JP2004006774A - Solid magnetic element and solid magnetic element array - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new solid magnetic element that can be selected even when the element is arrayed, and to provide a solid magnetic element array formed by arraying the element. <P>SOLUTION: The solid magnetic element has a reference magnetic section A, a recording section W having a spin transfer intermediate section B composed of a nonmagnetic material and a recording magnetic section C which is magnetically softer than the magnetic section A, and a reproducing section R having the recording magnetic section C, an MR intermediate section D, and a reference magnetic section E. Writing is performed in the recording section W by means of a directly current-driven magnetization inverting mechanism and readout is performed in the reproducing section R by utilizing a magnetoresistive effect. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a solid-state magnetic element and a solid-state magnetic element array, and more particularly, to a solid-state magnetic element and a solid-state magnetic element array capable of performing current direct drive recording and reproduction by a magnetoresistance effect.
[0002]
[Prior art]
Since it was found that a giant magnetoresistance effect was exhibited when an electric current was flowed in a plane in a laminated structure composed of a ferromagnetic layer / a nonmagnetic layer / a ferromagnetic layer, a large magnetoresistance change occurred. As a system having a ratio, a CPP (Current Perpendicular to Plane) type magnetoresistive element in which a current flows in a direction perpendicular to the laminated structure and a ferromagnetic tunnel magnetoresistive element in which a nonmagnetic layer is made of an insulator have been developed. .
[0003]
Further, as a system exhibiting a greater magnetoresistance effect, a "magnetic microcontact" in which two needle-like nickels (Ni) are put together (N. Garcia, M. Munoz, and Y.-W. Zhao, Physical Review Letters). 82, p. 2923 (1999)), or a magnetic microcontact in which two magnetites are brought into contact (JJ Versluijs, MA Bari and JMD Coey, Physical Review Letters, vol. 87). , P26601 -1 (2001)).
[0004]
These magnetoresistive elements are being used not only as magnetic sensors and reproducing elements in magnetic recording and reproducing systems, but also as non-volatile solid-state magnetic memories.
[0005]
When the magnetoresistive element is used as a solid-state magnetic element, writing depends on a leakage magnetic field, which is a current magnetic field applied from a wiring provided near the magnetoresistive element. However, in this case, there is a drawback that the current required to cause the magnetization reversal for recording is as large as several milliamps or more.
[0006]
On the other hand, “current direct drive type magnetization reversal” in which magnetization reversal for recording is performed by flowing a current directly to the recording magnetic part has been found (JC Slonczewski, J. Magn. Magn. Mater. 159, L1 (1996), EB Myers, et al., Science 285, 867 (1999), JA Katine, et al., Phys. Rev. Lett. 14, 3149 (2000). J. Albert, et al., Appl. Phys. Lett. 77, 3809 (2000) .J.-E. Weglowe, et al., Europhys. Lett., 45, 626 (1999) .J.Z. , J. Magn. Magn. Mater. 202, 157 (1 99).).
[0007]
This phenomenon is caused by the fact that the angular momentum of spin-polarized electrons generated when a spin-polarized current flows when passing through the reference magnetic section or the surrounding magnetic layer is transferred to the angular momentum of the recording magnetic section. It is a reversal. According to this phenomenon, it is expected that the current required for the magnetization reversal at the time of recording is reduced because it can be made to act more directly on the recording layer.
[0008]
The direct current type magnetic recording element and the magnetoresistive element described above have been different from each other. However, when they are combined, recording and reproduction can be handled by one element, which is expected to contribute to miniaturization of the element.
[0009]
However, the recording section including the recording magnetic section has an extremely low electric resistance. For this reason, it is difficult to operate in combination with a magnetoresistive unit having a higher resistance than the recording unit. Further, since the electric resistance of the recording unit is small, it is difficult to select an element particularly when the elements are arrayed.
[0010]
The present invention has been made based on the recognition of such a problem, and an object of the present invention is to provide a novel solid-state magnetic element in which elements can be selected even in an array, and a solid-state magnetic element array in which the elements are arrayed. is there.
[0011]
[Problems to be solved by the invention]
A magnetic element using current direct drive type magnetization reversal is expected to reduce current, but has a problem that it is difficult to select elements when arrayed due to low electric resistance.
[0012]
A magnetic element using current direct drive type magnetization reversal is expected to reduce current, but has a small electric resistance. For this reason, it is difficult to combine with a magnetoresistive effect part whose resistance is larger than that of the recording part. In addition, there is a problem that it is difficult to select elements when arraying.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, a first solid-state magnetic element of the present invention comprises:
A first reference magnetic unit including a first ferromagnetic material having a magnetization direction fixed in a first direction;
A second reference magnetic unit including a second ferromagnetic material whose magnetization direction is fixed in a second direction;
A recording magnetic unit provided between the first and second reference magnetic units and including a third ferromagnetic material;
A spin transfer intermediate part provided between the first reference magnetic part and the recording magnetic part,
An MR intermediate part provided between the second reference magnetic part and the recording magnetic part;
With
By passing a write current between the first reference magnetic section and the recording magnetic section, the magnetization of the third ferromagnetic material is directed substantially parallel or substantially anti-parallel to the first direction,
By flowing a sense current between the second reference magnetic section and the recording magnetic section, it is possible to detect the relative relationship between the second direction and the direction of magnetization of the third ferromagnetic material. It is characterized by having done.
[0014]
Further, the second solid-state magnetic element of the present invention comprises:
A first reference magnetic unit including a first ferromagnetic material having a magnetization direction fixed in a first direction;
A second reference magnetic unit including a second ferromagnetic material whose magnetization direction is fixed in a second direction;
An MR intermediate portion provided between the first and second reference magnetic portions;
A first recording magnetic part provided between the first reference magnetic part and the MR intermediate part and having a third ferromagnetic material;
A second recording magnetic unit provided between the second reference magnetic unit and the MR intermediate unit and having a fourth ferromagnetic material;
A first spin transfer intermediate unit provided between the first reference magnetic unit and the first recording magnetic unit;
A second spin transfer intermediate section provided between the second reference magnetic section and the second recording magnetic section;
With
By passing a write current between the first reference magnetic part and the first recording magnetic part, the magnetization of the third ferromagnetic material is oriented substantially parallel or substantially anti-parallel to the first direction. Towards
By passing a write current between the second reference magnetic section and the second recording magnetic section, the magnetization of the fourth ferromagnetic material is oriented substantially parallel or substantially anti-parallel to the second direction. Towards
By flowing a sense current between the first recording magnetic part and the second recording magnetic part, the relative relationship between the magnetization directions of the third ferromagnetic material and the fourth ferromagnetic material is obtained. Is detectable.
