JP2015207625A - Magneto-resistance effect element and semiconductor circuit using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress degradation of element characteristic without changing magnetizing direction of a magnetizing fixed layer even if a magneto-resistance effect element is mounted on a substrate and even at the time of self-heating inside an element and momentum temperature rising.SOLUTION: In a magneto-resistance effect element, a magnetizing free layer in which magnetizing direction changes according to external magnetic field, a non-magnetic spacer layer, a magnetizing fixed layer in which magnetizing direction is fixed, and an anti-ferromagnetic layer are stacked in this order. The magneto-resistance effect element includes a bias magnetic field application part comprising a ferromagnetic body for applying a bias magnetic field to the magnetizing fixed layer in which magnetizing direction is fixed. The magnetizing fixed layer includes a first surface facing the non-magnetic spacer layer and a second surface on the side opposite to the first surface. The entire bias magnetic field application part is present on the side opposite to the magnetization free layer against a flat surface containing the second surface.

Description

  The present invention relates to a magnetoresistive effect element and a semiconductor circuit using the same.

  In recent years, the field of spintronics that utilizes the charge and spin of electrons simultaneously has attracted attention in the field of electronics that applies the charge of electrons (Non-Patent Document 1). Spintronics is a non-magnetic material consisting of a non-magnetic material, a magnetization fixed layer whose magnetization direction is fixed in a fixed direction, a magnetization free layer whose magnetization direction changes according to an external magnetic field, and a magnetization fixed layer and a magnetization free layer. It consists of a magnetic spacer layer. Due to the rapid development of magnetoresistive elements typified by giant magneto-resistance (GMR) effect and tunnel magneto-resistance (TMR) effect, hard disk drive read heads and magnetoresistive memories (MRAM) : Magnetoretic Random Access Memory) (Patent Document 1, Patent Document 2).

  Also, in the magnetoresistive effect element, when electrons, that is, spins, deliver spin angular momentum to the other magnetic layer and the direction of spin of conduction electrons changes, the angular momentum is conserved, so torque (spin transfer) is generated in the magnetic layer. (Torque) is known to occur. When this spin transfer torque is used, spin oscillation and resonance occur at a certain energy. Industrial use as devices such as high-frequency oscillation, detection, mixer, and filter using these phenomena has been proposed (Patent Document 3). It is known that the high frequency characteristics of the magnetoresistive effect element are controlled by the strength and angle of the applied magnetic field and the spin transfer torque (Non-patent Document 2).

  As an element using the high-frequency characteristics of the magnetoresistive effect element, for example, application to multi-band and active tuning, which has been studied for enhancing the functionality of portable terminals, is being studied. Specifically, in order to achieve multiband and active tuning, it is essential to realize a low-loss variable matching circuit that can be used in a high-frequency region of 1 GHz or higher, but when a varicap diode is used for the matching circuit, 1 GHz In the above high frequency region, the Q value decreases and the operating voltage increases.

  On the other hand, the present inventors have found that if a magnetoresistive effect element is used in the matching circuit, there is a possibility of surpassing a varicap diode in terms of preventing Q value reduction and increasing operating voltage, and proceeding with development. Yes.

JP 2010-262731 JP 2003-264324 A JP2010-252296

Nature, Vol. 438, no. 7066, pp. 339-342, 17 November 2005 Magune, Vol. 2, no. 6, 2007, pp282-290

  However, the conventional techniques have the following problems.

  The high-frequency characteristics of the magnetoresistive effect element can be controlled by the intensity and angle of the magnetic field applied to the element, but when considering industrial use, the high-frequency characteristics due to element characteristic degradation that occurs when the magnetoresistive effect element is mounted on a substrate as a semiconductor circuit It is necessary to suppress the decline.

  In Patent Document 1, when a magnetic field does not exist in the magnetoresistive effect element, the magnetization direction of the free layer is affected by the hard bias layers located on both sides of the magnetoresistive effect element, thereby causing the magnetization direction of the pinned layer to be different from that of the pinned layer. It is oriented vertically. When the magnetoresistive element is applied with a signal magnetic field from a predetermined area on the recording medium, the magnetic moment of the free layer can be rotated according to the direction of the signal magnetic field. Here, the free layer is synonymous with the magnetization free layer, and the pinned layer is synonymous with the magnetization fixed layer. In order for the magnetoresistive element to maintain a relatively high signal sensitivity, a horizontal bias (longitudinal bias) in a direction parallel to the recording medium is required, and the longitudinal bias reproducing head structure has a high coercive force. Hard bias layers are adjacent to both ends of the magnetoresistive element.

  However, in Patent Document 1, since the magnetic bias intensity and angle of the hard bias layer are fixed, it is possible to appropriately control the magnetic field intensity and angle applied to the magnetization free layer and use the high frequency characteristics of the magnetoresistive effect element. It may not be possible.

  In Patent Document 2, in order to improve the problem that the read head detects a leakage magnetic field from an adjacent track that expands three-dimensionally as the recording density of the hard disk drive increases, it becomes impossible to appropriately cope with the increase in recording density. In a multilayer film having an antiferromagnetic layer, a pinned magnetic layer, a nonmagnetic material layer, and a free magnetic layer, that is, a magnetoresistive effect element, the lower side of the multilayer film is more than the end faces on both sides in the track width direction of the multilayer film. A lower shield layer formed extending in the track width direction is provided, and an upper shield layer formed extending in the track width direction from both side end surfaces of the multilayer film in the track width direction is provided above the multilayer film. A structure in which a side shield layer is provided on both sides of the multilayer film in the track width direction between the lower shield layer and the upper shield layer has been proposed. That.

