JP2007281247A - Spin memory - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a spin memory having thermal fluctuation resistance, low power consumption, low current in writing performance, and high reliability. <P>SOLUTION: The spin memory is provided with first and second conducting lines 13 and BLu, a magnetoresistance effect element MTJ arranged between one end of the first conducting line 13 and the second conducting line BLu, a switch element SW connected to the other end of the first conducting line 13, and a driver/sinker making spin implantation current Is for inverting magnetization by a spin torque flow to the magnetoresistance effect element MTJ through the first and second conducting lines 13 and BLu. The magnetoresistance effect element MTJ has a magnetic recording layer whose magnetization direction is variable and a magnetic fastening layer whose magnetization direction is fastened. An angle θ is 0°<θ≤45° between a magnetization easy axis of the magnetic recording layer and a long axis of the first conducting line 13. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a spin memory that uses a magneto-resistive effect.

  While the magnetoresistive effect is used in a magnetic head, a magnetic sensor, or the like, application to a spin memory represented by a magnetic random access memory has been studied.

  For example, in a magnetic random access memory, a memory cell is a magnetoresistive element that stores data according to the magnetization state of a magnetic layer and reads data by the magnetoresistive effect. Magnetic random access memory is attracting attention as a high-speed, non-volatile RAM, but there are many problems that must be solved for practical use.

  One of them is a reduction in write current. In the writing method in which the magnetization reversal is performed using the magnetic field generated by the write current, there is a problem that the value of the write current necessary for the magnetization reversal increases as the memory cell is shrunk.

  A technique devised therefor is a writing method by spin injection magnetization reversal (see, for example, Patent Document 1).

  In this method, spin-polarized electrons are injected into the magnetic layer, and magnetization reversal is performed by torque generated between the spin-polarized electrons and the electrons in the magnetic layer. The spin injection current value necessary for magnetization reversal is small.

  However, in the writing method by spin injection magnetization reversal, the breakdown of the tunnel insulating film of the magnetoresistive effect element due to the spin injection current becomes a problem. That is, in order to maintain the reliability of the magnetoresistive effect element, it is essential to reduce the current density of the spin injection current necessary for the magnetization reversal.

The ultimate goal is to maintain low power consumption and high reliability while maintaining low power consumption and high reliability even when memory cells are miniaturized to ensure scalability. Development of technology that can be reversed is desired.
US Pat. No. 6,256,223

  An example of the present invention provides a spin memory that has thermal fluctuation resistance even when a memory cell is miniaturized, and can perform magnetization reversal at a low current density while maintaining low power consumption and high reliability.

  A spin memory according to an example of the present invention includes first and second conductive lines, a first magnetoresistive element disposed between one end of the first conductive line and the second conductive line, and the first conductive line. A switching element connected to the other end, and a driver / sinker for passing a spin injection current for magnetization reversal by spin torque to the first magnetoresistive element via the first and second conductive lines, The resistance effect element includes a magnetic recording layer having a variable magnetization direction and a first magnetic fixed layer to which the magnetization direction is fixed, and an angle formed between an easy axis of magnetization of the magnetic recording layer and a long axis of the first conductive line. θ is 0 ° <θ ≦ 45 °.

  A spin memory according to an example of the present invention includes a first conductive line, a second conductive line, a magnetoresistive effect element disposed between one end of the first conductive line and the second conductive line, and the other end of the first conductive line. A switching element connected to, a driver / sinker for passing a spin injection current for magnetization reversal by spin torque to the magnetoresistive effect element via the first and second conductive lines, and a magnetic field for assisting magnetization reversal by spin torque The magnetoresistive effect element includes a magnetic recording layer having a variable magnetization direction and a magnetic pinned layer to which the magnetization direction is fixed, and the magnetization of the magnetic recording layer is provided. The angle θ formed by the easy axis and the long axis of the first conductive line is 0 ° <θ ≦ 45 °.

  According to the example of the present invention, even if a memory cell is miniaturized, a spin memory that is resistant to thermal fluctuation, can maintain magnetization with low current density while maintaining low power consumption and high reliability is realized. it can.

  The best mode for carrying out an example of the present invention will be described below in detail with reference to the drawings.

1. Overview
The spin memory according to the example of the present invention is premised on a writing method in which magnetization reversal is performed by spin torque and a magnetic field is used as an assist for magnetization reversal. In the layout. Specifically, the angle θ formed between the axis of easy magnetization of the magnetoresistive effect element and the long axis of the conductive wire is set to 0 ° <θ ≦ 45 °.

  This conductive line is a conductive line in which a magnetoresistive effect element is disposed at one end and a switch element is connected to the other end. For example, a lower electrode in direct contact with the magnetoresistive effect element corresponds to this conductive line. The switch element has a function of selecting a magnetoresistive effect element at the time of reading / writing, and is disposed, for example, below the magnetoresistive effect element.

  According to such a layout, when performing magnetization reversal by spin torque, it becomes possible to maximize the assist effect of magnetization reversal by a magnetic field, so that the current density of the spin injection current can be drastically reduced.

  The magnetoresistive element preferably has a SAF (synthetic anti-ferromagnetic) -free layer structure. The magnetic field may be generated using a spin injection current for generating spin-polarized electrons, or may be generated by an assist current different from the spin injection current.

  The specific write sequence and the direction of the magnetoresistive effect element necessary for exhibiting the maximum assist effect will be described in detail in the embodiment.

2. Reference example
(1) Magnetoresistive Effect Element FIG. 1 shows a structural example of a magnetoresistive effect element used as a memory cell of a spin memory.

  FIG. 1A shows the basic structure of the magnetoresistive element.

A base layer (Ru) is disposed on the electrode M1, and a magnetoresistive element is disposed on the base layer. Magnetoresistive element, the free layer of the magnetic recording layer (Co ₉₀ Fe _10), a pinned (pinned) layer serving as a magnetic pinned layer (Co ₉₀ Fe _10), and, from the tunnel barrier layer between them (MgO) Composed. The magnetization direction of the pinned layer is fixed by the antiferromagnetic layer (IrMn). A cap layer (Ru / Ta) as a protective layer is disposed on the antiferromagnetic layer.

  FIG. 2B shows a magnetoresistive effect element having a SAF-free layer structure.

A base layer (Ru) is disposed on the electrode M1, and a magnetoresistive element is disposed on the base layer. The magnetoresistive effect element includes a free layer (Co ₉₀ Fe ₁₀ / Ru / Co ₉₀ Fe ₁₀ ) as a magnetic recording layer, a pinned layer (Co ₉₀ Fe ₁₀ ) as a magnetic pinned layer, and a gap between them. It is composed of a tunnel barrier layer (MgO).

The free layer is composed of two magnetic bodies (Co ₉₀ Fe ₁₀ ) and a non-magnetic body (Ru) between them, and the two magnetic bodies are antiferromagnetically coupled to each other via the non-magnetic body. .

  The magnetization direction of the pinned layer is fixed by the antiferromagnetic layer (IrMn). A cap layer (Ru / Ta) as a protective layer is disposed on the antiferromagnetic layer.

When the SAF-free layer structure is adopted, as shown in FIG. 2, the magnetic interaction (strength of antiferromagnetic coupling) J _EX generated between two magnetic bodies is particularly
J _EX ≧ 0.52 erg / cm ²
In this case, the thermal disturbance resistance is improved, and scalability is ensured.

(2) Memory Cell Structure FIGS. 3 and 4 show examples of the memory cell structure.

  An element isolation insulating layer 12 having an STI (shallow trench isolation) structure is disposed in the semiconductor substrate 11. In the element region surrounded by the element isolation insulating layer 12, for example, a MISFET (including a MOSFET) is disposed as the switch element SW. One end of the switch element SW is connected to the lower bit line BLd as a conductive line through the contact part A. The lower bit line BLd extends in the column direction, for example.

  The conductive wire 13 has a yoke structure and includes a conductor 13a and a soft magnetic body 13b that covers the lower surface and side surfaces of the conductor 13a. The magnetoresistive element MTJ is disposed at one end of the conductive wire 13. The other end of the conductive line 13 is connected to the other end of the switch element SW via the contact part B.

  The conductive line 13 extends in the column direction in the example of FIG. 3, and extends in an oblique direction between the column direction and the row direction perpendicular to the column direction in the example of FIG.

  An upper bit line BLu as a conductive line is disposed on the magnetoresistive element MTJ via a contact part 14 such as a via plug or a metal hard mask. The upper bit line BLu extends, for example, in the column direction.

Here, the magnetoresistive effect element MTJ is laid out as follows.
The axis of easy magnetization of the magnetoresistive element MTJ is aligned with the longitudinal direction of the conductive wire 13. The axis of hard magnetization of the magnetoresistive element MTJ is perpendicular to the easy axis of magnetization.

  The spin injection current Is is given to the magnetoresistive effect element MTJ through the conductive line 13, the upper bit line BLu, and the lower bit line BLd. In this example, the direction of the spin injection current Is flowing in the conductive line 13 and the direction of the spin injection current Is flowing in the upper bit line BLu are different by 90 ° or more (180 ° in the example of FIG. 3). The direction of the spin injection current Is flowing through BLu may be changed to be 90 ° or less (the same direction in the example of FIG. 3).

  According to the layout of the magnetoresistive element MTJ described above, in both the examples of FIGS. 3 and 4, the magnetic field lines of the magnetic field (assist magnetic field) generated by the spin injection current Is flowing in the conductive line 13 are The MTJ extends in the hard axis direction. Further, the conductive wire 13 has a yoke structure so that the magnetic force lines can be easily converged.

  Therefore, at the time of spin injection writing, the magnetic field in the hard axis direction acts efficiently on the magnetoresistive element MTJ, and the magnetization reversal is assisted.

  FIG. 5 shows the reduction of the spin inversion energy barrier by the assist magnetic field. From the figure, it can be seen that the larger the value of the assist magnetic field Hy in the hard axis direction, the lower the spin inversion energy barrier.

  When the spin injection writing is executed for the magnetoresistive effect element having the astroid curve of FIG. 6, the current density of the spin injection current necessary for the magnetization reversal is as shown in FIG.

  FIG. 8 shows the relationship between the current density of the spin injection current and the resistance value of the magnetoresistive effect element.

  The sample is a magnetoresistive element whose free layer is a single layer (CoFeB: 2 nm), IrMn: 10 nm / CoFe: 3 nm / Ru: 0.9 nm / CoFeB: 4 nm / MgO: 1 nm / CoFeB: 2 nm. When plotting the relationship between the current density of the spin injection current and the resistance value of the magnetoresistive effect element, the strength of the magnetic field in the hard axis direction (assist magnetic field) is plotted as a parameter for this sample, as shown in FIG. Become.

  As is clear from the figure, as the assist magnetic field Hhard increases from 0 → 20 → 25 [Oe], the current density of the spin injection current necessary for magnetization reversal is reduced.

  Therefore, it is examined whether this can be said for a magnetoresistive effect element having a SAF-free layer structure.

FIG. 9 and FIG. 10 show an example of a memory cell structure including a magnetoresistive effect element having a SAF-free layer structure.
9 and 10 correspond to FIGS. 3 and 4.

  When the SAF-free layer structure is adopted, as shown in FIG. 11, the astroid curve is separated from the hard axis of magnetization.

  In this case, the current density of the spin injection current necessary for the magnetization reversal is hardly reduced by the magnetic field (assist magnetic field) Hhard in the hard axis direction.

  The cause is considered to be the difference between the writing principle by spin injection and the writing principle by magnetic field. In writing by spin injection, it is preferable that the difference between the thicknesses of the two magnetic bodies constituting the SAF-free layer is small or zero (the thicknesses of the two magnetic bodies are the same).