[0015]
On the other hand, the solid-state magnetic element array of the present invention includes:
A plurality of solid-state magnetic elements according to claim 1,
Selecting means for selecting any one of the plurality of solid-state magnetic elements and flowing the write current or the sense current;
It is characterized by having.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0017]
FIG. 1 is a schematic view illustrating the basic cross-sectional structure of the solid-state magnetic element according to the first embodiment of the present invention. This magnetic element has a recording unit W for directly writing by a current and a reproducing unit R for reading by a magnetoresistance effect. The recording unit W and the reproducing unit R share the recording layer C.
[0018]
In other words, the recording unit W includes a reference magnetic unit A made of a hard magnetic material, a spin transfer intermediate unit B made of a non-magnetic material, and a recording magnetic unit C magnetically softer than the reference magnetic unit A. Having a structure. On the other hand, the reproducing section R has a recording magnetic section C, an MR intermediate section D, and a reference magnetic section E made of a magnetic material harder than the recording magnetic section C.
[0019]
Electrodes E1, E2, and E3 are connected to the reference magnetic section A, the recording magnetic section C, and the reference magnetic section E, respectively. The MR intermediate part D is made of a conductive metal and / or an insulator.
[0020]
The direction in which the electrodes are taken out may be horizontal or vertical in FIG. 1, but these are for convenience and may be either oblique or oblique. This is common to all subsequent figures.
[0021]
In the solid-state magnetic element shown in FIG. 1, “writing” can be performed in the recording unit W by a current direct drive type magnetization reversal mechanism. That is, the magnetization of the recording magnetic part C is reversed by the spin polarization current.
[0022]
FIG. 2 is a schematic diagram illustrating the operation of the recording unit W in the solid-state magnetic element of the present invention.
[0023]
That is, as shown in FIG. 1A, when an electron current is applied from the reference magnetic section A to the recording magnetic section C, the recording magnetic section C has the same direction as the magnetization M1 of the reference magnetic section A. Can be written. That is, when an electron current flows in this direction, the spin of the electron is first polarized in the reference magnetic section A in accordance with the direction of the magnetization M1. Then, the spin-polarized electrons flow into the recording magnetic part C, and reverse the magnetization M2 in the same direction as the magnetization M1 of the reference magnetic part A.
[0024]
On the other hand, as shown in FIG. 2B, when an electron current flows from the recording magnetic part C to the reference magnetic part A, writing can be performed in the opposite direction. In other words, the spin electrons corresponding to the magnetization M1 of the reference magnetic part A can easily pass through the reference magnetic part A, whereas the spin electrons in the opposite direction to the magnetization M1 generate the spin transfer intermediate part B and the reference magnetic part A. Is reflected with high probability at the interface with. Then, the spin-polarized electrons reflected in this way return to the recording magnetic part C, thereby reversing the magnetization M2 of the recording magnetic part C in a direction opposite to that of the reference magnetic part M1.
[0025]
As described above, in the present invention, a predetermined magnetization can be written in the recording magnetic portion C by a current direct drive type magnetization reversal mechanism using a spin-polarized current. For this reason, it is possible to reduce the current required for the magnetization reversal at the time of recording as compared with the conventional recording element in which the recording layer is reversed by the leakage current magnetic field.
[0026]
On the other hand, “reading” in the solid-state magnetic element of the present embodiment can be performed in the reproducing section R by the magnetoresistance effect.
[0027]
FIG. 3 is a schematic diagram illustrating the operation of the reproducing unit R in the solid-state magnetic element of the present embodiment.
[0028]
That is, when the magnetization M2 of the recording magnetic part C and the magnetization M3 of the reference magnetic part E are parallel as shown in FIG. 7A, the direction indicated by the arrow in FIG. Good), the resistance obtained by passing a sense current is small.
[0029]
On the other hand, as shown in FIG. 3B, when the magnetization M2 of the recording magnetic part C and the magnetization M3 of the reference magnetic part E are antiparallel, the resistance increases. Therefore, binary information can be reproduced by assigning a “0” level and a “1” level according to these resistance outputs.
[0030]
In the present invention, the magnetization of the recording magnetic section C can be reproduced with high sensitivity by the magnetoresistance effect in the reproducing section R. Further, as will be described in detail later, by appropriately devising the material and structure of the MR intermediate portion D, the electrical resistance of the reproducing portion through which the sense current flows can be increased to an optimum level. As a result, the element selection becomes easy particularly when the elements are arrayed, and a memory element or a logic circuit in which the solid-state magnetic elements are integrated can be realized.
[0031]
Next, each element constituting the solid-state magnetic element of the present invention will be described in detail.
[0032]
First, as materials of the reference magnetic parts A and E and the recording magnetic part C, 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", or a CoNbZr alloy, a FeTaC alloy, a CoTaZr alloy, a FeAlSi alloy Alloys, soft magnetic materials such as FeB-based alloys, CoFeB-based alloys, Heusler alloys, magnetic semiconductors, CrO ₂ , Fe ₃ O ₄ , La _1-X Sr _X MnO ₃ Any of the half metal magnetic oxides (or half metal magnetic nitrides) can be used.
[0033]
Here, the “magnetic semiconductor” includes at least one of iron (Fe), cobalt (Co), nickel (Ni), chromium (Cr), and manganese (Mn), and a compound semiconductor or an oxide semiconductor. For example, (Ga, Cr) N, (Ga, Mn) N, MnAs, CrAs, (Ga, Cr) As, ZnO: Fe, (Mg, Fe) O And the like.
[0034]
In the present invention, as the material of the magnetic layers A, C, and E, a material having magnetic properties according to the intended use may be appropriately selected and used.