  However, in Patent Document 2, by providing shield layers on the top, bottom, left and right of the magnetoresistive effect element, an external magnetic field can be input to the magnetization free layer only from one direction, and the magnetic field strength and angle applied to the magnetization free layer are determined. It may become impossible to control properly.

  In Patent Document 3, as a high frequency application of a magnetoresistive effect element, it is proposed that an external magnetic field applied to the magnetoresistive effect element is controlled to give the frequency conversion device a switching function. Since the magnetoresistive effect element used in Patent Document 3 can be controlled by an external magnetic field, the magnetoresistive effect element is not provided with a hard bias layer or a shield layer. As a result, by controlling the external magnetic field, It is possible to operate a switching function that changes the ferromagnetic resonance frequency and switches the presence / absence of frequency conversion.

  However, in the element mounting process for mounting the frequency conversion device on the substrate in Patent Document 3, that is, the reflow process, the melting temperature of the solder connecting the substrate and the component is the heat treatment temperature for determining the magnetization direction of the magnetization fixed layer (hereinafter referred to as the heat treatment temperature). , The annealing temperature is close to or higher than the annealing temperature, so that the coercivity of the magnetization pinned layer is reduced in the reflow process, resulting in a change in the magnetization direction of the magnetization pinned layer, and the magnetoresistive effect. There is a possibility that the magnetic characteristics such as the magnetoresistance ratio and magnetoresistance value of the element will deteriorate. In addition to the reflow process, there is a possibility that the magnetization direction of the magnetization fixed layer changes due to self-heating due to current flowing inside the magnetoresistive effect element or instantaneous temperature rise due to generation of static electricity.

  The present invention has been made to solve such a problem. In a magnetoresistive effect element that changes high frequency characteristics by changing the external magnetic field strength and angle, an appropriate magnetic field strength and angle are applied to the magnetoresistive effect element. The magnetization direction of the magnetization fixed layer of the magnetoresistive effect element changes when an element mounting process such as a reflow process, self-heating inside the magnetoresistive effect element, or an instantaneous temperature rise occurs. An object of the present invention is to provide a magnetoresistive effect element capable of suppressing deterioration of high frequency characteristics occurring in the semiconductor device and a semiconductor circuit using the same.

In order to achieve the above object, a magnetoresistive element according to the present invention includes a magnetization free layer whose magnetization direction changes according to an external magnetic field, a magnetization fixed layer whose magnetization direction is fixed, and the magnetization free layer, A nonmagnetic spacer layer disposed between the magnetization fixed layer, a laminate having an antiferromagnetic layer, and a magnetic field applying means for applying a magnetic field to the magnetization free layer;
A magnetoresistive effect element including a bias magnetic field application unit that applies a bias magnetic field to the magnetization fixed layer in which the magnetization direction is fixed,
The magnetization fixed layer has a first surface facing the nonmagnetic spacer layer, and a second surface opposite to the first surface,
The laminated body having the antiferromagnetic layer is opposed to the second surface of the magnetization fixed layer,
The entire bias magnetic field application unit is present on the opposite side of the magnetization free layer with respect to a plane including the second surface of the magnetization fixed layer, and the bias magnetic field application unit is a ferromagnetic material.

  According to the magnetoresistive effect element having the above characteristics, even when a sudden temperature rise occurs in the element and the magnetization direction of the magnetization fixed layer changes, the magnetoresistive effect element is composed of a laminated film including a ferromagnetic layer, The magnetic field of the bias magnetic field application unit having characteristics is applied to the antiferromagnetic layer provided between the second surface of the magnetization fixed layer and the bias magnetic field application unit while maintaining the coercive force and the magnetization direction, As a result of the exchange coupling of the magnetization direction of the second surface of the magnetization pinned layer and unidirectional magnetization, the magnetization direction of the magnetization pinned layer is defined as one direction, and the characteristics of the magnetoresistive effect element can be maintained. Become.

  Further, according to the magnetoresistive effect element having the above characteristics, the bias magnetic field applying portion has a structure composed of a multilayer film in which a nonmagnetic film and a ferromagnetic layer are alternately laminated, so that the ferromagnetic layer is stronger by RKKY coupling. Because it has the magnetic properties of the magnetic material, it is possible to have a strong magnetic field, and the magnetization direction of the bias magnetic field application part defines the magnetization direction of the magnetization fixed layer, so the magnetization of the magnetization fixed layer becomes weak and the direction of magnetization is Even if the temperature changes, the magnetization direction of the magnetization fixed layer can always be kept constant, and the characteristics of the magnetoresistive effect element can be maintained.

  Furthermore, according to the magnetoresistive effect element having the above characteristics, the bias magnetic field application unit is located on the opposite side of the magnetization free layer with respect to the plane including the second surface of the magnetization fixed layer. It is applied to the antiferromagnetic layer facing the second surface of the magnetization fixed layer preferentially over the ratio applied to the magnetization free layer, and the influence of the magnetic field of the bias magnetic field application portion received by the magnetization free layer is small, It becomes possible to control the high frequency characteristics of the magnetoresistive effect element by the external magnetic field strength and angle by means.

