JP2008147488A - Magnetoresistance effect element, and mram - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce an area of a magnetoresistance effect element based on a magnetic wall movement method. <P>SOLUTION: The magnetoresistance effect element includes at least two first magnetization fixed layers 1a, 1b whose direction of magnetization is fixed, a magnetization free layer 2 whose direction of magnetization formed on a XY plane is variable, and a second magnetization fixed layer 4 which is connected to the magnetization free layer 2 through a non-magnetic layer 3. The two first magnetization fixed layers 1a, 1b are located opposite to the second magnetization fixed layer 4 sandwiching the magnetization free layer 2 and are magnetically joined with the magnetization free layer 2. Both the first magnetization fixed layers 1a, 1b have a component of the Z direction orthogonal to the XY plane. When data-writing, the writing current flows from one end of the magnetization free layer 2 to the other end in the XY plane. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a magnetoresistive effect element and a magnetic random access memory (MRAM) using the magnetoresistive effect element as a memory cell. In particular, the present invention relates to an MRAM based on a domain wall motion method and a magnetoresistive effect element used in the MRAM.

  MRAM is a promising nonvolatile memory from the viewpoint of high integration and high-speed operation. In the MRAM, a “magnetoresistance effect element” showing a magnetoresistance effect such as a TMR (Tunnel MagnetoResistance) effect is used as a memory cell. In the magnetoresistive effect element, for example, a magnetic tunnel junction (MTJ: Magnetic Tunnel Junction) in which a tunnel barrier layer is sandwiched between two ferromagnetic layers is formed. The two ferromagnetic layers are composed of a magnetization pinned layer (pinned layer) whose magnetization direction is fixed and a magnetization free layer (free layer) whose magnetization direction can be reversed. .

  The resistance value (R + ΔR) of the MTJ when the magnetization direction of the magnetization fixed layer and the magnetization free layer is “antiparallel” is larger than the resistance value (R) when they are “parallel” due to the magnetoresistance effect. It is known to grow. The MR ratio (= ΔR / R) at room temperature is several 10 to several 100%. The memory cell of the MRAM stores data in a nonvolatile manner by utilizing the change in resistance value. Data is read by passing a read current through the MTJ and measuring the resistance value of the MTJ. On the other hand, data is written by reversing the magnetization direction of the magnetization free layer.

  As a typical data writing method, a “current magnetic field method” is known. According to the current magnetic field method, a write current is caused to flow through the write wiring arranged in the vicinity of the magnetoresistive effect element. A write magnetic field generated by the write current is applied to the magnetization free layer, thereby changing the magnetization direction of the magnetization free layer. At this time, the magnetic field generated by the write current of 1 mA is about several Oe to several tens Oe. On the other hand, in order to prevent rewriting of stored data due to thermal disturbance (disturbance), it is desirable that the reversal magnetic field necessary for the magnetization reversal of the magnetization free layer is designed to be about several tens Oe. Therefore, it is very difficult to realize data writing with a write current of 1 mA or less. In this respect, the current magnetic field type MRAM is disadvantageous than other RAMs. Furthermore, the reversal magnetic field required for the magnetization reversal of the magnetization free layer becomes substantially inversely proportional to the size of the magnetoresistive effect element. That is, there is a problem that the write current increases as the memory cell is miniaturized.

  Patent Document 1 (Japanese Patent Laid-Open No. 2005-150303) describes a technique for improving the resistance to thermal disturbance and reducing the reversal magnetic field in the current magnetic field type MRAM. The magnetoresistive effect element according to the prior art has a ferromagnetic tunnel junction including a three-layer structure of a first ferromagnetic layer / tunnel barrier layer / second ferromagnetic layer. The first ferromagnetic layer has a larger coercive force than the second ferromagnetic layer. Further, the magnetization of the end portion of the second ferromagnetic layer is fixed in a direction having a component orthogonal to the magnetization easy axis direction of the second ferromagnetic layer.

  Recently, a “spin injection method” using spin transfer has been proposed as a data writing method instead of the current magnetic field method (see, for example, Non-Patent Document 1 and Patent Document 2). According to the spin injection method, a spin-polarized current is injected into the magnetization free layer, and the magnetization is reversed by a direct interaction between the spin of the conduction electron carrying the current and the magnetic moment of the conductor. . Since the magnetization reversal is more likely to occur as the current density increases, the write current can be reduced as the memory cell size is reduced.

  According to the spin injection method described in Non-Patent Document 1 (M. Hosomi et al.), A write current is passed through the MTJ. That is, the spin injection method according to the related art is realized by a so-called CPP (Current Perpendicular to Plane) method, and is hereinafter referred to as a “vertical spin injection method”. In the vertical spin injection method, spin-polarized electrons having the same spin state as the magnetization fixed layer are supplied from the magnetization fixed layer to the magnetization free layer, or are extracted from the magnetization free layer to the magnetization fixed layer. As a result, the magnetization of the magnetization free layer is reversed by the spin transfer effect. Thus, the magnetization direction of the magnetization free layer can be defined by the direction of the write current passing through the MTJ. Further, the write current can be reduced with the miniaturization of the memory cell.

  However, in the vertical spin injection method, since a write current larger than the read current penetrates the MTJ, it is considered that the following problem occurs. An insulating film is generally used as the MTJ tunnel barrier layer, and the upper limit value of the write current is determined from the limit of the withstand voltage of the insulating film. This is not preferable from the viewpoint of writing. On the other hand, if the resistance value of the tunnel barrier layer is lowered in order to increase the upper limit value, the read signal becomes small. This is not preferable from the viewpoint of reading. That is, writing must be performed within a margin that is greater than the current at which magnetization reversal occurs and less than the withstand voltage of the insulating film that satisfies the read constraint, which is disadvantageous for increasing the capacity. Furthermore, it is not preferable from the viewpoint of the durability of the device to cause a write current to flow through the insulating film every time a write operation is performed.

  On the other hand, according to the spin injection method described in Patent Document 2 (Japanese Patent Laid-Open No. 2005-191032), the write current does not penetrate the MTJ and flows in a plane in the magnetization free layer. Such a spin injection method is hereinafter referred to as a “horizontal spin injection method”. More specifically, the magnetization free layer according to the related art has a junction overlapping the tunnel barrier layer, a constriction adjacent to both ends of the junction, and a pair of magnetization fixed portions formed adjacent to the constriction. The pair of magnetization fixed portions are provided with fixed magnetizations in opposite directions. As a result, the magnetization free layer has a domain wall in the junction.

  A write current flows in a plane in the magnetization free layer configured as described above. At this time, the pair of magnetization fixed portions serves as a supply source of different spin-polarized electrons. The direction of the write current is controlled according to the write data, and spin-polarized electrons are supplied from one of the magnetization fixed portions to the junction according to the direction. As a result, the magnetization of the magnetization free layer is reversed by the spin transfer effect. This magnetization reversal means the change of the position of the above-mentioned domain wall. That is, the domain wall moves between the pair of constricted portions according to the direction of the write current. In that sense, the horizontal spin injection method described in Patent Document 2 can also be referred to as a “domain wall motion method”.

