WO2010143248A1 - Élément en tunnel à effet de résistance magnétique et mémoire vive l'utilisant - Google Patents

Élément en tunnel à effet de résistance magnétique et mémoire vive l'utilisant Download PDF

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WO2010143248A1
WO2010143248A1 PCT/JP2009/060432 JP2009060432W WO2010143248A1 WO 2010143248 A1 WO2010143248 A1 WO 2010143248A1 JP 2009060432 W JP2009060432 W JP 2009060432W WO 2010143248 A1 WO2010143248 A1 WO 2010143248A1
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recording layer
region
layer
magnetization
tunnel magnetoresistive
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PCT/JP2009/060432
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English (en)
Japanese (ja)
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浩之 山本
宏昌 高橋
顕知 伊藤
純 早川
路彦 山ノ内
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株式会社日立製作所
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Priority to JP2011518149A priority Critical patent/JP5456035B2/ja
Priority to PCT/JP2009/060432 priority patent/WO2010143248A1/fr
Priority to TW099118380A priority patent/TWI430485B/zh
Publication of WO2010143248A1 publication Critical patent/WO2010143248A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/161—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11C—STATIC STORES
    • G11C11/00—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor
    • G11C11/02—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements
    • G11C11/16—Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor using magnetic elements using elements in which the storage effect is based on magnetic spin effect
    • G11C11/165—Auxiliary circuits
    • G11C11/1659—Cell access
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
    • H01F10/324—Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
    • H01F10/3254—Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer the spacer being semiconducting or insulating, e.g. for spin tunnel junction [STJ]
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
    • H01F10/324—Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
    • H01F10/3268—Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer the exchange coupling being asymmetric, e.g. by use of additional pinning, by using antiferromagnetic or ferromagnetic coupling interface, i.e. so-called spin-valve [SV] structure, e.g. NiFe/Cu/NiFe/FeMn
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
    • H01F10/324—Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
    • H01F10/3286—Spin-exchange coupled multilayers having at least one layer with perpendicular magnetic anisotropy
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F10/00—Thin magnetic films, e.g. of one-domain structure
    • H01F10/32—Spin-exchange-coupled multilayers, e.g. nanostructured superlattices
    • H01F10/324—Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer
    • H01F10/329—Spin-exchange coupled multilayers wherein the magnetisation of the free layer is switched by a spin-polarised current, e.g. spin torque effect
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N50/00—Galvanomagnetic devices
    • H10N50/10—Magnetoresistive devices
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10B—ELECTRONIC MEMORY DEVICES
    • H10B61/00—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices
    • H10B61/20—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors
    • H10B61/22—Magnetic memory devices, e.g. magnetoresistive RAM [MRAM] devices comprising components having three or more electrodes, e.g. transistors of the field-effect transistor [FET] type

