JP2007027493A - Magnetoresistive element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetoresistive element having no deterioration of characteristics such as the deterioration of MR characteristics by the increase of a series resistance for a heat treatment process in an element manufacturing process. <P>SOLUTION: The magnetoresistive element is used having an antiferromagnetic-substance layer 3, a fixed ferromagnetic-substance layer 11, a first non-magnetic substance layer 7, a free ferromagnetic-substance layer 8, and a first oxide layer 5. The antiferromagnetic-substance layer 3 is formed on the upper surface side of a substrate 1. The fixed ferromagnetic-substance layer 11 is formed on the antiferromagnetic-substance layer 3. The first non-magnetic substance layer 7 is formed on the fixed ferromagnetic-substance layer 11. The free ferromagnetic-substance layer 8 is formed on the first non-magnetic substance layer 7. The first oxide layer 5 is formed between the antiferromagnetic-substance layer 3 and the first non-magnetic substance layer 7 as a conductive material in a stoichiometric composition, and has a feature of a ferromagnetic substance or an antiferromagnetic substance at a temperature lower than a room temperature. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a magnetoresistive effect element and a manufacturing method thereof, and more particularly to a magnetoresistive effect element used for a memory cell of a magnetic random access memory, a reproducing magnetic head in a magnetic disk device, or a magnetic sensor, and a manufacturing method thereof.

  Magnetoresistive elements used for magnetic random access memory (hereinafter also referred to as “MRAM”), reproducing magnetic heads, and magnetic sensors are known. The magnetoresistive element changes its resistance when it senses a magnetic field. Currently, giant magnetoresistive (GMR) elements are generally used as magnetoresistive elements. The GMR element has a structure in which a conductive nonmagnetic layer such as Cu is sandwiched between ferromagnetic layers. A ferromagnetic tunnel junction (TMR) element is expected as a magnetoresistive effect element. The TMR element is promising for an MRAM and a reproducing magnetic head because it has a higher magnetoresistance change rate (MR ratio) at room temperature than a GMR element.

  A ferromagnetic tunnel junction has a structure in which an extremely thin tunnel barrier layer of several angstroms to several nanometers is sandwiched between two ferromagnetic layers. The TMR element having this junction has a high tunnel probability when the relative angle between the direction of the spontaneous magnetization of the lower ferromagnetic layer and the direction of the spontaneous magnetization of the upper ferromagnetic layer is small, and the tunnel probability is low when the relative angle is large. This phenomenon causes a magnetoresistive effect. The tunnel barrier layer is generally obtained by oxidizing a metal such as aluminum (Al).

  In order to apply this TMR element to a device that operates with a minute magnetic field such as an MRAM or a reproducing magnetic head, a laminated film called a spin valve type has been proposed. In this spin-valve type TMR laminated film, the direction of spontaneous magnetization of one ferromagnetic layer sandwiching the tunnel barrier layer can move freely with respect to an external magnetic field, and the direction of spontaneous magnetization of the other ferromagnetic layer is Fixed. A ferromagnetic layer in which the direction of spontaneous magnetization is fixed is called a fixed ferromagnetic layer, and a ferromagnetic layer in which the direction of spontaneous magnetization moves freely is called a free ferromagnetic layer. By this method, the relative angle of the magnetization direction between the direction of spontaneous magnetization of the fixed ferromagnetic layer and the direction of spontaneous magnetization of the free ferromagnetic layer can be easily changed. As a method of fixing the direction of spontaneous magnetization, a ferromagnetic layer generally serving as a fixed ferromagnetic layer is laminated on an antiferromagnetic layer, and a fixed ferromagnetic layer is formed by an exchange coupling magnetic field generated at the interface between both films. An exchange coupling method is generally used to fix the magnetization. As the antiferromagnetic layer, alloys containing Mn such as IrMn and PtMn are often used.

  In some cases, the fixed ferromagnetic layer is not a single magnetic layer, but has a three-layer structure of ferromagnetic layer / nonmagnetic layer / ferromagnetic layer. This structure is used to adjust the magnitude of the magnetic field when the magnetization of the free ferromagnetic layer is reversed. This structure is called a laminated ferri structure. At this time, ultra-thin Ru of 1.0 nm or less is used for the nonmagnetic layer.

  FIG. 1 is a cross-sectional view showing an example of a laminated structure of a conventional TMR laminated film. FIG. 1 shows an example of a TMR laminated film in which the fixed ferromagnetic layer is a single magnetic layer. The TMR laminated film 110 includes a substrate 101, a buffer layer 12, an antiferromagnetic material layer 103, a fixed ferromagnetic material layer 104, a first nonmagnetic material layer 107, a free ferromagnetic material layer 108, and a cap layer 109. Each layer may have a structure of two or more layers.

  FIG. 2 is a cross-sectional view showing an example of a laminated structure of a conventional TMR laminated film. FIG. 2 shows an example of a TMR laminated film in which the fixed ferromagnetic layer has a laminated ferri structure. The TMR multilayer film 110 includes a substrate 111, a buffer layer 112, an antiferromagnetic layer 113, a first nonmagnetic layer 117, a free ferromagnetic layer 118, a cap layer 119, a fixed ferromagnetic layer 114 / second nonmagnetic layer. A fixed layer 121 having a three-layer structure of body layer 115 / fixed ferromagnetic layer 116 is provided. Each layer may have a structure of two or more layers.

  When this TMR laminated film is applied to an MRAM or a reproducing magnetic head, the TMR laminated film needs to have heat resistance enough to withstand a process at a high temperature in the manufacturing process. For example, when applied to MRAM, it is necessary to use a process for forming a semiconductor circuit, so that heat resistance of 350 ° C. or higher is required. However, it is known that when the heat treatment is performed at such high heat, the magnetoresistance effect of the TMR laminated film is deteriorated and the MR ratio is reduced.

  One cause of this deterioration is interdiffusion at the interface of the fixed layer (fixed ferromagnetic layer) / antiferromagnetic layer. When the heat treatment temperature rises, Mn in the Mn alloy of the antiferromagnetic material layer diffuses, and when this Mn reaches the interface of the tunnel barrier layer / fixed layer, it affects the properties of the tunnel barrier and degrades the magnetoresistance effect. (E.g., S. Cardoso, et al, "Spin-tunnel-junction thermal stability and interface interdifference above 300 [deg.] C", "APPLIED PHYSICS LETTERS", vol. 76, 2000, p. 6).

  As a technique for suppressing Mn diffusion, a TMR laminated film in which an iron oxide (FeOx) layer is inserted between a first nonmagnetic layer (aluminum oxide) and a fixed layer (fixed ferromagnetic layer: CoFe) has been reported. (Zongzhi Zhang, et al, “40% tunneling magnetism after an annual at 380 ° C. for tunnel junctions with Iron-oxide interlayers”, 66 JOUL O66. With this technique, an MR ratio of 40% is obtained even by heat treatment at 380 ° C. However, this method has a narrow margin of heat treatment conditions that can provide a large MR ratio. For this reason, there are problems such as an increase in manufacturing yield and an increase in junction resistance because the oxide layer becomes a high resistance layer.

  As another technique for suppressing Mn diffusion, a configuration in which a CoFeOx layer is inserted into a fixed layer (fixed ferromagnetic layer: CoFe) and the fixed layer is CoFe / CoFeOx / CoFe is disclosed (Takao Ochiai et al. “Improvement of heat resistance of a ferromagnetic tunnel junction using CoFe / CoFeOx / CoFe for the pinned layer”, “Journal of the Japan Society of Applied Magnetics”, 27, 2003, p.307-310). With this technique, a maximum MR ratio of 47% is obtained after heat treatment at 350 ° C. However, even with this method, the margin of heat treatment conditions that can provide a large MR ratio is narrow. For example, the MR ratio is about 25% after 300 ° C. heat treatment, and the MR ratio is about 20% after 400 ° C. heat treatment. Even in this configuration, there is a problem that the oxide layer becomes a high resistance layer and the junction resistance is increased.

  As a related technique, Japanese Patent Application Laid-Open No. 2004-47583 discloses a magnetoresistive effect element, a magnetic memory, a magnetic head, and a magnetic storage device. This prior art describes that the size of the crystal grains of the antiferromagnetic layer and the thickness of the fixed ferromagnetic layer are defined to suppress the influence of grain boundary diffusion of Mn. However, there is a problem that the MR ratio is suddenly reduced from a certain heat treatment temperature or a certain heat treatment time. This problem is particularly different depending on the ultimate vacuum, the substrate temperature, the sputtering gas pressure, and the sputtering power, which are the conditions for forming each layer by sputtering. For example, when the sputtering gas thickness was increased from 0.1 Pa to 1 Pa, the MR ratio was reduced even when the heat treatment temperature was as low as about 300 ° C. That is, in order to produce a TMR film having excellent heat resistance, it is necessary to strictly control the film forming conditions, which causes a decrease in manufacturing yield and an increase in manufacturing cost. Furthermore, the case where the ferromagnetic material which has a composition shown by Formula MX which is a grain boundary control layer has an amorphous structure is disclosed. Specifically, CoFeB and NiFeB are disclosed. However, these amorphous structure films are crystallized by heat treatment at a high temperature to generate grain boundaries. In addition, even when heat treatment is performed at 300 ° C. or lower, diffusion of B occurs, and the tunnel barrier characteristics are deteriorated by the diffusion of B separately from the diffusion of Mn in the antiferromagnetic material layer.