[0035]
Further, as a material used for these magnetic layers, a continuous magnetic material may be used, or a composite structure in which fine particles made of a magnetic material are deposited or formed in a non-magnetic matrix may be used.
[0036]
Particularly, as the recording magnetic portion C, a two-layer structure of [(Co or CoFe alloy) / (NiFe or NiFeCo permalloy or Ni)], or [(Co or CoFe alloy) / (NiFe or NiFeCo)] Permalloy alloy or Ni) / (Co or CoFe alloy)] may be used. In the case of a magnetic layer having such a multilayer structure, the outer Co or CoFe alloy preferably has a thickness of 0.2 nm to 3 nm. By employing such a multilayer structure, the current required for recording can be reduced.
[0037]
Further, as the recording magnetic part C, [(magnetic layer of Permalloy or CoFe) / (nonmagnetic layer of Cu or Ru (thickness of 0.2 nm or more and 3 nm or less)) / (permalloy or CoFe or the like) Magnetic layer)], in particular, a multilayer film anti-ferromagnetically interlayer-exchange-coupled can be used as a recording magnetic unit, and is effective for reducing a switching current and a switching magnetic field.
[0038]
On the other hand, in order to fix the magnetization M1 of the reference magnetic portion A or the magnetization M3 of the reference magnetic portion E, an anti-ferromagnetic layer (not shown) may be provided outside each of the reference magnetic portions A and E to apply an exchange bias. . Alternatively, when a non-magnetic layer such as ruthenium (Ru) or copper (Cu), a ferromagnetic layer, and an antiferromagnetic layer are laminated and an exchange bias is applied, the magnetization direction can be controlled, and a signal output with a large magnetoresistance effect can be obtained. Useful to get In particular, by using (ferromagnetic layer such as CoFe) / (nonmagnetic layer such as Cu, Ru) / (magnetic layer such as CoFe) / antiferromagnetic layer which is interlayer-exchange-coupled antiferromagnetically, The leakage magnetic field from the magnetic field can be reduced, and writing to the recording magnetic portion can be performed with a small current.
[0039]
As the antiferromagnetic material therefor, it is desirable to use iron manganese (FeMn), platinum manganese (PtMn), palladium manganese (PdMn), palladium platinum manganese (PdPtMn), or the like.
[0040]
As an example in which the storage layer and the reference layer are multilayered, a cross section of a solid-state magnetic element using a multilayer film antiferromagnetically coupled is illustrated in FIG. As illustrated in the figure, a reference magnetic part A, a spin transfer intermediate part B, a recording magnetic part C, an MR intermediate part D, and a reference magnetic part E of the solid-state magnetic element are respectively provided with an antiferromagnetic film AF and a ferromagnetic substance. F and the nonmagnetic film NM can be formed in combination. In FIG. 4, the direction of the magnetization of the ferromagnetic material F is also indicated by an arrow.
[0041]
On the other hand, the spin transfer intermediate portion B has a role of separating a magnetic domain between the reference magnetic portion A and the recording magnetic portion C. Further, the spin transfer intermediate portion B also has a role as a path for spin-polarized electrons. The structure includes (1) a nonmagnetic noble metal element such as Cu, Ag, or Au, or a metal containing at least one element selected from this group, or (2) a reference magnetic portion or (and / or) It is made of the same constituent element of the magnetic material as the recording magnetic part, but contains a crystal alteration such as a crystal defect, or is formed so as to be provided with surface irregularities to trap a domain wall. This crystal defect can be created by electron beam irradiation or ion irradiation. In addition, the surface irregularities can be formed by providing a constriction on a fine wire.
[0042]
It is more desirable to use a low-resistance material such as Cu, Ag, or Au, for example, as the material of the spin transfer intermediate portion B.
[0043]
On the other hand, the material of the MR intermediate part D is selected from the group consisting of aluminum (Al), titanium (Ti), tantalum (Ta), cobalt (Co), nickel (Ni), silicon (Si) and iron (Fe). An insulator made of an oxide, a nitride, or a fluoride containing at least one selected element can be used. Alternatively, as a material of the MR intermediate portion D, copper (Cu), gold (Au), silver (Ag), or an alloy containing at least one of these can also be used.
[0044]
In order to increase the element resistance of the reproducing section, it is advantageous to use an insulating material as the material of the MR intermediate section D.
[0045]
The thickness of the reference magnetic portions A and E is preferably in the range of 0.6 nm to 100 nm, and the thickness of the recording magnetic portion C is preferably in the range of 0.2 nm to 50 nm. Further, the thickness of the spin transfer intermediate portion B is desirably in the range of 0.2 nm to 100 nm. Further, it is desirable that the MR intermediate portion D be in the range of 0.2 nm to 10 nm.
[0046]
On the other hand, it is desirable to form the recording magnetic layer C, the reference magnetic layer E, and the MR intermediate portion D in a thin film shape or a thin line shape in manufacturing an element.
[0047]
On the other hand, the planar shape of the solid-state magnetic element of the present invention is desirably formed, for example, such that the planar shape of the recording magnetic portion C is a rectangle, a rhombus, or a vertically long (horizontally long) hexagon. It is desirable that the aspect ratio be about 1: 1 to 1: 5 so that uniaxial shape magnetic anisotropy is easily generated.
[0048]
Further, it is desirable that the size of the recording magnetic part C be such that one side in the longitudinal direction is in the range of about 5 nm to 1000 nm. In FIG. 1 and the like, the widths of the reference magnetic portions A and E and the recording magnetic portion C are shown as being the same, but the present invention is not limited to this. That is, the layers of the solid-state magnetic element may be formed so as to have different widths as shown in FIG. 5 for connection of wiring or control of the magnetization direction.
[0049]
FIG. 6 is a schematic cross-sectional view illustrating a modification of the solid-state magnetic element of the present embodiment. In this figure, the same elements as those described above with reference to FIGS. 1 to 5 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0050]
In each of these modifications, a “point contact”, that is, a magnetic microcontact P having a contact area of 100 nm 2 or less is provided in the MR intermediate portion D. The magnetic minute contact P is made of the material of the reference magnetic portion E or the recording magnetic portion C, and the periphery of the MR intermediate portion D is covered with an insulator.