  Such current-driven domain wall motion is actually observed in a ferromagnetic thin wire (see Non-Patent Document 2). When a current that crosses the domain wall flows through a magnetic wire having a domain wall with a width of several tens of nanometers to several micrometers, the domain wall is moved by the spin magnetic moment of the conduction electrons. The current value required for the domain wall movement also decreases with the miniaturization of the element. Therefore, the horizontal spin injection method (domain wall motion method) using domain wall motion is a very important technique for realizing a large capacity and low current operation MRAM.

JP 2005-150303 A JP 2005-191032 A M. Hosomi et al., "A Novel Nonvolatile Memory with Spin Torque Transfer Magnetization Switching: Spin-RAM", International Electron Devices Meeting (IEDM), Technical Digest, pp.459-562, 2005. Yamaguchi et. Al., "Real-Space Observation of Current-Driven Domain Wall Motion in Submicron Magnetic Wires", PRL, vol. 92, pp. 077205-1, 2004.

  The inventor of the present application paid attention to the following points. According to the technique described in Patent Document 2, the magnetization free layer has a pair of magnetization fixed portions on both sides of the junction portion in which the magnetization direction is variable. The pair of magnetization fixed portions are introduction sources of different spin-polarized electrons, and are provided with fixed magnetizations in opposite directions. And these junction part and a pair of magnetization fixed part are arrange | positioned linearly in the same magnetic layer. Providing a pair of magnetization fixed portions in addition to a region having a variable magnetization direction in the same magnetic layer causes the following problems.

  First, in the same magnetic layer, it is necessary to fix the magnetizations of the pair of magnetization fixed portions in opposite directions. This requires a complicated manufacturing process. Further, the required magnetic characteristics are different between a region in which the magnetization direction is variable and a region in which the magnetization direction is fixed. However, when these regions exist in the same magnetic layer, it is difficult to adjust the magnetic characteristics for each region. That is, the degree of freedom in design is poor. Furthermore, in order to stably maintain the fixed magnetization of the magnetization fixed part, it is necessary to design the magnetization fixed part to be somewhat large. This leads to an increase in the area of the memory cell.

  An object of the present invention is to provide a new magnetoresistive element and MRAM based on a domain wall motion method.

  Another object of the present invention is to provide a technique capable of improving the degree of freedom in designing a magnetoresistive effect element.

  Still another object of the present invention is to provide a technique capable of reducing the area of a magnetoresistive effect element and realizing a large-capacity MRAM.

  Still another object of the present invention is to provide a magnetoresistive effect element and an MRAM that can easily fix the magnetization direction of a magnetization fixed layer.

  [Means for Solving the Problems] will be described below using the numbers and symbols used in [Best Mode for Carrying Out the Invention]. These numbers and symbols are added in parentheses in order to clarify the correspondence between the description of [Claims] and [Best Mode for Carrying Out the Invention]. However, these numbers and symbols should not be used for the interpretation of the technical scope of the invention described in [Claims].

  In a first aspect of the present invention, a magnetoresistive effect element based on a domain wall motion system is provided. The magnetoresistive element includes at least two first magnetization fixed layers (1a, 1b) whose magnetization directions are fixed, and a magnetization free layer (2) formed on the first plane (XY) and having a variable magnetization direction. ) And a second magnetization fixed layer (4) connected to the magnetization free layer (2) through the nonmagnetic layer (3). The two first magnetization fixed layers (1a, 1b) are arranged so as to face the second magnetization fixed layer (4) with the magnetization free layer (2) interposed therebetween, and are magnetically coupled to the magnetization free layer (2). Is bound to. The magnetizations of the two first magnetization fixed layers (1a, 1b) both have a component in the first direction (Z) perpendicular to the first plane (XY). At the time of data writing, a write current flows from one end of the magnetization free layer (2) to the other end in the first plane (XY).

  In a second aspect of the present invention, an MRAM (100) based on a domain wall motion method is provided. The MRAM (100) includes a plurality of magnetic memory cells (110) arranged in an array. Each of the plurality of magnetic memory cells (110) includes the magnetoresistive effect element and transistors (10a, 10b) for supplying a write current to the magnetization free layer (2) when data is written.

  According to the present invention, the first magnetization fixed layer and the magnetization free layer are not formed on the same plane but are arranged three-dimensionally. As a result, the degree of freedom in designing the magnetoresistive element is improved. In addition, the area of the magnetoresistive effect element is reduced. Furthermore, the magnetization direction of the first magnetization fixed layer can be easily fixed.

  A magnetoresistive effect element and an MRAM according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

1. 1. First embodiment 1-1. Basic Structure FIGS. 1A and 1B are a side view and a plan view schematically showing the structure of the magnetoresistive effect element according to the first embodiment. The magnetoresistive effect element includes first magnetization fixed layers 1 a and 1 b, a magnetization free layer 2, a tunnel barrier layer 3, and a second magnetization fixed layer 4. The magnetization free layer 2, the tunnel barrier layer 3, and the second magnetization fixed layer 4 are laminated in order. In FIGS. 1A and 1B, the stacking direction is defined as the “Z direction”. That is, the direction perpendicular to the main surface of each layer is the Z direction. Each layer is formed on an XY plane perpendicular to the Z direction.

  The magnetization free layer (free layer) 2 includes a ferromagnetic layer, and its magnetization direction is variable. As shown in FIG. 1B, the magnetization free layer 2 is formed on the XY plane, and its longitudinal direction is the X direction. That is, the magnetization easy axis of the magnetization free layer 2 coincides with the X direction, and the magnetization of the magnetization free layer 2 is allowed to be in the + X direction or the −X direction.

  The tunnel barrier layer 3 is a nonmagnetic layer. For example, the tunnel barrier layer 3 is formed of an insulating film. The tunnel barrier layer 3 is sandwiched between the magnetization free layer 2 and the second magnetization fixed layer 4. In FIG. 1B, the tunnel barrier layer 3 has the same width as the magnetization free layer 2, but may have the same width as the second magnetization fixed layer 4. Alternatively, the width of the tunnel barrier layer 3 may change midway from the same width as the second magnetization fixed layer 4 to the same width as the magnetization free layer 2.

  The second magnetization fixed layer (pinned layer) 4 includes a ferromagnetic layer in contact with the tunnel barrier layer 3, and the magnetization direction is fixed in one direction in the plane by an antiferromagnetic layer (not shown). Yes. For example, in FIG. 1A, the magnetization direction of the second magnetization fixed layer 4 in contact with the tunnel barrier layer 3 is fixed in the + X direction. The second magnetization fixed layer 4 may have a laminated structure in which a plurality of ferromagnetic layers are magnetically coupled via a nonmagnetic layer. In that case, for example, adjacent ferromagnetic layers are antiferromagnetically coupled via a nonmagnetic layer. Thereby, the leakage magnetic field from the second magnetization fixed layer 4 is reduced, and the fixed magnetization is further strengthened.

  Thus, the magnetization free layer 2 and the second magnetization fixed layer 4 are connected via the tunnel barrier layer 3. The MTJ is formed by the magnetization free layer 2, the tunnel barrier layer 3, and the second magnetization fixed layer 4.

