JP2007299931A - Magnetoresistance effect element and magnetic memory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To keep thermal stability even at miniaturization, and to invert the magnetization of a magnetic recording layer at low-current density. <P>SOLUTION: This magnetoresistance effect element a magnetization firmly fixed layer 8 wherein the direction of magnetization is firmly fixed; a free magnetization layer 12 wherein the direction of magnetization is variable; a tunnel insulation layer 10 formed between the magnetization firmly fixed layer and the free magnetization layer; a first anti-ferromagnetic layer 6 formed at the opposite side of the tunnel insulating layer with respect to the firmly fixed magnetization layer; and a second anti-ferromagnetic layer 14 formed at the opposite side of the tunnel insulating layer with respect to the free magnetization layer and thinner in film thickness than the first anti-ferromagnetic layer while the direction of the magnetization of the free magnetization layer can be converted by pouring an electron whose polarity is changed in spin polarization into the free magnetization layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetoresistive effect element and a magnetic memory.

  A magnetoresistive effect element using a magnetic film is used for a magnetic head, a magnetic sensor, and the like, and has been proposed to be used for a solid magnetic memory (magnetoresistance effect memory: MRAM (Magnetic Random Access Memory)). .

  The MRAM uses a tunneling magneto-resistive effect element (TMR element) in which a tunnel insulating layer is inserted between two ferromagnetic layers, one of which is a magnetic recording layer and the other is a magnetization fixed layer. It is done. Although this MRAM is attracting attention as a high-speed and nonvolatile random access memory, there is a problem that the write method using a current magnetic field has a large write current value and cannot achieve a large capacity.

In order to solve this, a writing method using a spin injection method has been proposed (for example, see Patent Document 1). This spin injection method utilizes reversal of the magnetization direction of the magnetic recording layer by injecting a spin-polarized current into the magnetic recording layer of the storage element.
US Pat. No. 6,256,223

  However, when the spin injection method is applied to the TMR element, there is a problem of element breakdown such as breakdown of the tunnel insulating layer, and there is a problem in the reliability of the element. In addition, as a final goal, in order to ensure scalability, a structure capable of reversing the direction of magnetization at a low current density without being affected by thermal fluctuation when miniaturized must be realized.

  The present invention has been made in view of the above circumstances, and has a magnetoresistive effect element that has thermal stability even when miniaturized and can reverse the magnetization of the magnetic recording layer at a low current density. An object of the present invention is to provide a magnetic memory using the.

  The magnetoresistive effect element according to the first aspect of the present invention includes a magnetization pinned layer in which the magnetization direction is pinned, a magnetization free layer having a variable magnetization direction, and between the magnetization pinned layer and the magnetization free layer. A tunnel insulating layer provided; a first antiferromagnetic layer provided on a side opposite to the tunnel insulating layer with respect to the magnetization fixed layer; and a side opposite to the tunnel insulating layer provided on the magnetization free layer. A second antiferromagnetic layer having a thickness smaller than that of the first antiferromagnetic layer, and the magnetization direction of the magnetization free layer is reversed by injecting spin-polarized electrons into the magnetization free layer. It is possible.

  The magnetization pinned layer may be a laminated film composed of a first magnetic layer / nonmagnetic layer / second magnetic layer.

  The magnetization direction of the magnetization pinned layer and the magnetization direction of the magnetization free layer may be at an angle greater than 0 degree and 45 degrees or less.

  The first antiferromagnetic layer may be any of NiMn, PtMn, and IrMn, and the second antiferromagnetic layer may be any of FeMn, IrMn, and PtMn.

A magnetic memory according to the second aspect of the present invention includes a memory cell having the magnetoresistive effect element according to any one of the above, a first wiring to which one end of the magnetoresistive effect element is electrically connected, A second wiring to which the other end of the magnetoresistive element is electrically connected;
It is provided with.

  According to a third aspect of the present invention, there is provided a magnetic memory comprising: a memory cell having the first and second magnetoresistive elements as described above; and one end of each of the first and second magnetoresistive elements. A first wiring connected to each other, a second wiring electrically connected to the other end of the first magnetoresistance effect element, and a second wiring electrically connected to the other end of the second magnetoresistance effect element. The second magnetoresistive element is arranged from the first line to the third line in the direction from the first line to the second line. It is characterized by being reverse to the layer arrangement.

  The memory cell may include a MOS transistor having one of a source / drain connected to the first wiring.

