JP5104753B2 - Magnetic random access memory and manufacturing method thereof - Google Patents

Description

  The present invention relates to an MRAM (Magnetic Random Access Memory), and more particularly to an MRAM that writes data by reversing magnetization using a spin-polarized current.

  Recently, one of the promising writing methods of MRAM proposed is a spin momentum transfer method in which the magnetization of a magnetic recording layer is reversed by injecting a spin-polarized current into the magnetic recording layer. . In the magnetization reversal by the current magnetic field, the size of the memory cell is reduced and the required current is increased. On the other hand, in the spin injection magnetization reversal method, the size of the memory cell is reduced and the required current is reduced. Therefore, the spin injection magnetization reversal method is considered to be an effective method for realizing a large-capacity MRAM.

  However, when the spin injection magnetization reversal method is applied to a magnetic tunnel junction device, it is necessary to overcome the problem of destruction of the tunnel barrier layer. In order to reverse the magnetization by the spin injection magnetization reversal method, it is currently necessary to inject a spin-polarized current of several mA or more into the magnetic recording layer. However, passing such a large current through the magnetic tunnel junction may cause destruction of the tunnel barrier layer.

  One approach for overcoming such a problem is a technique for causing magnetization reversal by passing a spin-polarized current in the in-plane direction of the magnetic recording layer. Such a technique is disclosed in, for example, Patent Document 1, Patent Document 2, and Patent Document 3. By passing a spin-polarized current in the in-plane direction of the magnetic recording layer, the domain wall of the magnetic recording layer is moved and / or torque is applied to the magnetization of the magnetic recording layer, thereby reversing the magnetization of the magnetic recording layer. it can. The technique of flowing a spin-polarized current in the in-plane direction of the magnetic recording layer eliminates the need for a write current to flow through the tunnel barrier layer, and can effectively avoid the problem of destruction of the tunnel barrier layer.

JP 2005-191032 A JP 2005-123617 A US Pat. No. 6,781,871

  However, one requirement of the MRAM is to reduce the write current value. To this end, it is desirable to further reduce the current required for data writing, that is, magnetization reversal. Therefore, it is desired to develop a technique for reducing the spin-polarized current that flows in the in-plane direction of the magnetic recording layer during the write operation.

  An object of the present invention is to provide a magnetic random access memory that can further reduce the magnitude of a spin-polarized current that flows in the in-plane direction of a magnetic recording layer during a write operation of an MRAM.

  The magnetic random access memory according to the present invention has the following configuration. In the following description, the reference numerals of the drawings are attached, but this is merely for clarifying the correspondence between the description of the claims and the embodiment, and the technical scope of the present invention is as follows. Of course, the invention is not limited to the embodiments disclosed in the drawings.

The magnetic random access memory according to the first aspect of the present application includes a magnetization reversal region (8) having reversible magnetization, and spin-polarized current injection for injecting a spin-polarized current into the magnetization reversal region (8) in an in-plane direction. A magnetic recording layer (1) having regions (9, 10), a magnetization fixed layer (3) having fixed magnetization, and between the magnetization switching region (8) and the magnetization fixed layer (3). A tunnel barrier layer (2) provided. At least a part of the magnetization switching region (8)
(A) a first composite ferromagnetic material obtained by combining a non-oxidized metal ferromagnetic material and an oxide of a nonmagnetic material having an oxide generation energy lower than that of the metal ferromagnetic material;
(B) a second composite ferromagnetic material configured by combining the non-nitrided metal ferromagnetic material and the nonmagnetic material nitride having a lower nitride formation energy than the metal ferromagnetic material; and (C) any one of a third composite ferromagnetic material configured by combining a non-carbonized metal ferromagnetic material and a carbide of a nonmagnetic material whose carbide generation energy is lower than that of the metal ferromagnetic material; Is formed.

  In the magnetic random access memory having such a configuration, the region where the spin-polarized current flows is localized due to the use of the composite ferromagnetic material in the magnetization switching region (8), and the current density of the spin-polarized current is Increases locally. Since the magnetization reversal is likely to occur in the portion where the current density is large, the magnetization reversal can be generated in a part of the magnetization reversal region (8) by locally increasing the current density of the spin-polarized current. When magnetization reversal occurs in a part of the magnetization reversal region (8), magnetization reversal of the entire magnetization reversal region (8) is induced. As a result, by forming the magnetization reversal region (8) with a composite ferromagnetic material The magnetization of the magnetization reversal region (8) can be reversed with a small spin-polarized current.

  As the metal ferromagnetic material, iron (Fe), cobalt (Co), nickel (Ni), gadolinium (Gd), or a ferromagnetic material of an alloy of at least two of these elements is used, and as the nonmagnetic material, , Magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), titanium (Ti), vanadium (V) , Chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium (Ce), yttrium (Y) Preferably, an element material selected from lanthanum (La) or a material composed of two or more of these elements is used. It is.

  The magnetization reversal region (8) is adjacent to the spin-polarized current injection region (9, 10) in the in-plane direction and is composed of a composite ferromagnetic portion (8a) formed of a composite ferromagnetic material, and a composite strength. High MR formed of a metal ferromagnetic material joined to the magnetic part (8a) in a direction perpendicular to the in-plane direction and provided between the composite ferromagnetic part and the tunnel barrier layer (2). It is preferable to include a specific ferromagnetic portion (8b).

  The magnetization reversal region (8) was formed of a composite ferromagnetic portion (8c) formed of a composite ferromagnetic material, and a metal ferromagnetic material joined to the composite ferromagnetic portion in the in-plane direction. It is preferable that the composite ferromagnetic part (8c) is provided between the metal ferromagnetic part (8d) and the spin-polarized current injection region (9, 10).

In this case, it is preferable that at least a part of the tunnel barrier layer (2) is directly joined to the metal ferromagnetic part (8d). In order to realize a high MR ratio, the magnetization switching region (8) is joined to the metal ferromagnetic part (8d) in a direction perpendicular to the in-plane direction, and the metal ferromagnetic part (8d) and the tunnel barrier layer are joined. (2) and a high MR ratio ferromagnetic portion formed of a metal ferromagnet (
More preferably, 8b) is provided.

In another aspect, the magnetic random access memory according to the present invention includes a magnetization reversal region (8) having reversible magnetization, a spin-polarized current injection region (9, 10), a magnetization reversal region (8), and a spin polarization. A magnetic recording layer (1) including a composite material region (17-20) provided between the pole current injection regions (9, 10), a magnetization fixed layer (3) having fixed magnetization, and magnetization A tunnel barrier layer (2) provided between the inversion region (8) and the magnetization fixed layer (3). The spin-polarized current injection region (9, 10) is used to inject a spin-polarized current in the in-plane direction into the magnetization switching region (8) through the composite material region (17-20). The composite material region (17-20)
(A) a first composite material in which a non-oxidized first material and an oxide of a second material whose oxide generation energy is lower than that of the first material are combined;
(B) a second composite material in which a non-nitrided first material and a nitride of a second material whose oxide generation energy is lower than that of the first material are combined; and (c) a non-carbonized first material. It is formed of any one of a third composite material in which one material and a carbide of a second material having an oxide generation energy lower than that of the first material are combined.