  Further, the magnetoresistive effect element according to the present embodiment includes first magnetization fixed layers 1a and 1b separately from the second magnetization fixed layer 4 constituting the MTJ. The first magnetization fixed layers 1a and 1b are disposed so as to face the second magnetization fixed layer 4 with the magnetization free layer 2 interposed therebetween. More specifically, as shown in FIG. 1B, the first magnetization fixed layer 1 a is disposed on one end side of the magnetization free layer 2, and the first magnetization fixed layer 1 b is on the other end side of the magnetization free layer 2. Is arranged. In particular, according to the present embodiment, as shown in FIG. 1A, the first magnetization fixed layer 1 a is connected to one end of the magnetization free layer 2, and the first magnetization fixed layer 1 b Connected to the end. The longitudinal direction (easy magnetization axis) of the first magnetization fixed layers 1a and 1b is the Z direction perpendicular to the XY plane, and they have shape magnetic anisotropy in the Z direction.

  The first magnetization fixed layers 1 a and 1 b are ferromagnetic layers and are magnetically coupled to the magnetization free layer 2. The magnetization directions of the first magnetization fixed layers 1a and 1b are fixed in one direction. Specifically, the first magnetization fixed layers 1a and 1b are formed such that the fixed magnetization has at least a component in the Z direction. For example, as shown in FIG. 1A, the magnetization directions of the first magnetization fixed layers 1a and 1b are fixed to the same + Z direction. Alternatively, the magnetization directions of the first magnetization fixed layers 1a and 1b may be fixed in the same −Z direction. That is, the magnetizations of the first magnetization fixed layers 1 a and 1 b are both fixed in the direction toward the magnetization free layer 2 or in the direction away from the magnetization free layer 2. The magnetization is fixed by shape magnetic anisotropy, crystal magnetic anisotropy, pinning layer arrangement, and the like. The fixed magnetization of the first magnetization fixed layers 1 a and 1 b magnetically affects the magnetization around the end of the magnetization free layer 2.

1-2. Principle of Operation FIG. 2 shows two types of magnetization states that the magnetization free layer 2 according to the present embodiment can take. When the magnetization direction of the magnetization free layer 2 is the -X direction, that is, when the direction is antiparallel to the magnetization direction (+ X direction) of the second magnetization fixed layer 4, the MTJ resistance value is relatively large. . This antiparallel state is associated with, for example, data “1”. On the other hand, when the magnetization direction of the magnetization free layer 2 is the + X direction, that is, when the direction is parallel to the magnetization direction (+ X direction) of the second magnetization fixed layer 4, the resistance value of the MTJ is relatively small. . This parallel state is associated with, for example, data “0”.

  In the case of data “1”, the magnetization (−X direction) of the magnetization free layer 2 is continuously connected from the first magnetization fixed layer 1b. Since the magnetization of the other first magnetization fixed layer 1a is fixed in the direction toward the magnetization free layer 2, as shown in FIG. 2, the domain wall DW is in the magnetization free layer 2 in the vicinity of the first magnetization fixed layer 1a. Will exist. On the other hand, in the case of data “0”, the magnetization (+ X direction) of the magnetization free layer 2 is continuously connected from the first magnetization fixed layer 1a. Since the magnetization of the other first magnetization fixed layer 1b is fixed in the direction toward the magnetization free layer 2, as shown in FIG. 2, the domain wall DW is in the magnetization free layer 2 near the first magnetization fixed layer 1b. Will exist. As described above, the domain wall DW is introduced into the magnetization free layer 2 by providing the first magnetization fixed layers 1 a and 1 b. The data “1” and “0” can be distinguished by the position of the domain wall DW. Note that these two states are equivalent in terms of energy.

  FIG. 3 shows a magnetic moment distribution in the vicinity of the connection region between the first magnetization fixed layer 1a and the magnetization free layer 2. As shown in FIG. As described above, the domain wall DW exists in the magnetization free layer 2 in the vicinity of the first magnetization fixed layer 1a. Although a head-to-head type domain wall DW is shown as an example, the domain wall DW may be a tail-to-tail type. Further, although the Transverse type in which the magnetic moment in the domain wall DW has a Z-axis component is shown, the magnetic moment in the domain wall DW may have a Y-axis component. Alternatively, a Voltex-type domain wall may be formed instead of the Transverse-type domain wall.

  As shown in FIG. 3, the magnetization of the first magnetization fixed layer 1a affects the magnetization of the end portion of the magnetization free layer 2, and the magnetization of the end portion of the magnetization free layer 2 is generally directed in the + Z direction. ing. At this time, the dipole magnetic field BT generated by the fixed magnetization of the first magnetization fixed layer 1a is distributed as shown by the broken line in FIG. Therefore, the magnetization MA of the end portion of the first magnetization fixed layer 1a and the magnetization MB of the magnetization free layer 2 immediately above it have a component in the + X direction. Conversely, the magnetization MC at the extreme end of the magnetization free layer 2 has a component in the −X direction. The directions of these magnetizations MA, MB, and MC are affected by the shapes, magnitude relationships, positional relationships, and the like of the first magnetization fixed layer 1a and the magnetization free layer 2, but the basic tendency is the same.

  As described above, the magnetization of the first magnetization fixed layer 1a gives at least the magnetic force in the + X direction to the magnetization of one end of the magnetization free layer 2, and as a result, magnetizations MA and MB having a component in the + X direction are generated. As will be described later, these magnetizations MA and MB play an important role in supplying electrons having a magnetic moment in the + X direction (+ X direction spin-polarized electrons). The same argument can be applied to the other first magnetization fixed layer 1b. As a result of the magnetization of the first magnetization fixed layer 1b giving at least a magnetic force in the −X direction to the magnetization of the other end of the magnetization free layer 2, magnetization having a −X direction component is generated. As will be described later, such magnetization plays an important role in supplying electrons having a magnetic moment in the −X direction (−X direction spin-polarized electrons).

  Data is written by the “horizontal spin injection method”. That is, the write current does not pass through the MTJ and flows in a plane in the magnetization free layer 2. Specifically, it flows from one end of the magnetization free layer 2 to the other end.

  For example, when the data “1” is rewritten to “0”, the write current flows from the first magnetization fixed layer 1 b to the first magnetization fixed layer 1 a through the magnetization free layer 2. In this case, as shown in FIG. 2, electrons flow from the first magnetization fixed layer 1a through the magnetization free layer 2 to the first magnetization fixed layer 1b. At this time, the spin polarization of electrons in the + X direction is increased by the magnetizations MA and MB shown in FIG. That is, + X direction spin-polarized electrons are efficiently generated by the magnetizations MA and MB. Since the + X direction spin-polarized electrons flow into the magnetization free layer 2, the magnetization of the magnetization free layer 2 is reversed in the + X direction by the spin transfer effect. As shown in FIG. 3, the magnetization MC having a component in the −X direction exists at the outermost end portion of the magnetization free layer 2. However, since the write current hardly flows in the magnetization MC region, the influence of the magnetization MC hardly appears.