[0051]
The magnetic microcontact P may have a cone-shaped cross section as illustrated in FIG. 6A, or may have a pillar-shaped cross section as illustrated in FIG. Good. Furthermore, a plurality of magnetic microcontacts P may be provided as illustrated in FIGS.
[0052]
When the size of such a magnetic minute contact P is reduced, the electric resistance is reduced by applying a magnetic field. The size at which such a decrease in electrical resistance appears depends on the cross-sectional shape of the microcontact P. However, according to the results of the study by the present inventors, when the maximum width of the microcontact P is approximately 20 nm or less, the electrical resistance is reduced. Was found to be remarkable. At this time, a large magnetoresistance effect occurs in which the magnetoresistance change rate becomes 20% or more. However, when the cross-sectional shape of the minute contact P is extremely flat, the electric resistance may be reduced by the application of the magnetic field even if the maximum width exceeds 20 nm. A solid-state magnetic element having such a minute contact P is also included in the scope of the present invention.
[0053]
That is, by providing such a magnetic minute contact point P, it becomes possible to read out the magnetization of the recording magnetic part C with extremely high sensitivity in the reproducing part R.
[0054]
In the case where such a magnetic minute contact P is provided, the material around the minute contact P in the MR intermediate part D is formed of an insulating material, and the thickness of the MR intermediate part D is 0.2 nm to The thickness may be increased to a range of about 1000 nm.
[0055]
The magnetic minute contact P may be made of copper (Cu) in addition to the material of the reference magnetic portion E or the recording magnetic portion C. In this case, the contact portion may be made of copper (Cu) and its surroundings may be made of an oxide such as aluminum (Al). By doing so, the current path can be narrowed, so that the sensitivity can be increased as compared with normal CPP-MR.
[0056]
FIG. 7A is a schematic cross-sectional view illustrating another modification of the solid-state magnetic element of the present embodiment. In this figure, the same elements as those described above with reference to FIGS. 1 to 6 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0057]
In this modified example, the recording magnetic section C and the reference magnetic section E are respectively stacked on the upper and lower sides of the MR intermediate section D. In FIG. 1, a spin transfer intermediate section B provided on the upper side is further provided. The reference magnetic portions A provided by being laminated on each other are adjacent to each other in the in-plane direction. That is, the spin transfer intermediate portion B and the reference magnetic portion A are provided adjacent to the recording magnetic portion C in the in-plane direction without being laminated in the film thickness direction.
[0058]
Even when the layers of the solid-state magnetic element are arranged in such an arrangement relationship, the input operation by the spin-polarized current described above with reference to FIG. 2 and the output operation by the magnetoresistance effect described above with reference to FIG. 3 can be performed similarly. .
[0059]
Here, the MR intermediate portion D may be formed as a single insulating layer. However, as shown in FIG. 6, by providing one or a plurality of magnetic microcontacts P, the operation described above with reference to FIG. The effect can be obtained similarly.
[0060]
FIG. 7B is a schematic view illustrating a use form of the solid-state magnetic element of FIG. 7A. That is, the electrode E1 is connected to the switching element SW, the electrode E2 is connected to the write wiring, and the electrode E3 is connected to the read wiring. Recording can be performed by supplying a write current to a path from the switching section SW to the write wiring while the switching element SW is turned on. In addition, reading can be performed by flowing a sense current in a path from the switching unit SW to the read wiring in a state where the switching element SW is turned on.
[0061]
In FIGS. 1 to 7, the magnetization directions of the reference recording layers in the same element are shown in the same direction, but this is merely an example, and they may be antiparallel to each other or may be inclined by 90 degrees.
[0062]
As described above with reference to FIGS. 1 to 7, the solid-state magnetic element of the present invention can write the magnetization M2 in the recording magnetic portion C with a smaller write current than the spin polarization current in the recording portion W. In addition, in the reproducing section R, the magnetization M2 of the recording magnetic section C can be read with high sensitivity using the magnetoresistance effect. In addition, there is an advantage that the impedance of the reproducing section R, that is, the element resistance can be increased to an optimum range, and arraying or integration is easy.
[0063]
Therefore, next, a structure in which the solid magnetic elements are arrayed will be described.
[0064]
FIG. 8 is a schematic diagram showing an equivalent circuit of a cell constituting the solid-state magnetic element array according to the embodiment of the present invention. That is, the cell of the element array of the present invention includes the solid-state magnetic element 10 described above with reference to FIGS. 1 to 7 and the switching unit 20 for selecting this element and flowing a current. As described above, the solid-state magnetic element 10 has the recording unit W for writing by applying a current, and the reproducing unit R for reading by the magnetoresistance effect by sharing the recording magnetic portion C of the recording unit W.
[0065]
A recording unit W is provided between the reproducing unit R and the switching unit 20, and a write wiring WL2 is connected between the reproducing unit R and the recording unit W. According to this structure, writing can be performed by turning on the switching unit 20 and causing a current to flow between b and c. Also, by turning the switching unit on and turning on the switching unit 20 and allowing a current to flow between a and c. , A-c can be reproduced by detecting the resistance (voltage) between them. That is, b is connected to the write wiring WL2.
[0066]
This connection is devised because the resistance of the recording unit W is smaller than the resistance of the reproducing unit R. That is, if the positional relationship between the recording unit W and the reproducing unit R is opposite to the relationship shown in FIG. 8, a sufficient current for the magnetization reversal cannot be passed through the recording unit W during writing due to the large resistance of the reproducing unit R. In order to avoid this, a recording unit W is provided between the reproducing unit R and the switching unit 20, and a write wiring WL2 is connected between the reproducing unit R and the recording unit W. In this way, it is possible to select cells for writing and reading by one switching unit 20, and the configuration in the case of integration can be greatly simplified.
[0067]
FIG. 9 is a schematic circuit diagram illustrating a part of the solid-state magnetic element array according to the embodiment of the present invention. That is, this element array can be used, for example, as a magnetic memory and has a structure in which the cells illustrated in FIG. 8 are connected in a matrix. Then, in addition to the write wiring WL2 shown in FIG. 8, three wirings, a reproduction wiring WL1 parallel to the write wiring WL2 and a wiring BL1 for cell selection orthogonal thereto, are shared between the cells.