  In one aspect of the present invention, the first material is a ferromagnetic material, and the second material is a nonmagnetic material. In this case, as the first material, a ferromagnetic material of iron (Fe), cobalt (Co), nickel (Ni), gadolinium (Gd), or an alloy of at least two of these elements is used, and the second material is used. As magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), titanium (Ti), vanadium (V ), Chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium (Ce), yttrium (Y ), A material of an element selected from lanthanum (La), or a material composed of two or more of these elements is preferably used. Arbitrariness.

  In another aspect of the invention, both the first material and the second material are non-magnetic materials. In this case, as the first material, copper (Cu), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), tantalum (Ta), aluminum (Al), osmium (Os), titanium (Ti), manganese (Mn), rhodium (Rh), iridium (Ir), silicon (Si), germanium (Ge), lead (Pb), gallium (Ga), bismuth (Bi), zinc (Zn), a material of an element selected from antimony (Sb), or a material composed of two or more of these elements is used. As the second material, magnesium (Mg), aluminum ( Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium (Ce), It is preferable to use an element material selected from yttrium (Y) and lanthanum (La), or a material composed of two or more of these elements.

In still another aspect of the present invention, a method for manufacturing a magnetic random access memory of the present invention includes:
Forming first and second spin-polarized current injection regions (9, 10) above the substrate (31);
Forming a composite material film (33) covering the first and second spin polarized current injection regions (9, 10);
Etching back the composite material film (33) to form composite material regions (17-20, 27-30) on the side surfaces of the first and second spin-polarized current injection regions (9, 10); ,
Forming a first ferromagnetic film (34) covering the first and second spin-polarized current injection regions (9, 10) and the composite material region (17-20, 27-30);
Forming an insulating film (35) covering the first ferromagnetic film (34);
Forming a second ferromagnetic film (36) covering the insulating film (35);
Forming a mask (39) positioned between the first and second spin-polarized current injection regions (9, 10) above the second ferromagnetic film (36);
The first ferromagnetic film (34), the insulating film (35), and the second ferromagnetic film (36) are covered with the mask of the insulating film (35) and the second ferromagnetic film (36). And a step of etching so that a portion of the first ferromagnetic film (34) between the first and second spin-polarized current injection regions (9, 10) remains. It has.

The composite material film (33)
(A) a first composite material in which a non-oxidized first material and an oxide of a second material whose oxide generation energy is lower than that of the first material are combined;
(B) a second composite material in which a non-nitrided first material and a nitride of a second material whose oxide generation energy is lower than that of the first material are combined; and (c) a non-carbonized first material. It is formed of any one of a third composite material in which one material and a carbide of a second material having an oxide generation energy lower than that of the first material are combined.

  According to such a method of manufacturing a magnetic random access memory, the composite ferromagnetic portion (8c) is formed at both ends of the magnetization switching region (8), or the magnetization switching region (8) and the spin-polarized current injection region ( 9, 10) can be formed with a memory cell having composite material regions (17-20, 27-30).

  According to the present invention, the magnitude of the spin-polarized current that flows in the in-plane direction of the magnetic recording layer during the write operation of the MRAM can be significantly reduced.

FIG. 1A is a sectional view showing the configuration of the MRAM according to the first exemplary embodiment of the present invention. FIG. 1B is a plan view showing the configuration of the MRAM in FIG. 1A. FIG. 2A is a cross-sectional view showing a fine structure of a magnetization switching region formed of a composite ferromagnetic material. FIG. 2B is a cross-sectional view showing a fine structure of a magnetization switching region formed of a composite ferromagnetic material. FIG. 2C is a cross-sectional view showing the fine structure of the magnetization switching region formed of the composite ferromagnetic material. FIG. 3 is a cross-sectional view showing a path through which a current flows in a magnetization switching region formed of a composite ferromagnetic material. FIG. 4A is a graph showing electrical characteristics of the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film. FIG. 4B is a graph showing the magnetic characteristics of the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film. FIG. 4C is a graph showing the oxidation state of cobalt in the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film. FIG. 5A is a cross-sectional view showing another configuration of the MRAM according to the first exemplary embodiment of the present invention. FIG. 5B is a plan view showing the configuration of the MRAM in FIG. 5A. FIG. 6 is a cross-sectional view showing a configuration of the MRAM according to the second exemplary embodiment of the present invention. FIG. 7A is a sectional view showing another configuration of the MRAM according to the second exemplary embodiment of the present invention. FIG. 7B is a plan view showing the configuration of the MRAM in FIG. 7A. FIG. 7C is a cross-sectional view showing another configuration of the MRAM according to the second exemplary embodiment of the present invention. FIG. 7D is a cross-sectional view showing still another configuration of the MRAM according to the second exemplary embodiment of the present invention. FIG. 8 is a sectional view showing still another configuration of the MRAM according to the second exemplary embodiment of the present invention. FIG. 9A is a cross-sectional view showing the configuration of the MRAM according to the third exemplary embodiment of the present invention. FIG. 9B is a sectional view showing another configuration of the MRAM according to the third exemplary embodiment of the present invention. FIG. 10A is a cross-sectional view showing still another configuration of the MRAM according to the third exemplary embodiment of the present invention. FIG. 10B is a cross-sectional view showing still another configuration of the MRAM according to the third exemplary embodiment of the present invention. FIG. 11A is a cross-sectional view showing a manufacturing process of the MRAM of FIG. 10A. FIG. 11B is a cross-sectional view showing a manufacturing process of the MRAM of FIG. 10A. FIG. 11C is a cross-sectional view showing a manufacturing process of the MRAM of FIG. 10A. FIG. 11D is a cross-sectional view showing a manufacturing step of the MRAM of FIG. 10A. FIG. 11E is a cross-sectional view showing a manufacturing process of the MRAM of FIG. 10A. FIG. 12A is a plan view showing a preferred arrangement of the magnetization switching region and the spin-polarized current injection region. FIG. 12B is a plan view showing another preferred arrangement of the magnetization switching region and the spin-polarized current injection region. FIG. 12C is a cross-sectional view showing a preferred MRAM configuration in the case where the magnetization switching region and the spin-polarized current injection region are arranged as shown in FIG. 12B.

Explanation of symbols

1: Magnetic recording layer 2: Tunnel barrier layer 3: Magnetization fixed layer 4: Antiferromagnetic layer 5: Contact layer 6: Via 7: Wiring 8: Magnetization reversal region 9, 10: Spin polarized current injection region 11, 13: Vias 12, 14: Wiring 15: Lower electrode 16: Upper electrode 17, 18, 27, 28: Composite ferromagnetic region 19, 20, 29, 30: Composite nonmagnetic region 21: Ferromagnetic crystal grains 22: Nonmagnetic Grain boundary part 23: Ferromagnetic crystal grain 24: Nonmagnetic grain boundary part 25: Ferromagnetic crystal grain 26: Ferromagnetic-nonmagnetic composite crystal grain 31: Substrate 32: Insulating layer 33: Composite ferromagnetic film 34: Ferromagnetic Film 35: Insulating film 36: Ferromagnetic film 37: Antiferromagnetic film 38: Metal conductive film 39: Mask 41: Via 42: Wiring

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same or similar components are denoted by the same reference numerals, and detailed description thereof is omitted.