  On the other hand, when the data “0” is rewritten to “1”, the write current flows from the first magnetization fixed layer 1a through the magnetization free layer 2 to the first magnetization fixed layer 1b. Accordingly, as shown in FIG. 2, electrons flow from the first magnetization fixed layer 1b to the first magnetization fixed layer 1a through the magnetization free layer 2. In this case as well, −X direction spin-polarized electrons are efficiently generated by the magnetization in the vicinity of the end of the first magnetization fixed layer 1b. Since the −X direction spin-polarized electrons flow into the magnetization free layer 2, the magnetization of the magnetization free layer 2 is reversed in the −X direction by the spin transfer effect. In this way, data writing can be realized by controlling the direction of the write current flowing in the magnetization free layer 2.

  Data writing can also be described from the viewpoint of domain wall motion. When the data “1” is rewritten from “0”, the + X direction spin-polarized electrons give the + X direction spin torque to the domain wall DW. As a result, the domain wall DW moves in the + X direction from the first magnetization fixed layer 1a side. The domain wall motion is stopped by the magnetization in the + Z direction by the other first magnetization fixed layer 1b. On the other hand, when the data “0” is rewritten from “1”, the −X direction spin-polarized electrons give the −X direction spin torque to the domain wall DW. As a result, the domain wall DW moves in the −X direction from the first magnetization fixed layer 1b side. The domain wall movement is stopped by the magnetization in the + Z direction by the other first magnetization fixed layer 1a (see FIG. 3). In the present embodiment, it can be said that data writing is realized by the “domain wall motion method”.

  The characteristics of domain wall motion are determined by the materials and shapes of the first magnetization fixed layers 1 a and 1 b and the magnetization free layer 2. As will be described later, the domain wall motion characteristics can be improved by appropriately adjusting the magnetic characteristics, shape, magnitude relationship, and positional relationship of the materials with respect to the first magnetization fixed layers 1a, 1b and the magnetization free layer 2. it can.

  Data is read by detecting the resistance value of the MTJ. Specifically, a read current is passed between the magnetization free layer 2 and the second magnetization fixed layer 4 so as to penetrate the MTJ. Based on the read current, the resistance value of MTJ is detected, and data “1” or “0” is sensed.

1-3. Various Planar Shapes FIG. 4 shows various XY planar shapes (cut planes) of the first magnetization fixed layer 1 (1a, 1b). Examples of the planar shape of the first magnetization fixed layer 1 include a circle, an ellipse, a quadrangle, and a polygon. The type and position of the domain wall formed in the magnetization free layer 2 can be controlled by the type of the planar shape.

  FIG. 5A shows various XY plane shapes of the magnetization free layer 2. The aspect ratio (major axis / minor axis) of the planar shape of the magnetization free layer 2 is larger than 1. Examples of the planar shape include an ellipse, a rectangle, and a polygon.

  5B and 5C show various modifications of the magnetization free layer 2. In any of the modifications, the magnetization free layer 2 includes a first region B1 located on one end side with respect to the central portion and a second region B2 located on the other end side with respect to the central portion. The cross-sectional areas of the first region B1 and the second region B2 are different from the cross-sectional area of the central portion. From the viewpoint of energy, the domain wall DW becomes more stable as its area decreases. In the example shown in FIG. 5B, the central portion is thicker than the first region B1 and the second region B2. In this case, the domain wall DW is prevented from stopping near the center. In the example shown in FIG. 5C, concave portions or convex portions are formed on the side portions of the first region B1 and the second region B2. In the case of the concave portion, the cross-sectional area of the first region B1 and the second region B2 is smaller than the cross-sectional area of the central portion. As a result, the domain wall DW tends to stop in the first region B1 or the second region B2 during data writing. In the case of a convex part, the cross-sectional area of 1st area | region B1 and 2nd area | region B2 is larger than the cross-sectional area of a center part. As a result, at the time of data writing, the domain wall DW tends to stop before the first region B1 or the second region B2. Thus, by providing the first region B1 and the second region B2 in the magnetization free layer 2, the operating characteristics are improved.

1-4. Various Planar Positional Relationships FIGS. 6A to 6C show various positional relationships between the first magnetization fixed layer 1 (1a, 1b) and the magnetization free layer 2. FIG. The positional relationship is a planar positional relationship when viewed from the Z direction.

  As shown in FIG. 6A, the two first magnetization fixed layers 1 are provided at both ends of the magnetization free layer 2. The two first magnetization fixed layers 1 may be located slightly inside the both ends, or may be located slightly outside the both ends. In particular, it is preferable that the two first magnetization fixed layers 1 are located slightly outside from both ends. More specifically, the planar shape of one first magnetization fixed layer 1a protrudes in the −X direction from the planar shape of the magnetization free layer 2, and the planar shape of the other first magnetization fixed layer 1b is the magnetization free layer. 2 protrudes in the + X direction from the planar shape. As a result, as shown in FIG. 6A, the protruding portion Pb appears. In this case, the magnetization MC having the component in the −X direction shown in FIG. At the same time, the contribution of the magnetization MB having a component in the + X direction is relatively large, which is preferable. That is, the supply efficiency of + X direction spin-polarized electrons can be increased, and the domain wall DW can be stably stopped at an appropriate position.

  As shown in FIG. 6B, the width of the first magnetization fixed layer 1 in the Y direction may be larger or smaller than the width of the magnetization free layer 2 in the Y direction. However, from the viewpoint of the above-described protrusion Pb, it is preferable that the width of the first magnetization fixed layer 1 in the Y direction is larger than the width of the magnetization free layer 2 in the Y direction. Further, as shown in FIG. 6C, three or more first magnetization fixed layers 1 may be provided. In that case, at least one first magnetization fixed layer 1 is provided in the vicinity of one end of the magnetization free layer 2. In the case of the example shown in FIG. 6C, the four first magnetization fixed layers 1 are preferably provided so that the protruding portions Pb appear at the four corners of the magnetization free layer 2, respectively.

1-5. Various Side Shapes FIGS. 7A to 7D show various side shapes of the magnetoresistive effect element according to the present embodiment. In the example shown in FIG. 7A, the magnetization free layer 2 and the tunnel insulating layer 3 have a tapered structure that expands toward the first magnetization fixed layer 1. That is, the side surface ST of the magnetization free layer 2 and the tunnel insulating layer 3 is processed into a taper shape. The taper processing is performed by controlling etching conditions and milling conditions. Referring to FIG. 3 described above, it can be seen that when the side surface ST of the magnetization free layer 2 is tapered, the magnetization at the end of the magnetization free layer 2 is easily oriented in the + X direction. That is, the taper structure increases the magnetization component in the + X direction in the magnetization free layer 2. As a result, the supply efficiency of the + X direction spin-polarized electrons increases, so that the write current required for the domain wall movement can be reduced.

  In the example shown in FIGS. 7B and 7C, the first magnetization fixed layers 1a and 1b have a tapered structure that expands as the magnetization free layer 2 is approached. That is, the side surfaces ST of the first magnetization fixed layers 1a and 1b are processed into a taper shape. In this case, the magnetization component in the + X direction in the first magnetization fixed layer 1 and the magnetization free layer 2 increases. As a result, the supply efficiency of the + X direction spin-polarized electrons increases, so that the write current required for the domain wall movement can be reduced.