[0068]
According to this structure, an arbitrary cell can be selectively written and reproduced using the word line (WL1, WL2) and the bit line (BL1) corresponding to the address of the designated cell.
[0069]
FIG. 10 is a schematic circuit diagram showing another specific example of the solid-state magnetic element array according to the embodiment of the present invention. This specific example can also be used as a magnetic memory.
[0070]
In the case of this specific example, a switching unit 20A is connected to the reproducing unit R, and a switching unit 20B is connected to the recording unit W. The write wiring WL1 is connected between the reproducing unit R and the recording unit W. The switching unit 20A is turned on by a wiring BL1, and the switching unit 20B is turned on by a wiring BL2.
[0071]
In the case of this array, a reproducing unit R of an arbitrary cell is selected and read out by the switching unit 20A and the wiring WL1, and a recording unit W of an arbitrary cell is selected by the switching unit 20B and the wiring WL1. Can be written. As described above, as the first embodiment of the present invention, the solid-state magnetic elements illustrated in FIGS. 1 to 10 and their application examples have been described.
[0072]
Next, a second embodiment of the present invention will be described.
[0073]
FIG. 11 is a schematic diagram illustrating a cross-sectional structure of a solid-state magnetic element according to the second embodiment of the present invention.
That is, the solid-state magnetic element of the present embodiment has the reproducing section R at the center, and has two recording sections W1 and W2 on both sides thereof so as to share the recording magnetic section.
[0074]
The laminated structure will be described. A structure in which a reference magnetic part A, a spin transfer intermediate part B, a recording magnetic part C, an MR intermediate part D, a recording magnetic part E, a spin transfer intermediate part F, and a reference magnetic part G are laminated in this order. Having. The recording section W1 is composed of the reference magnetic section A, the spin transfer intermediate section B, and the recording magnetic section C, and the reproducing section R is composed of the recording magnetic section C, the MR intermediate section D, and the recording magnetic section E. The recording section W2 is composed of the magnetic section E, the spin transfer intermediate section F, and the reference magnetic section G.
[0075]
The material, thickness, size, and the like of each of these layers can be the same as those described above with respect to the first embodiment.
[0076]
The operation will be described. First, in the writing, a current is caused to flow between the electrodes E1 and E2 to perform the magnetization reversal of the recording magnetic portion C to perform writing to the recording magnetic portion C, and a current is caused to flow between the electrodes E3 and E4. As a result, the magnetization of the recording magnetic part E is inverted, and writing to the recording magnetic part E is performed. These writing mechanisms are based on a current direct drive type magnetization reversal mechanism using a spin-polarized current, as described above with reference to FIG.
[0077]
On the other hand, in the reproduction, the relative angle of the magnetization between the recording magnetic portions C and E is detected as a magnetoresistance by flowing a sense current between the electrodes E2 and E3. The mechanism is similar to that described above with reference to FIG.
[0078]
As described above, the solid-state magnetic element of this embodiment can store information independently in the two recording magnetic units.
[0079]
FIG. 12 is a schematic cross-sectional view illustrating a modification of the solid-state magnetic element of the present embodiment. In this figure, the same elements as those described above with reference to FIG. 11 are denoted by the same reference numerals, and detailed description will be omitted.
[0080]
That is, these modified examples have a point contact, that is, a magnetic minute contact P, like the element illustrated in FIG. As described above, by providing such a small contact point P, a high rate of change in magnetoresistance can be obtained, and the magnetization recorded in the recording magnetic portions C and E can be read with extremely high sensitivity.
[0081]
Although the magnetization directions of the reference recording layers in the same element are shown in FIGS. 11 and 12 in the same direction, this is merely an example, and they may be antiparallel to each other or may be inclined by 90 degrees.
[0082]
FIG. 13A is a schematic cross-sectional view illustrating another modified example of the solid-state magnetic element of the present embodiment. In this figure, the same elements as those described above with reference to FIGS. 1 to 12 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0083]
Also in this modified example, the recording magnetic parts C and E are laminated on the upper and lower sides of the MR intermediate part D, respectively, but the spin transfer intermediate parts B and F and the reference magnetic parts A and G are composed of the recording magnetic parts C and E. Are provided adjacent to each other in the in-plane direction without being laminated in the film thickness direction. The electrode E1 is connected to the reference magnetic part A, the electrode E2 is connected to the recording magnetic part C, the electrode E3 is connected to the recording magnetic part E, and the electrode E4 is connected to the reference magnetic part G.
[0084]
Even when the layers of the solid-state magnetic element are arranged in such an arrangement relationship, the input operation by the spin-polarized current described above with reference to FIG. 2 and the output operation by the magnetoresistance effect described above with reference to FIG. 3 can be performed similarly. .
[0085]
Here, the MR intermediate portion D may be formed as a single insulating layer. However, as shown in FIG. 6 and FIG. The operation and effect described above with reference to FIG. 12 can be similarly obtained.
[0086]
FIG. 13B is a schematic view illustrating a use form of the solid-state magnetic element of FIG. That is, the electrodes E1 and E4 are connected to the switching elements SW1 and SW2, respectively, and the electrodes E2 and E3 are connected to the write wirings 1 and 2, respectively. By flowing a write current in a path from the switching section SW1 to the write wiring 1 with the switching element SW1 turned on, the magnetization of the recording magnetic section C can be recorded in a predetermined direction. Further, by supplying a write current to the path from the switching section SW2 to the write wiring 2 with the switching element SW2 turned on, the magnetization of the recording magnetic section E can be recorded in a predetermined direction.
[0087]
FIG. 14 is a schematic sectional view illustrating another modification of the solid-state magnetic element of the present embodiment. That is, FIG. 1A is a plan view thereof, and FIG. 1B is a front view thereof. Also in this figure, the same elements as those described above with reference to FIGS. 1 to 13 are denoted by the same reference numerals, and detailed description is omitted.
[0088]
In this modified example, a reference magnetic section A, a spin transfer intermediate section B, a recording magnetic section C, a spin transfer intermediate section H, and a reference magnetic section I are arranged in this order on substantially the same plane. The MR intermediate portion D is stacked on the recording magnetic portion C, and the reference magnetic portion E is stacked thereon.