However, in writing by a magnetic field, if the difference in thickness between the two magnetic bodies constituting the SAF-free layer is small, it is difficult to perform magnetization reversal. In particular, when only the magnetic field Hhard in the direction of the hard axis exists and the thickness of the two magnetic bodies is the same, the direction of the moment of magnetic spin is more inclined due to the magnetic interaction J _EX that occurs between the two magnetic bodies. It becomes difficult.

  When assuming a writing method by spin injection magnetization reversal, it is preferable to set the difference Δt between the thicknesses of two magnetic bodies constituting the SAF-free layer within a range of 0 nm ≦ Δt ≦ 2 nm. This is because the spin injection efficiency decreases when the difference Δt in thickness between the two magnetic bodies exceeds 2 nm.

  In this case, as shown in FIG. 12, even if the assist magnetic field Hhard is gradually increased from 0 → 20 → 25 [Oe], the current density of the spin injection current necessary for magnetization reversal is hardly reduced.

  Therefore, for the magnetoresistive effect element having the SAF-free layer structure, the purpose of reducing the current density of the spin injection current cannot be achieved simply by providing an assist magnetic field in the hard axis direction.

3. Embodiment
In the following embodiment, an example of a technique for maximizing the assist effect of magnetization reversal by an assist magnetic field will be described, particularly for a magnetoresistive effect element having a SAF-free layer structure.

  In addition, since the effect of exhibiting the maximum assist effect is not limited to the SAF-free layer structure but also occurs in a structure in which the free layer is a single layer (single layer free), this will also be described later.

(1) First embodiment
The first embodiment relates to a layout of a magnetoresistive effect element.

13 and 14 show layouts according to the first embodiment.
13 corresponds to FIG. 9, and FIG. 14 corresponds to FIG.

  The magnetoresistive element MTJ has a SAF-free layer structure and is disposed on one end of the conductive wire (lower electrode) 13. The conductive line 13 extends in the column direction in the example of FIG. 13, and extends in an oblique direction between the row direction and the column direction orthogonal to each other in the example of FIG.

  The other end of the conductive wire 13 is connected to the switch element SW as shown in FIGS. The upper bit line BLu extends in the column direction.

  An angle θ formed by the easy axis of magnetization of the magnetoresistive element MTJ and the long axis of the conductive wire 13 is set to 0 ° <θ ≦ 45 °.

  According to such a layout, when performing magnetization reversal by spin torque, it becomes possible to maximize the assist effect of magnetization reversal by a magnetic field, so that the current density of the spin injection current can be drastically reduced.

FIG. 15 shows an astroid curve when the angle θ between the easy axis of magnetization of the magnetoresistive effect element and the long axis of the conductive wire is 45 °.
In the simplest case, that is, when other conditions are not taken into account, when the angle θ between the easy axis of the magnetoresistive element and the long axis of the conductive wire is 45 °, the shape of the astroid curve is the most. At this time, the assist effect of magnetization reversal by the assist magnetic field Hhard is maximized.

  Incidentally, the strength (efficiency) of the spin torque depends on the MR ratio (magneto-resistive ratio) as shown in FIG.

  When the MR ratio is about 50% or more, the spin torque strength is a function of the spin relative angle φ between the pinned layer and the free layer, and takes a maximum value within a certain range. Therefore, when the SAF-free layer structure is used, the angle θ is set to a value that maximizes the strength of the spin torque based on the MR ratio.

  When the MR ratio is less than about 50%, the angle θ formed between the easy axis of the magnetoresistive element and the long axis of the conductive wire is 45 ° based on the shape of the astroid curve as described above. To do.

  Therefore, the angle θ formed by the magnetization easy axis of the magnetoresistive effect element and the long axis of the conductive wire is set to a value within the range of 0 ° <θ ≦ 45 °.

(2) Second embodiment
The second embodiment relates to the structure of the magnetoresistive effect element.

  FIGS. 17A and 17B show a first example of a magnetoresistive element.

  FIG. 4A shows a bottom pin type.

  An underlying layer is formed on the conductive line (lower electrode) M1, and an antiferromagnetic layer as a pinned layer is formed on the underlying layer. A ferromagnetic layer as a pinned layer is formed on the antiferromagnetic layer, and a SAF-free layer is formed on the pinned layer via a tunnel barrier layer.

The SAF-free layer is composed of two ferromagnetic layers and a nonmagnetic layer between them, and the strength J _EX of magnetic interaction (antiferromagnetic coupling) generated between the two ferromagnetic layers is: Set to 0.52 erg / cm ² or higher.

When the value of the magnetic interaction strength J _EX is large, the thermal stability of the magnetoresistive effect element is improved and the magnetization reversal can be performed coherently.

  A cap layer as a protective layer is formed on the SAF-free layer.

  FIG. 4B shows a top pin type.

A base layer is formed on the conductive line (lower electrode) M1, and a SAF-free layer is formed on the base layer. The SAF-free layer is composed of two ferromagnetic layers and a nonmagnetic layer between them, and the strength J _EX of magnetic interaction (antiferromagnetic coupling) generated between the two ferromagnetic layers is: Set to 0.52 erg / cm ² or higher.

  A ferromagnetic layer as a pinned layer is formed on the SAF-free layer via a tunnel barrier layer, and an antiferromagnetic layer as a pinned layer is formed on the pinned layer. A cap layer as a protective layer is formed on the antiferromagnetic layer.

  18 and 19 show a second example of the magnetoresistive effect element.

  These magnetoresistive elements are characterized in that the pinned layers are formed above and below the free layer, and the electron spin reflection function is added above and below the free layer to improve the magnetization reversal efficiency.

  FIG. 18 shows a bottom pin type.

  An underlying layer is formed on the conductive line (lower electrode) M1, and an antiferromagnetic layer as a pinned layer is formed on the underlying layer. A ferromagnetic layer as a pinned layer is formed on the antiferromagnetic layer, and a SAF-free layer is formed on the pinned layer via a tunnel barrier layer.

The SAF-free layer is composed of two ferromagnetic layers and a nonmagnetic layer between them, and the strength J _EX of magnetic interaction (antiferromagnetic coupling) generated between the two ferromagnetic layers is: Set to 0.52 erg / cm ² or higher.

  A pinned layer is formed on the SAF-free layer via a nonmagnetic layer. The nonmagnetic layer is composed of a dielectric layer thinner than the tunnel barrier layer and ruthenium (Ru). The pinned layer is composed of two ferromagnetic layers and a nonmagnetic layer between them. The magnetic interaction generated between the two ferromagnetic layers constituting the pinned layer may be antiferromagnetic coupling or ferromagnetic coupling.

  An antiferromagnetic layer as a pinned layer is formed on the pinned layer, and a cap layer as a protective layer is formed on the antiferromagnetic layer.

  FIG. 19 shows a top pin type.

  An underlying layer is formed on the conductive line (lower electrode) M1, and an antiferromagnetic layer as a pinned layer is formed on the underlying layer. A ferromagnetic layer as a pinned layer is formed on the antiferromagnetic layer, and a SAF-free layer is formed on the pinned layer via a nonmagnetic layer. The nonmagnetic layer is composed of ruthenium (Ru) and a dielectric layer thinner than the tunnel barrier layer.

The SAF-free layer is composed of two ferromagnetic layers and a nonmagnetic layer between them, and the strength J _EX of magnetic interaction (antiferromagnetic coupling) generated between the two ferromagnetic layers is: Set to 0.52 erg / cm ² or higher.

  A pinned layer is formed on the SAF-free layer via a tunnel barrier layer. The pinned layer is composed of two ferromagnetic layers and a nonmagnetic layer between them. The magnetic interaction generated between the two ferromagnetic layers constituting the pinned layer may be antiferromagnetic coupling or ferromagnetic coupling.

  An antiferromagnetic layer as a pinned layer is formed on the pinned layer, and a cap layer as a protective layer is formed on the antiferromagnetic layer.

  According to the magnetoresistive effect element of the second example, spin torque is generated above and below the free layer by the spin reflection layer, so that the magnetization reversal efficiency is improved and it is possible to contribute to the reduction of the current density of the spin injection current.

  When the nonmagnetic layer as the spin reflection layer is made of Ru, the magnetization directions of the two pinned layers (in the case of SAF coupling, the magnetization directions of the magnetic layers on the tunnel barrier layer side) are reversed. The orientation is preferred.

  In addition, when the nonmagnetic layer as the spin reflection layer is composed of one of Cu, Ag, and Au, the magnetization directions of the two pinned layers (in the case of SAF coupling, the tunnel barrier layer side) It is preferable that the magnetization directions of the magnetic layers be the same.

  20 and 21 show a third example of the magnetoresistive effect element.

  Similar to the second example, these magnetoresistive elements are also characterized in that pinned layers are formed above and below the free layer.

  FIG. 20 shows a bottom pin type.

  An underlying layer is formed on the conductive line (lower electrode) M1, and an antiferromagnetic layer as a pinned layer is formed on the underlying layer. A ferromagnetic layer as a pinned layer is formed on the antiferromagnetic layer, and a SAF-free layer is formed on the pinned layer via a tunnel barrier layer.

The SAF-free layer is composed of two ferromagnetic layers and a nonmagnetic layer between them, and the strength J _EX of magnetic interaction (antiferromagnetic coupling) generated between the two ferromagnetic layers is: Set to 0.52 erg / cm ² or higher.

  A pinned layer is formed on the SAF-free layer via a nonmagnetic layer. The nonmagnetic layer includes a dielectric layer thinner than the tunnel barrier layer and one material selected from the group consisting of copper (Cu), silver (Ag), and gold (Au).

  An antiferromagnetic layer as a pinned layer is formed on the pinned layer, and a cap layer as a protective layer is formed on the antiferromagnetic layer.

  FIG. 21 shows a top pin type.

  An underlying layer is formed on the conductive line (lower electrode) M1, and an antiferromagnetic layer as a pinned layer is formed on the underlying layer. A ferromagnetic layer as a pinned layer is formed on the antiferromagnetic layer, and a SAF-free layer is formed on the pinned layer via a nonmagnetic layer. The nonmagnetic layer is composed of one material selected from the group consisting of copper (Cu), silver (Ag), and gold (Au), and a dielectric layer that is thinner than the tunnel barrier layer.

The SAF-free layer is composed of two ferromagnetic layers and a nonmagnetic layer between them, and the strength J _EX of magnetic interaction (antiferromagnetic coupling) generated between the two ferromagnetic layers is: Set to 0.52 erg / cm ² or higher.

  A pinned layer is formed on the SAF-free layer via a tunnel barrier layer. An antiferromagnetic layer as a pinned layer is formed on the pinned layer, and a cap layer as a protective layer is formed on the antiferromagnetic layer.

  Also in the magnetoresistive element of the third example, the spin reflection layer causes the spin torque to be generated above and below the free layer, so that the magnetization reversal efficiency can be improved and the current density of the spin injection current can be reduced.

  When the nonmagnetic layer as the spin reflection layer is composed of one of Cu, Ag, and Au, the magnetization directions of the two pinned layers (on the tunnel barrier layer side in the case of SAF coupling) It is preferable that the magnetization directions of the magnetic layers be the same.

  When the nonmagnetic layer as the spin reflection layer is made of Ru, the magnetization directions of the two pinned layers (in the case of SAF coupling, the magnetization direction of the magnetic layer on the tunnel barrier layer side) are reversed. The orientation is preferred.

(3) Third embodiment
The third embodiment relates to a memory cell array structure.

  FIG. 22 shows a memory cell array according to the third embodiment.

  The memory cell includes a magnetoresistive element MTJ and a switch element (for example, MISFET) SW connected in series.

  The word line WL extends in the row direction and is connected to the control terminal of the switch element SW. One end of the word line WL is connected to the word line driver / decoder 15.

  The upper bit line BLu extends in the column direction and is connected to the magnetoresistive element MTJ. One end of the upper bit line BLu is connected to the bit line driver / sinker decoder 16 via a switch element (for example, MISFET) ST1. On / off of the switch element ST1 is controlled by, for example, a write control signal W.