  According to the present invention, it is possible to reverse the magnetization of the magnetic recording layer at a low current density while having thermal stability even when miniaturized.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 shows a cross section of the magnetoresistive effect element according to the first embodiment of the present invention. The magnetoresistive effect element 1 of this embodiment is a bottom pin type magnetoresistive effect element, and includes a base layer 4 provided on the lower electrode 2, an antiferromagnetic layer 6 provided on the base layer 4, A magnetization pinned layer 8 formed of a ferromagnetic layer provided on the antiferromagnetic layer 6 and pinned in magnetization, a tunnel insulating layer 10 provided on the magnetization pinned layer 8, and a magnetization insulating layer provided on the tunnel insulating layer 10. A magnetization free layer (magnetic recording layer) 12 made of a ferromagnetic layer having a variable orientation, an antiferromagnetic layer 14 provided on the magnetization free layer 12, and a cap layer 16 provided on the antiferromagnetic layer 14. And an upper electrode (not shown) provided on the cap layer 16. In this embodiment, the thickness of the antiferromagnetic layer 14 in contact with the magnetization free layer 12 is smaller than the thickness of the antiferromagnetic layer 6 in contact with the magnetization fixed layer 8.

The magnetization curve when the film thickness of the ferromagnetic layer is constant and the film thickness T of the antiferromagnetic layer is 0 nm, 5 nm, and 15 nm is shown in the graph of FIG. respectively in _{g 1, g 2, g 3} . As can be seen from FIG. 2, when the film thickness T of the antiferromagnetic layer is thick (T = 15 nm), unidirectional anisotropy occurs, and when it is thin (T = 5 nm), unidirectional anisotropy does not occur. It can be seen that the coercive force is increased as compared to the case without the ferromagnetic layer (T = 0 nm). An increase in coercive force means that the thermal stability is improved even if the coercive force is reduced.

  Therefore, in the magnetoresistive effect element 1 of this embodiment, the film thickness of the antiferromagnetic layer 14 in contact with the magnetization free layer 12 is thinner than the film thickness of the antiferromagnetic layer 6 in contact with the magnetization pinned layer 8. Therefore, the magnetization fixed layer 8 is given unidirectional anisotropy by the antiferromagnetic layer 6, and the magnetization free layer 12 is given uniaxial anisotropy by the antiferromagnetic layer 14 and has a thermal stability. improves.

  Further, as in this embodiment, the antiferromagnetic layer 6 is provided in contact with the pinned magnetization layer (pinned layer) 8 and the antiferromagnetic layer 14 is provided adjacent to the magnetization free layer (free layer) 12. The angle (relative angle) formed by the magnetization (spin) directions of the magnetization pinned layer 8 and the magnetization free layer 12 can be different from 0 degrees or 180 degrees. When the relative angle of magnetization (spin) is different from 0 degrees or 180 degrees, as shown in FIG. 3, the spin injection inversion efficiency at the time of writing, that is, the MR ratio increases. The horizontal axis of FIG. 3 shows a normalized relative angle of the spins of the pinned layer and the free layer. That is, the value “0” on the horizontal axis corresponds to 180 degrees, and the value “1.0” corresponds to 0 degrees. As is clear from FIG. 3, the antiferromagnetic layer 14 having a small film thickness is compared with the magnetic moment (magnetization) of the ferromagnetic layer (magnetization pinned layer) 8 fixed by the antiferromagnetic layer 6 having a large film thickness. The angle θ (degree) of the magnetic moment (magnetization) of the pinned ferromagnetic layer (magnetization free layer) 12 is a value on the horizontal axis in FIG. 3 that is larger than 0.75 and smaller than 1, that is, 0 <θ ≦. A range of 45 degrees is preferred. Since the angle θ is a relative angle, the magnetization direction of the magnetization free layer is in the above range regardless of whether it is clockwise or counterclockwise with reference to the magnetization direction of the magnetization fixed layer 8. Don't worry.

  As a method of tilting the magnetic moment (spin moment), it is most preferable to select different materials for the antiferromagnetic layers 6 and 14. One of NiMn, PtMn, and IrMn can be used for the thick antiferromagnetic layer 6, and FeMn, IrMn, and PtMn can be used for the thin antiferromagnetic layer 14.

  If the material of the antiferromagnetic layer is different, the blocking temperature can be changed. For example, PtMn is used for the thick antiferromagnetic layer 6 and FeMn is used for the thin antiferromagnetic layer 14. Then, since the blocking temperature of PtMn is different from about 320 ° C. and the blocking temperature of FeMn is about 200 ° C., the magnetization of the magnetization pinned layer 8 is first fixed at 320 ° C. or lower during temperature drop by annealing in a magnetic field. The applied magnetic field is tilted in the direction of a desired angle at which the magnetization of the magnetization free layer 12 is desired to be tilted at a temperature of 250 ° C. or less at which the magnetization fixed layer 8 is sufficiently fixed. The angle is preferably such that the angle of the magnetic moment of the ferromagnetic layer pinned by the thin antiferromagnetic layer 14 with respect to the magnetization pinned layer 8 is inclined by 0 <θ ≦ 45 degrees. If the antiferromagnetic layer 14 made of FeMn adjacent to the magnetization free layer 12 is made thin, uniaxial anisotropy having heat resistance is given instead of unidirectional anisotropy. As combinations of antiferromagnetic layers, there are NiMn and IrMn or FeMn, PtMn and IrMn or FeMn, IrMn and FeMn, etc. Any combination of antiferromagnetic materials may be used. Even if the same antiferromagnetic material is used, the blocking temperature can be changed by changing the film thickness of the antiferromagnetic film.