(First embodiment)
FIG. 1A is a cross-sectional view showing the configuration of the memory cell 100 of the MRAM according to the first embodiment of the present invention, and FIG. 1B is a plan view showing the configuration of the memory cell 100. As shown in FIG. 1A, a memory cell 100 includes a magnetic recording layer 1, a tunnel barrier layer 2, a magnetization fixed layer 3, an antiferromagnetic layer 4, and a contact layer 5 that are sequentially stacked. I have.

  The magnetic recording layer 1 includes a magnetization reversal region 8 and spin-polarized current injection regions 9 and 10. The magnetization switching area 8 is an area for storing 1-bit data as the magnetization direction. As shown in FIG. 1B, the magnetization switching region 8 has a long shape in the x-axis direction, and the magnetization of the magnetization switching region 8 is directed parallel to the x-axis direction. The magnetization switching region 8 is formed of a magnetically soft ferromagnetic material, and the magnetization of the magnetization switching region 8 can be switched. In the present embodiment, the state where the magnetization direction of the magnetization switching region 8 is the + x direction is associated with the data “1”, and the state where the magnetization direction of the magnetization switching region 8 is the −x direction is the data “0”. Is associated with.

  The spin-polarized current injection regions 9 and 10 are regions used for injecting a spin-polarized current into the magnetization switching region 8 in the in-plane direction, and both are formed of a ferromagnetic material. The spin-polarized current injection regions 9 and 10 are joined to both ends of the magnetization switching region 8. The spin-polarized current injection regions 9 and 10 are adjacent to the magnetization switching region 8 in the x-axis direction and have a long shape in the x-axis direction as shown in FIG. 1B. The magnetization directions of the spin-polarized current injection regions 9 and 10 are all fixed toward the direction toward the magnetization switching region 8. Specifically, the magnetization of the spin-polarized current injection region 9 is fixed toward the + x direction, and the magnetization of the spin-polarized current injection region 10 is fixed toward the −x direction. Instead, the magnetization directions of the spin-polarized current injection regions 9 and 10 may be fixed toward the direction away from the magnetization switching region 8. In this case, the magnetization of the spin-polarized current injection region 9 is fixed toward the −x direction, and the magnetization of the spin-polarized current injection region 10 is fixed toward the + x direction. The spin polarized current injection region 9 is connected to the wiring 12 through the via 11, and the spin polarized current injection region 10 is connected to the wiring 14 through the via 13.

Referring to FIG. 1A, tunnel barrier layer 2 is a thin insulating layer for allowing a tunnel current to flow between magnetization switching region 8 and magnetization fixed layer 3. The tunnel barrier layer 2 is typically formed of aluminum oxide (AlO _x ) or magnesium oxide (MgO).

  The magnetization fixed layer 3 is a ferromagnetic layer whose magnetization is fixed. The magnetization fixed layer 3 is a magnetically hard ferromagnet, and is made of, for example, CoFe. As shown in FIG. 1B, the magnetization fixed layer 3 has a shape that is long in the x-axis direction, and the magnetization of the magnetization fixed layer 3 is oriented in the −x direction. The magnetization switching region 8, the tunnel barrier layer 2, and the magnetization fixed layer 3 constitute a magnetic tunnel junction (MTJ), and the resistance of the magnetic tunnel junction is relative to the magnetization of the magnetization switching region 8 and the magnetization fixed layer 3. Depends on direction.

  Referring to FIG. 1A again, the antiferromagnetic layer 4 is formed of an antiferromagnetic material such as IrMn, and fixes the magnetization of the magnetization fixed layer 3 by exerting an exchange interaction with the magnetization fixed layer 3. . The contact layer 5 provides an electrical connection to the magnetization fixed layer 3 and the antiferromagnetic layer 4 and has a role of protecting the magnetization fixed layer 3 and the antiferromagnetic layer 4 in the manufacturing process. The contact layer 5 is typically made of tantalum. The contact layer 5 is connected to the wiring 7 through the via 6.

  Data writing to the magnetization switching region 8 is performed by injecting a spin polarization current from the spin polarization current injection region 9 or 10 into the magnetization switching region 8. When data “1” is written, a voltage is applied between the wiring 12 and the wiring 14 so that a current flows from the wiring 12 to the wiring 14, that is, a current flows in the magnetic recording layer 1 in the + x direction. Thereby, a spin-polarized current is injected into the magnetization switching region 8 from the spin-polarized current injection region 9 (the magnetization is fixed in the + x direction). The domain wall of the magnetization switching region 8 is pushed in the + x direction by the injected spin-polarized current, or torque is applied to the magnetization, and the magnetization of the magnetization switching region 8 is directed in the + x direction. As a result, data “1” is written to the magnetic recording layer. On the other hand, when data “0” is written, a spin-polarized current is injected from the spin-polarized current injection region 10 (whose magnetization is fixed in the −x direction) into the magnetization switching region 8. Thereby, the magnetization in the magnetization switching region 8 is directed in the −x direction.

  The TMR effect is used to read data stored in the magnetization switching region 8. The resistance of the magnetic tunnel junction composed of the magnetization switching region 8, the tunnel barrier layer 2, and the magnetization fixed layer 3 depends on the relative directions of magnetization of the magnetic recording layer 1 and the magnetization fixed layer 3 due to the TMR effect. When the magnetization of the magnetization switching region 8 and the magnetization fixed layer 3 is anti-parallel, the magnetic tunnel junction exhibits a relatively high resistance, and the magnetization of the magnetization switching region 8 and the magnetization fixed layer 3 is parallel. The magnetic tunnel junction exhibits a relatively low resistance. Data stored in the magnetic recording layer 1 is identified by detecting a change in resistance of the magnetic tunnel junction. The change in resistance of the magnetic tunnel junction is generated in the magnetic tunnel junction by applying a predetermined voltage to the magnetic tunnel junction and measuring a current flowing in the magnetic tunnel junction, or by flowing a predetermined current in the magnetic tunnel junction. It can be identified by measuring the voltage.

  One feature of the memory cell 100 of the first embodiment is that the magnetization switching region 8 of the magnetic recording layer 1 includes a metal ferromagnetic material such as NiFe and CoFe, and an oxide and a nitridation, respectively, than the metal ferromagnetic material. And a composite ferromagnetic material composed of a composite of an oxide, carbide, or nitride of a non-magnetic material with low energy and carbide generation energy. The metal ferromagnetic material exists in the magnetization switching region 8 in a state where at least a part thereof is not oxidized, carbonized, or nitrided. If the entire metal ferromagnetic material is oxidized, carbonized, or nitrided, the magnetization switching region 8 loses ferromagnetism and loses conductivity, which is not preferable. By mixing a non-magnetic material that is more easily oxidized, nitrided, and carbonized than a metal ferromagnetic material into the composite ferromagnetic material, the non-magnetic material can be selectively (or preferentially) oxidized, nitrided, or carbonized. .