  The other end of the upper bit line BLu is connected to a sense amplifier S / A via a switch element (for example, MISFET) ST2. On / off of the switch element ST2 is controlled by, for example, column selection signals CSL1,... CSLn. The sense amplifier S / A is composed of, for example, a differential amplifier.

  The lower bit line BLd extends in the column direction and is connected to the switch element SW. One end of the lower bit line BLd is connected to the bit line driver / sinker decoder 17 via a switch element (for example, MISFET) ST3. On / off of the switch element ST3 is controlled by a write control signal W, for example.

  The other end of the lower bit line BLd is connected to a ground point via a switch element (for example, MISFET) ST4. On / off of the switch element ST4 is controlled by, for example, a read control signal R.

  FIG. 23 is an embodiment of the memory cell array of FIG.

  The magnetoresistive element MTJ is disposed between the conductive line (lower electrode) 13 and the upper bit line BLu. The angle θ formed by the easy axis of magnetization of the magnetoresistive element MTJ and the long axis of the conductive wire 13 is set to a value in the range of 0 ° <θ ≦ 45 °.

  The bit line driver / sinker decoder 16 includes a P-channel MISFET P1 and an N-channel MISFET N1 connected in series between power supply terminals Vdd and Vss.

  The bit line driver / sinker decoder 17 includes a P-channel MISFET P2 and an N-channel MISFET N2 connected in series between power supply terminals Vdd and Vss.

  At the time of writing, the write control signal W becomes “H”, and the read control signal R and all the column selection signals CSLi become “L”. Further, the level of the word line WL corresponding to the selected row becomes “H”, and the levels of the other word lines maintain “L”.

  When the control signals A and C are “L” and the control signals B and D are “H”, the spin injection current flows from the bit line driver / sinker decoder 16 toward the bit line driver / sinker decoder 17.

  When the control signals A and C are “H” and the control signals B and D are “L”, the spin injection current flows from the bit line driver / sinker decoder 17 toward the bit line driver / sinker decoder 16.

  At the time of reading, the read control signal R becomes “H” and the write control signal W becomes “L”. Further, the level of the word line WL corresponding to the selected row and the column selection signal CSLi corresponding to the selected column are set to “H”, and the level of other word lines and the column selection signal are set to “L”. maintain.

  For example, the read current flows from the sense amplifier S / A toward the ground point via the switch element ST4. Since the value of the read potential Vr changes according to the magnetization state of the magnetoresistive effect element MTJ, the data value is determined by comparing this with the reference potential Vref.

(4) Fourth embodiment
The fourth embodiment relates to a magnetization reversal mechanism.

FIG. 24 shows an example of a memory cell structure.
Since the magnetization reversal mechanism varies depending on various factors, here, the magnetization reversal mechanism will be described with particular attention to the structure (bottom pin type or top pin type) of the magnetoresistive effect element MTJ and the magnetization direction of the pinned layer. .

A. Bottom pin type (pinned layer facing right)
25 and 26 show a magnetization reversal mechanism for a bottom pin type (pinned layer rightward) magnetoresistive effect element.

  Here, to simplify the explanation, it is assumed that the easy axis of the free layer and the easy axis of the pinned layer are substantially in the same direction.

  The right direction of the pinned layer means that the magnetization of the pinned layer is closer to one end side (side where the magnetoresistive effect element MTJ is disposed) than the other end side (side to which the switch element SW is connected) of the conductive wire 13. The state that is. When the pinned layer has a SAF structure, the magnetization of the pinned layer means the magnetization of the magnetic material on the free layer side of the pinned layer.

  When the magnetoresistive effect element MTJ is a bottom pin type (pinned layer rightward), the magnetization easy axis of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is viewed from the upper surface (from the upper bit line side to the conductive line 13 From the state where it coincides with the long axis of the conductive wire (lower electrode) 13, it is tilted by an angle θ (0 <θ ≦ 45 °) by counterclockwise rotation.

  Then, when changing the magnetization state of the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, the spin injection current Is flows from one end of the conductive line 13 toward the other end as shown in FIG. Here, as described above, one end of the conductive wire 13 is an end portion on the side where the magnetoresistive effect element MTJ is disposed, and the other end is an end portion on the side where the switch element SW is connected. .

  In this case, the flow of spin-polarized electrons (spin flow) generated by the spin injection current Is is directed from the pinned layer to the free layer of the magnetoresistive effect element MTJ. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive effect element MTJ is changed from the antiparallel state to the parallel state.

  In order to change the magnetization state of the magnetoresistive effect element MTJ from the parallel state to the antiparallel state, as shown in FIG. 26, the spin injection current Is flows from the other end of the conductive wire 13 toward one end. Here, one end and the other end of the conductive wire 13 are as defined in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive element MTJ. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive element MTJ changes from the parallel state to the antiparallel state.

B. Bottom pin type (pinned layer left)
27 and 28 show a magnetization reversal mechanism for a bottom pin type (pinned layer leftward) magnetoresistive effect element.

  Here, to simplify the explanation, it is assumed that the easy axis of the free layer and the easy axis of the pinned layer are substantially in the same direction.

  The leftward direction of the pinned layer refers to the direction in which the magnetization of the pinned layer is closer to the other end side (side to which the switch element SW is connected) than to one end side (side where the magnetoresistive effect element MTJ is disposed) of the conductive wire 13. The state that is. When the pinned layer has a SAF structure, the magnetization of the pinned layer means the magnetization of the magnetic material on the free layer side of the pinned layer.

  When the magnetoresistive effect element MTJ is a bottom pin type (leftward of the pinned layer), the magnetization easy axis of the magnetic body on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is viewed from the upper surface (the conductive line 13 from the upper bit line side). From the state where it coincides with the long axis of the conductive wire (lower electrode) 13, it is tilted by an angle θ (0 <θ ≦ 45 °) by rotating clockwise.

  Then, when changing the magnetization state of the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, the spin injection current Is flows from one end of the conductive line 13 toward the other end as shown in FIG.

  In this case, the flow of spin-polarized electrons (spin flow) generated by the spin injection current Is is directed from the pinned layer to the free layer of the magnetoresistive effect element MTJ. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive effect element MTJ is changed from the antiparallel state to the parallel state.

  In order to change the magnetization state of the magnetoresistive effect element MTJ from the parallel state to the antiparallel state, the spin injection current Is flows from the other end of the conductive line 13 toward one end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive element MTJ. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive element MTJ changes from the parallel state to the antiparallel state.

C. Top pin type (pinned layer facing right)
29 and 30 show a magnetization reversal mechanism for a top pin type (pinned layer rightward) magnetoresistive effect element.

  It is assumed that the easy axis of the free layer and the easy axis of the pinned layer are oriented in substantially the same direction. The definition of the pinned layer facing right is the same as described above.

  When the magnetoresistive effect element MTJ is a top pin type (pinned layer rightward), the magnetization easy axis of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is viewed from the top surface (from the upper bit line side to the conductive line). From the state where the long axis of the conductive wire (lower electrode) 13 coincides with the conductive wire (lower electrode) 13, it is inclined clockwise by an angle θ (0 <θ ≦ 45 °).

  When the magnetization state of the magnetoresistive element MTJ is changed from the antiparallel state to the parallel state, the spin injection current Is flows from the other end of the conductive line 13 toward one end as shown in FIG. Here, one end and the other end of the conductive wire 13 are as defined in FIG.

  In this case, the flow of spin-polarized electrons (spin flow) generated by the spin injection current Is is directed from the pinned layer to the free layer of the magnetoresistive effect element MTJ. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive effect element MTJ is changed from the antiparallel state to the parallel state.

  Further, when the magnetization state of the magnetoresistive element MTJ is changed from the parallel state to the antiparallel state, the spin injection current Is flows from one end of the conductive line 13 toward the other end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive element MTJ. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive element MTJ changes from the parallel state to the antiparallel state.

C. Top pin type (pinned layer facing left)
31 and 32 show a magnetization reversal mechanism for a top pin type (pinned layer leftward) magnetoresistive effect element.

  It is assumed that the easy axis of the free layer and the easy axis of the pinned layer are oriented in substantially the same direction. The definition of the pinned layer facing left is the same as described above.

  When the magnetoresistive effect element MTJ is a top pin type (pinned layer leftward), the magnetization easy axis of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is viewed from the top surface (from the upper bit line side to the conductive line). From the state of matching the long axis of the conductive wire (lower electrode) 13, the counterclockwise tilt is made by an angle θ (0 <θ ≦ 45 °).

  Then, when changing the magnetization state of the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, the spin injection current Is flows from the other end of the conductive wire 13 toward one end as shown in FIG.

  In this case, the flow of spin-polarized electrons (spin flow) generated by the spin injection current Is is directed from the pinned layer to the free layer of the magnetoresistive effect element MTJ. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive effect element MTJ is changed from the antiparallel state to the parallel state.

  Further, when the magnetization state of the magnetoresistive element MTJ is changed from the parallel state to the antiparallel state, the spin injection current Is is caused to flow from one end of the conductive line 13 toward the other end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive element MTJ. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive effect element MTJ when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed at a small current density, and the magnetization state of the magnetoresistive element MTJ changes from the parallel state to the antiparallel state.

E. Summary
Thus, at the start of magnetization reversal, the direction of the magnetic field H generated by the spin injection current Is and the direction of the electron spin (magnetization direction) in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer. When the relative angle x is set to 90 ° <relative angle x ≦ 135 °, the assist effect can be maximized.

  In the present embodiment, the magnetic body having a large volume among the two magnetic bodies of the SAF-free layer is a magnetic body in contact with the tunnel barrier layer. However, the present invention is not limited to this.

  The difference in volume between the two magnetic bodies constituting the SAF-free layer may be considered as a difference in thickness between the two magnetic bodies when the area when viewed from above is equal.

  The magnetoresistive element MTJ may have a single layer free layer (single layer free) in addition to the SAF-free layer structure.

  Further, although it is assumed that the magnetoresistive element MTJ is disposed above the conductive line (lower electrode) for generating the assist magnetic field, it may be disposed below the conductive line.

  Of course, the bottom pin type and the top pin type include those having a spin reflection layer as shown in FIGS.

(5) Fifth embodiment
In the fifth embodiment, the relationship between the direction of tilting the magnetoresistive element (left rotation or right rotation) and the assist effect will be considered.

A. Bottom pin type (pinned layer facing right)
33 and 34 show a magnetization reversal sequence for a bottom pin type (pinned layer rightward) magnetoresistive effect element.

  The sequence of FIG. 33 is for changing the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, and the sequence of FIG. 34 is for changing the magnetoresistive effect element MTJ from the parallel state to the antiparallel state. is there.

  CASE 1 is an angle from the state in which the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ coincides with the long axis of the conductive wire (lower electrode) when viewed from the upper surface of the magnetoresistive effect element MTJ. This is a case where it is rotated left by θ (0 <θ ≦ 45 °), and CASE 2 is a case where it is rotated right.

  Other conditions in the magnetization reversal period are the same as those in the fourth embodiment.

  The difference between CASE 1 and CASE 2 is that the direction of the magnetic field H generated by the spin injection current and the magnetic body having a large volume (thickness) of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. There is a relationship with the direction of the electron spin (magnetization direction). The direction of the magnetic field H itself is the same in CASE 1 and CASE 2, but the relationship between the two differs because the rotation direction of the magnetoresistive element MTJ is different.

  That is, in CASE 1, the relative angle x between the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) having a large volume at the start of magnetization reversal is 90 ° <relative Whereas the angle x ≦ 135 °, in CASE 2, the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) having a large volume at the start of magnetization reversal The relative angle x is 45 ° ≦ relative angle x <90 °.

