JP2012009786A - Memory device - Google Patents

Abstract

The present invention provides a memory element capable of recording information with a spin injection current that can be recorded with a small current while being able to hold the recording stably and can be used practically.
A reference layer with a determined magnetization direction, a recording layer whose magnetization direction changes depending on recording information, a nonmagnetic layer provided between the reference layer and the recording layer, And a memory element stack 7 that records information on the recording layer 5 with a spin injection current. Furthermore, the piezoelectric element 11 provided in the side part of the memory element laminated body 7 and a means for applying an electric field to the piezoelectric element 11 are provided.
[Selection] Figure 1

Description

  The present invention relates to a memory element, particularly a nonvolatile memory.

  In information devices such as computers, DRAMs with high speed and high density are widely used as random access memories. However, since DRAM is a volatile memory in which information disappears when the power is turned off, a nonvolatile memory in which information does not disappear is desired.

  As a candidate for a nonvolatile memory, a magnetic random access memory (MRAM) that records information by magnetization of a magnetic material has attracted attention and is being developed. There are two methods for recording in the MRAM: a method of reversing magnetization by a current magnetic field, and a method of injecting spin-polarized electrons directly into the recording layer to cause magnetization reversal (see Patent Document 1). Currently, attention is focused on spin-injection magnetization reversal, which can reduce the recording current as the element size decreases.

  However, when the element size is reduced, there is a problem in the recording holding capability such that the information of recording changes due to thermal fluctuation. To avoid this, it is necessary to take measures such as increasing the magnetic layer thickness of the recording layer. However, increasing the volume of the magnetic layer increases the current required for spin injection magnetization reversal, increasing power consumption and driving. This increases the size of the transistor and makes it difficult to improve the recording density.

  Patent Document 2 proposes a memory element that reduces the recording current by reducing the thermal disturbance resistance by extending the lattice in the in-plane direction of the recording layer by using expansion and contraction of the piezoelectric layer. Japanese Patent Application Laid-Open No. 2004-228561 discloses a basic configuration in which a piezoelectric layer, a recording layer, a tunnel barrier layer, and a reference layer are stacked.

JP 2004-193595 A JP 2010-80733 A

  In view of the above-described points, the present invention provides a memory element that can record with a small current while being able to stably maintain recording and can be practically used.

  A memory element according to the present invention includes a reference layer having a determined magnetization direction, a recording layer whose magnetization direction changes depending on recording information, and a nonmagnetic layer provided between the reference layer and the recording layer. A memory element stack that records information on the recording layer with a spin injection current. Furthermore, a piezoelectric body provided on a side portion of the memory element stacked body and means for applying an electric field to the piezoelectric body are provided.

  The memory element of the present invention has a reference layer, a nonmagnetic layer, and a recording layer, and a piezoelectric body is provided on the side of the memory element stack that records information on the recording layer with a spin injection current. The stress based on the deformation of the piezoelectric body can be effectively applied to the layer. Thereby, the coercive force of the recording layer is reduced, and the recording current is reduced.

  According to the memory element of the present invention, it is possible to provide a memory element, that is, a non-volatile memory that can be recorded with a small current while being able to stably maintain recording, and can be used practically.

1A to 1C are a perspective view, a cross-sectional view, and an operation explanatory view showing a schematic configuration of a first embodiment of a memory element according to the present invention. A and B are a top view and a cross-sectional view showing a schematic configuration of a second embodiment of a memory element according to the present invention. FIGS. 8A to 8C are explanatory diagrams showing a state of a piezoelectric body before voltage application, a state of a piezoelectric body after voltage application, and a deformation state of a recording layer accompanying deformation of the piezoelectric body, which are used for explaining the operation of the second embodiment. A and B are a top view and a cross-sectional view showing a schematic configuration of a third embodiment of a memory element according to the present invention. It is explanatory drawing with which it uses for operation | movement description of 3rd Embodiment. It is sectional drawing which shows schematic structure of 4th Embodiment of the memory element which concerns on this invention. AD is a manufacturing process diagram showing an example of a manufacturing method of the memory element according to the fourth embodiment. It is explanatory drawing with which it uses for operation | movement description of 4th Embodiment. It is sectional drawing which shows schematic structure of 5th Embodiment of the memory element based on this invention. It is sectional drawing which shows schematic structure of 6th Embodiment of the memory element based on this invention. It is sectional drawing which shows schematic structure of 7th Embodiment of the memory element based on this invention. It is sectional drawing which shows schematic structure of 8th Embodiment of the memory element based on this invention. A, B It is sectional drawing which shows schematic structure of 9th Embodiment of the memory element based on this invention. FIGS. 6A to 6D are manufacturing process diagrams illustrating a method for manufacturing a sample of a memory element using an in-plane magnetic film for verifying the effect of the memory element of the present invention. FIGS. FIG. 15 is a detailed view of the memory element body of FIG. 14. It is a graph which shows the relationship between the voltage (Va) applied to a piezoelectric material when using the sample of FIG. 14, and the coercive force of a perpendicular magnetization film. 15 is a graph showing a relationship between a writing (recording) voltage (Vp) and a reversal error when the sample of FIG. 14 is used and the voltage applied to the piezoelectric body is changed. It is a sample used for verification of the effect of the present invention and is a schematic configuration diagram using a perpendicular magnetization film. It is a graph which shows the relationship between the voltage (Va) applied to a piezoelectric material when using the sample of FIG. 18, and the coercive force of a perpendicular magnetization film.

Hereinafter, modes for carrying out the invention (hereinafter referred to as embodiments) will be described. The description will be given in the following order.
1. 1. Outline of memory device according to embodiment of the present invention First Embodiment (Schematic configuration example of memory element)
3. Second Embodiment (Schematic configuration example of memory element)
4). Third Embodiment (Schematic configuration example of memory element)
5. Fourth Embodiment (Schematic configuration example of memory element and manufacturing method thereof)
6). Fifth embodiment (schematic configuration example of memory element)
7). Sixth Embodiment (Schematic configuration example of memory element)
8). Seventh Embodiment (Schematic configuration example of memory element)
9. Eighth Embodiment (Schematic configuration example of a memory element)
10. Ninth Embodiment (Schematic configuration example of memory element)
11. Verification of the effect of the memory device of the present invention

<Overview of Memory Element According to Embodiment of the Present Invention>
The memory element according to the embodiment of the present invention includes a nonmagnetic layer between a reference layer (magnetic layer) serving as a reference for information and a recording layer (magnetic layer) whose magnetization direction changes according to recorded information. It has a memory element stack with a basic structure sandwiched. Paired electrodes are disposed on the front and back surfaces of the memory element stack. In this memory element, a piezoelectric body is disposed at a position that exerts a mechanical action on the recording layer, and when recording information on the recording layer, an electric field is applied to the piezoelectric body to reduce the coercive force of the recording layer. Such a stress is generated to reduce the spin injection current necessary for recording. Alternatively, the memory element is configured to apply an electric field to the piezoelectric body and assist the precession of magnetization of the recording layer by high-frequency vibration to reduce the spin injection current necessary for recording.