Specifically, the magnetization switching region 8 is made of a material whose composition formula is represented by F _M MO _x , F _M MN _x , or F _M MC _x . Here, F _M is meant a metallic ferromagnetic material. On the other hand, M means a material composed of an element having an oxide generation energy lower than that of the metal ferromagnet F _M for F _M MO _x , and nitride generation than that of the metal ferromagnet F _M for F _M MN _x. It means a material made of an element having a low energy, and F _M MC _x means a material made of an element having a lower carbide generation energy than the metal ferromagnet F _M.

As the metal ferromagnetic material _{F M} is iron (Fe), cobalt (Co), nickel (Ni), gadolinium (Gd), or those of at least two elements of the alloy (e.g., CoFe, NiFe) can be employed.

  On the other hand, as the nonmagnetic material M, magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium A material of an element selected from (Ce), yttrium (Y), and lanthanum (La), or a material composed of two or more of these elements can be used. As the material M, tantalum, zirconium, hafnium, aluminum, magnesium, titanium, lithium, silicon, niobium, and the like are more easily oxidized, nitrided, and carbonized as compared with ferromagnetic elements. Since insulation is also high, it is particularly suitable.

2A to 2C are conceptual diagrams showing a fine structure that the magnetization switching region 8 formed of a composite ferromagnetic material can take. When the composition of the non-magnetic material M is relatively small, the magnetization reversal region 8, the ferromagnetic crystal grains 21 is a columnar crystal made of a metal ferromagnetic F _M, MO x present in the grain _boundaries, MN _It has a fine structure composed of nonmagnetic grain boundary portions 22 formed of _x or MC _x . On the other hand, when the composition of the nonmagnetic material M is relatively large, the magnetization switching region 8 has a structure corresponding to the atomic radius of the elements constituting the material M. If the atomic radius of elements constituting the non-magnetic material M is smaller than the atomic radius of the element forming the metal ferromagnetic F _M, as shown in Figure 2B, the magnetization reversal region 8, metal the ferromagnetic crystal grains 23 is a granular crystals formed in the ferromagnetic body F _M, which is configured on that present in the grain boundary MO _x, MN _x, or a non-magnetic grain boundary portions 24 formed by MC _x Has a fine structure. On the other hand, the atomic radius of elements constituting the material M is greater than the atomic radius of the element forming the metal ferromagnetic F _M is a columnar crystal formed only of a metal ferromagnetic F _M ferromagnetic It composed of a non-magnetic composite grain 26 - the crystal grains 25, oxide of metal ferromagnetic F _M and the material M, a nitride, or formed of carbides ferromagnetic. Even if taking any of these microstructures, the magnetization inversion region 8 has a crystal grain which is formed of a metal ferromagnetic F _M.

2A to 2C, by using a composite ferromagnetic material in the magnetization switching region 8, the region where the spin-polarized current flows is localized, and the current density of the spin-polarized current is obtained. Increases locally. This makes it possible to reverse the magnetization of the magnetization switching region 8 with a small current. For example, the magnetization reversal region 8, as shown in Figure 2B, the ferromagnetic crystal grains 23 formed of a metal ferromagnetic _{F M, MO} x present in the grain boundaries, MN _x, or MC _x As shown in FIG. 3, the spin-polarized current is caused by the adjacent ferromagnetic crystal grains 23 having a fine structure composed of the nonmagnetic grain boundary portions 24 formed by Only the part in contact flows selectively. This is because the nonmagnetic grain boundary 24 formed of an oxide, nitride, or carbide is an insulator and thus has a large electric resistance. Therefore, by using a composite ferromagnetic material for the magnetization switching region 8, the region where the spin-polarized current flows is localized, and the current density of the spin-polarized current increases locally. Since the magnetization reversal is likely to occur in the portion where the current density is large, the magnetization reversal can be generated in a part of the magnetization reversal region 8 by locally increasing the current density of the spin-polarized current. When magnetization reversal occurs in a part of the magnetization reversal region 8, magnetization reversal of the entire magnetization reversal region 8 is induced. As a result, the magnetization reversal region 8 formed of the composite ferromagnetic material has a small spin polarization current. Magnetization can be reversed.

In addition, the use of the composite ferromagnetic material for the magnetization switching region 8 has the effect of reducing the switching magnetic field Hc necessary for switching the magnetization of the magnetization switching region 8 and reducing the current required for writing. The magnetic recording layer formed of a composite ferromagnetic material, an oxide of a non-magnetic material M, nitrides, or by carbides are present, the crystal grains are separated which is formed by a metal ferromagnetic F _M, grain The particle size of the particle becomes smaller. As known to those skilled in the art, the particle size of (the magnetization in the range inversion region 8 expresses ferromagnetic entirety) metal ferromagnetic F _M of the crystal grains is small, also becomes small inverted magnetic field Hc. As the reversal magnetic field Hc becomes smaller, the magnetization of the magnetization reversal region 8 is easily reversed, and the current required for writing is also reduced.

In one embodiment, the magnetization reversal region 8, as a metal ferromagnetic _{F M} CoFe, a non-magnetic material M as Ta is a composite ferromagnetic material used _{(Co 90 Fe 10) 85 Ta} 15 O x film Can be configured. By optimizing the manufacturing conditions, it is possible to form a (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film in which only Ta is selectively oxidized, and such (Co ₉₀ Fe ₁₀ ) ₈₅ can be formed. The Ta ₁₅ O _x film can be suitably used as a composite ferromagnetic material constituting the magnetization switching region 8.

The inventor created a (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film and measured its electrical and magnetic properties. The (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film was formed by reactive sputtering using a sputtering gas in which argon gas and oxygen gas were mixed. As a target material, (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x was used. The (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film was produced by varying the partial pressure of oxygen gas in the sputtering gas, and the electrical and magnetic properties of the produced (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film Characteristics were measured. The partial pressure of oxygen gas was adjusted by the flow rate ratio rO ₂ / Ar of oxygen gas to argon gas. Here, the flow rate ratio rO ₂ / Ar of the oxygen gas is expressed by the following formula where the flow rate of oxygen gas in the sputtering gas is [O ₂ ] (sccm) and the flow rate of argon gas is [Ar] (sccm):
rO ₂ / Ar = [O ₂ ] / [Ar],
Is a parameter defined by

4A to 4C are graphs showing the electrical and magnetic characteristics of the measured (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film. When the flow rate ratio rO ₂ / Ar of the oxygen gas becomes 0.2 or more, as shown in FIG. 4A, the specific resistance of the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film increases rapidly, As shown in FIG. 4B, the saturation magnetization decreases rapidly. As a result, when the flow ratio rO ₂ / Ar of the oxygen gas is less than 0.2, only Ta is selectively oxidized and Co ₉₀ Fe ₁₀ is not oxidized (Co ₉₀ Fe ₁₀ ) ₈₅ Ta. _This suggests that it is present in the ₁₅ O _x film. This was supported by examining the oxidation state of cobalt contained in the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film by XPS (X-ray photoelectron analysis). FIG. 4C is a graph showing the Co2p spectrum result obtained by XPS. In the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film produced under the condition that the flow rate ratio rO ₂ / Ar of the oxygen gas is 0.13, a peak of photoelectron intensity is observed at the binding energy corresponding to metallic cobalt Co. It was. On the other hand, in the (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film produced under the condition that the flow rate ratio rO ₂ / Ar of the oxygen gas is 0.54, the photoelectron intensity peak is obtained at the binding energy corresponding to cobalt oxide CoO. It was observed. This indicates that when the flow rate ratio rO ₂ / Ar of oxygen gas is less than 0.2, only Ta is selectively oxidized and Co is not oxidized. The (Co ₉₀ Fe ₁₀ ) ₈₅ Ta ₁₅ O _x film in which only Ta is selectively oxidized can be used as a composite ferromagnetic material constituting the magnetization switching region 8.