  In this case, in CASE 1, there is assistance for magnetization reversal by the magnetic field H in almost all of the magnetization reversal periods (A to B) in which the spin injection current continues to flow, but in CASE 2, in the initial period of the magnetization reversal period, that is, Only in the initial generation (A) of the spin injection current (magnetic field assist) is the magnetization reversal assist by the magnetic field H.

  Specifically, in the case of CASE 2, the magnetic field H assists the magnetization reversal in the initial stage from the generation of the magnetic field H until the magnetization direction of the magnetic layer having a large volume becomes the same as the direction of the magnetic field H. However, after that, the magnetic field H disturbs the magnetization reversal. That is, since the relative angle between the direction of the magnetic field H and the magnetization direction of the magnetic layer having a large volume at the start of magnetization reversal is small, the assist period is also shortened.

  On the other hand, in the case of CASE 1, since the relative angle between the direction of the magnetic field H and the magnetization direction of the magnetic layer having a large volume at the start of magnetization reversal is large, the magnetic field H generated by the spin injection current is Assists magnetization reversal by spin injection until the end of the magnetization reversal period.

  Thus, the assist effect of the spin transfer magnetization reversal by the assist magnetic field varies depending on the direction in which the magnetoresistive effect element is tilted (left rotation or right rotation).

  From this example, in the case of the bottom pin type (rightward of the pinned layer), the magnetization easy axis of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is seen from the upper surface of the magnetoresistive effect element MTJ. It can be seen that it is only necessary to rotate counterclockwise by an angle θ from a state where it coincides with the major axis of the lower electrode.

B. Bottom pin type (pinned layer left)
35 and 36 show a magnetization reversal sequence for a bottom pin type (pinned layer leftward) magnetoresistive effect element.

  The sequence in FIG. 35 is for changing the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, and the sequence in FIG. 36 is for changing the magnetoresistive effect element MTJ from the parallel state to the antiparallel state. is there.

  CASE 1 is an angle from the state in which the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ coincides with the long axis of the conductive wire (lower electrode) when viewed from the upper surface of the magnetoresistive effect element MTJ. This is a case where it is rotated right by θ (0 <θ ≦ 45 °), and CASE 2 is a case where it is rotated left.

  Other conditions in the magnetization reversal period are the same as those in the fourth embodiment.

  In CASE 1, the relative angle x between the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) having a large volume at the start of magnetization reversal is 90 ° <relative angle x Whereas ≦ 135 °, in CASE 2, the relative angle between the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) with a large volume at the start of magnetization reversal x is 45 ° ≦ relative angle x <90 °.

  In this case, as in the bottom pin type (rightward to the pinned layer), in CASE 1, there is assistance for magnetization reversal by the magnetic field H in almost all magnetization reversal periods (A to B) in which the spin injection current continues to flow. In 2, there is an assist of magnetization reversal by the magnetic field H only at the beginning of the magnetization reversal period, that is, at the initial generation (A) of the spin injection current (magnetic field assist).

  Note that the bottom pin type (pinned layer rightward) and the bottom pin type (pinned layer leftward) differ in that the magnetization of the SAF free layer in the former is reversed in the clockwise direction, whereas the latter is different from that in the SAF free layer. The magnetization is reversed counterclockwise.

  Thus, the assist effect of the spin transfer magnetization reversal by the assist magnetic field varies depending on the direction in which the magnetoresistive effect element is tilted (left rotation or right rotation).

  According to this example, in the case of the bottom pin type (leftward of the pinned layer), the magnetization easy axis of the magnetic body on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is seen from the upper surface of the magnetoresistive effect element MTJ. It can be seen that it is only necessary to rotate right by an angle θ from a state where it coincides with the major axis of the lower electrode.

C. Top pin type (pinned layer facing right)
37 and 38 show a magnetization reversal sequence for a top pin type (rightward pinned layer) magnetoresistive effect element.

  The sequence in FIG. 37 is for changing the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, and the sequence in FIG. 38 is for changing the magnetoresistive effect element MTJ from the parallel state to the antiparallel state. is there.

  CASE 1 is an angle from the state in which the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ coincides with the long axis of the conductive wire (lower electrode) when viewed from the upper surface of the magnetoresistive effect element MTJ. This is a case where it is rotated right by θ (0 <θ ≦ 45 °), and CASE 2 is a case where it is rotated left.

  Other conditions in the magnetization reversal period are the same as those in the fourth embodiment.

  The difference between CASE 1 and CASE 2 is that the direction of the magnetic field H generated by the spin injection current and the magnetic body having a large volume (thickness) of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. There is a relationship with the direction of the electron spin (magnetization direction). The direction of the magnetic field H itself is the same in CASE 1 and CASE 2, but the relationship between the two differs because the rotation direction of the magnetoresistive element MTJ is different.

  That is, in CASE 1, the relative angle x between the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) having a large volume at the start of magnetization reversal is 90 ° <relative Whereas the angle x ≦ 135 °, in CASE 2, the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) having a large volume at the start of magnetization reversal The relative angle x is 45 ° ≦ relative angle x <90 °.

  In this case, in CASE 1, there is assistance for magnetization reversal by the magnetic field H in almost all of the magnetization reversal periods (A to B) in which the spin injection current continues to flow, but in CASE 2, in the initial period of the magnetization reversal period, that is, Only in the initial generation (A) of the spin injection current (magnetic field assist) is the magnetization reversal assist by the magnetic field H.

  Specifically, in the case of CASE 2, the magnetic field H assists the magnetization reversal in the initial stage from the generation of the magnetic field H until the magnetization direction of the magnetic layer having a large volume becomes the same as the direction of the magnetic field H. However, after that, the magnetic field H disturbs the magnetization reversal. That is, since the relative angle between the direction of the magnetic field H and the magnetization direction of the magnetic layer having a large volume at the start of magnetization reversal is small, the assist period is also shortened.

  On the other hand, in the case of CASE 1, since the relative angle between the direction of the magnetic field H and the magnetization direction of the magnetic layer having a large volume at the start of magnetization reversal is large, the magnetic field H generated by the spin injection current is Assists magnetization reversal by spin injection until the end of the magnetization reversal period.

  Thus, the assist effect of the spin transfer magnetization reversal by the assist magnetic field varies depending on the direction in which the magnetoresistive effect element is tilted (left rotation or right rotation).

  According to this example, in the case of the top pin type (toward the pinned layer rightward), the magnetization easy axis of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is defined as the conductive wire as viewed from the upper surface of the magnetoresistive effect element MTJ. It can be seen that it is sufficient to rotate rightward by an angle θ from a state where it coincides with the major axis of the (lower electrode).

D. Top pin type (pinned layer facing left)
39 and 40 show a magnetization reversal sequence for a top pin type (pinned layer leftward) magnetoresistive effect element.

  The sequence of FIG. 39 is for changing the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, and the sequence of FIG. 40 is for changing the magnetoresistive effect element MTJ from the parallel state to the antiparallel state. is there.

  CASE 1 is an angle from the state in which the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ coincides with the long axis of the conductive wire (lower electrode) when viewed from the upper surface of the magnetoresistive effect element MTJ. This is a case where it is rotated left by θ (0 <θ ≦ 45 °), and CASE 2 is a case where it is rotated right.

  Other conditions in the magnetization reversal period are the same as those in the fourth embodiment.

  In CASE 1, the relative angle x between the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) having a large volume at the start of magnetization reversal is 90 ° <relative angle x Whereas ≦ 135 °, in CASE 2, the relative angle between the direction of the magnetic field H and the direction of the electron spin (magnetization direction) in the magnetic layer (thickness) with a large volume at the start of magnetization reversal x is 45 ° ≦ relative angle x <90 °.

  In this case, as in the case of the top pin type (rightward of the pinned layer), in CASE 1, there is an assist of magnetization reversal by the magnetic field H in almost all of the magnetization reversal periods (A to B) in which the spin injection current continues to flow. In CASE 2, there is assistance for magnetization reversal by the magnetic field H only at the beginning of the magnetization reversal period, that is, at the initial generation (A) of the spin injection current (magnetic field assist).

  Note that the top pin type (pinned layer rightward) and the top pin type (pinned layer leftward) differ in that the magnetization of the SAF free layer is reversed in the counterclockwise direction, whereas the latter is SAF free. The magnetization of the layer is reversed clockwise.

  Thus, the assist effect of the spin transfer magnetization reversal by the assist magnetic field varies depending on the direction in which the magnetoresistive effect element is tilted (left rotation or right rotation).

  According to this example, in the case of the top pin type (leftward of the pinned layer), the magnetization easy axis of the magnetic body on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is defined as the conductive wire as viewed from the upper surface of the magnetoresistive effect element MTJ. It can be seen that it is only necessary to rotate counterclockwise by an angle θ from a state where it coincides with the major axis of the (lower electrode).

E. Summary
As described above, the assist effect varies depending on the direction in which the magnetoresistive effect element MTJ is tilted. The tilt direction depends on factors such as the magnetoresistive effect element MTJ structure (bottom pin type or top pin type) and the magnetization direction of the pinned layer. Different.

  As described in the fourth embodiment, the important points are the direction of the magnetic field generated by the spin injection current at the start of the magnetization reversal and the magnetic volume having a large volume of the two magnetic bodies of the SAF-free layer. The relative angle x with the direction of the electron spin in the body (magnetization direction) is 90 ° <relative angle x ≦ 135 °.

(6) Sixth embodiment
The sixth embodiment relates to a technique for generating an assist magnetic field with an assist current different from a spin injection current.

  That is, the spin injection current path and the assist current path are separated, and a conductive line (write line) through which the assist current flows is newly provided.

A. Structure
41 and 42 show the memory cell structure of the sixth embodiment.

  An element isolation insulating layer 12 having an STI structure is disposed in the semiconductor substrate 11. In the element region surrounded by the element isolation insulating layer 12, for example, a MISFET is disposed as the switch element SW. One end of the switch element SW is connected to the lower bit line BLd as a conductive line through the contact part A. The lower bit line BLd extends in the column direction, for example.

  The magnetoresistive element MTJ is disposed at one end of the conductive wire 13. The other end of the conductive line 13 is connected to the other end of the switch element SW via the contact part B. 41, the conductive line 13 extends in an oblique direction between the column direction and the row direction perpendicular to the column direction in the example of FIG. 41, and extends in the column direction in the example of FIG.

  An upper bit line BLu as a conductive line is disposed on the magnetoresistive element MTJ via a contact part 14 such as a via plug or a metal hard mask. The upper bit line BLu extends, for example, in the column direction.

  The conductive line (write line) 18 has a yoke structure, and includes a conductor 18a and a soft magnetic body 18b that covers the lower surface and side surfaces of the conductor 18a. 41, the conductive line 18 extends in the column direction in the example of FIG. 41, and extends in the row direction in the example of FIG.

  Here, the magnetoresistive effect element MTJ is laid out so that the angle θ between the easy axis of magnetization and the long axis of the conductive wire 13 is a value within the range of 0 ° <θ ≦ 45 °.

  The direction in which the magnetoresistive effect element MTJ is tilted is in principle according to the fifth embodiment.

  However, in the sixth embodiment, by providing the conductive wire 18 for generating the assist magnetic field independently, the maximum is provided if the condition of the angle θ is satisfied regardless of the direction in which the magnetoresistive effect element MTJ is inclined. The assist effect can always be obtained.

B. Magnetization reversal mechanism
Hereinafter, a magnetization reversal mechanism for always obtaining the maximum assist effect regardless of the direction in which the magnetoresistive element MTJ is tilted by controlling the magnetization reversal assist period by the magnetic field will be described.

  43 and 44 show a magnetization reversal sequence for the bottom pin / top pin type magnetoresistive effect element.

  The sequence in FIG. 43 is for changing the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, and the sequence in FIG. 44 is for changing the magnetoresistive effect element MTJ from the parallel state to the antiparallel state. is there.