  When an electric field is applied to the piezoelectric body, for example, by applying a voltage, the piezoelectric body is deformed by the piezoelectric effect, and the stress on the layers constituting the memory element stack changes. At this time, since a force is also applied to the recording layer, the recording layer is deformed, the magnetic anisotropy is changed by the inverse magnetostrictive effect, and the coercive force is changed. The characteristics of the piezoelectric body, the voltage polarity applied to the piezoelectric body, the magnetostriction constant of the recording layer, and the like are adjusted so that the coercive force of the recording layer decreases when an electric field is applied to the piezoelectric body. Thereby, when a spin injection current is applied while applying an electric field to the piezoelectric body, the reversal current that reverses the magnetization of the recording layer, that is, the spin injection current is reduced. In the memory element, it is preferable to take measures to prevent deformation of the recording layer based on deformation of the piezoelectric body, that is, to easily generate stress in the recording layer.

  Both the reference layer and the recording layer may be in-plane magnetization films or perpendicular magnetization films. In the case of an in-plane magnetized film, it is better that the expansion / contraction rate changes greatly in the easy magnetization direction and the hard magnetization direction when the piezoelectric body is deformed. If the recording layer is formed of an in-plane magnetization film and the magnetostriction of the recording layer is positive, the magnetic anisotropy decreases if the recording layer is pulled in the direction of difficult magnetization or the recording layer is compressed in the direction of easy magnetization However, the coercive force is reduced and recording becomes easy. If the recording layer is formed of an in-plane magnetization film and the magnetostriction of the recording layer is negative, the magnetic anisotropy decreases if the recording layer is pulled in the easy magnetization direction or the recording layer is compressed in the hard magnetization direction. However, the coercive force is reduced and recording becomes easy.

  When the recording layer is formed of a perpendicularly magnetized film and the magnetostriction of the recording layer is positive, if the film surface is pulled uniformly or compressed perpendicularly to the film surface, the magnetic anisotropy decreases and the coercive force decreases. It becomes easy to record. When the recording layer is formed of a perpendicularly magnetized film and the magnetostriction of the recording layer is negative, if the film layer is pulled perpendicularly or compressed uniformly, the magnetic anisotropy decreases and the coercive force decreases. It becomes easy to record.

  When the force applied to the recording layer fluctuates, the magnetization of the recording layer vibrates, but when it vibrates at an appropriate frequency, the magnetization reversal current, that is, the spin is synchronized with the precession of the magnetization of the recording layer due to the spin injection torque. The injection current is reduced. The electrode formed on the memory element laminated body or the electrode formed on the piezoelectric body may be a good conductor metal, but is preferably selected in consideration of the crystal orientation and reaction deterioration of the piezoelectric body and the magnetic layer.

The piezoelectric material may be an oxide such as BaTiO ₃ , LiNbO ₃ , or ZnO, a nitride such as AlN, or an organic material such as polyvinylidene fluoride. As a method for manufacturing the piezoelectric body, a sputtering method, a chemical vapor deposition method, a sol-gel method, a coating method, or the like can be used.

  The piezoelectric body can be disposed on the side of the memory element stack. At that time, the piezoelectric body can be disposed in contact with the memory element stack, or can be disposed away from the memory element stack. The piezoelectric body can also be disposed on the side portion between the reference layer and the recording layer, leaving the nonmagnetic layer. The piezoelectric body can be disposed below or on the memory element stack. The piezoelectric body can also be disposed between the nonmagnetic layer and the reference layer, or between the nonmagnetic layer and the recording layer. The piezoelectric body can also be configured to apply a force to the recording layer by using a physical force transmission means such as an arm arranged at a distance from the recording layer. The piezoelectric body may be arranged by combining a plurality of the above arrangements.

  The electrode formed on the piezoelectric body may be provided exclusively for the piezoelectric body. When the piezoelectric body is incorporated in a part of the recording layer, a part of the reference layer, or a part of the nonmagnetic layer, a piezo effect is generated by an electric field generated by a current flowing during recording of the memory element. The nonmagnetic layer between the reference layer and the recording layer is made of a piezoelectric material, and a spin injection magnetization reversal is caused to the recording layer by a tunnel current (spin injection current) through the nonmagnetic layer by the piezoelectric material. It can also be configured.

  According to the memory element according to the embodiment of the present invention described above, a spin injection current is passed during recording of information, and at the same time, the piezoelectric body is deformed and a force based on the deformation is propagated to the recording layer to maintain the recording layer. Magnetic force can be reduced. Therefore, if this memory element is used, a nonvolatile memory capable of recording with a small spin injection current while having excellent information retention characteristics can be realized.

<2. First Embodiment>
[Schematic configuration example of memory element]
FIG. 1 shows a schematic configuration of a first embodiment of a memory element according to the present invention. As shown in FIGS. 1A and 1B, the memory element 1 according to the first embodiment includes a memory element body 2 and a piezoelectric element 3. The memory element body 2 includes a reference layer (magnetic layer) 4 in which the magnetization direction is determined, a recording layer (magnetic layer) 5 in which the magnetization direction changes depending on recording information, and between the reference layer 4 and the recording layer 5. The provided nonmagnetic layer 6 is laminated, and has a memory element laminated body 7 that records information in the recording layer 5 with a spin injection current. The nonmagnetic layer 6 is called a so-called tunnel barrier film. The memory element body 2 further includes a pair of upper electrodes 8 formed on the front and back surfaces of the memory element stack 7 and a lower portion 9. The piezoelectric element 3 includes a piezoelectric body 11 made of a piezoelectric material and a pair of electrodes 12 and 13 formed on both surfaces of the piezoelectric body 11.

  The piezoelectric body 11 is provided on the side portion of the memory element stack 7. In the present embodiment, the memory element body 2 is disposed on the substrate 15, and the piezoelectric element 3 is disposed slightly apart from the side of the memory element body 2 on the substrate 15. The piezoelectric element 2 is provided with means (not shown) for applying an electric field to the piezoelectric body 11 connected to the electrodes 12 and 13.

  The recording layer 5 and the reference layer 4 are formed of a planar magnetization film, and are formed in a shape having a major axis and a minor axis that are orthogonal, in this example, an elliptical shape or a shape close to an elliptical shape. In this example, the recording layer 5 and the reference layer 4 are formed of a plane magnetic film having a positive magnetostriction. The recording layer 5 and the reference layer 4 are magnetized in the major axis direction with the major axis direction being the easy magnetization direction and the minor axis direction being the magnetization difficult direction. The piezoelectric element 3 selects a piezoelectric material or the like so that the piezoelectric body 11 is compressed and deformed in a direction opposite to the electrodes 12 and 13 when a required voltage is applied to the electrodes 12 and 13 and an electric field is applied to the piezoelectric body 11. Configured. The memory element stacked body 7 is arranged so that the major axis direction thereof is parallel to the compression direction of the piezoelectric body 11.

