JP2014049659A - Magnetic memory - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress variation in writing operation of a magnetic memory.SOLUTION: The magnetic memory of an embodiment includes a magnetoresistive effect element comprising a reference layer 14 having a magnetization direction invariable and perpendicular to a film surface, a memory layer 12 having a magnetization direction variable and perpendicular to the film surface, and a nonmagnetic layer 13 arranged between these layers; a side wall protective film 15 covering a side wall of the magnetoresistive effect element present in a direction perpendicular to a lamination direction of the reference layer 14, the memory layer 12, and the nonmagnetic layer 13; and an interlayer insulation film 16 covering the side wall protective film 15. The memory layer 12 has a positive magnetostriction constant, and an internal stress of the memory layer 12 is a compression stress.

Description

  Embodiments relate to a magnetic memory.

  As a magnetic memory, for example, a magnetic random access memory (MRAM) is known.

  In the magnetic random access memory, reducing the variation in the write operation is an indispensable issue for improving the reliability. For this purpose, for example, the coercive force of the storage layer may be increased to improve the magnetization stability of the magnetoresistive effect element (MTJ: Magnetic Tunnel Junction). Generally, in a perpendicular magnetization type MTJ element used in a magnetic random access memory for spin injection writing, the perpendicular magnetic anisotropy of the storage layer is caused by the addition of magnetoelastic energy to the origin, so internal stress and external stress are applied. Then, the anisotropic magnetic field is dispersed, the coercive force of the memory layer is lowered, and the writing operation is varied. Therefore, in order to suppress the variation in the write operation, a technique for stabilizing the magnetization by strictly controlling the internal stress and the external stress applied to the storage layer and maintaining the coercive force of the perpendicular magnetization is required.

JP 2010-165790 A JP 2009-212323 A JP 2007-513501 A JP 2005-327988 A JP 2009-26944 A

  The embodiment proposes a technique for suppressing variation in write operation in a magnetic memory.

  According to the embodiment, the magnetic memory is disposed between the reference layer having a magnetization direction perpendicular to the film surface and an invariable magnetization direction, the storage layer having a magnetization direction perpendicular to the film surface and a variable value, and these layers. A magnetoresistive effect element having a nonmagnetic layer, a side wall protective film covering a side wall of the magnetoresistive effect element in a direction perpendicular to a stacking direction of the reference layer, the storage layer, and the nonmagnetic layer, and the side wall An interlayer insulating film covering the protective film, wherein the storage layer has a positive magnetostriction constant, and the internal stress of the storage layer is a compressive stress. Further, when the storage layer has a negative magnetostriction constant, the internal stress of the storage layer is a tensile stress.

The conceptual diagram of a magnetoresistive effect element. Sectional drawing which shows the structure of a 1st Example. Sectional drawing which shows the structure of a 2nd Example. Sectional drawing which shows the structure of a 3rd Example. Sectional drawing which shows the structure of the modification of a 3rd Example. Sectional drawing which shows the structure of a 4th Example. The graph which shows the perpendicular magnetization coercive force of the memory layer with respect to element size. The circuit diagram which shows the structural example of a magnetic random access memory. Sectional drawing which shows the example of a memory cell.

  Hereinafter, embodiments will be described with reference to the drawings.

[Basic idea]
In a magnetic memory, when the direction of spontaneous magnetization (easy magnetization axis) of a ferromagnetic film used for a storage layer is perpendicular to the film surface (perpendicular magnetization), the variation in write operation becomes the most problematic. For one reason, even when no magnetic field is applied to the memory layer, fluctuations in the direction of the magnetic moment of each atom in the memory layer occur due to the effects of thermal energy and magnetoelastic energy, and the perpendicular magnetization of the entire ferromagnetic material decreases. Therefore, it is considered that the writing operation varies.

  Here, when the storage layer is a perpendicular magnetization film having a positive magnetostriction constant, magnetoelastic energy is applied to the origin of the anisotropic magnetic field of the storage layer. The magnetic field is dispersed and the writing operation varies. Thus, the change of the anisotropic magnetic field through the magnetoelastic energy is called the inverse magnetostriction effect. In a perpendicularly magnetized memory layer having a positive magnetostriction constant, the direction of compressive stress becomes a minor axis due to the inverse magnetostrictive effect, and a tensile stress is generated in a direction perpendicular to the direction of the compressive stress, resulting in a major axis. Magnetization is induced in this direction, and the anisotropic magnetic field is distorted. Therefore, in the case of a perpendicular magnetization storage layer having a positive magnetostriction constant, if the magnetization hard axis of the anisotropic magnetic field is set as the compression direction and the easy magnetization axis is set as the magnetization induction direction of the inverse magnetostriction effect, Can be complemented.