  Japanese Patent Application Laid-Open No. 2001-6932 discloses a magnetoresistive film and a magnetic reading sensor using the same. The magnetoresistive film includes a regular antiferromagnetic layer, a fixed ferromagnetic structure bonded thereto, a first nonmagnetic conductive layer, and a free ferromagnet having at least one magnetic layer. A magnetoresistive film having a body layer portion. The fixed ferromagnetic structure has a multilayer structure including one or more sets of a three-layer structure of a first ferromagnetic layer, a second nonmagnetic layer, and a second ferromagnetic layer. The directions of spontaneous magnetization of the first and second ferromagnetic layers include parallel or parallel components. However, with this three-layer structure, it is difficult to maintain the magnetic interaction between the first ferromagnetic layer and the second ferromagnetic layer via the second nonmagnetic layer. Therefore, it is difficult for the directions of spontaneous magnetization of the first and second ferromagnetic layers to include parallel or parallel components, and thus the three-layer structure has a drawback that it does not function as a fixed layer.

  Also, a TMR laminated film in which the structure of the fixed ferromagnetic layer / antiferromagnetic layer is CoFe / CoFeTaOx / PtMn has been disclosed (Yoshiyuki Fukumoto, et al, “High thermal stability of magnetic junction weights junctions x layers "," APPLIED PHYSICS LETTERS ", vol. 84, 2004, p. 233-235). CoFeTaOx becomes an amorphous film having magnetism and can suppress Mn grain boundary diffusion. It has been observed by TEM that Mn atoms are trapped in the CoFeTaOx layer even after annealing at 380 ° C. for 1 hour. However, CoFeTaOx is a system that provides sufficient oxygen and realizes a stoichiometric composition and becomes an insulator without magnetism. To form CoFeTaOx that is magnetic and conducts metallically, the oxygen flow rate is strict. Need to control. In this method, it is difficult to form a CoFeTaOx film having a target composition, and there is a disadvantage that leads to a decrease in manufacturing yield.

Japanese Unexamined Patent Publication No. 2000-242913 discloses a magnetoresistive element and a magnetoresistive head. This magnetoresistive effect element has a configuration in which a first ferromagnetic layer, a nonmagnetic layer, a second ferromagnetic layer, an oxide antiferromagnet, and a metal antiferromagnet are sequentially stacked. The oxide ferromagnet disclosed here is a NiO, CoO, α-Fe ₂ O ₃ film. None of these are stoichiometric compositions with conductivity. In order to make these films conductive, it is necessary to reduce the amount of oxygen rather than the stoichiometric composition. For this reason, it is necessary to control the composition ratio, which may cause a reduction in manufacturing yield. In addition, since it deviates from the stoichiometric ratio, there is a possibility that the long-term stability of the film quality may be adversely affected. Furthermore, the NiO, CoO, and α-Fe ₂ O ₃ films as the oxide ferromagnets have the spontaneous magnetization direction of the fixed layer (second ferromagnetic layer) as the antiferromagnetic layer together with the metal antiferromagnet. It is stated that it is fixed. That is, this oxide ferromagnetic material is a part of the antiferromagnetic material layer.

Japanese Patent Application Laid-Open No. 2002-150514 discloses a magnetoresistive head and a magnetic recording / reproducing apparatus. In this magnetoresistive head, an antiferromagnetic film, a fixed ferromagnetic layer, a nonmagnetic film, and a free ferromagnetic layer are formed in this order. In the fixed ferromagnetic layer, an oxide layer is formed between a pair of ferromagnetic films. The thickness of the oxide layer is 5 × 10 ⁻¹⁰ m or more and 30 × 10 ⁻¹⁰ m or less. The oxide layer contains at least one element selected from Mg, Al, Si, Ca, Ti, and Zr. However, when the insulator layer is used as a diffusion preventing layer, series resistance is imparted. For this reason, the MR characteristics are deteriorated.

  JP-A-2001-352112 discloses a magnetoresistive element and a magnetoresistive head. This magnetoresistive effect element is a multilayer film in which an antiferromagnetic material layer, a fixed ferromagnetic material layer, a nonmagnetic material layer, and a free ferromagnetic material layer are sequentially laminated. The fixed ferromagnetic layer is not easily rotated by an external magnetic field. The free ferromagnetic layer can be easily rotated by an external magnetic field. In any one of the antiferromagnetic layer, the fixed ferromagnetic layer, the nonmagnetic layer, and the free ferromagnetic layer, or the antiferromagnetic layer, the fixed ferromagnetic layer, the nonmagnetic layer, and the free layer An oxide layer is formed at any interface of the ferromagnetic layer. And at least one layer selected from an antiferromagnetic layer, a fixed ferromagnetic layer, a nonmagnetic layer, and a free ferromagnetic layer (hereinafter referred to as “ω layer”) and an oxide layer, An oxygen diffusion preventing layer for suppressing the oxidation of the layer is formed. The oxygen diffusion prevention layer is selected from Au, Pt, Ag, Ru, Ni and Ni1-xMx alloy (where M is one or more of Fe, Co, Cr, Ta, 0 ≦ X <40, X is an atomic composition ratio) At least one of them may be the main component. The oxide layer may be made of an oxide whose main component is element D (where D is at least one element selected from Al, Si, Ti, Ta, Fe, Co, and Ni). In this case as well, the oxygen diffusion preventing layer becomes an insulating layer, which gives a series resistance and lowers the MR characteristics.

  Japanese Patent Application Laid-Open No. 2002-158381 discloses a ferromagnetic tunnel junction device and a manufacturing method thereof. This ferromagnetic tunnel junction element includes an antiferromagnetic layer containing Mn and an insulating layer or an amorphous magnetic layer formed between the first and second ferromagnetic layers formed on the antiferromagnetic layer. A pinned ferromagnetic layer having a structure sandwiching the layer, a tunnel barrier layer formed on the pinned ferromagnetic layer, and a free ferromagnetic layer formed on the tunnel barrier layer. The insulating layer or amorphous magnetic layer of the fixed ferromagnetic layer may have a function of preventing Mn diffusion. The insulating layer of the fixed ferromagnetic layer may be formed by exposing the first ferromagnetic layer with the fixed ferromagnetic layer to an oxidizing atmosphere, a nitriding atmosphere, or a carbonizing atmosphere.

  As a related technique, JP-A-8-94921 discloses a magnetoresistive sensor and a magnetic reproducing device. In this magnetoresistive sensor, a nonmagnetic layer is inserted between the first ferromagnetic layer and the second ferromagnetic layer, and either one of the first ferromagnetic layer and the second ferromagnetic layer has an antiferromagnetic layer. The non-magnetic layer is connected to the pair of electrodes via any one of the ferromagnetic layers, and exhibits resistance change characteristics due to the difference in magnetization direction between the first ferromagnetic layer and the second ferromagnetic layer. In the magnetoresistive sensor, the nonmagnetic layer inserted between the first ferromagnetic layer and the second ferromagnetic layer is composed of a plurality of nonmagnetic layers.

  There is a demand for a magnetoresistive effect element that does not deteriorate in characteristics with respect to a heat treatment step of 350 ° C. or more and has heat resistance. A magnetoresistive element that is relatively easy to manufacture, has a high manufacturing yield, and has a low manufacturing cost is desired. A magnetoresistive effect element that has high heat resistance, is relatively easy to manufacture, has a high manufacturing yield, and does not cause a decrease in MR characteristics due to an increase in series resistance is desired. Magnetic random access memories, magnetic heads, and magnetic storage devices that have high heat resistance, high manufacturing yield, and low manufacturing cost are desired.

JP 2004-47583 A JP 2001-6932 A JP 2000-242913 JP 2002-150514 A JP 2001-352112 A JP 2002-158381 A Japanese Patent Laid-Open No. 8-194921 S. Cardoso, et al, “Spin-tunnel-junction thermal stability and interface interdiffuse above 300 ° C.”, “APPLIED PHYSICS LETTERS”, vol. 76, 2000, p. 610-612 Zongzhi Zhang, et al, “40% tunneling magnetistance after annealing at 380 ° C. for tunnel junctions with Iron-oxide interlayers”, “JOPL IOL FOIL FOLF FOLF Ov. 89, 2001, p. 6665-6667 Takao Ochiai et al., “Improvement of heat resistance of a ferromagnetic tunnel junction using CoFe / CoFeOx / CoFe as a pinned layer”, “Journal of the Japan Society of Applied Magnetics”, 27, 2003, p. 307-310 Yoshiyuki Fukumoto, et al, “High thermal stability of magnetic tunnel junctions with oxide diffusion barrier layers,” “APPLIED PHYSICS ET. 84, 2004, p. 233-235

  An object of the present invention is to provide a magnetoresistive effect element having high heat resistance without degradation of characteristics such as a decrease in MR characteristics due to an increase in series resistance with respect to a heat treatment step in the element manufacturing process, a manufacturing method thereof, and a magnetic field thereof. An object of the present invention is to provide a magnetic random access memory, a magnetic head, and a magnetic storage device having a resistance effect element.