The substrate 15 serves as a stress propagation member for applying compressive stress to the recording layer 5 by the compressive deformation of the piezoelectric body 11 of the piezoelectric element 3 being propagated to the recording layer 5 of the memory element stack 7. The substrate 15 is formed of a laminated substrate in which a soft member 17 is disposed below the hard member 16 so that the substrate 15 is easily deformed based on the deformation of the piezoelectric body 11, that is, stress is easily transmitted. The rigid member may be for example a _{SiO 2, Al 2 O 3,} Si 3 N 4 ceramic material or the like. As the soft member, a metal such as Au or an organic material such as a thermosetting resist material can be used.

  Next, the operation of the memory element 1 according to the first embodiment will be described. When information is recorded, a spin injection current flows through the recording layer 5 through the upper electrode 8 and the lower electrode 9 of the memory element body 2. Simultaneously with the supply of the spin injection current, a required voltage is applied to the piezoelectric element 3 and an electric field is applied to the piezoelectric body 11. As shown in FIG. 1C, this electric field causes the piezoelectric body 11 to compress and deform under the force F1 in the opposing direction of the electrodes 12 and 13. This force F1 is transmitted to the substrate 15 and further to the memory element body 3, and a compressive stress in the major axis direction is induced in each layer of the memory element stack. At this time, the force F1 propagates to the recording layer 5 and is compressed and deformed in the major axis direction. Since the recording layer 5 is formed of a plane magnetic film having a positive magnetostriction, the recording layer 5 receives a compressive stress in the major axis direction, so that the magnetic anisotropy is weakened due to the inverse magnetostriction effect, and the holding power of the recording layer 5 is reduced. . A decrease in coercive force of the recording layer 5 can reduce the spin injection current.

  Here, when the voltage applied to the piezoelectric body 11 is a high-frequency voltage, the frequency is preferably 1 GHz or more and 10 GHz or less. Outside this range, the effect of reducing the spin injection current of the present invention becomes too small, which is not preferable. The above frequency range can also be applied to the following embodiments.

  According to the memory element 1 according to the first embodiment, the piezoelectric element 3 is disposed so as to exert a force on the recording layer 5 of the memory element body 2, and the voltage is applied to the piezoelectric element 3 while the memory element stack 7 is applied. By causing the spin injection current to flow, the spin injection current can be reduced. Therefore, it is possible to provide a non-volatile memory that can be recorded with a small spin injection current while maintaining stable recording and that can be used practically.

[Modification]
In FIG. 1, the memory element 1 in which the recording layer 5 and the reference layer 4 are formed of a plane magnetic film having a positive magnetostriction has been described. On the other hand, the present invention can also be applied to a memory element in which the recording layer 5 and the reference layer 4 are formed of a plane magnetic film having a negative magnetostriction. In this case, the piezoelectric element 2 of FIG. 1 is arranged on the substrate 15 so that the deformation direction of the piezoelectric body 11 is parallel to the short axis direction of the recording layer and the reference layer made of the plane magnetization film having a negative magnetostriction. Composed. According to this configuration, the piezoelectric body 11 is compressed and deformed during recording, and accordingly, the recording layer 5 of the memory element body 2 is compressed and deformed in the minor axis direction through the substrate 15. Since the recording layer 5 is formed of a plane magnetization film having a negative magnetostriction, the magnetic anisotropy is weakened by the inverse magnetostriction effect due to the compressive stress in the minor axis direction, and the coercive force of the recording layer 5 is reduced. A decrease in coercive force of the recording layer 5 can reduce the spin injection current. Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

<3. Second Embodiment>
FIG. 2 shows a schematic configuration of a second embodiment of the memory element according to the present invention. FIG. 2A is a schematic top view including a memory element stack and a piezoelectric body disposed on the side thereof, and FIG. 2B is a schematic cross-sectional view of the memory element. A memory element 21 according to the second embodiment includes a memory element body 2 and a piezoelectric body 11. As described above, the memory element body 2 includes a reference layer (magnetic layer) 4, a recording layer (magnetic layer) 5, and a nonmagnetic layer 6 provided between the reference layer 4 and the recording layer 5. The memory element stack 7, and the upper electrode 8 and the lower electrode 9 formed on the front and back surfaces of the memory element stack 7. The lower electrode 9 is formed larger, and the memory element stack 7 and the upper electrode 8 are stacked on the lower electrode 9.

  The recording layer 5 and the reference layer 4 are formed of a planar magnetization film, and are formed in a shape having a major axis and a minor axis that are orthogonal, in this example, an elliptical shape or a shape close to an elliptical shape. In this example, the recording layer 5 and the reference layer 4 are formed of a plane magnetic film having a positive magnetostriction. The recording layer 5 and the reference layer 4 are magnetized in the major axis direction with the major axis direction being the easy magnetization direction and the minor axis direction being the magnetization difficult direction.

  On the other hand, the piezoelectric body 11 exists on the lower electrode 9 and is disposed on both sides of the memory element stack 7 in the minor axis direction. The piezoelectric body 11 needs to be mechanically connected to the memory element stack 7, particularly the recording layer 5. As will be described later, when a tensile stress is applied to the recording layer, the piezoelectric body 11 needs to be mechanically connected to the memory element stack 7 by adhesion or the like. Therefore, the piezoelectric body 11 of this example is connected to the surface of the lower electrode 9, connected to the side surface of the memory element stacked body 7 from the reference layer 4 to the recording layer 5, and further partially on the surface of the recording layer 5. It is formed having an inverted L-shaped cross section. An extension portion of the piezoelectric body 11 is also connected to the surface of the recording layer 5. The piezoelectric body 11 is configured by selecting a piezoelectric material or the like so as to receive an electric field 23 generated in the nonmagnetic layer between the recording layer and the reference layer during recording and to be deformed by extension.

  Further, a recording voltage source 22 is connected between the upper electrode 8 and the lower electrode 9. The recording voltage source 22 serves both as a spin injection current supply source that supplies a spin injection current to the memory element stack 7 and a voltage supply source that applies an electric field to the piezoelectric body 11.

  Next, the operation of the memory element 21 according to the second embodiment will be described. First, the state of the piezoelectric body 11 before recording is not deformed at all because no electric field is applied as shown in FIG. 3A. At the time of recording information, a spin injection current flows from the recording voltage source 22 to the recording layer 5 through the upper electrode 8 and the lower electrode 9 of the memory element body 2. At the same time, an electric field 23 is generated between the reference layer 4 and the recording layer 5 sandwiching the nonmagnetic layer 6, and this electric field 23 is applied to the piezoelectric body 11. In the piezoelectric body 11, the portion receiving the electric field 23 extends in the vertical direction (see arrow b). Along with this elongation, the entire piezoelectric body 11 is deformed in the direction of arrow a as shown in FIG. 3B. That is, the inside of the piezoelectric body 11 extends and the outside does not change. As a result, the columnar portion of the piezoelectric body 11 warps and deforms in the direction of arrow a. As shown in FIG. 3C, the piezoelectric elements 11 disposed on both sides of the memory element stack 7 in the short axis direction are deformed in a direction away from the memory element stack 7, so that the recording layer 5 is pulled in the short axis direction. The recording layer 5 is deformed, and a tensile stress in the minor axis direction is generated. Since the recording layer 5 is formed of a plane magnetization film having a positive magnetostriction, when receiving the tensile stress in the minor axis direction, the magnetic anisotropy is weakened by the inverse magnetostriction effect, and the holding power of the recording layer 5 is reduced. . A decrease in coercive force of the recording layer 5 can reduce the spin injection current.