  In the following embodiments, in consideration of the fact that the variation in the write operation is due to the dispersion of the perpendicular magnetization in the storage layer, the write operation is performed by complementing the perpendicular magnetization caused by the inverse magnetostriction effect by strictly controlling the stress applied to the storage layer. To suppress the variation of

  In this way, if variation in the write operation can be suppressed by controlling the stress applied to the storage layer, for example, in a magnetic memory using a magnetoresistive effect element having a perpendicular magnetization storage layer and spin injection writing, the write operation Apart from this variation problem, it is possible to reduce the size of the magnetoresistive effect element, to reduce the magnetization reversal energy (coercive force), and to reduce the write current.

  FIG. 1 shows a magnetoresistive element of a magnetic memory.

  The magnetoresistive effect element 10 includes a base layer 11, a storage layer 12 on the base layer 11, a nonmagnetic layer (tunnel barrier layer) 14 on the storage layer 12, and a reference layer 13 on the nonmagnetic layer 14. . The storage layer 12 has a magnetization direction that is perpendicular to the film surface and variable, and the reference layer 13 has a magnetization direction that is perpendicular to the film surface and unchanged.

  The side wall protective film 15 covers the side wall of the magnetoresistive effect element 10, that is, the side wall of the magnetoresistive effect element 10 in the direction perpendicular to the stacking direction of the memory layer 12, the reference layer 13, and the nonmagnetic layer 14. The interlayer insulating film 16 covers the sidewall protective film 15.

  This structure is a top pin type in which the reference layer 13 is above the storage layer 12, but may alternatively be a bottom pin type in which the reference layer 13 is below the storage layer 12.

  An arrow in the storage layer 12 indicates a magnetization induction direction caused by the inverse magnetostriction effect when a stress is applied to the storage layer 12 in a direction parallel to the film surface, that is, in the direction of the hard axis. The magnetization induction direction is perpendicular to the film surface, that is, the magnetization easy axis and the perpendicular magnetization direction, so that the perpendicular magnetization can be complemented.

  For example, in the case of the storage layer 12 having a positive magnetostriction constant, if the internal stress of the storage layer 12 is a compressive stress, a magnetic moment is induced by the inverse magnetostriction effect, so that the perpendicular magnetization of the storage layer 12 is complemented.

  In the case of the memory layer 12 having a negative magnetostriction constant, if the internal stress of the memory layer 12 is a tensile stress, the perpendicular magnetization is complemented in the direction perpendicular to the film surface.

  The layer in contact with the upper surface and the lower surface of the memory layer 12 may have a laminated structure. However, the external stress received from the interface between the layers in contact with the memory layer 12 is a compressive stress when the memory layer 12 has a positive magnetostriction constant, and a tensile stress when the memory layer 12 has a negative magnetostriction constant.

  According to such a magnetoresistive element structure, the storage layer having a positive or negative magnetostriction constant can complement the perpendicular magnetization by the inverse magnetostriction effect, and therefore, variation in write operation can be suppressed.

  Hereinafter, some embodiments embodying the above-mentioned basic idea will be described.

[Example]
First Embodiment FIG. 2 shows a first embodiment.

  This figure shows a magnetoresistive effect element of a magnetic memory.

  In the figure, the same elements as those in FIG.

  The feature of this example is as follows.

  When the memory layer 12 is a ferromagnetic material having a positive magnetostriction constant, the internal stress is a compressive stress. While the memory layer 12 applies a compressive stress to the sidewall protective film 15 in a direction parallel to the film surface, the sidewall protective film 15 applies the compressive stress received from the memory layer 12 to the memory layer 12 through elastic energy. To do. At this time, the perpendicular magnetization of the storage layer 12 is induced in the direction perpendicular to the film surface by the inverse magnetostrictive effect and complemented.