  In the magnetoresistive effect element that achieves the above object, the minimum value of the cross-sectional area of the cross section perpendicular to the laminating direction of the magnetoresistive effect element of the bias magnetic field applying unit is the stack of magnetoresistive effect elements of the magnetization fixed layer It is characterized by being larger than the minimum value of the cross-sectional area of the cross section orthogonal to the direction.

  According to the magnetoresistive element having the above characteristics, the in-plane magnetic anisotropy can be increased because the cross-sectional area of the bias magnetic field application unit is larger than the cross-sectional area of the magnetization fixed layer, and the same cross-sectional area as that of the magnetization fixed layer. It becomes possible to improve the magnetic stability as compared with the bias magnetic field application unit.

  In the magnetoresistive effect element that achieves the above object, the bias magnetic field application unit has shape anisotropy in a direction parallel to the magnetization direction of the magnetization fixed layer.

  According to the magnetoresistive element having the above characteristics, the uniaxial magnetic anisotropy of the bias magnetic field application unit can be obtained by providing the bias magnetic field application unit with shape anisotropy, compared with the case where the cross-sectional area of the magnetization fixed layer is the same. It becomes possible to increase.

  In the magnetoresistive effect element that achieves the above object, the bias magnetic field applying unit is composed of a plurality of regions.

  According to the magnetoresistive effect element having the above characteristics, it is constituted by two or more ferromagnetic layers arranged so as to surround the magnetization fixed layer rather than the magnetic field generated by the bias magnetic field applying unit constituted by one ferromagnetic layer. A stronger magnetic field can be applied to the antiferromagnetic layer when the antiferromagnetic layer is arranged in the magnetic field generated from the biased magnetic field applying unit, and therefore, the antimagnetic layer is more strongly anti-ferromagnetic than the case where there is one bias magnetic field applying unit. The magnetic field direction of the ferromagnetic layer can be maintained.

  In a semiconductor circuit including an element package including a magnetoresistive effect element that achieves the object, a substrate, and a solder that joins the element package and the substrate, the holding force of the bias magnetic field application unit of the magnetoresistive effect element is: More than half of the maximum magnetization of the bias magnetic field application unit is maintained at a temperature at which the solder melts.

  According to the semiconductor circuit having the above characteristics, even if a sudden temperature rise occurs in the magnetoresistive effect element, half of the maximum magnetic flux of the via bias magnetic field application unit is retained, so the magnetic field direction of the bias magnetic field application unit changes. In addition, the magnetic field of the bias magnetic field application unit can define the magnetization direction of the magnetization fixed layer even at a temperature at which the coercive force of the magnetization fixed layer is reduced and the magnetization direction may change.

  According to the magnetoresistive effect element according to the present invention, the magnetoresistive effect element that changes the high-frequency characteristics by changing the external magnetic field strength and angle has a function of applying an appropriate magnetic field strength and angle to the magnetoresistive effect element. In addition, when the element mounting process such as the reflow process, the self-heating inside the magnetoresistive effect element or the instantaneous temperature rise occurs, the high frequency generated due to the change of the magnetization direction of the magnetization fixed layer of the magnetoresistive effect element A magnetoresistive effect element capable of suppressing characteristic deterioration and a semiconductor circuit using the same can be provided.

It is the schematic of the magnetoresistive effect element which concerns on the 1st Embodiment of this invention. It is the schematic of the magnetoresistive effect element which concerns on the 2nd Embodiment of this invention. It is the schematic of the magnetoresistive effect element which concerns on the 3rd Embodiment of this invention. It is a top view of the magnetoresistive effect element concerning the 3rd Embodiment of this invention. It is the schematic of the semiconductor circuit which concerns on the 4th Embodiment of this invention. It is a figure which shows the temperature characteristic of the magnetoresistive effect element which concerns on the 4th Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the constituent elements described below can be appropriately combined.

(First embodiment)
The configuration of the magnetoresistive effect element according to the first embodiment of the present invention will be described with reference to FIG.

  In FIG. 1, the magnetoresistive effect element 101 includes a buffer layer (not shown), a bias magnetic field application unit 14, an antiferromagnetic layer 13, a magnetization fixed layer 12, a nonmagnetic spacer layer 11, and a magnetization free layer 10 on the lower electrode 2. The cap layer (not shown) and the upper electrode 1 are laminated in this order, and the magnetization fixed layer 12 has a surface 17 facing the nonmagnetic spacer layer 11 and a surface 18 facing the antiferromagnetic layer 13. The bias magnetic field applying unit 14 is located on the opposite side of the magnetization free layer 10 with respect to the plane 19 including the plane 18 where the magnetization fixed layer 12 faces the antiferromagnetic layer 13.

  There is a magnetic field applying means 16 around the magnetoresistive effect element 101. The magnetic field applying means 16 has a structure for applying a uniform and uniform magnetic field to the entire magnetization free layer. The magnetic field applying means 16 is composed of a permanent magnet or an electromagnet. By providing a plurality of magnetic field applying means 16 and applying a magnetic field to the magnetoresistive effect element 101, a magnetic field can be applied at 360 degrees.

  It is also conceivable that the film stacked between the lower electrode 2 and the upper electrode 1 is upside down. In this case, the magnetoresistive element 101 has a cap layer, a magnetization free layer 10, The nonmagnetic spacer layer 11, the magnetization fixed layer 12, the antiferromagnetic layer 13, the bias magnetic field application unit 14, the buffer layer, and the upper electrode 1 are laminated in this order. The bias magnetic field application unit 14 includes the magnetization fixed layer 12 and the antiferromagnetic layer. 13 is located on the side opposite to the magnetization free layer 10 with respect to the plane 19 including the surface 18 facing the surface 13.