  In the fifth embodiment, in the case of the bottom pin type (pinned layer rightward) and the top pin type (pinned layer leftward), left rotation, top pin type (pinned layer rightward) and bottom pin type (pinned layer leftward) In this case, since it has been described that the maximum assist effect can be obtained by rotating to the right, in the present embodiment, the following case is considered as the direction in which the magnetoresistive element MTJ is inclined.

  In the case of the bottom pin type (rightward of the pinned layer), the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is seen from the upper surface of the magnetoresistive effect element MTJ. Rotate clockwise by an angle θ (0 <θ ≦ 45 °) from a state where it matches the long axis.

  In the case of the top pin type (to the right of the pinned layer), the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ is viewed from the top surface of the magnetoresistive effect element MTJ. Rotate counterclockwise by an angle θ (0 <θ ≦ 45 °) from a state that coincides with the major axis of.

  First, a spin injection current and an assist current are generated.

  The generation time of both may be the same or may be shifted from each other. When the generation times of both are shifted, the spin injection current may be first or the assist current may be first.

  As described in the fifth embodiment, when the magnetoresistive element MTJ is tilted under the above conditions, the magnetic field H is applied only in the initial period of the magnetization reversal period, that is, in the initial generation (A) of the spin injection current (magnetic field assist). There is assistance for magnetization reversal.

  Therefore, the assist current flows until the magnetization direction of the magnetic layer having a large volume of the SAF-free layer becomes the same as the direction of the magnetic field H, and thereafter, the assist current is cut off and magnetization reversal is performed only by the spin injection current. .

  The point in time when the magnetization direction of the magnetic layer having a large volume of the SAF-free layer becomes the same as the direction of the magnetic field H is before the midpoint of the period during which the spin injection current is flowing.

  In the case of the bottom pin type (pinned layer leftward), when the magnetoresistive element MTJ is rotated counterclockwise by an angle θ (0 <θ ≦ 45 °), and in the case of the top pin type (pinned layer leftward), The present embodiment is also effective for each case where the magnetoresistive element MTJ is rotated clockwise by an angle θ (0 <θ ≦ 45 °).

C. Summary
Thus, in the magnetization reversal period due to the spin injection current (A to B), if the magnetic field assist is performed only in the initial stage (A), regardless of the direction of tilting the magnetoresistive element (left rotation or right rotation), The maximum assist effect can be obtained.

  In the sixth embodiment, the strength of the assist magnetic field H is preferably set within a range of ˜several 10 Oe in order to prevent crosstalk between the conductive lines 13, 18, BLu, BLd.

(7) Seventh embodiment
The seventh embodiment relates to a magnetization reversal mechanism for a magnetoresistive effect element having a single free layer (single layer free).

  Even when the single layer free is used, the magnetization reversal mechanism is the same as that when the SAF-free layer is used (fourth and fifth embodiments).

  In both cases where the pinned layer is directed to the right and the pinned layer is directed to the left, the basic concept is the same as when the SAF-free layer is used, and therefore only the case where the pinned layer is directed to the right will be described.

  45 and 46 show a magnetization reversal mechanism for a bottom pin type (pinned layer rightward) magnetoresistive effect element.

  When the magnetoresistive effect element MTJ is a bottom pin type (rightward of the pinned layer), the magnetization easy axis of the free layer of the magnetoresistive effect element MTJ is aligned with the major axis of the conductive wire (lower electrode) 13 when viewed from the upper surface. Rotate counterclockwise to tilt the angle θ (0 ° <θ ≦ 45 °).

  47 and 48 show a magnetization reversal mechanism for a top pin type (pinned layer rightward) magnetoresistive effect element.

  When the magnetoresistive effect element MTJ is a top pin type (rightward of the pinned layer), the easy axis of magnetization of the free layer of the magnetoresistive effect element MTJ coincides with the major axis of the conductive wire (lower electrode) 13 when viewed from the upper surface. Rotate clockwise from angle θ (0 ° <θ ≤ 45 °).

  49 and 50 show the magnetization reversal sequence for the bottom pin / top pin type (pinned layer rightward) magnetoresistive effect element.

  The sequence in FIG. 49 is for changing the magnetoresistive effect element MTJ from the antiparallel state to the parallel state, and the sequence in FIG. 50 is for changing the magnetoresistive effect element MTJ from the parallel state to the antiparallel state. is there.

  As described above, in the case of the bottom pin type (pinned layer rightward), the magnetoresistive effect element MTJ is rotated counterclockwise by the angle θ, and in the case of the top pin type (pinned layer rightward), the magnetoresistive effect element MTJ is angled. Rotate right by θ.

  Here, the relative angle x between the direction of the assist magnetic field H and the direction of the electron spin (magnetization direction) in the free layer at the start of magnetization reversal is set to 90 ° <relative angle x ≦ 135 °. In this case, as in the case of the SAF-free layer structure, the magnetization reversal assist by the assist magnetic field H can be performed in almost all the magnetization reversal periods in which the spin injection current continues to flow.

  Even when the single layer free is used, if a conductive line for flowing an assist current is provided independently and the assist current path and the spin injection current path are separated, the assist is performed as in the sixth embodiment. By controlling the period, the maximum assist effect can be obtained regardless of the direction in which the magnetoresistive element is tilted.

(8) Eighth embodiment
The eighth embodiment has a feature in that a plurality of magnetoresistive elements are connected in parallel to one switch element with respect to the memory cell structure.

A. Structure
51 and 52 show the memory cell structure of the eighth embodiment.

  An element isolation insulating layer 12 having an STI structure is disposed in the semiconductor substrate 11. In the element region surrounded by the element isolation insulating layer 12, for example, a MISFET is disposed as the switch element SW. One end of the switch element SW is connected to the lower bit line BLd as a conductive line through the contact part A. The lower bit line BLd extends in the column direction, for example.

  The magnetoresistive effect elements MTJ1 and MTJ2 are arranged at one end of the conductive line 13, respectively. The magnetoresistive effect element MTJ1 is arranged at the upper part of one end of the conductive line 13, and the magnetoresistive effect element MTJ2 is arranged at the lower part of one end of the conductive line 13.

  The conductive wire 13 has a yoke structure and is composed of a conductor 13a and a soft magnetic body 13b formed on the inside and side surfaces of the conductor 13a. The other end of the conductive line 13 is connected to the other end of the switch element SW via the contact part B.

  Above the magnetoresistive effect element MTJ1, an upper bit line BLu1 as a conductive line is disposed via a contact part 14 such as a via plug or a metal hard mask. The upper bit line BLu1 extends in the column direction, for example.

  Similarly, an upper bit line BLu2 as a conductive line is disposed under the magnetoresistive element MTJ2 via a contact part 14 such as a via plug or a metal hard mask. In the example of FIG. 51, the upper bit line BLu2 extends in the column direction, and in the example of FIG. 52, the upper bit line BLu2 extends in the row direction.

  The structures of the magnetoresistive elements MTJ1 and MTJ2 are the same type (bottom pin type / top pin type). Data can be independently written in the magnetoresistive elements MTJ1 and MTJ2, and complementary data can be simultaneously written.

  Here, the magnetoresistive effect element MTJ is laid out so that the angle θ between the easy axis of magnetization and the long axis of the conductive wire 13 is a value within the range of 0 ° <θ ≦ 45 °. The direction in which the magnetoresistive element MTJ is tilted (left rotation or right rotation) is in accordance with the fifth embodiment.

  According to such a structure, a high-speed read / write architecture can be realized. For example, by storing complementary data in the two magnetoresistive effect elements MTJ1 and MTJ2, it is possible to realize differential reading that simultaneously reads data from the magnetoresistive effect elements MTJ1 and MTJ2.

  As for writing, complementary data can be simultaneously written in the magnetoresistive elements MTJ1 and MTJ2.

B. Magnetization reversal mechanism
a. Bottom pin type (pinned layer facing right)
53 to 56 show a magnetization reversal mechanism for a bottom pin type (pinned layer rightward) magnetoresistive effect element.

  The magnetoresistive element MTJ <b> 1 is disposed on the conductive line 13. That is, the pinned layer of the magnetoresistive effect element MTJ1 is closer to the conductive line 13 than the free layer of the magnetoresistive effect element MTJ1.

  In this case, as shown in FIGS. 53 and 55, the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive element MTJ1 is viewed from the top surface (on the side of the upper bit line BLu1 in FIGS. 51 and 52). From the state coincident with the long axis of the conductive line 13, the counterclockwise tilt is made by an angle θ (0 <θ ≦ 45 °).

  In addition, the magnetoresistive element MTJ <b> 2 is disposed below the conductive line 13. That is, the free layer of the magnetoresistive element MTJ2 is closer to the conductive line 13 than the pinned layer of the magnetoresistive element MTJ2.

  In this case, as shown in FIGS. 54 and 56, the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ2 is viewed from the bottom surface (on the side of the upper bit line BLu2 in FIGS. 51 and 52). From the state coincident with the long axis of the conductive wire 13, it is tilted by an angle θ (0 <θ ≦ 45 °) by rotating it clockwise.

  In FIGS. 54 and 56, the magnetoresistive effect element MTJ2 is viewed from the upper surface (the conductive bit 13 side in FIGS. 51 and 52 is viewed from the upper bit line BLu2 side). This is to correspond to FIG. 53 and FIG. 55, and naturally, when viewed from the lower surface, the rotation is clockwise.

  When the magnetization state of the magnetoresistive element MTJ1 is changed from the antiparallel state to the parallel state, the spin injection current Is flows from one end of the conductive line 13 to the other end as shown in FIG. Here, one end of the conductive wire 13 is an end portion on the side where the magnetoresistive effect element MTJ1 is disposed, and the other end is an end portion on the side where the switch element SW is connected.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the pinned layer of the magnetoresistive effect element MTJ1 to the free layer. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive element MTJ1 when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ1 is changed from the antiparallel state to the parallel state.

  Similarly, when the magnetization state of the magnetoresistive effect element MTJ2 is changed from the parallel state to the antiparallel state, the spin injection current Is flows from one end of the conductive line 13 to the other end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive effect element MTJ2. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts leftward with respect to the magnetoresistive element MTJ2 when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ2 is changed from the parallel state to the antiparallel state.

  Further, when the magnetization state of the magnetoresistive element MTJ1 is changed from the parallel state to the antiparallel state, the spin injection current Is flows from the other end of the conductive line 13 toward one end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive effect element MTJ1. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive element MTJ1 when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Accordingly, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ1 is changed from the parallel state to the antiparallel state.

  Similarly, when the magnetization state of the magnetoresistive element MTJ2 is changed from the antiparallel state to the parallel state, the spin injection current Is is caused to flow from the other end of the conductive line 13 toward one end as shown in FIG.

  In this case, the spin-polarized electron flow (spin current) generated by the spin injection current Is is directed from the pinned layer of the magnetoresistive effect element MTJ2 to the free layer. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts leftward with respect to the magnetoresistive effect element MTJ2 when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ2 is changed from the antiparallel state to the parallel state.

  Note that the bottom pin type (pinned layer leftward) magnetization reversal mechanism can be considered in the same manner as the bottom pin type (pinned layer rightward), and therefore the description thereof is omitted here.

b. Top pin type (pinned layer facing right)
57 to 60 show a magnetization reversal mechanism for a top pin type (pinned layer rightward) magnetoresistive effect element.

  The magnetoresistive element MTJ <b> 1 is disposed on the conductive line 13. That is, the free layer of the magnetoresistive effect element MTJ1 is closer to the conductive line 13 than the pinned layer of the magnetoresistive effect element MTJ1.