  When the memory layer 12 is a ferromagnetic material having a negative magnetostriction constant, the internal stress is a tensile stress. The memory layer 12 applies tensile stress to the sidewall protective film 15 in a direction parallel to the film surface, while the sidewall protective film 15 applies tensile stress received from the memory layer 12 to the memory layer 12 through elastic energy. To do. At this time, the perpendicular magnetization of the storage layer 12 is induced in the direction perpendicular to the film surface by the inverse magnetostrictive effect and complemented.

  A typical material having a positive or negative magnetostriction constant is, for example, (Co-Fe) 80 at% -B20 at%, and when Fe in (Co-Fe) is 40 at% or more, a positive magnetostriction constant is obtained. Negative magnetostriction constant at 40at% or less. In the case of Co—Fe, when the Co content is 80 at% or less, a positive magnetostriction constant is obtained. When the Co content is 80 at% or more, a negative magnetostriction constant is obtained. Furthermore, in the case of Ni-Fe, when Ni is 80 at% or less, a positive magnetostriction constant is obtained, and when Ni is 80 at% or more, a negative magnetostriction constant is obtained. In the case of Co-Pd, positive magnetostriction is obtained when Co is 40 at% or more, and negative magnetostriction constant is obtained when it is 80 at% or less.

  In addition, as a composition control of a material having compressive stress, there is a method of adding an element having a large atomic radius to an object having a certain solid density, and since an element having a large atomic radius applies compressive stress to an element having a small atomic radius, An object of a certain solid density becomes a material that exerts a compressive stress. For example, when an element (Ta, W, Pt, Pd, Zr, Hf, Nb) having a larger atomic radius than these is added to a Co alloy, an Fe alloy, or the like, a material having a compressive stress is obtained. On the contrary, when an element having a small atomic radius is added to an object having a certain solid density, a material that exerts a tensile stress is obtained. For example, when a few percent of an element (B, C, N, O, Mg, Al) having a smaller atomic radius than a Co alloy or Fe alloy is added to a Co alloy or Fe alloy, it becomes a material that exerts a tensile stress.

  As a condition for forming a material having a compressive stress, there is a method of forming a film by heating at a substrate temperature of, for example, several hundred degrees C. so as to increase the atomic density of the film. For example, in the case of sputtering, there are methods such as lowering the gas pressure, increasing the deposition rate, applying a bias voltage to the substrate, etc., and in the case of CVD, increasing the gas pressure, atomic layer deposition (AtomicLayer Deposition), When a method such as applying a bias voltage to the substrate is used in the plasma CVD method, a material that exerts a compressive stress can be formed. On the contrary, when the film is formed by cooling the substrate temperature to, for example, 10 ° C. or less so that the atomic density of the film is reduced, a material that exerts tensile stress is obtained. For example, in the case of sputtering, there are methods such as raising the gas pressure and lowering the film formation rate, and in the case of CVD, using a method such as lowering the gas pressure and increasing the exhaust speed causes tensile stress. The material can be deposited.

  As described above, according to the first embodiment, the internal stress of the storage layer 12 can be controlled, so that the perpendicular magnetization of the storage layer 12 can be complemented by the magnetization induction by the inverse magnetostriction effect. Therefore, the coercive force of perpendicular magnetization is increased, and variation in write operation can be suppressed.

Second Embodiment FIG. 3 shows a second embodiment.

  This figure also shows the magnetoresistive element of the magnetic memory.

  In the figure, the same elements as those in FIG.

  In the case of this example, unlike the first example, the internal stress, that is, the compressive stress of the memory layer 12 having a positive magnetostriction constant is caused by the first interface and the second interface existing on the lower surface and the upper surface of the memory layer 12. It is characterized by being induced by the shear stress acting on. In other words, since the side wall of the memory layer 12 is compressed by the shear stress acting on the first interface and the second interface, the memory layer 12 generates a compressive stress in a direction parallel to the film surface via elastic energy. At the same time, a tensile stress is generated in the direction perpendicular to the film surface of the memory layer 12, and the perpendicular magnetization can be supplemented by inducing magnetization due to the inverse magnetostriction effect.