  Furthermore, in the example shown in FIG. 7D, the longitudinal direction of the first magnetization fixed layers 1a and 1b is oblique to the XY plane. That is, the easy magnetization axes of the first magnetization fixed layers 1a and 1b are deviated from the Z axis. The fixed magnetization of the first magnetization fixed layer 1a has a component in the + X direction, and the fixed magnetization of the first magnetization fixed layer 1b has a component in the -X direction. As a result, the supply efficiency of spin-polarized electrons suitable for domain wall movement is remarkably increased, which is preferable.

1-6. Material As the material of the first magnetization fixed layer 1, the magnetization free layer 2, and the second magnetization fixed layer 4, for example, Fe (iron), Co (cobalt), Ni (nickel), or an alloy containing them as a main component is used. be able to. In particular, Fe—Ni, Fe—Co—Ni, and Fe—Co are desirable. Moreover, you may adjust characteristics, such as a magnetic characteristic, crystallinity, a mechanical characteristic, and a chemical characteristic, by adding a nonmagnetic element to these magnetic bodies. Nonmagnetic elements to be added include Ag (silver), Cu (copper), Au (gold), B (boron), C (carbon), N (nitrogen), O (oxygen), Mg (magnesium), Al (Aluminum), Si (silicon), P (phosphorus), Ti (titanium), Cr (chromium), Zr (zirconium), Nb (niobium), Mo (molybdenum), Hf (hafnium), Ta (tantalum), W (Tungsten), Pd (palladium), Pt (platinum) and the like. In that case, materials such as Ni—Fe—Zr and Co—Fe—B are exemplified.

  The magnetization free layer 2 is a layer in which the domain wall moves, and preferably has a crystal structure capable of realizing smooth domain wall movement. Lattice defects, grain boundaries, and the like serve as pinning sites that hinder smooth domain wall movement. Therefore, it is desirable that the magnetization free layer 2 has a structure that does not include many pinning sites, such as an amorphous structure or a single crystal structure. For the amorphous structure, P, Si, B, C, or the like is added to the magnetic material, the film is formed in a nitrogen atmosphere, the film formation rate is controlled, or the film is formed by cooling the substrate. Can be realized. In addition, it is possible to increase the single crystallinity by heating the substrate to form a film or by appropriately selecting a seed layer for crystal growth. In addition, by controlling the magnetic anisotropy in the vertical direction, the ease of orientation of the magnetic moment in the domain wall DW in the Z direction can be adjusted.

  For the second magnetization fixed layer 4, it is desirable to use a material having a large coercive force in order to prevent magnetization reversal. In order to obtain a wide operation margin and a high signal-to-noise ratio (SN ratio) during a read operation, it is desirable to select a magnetic material that can provide a high MR ratio. Specifically, Fe, Co, Ni, or an alloy made of them may be selected as the material for the second magnetization fixed layer 4. By adding a 4d, 5d transition metal element, a rare earth element, or the like to such a magnetic material, the magnetic characteristics can be adjusted.

  Regarding the first magnetization fixed layer 1, it is desirable that magnetization reversal hardly occurs and that the domain wall hardly move. Therefore, it is desirable to use a material having a large coercive force as the material of the first magnetization fixed layer 1. Moreover, it is desirable that the first magnetization fixed layer 1 has a structure including many lattice defects and grain boundaries. Furthermore, in order to move the domain wall DW with a low current, it is desirable that the spin polarization rate of conduction electrons during writing is high. For this purpose, the material of the first magnetization fixed layer 1 and the magnetization free layer 2 is desirably a material having a high spin polarizability.

As a material of the tunnel barrier layer 3, an insulator such as Al ₂ O ₃ (aluminum oxide), SiO ₂ (silicon oxide), MgO (magnesium oxide), AlN (aluminum nitride), or the like can be used. Further, as the material of the tunnel barrier layer 3, a nonmagnetic metal such as Cu, Cr, Al, Zn (zinc) can be used.

1-7. Circuit Configuration FIG. 8 is a circuit diagram showing an example of a magnetic memory cell using the magnetoresistive element described above. In FIG. 8, select transistors 10a and 10b for supplying a write current are connected to the first magnetization fixed layers 1a and 1b. Specifically, one of the source / drain of the selection transistor 10a is connected to the first magnetization fixed layer 1a, and the other is connected to the first bit line 11a. Similarly, one of the source / drain of the selection transistor 10b is connected to the first magnetization fixed layer 1b, and the other is connected to the second bit line 11b. The gates of the selection transistors 10 a and 10 b are connected to the word line 12. Further, the second magnetization fixed layer 4 is connected to the ground wire 13.

  When writing data, the word line 12 is turned on, the ground line 13 is turned off, and a predetermined potential difference is applied between the bit lines 11a and 11b. As a result, the write current is, for example, a path of “first bit line 11a—selection transistor 10a—first magnetization fixed layer 1a—magnetization free layer 2—first magnetization fixed layer 1b—selection transistor 10b—second bit line 11b”. Flowing. A reverse current path is also possible. Thereby, the data writing shown in the foregoing embodiments is realized.

  When reading data, the word line 12 is turned on, the ground line 13 is turned on, and the bit lines 11a and 11b are set to the same potential. As a result, the read current is “bit lines 11a, 11b—selection transistors 10a, 10b—first magnetization fixed layer 1a, 1b—magnetization free layer 2—tunnel barrier layer 3—second magnetization fixed layer 4—ground line 13”. Flowing through the path. Based on the read current, stored data can be sensed.

  FIG. 9 shows an example of the configuration of the MRAM 100 in which a plurality of magnetic memory cells 110 are arranged in an array. Each magnetic memory cell 110 has the configuration shown in FIG. The word line 12 is connected to the X selector 120, and the X selector 120 selects the word line 12 connected to the magnetic memory cell 110 to be accessed. The bit lines 11a and 11b are connected to the Y selector 130 and the Y-side current termination circuit 140. The Y selector 130 selects the bit line 11a (or 11b) connected to the magnetic memory cell 110 to be accessed. A write current is supplied to or extracted from the magnetic memory cell 110 to be accessed through the selected bit line.

1-8. Layout FIG. 10 shows an example of a cross-sectional structure of the magnetic memory cell shown in FIG. 11A to 11E show XY plane layout examples for the layers LA to LE in FIG. Conversely, a cross-sectional structure taken along line AA ′ in FIGS. 11A to 11E is shown in FIG.

  Referring to FIG. 10, element isolation structure 17 is formed in semiconductor substrate 16. Select transistors 10a and 10b are formed in the element regions on both sides of the element isolation structure 17, respectively. Each selection transistor has a gate electrode (word line) 12 formed on a semiconductor substrate 16 via a gate insulating film, and diffusion layers (source / drain) 18a and 18b formed on the surface of the semiconductor substrate 16. ing. The diffusion layer 18 a is connected to the first magnetization fixed layers 1 a and 1 b through the via 15, the metal layer 14, and the electrode layer 19. On the other hand, the diffusion layer 18b is connected to the bit lines 11a and 11b through the via 15 and the metal layer 14 in the uppermost layer. The second magnetization fixed layer 4 is connected to the ground wire 13 through the electrode layer 19 and the via 15.