  Another object of the present invention is to provide a magnetoresistive effect element that is relatively easy to manufacture, has a high manufacturing yield, and is low in manufacturing cost, a manufacturing method thereof, a magnetic random access memory having the magnetoresistive effect element, a magnetic head, and a magnetic storage To provide an apparatus.

  Still another object of the present invention is that there is no deterioration in characteristics such as a decrease in MR characteristics due to an increase in series resistance with respect to a heat treatment step in an element manufacturing process, high heat resistance, relatively easy manufacturing, and manufacturing yield. It is an object of the present invention to provide a magnetoresistive effect element having a high manufacturing cost and a low manufacturing cost, a manufacturing method thereof, and a magnetic random access memory, a magnetic head, and a magnetic storage device having the magnetoresistive effect element.

  Hereinafter, means for solving the problem will be described using the numbers and symbols used in the best mode for carrying out the invention. These numbers and symbols are added with parentheses to clarify the correspondence between the description of the claims and the best mode for carrying out the invention. However, these numbers and symbols should not be used for interpreting the technical scope of the invention described in the claims.

  In order to solve the above problems, the magnetoresistive element of the present invention includes an antiferromagnetic layer (3, 24), a fixed ferromagnetic layer (11, 35), and a first nonmagnetic layer (7, 30), free ferromagnetic layers (8, 31), and first oxide layers (5, 26). The antiferromagnetic material layers (3, 24) are formed on the upper surface side of the substrates (1, 21). The fixed ferromagnetic layer (11, 35) is formed on the antiferromagnetic layer (3, 24). The first nonmagnetic layer (7, 30) is formed on the fixed ferromagnetic layer (11, 35). The free ferromagnetic layer (8, 31) is formed on the first nonmagnetic layer (7, 30). The first oxide layers (5, 26) are provided between the antiferromagnetic layers (3, 24) and the first nonmagnetic layers (7, 30). The first oxide layers (5, 26) are oxides having conductivity in the stoichiometric composition, are formed to have conductivity, and are ferromagnetic or antiferromagnetic at a temperature of room temperature or lower. .

  In order to solve the above problems, the magnetoresistive element of the present invention includes a free ferromagnetic layer (8, 31), a first nonmagnetic layer (7, 30), a fixed ferromagnetic layer (11, 35), an antiferromagnetic material layer (3, 24), and a first oxide layer (5, 26). The free ferromagnetic layer (8, 31) is formed on the upper surface side of the substrate (1, 21). The first nonmagnetic layer (7, 30) is formed on the free ferromagnetic layer (8, 31). The fixed ferromagnetic layer (11, 35) is formed on the first nonmagnetic layer (7, 30). The antiferromagnetic layers (3, 24) are formed on the fixed ferromagnetic layers (11, 35). The first oxide layers (5, 26) are formed between the antiferromagnetic layers (3, 24) and the first nonmagnetic layers (7, 30). The first oxide layers (5, 26) are oxides having conductivity in the stoichiometric composition, are formed to have conductivity, and are ferromagnetic or antiferromagnetic at a temperature of room temperature or lower. .

  In the magnetoresistive element, the first oxide layer (5) is included in the fixed ferromagnetic layer (11).

  In the magnetoresistive element, the fixed ferromagnetic layer (35) includes a first fixed ferromagnetic layer (34) formed on the antiferromagnetic layer (24) side, and a first fixed ferromagnetic layer. A second nonmagnetic layer (28) formed on the first nonmagnetic layer (30) side of (34) and a first nonmagnetic layer (30) side of the second nonmagnetic layer (28); A second fixed ferromagnetic layer (29) formed.

  In the magnetoresistive element, the first oxide layer (26) is formed between the second nonmagnetic layer (28) and the antiferromagnetic layer (24).

  In the magnetoresistive element, the first oxide layer (5) is included in the first pinned ferromagnetic layer (34).

In the magnetoresistive effect element, the first oxide layer (5, 26) includes LaTiO ₃ , CeTiO ₃ , SrVO ₃ , La _1-X Sr _X VO ₃ , CaCrO ₃ , La _1-X Sr _X MnO ₃ , _{CaFeO 3, SrFeO 3, SrCoO 3} , La 1-X Sr X CoO 3, CaRuO 3, SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, V n O It is made of at least one material selected from the group consisting of _2n-1 and La ₂ NiO ₄ .

  In the magnetoresistive effect element described above, the antiferromagnetic material layer (3, 24) is an alloy containing Mn.

  In order to solve the above-described problems, a method of manufacturing a magnetoresistive effect element according to the present invention includes a step of forming an antiferromagnetic material layer (3, 24) on the upper surface side of a substrate (1, 21), and an antiferromagnetic material. Forming a fixed ferromagnetic layer (11, 35) including a first oxide layer (5, 26) on the layer (3, 24); and on the fixed ferromagnetic layer (11, 35). Forming a first nonmagnetic layer (7, 30) and forming a free ferromagnetic layer (8, 31) on the first nonmagnetic layer (7, 30). The first oxide layers (5, 26) are oxides having conductivity in the stoichiometric composition, are formed to have conductivity, and are ferromagnetic or antiferromagnetic at a temperature of room temperature or lower. .

  In order to solve the above-described problems, a method of manufacturing a magnetoresistive effect element according to the present invention includes a step of forming a free ferromagnetic layer (8, 31) on the upper surface side of a substrate (1, 21), and a free ferromagnetic material. Forming a first nonmagnetic layer (7, 30) on the layer (8, 31); and a first oxide layer (5, 26) on the first nonmagnetic layer (7, 30). And a step of forming an antiferromagnetic layer (3, 24) on the fixed ferromagnetic layer (11, 35). The first oxide layers (5, 26) are oxides having conductivity in the stoichiometric composition, are formed to have conductivity, and are ferromagnetic or antiferromagnetic at a temperature of room temperature or lower. .

  In the method of manufacturing a magnetoresistive element, the step of forming the fixed ferromagnetic layer (35) includes the first fixed ferromagnetic layer including the first oxide layer (5) on the antiferromagnetic layer (24) side. Forming the body layer (34), forming the second nonmagnetic layer (28) on the first nonmagnetic layer (30) side of the first pinned ferromagnetic layer (34), Forming a second pinned ferromagnetic layer (29) on the first nonmagnetic layer (30) side of the nonmagnetic layer (28).

In the method of manufacturing a magnetoresistive element, the first oxide layer (5, 26) is formed of LaTiO ₃ , CeTiO ₃ , SrVO ₃ , La _1-X Sr _X VO ₃ , CaCrO ₃ , La _1-X Sr _{X MnO 3, CaFeO 3, SrFeO 3} , SrCoO 3, La 1-X Sr X CoO 3, CaRuO 3, SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, It is formed with at least one material selected from among the group consisting of _{V n O 2n-1, La} 2 NiO 4.

  In order to solve the above problems, the magnetic random access memory of the present invention comprises a plurality of memory cells (60). The plurality of memory cells (60) include a magnetoresistive effect element (55 = 10, 40) according to any one of the above items, and a selection switch (56) connected to one end of the magnetoresistive effect element (55). ).

  In order to solve the above problems, the magnetic head of the present invention includes a reproducing unit (69) and a writing unit (61). The reproducing unit (69) includes the magnetoresistive element (10, 40) described in any one of the above items, and the magnetoresistive element (10, 40) senses the magnetic field of the magnetic recording medium. The writing unit (61) is provided at a predetermined gap from the reproducing unit (69), and writes data to the magnetic recording medium.

  In order to solve the above problems, the magnetic recording apparatus of the present invention comprises a magnetic recording medium (75), a magnetic head (70), a drive unit (73), and a control unit (74). The magnetic recording medium (75) holds data. The magnetic head (70) is as described above for recording data on or reading data from the magnetic recording medium (75). The drive unit (73) drives the magnetic head (70) and the magnetic recording medium (75). The control unit (74) performs signal processing relating to data recording or reading of the magnetic recording medium (75).

  In order to solve the above problems, a magnetic sensor of the present invention includes a magnetoresistive effect element (10, 40) according to any one of the above and a first connected to one end of the magnetoresistive effect element (10, 40). A terminal (82); and a second terminal (83) connected to the other end of the magnetoresistive element (10, 40).

  According to the present invention, it is possible to obtain a magnetoresistive element having high heat resistance without deterioration of characteristics such as a decrease in MR characteristics due to an increase in series resistance with respect to a heat treatment step in an element manufacturing process. A magnetoresistive effect element that is relatively easy to manufacture, has a high manufacturing yield, and has a low manufacturing cost can be obtained.

(First embodiment)
Hereinafter, a first embodiment of a magnetoresistive effect element and a manufacturing method thereof according to the present invention will be described with reference to the accompanying drawings. FIG. 3 is a cross-sectional view showing the configuration of the magnetoresistive effect element according to the first embodiment of the present invention. The magnetoresistive element 10 includes a buffer layer 2, an antiferromagnetic material layer 3, a fixed layer 11, a first nonmagnetic material layer 7, a free ferromagnetic material layer 8, a cap layer 9, and a first oxide layer 5. is doing. The buffer layer 2 is provided on a substrate 1 such as a semiconductor substrate (elements and wirings may be provided). The antiferromagnetic material layer 3 is formed on the upper surface side of the substrate 1. Here, it is provided on the buffer layer 2. The fixed layer 11 is formed on the antiferromagnetic material layer 3. The first nonmagnetic layer 7 is provided on the fixed layer 11. The free ferromagnetic layer 8 is formed on the first nonmagnetic layer 7. The cap layer 9 is formed on the free ferromagnetic layer 8.