  Further, as will be described in a second embodiment to be described later, when FeMn is used for the thin antiferromagnetic layer 14, the increase of the spin reflection term and the term of the damping constant are reduced, so that the spin injection magnetization with a smaller current density is achieved. The inventors have found that inversion can be achieved. Even if Ir—Mn is used, the term of spin reflection increases, which works advantageously by reducing the current density.

  In the magnetoresistive effect element according to the present embodiment, the magnetization direction of the magnetization free layer 12 is at an angle greater than 0 degree and less than or equal to 45 degrees with respect to the magnetization direction of the magnetization fixed layer 8 (hereinafter referred to as the magnetization direction). Are parallel (the same direction) state), the state in which the magnetization direction of the magnetization free layer 12 is at an angle of 135 degrees or more and less than 180 degrees relative to the magnetization direction of the magnetization pinned layer 8 (hereinafter referred to as the magnetization direction). When spin reversal is performed in a state where the magnetization direction is antiparallel (reverse direction), spin-polarized electrons are injected from the magnetization free layer 12 side. That is, a current is passed from the magnetization fixed layer 8 side to the magnetization free layer 12.

  On the other hand, when the magnetization direction of the magnetization free layer 12 is spin-reversed from the antiparallel state to the parallel state with respect to the magnetization direction of the magnetization pinned layer 8, spin-polarized electrons are transferred from the magnetization pinned layer 8 side. inject. That is, a current is passed from the magnetization free layer 12 side to the magnetization fixed layer 8.

  Although the magnetoresistive effect element 1 of the present embodiment is a bottom pin type, it may be a top pin type magnetoresistive effect element 1A as in the first modification of the present embodiment shown in FIG. . In this top pin type magnetoresistive effect element 1A, a base layer 4 is provided on a lower electrode 2, an antiferromagnetic layer 14 is provided on the base layer 4, and a magnetization free layer (magnetic) is provided on the antiferromagnetic layer 14. Recording layer) 12, a tunnel insulating layer 10 is provided on the magnetization free layer 12, a magnetization pinned layer 8 is provided on the tunnel insulation layer 10, and an antiferromagnetic layer 6 is provided on the magnetization pinned layer 8. A cap layer 16 is provided on the antiferromagnetic layer 6, and an upper electrode (not shown) is provided on the cap layer 16.

  Next, FIG. 5 shows a magnetoresistive element 1B according to a second modification of the present embodiment. The magnetoresistive effect element 1B according to the second modification is the same as the up-pin type magnetoresistive effect element 1 of the present embodiment shown in FIG. It has a laminated film, that is, a synthetic structure. Thus, it is more preferable that the magnetization pinned layer 8 has a synthetic structure because the magnetization stability is further increased.

  FIG. 6 shows a magnetoresistive effect element 1C according to the third modification of the present embodiment. The magnetoresistive effect element 1C according to the third modification is similar to the top pin type magnetoresistive effect element 1A shown in FIG. 4 except that the magnetization pinned layer 8 is formed of a laminated film having a synthetic structure, that is, a magnetic layer 8a / The non-magnetic layer 8b / magnetic layer 8c is replaced with the laminated film 8. In the magnetoresistive effect element 1C of the third modification, the stability of magnetization is further increased as in the second modification.

  Similarly to the present embodiment, the first to third modifications of the present embodiment can improve thermal stability and increase spin inversion efficiency even when miniaturized.

  In this embodiment and its modification, as a magnetic layer (ferromagnetic layer) of a magnetoresistive effect element, Ni-Fe, Co-Fe, Co-Fe-Ni alloy, or (Co, Fe, Ni)-(B ), (Co, Fe, Ni)-(B)-(P, Al, Mo, Nb, Mn) -based or amorphous materials such as Co- (Zr, Hf, Nb, Ta, Ti) films, Co-Cr- It is composed of at least one thin film selected from the group consisting of Heusler materials such as Fe—Al, Co—Cr—Fe—Si, Co—Mn—Si, Co—Mn—Al, or a multilayer film thereof. Note that the symbols (,) mean that at least one element in parentheses is included.

  In the present embodiment and its modifications, it is desirable that the magnetization pinned layer is a unidirectional anisotropy and the magnetization free layer (magnetic recording layer) is a ferromagnetic layer having uniaxial anisotropy. The thickness is preferably 0.1 nm or more and 100 nm or less. Furthermore, the thickness of the ferromagnetic layer needs to be a thickness that does not cause superparamagnetism, and is more preferably 0.4 nm or more.