  In the memory cell 100 shown in FIG. 1A, the tunnel barrier layer 2, the magnetization fixed layer 3, and the antiferromagnetic layer 4 are formed on the magnetic recording layer 1, but as shown in FIG. 5A. In addition, the magnetic recording layer 1 can be formed on the laminate of the antiferromagnetic layer 4, the magnetization fixed layer 3, and the tunnel barrier layer 2. Specifically, in the memory cell 100A of FIG. 5A, the antiferromagnetic layer 4, the magnetization fixed layer 3, and the tunnel barrier layer 2 are sequentially formed on the lower electrode 15, and the magnetization switching region 8 further includes a tunnel barrier layer. The magnetic recording layer 1 is formed on the tunnel barrier layer 2 so as to be joined to the magnetic barrier layer 2. An upper electrode 16 is joined on the magnetization switching region 8.

  In the memory cell 100A configured as described above, as in the memory cell 100 of FIG. 1A, data writing to the magnetization switching region 8 is performed by spin polarization from the spin polarization current injection region 9 or 10 to the magnetization switching region 8. This is done by injecting current. On the other hand, the data stored in the magnetization switching region 8 is read by applying a predetermined voltage between the lower electrode 15 and the upper electrode 16 to detect a current flowing in the magnetic tunnel junction, thereby detecting the magnetic tunnel junction. This is done by identifying the resistance. The resistance of the magnetic tunnel junction may be identified by detecting a voltage generated in the magnetic tunnel junction by passing a predetermined current between the lower electrode 15 and the upper electrode 16.

(Second Embodiment)
One problem with configuring the magnetization switching region 8 with the above-described composite ferromagnetic material is that the composite ferromagnetic material is essentially inferior in crystallinity, and therefore the magnetization switching region 8, the tunnel barrier layer 2, the magnetization fixed layer 3, and the like. The MR ratio of the magnetic tunnel junction constituted by This is not preferable because the S / N ratio during the read operation is lowered. In the second embodiment, a technique for improving the MR ratio of the magnetic tunnel junction is provided.

  FIG. 6 is a cross-sectional view showing a configuration of an MRAM memory cell 100B according to the second embodiment of the present invention. In the memory cell 100B of FIG. 6, the magnetization switching region 8 of the magnetic recording layer 1 includes a composite ferromagnetic portion 8a and a high MR ratio ferromagnetic portion 8b formed on the composite ferromagnetic portion 8a. The composite ferromagnetic portion 8a is formed of the composite ferromagnetic material described in the first embodiment. On the other hand, the high MR ratio ferromagnetic layer 8b is formed of a metal ferromagnetic material exhibiting a high MR ratio, preferably CoFe or CoFeB. The tunnel barrier layer 2 is formed on the high MR ratio ferromagnetic portion 8b. When the tunnel barrier layer 2 is formed of a magnesium oxide film (MgO), it is particularly preferable that the high MR ratio ferromagnetic layer 8b is formed of amorphous CoFeB. By forming the high MR ratio ferromagnetic layer 8b with amorphous CoFeB, the crystallinity of the MgO film formed as the tunnel barrier layer 2 thereon can be improved.

  In the memory cell 100B of FIG. 6, the magnitude of the spin-polarized current necessary for reversing the magnetization switching region 8 is largely governed by the composite ferromagnetic portion 8a, and the MR ratio of the magnetic tunnel junction is generally high MR ratio ferromagnetic. Note that if the magnetization of the composite ferromagnetic portion 8a is reversed, the magnetization of the high MR ratio ferromagnetic portion 8b directly joined thereto is also reversed. Therefore, the memory cell 100B illustrated in FIG. 6 can simultaneously achieve a reduction in spin-polarized current necessary for writing and an improvement in the MR ratio of the magnetic tunnel junction.

  As shown in FIGS. 7A and 7B, it is also preferable that the magnetization switching region 8 is composed of a composite ferromagnetic portion 8c and a metal ferromagnetic portion 8d. The composite ferromagnetic part 8c is formed of the above-described composite ferromagnetic material, and the metal ferromagnetic part 8d is a metal ferromagnetic substance (expressing a higher MR ratio than the composite ferromagnetic material), for example, NiFe, CoFe, It is made of CoFeB. The composite ferromagnetic portion 8 c is provided at both ends of the magnetization switching region 8. In other words, the composite ferromagnetic part 8c is joined to both ends of the metal ferromagnetic part 8d. The tunnel barrier layer 2 is formed on the metal ferromagnetic portion 8d.

  Even with such a configuration, it is possible to simultaneously reduce the spin-polarized current required for writing and improve the MR ratio of the magnetic tunnel junction. The reversal of the magnetization of the metal ferromagnetic portion 8d directly bonded thereto is induced by the reversal of the magnetization of the composite ferromagnetic layer 8c. Therefore, in the configuration of FIG. 6B, it is necessary to reverse the magnetization reversal region 8. The magnitude of the spin-polarized current is largely governed by the composite ferromagnetic layer 8c. On the other hand, the MR ratio of the magnetic tunnel junction is generally governed by the metal ferromagnetic portion 8d that is higher than that of the composite ferromagnetic material. Accordingly, the MR ratio of the magnetic tunnel junction is effectively improved while the spin-polarized current required for writing is effectively reduced.

  The position where the composite ferromagnetic part 8 c is provided is not limited to both ends of the magnetization switching region 8. As shown in FIG. 7C, as long as at least a part of the tunnel barrier layer 2 is joined to the metal ferromagnetic portion 8d, the composite ferromagnetic portion 8c is provided at an intermediate position of the magnetization switching region 8. Is also possible. Further, as shown in FIG. 7D, the combined ferromagnetic part 8 c can be provided only at one end of the magnetization switching region 8.