  According to the memory element 21 according to the second embodiment, the piezoelectric element 11 is arranged so as to exert a force on the recording layer 5 of the memory element body 2, and an electric field is applied to the piezoelectric element 11, while the memory element stack 7. The spin injection current can be reduced by passing the spin injection current through Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

[Modification]
In FIG. 2, the memory element 21 in which the recording layer 5 and the reference layer 4 are formed of a plane magnetic film having a positive magnetostriction has been described. On the other hand, the present invention can also be applied to a memory element in which the recording layer 5 and the reference layer 4 are formed of a plane magnetic film having a negative magnetostriction. In this case, the piezoelectric body 11 of FIG. 2 is arranged on both sides in the major axis direction of the memory element stack 7. According to this configuration, during recording, the piezoelectric layer 11 is deformed as shown in FIG. 3B, whereby the recording layer 5 is pulled and deformed in the major axis direction. Since the recording layer 5 is formed of a plane magnetization film having a negative magnetostriction, the magnetic anisotropy is weakened by the inverse magnetostriction effect due to the tensile stress in the major axis direction, and the coercive force of the recording layer 5 is reduced. A decrease in coercive force of the recording layer 5 can reduce the spin injection current. Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

<4. Third Embodiment>
[Schematic configuration example of memory element]
FIG. 4 shows a schematic configuration of the third embodiment of the memory element according to the present invention. As shown in FIGS. 4A and 4B, the memory element 25 according to the third embodiment includes a memory element body 2 and a piezoelectric body 11. As described above, the memory element body 2 includes a reference layer (magnetic layer) 4, a recording layer (magnetic layer) 5, and a nonmagnetic layer 6 provided between the reference layer 4 and the recording layer 5. The memory element stack 7, and the upper electrode 8 and the lower electrode 9 formed on the front and back surfaces of the memory element stack 7. The lower electrode 9 is formed larger, and the memory element stack 7 and the upper electrode 8 are stacked on the lower electrode 9.

  The recording layer 5 and the reference layer 4 are formed of a perpendicular magnetization film, and are formed in a circular shape having a required thickness. In this example, the recording layer 5 and the reference layer 4 are formed of perpendicular magnetization films having a negative magnetostriction. The piezoelectric body 11 is formed in a cylindrical shape so as to be in contact with the surface of the lower electrode 9 and to be in contact with the outer surface of the memory element stack 7 or mechanically connected thereto. A metal film 26 is formed on the outer peripheral surface of the cylindrical piezoelectric body 11 so as to be in contact with or mechanically connected to the piezoelectric body 11 and to be electrically connected to the lower electrode 9. As described above, the piezoelectric body 11 needs to be mechanically connected to the memory element stack 7, particularly the recording layer 5. As described later, when compressive stress is applied to the recording layer, the piezoelectric body 11 may be disposed so as to be in contact with the memory element stack 7. Alternatively, the piezoelectric body 11 can be mechanically connected to the memory element stack 7. The piezoelectric body 11 is configured by selecting a piezoelectric material or the like so as to cause a deformation that increases the thickness when an electric field is received in the thickness direction of the cylindrical shape.

  Further, a recording voltage source 22 is connected between the upper electrode 8 and the lower electrode 9. The recording voltage source 22 serves both as a spin injection current supply source that supplies a spin injection current to the memory element stack 7 and a voltage supply source that applies an electric field to the piezoelectric body 11.

  Next, the operation of the memory element 25 according to the third embodiment will be described. At the time of recording information, a spin injection current flows from the recording voltage source 22 to the recording layer 5 through the upper electrode 8 and the lower electrode 9 of the memory element body 2. At this time, an electric field 27 is generated between the recording layer 5 connected to the upper electrode 8 and the metal film 26 connected to the lower electrode 9 at the same time. That is, the electric field 27 is applied to the inside corresponding to the recording layer 5 of the piezoelectric body 11 (see FIG. 4B). The piezoelectric body 11 is deformed so that the portion receiving the electric field 27 extends in the thickness direction. As shown in FIG. 5, along with the deformation of the piezoelectric body 11, the recording layer 5 receives a compressive stress by applying a force from the outer periphery. Since the circular recording layer 5 is formed of a perpendicularly magnetized film having a negative magnetostriction, the magnetic anisotropy is weakened by the inverse magnetostriction effect due to the compressive stress, and the coercive force of the recording layer 5 is reduced. A decrease in coercive force of the recording layer 5 can reduce the spin injection current.

  According to the memory element 25 according to the third embodiment, the piezoelectric element 11 is arranged so as to exert a force on the recording layer 5 of the memory element body 2, and an electric field is applied to the piezoelectric element 11, while the memory element stack 7. The spin injection current can be reduced by passing the spin injection current through Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

[Modification]
In FIG. 4, the memory element 25 in which the recording layer 5 and the reference layer 4 are formed of a perpendicular magnetization film having a negative magnetostriction has been described. On the other hand, the present invention can also be applied to a memory element in which the recording layer 5 and the reference layer 4 are formed by a perpendicular magnetization film having a positive magnetostriction. In this case, the piezoelectric body 11 of FIG. 4 is configured to give a tensile stress to the recording layer 5. For this reason, the piezoelectric body 11 is disposed so as to be mechanically connected to the memory element stack 7. In this way, a tensile stress can be applied to the recording layer 5 by deformation of the piezoelectric body 11 during recording. Since the recording layer 5 is formed of a perpendicular magnetization film having a positive magnetostriction, the magnetic anisotropy is weakened due to the inverse magnetostriction effect, and the coercive force of the recording layer 5 is reduced. A decrease in coercive force of the recording layer 5 can reduce the spin injection current. Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

<5. Fourth Embodiment>
[Schematic configuration example of memory element]
FIG. 6 shows a schematic configuration of the fourth embodiment of the memory element according to the present invention. A memory element 31 according to the fourth embodiment includes a memory element body 2 and a piezoelectric body 11 provided on a side portion of the memory element stack. As described above, the memory element body 2 includes a reference layer (magnetic layer) 4, a recording layer (magnetic layer) 5, and a nonmagnetic layer 6 provided between the reference layer 4 and the recording layer 5. The memory element stack 7, and the upper electrode 8 and the lower electrode 9 formed on the front and back surfaces of the memory element stack 7.