[0089]
It is necessary that the size of the MR intermediate portion D is equal to or larger than the overlapping portion of the recording magnetic portion C and the reference magnetic portion E. Therefore, the MR intermediate portion D may cover the entire recording magnetic portion C, or even cover the spin transfer intermediate portion B, as long as the electrodes E1 and E2 can be connected.
[0090]
It is desirable that the magnetization direction of the reference magnetic part I be antiparallel to the reference magnetic part A. The electrode E2 is connected to the reference magnetic section I. The two spin transfer intermediate portions B and H make it possible to direct the magnetization directions of the reference magnetic portion A and the recording magnetic portion C or the recording magnetic portion C and the reference magnetic portion I in antiparallel directions.
[0091]
When electrons flow from E1 to E2 using the electrodes E1 and E2, the magnetization of the recording magnetic part C is directed in the same direction as the reference magnetic part A. Conversely, when electrons flow from the electrode E2 to the electrode E1, the magnetization of the recording magnetic part C becomes the same direction as the reference magnetic part I.
[0092]
When the switching unit, the write wiring, and the read wiring are connected to E1, E2, and E3, respectively, the same operation as that described with reference to FIG. 7B can be performed.
[0093]
FIG. 15 is a schematic sectional view showing another modification of the solid-state magnetic element of the present embodiment. That is, FIG. 1A is a plan view thereof, and FIG. 1B is a front view thereof. Also in this figure, the same elements as those described above with reference to FIGS. 1 to 14 are denoted by the same reference numerals, and detailed description is omitted.
[0094]
In this modified example, a reference magnetic section A, a spin transfer intermediate section B, a recording magnetic section C, a spin transfer intermediate section H, and a reference magnetic section I are arranged in this order on substantially the same plane. The MR intermediate portion D is stacked on the recording magnetic portion C, and the recording magnetic portion E is stacked thereon.
On both sides of the recording magnetic portion E, reference magnetic portions G and K are arranged in substantially the same plane via spin transfer intermediate portions F and J, respectively. It is necessary that the size of the MR intermediate portion D is equal to or larger than the overlapping portion of the recording magnetic portion C and the recording magnetic portion E.
[0095]
Also in this specific example, it is desirable that the magnetization direction of the reference magnetic portion G be antiparallel to the magnetization direction of the reference magnetic portion K. The two spin transfer intermediate portions B and H make it possible to direct the magnetization directions of the reference magnetic portion A and the recording magnetic portion C or the recording magnetic portion C and the reference magnetic portion I in antiparallel directions. Similarly, the two spin transfer intermediate portions F and J make it possible to direct the magnetization directions of the reference magnetic portion G and the recording magnetic portion E, or the recording magnetic portion E and the reference magnetic portion K, in antiparallel directions.
[0096]
FIG. 16 is a schematic circuit diagram of a solid-state magnetic element array using the solid-state magnetic element of the present embodiment. This solid-state magnetic element array has a structure in which a cell composed of the solid-state magnetic cell shown in FIG. 11 or FIG. 12 and two switching units 30A and 30B for selecting this cell and passing a current is connected in a matrix. Have. These cells include two bit lines BL1 and BL2 respectively connected to the two switching units 30A and 30B, word lines WL1 and WL2 connected between the reproducing unit R and the two recording units W1 and W2, Further, it is connected to a word line WL3 connected to one switching unit.
[0097]
Writing is performed as follows. First, when writing to the recording magnetic section C of the recording section W1, the switching section 30A is turned on, and current is applied to one end (the lower end in the figure) of the switching section 30A and the wiring WL1 to perform writing. The writing to the recording magnetic unit E of the recording unit W2 is performed by turning on the switching unit 30B and supplying a current to the word lines WL2 and WL3.
[0098]
On the other hand, reproduction is possible in three ways.
[0099]
As a first method, the two switching units 30A and 30B are turned ON, and the magnetic resistance between the lower end (in FIG. 16) of the switching unit 30A and the word line WL3 is detected.
[0100]
As a second method, only the switching unit 30A is turned on, and the magnetic resistance between the lower end (in FIG. 16) of the switching unit 30A and the word line WL2 is detected.
[0101]
As a third method, only the switching unit 30B is turned on, and the magnetic resistance between the word lines WL1 and WL3 is detected.
[0102]
In any of the above cases, the resistance of the reproducing unit R can be detected because the resistance of the recording magnetic units C and E is small.
[0103]
【Example】
Hereinafter, embodiments of the present invention will be described in more detail with reference to examples.
[0104]
(First embodiment)
First, as a first example of the present invention, the solid-state magnetic element of the first embodiment was manufactured.
[0105]
FIGS. 17A and 17B are schematic diagrams illustrating a cross-sectional structure of a main part of the solid-state magnetic element of the present embodiment.
[0106]
These laminated structures were produced using an ultra-high vacuum sputtering apparatus. First, the substrate was formed by forming an FET on a Si wafer by a normal CMOS process. A lower electrode film (not shown) made of tantalum (Ta) and copper (Cu) is formed thereon, and the laminated films of FIGS. And an upper electrode layer. An EB (electron beam) resist is applied on this laminated film, EB exposure is performed, and lift-off is performed. Then, the laminated film is first processed to a size of 60 nm × 240 nm, and then finely laminated using EB drawing and lift-off. A part of the film was removed until the recording layer was exposed, thereby producing the structure shown in FIG. Further, each electrode was connected to a read / write word line and an FET as shown in FIG.
[0107]
For the solid-state magnetic element, the switching transistor is turned on, first, a pulse current of minus 3 mA (milliampere) is passed between b and c to initialize the magnetization, and then a pulse current having a plus sign is set. , And the magnetization reversal of the recording magnetic portion C was detected by a change in magnetoresistance between a and c. As a result, when a write current of plus 0.2 mA flows between b and c in both of FIGS. 17A and 17B, the value of the tunnel magnetoresistance obtained between a and c does not change, and the magnetization reversal occurs. 17B. In the device having the structure shown in FIG. 17A, when a current of 0.9 mA flows between b and c, the magnetoresistance obtained between a and c shows a change. In the device having the structure of ()), when a current of plus 0.6 mA flows between bc, the magnetoresistance obtained between a and c shows a change, and it was confirmed that the magnetizations were reversed.