  Further, the internal stress, that is, the tensile stress of the memory layer 12 having a negative magnetostriction constant is induced by shear stress acting on the first interface and the second interface existing on the lower surface and the upper surface of the memory layer 12. . In other words, since the side wall of the memory layer 12 is pulled by the shear stress acting on the first interface and the second interface, the memory layer 12 generates a tensile stress in a direction parallel to the film surface via elastic energy. At the same time, it is possible to complement perpendicular magnetization by inducing magnetization of the inverse magnetostrictive effect.

  The composition control of a material having a positive or negative magnetostriction constant, a material having a compressive stress or a tensile stress, and the film forming conditions are the same as those in the first embodiment, and are therefore omitted.

  As described above, according to the second embodiment, the compressive stress is applied to the memory layer 12 due to the shear stress generated at the interface between the memory layer 12 having a positive magnetostriction constant and the upper and lower adjacent layers. Is applied. Therefore, magnetization is induced in the direction perpendicular to the film surface of the storage layer 12 by the inverse magnetostriction effect, and the perpendicular magnetization can be supplemented. Therefore, for example, a situation in which vertical magnetization is dispersed and variation in write operation does not occur does not occur.

Third Embodiment FIG. 4 shows a third embodiment.

  This figure also shows the magnetoresistive element of the magnetic memory.

  In the figure, the same elements as those in FIG.

  In this example, unlike the first example, the internal stress, that is, compressive stress of the memory layer 12 having a positive magnetostriction constant is induced by the compressive stress of the sidewall protective film 15. This is because the memory layer 12 is pulled in the direction perpendicular to the film surface and the film thickness extends in the direction perpendicular to the film surface due to the internal stress of the sidewall protective film 15, but the volume of the memory layer 12 does not change. , Compressed in a direction parallel to the film surface. That is, the memory layer 12 complements the perpendicular magnetization by the inverse magnetostrictive effect by exerting a compressive stress according to the change in the film thickness.

  In addition, the internal stress, that is, the tensile stress of the memory layer 12 having a negative magnetostriction constant is induced by the tensile stress of the sidewall protective film 15. That is, the memory layer complements the perpendicular magnetization by the inverse magnetostriction effect by exerting a tensile stress corresponding to the change in the film thickness.

Examples of the material of the sidewall protective film 15 include an insulating film such as SiN, SiO ₂ , and SiON. In these insulating films, when Si is rich, it becomes a compressive stress, and when it is O rich or N rich, it becomes a tensile stress. When SiN is used as the sidewall protective film, the internal stress of the sidewall protective film can be adjusted by further oxidizing SiN (the internal stress acts in the direction in which the compressive stress increases due to oxidation). Further, the sidewall protective film may be a single layer or a stacked layer.

  As a modification of the third embodiment, as shown in FIG. 5, when the internal stress of the interlayer insulating film 16, that is, compressive stress is applied to the memory layer 12 having a positive magnetostriction constant via the sidewall protective film 15, As in the third embodiment, compressive stress is induced in the memory layer 12. Therefore, the storage layer 12 can supplement the perpendicular magnetization by the inverse magnetostriction effect.

  When the internal stress of the interlayer insulating film 16 is a tensile stress, when the tensile stress of the interlayer insulating film 16 is applied to the memory layer 12 having a negative magnetostriction constant through the sidewall protective film 15, the tensile stress is applied to the memory layer 12. Is triggered. Therefore, the storage layer 12 can supplement the perpendicular magnetization by the inverse magnetostriction effect.

As a material of the interlayer insulating film 16, there is an insulating film such as SiN, SiO ₂ , SiON, etc., like the sidewall protective film 15.

  The composition control of a material having a positive or negative magnetostriction constant, a material having a compressive stress or a tensile stress, and the film forming conditions are the same as those in the first embodiment, and are therefore omitted.

  As described above, according to the third embodiment, since the internal stress is generated in the memory layer 12 due to the internal stress of the sidewall protective film 15, the perpendicular magnetization is induced by the inverse magnetostrictive effect. Therefore, the variation in the write operation due to the dispersion of the perpendicular magnetization of the storage layer 12 can be reduced.

Fourth Embodiment FIG. 6 shows a fourth embodiment.

  This figure also shows the magnetoresistive element of the magnetic memory.

  In the figure, the same elements as those in FIG.