  The first oxide layer 5 is provided between the antiferromagnetic material layer 3 and the first nonmagnetic material layer 7. For example, it may be provided so as to be in contact with either the antiferromagnetic material layer 3 or the first nonmagnetic material layer 7. Alternatively, it may be included in the fixed layer 11. In the example of FIG. 3, an example included in the fixed layer 11 is shown. That is, the fixed layer 11 includes a fixed ferromagnetic layer 4, a first oxide layer 5, and a fixed ferromagnetic layer 6. The fixed ferromagnetic layer 4 is formed on the antiferromagnetic layer 3. The first oxide layer 5 is formed on the fixed ferromagnetic layer 4. The fixed ferromagnetic layer 6 is formed on the first oxide layer 5. Thereby, even when the material of the antiferromagnetic material layer 3 diffuses, the first oxide layer 5 becomes a barrier to the diffusion before the material reaches the first nonmagnetic material layer 7 or the vicinity thereof. Can do.

  The first oxide layer 5 is a ferromagnetic material or an anti-strong material at the operating temperature of the magnetoresistive effect element 10 (including the increased temperature when the magnetoresistive element 10 generates heat by itself or its surroundings to increase the temperature). A magnetic material is preferred. For example, if the operating temperature is room temperature or lower, the first oxide layer 5 is a ferromagnetic or antiferromagnetic material at room temperature or lower. Thus, the function of the remaining portion of the fixed layer 11 (the fixed ferromagnetic layer 4 and the fixed ferromagnetic layer 6) as a fixed layer is not disturbed, and a function as a fixed layer can be provided.

  The first oxide layer 5 is an oxide material having conductivity in the stoichiometric composition, and is preferably formed to have conductivity. Since it has conductivity, it does not become a resistance against current, so that it is possible to prevent a decrease in MR characteristics due to an increase in series resistance in the magnetoresistive element 10. A substance having a stoichiometric composition is considered to be stable during manufacturing and operation because it is considered to be in a stable state as a substance. That is, long-term deterioration can be prevented.

The first oxide layer _{5, LaTiO 3, CeTiO 3, SrVO} 3, La 1-X Sr X VO 3, CaCrO 3, La 1-X Sr X MnO 3, CaFeO 3, SrFeO 3, SrCoO 3, La 1- composed of _{X Sr X CoO 3, CaRuO 3} , SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, V n O 2n-1, La 2 NiO 4 It is made of at least one material selected from the group.

These substances are preferable in that they have the following properties.
(1) A substance having a stoichiometric composition is considered to be in a stable state as a substance. Therefore, as compared with the case of manufacturing a substance having a composition that is positively shifted from the stoichiometric composition, it is easy to manufacture since there is no need for special control such as control of the composition ratio.
(2) A substance having a stoichiometric composition is considered to be in a stable state as a substance. Therefore, once manufactured, it is considered that the film is stable during other manufacturing processes and operations. That is, the film itself does not easily deteriorate and has high reliability.
(3) In the manufacturing process of the magnetoresistive effect element 10 (example: at least 400 ° C. or less), it has high heat resistance. For this reason, the substance itself does not diffuse during the manufacturing process, which can be a barrier against the diffusion of the substance from the antiferromagnetic material layer 3.
(4) A ferromagnetic material or an antiferromagnetic material at the operating temperature assumed in the situation where the magnetoresistive element 10 is used. For this reason, in addition to not hindering the function of the remaining part of the fixed layer 11 as the fixed layer, the function as the fixed layer can be provided.
(5) It has conductivity in the stoichiometric composition. For this reason, it is possible to prevent a decrease in MR characteristics due to an increase in series resistance in the magnetoresistive element 10.

Next, a first embodiment of the method for manufacturing a magnetoresistive element of the present invention will be described.
First, the buffer layer 2 is formed on the substrate 1. Next, the antiferromagnetic material layer 3 is formed on the buffer layer 2 on the upper surface side of the substrate 1. Subsequently, the fixed ferromagnetic layer 4 is formed on the antiferromagnetic layer 3. Thereafter, the first oxide layer 5 is formed on the fixed ferromagnetic layer 4. However, the first oxide layer 5 is an oxide having conductivity in the stoichiometric composition, and is formed to have conductivity. Subsequently, the fixed ferromagnetic layer 6 is formed on the first oxide layer 5. Thereby, the fixed layer 11 (the fixed ferromagnetic layer 4, the first oxide layer 5, and the fixed ferromagnetic layer 6) is formed. Thereafter, the first nonmagnetic layer 7 is formed on the fixed layer 11. Next, the free ferromagnetic layer 8 is formed on the first nonmagnetic layer 7. Subsequently, a cap layer 9 is formed on the free ferromagnetic layer 8.

  As a film forming method, a conventionally known film forming method such as a sputtering method or a CVD method can be used. In addition to the above method, the oxide film can be formed by oxidizing a metal film after forming the metal film by a method of heat-treating the metal film in an oxidizing atmosphere or a method of processing with oxygen plasma.

  Thus, the magnetoresistive effect element 10 of FIG. 3 is manufactured.

  The magnetoresistive element 10 may be upside down. This is shown in FIG. FIG. 4 is a cross-sectional view showing a modification of the configuration of the first embodiment of the magnetoresistive element of the present invention. The magnetoresistive effect element 10a includes a buffer layer 2, a free ferromagnetic layer 8, a first nonmagnetic layer 7, a fixed layer 11, an antiferromagnetic layer 3, a cap layer 9, and a first oxide layer 5. is doing. The buffer layer 2 is provided on the substrate 1. The free ferromagnetic layer 8 is formed on the upper surface side of the substrate 1. Here, it is provided on the buffer layer 2. The first nonmagnetic layer 7 is provided on the free ferromagnetic layer 8. The fixed layer 11 is formed on the first nonmagnetic layer 7. The antiferromagnetic material layer 3 is formed on the fixed layer 11. The cap layer 9 is formed on the antiferromagnetic layer 3.

  The first oxide layer 5 is provided between the antiferromagnetic material layer 3 and the first nonmagnetic material layer 7. For example, it may be provided so as to be in contact with either the antiferromagnetic material layer 3 or the first nonmagnetic material layer 7. Alternatively, it may be included in the fixed layer 11. In the example of FIG. 4, an example included in the fixed layer 11 is shown. That is, the fixed layer 11 includes the fixed ferromagnetic layer 6, the first oxide layer 5, and the fixed ferromagnetic layer 4. The fixed ferromagnetic layer 6 is formed on the first nonmagnetic layer 7. The first oxide layer 5 is formed on the fixed ferromagnetic layer 6. The fixed ferromagnetic layer 4 is formed on the first oxide layer 5. Thereby, even when the substance of the antiferromagnetic material layer 3 diffuses, it can become a barrier for the diffusion before the substance reaches the first nonmagnetic material layer 7 or the vicinity thereof.

  Other configurations and properties of the first oxide layer 5 are the same as in the case of FIG. In this case, the same effect as in the case of FIG. 3 can be obtained.

Next, a modification of the first embodiment of the method for manufacturing a magnetoresistive element of the present invention will be described.
First, the buffer layer 2 is formed on the substrate 1. Next, the free ferromagnetic layer 8 is formed on the buffer layer 2 on the upper surface side of the substrate 1. Subsequently, the first nonmagnetic layer 7 is formed on the free ferromagnetic layer 8. Thereafter, the fixed ferromagnetic layer 6 is formed on the first nonmagnetic layer 7. Next, the first oxide layer 5 is formed on the fixed ferromagnetic layer 6. However, the first oxide layer 5 is an oxide having conductivity in the stoichiometric composition, and is formed to have conductivity. Subsequently, the fixed ferromagnetic layer 4 is formed on the first oxide layer 5. Thereby, the fixed layer 11 (the fixed ferromagnetic layer 6, the first oxide layer 5, and the fixed ferromagnetic layer 4) is formed. Thereafter, the antiferromagnetic material layer 3 is formed on the fixed layer 11. Subsequently, a cap layer 9 is formed on the antiferromagnetic material layer 3.

  As a film forming method, a conventionally known film forming method such as a sputtering method or a CVD method can be used. In addition to the above method, the oxide film can be formed by oxidizing a metal film after forming the metal film by a method of heat-treating the metal film in an oxidizing atmosphere or a method of processing with oxygen plasma.

  Thus, the magnetoresistive effect element 10a of FIG. 4 is manufactured.