  In addition, the magnetic materials constituting these ferromagnetic layers include Ag (silver), Cu (copper), Au (gold), Al (aluminum), Mg (magnesium), Si (silicon), Bi (bismuth), Ta (Tantalum), B (boron), C (carbon), O (oxygen), N (nitrogen), Pd (palladium), Pt (platinum), Zr (zirconium), Ir (iridium), W (tungsten), Mo (Molybdenum), Nb (Niobium), B (Boron) and other nonmagnetic elements can be added to adjust the magnetic properties, and other physical properties such as crystallinity, mechanical properties, and chemical properties can be adjusted. it can.

More specifically, a laminated film having a three-layer structure is used as a method for fixing the magnetic layer in one direction. As a laminated film having a three-layer structure, for example, Co (Co-Fe) / Ru (ruthenium) / Co (Co-Fe), Co (Co-Fe) / Ir (iridium) / Co (Co-Fe), Co (Co—Fe) / Os (osnium) / Co (Co—Fe), Co (Co—Fe) / Re (rhenium) / Co (Co—Fe), Co—Fe—B and other amorphous material layers / Ru ( Ruthenium) / Amorphous material layer such as Co—Fe—B, Amorphous material layer such as Co—Fe—B / Amorphous material layer such as Ir (iridium) / Co—Fe—B, Amorphous material such as Co—Fe—B Layer / amorphous material layer such as Os (osnium) / Co—Fe—B, amorphous material layer such as Co—Fe—B / amorphous material such as Re (rhenium) / Co—Fe—B Amorphous material layer such as Co-Fe-B / Ru (ruthenium) / Co-Fe, Amorphous material layer such as Co-Fe-B / Ir (iridium) / Amorphous such as Co-Fe, Co-Fe-B Material layer / As (osnium) / Amorphous material layer such as Co—Fe and Co—Fe—B / Re (rhenium) / Co—Fe. When these laminated films are used as the magnetization pinned layer, it is desirable to further provide an antiferromagnetic layer adjacent thereto. As for the antiferromagnetic layer in this case, is it possible to use Fe—Mn, Pt—Mn, Pt—Cr—Mn, Ni—Mn, Ir—Mn, NiO, Fe ₂ O ₃ or the like as described above? it can. By using this structure, the stray field from the magnetization pinned layer can be reduced (or adjusted), and the magnetization free layer (magnetic field) can be changed by changing the film thickness of the two ferromagnetic layers constituting the magnetization pinned layer. The magnetization shift of the recording layer) can be adjusted.

  The magnetic recording layer may have a two-layer structure of soft magnetic layer / ferromagnetic layer or a three-layer structure of ferromagnetic layer / soft magnetic layer / ferromagnetic layer. As the magnetic recording layer, a three-layer structure of ferromagnetic layer / nonmagnetic layer / ferromagnetic layer and a five-layer structure of ferromagnetic layer / nonmagnetic layer / ferromagnetic layer / nonmagnetic layer / ferromagnetic layer may be used. At this time, the type and film thickness of the ferromagnetic layer may be changed.

  In particular, the ferromagnetic layer close to the insulating barrier uses Co-Fe, Co-Fe-Ni, Fe-rich Ni-Fe, which has a large MR, and the ferromagnetic layer not in contact with the tunnel insulating layer uses Ni-rich Ni-Fe, Using Ni-rich Ni—Fe—Co or the like is more preferable because the switching magnetic field can be reduced while maintaining a large MR. Nonmagnetic materials include Ag (silver), Cu (copper), Au (gold), Al (aluminum), Ru (ruthenium), Os (osnium), Re (rhenium), Si (silicon), Bi (bismuth) , Ta (tantalum), B (boron), C (carbon), Pd (palladium), Pt (platinum), Zr (zirconium), Ir (iridium), W (tungsten), Mo (molybdenum), Nb (niobium) Or alloys thereof.

  Also in the magnetic recording layer, Ag (silver), Cu (copper), Au (gold), Al (aluminum), Ru (ruthenium), Os (osnium), Re (rhenium) can be used as the magnetic material constituting the magnetic recording layer. Mg (magnesium), Si (silicon), Bi (bismuth), Ta (tantalum), B (boron), C (carbon), O (oxygen), N (nitrogen), Pd (palladium), Pt (platinum) , Zr (zirconium), Ir (iridium), W (tungsten), Mo (molybdenum), Nb (niobium) and other nonmagnetic elements are added to adjust the magnetic properties, and other crystallinity and mechanical properties Various physical properties such as chemical characteristics can be adjusted.

  As a method for further reducing the write current, the magnetic recording layer to be written is composed of a multilayer film composed of at least two magnetic layers and at least one nonmagnetic layer, and the interaction between the magnetic layers via the nonmagnetic layer. It is preferable to use a magnetoresistive effect element characterized by being ferromagnetic.