  In this example, unlike the first example, the internal stress of the memory layer 12 having a positive magnetostriction constant, that is, the compressive stress, is such that the thermal expansion coefficient of the sidewall protective film 15 is smaller than the thermal expansion coefficient of the memory layer 12. Sometimes it is triggered. This is because the thermal expansion coefficient of the memory layer 12 is larger than the thermal expansion coefficient of the side wall protective film 15, so that the memory layer 12 expands and pushes the side wall protective film 15, but is pushed back by the reaction of the side wall protective film 15, As a result, the film is compressed in a direction parallel to the film surface. At this time, the film thickness of the memory layer 12 is pulled in the direction perpendicular to the film surface, and perpendicular magnetization is induced by the inverse magnetostriction effect.

  In addition, the internal stress, that is, the tensile stress of the memory layer 12 having a negative magnetostriction constant is induced when the thermal expansion coefficient of the sidewall protective film 15 is larger than the thermal expansion coefficient of the memory layer 12. That is, a tensile stress is generated inside the storage layer 12 in accordance with the external stress received from the sidewall protective film 15, so that the perpendicular magnetization of the storage layer 12 can be supplemented by the inverse magnetostriction effect.

Examples of the material of the sidewall protective film 15 include an insulating film such as SiN, SiO ₂ , and SiON.

  As a modification of the fourth embodiment, the internal stress, that is, compressive stress, of the memory layer 12 having a positive magnetostriction constant is induced when the thermal expansion coefficient of the interlayer insulating film 16 is smaller than the thermal expansion coefficient of the memory layer 12. There is a feature that is. This is because the thermal expansion coefficient of the memory layer 12 is larger than the thermal expansion coefficient of the interlayer insulating film 16, so that the memory layer 12 expands and pushes the interlayer insulating film 16 through the sidewall protective film 15. Is pushed back through the sidewall protective film 15 as a result of this reaction, and as a result, is compressed in a direction parallel to the film surface. At this time, the film thickness of the memory layer 12 is pulled in the direction perpendicular to the film surface, and perpendicular magnetization is induced by the inverse magnetostriction effect.

  Further, the internal stress, that is, the tensile stress of the memory layer 12 having a negative magnetostriction constant is induced when the thermal expansion coefficient of the interlayer insulating film 16 is larger than the thermal expansion coefficient of the memory layer 12. That is, tensile stress is generated inside the memory layer 12 in accordance with the external stress received from the interlayer insulating film 16 via the sidewall protective film 15, so that the perpendicular magnetization of the memory layer 12 can be supplemented by the inverse magnetostrictive effect.

As a material of the interlayer insulating film 16, there is an insulating film such as SiN, SiO ₂ , SiON, etc., like the sidewall protective film 15.

  The composition of the material for the sidewall protective film 15, the material for the interlayer insulating film 16, the material having a positive or negative magnetostriction constant, the material having a compressive stress or tensile stress, and the film forming conditions are described in the first embodiment. Since it overlaps with, it abbreviate | omits. However, the formation temperature of the sidewall protective film 15 and the interlayer insulating film 16 is, for example, 200 degrees or more.

  Thus, in this example, when the memory layer 12 receives external stress from the sidewall protective film 15 due to the difference between the thermal expansion coefficient of the sidewall protective film 15 and the thermal expansion coefficient of the memory layer 12, the memory layer 12 Internal stress occurs in the direction parallel to the film surface. At the same time, since perpendicular magnetization is induced by the inverse magnetostriction effect in the direction perpendicular to the film surface of the storage layer 12, the perpendicular magnetization of the storage layer 12 is complemented. Therefore, variation in write operation due to dispersion of perpendicular magnetization can be suppressed.

[effect]
FIG. 7 shows the perpendicular magnetization coercivity of the storage layer with respect to the element size of the magnetoresistive effect element. The horizontal axis of the figure is the element size, and the element size increases from the left side to the right side. On the other hand, the vertical axis in the figure is the perpendicular magnetization coercivity of the storage layer, and the perpendicular magnetization coercivity of the storage layer increases from the lower side to the upper side. The white dots indicate the perpendicular magnetization coercivity of the storage layer with respect to the element size when tensile stress is applied to the storage layer having a positive magnetostriction constant to generate tensile stress inside the storage layer. Black dots indicate the perpendicular magnetization coercivity of the storage layer with respect to the element size when compressive stress is applied to the storage layer having a positive magnetostriction constant to generate compression stress inside the storage layer.