  In the present invention, an oxide layer having a stoichiometric composition and conductivity between the first nonmagnetic layer 7 and the antiferromagnetic layer 3 containing Mn is strong at room temperature or lower. A first oxide layer 5 which is a magnetic material or an antiferromagnetic material is inserted as a Mn diffusion preventing layer. The Mn diffusion preventing layer preferably has a microcrystalline structure. The first oxide layer 5 having such a structure can be realized by a normal sputtering method or the like. Also, these conductive first oxide layers 5 are thermally stable. Further, since the first oxide layer 5 has conductivity, the MR characteristics are not deteriorated. In addition, since the first oxide layer 5 is ferromagnetic or antiferromagnetic at room temperature or lower, it has ferromagnetic or antiferromagnetic properties even if it is adjacent to or inserted into the magnetic film. The magnetic characteristics of the TMR film can be maintained.

(Second Embodiment)
Hereinafter, a second embodiment of the magnetoresistive effect element and the manufacturing method thereof according to the present invention will be described with reference to the accompanying drawings. FIG. 5 is a sectional view showing the configuration of the second embodiment of the magnetoresistive element of the present invention. The magnetoresistive element 40 includes a lower electrode layer 22, a buffer layer 23, an antiferromagnetic material layer 24, a fixed layer 35, a first nonmagnetic material layer 30, a free ferromagnetic material layer 31, an upper electrode layer 32, and a first electrode layer 32. An oxide layer 26 is provided. The lower electrode layer 22 is provided on a substrate 21 such as a semiconductor substrate (elements and wirings may be provided). The buffer layer 23 is provided on the lower electrode layer 22. The antiferromagnetic material layer 24 is formed on the upper surface side of the substrate 21. Here, it is provided on the buffer layer 23. The fixed layer 35 is formed on the antiferromagnetic material layer 24. The first nonmagnetic layer 30 is provided on the fixed layer 35. The free ferromagnetic layer 31 is formed on the first nonmagnetic layer 30. The upper electrode layer 32 is formed on the free ferromagnetic layer 31.

  The first oxide layer 26 is provided between the antiferromagnetic material layer 24 and the first nonmagnetic material layer 30. For example, it may be provided so as to be in contact with either the antiferromagnetic material layer 24 or the first nonmagnetic material layer 30. Alternatively, it may be included in the fixed layer 35. In the example of FIG. 3, an example included in the fixed layer 35 is illustrated. That is, the fixed layer 35 includes a fixed ferromagnetic layer 34, a second nonmagnetic layer 28, and a second fixed ferromagnetic layer 29. The fixed ferromagnetic layer 34 is formed on the antiferromagnetic layer 24. The fixed ferromagnetic layer 34 includes a first fixed ferromagnetic layer 25, a first oxide layer 26, and a first fixed ferromagnetic layer 27 stacked in this order. The second nonmagnetic layer 28 is formed on the first fixed ferromagnetic layer 27. The second pinned ferromagnetic layer 29 is formed on the second nonmagnetic layer 28. Thereby, even when the material of the antiferromagnetic material layer 24 diffuses, the first oxide layer 26 becomes a barrier to the diffusion before the material reaches the first nonmagnetic material layer 30 or the vicinity thereof. Can do.

  Here, since the material type, function, feature (property), and effect of the first oxide layer 26 are the same as those of the first oxide layer 5 in the first embodiment, the description thereof is omitted.

Next, a second embodiment of the magnetoresistive effect element manufacturing method of the present invention will be described.
First, the lower electrode layer 22 is formed on the substrate 21. Subsequently, the buffer layer 23 is formed on the lower electrode layer 22. Next, the antiferromagnetic material layer 24 is formed on the buffer layer 23 on the upper surface side of the substrate 21. Subsequently, a first pinned ferromagnetic layer 25 is formed on the antiferromagnetic layer 24. Thereafter, the first oxide layer 26 is formed on the first pinned ferromagnetic layer 25. However, the first oxide layer 26 is an oxide having conductivity in the stoichiometric composition, and is formed to have conductivity. Subsequently, a first pinned ferromagnetic layer 27 is formed on the first oxide layer 26. Next, the second nonmagnetic layer 28 is formed on the first pinned ferromagnetic layer 27. Thereafter, a second pinned ferromagnetic layer 29 is formed on the second nonmagnetic layer 28. As a result, the fixed ferromagnetic layer 34 (the first fixed ferromagnetic layer 25, the first oxide layer 26, and the first fixed ferromagnetic layer 27) is formed. At the same time, the fixed layer 35 (the fixed ferromagnetic layer 34, the second nonmagnetic layer 28, and the second fixed ferromagnetic layer 29) is formed. Thereafter, the first nonmagnetic layer 30 is formed on the fixed layer 35. Next, the free ferromagnetic layer 31 is formed on the first nonmagnetic layer 30. Subsequently, the upper electrode layer 32 is formed on the free ferromagnetic layer 31.

  As a film forming method, a conventionally known film forming method such as a sputtering method or a CVD method can be used. In addition to the above method, the oxide film can be formed by oxidizing a metal film after forming the metal film by a method of heat-treating the metal film in an oxidizing atmosphere or a method of processing with oxygen plasma.

  In this way, the magnetoresistive effect element 10 of FIG. 5 is manufactured.

  The magnetoresistive element 40 may be upside down. This is shown in FIG. FIG. 6 is a cross-sectional view showing a modification of the configuration of the second embodiment of the magnetoresistive element of the present invention. The magnetoresistive element 40a includes a lower electrode layer 22, a buffer layer 23, a free ferromagnetic layer 31, a first nonmagnetic layer 30, a fixed layer 35, an antiferromagnetic layer 24, an upper electrode layer 32, a first layer An oxide layer 26 is provided. The lower electrode layer 22 is provided on a substrate 21 such as a semiconductor substrate (elements and wirings may be provided). The buffer layer 23 is provided on the lower electrode layer 22. The free ferromagnetic layer 31 is formed on the upper surface side of the substrate 21. Here, it is provided on the buffer layer 23. The first nonmagnetic layer 30 is formed on the free ferromagnetic layer 31. The fixed layer 35 is formed on the first nonmagnetic layer 30. The antiferromagnetic material layer 24 is provided on the fixed layer 35. The upper electrode layer 32 is formed on the antiferromagnetic material layer 24.

  The first oxide layer 26 is provided between the antiferromagnetic material layer 24 and the first nonmagnetic material layer 30. For example, it may be provided so as to be in contact with either the antiferromagnetic material layer 24 or the first nonmagnetic material layer 30. Alternatively, it may be included in the fixed layer 35. In the example of FIG. 6, an example included in the fixed layer 35 is illustrated. That is, the fixed layer 35 includes a second fixed ferromagnetic layer 29, a second nonmagnetic layer 28, and a fixed ferromagnetic layer 34. The second pinned ferromagnetic layer 29 is formed on the first nonmagnetic layer 30. The second nonmagnetic layer 28 is formed on the second pinned ferromagnetic layer 29. The fixed ferromagnetic layer 34 includes a first fixed ferromagnetic layer 27, a first oxide layer 26, and a first fixed ferromagnetic layer 25 stacked in this order. The fixed ferromagnetic layer 34 is formed on the second nonmagnetic layer 28. Thereby, even when the material of the antiferromagnetic material layer 24 diffuses, the first oxide layer 26 becomes a barrier to the diffusion before the material reaches the first nonmagnetic material layer 30 or the vicinity thereof. Can do.

  Here, since the material type, function, feature (property), and effect of the first oxide layer 26 are the same as those of the first oxide layer 5 in the first embodiment, the description thereof is omitted.

Next, a second embodiment of the magnetoresistive effect element manufacturing method of the present invention will be described.
First, the lower electrode layer 22 is formed on the substrate 21. Subsequently, the buffer layer 23 is formed on the lower electrode layer 22. Next, a free ferromagnetic layer 31 is formed on the buffer layer 23 on the upper surface side of the substrate 21. Subsequently, the first nonmagnetic layer 30 is formed on the free ferromagnetic layer 31. Thereafter, the second pinned ferromagnetic layer 29 is formed on the first nonmagnetic layer 30. Subsequently, a second nonmagnetic layer 28 is formed on the second pinned ferromagnetic layer 29. Next, the first pinned ferromagnetic layer 27 is formed on the second nonmagnetic layer 28. Thereafter, the first oxide layer 26 is formed on the first pinned ferromagnetic layer 27. However, the first oxide layer 26 is an oxide having conductivity in the stoichiometric composition, and is formed to have conductivity. Next, the first pinned ferromagnetic layer 25 is formed on the first oxide layer 26. As a result, the fixed ferromagnetic layer 34 (the first fixed ferromagnetic layer 27, the first oxide layer 26, and the first fixed ferromagnetic layer 25) is formed. At the same time, the fixed layer 35 (second fixed ferromagnetic layer 29, second nonmagnetic layer 28, and fixed ferromagnetic layer 34) is formed. Thereafter, the antiferromagnetic material layer 24 is formed on the fixed layer 35. Subsequently, the upper electrode layer 32 is formed on the antiferromagnetic material layer 24.

  As a film forming method, a conventionally known film forming method such as a sputtering method or a CVD method can be used. In addition to the above method, the oxide film can be formed by oxidizing a metal film after forming the metal film by a method of heat-treating the metal film in an oxidizing atmosphere or a method of processing with oxygen plasma.

  Thus, the magnetoresistive effect element 40a of FIG. 6 is manufactured.

  Also in this embodiment, the same effect as that of the first embodiment can be obtained.