  The periphery of the magnetoresistive effect element 101 is covered with an insulating layer 15, and current flows in the stacking direction of the magnetoresistive effect element 101, that is, in the direction of the upper electrode 1 and the lower electrode 2. At this time, since the thickness of the nonmagnetic spacer layer 11 is very small, from several to several nanometers, a tunnel current flows through the nonmagnetic spacer layer 11. Although the magnetization direction of the magnetization free layer 10 changes depending on the magnetic field strength and the magnetic field angle of the magnetic field applying means 16, the magnetization direction of the magnetization fixed layer 12 does not change.

  By changing the magnetic field strength and angle of the magnetic field applying means 16, the magnetization direction of the magnetization free layer 10 changes, and as a result, the angle formed between the magnetization free layer 10 and the magnetization fixed layer 12 changes. When the magnetization direction of the magnetization free layer 10 and the magnetization direction of the magnetization fixed layer 12 are close to each other, the tunnel probability increases and the electrical resistance decreases. Further, when the magnetization direction of the magnetization free layer 10 and the magnetization direction of the magnetization fixed layer 12 are close to each other, the tunnel probability is low and the electric resistance is increased.

  The magnetization fixed layer 12 in the magnetoresistive effect element 101 may be a laminated film with a nonmagnetic spacer layer sandwiched in addition to a ferromagnetic single layer structure. The first ferromagnetic layer 12a and the second ferromagnetic layer 12b are strongly magnetically coupled by RKKY coupling, and the magnetization directions of the ferromagnetic layers 12a and 12b are opposite to each other.

  The antiferromagnetic layer 13 disposed at a position facing the second surface 18 of the magnetization fixed layer 12 exists to make the magnetic field strength of the magnetization fixed layer 12 stronger, and the magnetization fixed layer 12b and the antiferromagnetic layer 13 is exchange-coupled on the opposite surface.

  Here, although the antiferromagnetic layer 13 influences the determination of the magnetization direction of the fixed magnetization layer 12, the entire antiferromagnetic layer 13 has zero magnetization, and thus forms each of the magnetizations of the magnetization free layer. It does not function as a magnetization fixed layer.

  Next, each layer of the magnetoresistive effect element 101 will be described.

There is a substrate under the lower electrode 2 (not shown), and a silicon substrate having a smooth surface is prepared. This silicon substrate has an outer diameter of 150 mm and a thickness of about 2 mm, and can be purchased as a commercial product. The substrate may be made of a material such as Altic (Al ₂ O ₃ .TiC), glass (SiO _x ), or carbon (C). Further, a silicon substrate or a glass substrate whose substrate surface has been thermally oxidized in advance can be used as the substrate. An insulating layer may be formed on the substrate surface. The insulating layer functions to prevent a capacitor component from being generated between the substrate 1 and the lower electrode 2 due to a current flowing from the lower electrode 2 to be described later into the substrate 1, thereby causing a high-frequency transmission loss. The insulating layer is made of a nonmagnetic insulating material such as aluminum oxide (Al ₂ O ₃ ) or silicon oxide (SiO ₂ ) by, for example, sputtering or IBD (ion beam deposition). The thickness is preferably about 0.05 μm to 10 μm.

  The lower electrode 2 serves as a pair of electrodes with the upper electrode 1 described later. That is, a function as a pair of electrodes for flowing current in the direction intersecting the surface of each layer constituting the element, for example, the direction perpendicular to the surface of each layer constituting the element (stacking direction). have.

  The structure of the lower electrode 2 and the upper electrode 1 is, for example, a film composed of a single composition of Ta, Cu, Au, AuCu, Ru, or a composition of any two or more of the above materials by sputtering, IBD, or the like. Composed. The film thicknesses of the lower electrode 2 and the upper electrode 1 are preferably about 0.05 μm to 5 μm.

  The buffer layer, the antiferromagnetic layer 13, the magnetization fixed layer 12, the nonmagnetic spacer layer 11, the magnetization free layer 10, and the cap layer are formed using, for example, a sputtering film formation apparatus.

  The buffer layer is a layer for blocking the crystallinity of the lower electrode 2 and controlling the orientation and grain size of the antiferromagnetic layer 13, and in particular, exchange coupling between the antiferromagnetic layer 13 and the magnetization fixed layer 12. For example, a film of Ta and NiCr, a laminated film of Ta and Ru, or an alloy film is preferable. The film thickness of the buffer layer is preferably about 2 nm to 6 nm, for example.

  The antiferromagnetic layer 13 is a layer intended to impart unidirectional magnetic anisotropy to the magnetization fixed layer 12 by exchange coupling with the magnetization fixed layer 12.

  The antiferromagnetic layer 13 includes, for example, an antiferromagnetic material containing Mn and at least one element selected from the group consisting of Pt, Ru, Rh, Pd, Ni, Cu, Ir, Cr, and Fe. Consists of The Mn content is preferably 35 at% to 95 at%. Among the antiferromagnetic materials, non-heat-treating antiferromagnetic materials that exhibit antiferromagnetism without inducing heat treatment and induce exchange coupling with the ferromagnetic material, and exhibit antiferromagnetism by heat treatment There is a heat treatment type antiferromagnetic material. In the present embodiment, any of the above types may be used. Examples of non-heat-treating antiferromagnetic materials include alloys composed of RuRhMn, FeMn, IrMn, and the like. Examples of the heat-treated antiferromagnetic material include alloys composed of PtMn, NiMn, PtRhMn, and the like. In order to align the direction of exchange coupling even in the non-heat treated antiferromagnetic material, heat treatment is usually performed. The film thickness of the antiferromagnetic layer 13 is preferably about 4 nm to 30 nm.