  However, the configuration in which the composite ferromagnetic portion 8c is provided at both ends of the magnetization switching region 8 is preferable in the following points. First, since the composite ferromagnetic part 8 c is provided at both ends of the magnetization switching region 8, the domain wall can be moved first at both ends of the magnetization switching region 8 at the time of magnetization switching. This effectively suppresses the occurrence of a plurality of domains in the magnetization switching region 8. Secondly, the configuration in which the composite ferromagnet portion 8c is provided at both ends of the magnetization switching region 8 makes it possible to pin the domain wall at both ends of the magnetization switching region 8 and stabilize the domain wall. In order to operate the MRAM stably, it is required that the domain wall movement at the time of writing does not affect the spin-polarized current injection regions 9 and 10 where the magnetization should be fixed. The configuration in which the composite ferromagnet portion 8 c is provided at both ends of the magnetization switching region 8 weakens the magnetic coupling between the magnetization switching region 8 and the spin-polarized current injection regions 9, 10, Pin the domain wall at both ends. For this reason, the movement of the domain wall is prevented from spreading to the spin-polarized current injection regions 9 and 10, and the operation of the MRAM is made more stable.

  As shown in FIG. 8, it is also preferable that the magnetization switching region 8 includes a high MR ratio ferromagnetic portion 8b in addition to the composite ferromagnetic portion 8c and the metal ferromagnetic portion 8d. . The high MR ratio ferromagnetic part 8b is formed on the metal ferromagnetic part 8d, and the tunnel barrier layer 2 is formed on the high MR ratio ferromagnetic part 8b. The high MR ratio ferromagnetic layer 8b is formed of a metal ferromagnetic material that exhibits a high MR ratio, preferably CoFe or CoFeB. Such a configuration is suitable for further improving the MR ratio of the magnetic tunnel junction.

(Third embodiment)
FIG. 9A is a cross-sectional view showing the configuration of the memory cell 100D according to the third embodiment of the present invention. In the present embodiment, the magnetization switching region 8 is formed of a metal ferromagnet such as NiFe, while the composite ferromagnet region 17 is interposed between the magnetization switching region 8 and the spin-polarized current injection regions 9 and 10. , 18 are provided. The composite ferromagnetic regions 17 and 18 are formed of the composite ferromagnetic material described in the first embodiment.

  Unlike the composite ferromagnetic material portion 8c of the magnetization switching region 8 of the second embodiment, the composite ferromagnetic material regions 17 and 18 are formed so as not to cause reversal of their own magnetization. The magnetization of the composite ferromagnetic region 17 is fixed in the same direction as the magnetization of the spin-polarized current injection region 9, and the magnetization of the composite ferromagnetic region 18 is the same as the magnetization of the spin-polarized current injection region 10. Fixed to.

  The memory cell 100D having such a configuration does not promote the reversal of the magnetization reversal region 8 by easily reversing the magnetization of the composite ferromagnetic regions 17 and 18. However, the composite ferromagnetic regions 17 and 18 localize the spin-polarized current injected into the magnetization switching region 8, thereby localizing the current density of the spin-polarized current injected into the magnetization switching region 8. Increase it. Therefore, by providing the composite ferromagnetic regions 17 and 18, the magnitude of the spin-polarized current necessary for reversing the magnetization of the magnetization switching region 8 can be reduced. In addition, since the magnetization switching region 8 is formed of a metal ferromagnetic layer, a high MR ratio can be realized.

  As shown in FIG. 9B, instead of the composite ferromagnetic regions 17 and 18, composite nonmagnetic regions 19 and 20 may be provided. The composite non-magnetic regions 19 and 20 include a first non-magnetic material and an oxide, a carbide, and a second non-magnetic material having lower energy for generating oxide, nitride, and carbide than the first non-magnetic material, respectively. Alternatively, it is made of a composite nonmagnetic material composed of nitride and composite. The first nonmagnetic material is present in the composite ferromagnetic regions 17 and 18 in a state in which at least a part thereof is not oxidized, carbonized, or nitrided. If all of the first nonmagnetic material is oxidized, carbonized, or nitrided, the composite ferromagnetic regions 17 and 18 lose conductivity, which is not preferable. The second nonmagnetic material is selectively (or preferentially) oxidized by mixing the second nonmagnetic material, which is more easily oxidized, nitrided, and carbonized than the first nonmagnetic material, into the composite nonmagnetic material. It can be nitrided or carbonized.

Specifically, the composite nonmagnetic regions 19 and 20 are made of a material whose composition formula is represented by N _M MO _x , N _M MN _x , or N _M MC _x . Here, N _M is mean first non-magnetic material. Meanwhile, M is, N _M MO For _x means the second non-magnetic material consisting of lower element oxide formation energy than the first non-magnetic material N _M, for N _M MN _x first non means a magnetic material N material formed of a nitride formation energy is lower element than _M, it means a material consisting of carbide formation energy is lower element than the first non-magnetic material N _M for N _M MC _x .

  As the first nonmagnetic material NM, copper (Cu), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), tantalum (Ta), aluminum (Al), Osmium (Os), titanium (Ti), manganese (Mn), rhodium (Rh), iridium (Ir), silicon (Si), germanium (Ge), lead (Pb), gallium (Ga), bismuth (Bi), A material of an element selected from zinc (Zn) and antimony (Sb), or a material composed of two or more of these elements may be used. On the other hand, as the second nonmagnetic material M, magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca ), Titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), molybdenum (Mo), cerium (Ce) ), Yttrium (Y) and lanthanum (La), or a material composed of two or more of these elements may be used. These materials are particularly easily oxidized, nitrided, and carbonized among nonmagnetic elements.

  By using the composite nonmagnetic regions 19 and 20 formed of such a composite nonmagnetic material, the spin-polarized current injected into the magnetization switching region 8 is localized, whereby the magnetization switching region 8 It is possible to locally increase the current density of the spin-polarized current injected into the. Therefore, by providing the composite non-magnetic regions 19 and 20, the magnitude of the spin-polarized current necessary for reversing the magnetization of the magnetization switching region 8 can be reduced. In addition, since the magnetization switching region 8 is formed of a metal ferromagnetic layer, a high MR ratio can be realized.

  FIG. 10A is a cross-sectional view showing a more realistic structure of the memory cell 100D in which the composite ferromagnetic regions 17 and 18 are provided. A memory cell 100D of FIG. 10A includes a composite ferromagnetic region 17 provided between the magnetization switching region 8 and the spin-polarized current injection region 9, and the magnetization switching region 8 of the spin-polarized current injection region 9 and A composite ferromagnetic region 27 is provided at the opposite end. Furthermore, in addition to the composite ferromagnetic region 18 being provided between the magnetization switching region 8 and the spin-polarized current injection region 10, the composite is formed at the end opposite to the magnetization switching region 8 of the spin-polarized current injection region 10. A ferromagnetic region 28 is provided.

  11A to 11E are cross-sectional views illustrating a preferred manufacturing process for forming the memory cell 100D of FIG. 10A. First, as shown in FIG. 11A, wirings 12 and 14 and vias 11 and 13 are formed in an insulating layer 32 covering the substrate 31, and a spin-polarized current injection region is further formed on the insulating layer 32. 9, 10 are formed. The spin-polarized current injection regions 9 and 10 are formed by forming a ferromagnetic film on the entire surface of the insulating layer 32 and then patterning the formed ferromagnetic film by photolithography.