(Example)
An embodiment of the magnetoresistive element of the present invention will be described below with reference to FIG.
The substrate 21 is exemplified by, for example, a semiconductor substrate or a glass substrate on which an insulating film is formed. Electronic elements and wiring may be provided. The lower electrode layer 22 is formed on the upper surface side of the substrate 21. The material is, for example, at least one metal selected from Ta, Ti, V, Nb, Mo, Zr, Hf, Cr, Al, Pt, Ir, Au, Ru, Rh, Pd, Ag, Cu, or at least An alloy including one kind or a metal nitride such as TaN or TiN is preferable. Thereby, the lower electrode layer 22 having a small resistance value can be realized. The buffer layer 23 is formed on the lower electrode layer 22. The material is preferably NiFe, NiCr, NiFeCr, Ru, or Cu, for example. Thereby, the crystallinity of the antiferromagnetic material layer 24 laminated on the buffer layer 23 can be controlled.

  The antiferromagnetic material layer 24 is stacked on the buffer layer 64. The material is preferably an antiferromagnetic material such as Mn-X. X is at least one metal selected from Pt, Ir, Pd, Rh, Fe, Co, and Ni. Thereby, the direction of the spontaneous magnetization of the first fixed ferromagnetic layer 25 can be fixed. The first pinned ferromagnetic layer 25, the first oxide layer 26, the first pinned ferromagnetic layer 27, the second nonmagnetic layer 28, and the second pinned ferromagnetic layer 29 fix the direction of spontaneous magnetization. Acts as a layer. Each of these layers will be described later.

  The first nonmagnetic layer 30 is formed on the second pinned ferromagnetic layer 29. When the first nonmagnetic layer 30 is a tunnel barrier layer, the material of the first nonmagnetic layer 30 is not particularly limited as long as it is a nonmagnetic insulator or semiconductor. For example, at least one element selected from Mg, Ti, Zr, Hf, V, Nb, Ta, Cr, Zn, Al, Ga, Si, Ni, Fe, Co, IIa-VIa group and IIb-IVb group, It is desirable to use a compound with at least one element selected from F, O, C, N and B. In particular, an oxide or nitride of Al or Mg, nitride, or oxynitride that is excellent in insulation, can be thinned, and is excellent in stability and reproducibility is more preferable.

  The free ferromagnetic layer 31 is formed on the first nonmagnetic layer 30. The material is preferably composed mainly of at least one metal selected from, for example, Fe, Co, and Ni. These metals and alloys have a high spin polarizability and can provide a magnetoresistive element having a large MR ratio. Further, the metal or alloy contains at least one element selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Al, Si, Ir, Pt, B, C, N, and O. It may be included. By adding these elements, the magnetic properties can be improved.

  The upper electrode layer 32 is formed on the free ferromagnetic layer 31. The material is at least one metal selected from, for example, Ta, Ti, V, Nb, Mo, Zr, Hf, Cr, Al, Pt, Ir, Au, Ru, Rh, Pd, Ag, Cu or at least one kind An alloy containing any of these metals, Ta nitride, Ti nitride or the like is suitable. Thereby, an upper electrode layer having a small resistance value can be realized.

The first pinned ferromagnetic layer 25, the first oxide layer 26, the first pinned ferromagnetic layer 27, the second nonmagnetic layer 28, and the second pinned ferromagnetic layer 29 acting as the pinned layer 35 will be described. .
The first fixed ferromagnetic layer 25 and the first fixed ferromagnetic layer 27 are a lower portion and an upper portion of the fixed ferromagnetic layer 34. The material is preferably composed mainly of at least one metal selected from, for example, Fe, Co, and Ni. Further, the metal or alloy contains at least one element selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Al, Si, Ir, Pt, B, C, N, and O. It may be included. By adding these elements, the magnetic properties can be improved.

  The second fixed ferromagnetic layer 29 is preferably composed mainly of at least one metal selected from Fe, Co, and Ni, for example. Further, the metal or alloy contains at least one element selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, W, Al, Si, Ir, Pt, B, C, N, and O. It may be included. By adding these elements, the magnetic properties can be improved.

  In the second nonmagnetic layer 28, the first pinned ferromagnetic layer 25, the first pinned ferromagnetic layer 27, and the second pinned ferromagnetic layer 29 are magnetically sandwiched between the second nonmagnetic layer 28. And the coupling of the spontaneous magnetization of the first pinned ferromagnetic layer 25, the first pinned ferromagnetic layer 27, and the second pinned ferromagnetic layer 29 is antiparallel. The material of the second nonmagnetic layer 28 is preferably a metal composed of at least one element selected from Ru, Cr, Rh, Os, and Ir, or a compound thereof.

  The first oxide layer 26 is a first oxide layer made of a conductive oxide that becomes a ferromagnetic material at room temperature or lower. In the example of this figure, it is inserted between the first fixed ferromagnetic layer 25 and the first fixed ferromagnetic layer 27. The first oxide layer 26 functions as a layer that suppresses the diffusion of Mn in the antiferromagnetic material layer 24. The insertion location of the first oxide layer 26 is not limited to be between the first pinned ferromagnetic layer 25 and the first pinned ferromagnetic layer 27. If it is inserted between the antiferromagnetic material layer 24 and the first nonmagnetic material layer 30, it can function as a layer for suppressing Mn diffusion. If inserted between the first pinned ferromagnetic layer 25 and the first pinned ferromagnetic layer 27, the first pinned ferromagnetic layer 25 and the first pinned ferromagnetic layer 27 are integrated with each other. One fixed ferromagnetic layer. It is more preferable that the first oxide layer 26 is inserted between the antiferromagnetic material layer 24 and the second nonmagnetic material layer 29. When Mn diffuses into the second nonmagnetic layer 29, the coupling of spontaneous magnetization of the first pinned ferromagnetic layer 25, the first pinned ferromagnetic layer 27, and the second ferromagnetic layer 29 becomes antiparallel. This is because the effect is weakened.

  In FIG. 5, the second nonmagnetic layer 28 and the second pinned ferromagnetic layer 29 may not be used, and only the first pinned ferromagnetic layer 25 and the first pinned ferromagnetic layer 27 may be used. . Also at this time, the insertion position of the first oxide layer 26 is not limited to the position between the first pinned ferromagnetic layer 25 and the first pinned ferromagnetic layer 27, but the antiferromagnetic layer 24 and the first non-ferromagnetic layer 24. If it is inserted between the magnetic layer 30, it can act as a layer that suppresses the diffusion of Mn.

The first oxide layer _{26, LaTiO 3, CeTiO 3, SrVO} 3, La 1-X Sr X VO 3, LaCrO 3, La 1-X Sr X MnO 3, CaFeO 3, SrFeO 3, SrCoO 3, La 1- _{X Sr X CoO 3, CaRuO 3} , SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, V n O 2n-1, La which of the 2 NiO ₄ Is used.

Hereinafter, a film forming method using SrRuO ₃ will be described as an example. The lower electrode layer 22, the buffer layer 23, the antiferromagnetic layer 24, and the first pinned ferromagnetic layer 25 of FIG. 5 are formed, and the vacuum is not broken after the first pinned ferromagnetic layer 25 is formed. The first oxide layer 26 is continuously formed in vacuum by a sputtering method. At this time, the degree of vacuum before film formation in the film formation chamber is preferably 3 × 10 ⁻⁶ Pa or less. This is to reduce impurities such as hydrogen and water vapor taken into the film. After the formation of the first oxide layer 26, the first fixed ferromagnetic layer 27 is formed continuously without breaking the vacuum. It is not always necessary to perform all of the layers in FIG. 5 continuously without breaking the vacuum. A SrRuO ₃ target is used when forming the first oxide layer 26 in a vacuum by sputtering. Pure oxygen may be introduced when the film is formed.

When this conductive oxide layer (first oxide layer 26) is applied to the TMR film, the resistivity required for this conductive oxide layer changes corresponding to the resistance of the TMR film. The film thickness of the conductive oxide layer is not particularly limited, but actually it needs to be a very thin film and is about 0.1 nm to 5 nm. When the resistance R, the resistivity ρ, the film thickness d, and the film area are S, the resistance generated in the current flowing vertically through the film is R (Ω) = ρ (Ω · cm) × d (cm) / S (cm ² (1)
It is requested from. If the tunnel resistance is 100 kΩ, the thickness of the conductive oxide layer is 1 nm and the TMR element area is 0.5 μm ² , in order to suppress the influence on the MR characteristics to 1% or less of the MR ratio, Since it is good, it must be ρ <50Ω · cm. If the tunnel resistance is 5Ω, ρ <2.5 × 10 ⁻³ Ω · cm is required to suppress the influence on the MR characteristics to 1% or less of the MR ratio.