  The magnetization pinned layer 12 is formed on an antiferromagnetic layer 13 that performs a pinning action to increase the magnetic field strength of the magnetization pinned layer 12. The magnetization fixed layer 12 has a configuration in which a second ferromagnetic layer 12b, a nonmagnetic intermediate layer (not shown), and a first ferromagnetic layer 12a are sequentially stacked from the side close to the antiferromagnetic layer 13, that is, A synthetic pinned layer is formed.

  The first ferromagnetic layer 12a and the second ferromagnetic layer 12b are configured to include a ferromagnetic layer made of a ferromagnetic material containing, for example, Co or Fe. The first ferromagnetic layer 12a and the second ferromagnetic layer 12b are antiferromagnetically coupled and fixed so that the magnetization directions of the first ferromagnetic layer 12a and the second ferromagnetic layer 12b are opposite to each other.

  It is preferable that the first ferromagnetic layer 12a and the second ferromagnetic layer 12b have, for example, a CoFe alloy, a laminated structure of CoFe alloys having different compositions, and a laminated structure of a CoFeB alloy and a CoFe alloy. The thickness of the second ferromagnetic layer 12b is preferably 1 nm to 7 nm, and the thickness of the first ferromagnetic layer 12a is preferably about 2 nm to 10 nm. The first ferromagnetic layer 12a may include a Heusler alloy.

  In order to perform the annealing process for determining the magnetization direction of the magnetization fixed layer 12, it is necessary to increase the Ir and Mn alloys of the antiferromagnetic layer 13 to a blocking temperature at which covalent bonding is eliminated, and the temperature is about 200 ° C. to 260 ° C. It is.

  When the blocking temperature of the antiferromagnetic layer 13 is reached, the magnetic moment fluctuates violently and the uniaxial anisotropy disappears. Therefore, the magnetization direction tends to change due to the influence of an external magnetic field. The 13 ferromagnetic coupling is weakened. Since the second ferromagnetic layer 12b facing the antiferromagnetic layer 13 has weak exchange coupling with the antiferromagnetic layer 13, the strength of the magnetization fixed layer 12 becomes weak.

  The nonmagnetic intermediate layer sandwiched between the magnetization fixed layers 12 is made of, for example, a nonmagnetic material containing at least one selected from the group of Ru, Rh, Ir, Re, Cr, Zr, and Cu. The film thickness of the nonmagnetic intermediate layer is, for example, about 0.35 nm to 1.0 nm. The nonmagnetic intermediate layer is provided to fix the magnetization of the first ferromagnetic layer 12a and the magnetization of the second ferromagnetic layer 12b in opposite directions. The “magnetization is opposite to each other” is a wide concept including the case where these two magnetizations differ from each other by 180 ° ± 20 ° without being narrowly interpreted as being narrowly limited.

  The nonmagnetic spacer layer 11 is a layer for obtaining the magnetoresistance effect by causing the magnetization of the magnetization fixed layer 12 and the magnetization of the magnetization free layer 11 to interact.

  Examples of the nonmagnetic spacer layer 11 include an insulator, a semiconductor, and a conductor.

In the case of applying an insulator as the nonmagnetic spacer layer 11, Al ₂ O ₃ or magnesium oxide can be used. Magnesium oxide is preferably a uniformly formed single crystal MgO (001), and has a high magnetoresistance by adjusting the nonmagnetic spacer layer 11 and the magnetization free layer 10 so that a coherent tunnel effect can be expected. It is more preferable that the rate of change is obtained. The thickness of the insulator is preferably about 0.5 nm to 2.0 nm.

When a semiconductor is applied as the nonmagnetic spacer layer 11, a configuration in which a first nonmagnetic metal layer, a semiconductor oxide layer, and a second nonmagnetic metal layer are sequentially stacked from the magnetization fixed layer 12 side is preferable. Examples of the first nonmagnetic metal layer include Cu and Zn. The film thickness of the first nonmagnetic metal layer is preferably about 0.1 nm to 1.2 nm. Examples of the semiconductor oxide layer include zinc oxide (ZnO), indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), indium tin oxide (ITO), GaO, and Ga ₂ O _3. Gallium oxide alloy. The thickness of the semiconductor oxide layer is preferably about 1.0 nm to 4.0 nm. Examples of the second nonmagnetic metal layer include Zn, an alloy of Zn and Ga, a film of Zn and GaO, and an alloy of Cu, Cu and Ga. The thickness of the second nonmagnetic metal layer is preferably about 0.1 nm to 1.2 nm.

  When a conductor is applied as the nonmagnetic spacer layer 11, Cu and Ag are exemplified. The thickness of the conductor is preferably about 1 nm to 4 nm.

  The magnetization free layer 10 is a layer whose magnetization direction is changed by an external magnetic field or spin-polarized electrons.

  When selecting a material having an easy axis in the in-plane direction, the magnetization free layer 10 is formed of a film having a thickness of about 1 nm to 10 nm made of, for example, CoFe, CoFeB, CoFeSi, CoMnGe, CoMnSi, CoMnAl, or the like. . A soft magnetic film having a thickness of about 1 nm to 9 nm made of, for example, NiFe may be added to the film as a magnetostriction adjusting layer.