  In this case, as shown in FIGS. 57 and 59, the magnetization easy axis of the magnetic body on the pinned layer side of the free layer of the magnetoresistive element MTJ1 is viewed from the top surface (on the side of the upper bit line BLu1 in FIGS. 51 and 52). From the state coincident with the long axis of the conductive wire 13, it is tilted by an angle θ (0 <θ ≦ 45 °) by rotating it clockwise.

  In addition, the magnetoresistive element MTJ <b> 2 is disposed below the conductive line 13. That is, the pinned layer of the magnetoresistive effect element MTJ2 is closer to the conductive line 13 than the free layer of the magnetoresistive effect element MTJ2.

  In this case, as shown in FIGS. 58 and 60, the easy axis of magnetization of the magnetic material on the pinned layer side of the free layer of the magnetoresistive effect element MTJ2 is viewed from the bottom surface (on the side of the upper bit line BLu2 in FIGS. 51 and 52). From the state coincident with the long axis of the conductive line 13, the counterclockwise tilt is made by an angle θ (0 <θ ≦ 45 °).

  In FIGS. 58 and 60, the magnetoresistive element MTJ2 is viewed from the top surface (from the conductive line 13 side to the upper bit line BLu2 side in FIGS. 51 and 52), and thus is rotated clockwise. This is to correspond to FIG. 57 and FIG. 59, and naturally, when viewed from the lower surface, the rotation is counterclockwise.

  When the magnetization state of the magnetoresistive element MTJ1 is changed from the antiparallel state to the parallel state, the spin injection current Is is caused to flow from the other end of the conductive line 13 toward one end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the pinned layer of the magnetoresistive effect element MTJ1 to the free layer. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive element MTJ1 when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ1 is changed from the antiparallel state to the parallel state.

  Similarly, when the magnetization state of the magnetoresistive element MTJ2 is changed from the parallel state to the antiparallel state, the spin injection current Is flows from the other end of the conductive line 13 toward one end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive effect element MTJ2. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts leftward with respect to the magnetoresistive effect element MTJ2 when one end is viewed from the other end of the conductive line 13. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ2 is changed from the parallel state to the antiparallel state.

  Further, when the magnetization state of the magnetoresistive element MTJ1 is changed from the parallel state to the antiparallel state, the spin injection current Is is passed from one end of the conductive line 13 to the other end as shown in FIG.

  In this case, the spin-polarized electron flow (spin flow) generated by the spin injection current Is is directed from the free layer to the pinned layer of the magnetoresistive effect element MTJ1. At this time, the electron spin polarized in the direction opposite to the electron spin in the pinned layer is reflected by the pinned layer and gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts rightward with respect to the magnetoresistive element MTJ1 when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Accordingly, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ1 is changed from the parallel state to the antiparallel state.

  Similarly, when the magnetization state of the magnetoresistive effect element MTJ2 is changed from the antiparallel state to the parallel state, the spin injection current Is flows from one end of the conductive line 13 toward the other end, as shown in FIG.

  In this case, the spin-polarized electron flow (spin current) generated by the spin injection current Is is directed from the pinned layer of the magnetoresistive effect element MTJ2 to the free layer. At this time, the electron spin polarized in the same direction as the electron spin in the pinned layer gives torque to the electron spin in the magnetic body on the tunnel barrier layer side of the SAF-free layer.

  At the same time, the magnetic field H generated by the spin injection current Is acts leftward with respect to the magnetoresistive element MTJ1 when the other end of the conductive line 13 is viewed. The direction of the magnetic field H is 90 ° <relative angle x ≦ with respect to the direction (magnetization direction) of electron spin in the magnetic body having a large volume of the two magnetic bodies of the SAF-free layer at the start of magnetization reversal. The direction is 135 °.

  Therefore, the magnetization of the SAF-free layer is reversed, and the magnetization state of the magnetoresistive element MTJ2 is changed from the antiparallel state to the parallel state.

  Note that the top pin type (pinned layer leftward) magnetization reversal mechanism can be considered in the same manner as the top pin type (pinned layer rightward), and therefore the description thereof is omitted here.

C. Summary
Thus, according to the eighth embodiment, data can be written independently to the two magnetoresistive elements MTJ1 and MTJ2 arranged above and below the conductive line 13, and complementary data can be written. You can write at the same time.

(9) Ninth embodiment
The ninth embodiment relates to materials and sizes.

  First, the pinned layer as the magnetization pinned layer preferably has unidirectional anisotropy, and the free layer as the magnetic recording layer preferably has uniaxial anisotropy. Further, the thicknesses of the pinned layer and the free layer are preferably set to values in the range of 0.1 nm to 100 nm, respectively.

  The ferromagnetic material constituting the pinned layer or the free layer is required not to be superparamagnetic. For this purpose, it is preferable that the thickness of both is 0.4 nm or more.

When the magnetization direction of the pinned layer is fixed by an antiferromagnetic layer, the antiferromagnetic layer is composed of Fe (iron) -Mn (manganese), Pt (platinum) -Mn (manganese), Pt (platinum) -Cr (chromium). -Mn (manganese), Ni (nickel) -Mn (manganese), Ir (iridium) -Mn (manganese), NiO (nickel oxide), and composed of one selected from Fe ₂ O ₃ .

  In the magnetic body constituting the antiferromagnetic layer, Ag (silver), Cu (copper), Au (gold), Al (aluminum), Mg (magnesium), Si (silicon), Bi (bismuth), Ta (tantalum) ), B (boron), C (carbon), O (oxygen), N (nitrogen), Pd (palladium), Pt (platinum), Zr (zirconium), Ir (iridium), W (tungsten), Mo (molybdenum) ), Nb (niobium), B (boron) and other nonmagnetic elements may be added to control the physical properties including magnetic properties, crystallinity, mechanical properties, chemical properties, and the like.

  When the magnetization direction of the pinned layer is fixed by the antiferromagnetic layer, the magnetization of the pinned layer is hardly affected by the magnetic field from the bit line or the word line, and the magnetization is firmly fixed. Further, the stray field from the pinned layer can be reduced, and the thickness of the ferromagnetic material constituting the pinned layer can be changed to adjust the magnetization shift of the free layer.

  The pinned layer has a three-layer structure, for example, Co (Co-Fe) / Ru / Co (Co-Fe), Co (Co-Fe) / Ir / Co (Co-Fe), Co (Co-Fe) / Os (Osnium) / Co- (Co-Fe), Co (Co-Fe) / Re (Rhenium) / Co- (Co-Fe), Amorphous materials such as Co-Fe-B / Ru / Co-Fe-B, etc. Amorphous material such as Co-Fe-B / Amorphous material such as Ir / Co-Fe-B, Amorphous material such as Co-Fe-B / Amorphous material such as Os / Co-Fe-B, Co- It consists of amorphous materials such as Fe-B / amorphous materials such as Re / Co-Fe-B.

  The free layer may have a two-layer structure made of soft magnetic material / ferromagnetic material or a three-layer structure made of ferromagnetic material / soft magnetic material / ferromagnetic material. The free layer has a three-layer structure of ferromagnetic material / non-magnetic material / ferromagnetic material, and further has a five-layer structure of ferromagnetic material / non-magnetic material / ferromagnetic material / non-magnetic material / ferromagnetic material. By controlling the strength of the magnetic interaction between the magnetic bodies, an increase in power consumption can be suppressed even when the size of the free layer is submicron or less.

  The type and thickness of the ferromagnetic material constituting such a free layer are determined in consideration of the characteristics of the magnetoresistive element.

  In particular, the ferromagnetic material in contact with the tunnel barrier layer has a large influence on the MR ratio, so that a material that increases the MR ratio of the magnetoresistive effect element, for example, Co-Fe, Co-Fe-Ni, Fe rich Consists of Ni-Fe, etc. In addition, the ferromagnetic material that does not contact the tunnel barrier layer is made of Ni-rich Ni-Fe, Ni-rich Ni-Fe-Co, etc., and reduces the switching magnetic field while ensuring a large MR ratio.

  In addition, the structure of the free layer can be a multilayer structure composed of two ferromagnets and a non-magnetic material between them, and the magnetic interaction between the two ferromagnets can be antiferromagnetically or ferromagnetically coupled. This can contribute to further reduction of the switching magnetic field.

  In the magnetic body constituting the free layer, Ag (silver), Cu (copper), Au (gold), Al (aluminum), Mg (magnesium), Si (silicon), Bi (bismuth), Ta (tantalum), B (boron), C (carbon), O (oxygen), N (nitrogen), Pd (palladium), Pt (platinum), Zr (zirconium), Ir (iridium), W (tungsten), Mo (molybdenum), A nonmagnetic element such as Nb (niobium) or B (boron) may be added to control the physical properties including magnetic properties, crystallinity, mechanical properties, chemical properties, and the like.

  Nonmagnetic materials are Ag (silver), Cu (copper), Au (gold), Al (aluminum), Ru (ruthenium), Os (osnium), Re (rhenium), Si (silicon), Bi (bismuth), Ta (tantalum), B (boron), C (carbon), Pd (palladium), Pt (platinum), Zr (zirconium), Ir (iridium), W (tungsten), Mo (molybdenum), Nb (niobium), Or it comprises an alloy containing at least one of these.

The tunnel barrier layer consists of Al ₂ O ₃ (aluminum oxide), SiO ₂ (silicon oxide), MgO (magnesium oxide), AlN (aluminum nitride), Bi ₂ O ₃ (bismuth oxide), MgF ₂ (magnesium fluoride), Consists of insulators (dielectrics) such as CaF ₂ (calcium fluoride), SrTiO ₂ (titanium oxide / strontium), AlLaO ₃ (lanthanum oxide / aluminum), Al-NO (aluminum oxynitride).

  Since the thickness of the tunnel barrier layer is preferably thin enough to allow the tunnel current to flow, it is set to a value of 10 nm or less, for example.

  In addition, these compounds do not need to have a completely accurate composition in terms of stoichiometry, and defects such as oxygen, nitrogen, fluorine and the like may exist.

Each layer constituting the magnetoresistive effect element is formed on the upper portion of the substrate by using a general thin film forming method such as sputtering, CVD, or molecular beam epitaxial. Here, as the substrate, for example, a substrate made of SiO ₂ (silicon oxide), Al ₂ O ₃ (aluminum oxide), spinel, AlN (aluminum nitride), or the like can be used in addition to a semiconductor substrate such as Si (silicon). .

  Moreover, you may arrange | position a base layer, a protective layer, or a hard mask between a board | substrate and a magnetoresistive effect element.

  These layers are Ta (tantalum), Ti (titanium), Pt (platinum), Pd (palladium), Au (gold), Ti (titanium) / Pt (platinum), Ta (tantalum) / Pt (platinum), Ti (titanium) / Pd (palladium), Ta (tantalum) / Pd (palladium), Cu (copper), Al (aluminum) -Cu (copper), Ru (ruthenium), Ir (iridium), Os (osmium), etc. Consists of.

  The magnetic body constituting the magnetoresistive effect element is generally an alloy selected from the group of Ni-Fe, Co-Fe, Co-Fe-Ni, (Co, Fe, Ni) -B, (Co, Fe, Ni) -B- (P, Al, Mo, Nb, Mn), Co- (Zr, Hf, Nb, Ta, Ti), an amorphous material selected from the group, and Co-Cr-Fe-Al , Co-Cr-Fe-Si, Co-Mn-Si, or Co-Mn-Al.

  However, a plurality of elements included in parentheses means that at least one of them is selected.

(10) Tenth embodiment
The tenth embodiment relates to a technique for efficiently applying an assist magnetic field to a magnetoresistive effect element by a yoke structure.

  61 and 62 show examples of the memory cell structure.

  An element isolation insulating layer 12 having an STI structure is disposed in the semiconductor substrate 11. In the element region surrounded by the element isolation insulating layer 12, for example, a MISFET (including a MOSFET) is disposed as the switch element SW. One end of the switch element SW is connected to the lower bit line BLd as a conductive line through the contact part A. The lower bit line BLd extends in the column direction, for example.