  As shown in FIGS. 11A to 11E, the structures shown in FIG. 10 are laid out without waste. The write method according to the present embodiment in which the write current is supplied to the magnetization free layer 2 using the selection transistor 10 does not require a write wiring required for the current magnetic field method. In addition, the writing method can effectively use a transistor provided over a semiconductor substrate without waste. Further, as shown in FIG. 11A, the gate electrodes (word lines) 12 of the select transistors 10a and 10b are shared.

Furthermore, according to the present embodiment, the first magnetization fixed layers 1a and 1b and the magnetization free layer 2 are not formed on the same plane, but are sterically combined. In order to stably maintain the fixed magnetization of the first magnetization fixed layers 1a and 1b, a certain amount of volume is required as the first magnetization fixed layers 1a and 1b. According to the present embodiment, since the first magnetization fixed layers 1a and 1b are formed to extend in the Z direction, their XY plane shapes can be reduced (see FIG. 4). Further, the first magnetization fixed layers 1a and 1b and the magnetization free layer 2 overlap (see FIG. 11B). Therefore, the area of the magnetic memory cell is reduced as compared with the prior art. In the case of the example shown in FIGS. 11A to 11E, the cell area is 12.8F ² .

1-9. Effects The main effects obtained by the present embodiment are as follows.

  First, since data writing is performed by a spin injection method, the writing current can be further reduced as the element is miniaturized. In other words, the minimum current value required for data writing becomes smaller. This means that the write margin is widened.

  In addition, since data writing is performed by the horizontal spin injection method, the write current does not penetrate the MTJ. Since it is not necessary to pass a write current through the tunnel barrier layer 3 for each write, deterioration of the tunnel barrier layer 3 is suppressed. Further, while the read characteristic depends on the property of the MTJ including the tunnel barrier layer 3, the write characteristic mainly depends on the property of the magnetization free layer 2. Therefore, it is possible to design the read characteristic and the write characteristic almost independently. In other words, the write characteristics can be designed without being largely restricted by the read characteristics. That is, the degree of freedom in designing the write characteristics is improved. This also contributes to the expansion of the write margin.

  Furthermore, according to the present embodiment, the first magnetization fixed layer 1 and the magnetization free layer 2 are not formed on the same plane but are arranged three-dimensionally. As a result, the following effects can be further obtained.

  The required magnetic characteristics differ between the region in which the magnetization direction is variable and the region in which the magnetization direction is fixed. However, when these regions exist in the same magnetic layer, it is difficult to adjust the magnetic characteristics for each region. According to the present embodiment, the first magnetization fixed layer 1 and the magnetization free layer 2 can be designed independently. That is, the degree of freedom in design is high. As a result, it is possible to optimize each of the first magnetization fixed layer 1 and the magnetization free layer 2 according to the required magnetic characteristics.

  Further, the magnetization directions of the first magnetization fixed layers 1a and 1b must be fixed so that opposite spin-polarized electrons can be supplied. When the pair of first magnetization fixed layers 1a and 1b and the magnetization free layer 2 are linearly formed on the same plane, it is necessary to fix the magnetizations of the pair of first magnetization fixed layers 1a and 1b in opposite directions. is there. This requires a complicated manufacturing process. In the present embodiment, the magnetizations of the first magnetization fixed layers 1a and 1b are fixed in the same direction (+ Z direction or −Z direction). Therefore, a complicated manufacturing process becomes unnecessary.

  Furthermore, as described in the above section 1-8, the areas of the magnetoresistive element and the magnetic memory cell can be reduced. This contributes to the realization of a large-capacity MRAM.

2. Second Embodiment In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate.

  FIG. 12 is a side view schematically showing the structure of the magnetoresistance effect element according to the second exemplary embodiment. According to the present embodiment, the first magnetization fixed layers 20a and 20b are provided instead of the first magnetization fixed layers 1a and 1b described above. The first magnetization fixed layers 20a and 20b are formed of a material having “crystalline magnetic anisotropy” in the Z direction. Therefore, the magnetization of the first magnetization fixed layers 20a and 20b can be easily fixed. Further, it is not necessary to increase the aspect ratio in the Z direction of the first magnetization fixed layers 20a and 20b.

  As the material of the first magnetization fixed layers 20a and 20b, a transition metal such as Fe, Co, Ni, or an alloy made of them, and a material exhibiting perpendicular magnetic anisotropy can be used. For example, an alloy composed of a transition metal element such as Fe, Co, or Ni and a nonmagnetic element such as Pd, Pt, Tb, or Gd, particularly a regular alloy is preferable. In addition, an artificial lattice made of a transition metal such as Fe, Co, or Ni or an alloy made of them can be used as a material. Moreover, you may adjust characteristics, such as a magnetic characteristic, crystallinity, a mechanical characteristic, and a chemical characteristic, by adding a nonmagnetic element to these magnetic metals and magnetic alloys. Regarding the first magnetization fixed layers 20a and 20b, it is desirable that the magnetic anisotropy is appropriately large and the spin polarizability is high.

  The write operation and the read operation are the same as those in the first embodiment (see FIGS. 2 and 3). Similarly to the first embodiment, the planar shape, the side surface shape, the positional relationship, and the like of the first magnetization fixed layers 20a and 20b and the magnetization free layer 2 can take various patterns (FIG. 4, FIG. 5A to FIG. 5). FIG. 5C, FIGS. 6A to 6C, and FIGS. 7A to 7D). The circuit configuration and layout are the same as those in the first embodiment (see FIGS. 8 to 10 and FIGS. 11A to 11E). Also by the structure according to the present embodiment, the same effect as the first embodiment can be obtained.

3. Third Embodiment In the third embodiment, the same reference numerals are given to the same components as those in the above-described embodiments, and overlapping descriptions are omitted as appropriate.

  FIG. 13 is a side view schematically showing the structure of the magnetoresistance effect element according to the third exemplary embodiment. According to the present embodiment, the first magnetization fixed layer 1a (20a) is connected to one end of the magnetization free layer 2 via the conductive layer 30a. The first magnetization fixed layer 1b (20b) is connected to the other end of the magnetization free layer 2 through the conductive layer 30b. As a material of the conductive layer 30, a metal element or a compound having a low electric resistance such as Au, Ag, Cu, Nb, Mo, Hf, Ta, W, Al, Ti, ZrN, or TiN can be used. The conductive layer 30 also serves as a seed layer for crystal growth of the magnetization free layer 2.

  FIG. 14 shows an example of the magnetization state of the magnetization free layer 2. The fixed magnetization of the first magnetization fixed layer 1 (20) affects the magnetization of the end portion of the magnetization free layer 2, and a magnetization state similar to the magnetization state shown in FIG. 3 is obtained. Therefore, data writing is realized by the same method as the above-described embodiment. At this time, the conductive layer 30 also serves to prevent the temperature rise of the magnetization free layer 2 due to the supply of the write current.