  In the case of selecting a material having an easy axis in the direction perpendicular to the film surface, the magnetization free layer 10 is, for example, Co, Co / nonmagnetic spacer layer laminated film, CoCr alloy, Co multilayer film, CoCrPt alloy, FePt alloy. , SmCo alloy containing rare earth, TbFeCo alloy, Heusler alloy.

  Further, a high spin polarization material may be inserted between the laminated structure of the magnetization free layer 10 and the nonmagnetic spacer layer 11. This makes it possible to obtain a high magnetoresistance change rate.

  Examples of the high spin polarization material include a CoFe alloy and a CoFeB alloy. The thickness of each of the CoFe alloy and the CoFeB alloy is preferably 0.2 nm or more and 1 nm or less.

  Further, induced magnetic anisotropy may be introduced by applying a constant magnetic field in the direction perpendicular to the film surface when the magnetization free layer 10 is formed.

  The cap layer is a layer intended to protect the magnetization free layer 10 from oxidation and etching. For example, a laminated film of Ru, Ta, Ru and Ta is preferable, and the film thickness is preferably about 2 nm to 10 nm.

After the cap layer is formed, an annealing process for fixing the magnetization of the magnetization fixed layer 12 is performed. The annealing treatment is preferably performed at a vacuum degree of 1.0 × 10 ⁻³ Pa or less, a temperature of 250 ° C. to 300 ° C., a time of 1 hour to 5 hours, and an applied magnetic field of 3 kOe to 10 kOe.

  After annealing, well-known photoresist patterning, ion beam etching, and the like are performed, and the shape of the magnetoresistive effect element 100 viewed from above is patterned into a circle, an ellipse, a rectangle, and the like. The dimension is preferably 150 nm or less.

  The bias magnetic field application unit 14 is made of a ferromagnetic material containing Co or Fe. The bias magnetic field application unit 14 preferably has a CoFe alloy, a laminated structure of CoFe alloys having different compositions, and a laminated structure of a CoFeB alloy and a CoFe alloy, and the entire bias magnetic field application region is a ferromagnetic material. . The thickness of the bias magnetic field application unit 14 is preferably about 1 nm to 50 nm. The bias magnetic field application unit 14 may include a Heusler alloy.

  The magnetization direction of the opposing surface of the magnetic field generated from the bias magnetic field application unit 14 and the antiferromagnetic layer 13 is determined by exchange coupling, and the antiferromagnetic layer 13 and the second ferromagnetic film 12b of the magnetization fixed layer 12 are opposed to each other. The surface 18 is exchange-coupled, and the magnetization direction of the second ferromagnetic film 12b is determined by RKKY coupling with the first ferromagnetic film 12a.

  Further, when the bias magnetic field applying part is a laminated film with the nonmagnetic spacer layer sandwiched between them, the laminated ferromagnetic layers can generate a stronger magnetic field than in the case of a single layer structure due to RKKY coupling.

  The bias magnetic field applying unit 14 formed of a laminated body having a ferromagnetic material is opposite to the magnetization free layer 10 with respect to the plane 19 including the surface 18 where the magnetization fixed layer 12 faces the antiferromagnetic layer 13. Since the bias magnetic field applying unit 14 and the magnetization free layer 10 are located at a distance from each other, the magnetic field generated by the bias magnetic field applying unit 14 is more antiferromagnetic than the ratio applied to the magnetization free layer 10. 13 is large, and the magnetization free layer 10 is not substantially affected by the bias magnetic field application unit 14.

(Second Embodiment)
The configuration of the magnetoresistive effect element according to the second embodiment of the present invention will be described with reference to FIG.

  As shown in the magnetoresistive effect element 102 shown in FIG. 2, the structure of the magnetoresistive effect element 101 shown in the first embodiment is a cross section 14a of the bias magnetic field applying unit 14 perpendicular to the stacking direction of the magnetoresistive effect element 102. The minimum value of the cross-sectional area is larger than the minimum value of the cross-sectional area of the cross section 12c of the magnetization fixed layer 12 perpendicular to the stacking direction of the magnetoresistive effect element 102. Here, the upper electrode 1 shown in the magnetoresistive effect element 101 is not shown.

  Since the in-plane magnetic anisotropy is improved by increasing the cross section 14a of the bias magnetic field applying unit 14, and the holding force of the bias magnetic field applying unit 14 can be increased, the magnetoresistive effect element shown in the first embodiment is used. The magnetization direction of the magnetization fixed layer 12 in the case of the reflow process for mounting the element package including the magnetoresistive effect element 102 on the substrate, the self-heating inside the element, or the instantaneous temperature rise, as compared with the case of the shape of 101. Can be maintained by the bias magnetic field application unit 14.

  The rectangle circumscribing the cross section 14a of the bias magnetic field applying unit 14 has a side parallel to the magnetization direction of the cross section 14a of the bias magnetic field applying unit 14, and the length of the long side of the rectangle is the magnetoresistive effect element. 101 is longer than the longest diagonal line that can be taken in the cross section 12 c of the magnetization fixed layer 12, and the short side of the rectangle circumscribing the cross section 14 a of the bias magnetic field application unit 14 is parallel to the magnetization direction of the magnetization fixed layer 12. And longer than the short side of the rectangle circumscribing the cross section 12c.