  In the example of FIG. 61, the conductive wire 13 has a yoke structure and is composed of a conductor 13a and a soft magnetic body 13b that covers the lower surface and side surfaces of the conductor 13a. The magnetoresistive element MTJ is disposed at one end of the conductive wire 13. The other end of the conductive line 13 is connected to the other end of the switch element SW via the contact part B.

  On the magnetoresistive effect element MTJ, an upper bit line BLu as a conductive line is arranged via a contact part 14 such as a via plug or a metal hard mask. The upper bit line BLu extends, for example, in the column direction. The upper bit line BLu has a yoke structure, and includes a conductor 13c and a soft magnetic body 13d that covers the upper surface and side surfaces of the conductor 13c.

  In the example of FIG. 61, each of the conductive lines arranged above and below the magnetoresistive effect element MTJ has a yoke structure, and in the example of FIG. 62, the conductive lines arranged above the magnetoresistive effect element MTJ are It has a yoke structure.

  The layout of the magnetoresistive element MTJ is according to the fourth and fifth embodiments.

  According to such a structure, the magnetic field lines of the assist magnetic field can be converged and the assist magnetic field can be efficiently applied to the magnetoresistive effect element, similarly to the case where only the conductive wire 13 has the yoke structure.

4). Example
Examples of the present invention will be described below.

(1) First embodiment
In the first embodiment, the effect of reducing the spin injection current is verified based on two bottom pin type samples.

  One is a sample (Sample 1) having the bottom pin type magnetoresistive effect element of FIG. 17A and the memory cell structure of FIG. 24, and the other is the bottom pin type magnetoresistive effect element of FIG. This is a sample (Sample 2) having the memory cell structure.

  In the case of FIG. 17A, the conductive wire (lower electrode) has a Ta / Cu / Ta laminated structure, and the underlying layer is Ru. The antiferromagnetic layer is Ir-Mn (10 nm), and the ferromagnetic layer as the pinned layer is a three-layer structure of CoFe (2 nm) / Ru (1.5 nm) / CoFeB (2 nm) here. The tunnel barrier layer is made of MgO (1 nm), and the SAF-free layer has a three-layer structure of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm). The cap layer is made of Ru.

  In the case of FIG. 18, the conductive wire (lower electrode) has a Ta / Cu / Ta laminated structure, and the underlying layer is Ru. The antiferromagnetic layer is Ir-Mn (10 nm), and the ferromagnetic layer as the pinned layer is a three-layer structure of CoFe (2 nm) / Ru (1.5 nm) / CoFeB (2 nm) here. The tunnel barrier layer is made of MgO (1 nm), and the SAF-free layer has a three-layer structure of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm). The nonmagnetic layer has a two-layer structure of AlOx (0.6 nm) / Ru (3 nm), and a pinned layer comprising three layers of CoFe (3 nm) / Ru (0.9 nm) / CoFe (3 nm) and Ir on the nonmagnetic layer. An antiferromagnetic layer made of -Mn (10 nm) is disposed. The cap layer is made of Ru.

After forming such a structure, the magnetoresistive effect element is annealed at a temperature of about 360 ° in a state where a magnetic field of constant strength is applied, and further, the size is reduced to, for example, 0.1 × 0.2 μm ² by a fine processing technique. After that, it is completed by performing annealing at a temperature of about 300 ° again with a magnetic field having a constant strength applied.

Here, with respect to Sample 1 and Sample 2, the magnetic reciprocity between two ferromagnetic layers of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm) as a SAF-free layer after annealing at a temperature of about 300 ° The strength of action J _EX is 1.24 erg / cm ² . Regarding Sample 1 and Sample 2, the magnetic interaction between the two ferromagnetic layers of the pinned layer is ferromagnetic coupling.

  Regarding the angle θ between the easy axis of magnetoresistive effect element and the long axis of the conductive wire (lower electrode), there are seven types: 0 °, 5 °, 10 °, 20 °, 30 °, 40 °, 45 ° As prepared, both Sample 1 and Sample 2 can perform magnetization reversal at the smallest spin injection current density when the angle θ is 40 °.

  However, the magnetization reversal mechanism shown in FIGS. 25 and 26 is employed as the magnetization reversal mechanism.

  63 and 64 show the relationship between the spin injection current density and the resistance value of the magnetoresistive element when the angle θ is 40 °.

  63 corresponds to the structure of FIG. 17A, and FIG. 64 corresponds to the structure of FIG. Each figure shows three cases with the strength of the assist magnetic field Hhard caused by the spin injection current as a parameter.

  In the case of Hhard = 20 Oe and Hhard = 20 Oe, it can be seen that the spin injection current density required for magnetization reversal is significantly reduced as compared with the case of Hhard = 0 Oe.

  It is clear that the effect of reducing the spin injection current density obtained by the first embodiment is remarkable as compared with FIG.

  FIG. 65 shows the relationship between the angle θ and the spin injection current density.

  When the angle θ between the easy axis of the magnetoresistive effect element and the long axis of the conductive wire (lower electrode) is in the range of 0 ° <θ ≦ 45 °, the spin injection current density is higher than when the angle θ is 0 °. It can be seen that it has been reduced.

(2) Second embodiment
In the second embodiment, the effect on the reduction of the spin injection current is verified based on two samples of the top pin type.

  One is the sample (Sample 3) having the top pin type magnetoresistive effect element of FIG. 17B and the memory cell structure of FIG. 24, and the other is the top pin type magnetoresistive effect element of FIG. 25 is a sample (Sample 4) having the memory cell structure of FIG.

  In the case of FIG. 17B, the conductive wire (lower electrode) has a Ta / Cu / Ta laminated structure, and the underlying layer is Ru. The SAF-free layer has a three-layer structure of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm), and the tunnel barrier layer is MgO (1 nm). Here, the ferromagnetic layer as the pinned layer has a three-layer structure of CoFe (2 nm) / Ru (1.5 nm) / CoFeB (2 nm), and the antiferromagnetic layer is Pt-Mn (14 nm). The cap layer is made of Ru.

  In the case of FIG. 19, the conductive wire (lower electrode) has a Ta / Cu / Ta laminated structure, and the underlying layer is Ru. The antiferromagnetic layer is Pt-Mn (14 nm), and the ferromagnetic layer as the pinned layer is a three-layer structure of CoFe (4 nm) / Ru (0.9 nm) / CoFe (3 nm) here. The nonmagnetic layer has a two-layer structure of Cu (2 nm) / AlOx (0.6 nm), and the SAF-free layer has a three-layer structure of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm). The tunnel barrier layer is MgO (1 nm), and a pinned layer consisting of three layers of CoFe (2 nm) / Ru (0.9 nm) / CoFe (3 nm) and an antiferromagnetic material consisting of Pt-Mn (14 nm) on the tunnel barrier layer. Arrange the layers. The cap layer is made of Ru.

After forming such a structure, the magnetoresistive effect element is annealed at a temperature of about 360 ° in a state where a magnetic field of constant strength is applied, and further, the size is reduced to, for example, 0.1 × 0.2 μm ² by a fine processing technique. After that, it is completed by performing annealing at a temperature of about 300 ° again with a magnetic field having a constant strength applied.

Here, with respect to Sample 3 and Sample 4, the magnetic mutual between two ferromagnetic layers of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm) as a SAF-free layer after annealing at a temperature of about 300 °. The strength of action J _EX is 1.24 erg / cm ² . Regarding Sample 3 and Sample 4, the magnetic interaction between the two ferromagnetic layers of the pinned layer is ferromagnetic coupling.

  Regarding the angle θ between the easy axis of magnetoresistive effect element and the long axis of the conductive wire (lower electrode), there are seven types: 0 °, 5 °, 10 °, 20 °, 30 °, 40 °, 45 ° As prepared, in both Sample 3 and Sample 4, when the angle θ is 40 °, magnetization reversal is possible with the smallest spin injection current density.

  However, the magnetization reversal mechanism shown in FIGS. 29 and 30 is adopted as the magnetization reversal mechanism.

  66 and 67 show the relationship between the spin injection current density and the resistance value of the magnetoresistive element when the angle θ is 40 °.

  66 corresponds to the structure of FIG. 17B, and FIG. 67 corresponds to the structure of FIG. Each figure shows three cases with the strength of the assist magnetic field Hhard caused by the spin injection current as a parameter.

  In the case of Hhard = 20 Oe and Hhard = 20 Oe, it can be seen that the spin injection current density required for magnetization reversal is significantly reduced as compared with the case of Hhard = 0 Oe.

  It is clear that the effect of reducing the spin injection current density obtained by the second embodiment is remarkable, as compared with FIG. 12, as in the first embodiment.

  FIG. 68 shows the relationship between the angle θ and the spin injection current density.

  When the angle θ between the easy axis of the magnetoresistive effect element and the long axis of the conductive wire (lower electrode) is in the range of 0 ° <θ ≦ 45 °, the spin injection current density is higher than when the angle θ is 0 °. It can be seen that it has been reduced.

  In the second embodiment, the same effect can be obtained even when Cu (2 nm) in the nonmagnetic layer is replaced with Au or Ag.

  When Cu is used for the nonmagnetic layer, the MR ratio can be improved compared to the case of using Au or Ag, but if the resistance value of MgO and AlOx as the insulating layer is different, Cu can be used as the nonmagnetic layer. The effects of the present invention can be obtained.

(3) Third embodiment
In the third embodiment, the effect of reducing the spin injection current is verified for the magnetic random access memory (Sample 5) shown in FIGS.

  As shown in FIG. 24, the memory cell array employs a yoke structure as the conductive line (lower electrode) 13.

  A magnetoresistive element MTJ is disposed on the conductive line 13 via Ru as a base layer. The magnetoresistive element MTJ is, for example, a bottom pin type shown in FIG.

  The antiferromagnetic layer is made of Pt-Mn (14 nm), and the pinned layer has a three-layer structure of CoFe (2 nm) / Ru (1.5 nm) / CoFeB (2 nm). The tunnel barrier layer is made of MgO (1 nm), and the SAF-free layer has a three-layer structure of CoFeB (2 nm) / Ru (0.9 nm) / CoFeB (2 nm). The cap layer is made of Ru.

Regarding the magnetoresistive effect element MTJ, annealing is performed at a temperature of about 360 ° in a state where a constant magnetic field is applied, and further, the size is set to, for example, 0.1 × 0.18 μm ² by a fine processing technique, and then again, Annealing is performed at a temperature of about 300 ° with a constant magnetic field applied. The strength of magnetic interaction J _EX between the two ferromagnetic layers of the SAF-free layer after the latter annealing is 1.24 erg / cm ² . Further, the two ferromagnetic layers of the pinned layer are ferromagnetically coupled.

  The angle θ between the easy axis of the magnetoresistive element and the long axis of the conductive wire (lower electrode) is 30 °.

Then, based on the magnetization reversal mechanism shown in FIGS. 25 and 26, when a current pulse (spin injection current) having a current density of about 4 × 10 ⁶ A / cm ² was generated, writing was performed 8000 times or more with a 100 μsec width pulse ( Even when magnetization reversal was performed, stable operation was ensured as shown in FIG. 69, and further, the tunnel barrier layer was not broken.

5). Other
According to the example of the present invention, a low-power consumption, low-current writing and high-reliability spin memory having thermal fluctuation resistance can be realized.

  The example of the present invention is not limited to the above-described embodiment, and can be embodied by modifying each component without departing from the scope of the invention. Various inventions can be configured by appropriately combining a plurality of constituent elements disclosed in the above-described embodiments. For example, some constituent elements may be deleted from all the constituent elements disclosed in the above-described embodiments, or constituent elements of different embodiments may be appropriately combined.