When a TMR element is used as the magnetoresistive effect element, Al ₂ O ₃ (aluminum oxide), SiO ₂ can be used as a tunnel insulating layer (or dielectric layer) provided between the magnetization fixed layer and the magnetization recording layer. (Silicon oxide), MgO (magnesium oxide), AlN (aluminum nitride), Bi ₂ O ₃ (bismuth oxide), MgF ₂ (magnesium fluoride), CaF ₂ (calcium fluoride), SrTiO ₂ (titanium oxide / strontium oxide) Various insulators (dielectrics) such as AlLaO ₃ (lanthanum oxide / aluminum) and Al—N—O (aluminum oxynitride) can be used.

  These compounds do not need to have a completely accurate composition in terms of stoichiometry, and may be deficient or excessive or deficient in oxygen, nitrogen, fluorine, or the like. In addition, the thickness of the insulating layer (dielectric layer) is desirably thin enough to allow a tunnel current to flow, and in practice, desirably 10 nm or less.

Such a magnetoresistive effect element can be formed on a predetermined substrate using ordinary thin film forming means such as various sputtering methods, vapor deposition methods, and molecular beam epitaxial methods. As the substrate in this case, for example, various substrates such as Si (silicon), SiO ₂ (silicon oxide), Al ₂ O ₃ (aluminum oxide), spinel, and AlN (aluminum nitride) can be used.

  Moreover, Ta (tantalum), Ti (titanium), Pt (platinum), Pd (palladium), Au (gold), Ti (titanium) / Pt (as a base layer, a protective layer, a hard mask, etc. on the substrate. Platinum), Ta (tantalum) / Pt (platinum), Ti (titanium) / Pd (palladium), Ta (tantalum) / Pd (palladium), Cu (copper), Al (aluminum), Cu (copper), Ru ( A layer made of ruthenium), Ir (iridium), Os (osmium), or the like may be provided.

(Second Embodiment)
Next, FIG. 7 shows a magnetic memory according to the second embodiment of the present invention. The magnetic memory of this embodiment has at least one memory cell, and this memory cell is provided in the intersection region between the bit line 30 and the word line 40. The memory cell includes the bottom pin type magnetoresistive effect element 1 of the first embodiment shown in FIG. 1 and a selection transistor 60 for both writing and reading, and forms one bit. The selection transistor 60 includes a source region 61, a gate 62, and a drain region 63. One terminal of the magnetoresistive element 1 is connected to the extraction electrode 20, and the other terminal is connected to the bit line 30 through a metal hard mask or via 25. The extraction electrode 20 is connected to the source region 61 of the selection transistor 60 through the connection portion 50. The word line 40 is connected to the drain region 63 of the selection transistor 60. The selection transistor 60 is formed in the element region of the semiconductor substrate separated by the element isolation region 70 made of an insulating film.

  The configuration of the magnetoresistive effect element 1 according to the magnetic memory of this embodiment is shown in FIG. 8A. The direction of magnetization (spin moment) of the magnetization fixed layer 8 and the magnetization of the magnetic recording layer (magnetization free layer) 12 are shown. The relationship with the orientation is shown in FIG. In the magnetoresistive effect element 1, as shown in FIG. 8B, the magnetization direction (spin moment) of the magnetization fixed layer 8 and the magnetization direction of the magnetic recording layer (magnetization free layer) 12 are from 0 degrees. A predetermined angle θ of 45 degrees or less is formed. Therefore, as described in the first embodiment, the spin inversion efficiency can be increased. In addition, the film surface shape of the magnetoresistive effect element 1 is elliptical as shown in FIG.

  In addition, since the magnetic memory of the present embodiment uses the magnetoresistive effect element 1 of the first embodiment, the thermal stability can be improved even if the semiconductor memory is miniaturized, as in the first embodiment.

  Next, a magnetic memory according to a modification of the present embodiment is shown in FIG. In the magnetic memory of this modification, in the magnetic memory shown in FIG. 7, the bottom pin type magnetoresistive effect element 1 is replaced with the top pin type magnetoresistive effect element 1A according to the first modification example of the first embodiment shown in FIG. It becomes the composition. The configuration of the magnetoresistive effect element 1A according to the magnetic memory according to this modification is shown in FIG. 10A. The direction of the magnetization (spin moment) of the magnetization fixed layer 8 and the magnetization of the magnetic recording layer (magnetization free layer) 12 are shown. The relationship with the direction is shown in FIG. In this magnetoresistive effect element 1, as shown in FIG. 10B, the magnetization direction (spin moment) of the magnetization fixed layer 8 and the magnetization direction of the magnetic recording layer (magnetization free layer) 12 are from 0 degrees. A predetermined angle θ that is larger than 45 degrees is formed. For this reason, as in the second embodiment, the spin inversion efficiency can be increased. Moreover, since the magnetoresistive effect element 1A according to the first modification of the first embodiment is used, the thermal stability can be improved similarly to the first modification of the first embodiment.