4). Fourth Embodiment In the fourth embodiment, the same reference numerals are given to the same components as those in the above-described embodiments, and overlapping descriptions are omitted as appropriate.

  FIG. 15 is a side view schematically showing the structure of the magnetoresistance effect element according to the fourth exemplary embodiment. According to the present embodiment, the first magnetization fixed layers 1a and 1b (20a and 20b) are arranged to be electrically isolated from the magnetization free layer 2. Instead, the first conductive layer 30a is connected to one end of the magnetization free layer 2, and the second conductive layer 30b is connected to the other end. The materials of the conductive layers 30a and 30b are the same as those in the third embodiment.

  The first magnetization fixed layers 1a and 1b (20a and 20b) are separated from the magnetization free layer 2, but are magnetically coupled to the magnetization free layer 2. Similar to the above-described embodiment, the first magnetization fixed layer 1a (20a) is arranged on one end side of the magnetization free layer 2, and the fixed magnetization affects the magnetization of one end of the magnetization free layer 2. It is exerting. The first magnetization fixed layer 1 b (20 b) is disposed on the other end side of the magnetization free layer 2, and the fixed magnetization affects the magnetization of the other end of the magnetization free layer 2. As a result, a magnetization state similar to the magnetization state shown in FIG. 3 is obtained.

  In particular, as shown in FIG. 15, the first magnetization fixed layers 1a and 1b (20a and 20b) are preferably provided outside the conductive layers 30a and 30b. That is, the first magnetization fixed layer 1a (20a) is disposed away from the magnetization free layer 2 in the −X direction, and the second magnetization fixed layer 1b (20b) is disposed away from the magnetization free layer 2 in the + X direction. The In that case, the same effect as the “protruding portion Pb” shown in FIGS. 6A to 6C is obtained. In the example shown in FIG. 3, the magnetization MC having a component in the −X direction is almost eliminated, and conversely, the magnetization MB having a component in the + X direction is increased. Further, the + X direction component itself of the magnetization MB also increases. These mean that the supply efficiency of + X direction spin-polarized electrons is increased.

  FIG. 16 shows an example of the magnetization state of the magnetization free layer 2. When writing data, a write current is passed through the magnetization free layer 2 from one of the conductive layers 30a and 30b to the other. At this time, the conductive layer 30 also serves to prevent the temperature rise of the magnetization free layer 2 due to the supply of the write current. As shown in FIG. 16, the X direction component of magnetization is strengthened at the end of the magnetization free layer 2. As a result, the supply efficiency of the X-direction spin-polarized electrons is increased as compared with the above-described embodiment. Therefore, the write current can be further reduced.

5. Fifth Embodiment In the fifth embodiment, the same reference numerals are given to the same components as those in the above-described embodiments, and overlapping descriptions are omitted as appropriate.

  FIG. 17 is a side view schematically showing the structure of the magnetoresistance effect element according to the fifth exemplary embodiment. According to the present embodiment, the assist wiring 40 is provided in the vicinity of the magnetoresistive effect element. When writing data, a predetermined current flows through the assist wiring, thereby generating an assist magnetic field. The assist magnetic field is applied to the magnetization free layer 2 to assist the movement of the domain wall. That is, when writing data, a current is passed through the assist wiring so that an assist magnetic field is generated in such a direction as to assist the domain wall movement in the magnetization free layer 2.

  For example, in FIG. 17, an assist wiring 40 extending in the Y direction is disposed below the magnetization free layer 2 of the magnetoresistive effect element. When moving the domain wall in the + X direction, a current in the + Y direction flows through the assist wiring 40. As a result, an assist magnetic field in the + X direction is applied to the magnetization free layer 2. The magnetization of the magnetization free layer 2 is easily oriented in the + X direction by the assist magnetic field, that is, the domain wall movement in the + X direction is assisted by the assist magnetic field. On the contrary, when the domain wall is moved in the −X direction, a current in the −Y direction flows through the assist wiring 40. The position and the number of the assist wirings 40 are not limited to those shown in FIG.

  Thus, according to the present embodiment, the assist magnetic field generated by the assist wiring 40 is applied to the magnetization free layer 2 simultaneously with the supply of the write current to the magnetization free layer 2. Since the domain wall motion is assisted by the assist magnetic field, the amount of write current to be supplied to the magnetization free layer 2 can be reduced. That is, the value of the write current that is minimum required for the domain wall motion is reduced. This means that the write margin is widened.

  FIG. 18 shows an example of the layout of the assist wiring 40. In FIG. 18, the assist wiring 40 is arranged between the two layers shown in FIGS. 11A and 11B. The assist wiring 40 is formed so as to extend in the Y direction, and is provided in common to a row of magnetic memory cells arranged along the Y direction.

  FIG. 19 shows another example of the layout of the assist wiring 40. In FIG. 19, the assist wiring 40 is connected to one first magnetization fixed layer 1b (20b). In this case, the assist wiring 40 not only generates an assist magnetic field but also serves to supply a write current to the magnetization free layer 2. In other words, a wiring for supplying a write current is also used as the assist wiring 40. At the time of data writing, the write current is supplied to or extracted from the first magnetization fixed layer 1b through the assist wiring 40. At the same time, an assist magnetic field generated by the write current is applied to the magnetization free layer 2. With such a configuration, the number of wirings can be reduced and the circuit area can be reduced.

  20A and 20B show a modified example of the assist wiring 40. The assist wiring 40 shown in FIGS. 20A and 20B has a yoke structure. That is, a part of the surface of the assist wiring 40 that is not opposed to the magnetization free layer 2 is covered with the magnetic body 41. 20A, the bottom surface of the assist wiring 40 is covered with a magnetic body 41, and in FIG. 20B, the side surface and the bottom surface of the assist wiring 40 are covered with a magnetic body 41. With such a yoke structure, the assist magnetic field is increased, and the write current can be further reduced.