  The recording layer 5 and the reference layer 4 can be formed of a planar magnetization film or can be formed of a perpendicular magnetization film. That is, the memory element body 2 can be applied to both the in-plane magnetization film and the perpendicular magnetization film as the recording layer 5 and the reference layer 4.

  On the other hand, the piezoelectric body 11 is formed between the reference layer 4 and the recording layer 5 on the side portion that is not the central portion. That is, the piezoelectric body 11 is formed so as to be embedded on the end portion side between the reference layer 4 and the recording layer 5, leaving the central portion of the nonmagnetic layer. The piezoelectric body 11 is formed of a piezoelectric body that deforms in the thickness direction. For example, the piezoelectric body 11 can be formed of a piezoelectric body that extends and deforms in the thickness direction, or a piezoelectric body that compressively deforms in the thickness direction.

  The recording layer 5 generates compressive stress, tensile stress, or vice versa in the upper and lower portions based on the deformation of the piezoelectric body 11 in the thickness direction. It can be formed of a laminated film. Alternatively, the recording layer 5 can be formed of a nonmagnetic metal film at the top.

  Further, a recording voltage source 22 is connected between the upper electrode 8 and the lower electrode 9. The recording voltage source 22 serves both as a spin injection current supply source that supplies a spin injection current to the memory element stack 7 and a voltage supply source that applies an electric field to the piezoelectric body 11.

[Example of memory device manufacturing method]
FIG. 7 shows an example of a method for manufacturing the memory element 31 according to the fourth embodiment, in particular, a method for manufacturing a memory element laminated body in which the piezoelectric body is embedded. FIG. 7 is a schematic view of a method of forming the piezoelectric body 11 in the nonmagnetic layer 6. First, as shown in FIG. 7A, a memory element stack 7 in which a reference layer 4, a nonmagnetic layer 6, and a recording layer 5 are stacked is formed.

  Next, as shown in FIG. 7B, a part of the nonmagnetic layer is selectively removed by chemical etching or the like. That is, the end portion side is selectively removed leaving the central portion of the nonmagnetic layer 6 to form the gap 33.

  Next, as shown in FIG. 7C, the piezoelectric material 11A is filled into the gap 33 from which the nonmagnetic layer 6 has been removed by, for example, a sol-gel method or a CVD method. At this time, the piezoelectric material 11 </ b> A is also attached to the outer periphery of the memory element stack 7.

  Next, as shown in FIG. 7D, the piezoelectric material 11A attached to the outer periphery of the memory element stack 7 is removed. As a result, the memory element stack 7 in which the piezoelectric body 11 is embedded, leaving the central nonmagnetic layer 6 between the reference layer 4 and the recording layer 5 is obtained.

  Next, the operation of the memory element 31 according to the fourth embodiment will be described. At the time of recording information, a spin injection current flows from the recording voltage source 22 to the recording layer 5 through the upper electrode 8 and the lower electrode 9 of the memory element body 2. At this time, an electric field is simultaneously applied to the piezoelectric body 11 sandwiched between the recording layer 5 and the reference layer 4. With this electric field, for example, as shown in FIG. 8, when the piezoelectric body 11 is deformed so as to extend in the thickness direction, the recording layer 5 is deformed so as to be concave downward, so that the upper portion of the recording layer 5 is Compressive stress is generated by compression, and the lower portion is pulled to generate tensile stress.

  When the recording layer 5 is formed of an in-plane magnetized film, the upper part of the recording layer 5 where the compressive stress is generated is formed of an in-plane magnetized film with a positive magnetostriction, and the lower part where the tensile stress is generated is in-plane magnetization with a negative magnetostriction. If formed of a film, the magnetic anisotropy is weakened by the inverse magnetostrictive effect, and the coercive force of the recording layer 5 is lowered. A decrease in coercive force of the recording layer 5 can reduce the spin injection current. When the recording layer 5 is formed of a perpendicular magnetization film, the upper portion where the compressive stress of the recording layer 5 is formed is formed of a perpendicular magnetization film having a negative magnetostriction, and the lower portion where the tensile stress is generated is formed of a perpendicular magnetization film having a positive magnetostriction. If so, the magnetic anisotropy is weakened by the inverse magnetostriction effect, and the coercive force of the recording layer 5 is lowered. A decrease in coercive force of the recording layer 5 can reduce the spin injection current.

  Although not shown, when the piezoelectric body 11 is deformed so as to shrink in the thickness direction by the electric field, the lower portion of the recording layer 5 is compressed by deforming the recording layer 5 to be convex upward. A compressive stress is generated, and the upper part is pulled to generate a tensile stress. When the recording layer 5 is formed of an in-plane magnetization film, the lower portion of the recording layer 5 where the compressive stress is generated is formed of an in-plane magnetization film having a positive magnetostriction, and the upper portion where the tensile stress is generated is in-plane magnetization having a negative magnetostriction. If formed of a film, the magnetic anisotropy is weakened by the inverse magnetostrictive effect, and the coercive force of the recording layer 5 is lowered. A decrease in coercive force of the recording layer 5 can reduce the spin injection current. When the recording layer 5 is formed of a perpendicular magnetization film, the lower portion of the recording layer 5 where the compressive stress is generated is formed of a perpendicular magnetization film having a negative magnetostriction, and the upper portion where the tensile stress is generated is formed of a perpendicular magnetization film having a positive magnetostriction. If so, the magnetic anisotropy is weakened by the inverse magnetostriction effect, and the coercive force of the recording layer 5 is lowered. A decrease in coercive force of the recording layer 5 can reduce the spin injection current.

  Further, the recording layer 5 is not configured to change the polarity of magnetostriction between the upper part and the lower part in FIG. 8, and if the upper part is made of a nonmagnetic metal layer, the influence of the upper part can be eliminated and the spin injection current can be reduced. .

  According to the memory element 31 according to the fourth embodiment, the spin injection current can be reduced by applying the spin injection current to the memory element stack 7 while applying an electric field to the piezoelectric body 11 as described above. Can do. Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

<6. Fifth embodiment>
[Schematic configuration example of memory element]
FIG. 9 shows a schematic configuration of the fifth embodiment of the memory element according to the present invention. A memory element 35 according to the fifth embodiment is configured by stacking a piezoelectric element 37 and a memory element body 2 on a substrate 36. As described above, the memory element body 2 includes a reference layer (magnetic layer) 4, a recording layer (magnetic layer) 5, and a nonmagnetic layer 6 provided between the reference layer 4 and the recording layer 5. The memory element stack 7, and the upper electrode 8 and the lower electrode 9 formed on the front and back surfaces of the memory element stack 7. The piezoelectric element 37 is formed by laminating one electrode 38, the piezoelectric body 11 and the other electrode 39 on the surface of the substrate 36. The other electrode 39 is shared with the lower electrode 9 of the memory element body 2.

  As described in the above embodiment, the recording layer 5 and the reference layer 4 are formed by selecting the plane magnetization film or the main direct magnetization film, and the magnetostriction polarity.