  In the present embodiment or its modification, the magnetoresistive effect element 1 of the first embodiment shown in FIG. 1 or the magnetoresistive effect element 1A of the first modification shown in FIG. 4 is used as the memory element. Similar effects can be obtained by using the magnetoresistive effect element 1B according to the second modification shown in FIG. 6 or the magnetoresistive effect element 1C according to the third modification shown in FIG.

(Third embodiment)
Next, FIG. 11 shows a magnetic memory according to the third embodiment of the present invention. The magnetic memory of this embodiment has at least one memory cell, and this memory cell is provided in an intersection region between the bit lines 30 ₁ and 30 ₂ and the word line 40. The memory cell includes the bottom pin type magnetoresistive effect elements 1 ₁ and 1 _{2 of} the first embodiment shown in FIG. 1 and a selection transistor 60 for both writing and reading, and forms 1 bit. The selection transistor 60 includes a source region 61, a gate 62, and a drain region 63. One terminal of the magnetoresistive element 1 ₁ is connected to the extraction electrode 20 and the other terminal is connected to the bit line 30 ₁ through the metal hard mask or via 25 _1. The extraction electrode 20 is connected to the source region 61 of the selection transistor 60 through the connection portion 50. The word line 40 is connected to the drain region 63 of the selection transistor 60. The selection transistor 60 is formed in the element region of the semiconductor substrate separated by the element isolation region 70 made of an insulating film. Also, the magnetoresistive element 1 _2, the lead-out electrode 20, the magnetoresistance effect element 1 ₁ is provided on a surface opposite to the surface provided, one terminal via a metal hard mask or via 25 ₂ drawers connected to the electrode 20, the other terminal is connected to the bit line 30 _2. Then, the magnetoresistance effect element 1 ₂ is a layer disposed toward the extraction electrode 20 of the layer constituting the bit line 30 ₂ (stacking order) is directed from the extraction electrode 20 of the magnetoresistive element 1 ₁ to the bit line 30 ₁ layer It is comprised so that it may become reverse to layer arrangement | positioning (stacking order) of. For example, the magnetoresistive element 1 _1, drawer magnetization pinned layer 8 on the electrode 20 side is formed, the magnetization free layer in the bit line 30 ₁ side if a configuration in which (a magnetic recording layer) 12 is formed, magnetic resistance effect element 1 ₂ is the magnetization free layer 12 is formed on the lead-out electrode 20 side, and the magnetization pinned layer 8 to the bit line 30 ₂ side. The bit line 30 ₂ is not shown, it is arranged so as to be parallel to the bit lines 30 ₁ changes direction. The bit lines 30 ₁ and 30 ₂ are connected to a differential amplifier (not shown).

With such a configuration, it becomes possible to perform differential reading of the upper and lower magnetoresistive elements 1 ₁ and 1 _{2 with} the extraction electrode 20 interposed therebetween, and the reading speed can be increased.

  Similarly to the magnetic memory of the second embodiment, the magnetic memory of the present embodiment can increase the spin inversion efficiency and improve the thermal stability.

  In the present embodiment, the magnetoresistive effect element 1 of the first embodiment shown in FIG. 1 is used as the memory element, but the magnetoresistive effect element 1A of the first modification shown in FIG. 4 and the second shown in FIG. The same effect can be obtained by using the magnetoresistive effect element 1B according to the modification or the magnetoresistive effect element 1C according to the third modification shown in FIG.

  Note that the magnetic memory according to the second or third embodiment further includes a sense current control circuit, a driver, and a sinker that control a sense current that flows through the magnetoresistive element in order to read information stored in the magnetoresistive element. Has been.

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

(First embodiment)
First, as a first embodiment of the present invention, a magnetoresistive effect element 1B or 1C shown in FIG. 5 or 6 was prepared. The manufacturing procedure of this magnetoresistive element is as follows.

  First, as shown in FIG. 5 as Sample 1, a lower electrode 2 / underlayer 4 is formed on a substrate (not shown), and an antiferromagnetic layer 6 / magnetic layer 8a / nonmagnetic layer 8b / magnetic as a TMR film. A laminated film composed of the layer 8c / tunnel insulating layer 10 / magnetic layer 12 / antiferromagnetic layer 14 / Ru cap layer 16 / hard mask was formed and patterned to produce the magnetoresistive effect element 1B.

  Further, as shown in FIG. 6 as Sample 2, a lower electrode 2 / underlayer 4 is formed on a substrate (not shown), and an antiferromagnetic layer 14 / magnetic layer 12 / tunnel insulating layer 10 / magnetic as a TMR film. A laminated film composed of a cap layer 16 composed of layer 8c / nonmagnetic layer 8b / magnetic layer 8a / antiferromagnetic layer 6 / Ru / hard mask was formed and patterned to produce a magnetoresistive effect element 1C.