  Subsequently, as shown in FIG. 11B, a composite ferromagnetic film 33 formed of the above-described composite ferromagnetic material is formed on the entire surface of the insulating layer 32. The width of the composite ferromagnetic material regions 17 and 18 to be finally formed can be easily and precisely controlled in nanometer units by the film thickness formed at this time. This is a practical advantage of the present forming method.

  After the formation of the composite ferromagnetic film 33, as shown in FIG. 11C, the entire surface is etched back. By the entire surface etchback, the composite ferromagnetic film 33 is selectively left only on the side surfaces of the spin-polarized current injection regions 9 and 10 to form composite ferromagnetic regions 17, 18, 27, and 28.

  Subsequently, as shown in FIG. 11D, a ferromagnetic film 34, an insulating film 35, a ferromagnetic film 36, an antiferromagnetic film 37, and a metal conductive film 38 are sequentially formed. As will be described later, the ferromagnetic film 34, the insulating film 35, the ferromagnetic film 36, the antiferromagnetic film 37, and the metal conductive film 38 are respectively formed into the magnetization switching region 8, the tunnel barrier layer 2, and the magnetization by a subsequent process. A film processed into the fixed layer 3, the antiferromagnetic layer 4, and the contact layer 5.

After the formation of the ferromagnetic film 34, the insulating film 35, the ferromagnetic film 36, the antiferromagnetic film 37, and the metal conductive film 38, as shown in FIG. 11E, the tunnel barrier layer 2, the magnetization fixed layer 3, A mask 39 that covers portions corresponding to the antiferromagnetic layer 4 and the contact layer 5 is formed by photolithography. Subsequently, by performing etching using the mask 39, the insulating film 35, the ferromagnetic film 36, the antiferromagnetic film 37, and the metal conductive film 38 are patterned, and the magnetization fixed layer 3, the antiferromagnetic layer 4, and Contact layer 5 is formed. In addition, the magnetization reversal region 8 is formed by etching the ferromagnetic film 34 so that only the portion of the ferromagnetic film 34 between the composite ferromagnetic regions 17 and 18 remains selectively. By such a manufacturing process, the memory cell 100D shown in FIG. 10A is formed. Further, the entire surface may be planarized by CPM (Chemical Mechanical Polishing) or the like before the mask 39 is formed. In that case, the amount of the remaining film to be etched is more uniform throughout the device, which is preferable because the bonding portion can be formed with higher accuracy.

  Since the memory cell 100C illustrated in FIG. 7A and the memory cell 100D illustrated in FIG. 9A have the same structure, the above manufacturing process is applied to the formation of the memory cell 100C illustrated in FIG. 7A. It will be obvious to those skilled in the art that this is possible.

If a composite nonmagnetic film made of the composite nonmagnetic material is formed instead of the composite ferromagnetic film 33, the composite nonmagnetic regions 19 and 20 are provided by the same manufacturing process. The memory cell 100D can be formed. In this case, as shown in FIG. 10B, the composite non-magnetic region 2 at the end opposite to the magnetization switching region 8 of the spin-polarized current injection region 9.
9 and a composite nonmagnetic material region 30 is provided at the end of the spin-polarized current injection region 10 opposite to the magnetization switching region 8.

  In any of the first to third embodiments, the geometrical arrangement of the magnetization switching region 8 and the spin-polarized current injection regions 9 and 10 in the magnetic recording layer 1 is as shown in FIG. However, the present invention is not limited to the arrangement in which the magnetization switching region 8 and the spin-polarized current injection regions 9 and 10 are aligned. For example, as shown in FIG. 12A, the magnetization reversal region 8 can be formed long in the x-axis direction, while the spin-polarized current injection regions 9 and 10 can be formed long in the y-axis direction. is there. In this case, the magnetizations of the spin-polarized current injection regions 9 and 10 are all fixed in the + y direction. Instead, the magnetizations of the spin-polarized current injection regions 9 and 10 can all be fixed in the −y direction. In such a configuration, since the magnetization directions of the spin-polarized current injection regions 9 and 10 are the same, it is easy to direct the magnetization of the spin-polarized current injection regions 9 and 10 in a desired direction in the manufacturing process. . It should be noted that in the configuration of FIG. 1B, the magnetization directions of the spin-polarized current injection regions 9 and 10 are reversed.

  Further, as shown in FIG. 12B, both of the spin-polarized current injection regions 9 and 10 can be connected to one end of the magnetization switching region 8. In the configuration of FIG. 12B, the spin-polarized current injection region 9 is formed long in the + S direction, which forms an angle of 120 ° counterclockwise with respect to the + x direction, and the spin-polarized current injection region 10 is formed in the + x direction. And formed long in the + T direction, which forms an angle of 120 ° clockwise. The magnetization M1 of the spin-polarized current injection region 9 is directed in the -S direction (that is, the direction away from the magnetization switching region 8), and the magnetization M2 of the spin-polarized current injection region 10 is the + T direction (that is, the magnetization switching region). (Direction away from 8). The magnetization M1 of the spin-polarized current injection region 9 is directed in the + S direction (ie, the direction toward the magnetization switching region 8), and the magnetization M2 of the spin-polarized current injection region 10 is in the -T direction (ie, the magnetization switching region 8). In the direction of heading). In this case, as shown in FIG. 12C, the wiring 42 is connected to the other end of the magnetization switching region 8 through the via 41.

  In the MRAM having the configuration shown in FIG. 12B, when data “1” is written, a write current flows from the wiring 12 to the wiring 42, and a spin-polarized current is injected from the spin-polarized current injection region 9 into the magnetization switching region 8. Is done. As a result, the magnetization of the magnetization switching region 8 is directed in the + x direction, and data “1” is written. On the other hand, when data “0” is written, a write current is passed from the wiring 14 to the wiring 42, and a spin-polarized current is injected from the spin-polarized current injection region 10 to the magnetization switching region 8. Thereby, the magnetization of the magnetization switching region 8 is directed in the −x direction, and data “1” is written.

  The advantage of the configuration illustrated in FIG. 12B is that the magnetization of the spin-polarized current injection regions 9 and 10 can be directed in a desired direction by applying a magnetic field in the −y direction or the + y direction. . This is preferable in order to easily direct the magnetization of the spin-polarized current injection regions 9 and 10 in a desired direction in the manufacturing process.

  As shown in FIG. 12C, when both of the spin-polarized current injection regions 9 and 10 are connected to one end of the magnetization switching region 8, the composite ferromagnetic region 17 (or the composite nonmagnetic region 19 ) Need only be provided at one end of the magnetization switching region 8.

  The present invention is effective in reducing spin-polarized current in an MRAM (Magnetic Random Access Memory) in which data is written by reversing magnetization using a spin-polarized current.