  The piezoelectric body 11 of the piezoelectric element 37 is configured such that the film thickness changes due to the piezoelectric effect. The upper electrode 8 of the memory element body 2 is formed in a concave shape having a gap 41 so that the memory element stacking portion 7 is easily deformed based on deformation of the piezoelectric element. The upper electrode 8 is embedded in the piezoelectric element 37 and the memory element body 2 by an insulating filler layer 42 made of, for example, a silicon oxide film.

  Although not shown, a voltage supply source for applying a required voltage is connected between the pair of electrodes 38 and 39 (9) of the piezoelectric element 37. Further, a recording voltage source for flowing a spin injection current is connected between the upper electrode 8 and the lower electrode 9 of the memory element body 2.

  Next, the operation of the memory element 35 according to the fifth embodiment will be described. At the time of recording information, a spin injection current is applied to the recording layer 5 of the memory element body 2 and at the same time, a voltage is applied to the piezoelectric element 37 to deform the piezoelectric body 11 in the thickness direction. The deformation in the thickness direction of the piezoelectric body 11 propagates to the recording layer 5 to deform the recording layer 5. The magnetic anisotropy of the recording layer 5 is weakened by the inverse magnetostrictive effect, the coercive force is lowered, and the spin injection current is reduced. To do.

According to the memory element 35 of the fifth embodiment, the spin injection current can be reduced by causing the spin injection current to flow through the memory element stack 7 while applying a voltage to the piezoelectric element 37 as described above. Can do. Therefore, it is possible to provide a non-volatile memory that can be recorded with a small spin injection current while maintaining stable recording and that can be used practically.
Furthermore, in the present embodiment, since the upper electrode 8 of the memory element body 2 is formed in a concave shape having the gap 41, the recording layer 5 can be easily deformed based on the deformation of the piezoelectric element 37. Further, since the other electrode 39 of the piezoelectric element 37 and the lower electrode 9 of the memory element body 2 are shared, the entire configuration of the memory element 35 can be simplified.

[Modification]
The memory element 35 shown in FIG. 9 is configured by arranging the piezoelectric element 37 in the lower part of the memory element body 2. However, although not shown, the piezoelectric element 37 may be arranged in the upper part of the memory element body 2. . In this case, the upper electrode 9 is formed in a planar shape and is shared with one electrode 38 of the piezoelectric element 37. Even in the memory element having such a configuration, the spin injection current can be reduced by applying a spin injection current to the memory element stack 7 while applying a voltage to the piezoelectric element 37. Therefore, it is possible to provide a non-volatile memory that can be recorded with a small spin injection current while maintaining stable recording and that can be used practically.

<7. Sixth Embodiment>
[Schematic configuration example of memory element]
FIG. 10 shows a schematic configuration of the sixth embodiment of the memory element according to the present invention. Similar to the fifth embodiment, the memory element 45 according to the sixth embodiment is configured by stacking a piezoelectric element 37 and a memory element body on a substrate 36.

In the present embodiment, the air gap 46 is formed at a position corresponding to the memory element body 2 and the piezoelectric element 37 of the substrate 36 immediately below. The gap 46 facilitates the deformation of the memory element stacked body 7 based on the deformation of the piezoelectric body 11 of the piezoelectric element 37.
Other configurations including the memory element body 2, the piezoelectric element 37, and the like are the same as those described in the fifth embodiment. Therefore, in FIG. Omitted.

According to the memory element 45 according to the sixth embodiment, the spin injection current can be reduced by applying the spin injection current to the memory element stack 7 while applying a voltage to the piezoelectric element 37, as described above. Can do. Therefore, it is possible to provide a non-volatile memory that can be recorded with a small spin injection current while maintaining stable recording and that can be used practically.
Further, in the present embodiment, since the gap 46 is provided in the portion immediately below the memory element body 2 and the piezoelectric element 37 of the substrate 36, the recording layer 5 can be easily deformed based on the deformation of the piezoelectric element 37. .
[Modification]
The above-described configuration in which the cavity 46 is provided in the substrate can also be applied to the configurations of the first to fourth embodiments.

<8. Seventh Embodiment>
[Schematic configuration example of memory element]
FIG. 11 shows a schematic configuration of the seventh embodiment of the memory element according to the present invention. As in the fifth embodiment, the memory element 48 according to the seventh embodiment is configured by stacking a piezoelectric element 37 and a memory element body on a substrate 36.

In the present embodiment, in particular, a highly elastic member 49 having higher elasticity than the substrate 36 is interposed between the substrate 36 and the piezoelectric element 37. The highly elastic member 49 facilitates the deformation of the memory element stack 7 based on the deformation of the piezoelectric body 11 of the piezoelectric element 37. As the highly elastic member 49, for example, a rubber member or the like can be used.
Other configurations including the memory element body 2 and the piezoelectric element 37 are the same as those described in the fifth embodiment. Therefore, in FIG. 11, portions corresponding to those in FIG. Omitted.

According to the memory element 48 according to the seventh embodiment, the spin injection current can be reduced by flowing the spin injection current through the memory element stacked body 7 while applying a voltage to the piezoelectric element 37 as described above. Can do. Therefore, it is possible to provide a non-volatile memory that can be recorded with a small spin injection current while maintaining stable recording and that can be used practically.
Further, in the present embodiment, since the highly elastic member 49 is provided between the substrate 36 and the piezoelectric element 37, the recording layer 5 can be easily deformed based on the deformation of the piezoelectric element 37.
[Modification]
The structure provided with the above-described highly elastic member 49 can also be applied to the structures of the first to fourth embodiments.

<9. Eighth Embodiment>
[Schematic configuration example of memory element]
FIG. 12 shows a schematic configuration of the eighth embodiment of the memory element according to the present invention. A memory element 51 according to the eighth embodiment includes a memory element body 55 including a memory element stacked body 54 and upper and lower electrodes 8 and 9 formed on the front and back surfaces of the memory element stacked body 54 on a substrate 52. Formed and configured. The memory element laminate 54 is formed by laminating a reference layer (magnetic layer) 4, a recording layer (magnetic layer) 5, and a nonmagnetic layer 53 provided between the reference layer 4 and the recording layer 5. . As described in the above embodiment, the recording layer 5 and the reference layer 4 are formed by selecting the plane magnetization film or the main direct magnetization film, and the magnetostriction polarity.

  In this embodiment, in particular, the nonmagnetic layer 53 is formed of a piezoelectric film. This piezoelectric film is configured so that the film thickness changes due to the piezoelectric effect. The thickness of the piezoelectric film is selected so as to function as a tunnel barrier film through which a spin injection current flows. A recording voltage source 56 for flowing a spin injection current is connected between the upper electrode 8 and the lower electrode 9 of the memory element body 2.