In this embodiment, Ta / Cu / Ta is used for the lower wiring as Sample 1 and Sample 2, and Ru is used for the underlayer. As a TMR film of sample 1, in order from the bottom, PtMn (15 nm) / CoFe (3 nm) / Ru (0.9 nm) / CoFeB (4 nm) / MgO (1.0 nm) / CoFeB (3 nm) / FeMn (5 nm) As the TMR film of sample 2, FeMn (6 nm) / CoFeB (3 nm) / MgO (1.0 nm) / CoFeB (4 nm) / Ru (0.9 nm) / CoFeB (3 nm) / IrMn (10 nm) It is used. The numbers in parentheses indicate the film thickness. Then, after annealing in a magnetic field at 360 ° C. for each of Sample 1 and Sample 2, the magnetization direction of the magnetic layer that becomes the magnetization pinned layer and the magnetization direction of the magnetization free layer are formed at 210 ° C. during cooling. A sample with an angle of about 20 degrees and a sample with no tilt were prepared. The element size has a junction size of 0.1 × 0.2 μm ² by microfabrication.

  FIG. 12 shows the result of measurement of magnetization reversal by spin injection when tilting θ = 0 degrees and 20 degrees in sample 1, and FIG. 13 shows spin injection when tilting θ = 0 degrees and 20 degrees in sample 2. The result of having measured the magnetization reversal by is shown. As shown in FIGS. 12 and 13, it can be seen that the current density for spin inversion is remarkably reduced in the sample tilted by θ = 20 degrees. This is expected from the graph shown in FIG. 3, and if the tilt angle θ is greater than 0 degree and less than 45 degrees, the current density for spin inversion decreases and the current density during writing is reduced. The For this reason, it is possible to prevent the tunnel insulating film 10 from being broken.

(Second embodiment)
As a second embodiment of the present invention, the magnetoresistive effect element 1B shown in FIG. 5 was manufactured by changing the materials of the antiferromagnetic layer 6 and the antiferromagnetic layer. The manufacturing method of the magnetoresistive effect element 1B is basically the same as that of the first embodiment.

First, as shown in FIG. 5 as Samples 3 and 4, a lower electrode 2 / underlayer 4 is formed on a substrate (not shown), and an antiferromagnetic layer 6 / magnetic layer 8a / nonmagnetic layer 8b are formed as TMR films. A magnetoresistive effect element 1B was produced by forming a layered film comprising a cap layer / hard mask composed of / magnetic layer 8c / tunnel insulating layer 10 / magnetic layer 12 / antiferromagnetic layer 14 / Ru and patterning. In this embodiment, Ta / Cu / Ta is used for the lower wiring as Sample 3 and Sample 4, and Ru is used for the underlayer. As the TMR film of Sample 3, in order from the bottom, PtMn (15 nm) / CoFe (3 nm) / Ru (0.9 nm) / CoFeB (4 nm) / MgO (1.0 nm) / CoFeB (2.5 nm) / FeMn ( 5 nm) is used. As the TMR film of sample 4, PtMn (15 nm) / CoFe (3 nm) / Ru (0.9 nm) / CoFeB (4 nm) / MgO (1.0 nm) / CoFeB (2.5 nm) / IrMn (5 nm) Used. Thereafter, after annealing in a magnetic field at 360 ° C., Sample 3 was produced at 210 ° C. when cooled, and Sample 4 was produced at 275 ° C. with a sample tilted at an angle of about 0 to 45 degrees and a sample without tilt. The element size is configured to have a junction size of 0.1 × 0.2 μm ² by fine processing.

  FIG. 14 shows the result of measurement of magnetization reversal by spin injection when θ is changed in Sample 3 and Sample 4. The horizontal axis of FIG. 14 indicates the angle θ between the magnetization direction of the magnetization pinned layer 8 and the magnetization direction of the magnetization free layer 12, and the vertical axis indicates the current density for spin inversion. As can be seen from FIG. 14, it can be seen that the current density for spin inversion of both the sample 3 and the sample 4 is remarkably reduced in the sample having the inclined θ. Further, in the case of sample 3 using FeMn as the antiferromagnetic layer 14 adjacent to the magnetization free layer 12, the current density for spin reversal is higher than in the sample 4 using IrMn as the antiferromagnetic layer 14. It was found to reduce. Further, it was found that when the tilt angle θ (degree) is larger than 0, the current density is decreased due to the rapid spin inversion, and when 0 <θ ≦ 45, the current density at the time of writing is reduced. For this reason, it is possible to prevent the tunnel insulating film 10 from being broken.

  In the second embodiment, the antiferromagnetic layer 6 uses 15 nm thick PtMn in the samples 3 and 4, the sample 3 uses 5 nm thick FeMn as the antiferromagnetic layer 14, and the sample 4 uses film thickness. Although 5 nm of IrMn is used, in sample 3 or 4, IrMn having a thickness of 10 nm may be used as the antiferromagnetic layer 6 and IrMn having a thickness of 5 nm may be used as the antiferromagnetic layer 14.