  For example, materials, thicknesses, shapes, sizes, etc. constituting the ferromagnetic material, insulator, antiferromagnetic material, and non-magnetic material, and the conductive wires and electrodes constituting the magnetoresistive effect element Those that can be appropriately selected by those skilled in the art are naturally included in the scope of the present invention.

Sectional drawing which shows the structural example of a magnetoresistive effect element. The figure which shows the relationship between the strength of the antiferromagnetic coupling of a SAF-free layer, and thermal disturbance tolerance. Sectional drawing which shows the structural example of a memory cell. Sectional drawing which shows the structural example of a memory cell. The figure which shows the relationship between an assist magnetic field and a spin inversion energy barrier. The figure which shows the astroid curve of a single layer-free layer. The figure which shows the relationship between a spin injection current density and the resistance value of a magnetoresistive effect element. The figure which shows the relationship between a spin injection current density and the resistance value of a magnetoresistive effect element. Sectional drawing which shows the structural example of a memory cell. Sectional drawing which shows the structural example of a memory cell. The figure which shows the astroid curve of a SAF-free layer. The figure which shows the relationship between a spin injection current density and the resistance value of a magnetoresistive effect element. The top view which shows the layout in connection with 1st Embodiment. The top view which shows the layout in connection with 1st Embodiment. The figure which shows an astroid curve in case of (theta) = 45 degrees. The figure which shows the relationship between spin relative angle (phi) and the strength of a spin torque. Sectional drawing which shows the magnetoresistive effect element of 2nd Embodiment. Sectional drawing which shows the magnetoresistive effect element of 2nd Embodiment. Sectional drawing which shows the magnetoresistive effect element of 2nd Embodiment. Sectional drawing which shows the magnetoresistive effect element of 2nd Embodiment. Sectional drawing which shows the magnetoresistive effect element of 2nd Embodiment. The figure which shows the memory cell array structure of 3rd Embodiment. The figure which shows the memory cell array structure of 3rd Embodiment. Sectional drawing which shows the memory cell structure of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal mechanism of 4th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. The figure which shows the magnetization reversal sequence of 5th Embodiment. Sectional drawing which shows the memory cell structure of 6th Embodiment. Sectional drawing which shows the memory cell structure of 6th Embodiment. The figure which shows the magnetization reversal sequence of 6th Embodiment. The figure which shows the magnetization reversal sequence of 6th Embodiment. The figure which shows the magnetization reversal mechanism of 7th Embodiment. The figure which shows the magnetization reversal mechanism of 7th Embodiment. The figure which shows the magnetization reversal mechanism of 7th Embodiment. The figure which shows the magnetization reversal mechanism of 7th Embodiment. The figure which shows the magnetization reversal sequence of 7th Embodiment. The figure which shows the magnetization reversal sequence of 7th Embodiment. Sectional drawing which shows the memory cell structure of 8th Embodiment. Sectional drawing which shows the memory cell structure of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the magnetization reversal mechanism of 8th Embodiment. The figure which shows the memory cell structure of 10th Embodiment. The figure which shows the memory cell structure of 10th Embodiment. The figure which shows the reduction effect of the spin injection current density by 1st Example. The figure which shows the reduction effect of the spin injection current density by 1st Example. The figure which shows the reduction effect of the spin injection current density by 1st Example. The figure which shows the reduction effect of the spin injection current density by 2nd Example. The figure which shows the reduction effect of the spin injection current density by 2nd Example. The figure which shows the reduction effect of the spin injection current density by 2nd Example. The figure which shows the effect regarding the stable operation | movement by 3rd Example.

Explanation of symbols

  11: Semiconductor substrate, 12: Element isolation insulating layer, 13, 18: Conductive line, 13a, 18a: Conductor, 13b, 18b: Soft magnetic material, 14: Contact parts, 15: Word line driver / decoder, 16, 17 : Bit line driver / sinker decoder, SW: switch element, WL: word line, BLu, BLu1, BLu2: upper bit line, BLd: lower bit line, S / A: sense amplifier.

Claims (31)

  A first magnetoresistive element disposed between the first and second conductive lines, one end of the first conductive line and the second conductive line, and a switch connected to the other end of the first conductive line; An element, and a driver / sinker for passing a spin injection current for magnetization reversal by spin torque to the first magnetoresistive element through the first and second conductive lines, and the first magnetoresistive element Includes a magnetic recording layer having a variable magnetization direction and a first magnetic fixed layer to which the magnetization direction is fixed, and an angle θ formed by an easy axis of magnetization of the magnetic recording layer and a long axis of the first conductive line. Is a spin memory characterized by 0 ° <θ ≦ 45 °.   The first magnetoresistance effect element includes a tunnel barrier layer between the magnetic recording layer and the first magnetic pinned layer, and the magnetic recording layer includes two magnetic bodies and a nonmagnetic body therebetween. The spin memory according to claim 1, wherein the two magnetic bodies are antiferromagnetically coupled.   The first magnetoresistance effect element further includes a second magnetic pinned layer to which a magnetization direction is pinned, and the magnetic recording layer is disposed between the first and second magnetic pinned layers. The spin memory according to claim 2.   At least one of the first and second magnetic pinned layers has two magnetic bodies and a non-magnetic body between them, and the two magnetic bodies are antiferromagnetically coupled. The spin memory according to claim 3.   The spin memory according to claim 3 or 4, wherein the magnetization directions of the first and second magnetic pinned layers are pinned by an antiferromagnetic layer, respectively.   6. The magnetic recording layer according to claim 3, wherein in the first and second magnetic pinned layers, the magnetization of the magnetic material on the magnetic recording layer side is opposite to each other, and the non-magnetic material is Ru. 2. The spin memory according to item 1.   In the first and second magnetic pinned layers, the magnetization of the magnetic material on the magnetic recording layer side is in the same direction, and the non-magnetic material is one selected from the group of Cu, Ag, and Au. The spin memory according to claim 3, wherein the spin memory is provided. The spin memory according to any one of claims 2 to 7, wherein the strength of antiferromagnetic coupling between the two magnetic bodies constituting the magnetic recording layer is 0.52 erg / cm ² or more. .   The spin memory according to any one of claims 2 to 8, wherein thicknesses of the two magnetic bodies constituting the magnetic recording layer are different from each other.   The first magnetic pinned layer is closer to the first conductive line than the magnetic recording layer, and the easy axis of magnetization of the magnetic recording layer and the easy axis of magnetization of the first magnetic pinned layer face substantially the same direction. When the magnetization of the magnetic material on the magnetic recording layer side of the first magnetic pinned layer is oriented in a direction closer to one end side than the other end side of the first conductive line, the magnetic recording layer and the first magnetic layer The easy magnetization axis of the pinned layer is rotated from the second conductive line side to the first conductive line side by a left rotation from the state coincident with the long axis by the angle θ. The spin memory according to any one of claims 2 to 9.   The first magnetic pinned layer is closer to the first conductive line than the magnetic recording layer, and the easy axis of magnetization of the magnetic recording layer and the easy axis of magnetization of the first magnetic pinned layer face substantially the same direction. When the magnetization of the magnetic material on the magnetic recording layer side of the first magnetic pinned layer is oriented in a direction closer to the other end side than the one end side of the first conductive line, the magnetic recording layer and the first magnetic layer The easy axis of the pinned layer rotates from the second conductive line side by the angle θ by rotating clockwise from the second conductive line side when the first conductive line side is coincident with the long axis. The spin memory according to any one of claims 2 to 9.   When the magnetization state of the first magnetoresistive element is made parallel, the spin injection current is made to flow from one end to the other end of the first conductive line, and when made antiparallel, the spin injection current is made to be 12. The spin memory according to claim 10, wherein the first conductive wire flows from the other end toward the one end.   The magnetic recording layer is closer to the first conductive line than the first magnetic pinned layer, and the magnetization easy axis of the magnetic recording layer and the magnetization easy axis of the first magnetic pinned layer face substantially the same direction. When the magnetization of the magnetic material on the magnetic recording layer side of the first magnetic pinned layer is oriented in a direction closer to one end side than the other end side of the first conductive line, the magnetic recording layer and the first magnetic layer The easy axis of the pinned layer rotates from the second conductive line side by the angle θ by rotating clockwise from the second conductive line side when the first conductive line side is coincident with the long axis. The spin memory according to any one of claims 2 to 9.   The magnetic recording layer is closer to the first conductive line than the first magnetic pinned layer, and the magnetization easy axis of the magnetic recording layer and the magnetization easy axis of the first magnetic pinned layer face substantially the same direction. When the magnetization of the magnetic material on the magnetic recording layer side of the first magnetic pinned layer is oriented in a direction closer to the other end side than the one end side of the first conductive line, the magnetic recording layer and the first magnetic layer The easy magnetization axis of the pinned layer is rotated from the second conductive line side to the first conductive line side by a left rotation from the state coincident with the long axis by the angle θ. The spin memory according to any one of claims 2 to 9.   When the magnetization state of the first magnetoresistive element is made parallel, the spin injection current is made to flow from the other end of the first conductive line toward one end, and when making the anti-parallel, the spin injection current is made to be The spin memory according to claim 13 or 14, wherein the flow is performed from one end of the first conductive wire toward the other end.   16. The direction of the spin injection current flowing through the first conductive line and the direction of the spin injection current flowing through the second conductive line are different from each other. Spin memory.   The spin memory according to any one of claims 1 to 16, wherein the switch element is a MISFET.   The spin memory according to any one of claims 1 to 17, wherein at least one of the first and second conductive lines has a yoke structure.   The spin memory according to any one of claims 1 to 18, wherein the second conductive line functions as a bit line and is connected to a sense amplifier.   The spin memory according to claim 1, wherein the first and second conductive lines extend in the same direction.   The spin memory according to claim 1, wherein the first and second conductive lines extend in different directions.   The spin memory according to any one of claims 1 to 21, wherein magnetization reversal by the spin torque is assisted by a magnetic field generated by the spin injection current.   And a second magnetoresistive element disposed between one end of the first conductive line and the third conductive line, wherein the first conductive line includes the second and second conductive lines. The spin memory according to any one of claims 1 to 22, wherein the spin memory is disposed between three conductive lines.   The spin memory of claim 23, wherein the first and second magnetoresistive elements have the same structure.   25. The spin memory according to claim 23, wherein data is independently written in each of the first and second magnetoresistance effect elements.   25. The spin memory according to claim 23, wherein complementary data is written in the first and second magnetoresistance effect elements.   The magnetic material is an alloy selected from the group of Ni-Fe, Co-Fe, and Co-Fe-Ni, (Co, Fe, Ni)-(B), (Co, Fe, Ni)-(B)- (P, Al, Mo, Nb, Mn), Co- (Zr, Hf, Nb, Ta, Ti), an amorphous material selected from the group, and Co-Cr-Fe-Al, Co-Cr-Fe- 27. The spin according to any one of claims 1 to 26, comprising at least one of Heusler materials selected from the group of Si, Co-Mn-Si, and Co-Mn-Al. memory.   A first and second conductive lines; a magnetoresistive effect element disposed between one end of the first conductive line and the second conductive line; and a switch element connected to the other end of the first conductive line; A driver / sinker for passing a spin injection current for magnetization reversal by spin torque to the magnetoresistive effect element through the first and second conductive lines, and an assist for generating a magnetic field to assist magnetization reversal by the spin torque The magnetoresistive element includes a magnetic recording layer having a variable magnetization direction and a magnetic pinned layer to which the magnetization direction is fixed, so that the magnetic recording layer can be easily magnetized. The spin memory characterized in that an angle θ formed by the axis and the major axis of the first conductive line satisfies 0 ° <θ ≦ 45 °.   29. The spin memory according to claim 28, wherein the assist current is cut off before an intermediate point of a period during which the spin injection current is flowing.   30. The spin memory according to claim 28, wherein the second and third conductive lines extend in the same direction.   30. The spin memory according to claim 28, wherein the second and third conductive lines extend in different directions.

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