  Next, the operation of the memory element 51 according to the eighth embodiment will be described. When information is recorded, recording is performed by a spin injection current flowing from the recording voltage source 56 to the recording layer 5 of the memory element body 2 through the upper electrode 8 and the lower electrode 9. At this time, when an electric field is generated in the piezoelectric film constituting the nonmagnetic layer 53, the nonmagnetic layer 53 is deformed in the film thickness direction due to the piezoelectric effect. The deformation of the nonmagnetic layer 53 propagates to the recording layer 5 to deform the recording layer 5. The magnetic anisotropy of the recording layer 5 is weakened by the inverse magnetostriction effect, the coercive force is lowered, and the spin injection current is reduced. .

  According to the memory element 51 according to the eighth embodiment, the spin injection current can be reduced by forming the nonmagnetic layer 53 with a piezoelectric film. Therefore, it is possible to provide a non-volatile memory that can be recorded with a small spin injection current while maintaining stable recording and that can be used practically. Further, by forming the nonmagnetic layer 53 with a piezoelectric body, the configuration of the entire memory element can be simplified.

<10. Ninth Embodiment>
[Schematic configuration example of memory element]
13A and 13B show a schematic configuration of the ninth embodiment of the memory element according to the present invention. A memory element 57 according to the ninth embodiment illustrated in FIG. 13A includes the memory element body 2 and the piezoelectric body 11. As described above, the memory element body 2 includes a reference layer (magnetic layer) 4, a recording layer (magnetic layer) 5, and a nonmagnetic layer 6 provided between the reference layer 4 and the recording layer 5. The memory element stack 7, and the upper electrode 8 and the lower electrode 9 formed on the front and back surfaces of the memory element stack 7. The recording layer 5 and the reference layer 4 can be formed of a perpendicular magnetization film having a positive or negative magnetostriction.

  On the other hand, the piezoelectric body 11 is formed between the reference layer 4 and the nonmagnetic layer 6. The piezoelectric body 11 is formed of a piezoelectric body that deforms in the thickness direction. For example, the piezoelectric body 11 can be formed of a piezoelectric body that extends and deforms in the thickness direction, or a piezoelectric body that compressively deforms in the thickness direction.

  Further, a recording voltage source 22 is connected between the upper electrode 8 and the lower electrode 9. The recording voltage source 22 serves both as a spin injection current supply source that supplies a spin injection current to the memory element stack 7 and a voltage supply source that applies an electric field to the piezoelectric body 11.

  The memory element 58 according to the ninth embodiment shown in FIG. 13B is configured in the same manner as in FIG. 13A except that the piezoelectric body 11 is formed between the nonmagnetic layer 6 and the recording layer 5.

  Next, operations of the memory elements 57 and 58 according to the ninth embodiment will be described. At the time of recording information, a spin injection current flows from the recording voltage source 22 to the recording layer 5 through the upper electrode 8 and the lower electrode 9 of the memory element body 2. At this time, an electric field is simultaneously applied to the piezoelectric body 11 (FIG. 13A) between the reference layer 4 and the nonmagnetic layer 6 or the piezoelectric body 11 (FIG. 13B) between the nonmagnetic layer 6 and the recording layer 5. For example, when the recording layer 5 is formed of a perpendicularly magnetized film having a positive magnetostriction and the piezoelectric body 11 is deformed so as to extend in the thickness direction by the above-described electric field, a compressive stress in the thickness direction is generated in the recording layer 5 and the inverse magnetostriction is generated. As a result, the magnetic anisotropy is weakened, and the coercive force of the recording layer 5 is reduced.

  On the contrary, for example, when the recording layer 5 is formed of a perpendicular magnetization film having a negative magnetostriction and the piezoelectric body 11 is deformed so as to shrink in the thickness direction by the electric field, a tensile stress in the thickness direction is generated in the recording layer 5. The magnetic anisotropy is weakened by the inverse magnetostriction effect, and the coercive force of the recording layer 5 is lowered. In either case, the spin injection current can be reduced by the reduction of the coercive force of the recording layer 5.

  According to the memory elements 57 and 58 according to the ninth embodiment, the spin injection current can be reduced by applying the spin injection current to the memory element stack 7 while applying an electric field to the piezoelectric body 11. Therefore, it is possible to provide a non-volatile memory which can be recorded with a small spin injection current while maintaining recording stably and which can be used practically.

<11. Verification of the effect of the memory element of the present invention>
First, FIG. 14 shows a method for manufacturing a measurement sample (memory element) for verifying the effect of the memory element of the present invention. As shown in FIG. 14A, two grooves 62 are formed on the surface of a single crystal substrate 61 of BaTiO ₃ that is a piezoelectric material. The depth h of the groove 62 is about 100 nm, and the distance d between the grooves 62 is 100 nm.

  Next, as shown in FIG. 14B, copper (Cu) is filled in the two grooves 62 to flatten the surface, and a pair of copper electrodes 63 [63A, 63B] are formed. The pair of electrodes 63A and 63B and the piezoelectric body 61a sandwiched between the electrodes 63A and 63B constitute a piezoelectric element 60.

Next, as shown in FIG. 14C, an insulating layer 64 and a lower electrode 65 are formed on the surface of the single crystal substrate 61 including the piezoelectric element 60, and a memory element body 66 and an upper electrode 67 are further formed on the lower electrode 65. Is deposited. The memory element body 66 is formed corresponding to a region between the electrodes 63A and 63B in the groove 62. The insulating layer 64 is formed of a silicon oxide (SiO ₂ ) film having a thickness of 20 nm. The lower electrode 65 is formed of a Cu film having a thickness of 10 nm. The upper electrode 67 is formed of a Ti film having a thickness of 5 nm.

  As shown in FIG. 15, the memory element body 66 is formed as a so-called tunnel magnetoresistive element (MTJ element) in which layers are stacked. That is, from the bottom, a lower electrode 71 made of a Ta film having a thickness of 5 nm, an antiferromagnetic layer 72 made of a PtMn film having a thickness of 20 nm, a magnetic layer 73 made of a CoFe film having a thickness of 2 nm, and a nonmagnetic material made of a Ru film having a thickness of 0.8 nm. A magnetic layer (reference layer) 75 made of a layer 74 and a CoFeB film having a thickness of 2 nm is formed. The magnetization fixed layer 79 is constituted by the three layers of the magnetic layer 73, the nonmagnetic layer 74, and the magnetic layer 75. Further, a nonmagnetic layer (tunnel insulating layer) 76 made of a 0.8 nm thick MgO film, a recording layer (magnetic layer) 77 made of a 3 nm thick CoFeTaB film, and an upper electrode 78 made of a 5 nm thick Ta film are formed. . The memory element body 66 is formed in an elliptical shape having a major axis of 200 nm and a minor axis of 80 nm. The direction perpendicular to the paper surface of FIG. 14D (the depth direction of the paper surface) is the major axis direction. Each of the above magnetic layers is an in-plane magnetization film.

  Next, as shown in FIG. 14D, the side surfaces of the memory element body 66 and the upper electrode 67 and the surface of the lower electrode 65 are covered with an insulating member 81, and a terminal 82 connected to a part of the lower electrode 65 and the upper electrode 67. A terminal 83 connected to is formed. Although not shown, terminals connected to the electrodes 63A and 63B of the piezoelectric element 60 are also formed. In this manner, the memory element 84 as a sample is manufactured by integrating the target piezoelectric element 60 and the memory element body (MTJ element) 66.