  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, a person skilled in the art is concerned with specific materials such as a ferromagnetic layer, an insulating layer, an antiferromagnetic layer, a nonmagnetic metal layer, and an electrode constituting the magnetoresistive effect element, as well as a film thickness, shape, dimension, and the like. Appropriate selections that similarly implement the present invention and obtain similar effects are also included in the scope of the present invention.

  Similarly, the structure, material, shape, and dimensions of each element constituting the magnetic memory of the present invention can be appropriately selected by those skilled in the art to implement the present invention in the same manner and obtain similar effects. It is included in the scope of the present invention.

  In addition, all magnetic memories that can be implemented by those skilled in the art based on the above-described magnetic memory as an embodiment of the present invention are also within the scope of the present invention.

  As described above in detail, according to each embodiment of the present invention, it is possible to provide a magnetoresistive effect element and a magnetic memory having thermal stability and good spin injection efficiency, and the industrial merit is great. In addition, spin inversion can be performed at a low current density, and the tunnel insulating film can be prevented from being broken.

Sectional drawing which shows the magnetoresistive effect element by 1st Embodiment of this invention. The figure which shows the film thickness dependence of the antiferromagnetic film of the magnetization curve of the laminated film which consists of a magnetization free layer and an antiferromagnetic layer. The figure which shows the relative angle dependence of the strength of a spin torque of a magnetization free layer and a magnetization pinned layer. Sectional drawing which shows the magnetoresistive effect element by the 1st modification of 1st Embodiment. Sectional drawing which shows the magnetoresistive effect element by the 2nd modification of 1st Embodiment. Sectional drawing which shows the magnetoresistive effect element by the 3rd modification of 1st Embodiment. Sectional drawing which shows the magnetic memory by 2nd Embodiment of this invention. The figure which shows the magnetoresistive effect element used for the magnetic memory of 2nd Embodiment. Sectional drawing which shows the magnetic memory by the modification of 2nd Embodiment of this invention. The figure which shows the magnetoresistive effect element used for the magnetic memory of the modification of 2nd Embodiment. Sectional drawing which shows the magnetic memory by 3rd Embodiment of this invention. The figure which shows the relationship between the current density and resistance of the sample 1 of the magnetoresistive effect element by 1st Example of this invention. The figure which shows the relationship between the current density of sample 2 of the magnetoresistive effect element by 1st Example of this invention, and resistance. The figure which shows the relationship between inclination-angle (theta) of the samples 3 and 4 of the magnetoresistive effect element by 2nd Example of this invention, and a current density.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Magnetoresistance effect element 2 Lower electrode 4 Underlayer 6 Antiferromagnetic layer 8 Magnetization pinned layer 10 Tunnel insulating layer 12 Magnetization pinned layer 14 Antiferromagnetic layer 16 Cap layer

Claims (7)

  A magnetization pinned layer with a fixed magnetization direction, a magnetization free layer with a variable magnetization direction, a tunnel insulating layer provided between the magnetization pinned layer and the magnetization free layer, and the magnetization pinned layer A first antiferromagnetic layer provided on the opposite side of the tunnel insulating layer, and a thickness smaller than the first antiferromagnetic layer provided on the opposite side of the tunnel insulating layer with respect to the magnetization free layer. And a second antiferromagnetic layer, wherein a magnetization direction of the magnetization free layer can be reversed by injecting spin-polarized electrons into the magnetization free layer.   2. The magnetoresistive effect element according to claim 1, wherein the magnetization pinned layer is a laminated film composed of a first magnetic layer / a nonmagnetic layer / a second magnetic layer.   3. The magnetoresistive element according to claim 1, wherein the magnetization direction of the magnetization pinned layer and the magnetization direction of the magnetization free layer are at an angle greater than 0 degree and not greater than 45 degrees.   The first antiferromagnetic layer is any one of NiMn, PtMn, and IrMn, and the second antiferromagnetic layer is any one of FeMn, IrMn, and PtMn. 2. A magnetoresistive element described in 1. A memory cell having the magnetoresistive effect element according to claim 1;
A first wiring to which one end of the magnetoresistive element is electrically connected;
A second wiring to which the other end of the magnetoresistive element is electrically connected;
A magnetic memory comprising: A memory cell having the first and second magnetoresistive elements according to any one of claims 1 to 4,
A first wiring connected to one end of each of the first and second magnetoresistance effect elements;
A second wiring electrically connected to the other end of the first magnetoresistive element;
A third wiring electrically connected to the other end of the second magnetoresistive element;
The layer arrangement of the first magnetoresistance effect element in the direction from the first wiring to the second wiring is the layer arrangement of the second magnetoresistance effect element from the first wiring to the third wiring. Magnetic memory characterized by being reversed.   7. The magnetic memory according to claim 5, wherein the memory cell includes a MOS transistor having one of a source / drain connected to the first wiring.

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