  Desirably, the long side direction of the rectangle circumscribing the cross section 14a of the bias magnetic field application unit 14 is parallel to the magnetization direction of the magnetization fixed layer 12, that is, the magnetization direction of the bias magnetic field application unit 14 and the magnetization direction of the magnetization fixed layer 12 are In a parallel relationship, a cross section 14 a of the bias magnetic field application unit 14 having shape anisotropy in the long side direction of the rectangle circumscribing the bias magnetic field application unit 14 is set.

  By imparting shape anisotropy to the bias magnetic field application unit 14, it is possible to further enhance the effect of increasing the holding force by increasing the cross-sectional area of the bias magnetic field application unit 14.

  The shape of the cross section 14a of the bias magnetic field application unit 14 shown in the second embodiment can take any shape such as a polygon, an ellipse, a circle, and an indefinite shape.

(Third embodiment)
A configuration of a magnetoresistive element according to the third embodiment of the present invention will be described with reference to FIG.

  The magnetoresistive effect element 103 shown in the first embodiment has a structure in which the bias magnetic field applying unit 14 is formed of a laminated body having a ferromagnetic material like the magnetoresistive effect element 103 shown in FIG. 14 is different from the structure of the magnetoresistive effect elements 101 and 102 shown in the first embodiment and the second embodiment, and there are two bias magnetic field application portions made of a ferromagnetic film around the magnetization fixed layer 12. Arranged above.

  The bias magnetic field application unit 14 composed of a laminated body having a ferromagnetic material used in the first embodiment and the second embodiment has a direction perpendicular to the laminating direction of the magnetoresistive effect element, that is, a bias magnetic field. A magnetic field is generated from the end face of the application unit 14 and returns to the opposite end face. A magnetic field generated from the end face of the bias magnetic field application unit 14 is applied to the antiferromagnetic layer 13 to determine the magnetization direction. Since the magnetic field of the bias magnetic field application unit 14 is the strongest at the end surface than the in-plane part, the bias magnetic field application unit 14 and the antiferromagnetic layer 13 face each other as in the first and second embodiments. In the structure, the maximum magnetic field of the bias magnetic field applying unit 14 cannot be applied to the antiferromagnetic layer 13.

  Therefore, as shown in FIG. 4, the bias magnetic field applying unit 14 is divided into a plurality of parts, and the bias magnetic field applying unit 14 is arranged so that a magnetic field in one direction is applied to the antiferromagnetic layer 13. Since the magnetic field emitted from the end face of the magnetic field application unit 14 enters the end face of the other bias magnetic field application unit 14 and the antiferromagnetic layer 13 is disposed between them, the first embodiment and the second implementation are provided. It is possible to apply a stronger magnetic field than when the bias magnetic field applying unit 14 shown in the form applies a magnetic field to the antiferromagnetic layer 13.

  When the bias magnetic field applying unit 14 is divided into a plurality of parts, the bias magnetic field applying unit 14 has a magnetization free layer with respect to the plane 19 including the second surface 18 in which the magnetization fixed layer 12 faces the antiferromagnetic layer 13. 10 is located on the side opposite to the magnetization free layer 10, so that either the lower electrode 2 or the bias magnetic field application unit 14, which is a magnetic field application unit, is disposed on the surface of the antiferromagnetic layer 13 on the opposite side of the magnetization free layer 10. Is done.

  When the bias magnetic field application unit 14, which is a magnetic field application unit, is disposed on the surface of the antiferromagnetic layer 13 on the side opposite to the magnetization free layer 10, the bias magnetic field application unit 14 surrounds the antiferromagnetic layer 13. Since the magnetic field is less likely to leak outside the bias magnetic field application unit 14, an extra magnetic field other than the control magnetic field is not applied to the magnetization free layer 10. High frequency characteristics can be maximized.

(Fourth embodiment)
A configuration of a magnetoresistive effect element according to the fourth embodiment of the present invention will be described with reference to FIG.

  In order to use the magnetoresistive effect element shown in the first to third embodiments in an actual portable device or the like, as shown in FIG. 5, a semiconductor component or logic mounted according to the circuit pattern formed on the circuit board is used. The semiconductor circuit 38 needs to be combined with an IC, passive components, and the like.

  In order to produce the semiconductor circuit 38 shown in FIG. 5, the magnetoresistive effect element 36 is fixed on the lead frame 34 with silver paste, UV resin, thermosetting resin, or the like, and wire bonding or the like using a fine wire 35 of gold or aluminum. The circuit pattern on the substrate 30 made of glass epoxy or ceramic is obtained by sealing the element package 33 which is electrically connected to the lead frame and then sealed with an insulating resin material (not shown) such as a semiconductor sealing material. There is a mounting process in which the joint portion 31 and the solder 32 are joined, that is, a reflow process.

  In the reflow process, cream-like solder 32 is applied using a metal mask to the joint portion of the circuit pattern 31 on the substrate 30 shown in FIG. Heat is applied to the whole to melt the solder 32 and join the circuit pattern and components to produce the final form of the semiconductor circuit 38.