The magnetoresistive effect element of the present invention has a first oxide layer 26 that functions as a diffusion suppression layer. Due to the function of suppressing the diffusion of Mn by this layer, the diffusion of Mn into the first nonmagnetic material layer 30 accompanying the heat treatment in the element manufacturing process can be prevented. Thereby, deterioration of the characteristics of the magnetoresistive element can be prevented even by heat treatment at 350 ° C. or higher. At the same time, the manufacturing yield can be improved, and a magnetoresistive film having a low manufacturing cost can be obtained. Further, LaTiO was raised as a conductive oxide _{3, CeTiO 3, SrVO 3,} La 1-X Sr X VO 3, LaCrO 3, La 1-X Sr X MnO 3, CaFeO 3, SrFeO 3, SrCoO 3, La 1 _{-X Sr X CoO 3, CaRuO 3} , SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, V n O 2n-1, La 2 NiO 4 is approximately room temperature The resistivity at is 1 × 10 ⁻³ Ω · cm or less. Therefore, it can be applied to any resistance TMR film and does not degrade the MR characteristics.

  This technique can be applied not only to the TMR film but also to the GMR film. In this case, a conductive material is used as the first nonmagnetic layer 30 in FIG. At this time, it is preferable to use at least one element selected from nonmagnetic Cu, Au, Ag, Ru, and Cr. At this time, a single film of the above element or an alloy film may be used.

  In the first and second embodiments, the free ferromagnetic layer 31 may have a laminated ferrimagnetic structure. That is, the free ferromagnetic layer 31 may include a first magnetic layer and a second magnetic layer that are antiferromagnetically coupled via a nonmagnetic layer. Examples of the material for the first magnetic layer and the second magnetic layer include materials selected from the group consisting of Ni, Fe, Co, Mn, and compounds containing at least one of these. Examples of the film thickness of the first magnetic layer and the second magnetic layer 2 include 1.5 nm to 10 nm. Examples of the material for the nonmagnetic layer include materials selected from the group consisting of Ru, Os, Re, Ti, Cr, Rh, Cu, Pt, Pd, and compounds containing at least one of them. Examples of the film thickness of the nonmagnetic film include 0.4 nm to 3 nm.

  Such a magnetoresistive effect element having a laminated ferrimagnetic structure on the free ferromagnetic layer 31 can be similarly used for a toggle type MRAM in addition to a normal MRAM. Even in that case, the same effects as those of the first embodiment and the second embodiment can be obtained.

(Third embodiment)
The magnetoresistive effect element described in the first and second embodiments can be used for an MRAM. FIG. 7 is a block diagram showing the configuration of the embodiment of the MRAM of the present invention. The MRAM includes a memory cell array 51, a plurality of write word lines 53, a plurality of read word lines 52, a plurality of bit lines 54, an X-side selector 46, an X-side current source circuit 50, an X-side termination circuit 47, a Y-side selector 48, A Y-side current termination circuit 49, a Y-side current source circuit 42, a read current load circuit 43, and a sense amplifier 45 are provided.

  In the memory cell array 51, memory cells 60 are arranged in a matrix. The X-side selector 46 selects a desired selected read word line 52s during a read operation from a plurality of read word lines 52 and a plurality of write word lines 53 extending in the X-axis direction, and a desired selected write word line during a write operation. Select 53s. The X-side current source circuit 50 supplies a constant current during a write operation. The X-side current source termination circuit 47 terminates the plurality of write word lines 53. The Y-side selector 48 selects a desired selected bit line 54s from a plurality of bit lines 54 extending in the Y-axis direction. The read current load circuit 43 supplies a predetermined current to the selected memory cell 60 (selected cell 60s) and the reference cell memory cell 60r (reference cell) during a read operation. The Y-side current termination circuit 49 terminates the plurality of bit lines 54. The sense amplifier 45 outputs data of the selected cell 60s based on the difference between the voltage of the reference bit line 54r connected to the reference cell 60r and the voltage of the bit line 54 connected to the selected cell 60s.

  The plurality of memory cells 60 are provided corresponding to the intersections of the plurality of read word lines 52 and the plurality of write word lines 53 and the plurality of bit lines 54. The memory cell 60 includes a MOS transistor 56 that is simultaneously turned on when the memory cell 60 is selected, and a magnetoresistive element 55, which are connected in series. The magnetoresistive effect element 5 is shown as a variable resistor because the effective resistance value changes between data “1” and “0” (R and R + ΔR).

  FIG. 8 is a cross-sectional view showing the configuration of the magnetoresistive element in the embodiment of the MRAM of the present invention. The magnetoresistive effect element 55 (10) is connected to the bit line 53 through the cap layer 9 and to the MOS transistor 56 through the buffer layer 2 and the lower electrode layer 12. The magnetoresistive effect element 55 is the same as any of the magnetoresistive effect elements 10, 10a, 40, and 40a described in the first and second embodiments. Therefore, description of the details of the magnetoresistive effect element 55 is omitted. A write word line 53 is wired at a lower portion slightly away from the magnetoresistive effect element 55.

In the write operation shown in FIG. 8 (a), a write current I _WL flowing through the write word line 53, by a magnetic field formed by the meeting of a write current I _BL through the bit line 53, the spontaneous magnetization of the free ferromagnetic layer 8 orientation And the data is stored in the magnetoresistive effect element 55.

The read operation shown in FIG. 8 (b), by passing a read current I _R to the bit line 54-magnetoresistive element 55-MOS transistors 56-ground path, by measuring the resistance of the magnetoresistive element 55, Data of the magnetoresistive effect element 55 is read.

  Also in this embodiment, the same effect as in the first and second embodiments can be obtained.

(Fourth embodiment)
The magnetoresistive effect element described in the first and second embodiments can be used for a reproducing portion of a magnetic head. FIG. 9 is a cross-sectional view showing the configuration of the embodiment of the magnetic head of the present invention. The magnetic head 70 includes a writing unit 61 that writes data to the magnetic medium and a reproducing unit 69 that senses the magnetic field of the magnetic medium.

  The writing unit 61 includes a second magnetic core 62, a nonmagnetic insulator 63, a coil 64, and a first magnetic core 65. The first magnetic core 65 is provided apart from the reproducing unit 69. The second magnetic core 62 is provided away from the first magnetic core 65 so as to form a predetermined gap on the side opposite to the reproducing unit 69 with respect to the first magnetic core 65. The coil 64 is provided between the first magnetic core 65 and the second magnetic core 62 via a nonmagnetic insulator 63 that is an insulating layer. The reproducing unit 69 includes an upper shield 66, the magnetoresistive effect element 10, a lower electrode layer 67, and a nonmagnetic insulator 68. The magnetoresistive effect element 10 is the magnetoresistive effect element 10 described in the first and second embodiments, and any of the magnetoresistive effect elements 10a, 40, and 40a described in the first and second embodiments. It may be.

  In such a magnetic head 70, when data on the magnetic medium is read by the reproducing unit 69, first, the magnetic recording medium is approached to the reproducing unit 69. At this time, the direction of the spontaneous magnetization of the free ferromagnetic layer 8 is changed by the magnetic field of the magnetic recording medium, whereby the resistance of the magnetoresistive effect element 10 is changed. When a current is passed through the path of the upper shield 66, the magnetoresistive effect element 10, and the lower electrode layer 67, a change in resistance can be sensed. Thereby, the magnetic field of the magnetic recording medium can be sensed.

  Further, a magnetic recording device 78 such as an HDD (Hard Disk Drive) can be configured by applying the above magnetic head. FIG. 10 is a schematic diagram showing the configuration of the embodiment of the magnetic recording apparatus of the present invention. The magnetic recording device 78 includes a magnetic recording medium 75, a magnetic head 70, a drive unit 73, and a control unit 74. The magnetic recording medium 75 records data magnetically. The magnetic head 70 changes the magnetization of the magnetic recording medium 75 (magnetically writes data) and senses a change in magnetic field (magnetically reads data). As shown in FIG. 9, the magnetoresistive effect element 10 of the present invention is included. The drive unit 73 includes an arm unit 71 that holds the magnetic head 70 and a drive control unit 72 that drives / controls the arm unit 71 and the magnetic recording medium 75. The control unit 74 performs signal processing. By using the magnetic head 70 of the present invention as the magnetic head, a stable magnetic recording device 78 having durability against heat can be obtained.

(Fifth embodiment)
The magnetoresistive element described in the first and second embodiments can be used for a magnetic sensor. FIG. 11 is a schematic diagram showing the configuration of an embodiment of the magnetic sensor of the present invention. With reference to FIG. 11A, the magnetic sensor 80 includes an upper electrode layer 82, the magnetoresistive effect element 10, and a lower electrode layer 83. The magnetoresistive effect element 10 is the magnetoresistive effect element 10 described in the first and second embodiments, and any of the magnetoresistive effect elements 10a, 40, and 40a described in the first and second embodiments. It may be. The upper electrode layer 82 is connected to one end of the magnetoresistive effect element 10. The lower electrode layer 83 is connected to the other end of the magnetoresistive effect element 10.

  The magnetic sensor 80 is placed in an external magnetic field, the direction of spontaneous magnetization of the free ferromagnetic layer 8 is changed by the magnetic field, and the resistance of the magnetoresistive effect element 10 is changed. At this time, if a current flows between the upper electrode layer 82, the magnetoresistive effect element 10, and the lower electrode layer 83, a magnetic field can be sensed by reading the change in the resistance value. By using the magnetoresistive effect element 10 of the present invention as a magnetic sensor, a highly sensitive magnetic sensor 80 having excellent heat resistance can be realized.