  As shown in the figure, when the internal stress of the storage layer is a compressive stress, the perpendicular magnetization coercivity of the storage layer with respect to the element size tends to be larger than when the internal stress of the storage layer is a tensile stress. . In addition, when the internal stress of the memory layer is a compressive stress, variations in the perpendicular magnetization coercivity of the memory layer with respect to the element size tend to be suppressed compared to when the internal stress of the memory layer is a tensile stress.

  As described above, when the storage layer has a positive magnetostriction constant, it is possible to increase the perpendicular magnetization coercivity of the storage layer by using the internal stress of the storage layer as a compressive stress, thereby suppressing variations in the write operation. It is possible.

  The same relationship can be obtained when the memory layer has a negative magnetostriction constant. That is, when the internal stress of the storage layer is a tensile stress, the perpendicular magnetization coercivity of the storage layer with respect to the element size tends to be larger than when the internal stress of the storage layer is a compressive stress. Further, when the internal stress of the storage layer is a tensile stress, the variation in the perpendicular magnetization coercivity of the storage layer with respect to the element size tends to be suppressed compared to the case where the internal stress of the storage layer is a compressive stress.

Application example
A case where the magnetic memory according to the above-described embodiment is applied to a magnetic random access memory will be described.

  Hereinafter, as an example, a 1T1R type memory cell array in which one memory cell includes one magnetoresistive element and one select transistor will be described.

  FIG. 8 shows an example of an equivalent circuit of the 1T1R type memory cell array.

  The memory cell array 17 includes a plurality of memory cells MC arranged in an array. One memory cell MC includes one magnetoresistive element R and one select transistor (FET) SW.

  The magnetoresistive element R and the selection transistor SW are connected in series, one end of which is connected to the first bit line BL1, and the other end is connected to the second bit line BL2. A control terminal (gate terminal) of the selection transistor SW is connected to a word line WL extending in the second direction.

  The first bit line BL1 extends in the first direction, and one end thereof is connected to the bit line driver / sinker 18. The second bit line BL2 extends in the first direction, and one end thereof is connected to the bit line driver / sinker & read circuit 19.

  However, the first bit line BL1 can be modified to be connected to the bit line driver / sinker & read circuit 19 and the second bit line BL2 can be connected to the bit line driver / sinker 18.

  Further, the positions of the bit line driver / sinker 18 and the bit line driver / sinker & readout circuit 19 may be reversed, or both may be arranged at the same position.

  The word line WL extends in the second direction, and one end thereof is connected to the word line driver 20.

  FIG. 9 shows an example of a memory cell.

  The selection transistor SW is disposed in the active area AA in the semiconductor substrate 21. The active area AA is surrounded by the element isolation insulating layer 22 in the semiconductor substrate 21. In this example, the element isolation insulating layer 22 has an STI (Shallow Trench Isolation) structure.

  The selection transistor SW includes source / drain diffusion layers 23 a and 23 b in the semiconductor substrate 21, a gate insulating layer 24 on a channel between them, and a gate electrode 25 on the gate insulating layer 24. The gate electrode 25 functions as the word line WL.

  The interlayer insulating layer 26 covers the selection transistor SW. The upper surface of the interlayer insulating layer 26 is flat, and the lower electrode 27 is disposed on the interlayer insulating layer 26. The lower electrode 27 is connected to the source / drain diffusion layer 23b of the selection transistor SW through the contact plug 28.

  The magnetoresistive effect element R is disposed on the lower electrode 27. The upper electrode 29 is disposed on the magnetoresistive element R. The upper electrode 29 functions as a hard mask when processing the magnetoresistive effect element R, for example.

  The sidewall protective film 15 covers the sidewall of the magnetoresistive element R.

  The interlayer insulating layer 16 is disposed on the sidewall protective film 15 and covers the magnetoresistive effect element R. The upper surface of the interlayer insulating layer 16 is flat, and the first and second bit lines BL1 and BL2 are disposed on the interlayer insulating layer 16. The first bit line BL1 is connected to the upper electrode 29. The second bit line BL2 is connected to the source / drain diffusion layer 23a of the selection transistor SW via the contact plug 30.