Claims (11)

A magnetic recording layer comprising: a magnetization reversal region having a reversible magnetization; and a spin-polarized current injection region for injecting a spin-polarized current into the magnetization reversal region in an in-plane direction;
A magnetization fixed layer having a fixed magnetization;
A tunnel barrier layer provided between the magnetization switching region and the magnetization fixed layer;
Comprising
At least a part of the magnetization switching region is
(A) a first composite ferromagnetic material obtained by combining a non-oxidized metal ferromagnetic material and an oxide of a nonmagnetic material having an oxide generation energy lower than that of the metal ferromagnetic material;
(B) a second composite ferromagnetic material configured by combining the non-nitrided metal ferromagnetic material and the nonmagnetic material nitride having a lower nitride formation energy than the metal ferromagnetic material; and
(C) A third composite ferromagnetic material composed of a composite of a non-carbonized metal ferromagnetic material and a carbide of a nonmagnetic material having a lower carbide generation energy than the metal ferromagnetic material.
Formed with either
The magnetization switching region is
A composite ferromagnetic portion adjacent to the spin-polarized current injection region in the in-plane direction and formed of the composite ferromagnetic material;
A high MR ratio ferromagnetic part formed of a metal ferromagnetic material which is joined to the composite ferromagnetic part in a direction perpendicular to the in-plane direction and is provided between the composite ferromagnetic part and the tunnel barrier layer When,
Magnetic random access memory, characterized in that the Ru with a. A magnetic recording layer comprising: a magnetization reversal region having a reversible magnetization; and a spin-polarized current injection region for injecting a spin-polarized current into the magnetization reversal region in an in-plane direction;
A magnetization fixed layer having a fixed magnetization;
A tunnel barrier layer provided between the magnetization switching region and the magnetization fixed layer;
Comprising
At least a part of the magnetization switching region is
(A) a first composite ferromagnetic material obtained by combining a non-oxidized metal ferromagnetic material and an oxide of a nonmagnetic material having an oxide generation energy lower than that of the metal ferromagnetic material;
(B) a second composite ferromagnetic material configured by combining the non-nitrided metal ferromagnetic material and the nonmagnetic material nitride having a lower nitride formation energy than the metal ferromagnetic material; and
(C) A third composite ferromagnetic material composed of a composite of a non-carbonized metal ferromagnetic material and a carbide of a nonmagnetic material having a lower carbide generation energy than the metal ferromagnetic material.
Formed with either
The magnetization switching region is
A composite ferromagnetic portion formed of the composite ferromagnetic material;
A metal ferromagnetic part formed of a metal ferromagnetic material joined to the composite ferromagnetic part in the in-plane direction;
With
The composite ferromagnetic part, magnetic random access memory, characterized in that provided between the metallic ferromagnetic portion and the spin-polarized current injection region. The magnetic random access memory according to claim 2 , wherein at least a part of the tunnel barrier layer is directly joined to the metal ferromagnetic portion. The magnetization switching region further includes:
A high MR ratio ferromagnetic part formed of a metal ferromagnetic material joined between the metal ferromagnetic part and a direction perpendicular to the in-plane direction and provided between the metal ferromagnetic part and the tunnel barrier layer The magnetic random access memory according to claim 2 , further comprising: As the metal ferromagnetic material, one metal selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and gadolinium (Gd), or two or more elements selected from the group A ferromagnetic material made of an alloy of
Examples of the nonmagnetic material include magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), and titanium (Ti). , Vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium (Ce) A material of an element selected from the group consisting of yttrium (Y) and lanthanum (La), or a material consisting of two or more elements selected from the group is used. 5. The magnetic random access memory according to any one of items 1 to 4 . A magnetic recording layer comprising a magnetization reversal region having a reversible magnetization, a spin-polarized current injection region, and a composite material region provided between the magnetization reversal region and the spin-polarized current injection region;
A magnetization fixed layer having a fixed magnetization;
A tunnel barrier layer provided between the magnetization switching region and the magnetization fixed layer,
The spin-polarized current injection region is used to inject a spin-polarized current in an in-plane direction into the magnetization switching region through the composite material region,
The composite material region is
(A) a first composite material in which a non-oxidized first material and an oxide of a second material whose oxide generation energy is lower than that of the first material are combined;
(B) a second composite material in which a non-nitrided first material and a nitride of a second material whose oxide generation energy is lower than that of the first material are combined; and (c) a non-carbonized first material. A magnetic random access memory comprising: one material and a third composite material in which a carbide of a second material having an oxide generation energy lower than that of the first material is combined. The magnetic random access memory according to claim 6 , wherein the first material is a ferromagnetic material, and the second material is a nonmagnetic material. The first material is made of a metal selected from the group consisting of iron (Fe), cobalt (Co), nickel (Ni), and gadolinium (Gd), or an alloy of two or more elements selected from the group. Metal ferromagnetic material is used,
As the second material, magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), titanium (Ti) , Vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium (Ce) , yttrium (Y), and lanthanum (La) materials of an element selected from the group consisting of, or to claim 7, characterized in that the material of two or more elements selected from the group is used The magnetic random access memory described. The magnetic random access memory according to claim 6 , wherein both the first material and the second material are non-magnetic materials. As the first material, copper (Cu), silver (Ag), gold (Au), platinum (Pt), palladium (Pd), ruthenium (Ru), tantalum (Ta), aluminum (Al), osmium (Os) , Titanium (Ti), manganese (Mn), rhodium (Rh), iridium (Ir), silicon (Si), germanium (Ge), lead (Pb), gallium (Ga), bismuth (Bi), zinc (Zn) And an element material selected from the group consisting of antimony (Sb), or a material consisting of two or more elements selected from the group,
As the second material, magnesium (Mg), aluminum (Al), silicon (Si), germanium (Ge), lithium (Li), beryllium (Be), barium (Ba), calcium (Ca), titanium (Ti) , Vanadium (V), chromium (Cr), manganese (Mn), zirconium (Zr), hafnium (Hf), tantalum (Ta), niobium (Nb), chromium (Cr), molybdenum (Mo), cerium (Ce) , yttrium (Y), lanthanum (La) materials of an element selected from the group consisting of, or, according to claim 9, characterized in that the material of two or more elements selected from the group is used Magnetic random access memory. Forming first and second spin-polarized current injection regions above the substrate;
Forming a composite material film covering the first and second spin-polarized current injection regions;
Etching back the composite material film to form a composite material region on a side surface of the first and second spin-polarized current injection regions;
Forming a first ferromagnetic film covering the first and second spin-polarized current injection regions and the composite material region;
Forming an insulating film covering the first ferromagnetic film;
Forming a second ferromagnetic film covering the insulating film;
Forming a mask above the second ferromagnetic film so as to be positioned between the first and second spin-polarized current injection regions;
The first ferromagnetic film, the insulating film, and the second ferromagnetic film, a portion of the insulating film and the second ferromagnetic film not covered by the mask, and the first ferromagnetic film, Etching to leave a portion between the first and second spin-polarized current injection regions;
And
The composite film is
(A) a first composite material in which a non-oxidized first material and an oxide of a second material whose oxide generation energy is lower than that of the first material are combined;
(B) a second composite material in which a non-nitrided first material and a nitride of a second material whose oxide generation energy is lower than that of the first material are combined; and (c) a non-carbonized first material. 1. A magnetic random access memory comprising: a first material and a third composite material in which a carbide of a second material having an oxide generation energy lower than that of the first material is combined. Method.

Images