  Referring to FIG. 11B, this magnetic sensor chip 90 has two magnetic sensors 80 arranged at an angle of 90 degrees. The output is taken out from the terminal 85. In this case, the direction and magnitude of the external magnetic field can be detected from the magnetic field sensed by each. Also in this case, by using the magnetoresistive element 10 of the present invention as a magnetic sensor, a highly sensitive magnetic sensor chip 90 excellent in heat resistance can be realized.

FIG. 1 is a cross-sectional view showing an example of a laminated structure of a conventional TMR laminated film. FIG. 2 is a cross-sectional view showing an example of a laminated structure of a conventional TMR laminated film. FIG. 3 is a cross-sectional view showing the configuration of the magnetoresistive effect element according to the first embodiment of the present invention. FIG. 4 is a cross-sectional view showing a modification of the configuration of the first embodiment of the magnetoresistive element of the present invention. FIG. 5 is a sectional view showing the configuration of the second embodiment of the magnetoresistive element of the present invention. FIG. 6 is a cross-sectional view showing a modification of the configuration of the second embodiment of the magnetoresistive element of the present invention. FIG. 7 is a block diagram showing the configuration of the embodiment of the MRAM according to the present invention. FIG. 8 is a cross-sectional view showing the configuration of the magnetoresistive element in the embodiment of the MRAM of the present invention. FIG. 9 is a cross-sectional view showing the configuration of the embodiment of the magnetic head of the present invention. FIG. 10 is a schematic diagram showing the configuration of the embodiment of the magnetic recording apparatus of the present invention. FIG. 11 is a schematic diagram showing the configuration of an embodiment of the magnetic sensor of the present invention.

Explanation of symbols

1, 21 Substrate 2, 23 Buffer layer 3, 24 Antiferromagnetic layer 4, 6, Fixed ferromagnetic layer 5, 26 First oxide layer 7, 30 First nonmagnetic layer 8, 31 Free ferromagnetic material Layer 9 Cap layer 10, 10a, 40, 40a, 55 Magnetoresistive element 11, 35 Fixed layer 12 Lower electrode layer 25, 27 First fixed ferromagnetic layer 28 Second nonmagnetic layer 29 Second fixed ferromagnetic Layer 22 Lower electrode layer 32 Upper electrode layer 34 Fixed ferromagnetic layer 42 Y side current source circuit 43 Read current load circuit 45 Sense amplifier 46 X side selector 47 X side termination circuit 48 Y side selector 49 Y side current termination circuit 50 X Side current source circuit 51 Memory cell array 52 Read word line 53 Write word line 54 Bit line 55 Magnetoresistive element 56 MOS transistor 60 Memory cell 61 Write Unit 62 Second magnetic core 63 Non-magnetic insulator 64 Coil 65 First magnetic core 66 Upper shield 67 Lower electrode layer 68 Magnetic insulator 69 Playback unit 70 Magnetic head 71 Arm unit 72 Drive control unit 73 Drive unit 74 Control unit 75 Magnetic Recording medium 78 Magnetic recording device 80 Magnetic sensor 82 Upper electrode layer 83 Lower electrode layer 85 Terminal 90 Magnetic sensor chip 101, 111 Substrate 102, 112 Buffer layer 103, 113 Antiferromagnetic material layer 104, 114, 116 Fixed ferromagnetic material layer 107, 117 First nonmagnetic layer 115 Second nonmagnetic layer 108, 118 Free ferromagnetic layer 109, 119 Cap layer 110, 120 TMR laminated film 121 Fixed layer

Claims (16)

An antiferromagnetic layer formed on the upper surface side of the substrate;
A fixed ferromagnetic layer formed on the antiferromagnetic layer;
A first nonmagnetic layer formed on the fixed ferromagnetic layer;
A free ferromagnetic layer formed on the first nonmagnetic layer;
A first oxide layer provided between the antiferromagnetic layer and the first nonmagnetic layer;
The first oxide layer is an oxide having conductivity in a stoichiometric composition, is formed so as to have conductivity, and is a ferromagnetic material or an antiferromagnetic material at a temperature below room temperature. . A free ferromagnetic layer formed on the upper surface of the substrate;
A first nonmagnetic layer formed on the free ferromagnetic layer;
A fixed ferromagnetic layer formed on the first nonmagnetic layer;
An antiferromagnetic layer formed on the fixed ferromagnetic layer;
A first oxide layer formed between the antiferromagnetic layer and the first nonmagnetic layer;
The first oxide layer is an oxide having conductivity in a stoichiometric composition, is formed so as to have conductivity, and is a ferromagnetic material or an antiferromagnetic material at a temperature below room temperature. . In the magnetoresistive effect element according to claim 1 or 2,
The first oxide layer is included in the fixed ferromagnetic layer. In the magnetoresistive effect element according to claim 1 or 2,
The fixed ferromagnetic layer is
A first pinned ferromagnetic layer formed on the antiferromagnetic layer side;
A second nonmagnetic layer formed on the first nonmagnetic layer side of the first pinned ferromagnetic layer;
A magnetoresistive effect element comprising: a second fixed ferromagnetic layer formed on the first nonmagnetic layer side of the second nonmagnetic layer. In the magnetoresistive effect element according to claim 4,
The first oxide layer is formed between the second nonmagnetic material layer and the antiferromagnetic material layer. The magnetoresistive effect element according to claim 5,
The first oxide layer is included in the first fixed ferromagnetic layer. Magnetoresistive element. In the magnetoresistive effect element according to any one of claims 1 to 6,
Wherein the first oxide _{layer, LaTiO 3, CeTiO 3, SrVO} 3, La 1-X Sr X VO 3, CaCrO 3, La 1-X Sr X MnO 3, CaFeO 3, SrFeO 3, SrCoO 3, La 1- composed of _{X Sr X CoO 3, CaRuO 3} , SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, V n O 2n-1, La 2 NiO 4 A magnetoresistive element formed of at least one material selected from the group. In the magnetoresistive effect element according to any one of claims 1 to 7,
A magnetoresistive effect element, wherein the antiferromagnetic material layer is an alloy containing Mn. Forming an antiferromagnetic layer on the upper surface side of the substrate;
Forming a fixed ferromagnetic layer including a first oxide layer on the antiferromagnetic layer;
Forming a first nonmagnetic layer on the fixed ferromagnetic layer;
Forming a free ferromagnetic layer on the first nonmagnetic layer, and
The first oxide layer is an oxide having conductivity in a stoichiometric composition, is formed so as to have conductivity, and is a ferromagnetic material or an antiferromagnetic material at a temperature below room temperature. Manufacturing method. Forming a free ferromagnetic layer on the upper surface of the substrate;
Forming a first nonmagnetic layer on the free ferromagnetic layer;
Forming a fixed ferromagnetic layer including a first oxide layer on the first nonmagnetic layer;
Forming an antiferromagnetic layer on the fixed ferromagnetic layer, and
The first oxide layer is an oxide having conductivity in a stoichiometric composition, is formed so as to have conductivity, and is a ferromagnetic material or an antiferromagnetic material at a temperature below room temperature. Manufacturing method. In the manufacturing method of the magnetoresistive effect element according to claim 9 or 10,
The step of forming the fixed ferromagnetic layer includes
Forming a first pinned ferromagnetic layer including the first oxide layer on the antiferromagnetic layer side;
Forming a second nonmagnetic layer on the first nonmagnetic layer side of the first pinned ferromagnetic layer;
Forming a second pinned ferromagnetic layer on the first nonmagnetic layer side of the second nonmagnetic layer. A method of manufacturing a magnetoresistive element. In the manufacturing method of the magneto-resistance effect element according to any one of claims 9 to 11,
Wherein the first oxide _{layer, LaTiO 3, CeTiO 3, SrVO} 3, La 1-X Sr X VO 3, CaCrO 3, La 1-X Sr X MnO 3, CaFeO 3, SrFeO 3, SrCoO 3, La 1- composed of _{X Sr X CoO 3, CaRuO 3} , SrRuO 3, Ca 1-X Sr X RuO 3, Ba 5/6 Sr 1/6 RuO 3, CrO 2, V n O 2n-1, La 2 NiO 4 A method for manufacturing a magnetoresistive element, wherein the magnetoresistive element is made of at least one material selected from the group. Comprising a plurality of memory cells;
The plurality of memory cells include
The magnetoresistive effect element according to any one of claims 1 to 8,
A magnetic random access memory comprising: a selection switch connected to one end of the magnetoresistive effect element. A reproducing unit comprising the magnetoresistive element according to any one of claims 1 to 8, wherein the magnetoresistive element senses a magnetic field of a magnetic recording medium,
A magnetic head comprising: a writing unit that is provided apart from the reproducing unit by a predetermined gap and writes data to a magnetic recording medium. A magnetic recording medium for holding data;
The magnetic head according to claim 14, wherein data is recorded on or read from the magnetic recording medium,
A drive unit for driving the magnetic head and the magnetic recording medium;
A magnetic recording apparatus comprising: a control unit that performs signal processing related to data recording or reading of the magnetic recording medium. The magnetoresistive effect element according to any one of claims 1 to 8,
A first terminal connected to one end of the magnetoresistive element;
A magnetic sensor comprising: a second terminal connected to the other end of the magnetoresistive element.

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