  As an example of the reflow method, after applying cream solder 32 to a part to be joined on the substrate 30 using a metal mask, the part such as the element package 33 is applied to the surface where the cream solder is applied with a chip mounter or the like. Implement. Thereafter, the substrate 30 is moved into the reflow furnace 37 by a belt conveyor in order to alleviate the sudden thermal shock to the component, and the substrate 30 on which the component is surface-mounted in the reflow furnace 37 is heated from 150 ° C. to 170 ° C. as a preheating process. Heat at about 0 ° C. and then perform the main heating. The solder 32 is melted by this heating, and the high temperature is maintained for a short time from 200 ° C. to 260 ° C. where the component terminals and the circuit pattern are joined for about 10 seconds. Although the melting temperature varies depending on the component composition of the solder 32, the lead-free solder needs to have a higher temperature. After the main heating, the substrate mounting is completed through a cooling process, and the semiconductor circuit 38 is completed.

  When the magnetoresistive effect element is mounted on the substrate, or when self-heating inside the element or an instantaneous temperature rise occurs, the magnetoresistive effect element is exposed to a temperature close to the temperature set during the annealing process. 12 may be reduced, and the magnetization direction fixed by the annealing process may change.

  However, the bias magnetic field applying unit 14 can always maintain a constant magnetization direction even when a reflow process or a temperature rise occurs, and the fixed magnetization direction changes due to a decrease in the coercive force of the magnetization fixed layer 12. However, the magnetization direction of the original magnetization fixed layer 12 can be maintained under the influence of the magnetic field direction of the bias magnetic field application unit 14.

  As a specific method for always maintaining a constant magnetization direction even when the bias magnetic field applying unit 14 undergoes a reflow process or a temperature rise, the film thickness is increased in order to increase the uniaxial anisotropy of the bias magnetic field applying unit 14. It is possible. Increasing the thickness of the bias magnetic field application unit 14 can increase the magnetic anisotropy in the bias magnetic field application unit 14.

  Further, when the bias magnetic field applying unit 14 is made of a ferromagnetic material, the temperature characteristic 20 of the bias magnetic field applying unit 14 in the relationship diagram between the temperature T and the magnetization amount H as shown in FIG. By using a material higher than the temperature characteristic 22, the magnetization amount Hm of the bias magnetic field application unit 14 can maintain more than half of the maximum magnetization amount Hmax at the temperature Tm at which the coercive force of the magnetization fixed layer 12 disappears in the reflow process. It is possible to maintain the magnetization direction of the magnetization fixed layer 12 by selecting a material that can be formed.

  By using the magnetoresistive effect element according to the present invention, it is possible to suppress deterioration of the high frequency characteristics of the magnetoresistive effect element even when the element is mounted on a substrate, or when self-heating inside the element or an instantaneous temperature rise occurs. It becomes possible to provide a possible element structure and a semiconductor circuit using the element structure.

101, 102, 103 ... magnetoresistive effect element 01 ... upper electrode 02 ... lower electrode 10 ... magnetization free layer 11 ... nonmagnetic spacer layer 12 ... magnetization fixed layer 12a ... 1st ferromagnetic layer 12b ... 2nd ferromagnetic layer 12c ... Cross section 13 of the magnetization fixed layer 12 ... Antiferromagnetic layer 14 ... Bias magnetic field application part 14a ... Bias magnetic field application part 14 cross section 15 ... insulating layer 16 ... magnetic field applying means 17 ... first surface 18 of the magnetization fixed layer 12 ... second surface 19 of the magnetization fixed layer 12 ... magnetization fixed layer 12 The flat surface 20 including the second surface 18 of the temperature characteristic of the bias magnetic field applying portion (ferromagnetic film) 23 the temperature at which the solder melts 30 the substrate 31 the circuit pattern 32 the solder 33 ・ ・ ・ Element package 34 Leadframe 35 ... wire 36 ... magnetoresistive element 37 ... flow reactor 38 ... semiconductor circuit

Claims (5)

A magnetization free layer whose magnetization direction changes according to an external magnetic field, a magnetization fixed layer whose magnetization direction is fixed, a nonmagnetic spacer layer disposed between the magnetization free layer and the magnetization fixed layer, A laminate having an antiferromagnetic layer, and a magnetic field applying means for applying a magnetic field to the magnetization free layer;
A magnetoresistive effect element including a bias magnetic field application unit that applies a bias magnetic field to the magnetization fixed layer in which the magnetization direction is fixed,
The magnetization fixed layer has a first surface facing the nonmagnetic spacer layer, and a second surface opposite to the first surface,
The laminated body having the antiferromagnetic layer is opposed to the second surface of the magnetization fixed layer,
The magnetoresistive device characterized in that the entire bias magnetic field applying unit is on the opposite side of the magnetization free layer with respect to a plane including the second surface of the magnetization fixed layer, and the bias magnetic field applying unit is a ferromagnetic material. Effect element.   The minimum value of the cross-sectional area of the bias magnetic field applying section perpendicular to the stacking direction of the magnetoresistive effect element is a cross section of the magnetization fixed layer perpendicular to the stacking direction of the magnetoresistive effect element. The magnetoresistive effect element according to claim 1, wherein the magnetoresistive effect element is larger than a minimum value of the area.   The magnetoresistive effect element according to claim 1, wherein the bias magnetic field application unit has shape anisotropy in a direction parallel to a magnetization direction of the magnetization fixed layer.   The magnetoresistive effect element according to claim 1, wherein the bias magnetic field applying unit includes a plurality of regions. An element package including the magnetoresistive effect element according to claim 1, a board, and solder for joining the element package and the board,
The semiconductor circuit according to claim 1, wherein a coercive force of the bias magnetic field application unit of the magnetoresistive effect element retains at least half of a maximum magnetization of the bias magnetic field application unit at a temperature at which the solder melts.

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