FIG. 1A is a side view schematically showing the structure of the magnetoresistive effect element according to the first exemplary embodiment of the present invention. FIG. 1B is a plan view schematically showing the structure of the magnetoresistance effect element according to the first exemplary embodiment of the present invention. FIG. 2 is a diagram for explaining data writing to the magnetoresistive effect element according to the first embodiment. FIG. 3 is a diagram for explaining data writing to the magnetoresistive effect element according to the first embodiment. FIG. 4 is a plan view showing an example of the shape of the first magnetization fixed layer of the magnetoresistive effect element according to the first embodiment. FIG. 5A is a plan view showing an example of the shape of the magnetization free layer of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 5B is a plan view showing another example of the shape of the magnetization free layer of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 5C is a plan view illustrating still another example of the shape of the magnetization free layer of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 6A is a plan view showing an example of a positional relationship between the first magnetization fixed layer and the magnetization free layer of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 6B is a plan view showing another example of the positional relationship between the first magnetization fixed layer and the magnetization free layer of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 6C is a plan view illustrating still another example of the positional relationship between the first magnetization fixed layer and the magnetization free layer of the magnetoresistive effect element according to the first embodiment. FIG. 7A is a side view showing a modification of the magnetoresistive effect element according to the first exemplary embodiment. FIG. 7B is a side view showing another modification of the magnetoresistive effect element according to the first exemplary embodiment. FIG. 7C is a side view showing still another modified example of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 7D is a side view showing still another modification of the magnetoresistance effect element according to the first exemplary embodiment. FIG. 8 is a circuit diagram schematically showing the configuration of the magnetic memory cell according to the embodiment of the present invention. FIG. 9 is a circuit diagram schematically showing a configuration of the MRAM according to the embodiment of the present invention. FIG. 10 is a cross-sectional view showing the structure of the magnetic memory cell according to the embodiment of the present invention. FIG. 11A is a plan view showing a structure in the layer LA in FIG. FIG. 11B is a plan view showing the structure of the layer LB in FIG. FIG. 11C is a plan view showing the structure of the layer LC in FIG. FIG. 11D is a plan view showing the structure of the layer LD in FIG. FIG. 11E is a plan view showing the structure of the layer LE in FIG. FIG. 12 is a side view schematically showing the structure of the magnetoresistive element according to the second embodiment of the invention. FIG. 13 is a side view schematically showing the structure of a magnetoresistive element according to the third embodiment of the invention. FIG. 14 is a diagram for explaining data writing to the magnetoresistive effect element according to the third embodiment. FIG. 15 is a side view schematically showing the structure of the magnetoresistive element according to the fourth embodiment of the invention. FIG. 16 is a diagram for explaining data writing to the magnetoresistive effect element according to the fourth embodiment. FIG. 17 is a side view schematically showing the structure of the magnetoresistive element according to the fifth embodiment of the invention. FIG. 18 is a plan view showing a layout example of the assist wiring in the fifth embodiment. FIG. 19 is a plan view showing another layout example of the assist wiring in the fifth embodiment. FIG. 20A is a side view showing a modification of the magnetoresistance effect element according to the fifth exemplary embodiment. FIG. 20B is a side view showing another modification of the magnetoresistance effect element according to the fifth exemplary embodiment.

Explanation of symbols

1, 1a, 1b First magnetization fixed layer 2 Magnetization free layer (free layer)
3 Tunnel barrier layer 4 Second magnetization fixed layer (pinned layer)
10, 10a, 10b Select transistor 11, 11a, 11b Bit line 12 Word line 13 Ground line 14 Metal layer 15 Via 16 Semiconductor substrate 17 Element isolation structure 18 Diffusion layer 19 Electrode layer 20 First magnetization fixed layer 30 Conductive layer 40 Assist wiring 41 Magnetic body 100 MRAM
110 Magnetic Memory Cell 120 X Selector 130 Y Selector 140 Y Side Current Termination Circuit DW Domain Wall

Claims (18)

At least two first magnetization fixed layers having fixed magnetization directions;
A magnetization free layer formed on the first plane and having a variable magnetization direction;
A second magnetization fixed layer connected to the magnetization free layer via a nonmagnetic layer and having a magnetization direction fixed;
The two first magnetization fixed layers are disposed so as to face the second magnetization fixed layer with the magnetization free layer interposed therebetween, and are magnetically coupled to the magnetization free layer,
Both the magnetizations of the two first magnetization fixed layers have a component in a first direction perpendicular to the first plane,
A magnetoresistive element in which a write current is caused to flow from one end to the other end of the magnetization free layer in the first plane during data writing. The magnetoresistive element according to claim 1,
One of the two first magnetization fixed layers is disposed on the one end side of the magnetization free layer,
The other of the two first magnetization fixed layers is disposed on the other end side of the magnetization free layer,
The magnetization of the one first magnetization fixed layer gives a magnetic force in a second direction perpendicular to the first direction to the magnetization of the magnetization free layer,
Magnetization of the other first magnetization fixed layer gives a magnetic force in a third direction antiparallel to the second direction to the magnetization of the magnetization free layer. The magnetoresistive effect element according to claim 2,
The one first magnetization fixed layer is connected to the one end of the magnetization free layer,
The other first magnetization fixed layer is connected to the other end of the magnetization free layer. The magnetoresistive effect element according to claim 2,
The one first magnetization fixed layer is connected to the one end of the magnetization free layer through a first conductive layer,
The other first magnetization fixed layer is connected to the other end of the magnetization free layer via a second conductive layer. The magnetoresistive effect element according to claim 3 or 4,
At the time of data writing, the write current flows from the one first magnetization fixed layer to the other first magnetization fixed layer through the magnetization free layer. The magnetoresistive effect element according to any one of claims 3 to 5,
When viewed from the first direction,
The planar shape of the one first magnetization fixed layer protrudes outside the planar shape of the magnetization free layer in a direction away from the other end,
A magnetoresistive effect element, wherein the planar shape of the other first magnetization fixed layer protrudes from the planar shape of the magnetization free layer in a direction away from the one end. The magnetoresistive effect element according to claim 2,
The two first magnetization fixed layers are arranged away from the magnetization free layer. Magnetoresistive effect element. The magnetoresistive element according to claim 7,
The one first magnetization fixed layer is disposed away from the magnetization free layer in a direction away from the other end,
The other first magnetization fixed layer is disposed away from the magnetization free layer in a direction away from the one end. Magnetoresistive element. The magnetoresistive effect element according to claim 7 or 8,
A first conductive layer connected to the one end of the magnetization free layer;
A second conductive layer connected to the other end of the magnetization free layer,
When writing data, the write current flows from the first conductive layer through the magnetization free layer to the second conductive layer. The magnetoresistive effect element according to any one of claims 2 to 9,
The two first magnetization fixed layers have a taper structure that expands toward the magnetization free layer. Magnetoresistive element. The magnetoresistive effect element according to any one of claims 2 to 9,
The two first magnetization fixed layers are formed such that a longitudinal direction is inclined with respect to the first plane. The magnetoresistive effect element according to any one of claims 2 to 9,
The magnetization free layer has a taper structure that expands toward the two first magnetization fixed layers. Magnetoresistive element. The magnetoresistive effect element according to any one of claims 1 to 12,
The two first magnetization fixed layers have a magnetoresistive effect in the first direction. The magnetoresistive effect element according to any one of claims 1 to 12,
The two first magnetization fixed layers have magnetocrystalline anisotropy in the first direction. The magnetoresistive effect element according to any one of claims 1 to 14,
The magnetization free layer is
A first region located on the one end side with respect to the center of the one end and the other end and having a cross-sectional area different from the cross-sectional area at the center;
A magnetoresistive effect element including: a second region located on the other end side with respect to the center and having a cross-sectional area different from the cross-sectional area at the center. Comprising a plurality of magnetic memory cells arranged in an array;
Each of the plurality of magnetic memory cells includes:
A magnetoresistive effect element according to any one of claims 1 to 15,
A transistor for supplying the write current to the magnetization free layer when the data is written; The MRAM according to claim 16, wherein
An MRAM in which an external magnetic field is applied to the magnetization free layer simultaneously with the supply of the write current during the data writing. The MRAM according to claim 17, wherein
A wiring for supplying the write current to the magnetization free layer;
The MRAM in which the external magnetic field is generated simultaneously by the write current flowing through the wiring during the data writing.

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