  Measurement was performed using the memory element 84. FIG. 16 shows the relationship between the voltage (Va) applied to the piezoelectric element 60 and the coercive force (Hc) of the recording layer 77 of the memory element body (MTJ element) 66. When the voltage Va applied to the piezoelectric element 60 is increased in absolute value, the coercive force of the recording layer 77 of the memory element body (MTJ element) 66 is lowered, and the change of the piezoelectric element 60 (and hence the piezoelectric body 61a) is changed. It can be confirmed that it acts on the MTJ element 66.

  FIG. 17 shows a reversal error rate when spin injection magnetization reversal is performed by applying different voltages to the piezoelectric elements 60 and applying a 100 ns pulse width pulse voltage (Vp) to the memory element body (MTJ element) 66. And the applied pulse voltage (Vp). In this measurement, when a voltage is not applied to the piezoelectric element 60 (Va = 0V), a DC voltage of 10V (Va = 10V) is applied, and a high frequency voltage (Va = rf) with an amplitude width of 3V and a frequency of 2.5 GHz. 3Vpp) is applied.

  When a direct current or high frequency voltage is applied to the piezoelectric element 60, that is, the piezoelectric body 61a, the inversion error rate decreases at a low pulse voltage (Vp), and the effect of the memory element of the present invention can be confirmed.

  Next, the effect of the memory element of the present invention on the perpendicular magnetization film will be verified. FIG. 18 shows a sample. The sample 86 is configured by arranging a plurality of laminated bodies 90 of perpendicular magnetization films 88 and piezoelectric bodies 89 on the lower electrode 8 and forming a common upper electrode 91 over each laminated body 90. The lower electrode 87 is formed of an Au film having a thickness of 20 nm. The upper electrode 91 is formed of a transparent electrode. The perpendicular magnetization film 88 is formed of a laminated film in which a Co film having a thickness of 0.5 nm and a Ni film having a thickness of 0.5 nm are continuously laminated for five periods. The piezoelectric body 89 is formed of a ZnO film having a thickness of 10 nm. A space where the stacked body 90 of the perpendicular magnetization film 88 and the piezoelectric body 89 between the lower electrode 87 and the upper electrode 91 is not formed is filled with an insulating film 92 such as a silicon oxide (SiO 2) film. The one laminate 90 is formed in a pattern having a diameter of 100 nm.

  The aggregate of the laminate 90 was measured by the magneto-optical effect. FIG. 19 shows the relationship between the voltage applied to the piezoelectric body 89 and the coercivity of the perpendicular magnetization film 88. Also in the perpendicular magnetization film 88, when the voltage Va applied to the piezoelectric body 89 is increased in absolute value, the coercive force of the perpendicular magnetization film 88 is lowered, and the effect of the present invention can be confirmed.

  Furthermore, the effect of the present invention is verified with a simpler configuration. Although not shown, the sample is configured by forming an elliptical MTJ element as viewed from above and filling a portion in contact with the MTJ element with a piezoelectric material. An in-plane magnetic film was used for the sample MTJ element. During recording, the piezoelectric material is deformed by the electric field generated at the end of the tunnel barrier layer (nonmagnetic layer) of the sample MTJ element, and the reversal current (spin injection current) is reduced by the deformation affecting the recording layer. The effect was measured. Table 1 shows the measurement result of the reversal current Jco when the piezoelectric material to be filled is changed. Table 1 shows an MTJ element using an AlN film, a BaTiO3 film, and a LiNbO3 film as a piezoelectric material in comparison with an MTJ element using amorphous silicon oxide (SiO2) as a filling material.

  As can be seen from Table 1, in the MTJ element using any piezoelectric material as the filling material, the reversal current Jco is reduced compared to the MTJ element using an amorphous silicon oxide film as the filling material. It is confirmed.

  1. Memory element 2. Memory element body 3. Piezoelectric element 4. Reference layer 5. Recording layer 6. Non-magnetic layer 7. Memory element stack 8, 8. Upper part Electrode, 9 ... Lower electrode, 11 ... Piezoelectric body, 12, 13 ... Electrode, 15 ... Substrate

Claims (11)

A reference layer with a determined magnetization direction;
A recording layer whose magnetization direction changes depending on the recorded information;
A non-magnetic layer provided between the reference layer and the recording layer, and a memory element stack for recording information on the recording layer with a spin injection current;
A piezoelectric body provided on a side portion of the memory element stack;
A memory element comprising: means for applying an electric field to the piezoelectric body. The recording layer and the reference layer are planar magnetoresistive films having a positive magnetostriction, and are formed in a shape having a major axis and a minor axis orthogonal to each other,
The memory element according to claim 1, wherein the piezoelectric body is deformed so as to apply a compressive stress in a major axis direction or a tensile stress in a minor axis direction with respect to the recording layer by the electric field. The recording layer and the reference layer are planar magnetic films having negative magnetostriction, and are formed in a shape having a major axis and a minor axis orthogonal to each other,
The memory element according to claim 1, wherein the piezoelectric body is deformed by the electric field so as to apply a tensile stress in a major axis direction or a compressive stress in a minor axis direction with respect to the recording layer. The memory element according to claim 2, wherein the memory element stack and the piezoelectric body having a pair of electrodes are disposed on a substrate. A pair of the piezoelectric bodies are disposed on both sides of the memory element stack,
4. The memory element according to claim 2, wherein means for applying an electric field to the piezoelectric body and means for applying a spin injection current during recording to the memory element stack are shared. The recording layer and the reference layer are perpendicular magnetization films having negative magnetostriction, and are formed in a circular shape,
The memory element according to claim 1, wherein the piezoelectric body is deformed by the electric field so as to apply a compressive stress to the recording layer from the outside. The recording layer and the reference layer are perpendicular magnetization films having a positive magnetostriction, and are formed in a circular shape,
The memory element according to claim 1, wherein the piezoelectric body is deformed by the electric field so as to apply an outward tensile stress to the recording layer. The piezoelectric body is formed in a cylindrical shape surrounding the outside of the memory element stack,
A conductive film electrically connected to the lower electrode of the memory element stack is formed outside the piezoelectric body,
The memory element according to claim 6, wherein means for applying an electric field to the piezoelectric body and means for applying a spin injection current during recording to the memory element stack are shared. The memory element according to claim 1, wherein a piezoelectric body that deforms in a thickness direction is formed at an end portion between the reference layer and the recording layer, leaving a central portion of the nonmagnetic layer. The memory element according to claim 9, wherein the recording layer is formed of two laminated magnetic films having different magnetostrictive polarities. The voltage applied to the piezoelectric body is a high-frequency voltage,
The memory element according to claim 1, wherein a frequency of the high-frequency voltage is 1 GHz or more and 10 GHz or less.

Images