  Here, the side surface of the magnetoresistive element R is covered with the sidewall protective film 15. The internal stress of the memory layer of the magnetoresistive effect element R is a compressive stress when it has a positive magnetostriction constant in order to complement the perpendicular magnetization of the memory layer, as shown in the above-described embodiments, and is negative. Is the tensile stress when the magnetostriction constant is. However, as long as the element structure of the magnetoresistive effect element R is such that the perpendicular magnetization of the storage layer is complemented, various forms other than the structures shown in the above-described embodiments can be adopted.

  Further, in the manufacture of the magnetoresistive effect element R, the storage layer and the upper, lower, left and right layers in contact with the storage layer are formed using a known deposition technique so as to adjust the stress applied to the storage layer and complement the perpendicular magnetization of the storage layer. Adjust film conditions and material composition. Here, when patterning the magnetoresistive element R by etching, for example, IBE (Ion beam etching), RIE (Reactive Ion beam etching), or GCIB (Gas cluster Ion beam etching) is used to improve the processing accuracy. Is used.

  Here, when the magnetoresistive element R is patterned by these methods, it is known that a residue as a re-deposition layer is formed on the side wall of the magnetoresistive element R. Therefore, the insulation of the residue, the taper angle of the magnetoresistive effect element R (the angle formed between the film surface and the side surface of each layer in the laminated structure) and the processing conditions (gas type, etc.) are optimized. It is necessary to make it. For the residue, it is also effective to make the size of the storage layer and the size of the reference layer different and pattern them separately.

[Musubi]
According to the embodiment, it is possible to suppress variations in the write operation.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  10, R: magnetoresistive effect element, 11: underlayer, 12: storage layer, 13: reference layer, 14: nonmagnetic layer, 15: sidewall protective film, 16: interlayer insulating film, 17: memory cell array, 18: bit Line driver / sinker, 19: bit line driver / sinker & readout circuit, 20: word line driver, 21: semiconductor substrate, 22: element isolation insulating layer, 23a, 23b: source / drain diffusion layer, 24: gate insulating layer, 25: gate electrode, 26: interlayer insulating layer, 27: lower electrode, 28: contact plug, 29: upper electrode, 30: contact plug, SW: selection transistor (FET), MC: memory cell, BL1: first bit Line, BL2: second bit line, WL: word line, AA: active area

Claims (10)

A magnetoresistive element having a reference layer having a magnetization direction perpendicular to the film surface and an invariable magnetization direction, a storage layer having a magnetization direction perpendicular to the film surface and a variable, and a nonmagnetic layer disposed between these layers; ,
A sidewall protective film that covers a sidewall of the magnetoresistive effect element in a direction perpendicular to the stacking direction of the reference layer, the storage layer, and the nonmagnetic layer;
An interlayer insulating film covering the sidewall protective film,
The storage layer has a positive magnetostriction constant;
The magnetic memory, wherein the internal stress of the memory layer is a compressive stress. The magnetic memory according to claim 1, wherein the storage layer has a composition that itself generates the compressive stress.   The magnetic memory according to claim 1, wherein the compressive stress is generated by a shearing stress generated at an interface between the storage layer and a layer adjacent above and below the storage layer. The magnetic memory according to claim 1, wherein the compressive stress is applied by a compressive stress generated in the sidewall protective film. The magnetic memory according to claim 1, wherein the compressive stress is applied by a compressive stress generated in the interlayer insulating film. A magnetoresistive element having a reference layer having a magnetization direction perpendicular to the film surface and an invariable magnetization direction, a storage layer having a magnetization direction perpendicular to the film surface and a variable, and a nonmagnetic layer disposed between these layers; ,
A sidewall protective film that covers a sidewall of the magnetoresistive effect element in a direction perpendicular to the stacking direction of the reference layer, the storage layer, and the nonmagnetic layer;
An interlayer insulating film covering the sidewall protective film,
The storage layer has a negative magnetostriction constant;
The magnetic memory according to claim 1, wherein the internal stress of the memory layer is a tensile stress. The magnetic memory according to claim 6, wherein the storage layer has a composition that generates the tensile stress by itself.   The magnetic memory according to claim 6, wherein the tensile stress is multiplied by a shear stress generated at an interface between the storage layer and a layer adjacent above and below the storage layer. The magnetic memory according to claim 6, wherein the tensile stress is applied by a tensile stress generated in the sidewall protective film. The magnetic memory according to claim 6, wherein the tensile stress is applied by a tensile stress generated in the interlayer insulating film.

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