[0108]
Further, the solid-state magnetic elements were arrayed in a 4 × 4 matrix to produce a connected solid-state magnetic element array as shown in FIG. In this array structure, by appropriately selecting the bit line BL and the word WL, writing and reading can be performed on an arbitrary cell.
[0109]
(Second embodiment)
Next, as a second example of the present invention, the solid-state magnetic element of the second embodiment shown in FIG. 11 was manufactured. That is, in the present embodiment, the recording magnetic portions C and E are made of a magnetic film made of nickel-iron-cobalt (NiFeCo), the MR intermediate portion D is made of alumina, and the reference magnetic portions A and G are made of cobalt. Iron (CoFe) was used. Further, outside the reference magnetic parts A and G, exchange anisotropy was given by providing a laminated film composed of ruthenium (Ru) / cobalt iron (CoFe) / platinum iridium manganese (PtIrMn).
[0110]
The solid-state magnetic element of the second embodiment thus formed can perform logic processing with one element. That is, this element is, for example, a logical product (AND), a logical sum (OR), or a logical negation (OR) thereof, depending on a combination of “0” and “1” signals input to the recording magnetic unit C and the recording magnetic unit E, respectively. Various logical processes including NAND, NOR) can be performed. Further, by amplifying the reproduction output result and inputting the result to the next cell, more complicated various arithmetic processing can be performed.
[0111]
(Third embodiment)
Next, as a third embodiment of the present invention, a method of manufacturing a solid-state magnetic element having a structure in which two thin wires are crossed as illustrated in FIG. 14 will be described.
[0112]
FIG. 18 is a process chart illustrating the method for manufacturing the solid-state magnetic element of the present embodiment.
That is, first, a magnetic film made of CoFe which is a source of the reference magnetic part A, the spin transfer intermediate part B, the recording magnetic part C, the spin transfer intermediate part H, and the reference magnetic part I is formed. A resist is applied on the film, and a fine line mask is formed using an EB lithography apparatus. Then, portions other than the fine line are removed by a reactive ion etching apparatus, and a fine line 100 is formed as shown in FIG.
[0113]
The thin line is scanned with an electron beam on the lines L1 and L2 shown in FIG. 18A, and thereby, as shown in FIG. , H.
[0114]
Next, as shown in FIG. 18C, a magnetic layer 110 for the MR intermediate part D and the reference magnetic part E is formed on the thin wire 100. Then, the magnetic layer 110 is thinned by the same method as described above with reference to FIG. At this time, the thin wire 120 is formed so that the direction of the thin wire 120 is substantially perpendicular to the lower thin wire 100.
[0115]
In order to make the magnetization directions of the reference magnetic part A and the reference magnetic part I antiparallel, for example, a PtMn pad is directly laminated on the reference magnetic part I or a PtMn pad is laminated via Ru (thickness: about 1 nm). I do. Finally, the wiring was attached.
[0116]
According to the above-described method, a solid-state magnetic element having two crossed thin lines with a width of, for example, 50 nm can be formed via the MR intermediate portion D.
[0117]
The embodiments of the invention have been described with reference to examples. However, the present invention is not limited to these specific examples. For example, as for the specific dimensional relationship and material of each element constituting the solid-state magnetic element, and the shape and material of the electrode, passivation, insulating structure, and the like, those skilled in the art can appropriately select the present invention from a known range to thereby realize the present invention. The present invention is included in the scope of the present invention as long as the same operation can be performed and the same effect can be obtained.
[0118]
Components such as an antiferromagnetic layer, a ferromagnetic layer, an interlayer, and an insulating layer in the solid-state magnetic element may be formed as a single layer, or may have a structure in which two or more layers are stacked.
[0119]
In addition, all solid-state magnetic elements and solid-state magnetic element arrays that can be implemented by a person skilled in the art by appropriately changing the design based on the solid-state magnetic elements and solid-state magnetic element arrays described above as the embodiments of the present invention are similarly applied to the present invention. Belongs to the range.
[0120]
【The invention's effect】
As described in detail above, according to the present invention, a recording section capable of reliably writing at a low current by utilizing magnetization reversal by direct current driving, and a reproduction section capable of achieving high element impedance by utilizing a magnetoresistance effect. And a solid-state magnetic element having a portion.
[0121]
As a result, a cell can be selected even in the case of an array, and a magnetic memory and various logic circuits capable of high integration and low power consumption can be realized.
[Brief description of the drawings]
FIG. 1 is a schematic view illustrating a basic cross-sectional structure of a solid-state magnetic element according to a first embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating an operation of a recording unit W in the solid-state magnetic element of the present invention.
FIG. 3 is a schematic diagram illustrating an operation of a reproducing unit R in the solid-state magnetic element of the first embodiment.
FIG. 4 is a schematic view illustrating a cross section of a solid-state magnetic element using an antiferromagnetically-coupled multilayer film as an example in which a storage layer and a reference layer are multilayered.
FIG. 5 is a schematic diagram illustrating a solid-state magnetic element formed so that the widths of respective layers of the solid-state magnetic element are different from each other.
FIG. 6 is a schematic sectional view illustrating a modification of the solid-state magnetic element of the first embodiment.
FIG. 7 is a schematic sectional view illustrating a modification of the solid-state magnetic element of the first embodiment.
FIG. 8 is a schematic diagram showing an equivalent circuit of a cell constituting the solid-state magnetic element array according to the embodiment of the present invention.
FIG. 9 is a schematic circuit diagram illustrating a part of the solid-state magnetic element array according to the embodiment of the present invention.
FIG. 10 is a schematic circuit diagram showing another specific example of the solid-state magnetic element array according to the embodiment of the present invention.
FIG. 11 is a schematic diagram illustrating a cross-sectional structure of a solid-state magnetic element according to a second embodiment of the present invention.
FIG. 12 is a schematic cross-sectional view illustrating a modification of the solid-state magnetic element of the second embodiment.
