magnetic cell according to claim 1, wherein the magnetization directions of the ferromagnetic layers adjacent to both sides of the nonmagnetic layer are fixed in the same direction.
  10. A nonmagnetic layer, a fourth ferromagnetic layer, and an antiferromagnetic layer are stacked in this order adjacent to at least one of the first and second ferromagnetic layers,
    The magnetic cell according to claim 1, wherein magnetization directions of the ferromagnetic layers adjacent to both sides of the nonmagnetic layer are fixed in opposite directions.
  11. A first magnetization pinned portion including a first ferromagnetic layer whose magnetization is fixed in a first direction perpendicular to the film surface;
    A second magnetization pinned portion including a second ferromagnetic layer whose magnetization is fixed in a second direction opposite to the first direction;
    A third ferromagnetic layer provided between the first magnetization pinned portion and the second magnetization pinned portion and having a variable magnetization direction;
    A first intermediate layer provided between the first magnetization pinned portion and the third ferromagnetic layer;
    A second intermediate layer provided between the second magnetization pinned portion and the third ferromagnetic layer;
    With
    The easy axis of magnetization of the third ferromagnetic layer is parallel to the first direction;
    At least one of the first and second magnetization pinned portions is a stacked body in which ferromagnetic layers and nonmagnetic layers are alternately stacked and the ferromagnetic layers are antiferromagnetically coupled via the nonmagnetic layers. Have
    The first ferromagnetic layer is adjacent to the first intermediate layer;
    The second ferromagnetic layer is adjacent to the second intermediate layer;
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    Magnetization of the third ferromagnetic layer by causing spin-polarized electrons to act on the third ferromagnetic layer by passing a current between the first magnetization fixed portion and the second magnetization fixed portion. The magnetic cell is characterized in that the direction can be determined according to the direction of the current.
  12.   One of the first and second magnetization pinned portions has an even number of the ferromagnetic layers, and one of the first and second magnetization pinned portions has the other number of the ferromagnetic layers. 12. The magnetic cell according to claim 11, wherein the magnetic cell is an odd number.
  13. A substrate on which the first and second magnetization pinned portions, the third ferromagnetic layer, and the first and second intermediate layers are stacked;
    The magnetic cell according to claim 12, wherein the number of the ferromagnetic layers included in the first and second magnetization fixed portions provided on the side far from the substrate is an even number.
  14. A first ferromagnetic layer whose magnetization is fixed in a first direction;
    A second ferromagnetic layer which is fixed to a second direction opposite to the magnetization of the first direction,
    A third ferromagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a variable magnetization direction;
    A first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer;
    A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer;
    With
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons act on the third ferromagnetic layer, so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. It is possible to determine the direction according to the direction,
    The magnetic cell according to claim 3, wherein the third ferromagnetic layer is a laminated body in which a plurality of layers made of a ferromagnetic material are laminated.
  15.   Either one of the first and second intermediate layers is made of a conductor, and the other is made of an insulator. cell.
  16.   A magnetic memory comprising a memory cell in which a plurality of magnetic cells according to claim 1 are provided in a matrix with an insulator interposed therebetween.
  17. A memory cell having a plurality of magnetic cells arranged in a matrix with an insulator interposed therebetween,
    Each of the plurality of magnetic cells is
    A first ferromagnetic layer whose magnetization is fixed in a first direction perpendicular to the film surface;
    A second ferromagnetic layer which is fixed to a second direction opposite to the magnetization of the first direction,
    A third ferromagnetic layer provided between the first ferromagnetic layer and the second ferromagnetic layer and having a variable magnetization direction;
    A first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer;
    A second intermediate layer provided between the second ferromagnetic layer and the third ferromagnetic layer;
    Have
    The first intermediate layer provided between the first ferromagnetic layer and the third ferromagnetic layer, and between the second ferromagnetic layer and the third ferromagnetic layer Each provided with the second intermediate layer constitutes a magnetoresistive effect element,
    By causing a current to flow between the first and second ferromagnetic layers, spin-polarized electrons act on the third ferromagnetic layer, so that the magnetization direction of the third ferromagnetic layer changes the direction of the current. It is possible to determine the direction according to the direction,
    A magnetic memory characterized in that each of the magnetic cells on the memory cell can be accessed by a probe.
  18. A word line and a bit line are connected to each of the magnetic cells on the memory cell,
    17. The magnetic memory according to claim 16, wherein information can be recorded or read from a specific magnetic cell by selecting the word line and the bit line.
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