FIG. 13 is a schematic sectional view showing another modification of the solid-state magnetic element of the second embodiment.
FIG. 14 is a schematic sectional view showing another modification of the solid-state magnetic element of the second embodiment.
FIG. 15 is a schematic sectional view illustrating another modification of the solid-state magnetic element of the second embodiment.
FIG. 16 is a schematic circuit diagram of a solid-state magnetic element array using the solid-state magnetic element of the second embodiment.
FIG. 17 is a schematic diagram illustrating a cross-sectional structure of a main part of a solid-state magnetic element according to an embodiment of the present invention.
FIG. 18 is a manufacturing process diagram of the solid-state magnetic element as the third embodiment of the present invention.
[Explanation of symbols]
10 solid magnetic element
20, 20A, 20B, 30A, 30B switching unit
A reference magnetic part
B spin transfer intermediate part
BL, BL1, BL2 bit lines
C recording magnetic part
DMR middle part
E reference magnetic part
E recording magnetic part
E1, E2, E3 electrodes
F spin transfer intermediate part
G reference magnetic part
M1, M2, M3 magnetization
P magnetic minute contact
R playback unit
W, W1, W2 recording unit
WL, WL1, WL2 WL3 word line

Claims (12)

A first reference magnetic unit including a first ferromagnetic material having a magnetization direction fixed in a first direction;
A second reference magnetic unit including a second ferromagnetic material whose magnetization direction is fixed in a second direction;
A recording magnetic unit provided between the first and second reference magnetic units and including a third ferromagnetic material;
A spin transfer intermediate part provided between the first reference magnetic part and the recording magnetic part,
An MR intermediate part provided between the second reference magnetic part and the recording magnetic part;
With
By passing a write current between the first reference magnetic section and the recording magnetic section, the magnetization of the third ferromagnetic material is directed substantially parallel or substantially anti-parallel to the first direction,
By flowing a sense current between the second reference magnetic section and the recording magnetic section, it is possible to detect the relative relationship between the second direction and the direction of magnetization of the third ferromagnetic material. A solid-state magnetic element characterized in that: A switching unit connected to the side of the first reference magnetic unit;
A write wiring connected to the recording magnetic unit;
Further comprising
With the switching section turned on, the write current flows through a path from the switching section to the write wiring,
2. The solid-state magnetic element according to claim 1, wherein the sense current is caused to flow in a path from the switching unit to the second reference magnetic unit with the switching unit turned on. 3. A first switching unit connected to the first reference magnetic unit,
A write / read wire connected to the recording magnetic section;
A second switching unit connected to the side of the second reference magnetic unit;
Further comprising
Flowing the write current to a path from the first switching unit to the write / read wiring while the first switching unit is turned on;
2. The solid-state magnetic element according to claim 1, wherein the sense current is caused to flow in a path from the second switching unit to the write / read wiring with the second switching unit turned on. 3. A first reference magnetic unit including a first ferromagnetic material having a magnetization direction fixed in a first direction;
A second reference magnetic unit including a second ferromagnetic material whose magnetization direction is fixed in a second direction;
An MR intermediate portion provided between the first and second reference magnetic portions;
A first recording magnetic part provided between the first reference magnetic part and the MR intermediate part and having a third ferromagnetic material;
A second recording magnetic unit provided between the second reference magnetic unit and the MR intermediate unit and having a fourth ferromagnetic material;
A first spin transfer intermediate unit provided between the first reference magnetic unit and the first recording magnetic unit;
A second spin transfer intermediate section provided between the second reference magnetic section and the second recording magnetic section;
With
By passing a write current between the first reference magnetic part and the first recording magnetic part, the magnetization of the third ferromagnetic material is oriented substantially parallel or substantially anti-parallel to the first direction. Towards
By passing a write current between the second reference magnetic section and the second recording magnetic section, the magnetization of the fourth ferromagnetic material is oriented substantially parallel or substantially anti-parallel to the second direction. Towards
By flowing a sense current between the first recording magnetic part and the second recording magnetic part, the relative relationship between the magnetization directions of the third ferromagnetic material and the fourth ferromagnetic material is obtained. A solid-state magnetic element characterized in that it is possible to detect a magnetic field. A first switching unit connected to the first reference magnetic unit,
A second switching unit connected to the side of the second reference magnetic unit;
A first write wiring connected to the first recording magnetic unit;
A second write wiring connected to the second recording magnetic unit;
Further comprising
With the first switching section turned on, the write current is caused to flow through a path from the first switching section to the first write wiring, thereby changing the magnetization of the third ferromagnetic material to the first write wiring. In a direction that is approximately parallel or approximately antiparallel to the direction,
By flowing the write current in a path from the second switching unit to the second write wiring while the second switching unit is turned on, the magnetization of the fourth ferromagnetic material is changed to the second 5. The solid-state magnetic element according to claim 4, wherein the element is oriented in a direction substantially parallel or substantially anti-parallel to the direction. By passing the write current, a spin-polarized electron current flows into the recording magnetic part, and the magnetization of the ferromagnetic material of the recording magnetic part is oriented in the substantially parallel or substantially antiparallel direction by the spin-polarized electron current. The solid-state magnetic element according to claim 1, wherein the solid-state magnetic element is directed to: The solid-state magnetic element according to claim 1, wherein when the sense current flows, a resistance changes according to a relative relationship between the directions of magnetization. The solid-state magnetic element according to claim 1, wherein the MR intermediate portion is formed of an electrically insulating material. 9. The solid-state magnetic element according to claim 1, wherein the MR intermediate portion includes a magnetic contact extending from an adjacent magnetic layer. The solid-state magnetic device according to any one of claims 1 to 9, wherein the ferromagnetic material included in the recording magnetic unit is made of a material that is softer than the ferromagnetic material included in the reference magnetic unit. element. The solid-state magnetic element according to claim 1, further comprising an antiferromagnetic layer that applies an exchange bias magnetic field to the first and second ferromagnetic materials. A plurality of solid-state magnetic elements according to any one of claims 1 to 11,
Selecting means for selecting any one of the plurality of solid-state magnetic elements and flowing the write current or the sense current;
A solid-state magnetic element array comprising:

Images