Definitions

  • the present invention relates to a tunnel magnetoresistive effect element using a perpendicular magnetization material and a random access memory using the same.
  • MRAM Magnetic Random Access Memory
  • MRAM Magnetic Random Access Memory
  • MTJ Magnetic Tunneling Junction
  • TMR tunneling magnetoresistance
  • Patent Document 1 discloses an MTJ element using an in-plane magnetization material as a recording layer and utilizing spin-injection magnetization reversal and a memory in which the MTJ element is integrated: SPRAM (SPin-transfer magnetic Random Access Memory).
  • thermal stability of magnetic information in the MTJ element becomes a problem.
  • the thermal energy due to the environmental temperature is higher than the magnetic energy necessary for reversing the magnetization direction of the recording layer of the MTJ element, magnetization reversal occurs without applying an external magnetic field or current. Since the magnetic energy of the MTJ element decreases as the size decreases, this thermal stability decreases as the element becomes finer. In order to maintain thermal stability even in a fine region and realize a highly reliable operation, it is effective to increase the magnetocrystalline anisotropy of the recording layer material of the MTJ element.
  • Patent Document 2 an MTJ element using a perpendicular magnetization material having higher magnetocrystalline anisotropy than an in-plane magnetization material has been disclosed (Patent Document 2). Further, in the MTJ element to which the perpendicular magnetization material is applied, the influence of the demagnetizing field applied in the recording layer is different from the in-plane magnetization MTJ element and works in the direction of reducing the current density required for the magnetization reversal (write current density). Therefore, compared with the in-plane magnetization MTJ element, there is an advantage that the write current density can be reduced and the power consumption can be suppressed.
  • the perpendicular magnetization thin film used for the recording layer has a single domain structure that does not include a domain wall, and the magnetization reversal becomes a simultaneous magnetization reversal mechanism, so that the write current density increases.
  • Patent Document 3 a region having a smaller coercive force than the central portion is provided in the outer peripheral portion of the recording layer, and first, the magnetization of the outer peripheral portion is reversed when an external magnetic field is applied, and the magnetization of the central portion is reversed by the leakage magnetic field. Shows how to assist. JP 2002-305337 A JP 2003-142364 A JP 2002-299727 A
  • an object of the present invention is to provide a perpendicular magnetization MTJ element that can reduce the write current as compared with the prior art. Further, it is an object of the present invention to provide a perpendicular magnetization MTJ element that can reduce a write current even in a very fine region in which a recording layer has a single magnetic domain structure.
  • the magnetization reversal efficiency is better when the magnetization of the central portion is reversed before the outer peripheral portion of the recording layer because the above-described propagation of the domain wall easily proceeds. Furthermore, as in Patent Document 3, it is necessary to lower the resistance of the outer peripheral portion from the central portion in order to reverse the magnetization of the outer peripheral portion first, but normally the outer peripheral portion is exposed to an ion beam during the MTJ element shape processing. High resistance. Therefore, it is difficult to reverse the magnetization of the outer peripheral portion before the central portion by current injection.
  • a structure in which a part of a magnetic thin film used as a recording layer of an MTJ element is made thinner than its surroundings is applied.
  • a structure in which the magnetic moment per unit area of a partial region of the magnetic thin film used as the recording layer is reduced from the surroundings is applied.
  • the tunnel magnetoresistive element of the present invention includes a recording layer made of a perpendicular magnetization film, a fixed layer made of a perpendicular magnetization film, a nonmagnetic layer disposed between the recording layer and the fixed layer, A pair of electrode layers is formed in contact with each of the recording layer and the fixed layer, and flows a current for reversing the magnetization direction of the recording layer in the element film thickness direction.
  • the recording layer includes at least one of a first region and a second region, and the magnetic moment per unit area in the first region is lower than the magnetic moment per unit area in the second region, and the outer periphery of the recording layer The ratio of the second area to the portion is larger than the ratio of the first area.
  • the write current density in the perpendicular magnetization MTJ element can be further reduced as compared with the prior art. Furthermore, even if the magnetic thin film of the recording layer is a very fine element having a single magnetic domain structure, an increase in write current density can be suppressed.
  • FIG. 5 is a diagram showing a manufacturing process of the MTJ element of Example 1.
  • FIG. 3 is a diagram schematically showing a magnetization reversal mechanism of the MTJ element of Example 1. It is a schematic diagram of the MTJ element of Example 2, (A) is a cross-sectional schematic diagram, (B) is a top schematic diagram. It is a schematic diagram of the MTJ element of Example 3, (A) is a cross-sectional schematic diagram, (B) is a top schematic diagram.
  • FIG. 10 is a view showing a manufacturing process of the MTJ element of Example 5.
  • 6 is a schematic cross-sectional view of an MTJ element according to Example 6.
  • FIG. It is a cross-sectional schematic diagram which shows the structural example of a magnetic memory cell. It is a schematic diagram which shows the structural example of a random access memory.
  • the magnetization of the recording layer is reversed by utilizing the mechanism of spin injection magnetization reversal. That is, a current is passed through the element, and the spin of the spin-polarized current gives a torque to the magnetic moment of the magnetic recording layer, thereby reversing the magnetization of the recording layer.
  • FIG. 1 is a schematic diagram of an MTJ element in Example 1.
  • 1A is a schematic cross-sectional view
  • FIG. 1B is a schematic top view.
  • the element is configured by laminating a lower electrode layer 21, a ferromagnetic fixed layer 11, a nonmagnetic layer 23, a ferromagnetic recording layer 10, and an upper electrode layer 22 on a substrate 20.
  • the element is circular with a diameter W when viewed from above.
  • the magnetizations of the recording layer 10 and the fixed layer 11 are perpendicular to the film surface.
  • the material and film thickness of the recording layer 10 and the fixed layer 11 are set so that the magnetization of the recording layer 10 is reversed before the magnetization of the fixed layer 11 when a spin-polarized current is passed.
  • the upper electrode layer 22 and the lower electrode layer 21 are connected to wirings for supplying current to the element.
  • Example 1 using the L1 0 type Co 50 Pt 50 ordered alloy in the material of the fixed layer 11 and the recording layer 10. Further, a laminated film made of Ta, Ru, Pt was used for the lower electrode layer 21, and a laminated film made of Ta, Ru was used for the upper electrode layer 22. Further, magnesium oxide (MgO) was used for the nonmagnetic layer 23.
  • the recording layer 10 has a thickness t 0 of 3 nm
  • the fixed layer 11 has a thickness t 1 of 10 nm
  • the nonmagnetic layer 23 has a thickness of 1 nm.
  • the diameter W of the element was 30 nm
  • the diameter D of the concave portion provided in the center of the recording layer 10 was 10 nm.
  • FIG. 2 shows a manufacturing process of the element.
  • description will be given in the order of steps shown in FIGS. 2 (A) to 2 (H).
  • a laminated film 25 in which a lower electrode layer 21, a fixed layer 11, a nonmagnetic layer 23, a recording layer 10, and an upper electrode layer 22 were laminated in this order was formed on a substrate 20 (FIG. 2A).
  • a thin film was formed by sputtering, and all layers were formed in-situ.
  • the laminated film 25 was processed into a pillar shape by using electron beam (EB) lithography and ion beam etching (FIG. 2B).
  • EB electron beam
  • Al 2 O 3 was deposited as an interlayer insulating layer 52 with the resist pattern 51 remaining on the pillar surface (FIG. 2C). Thereafter, the resist on the pillar surface was removed by lift-off to expose the pillar surface (FIG. 2D).
  • a resist was applied from above the exposed pillar, and a resist pattern having an opening at the upper center of the pillar was formed by EB lithography (FIG. 2E).
  • the upper electrode layer 21 and part of the recording layer 10 were removed by etching with an ion beam (FIG. 2F).
  • the depth h for etching the central portion of the recording layer 10 was 1 nm.
  • Ru and Ta to be the additional upper electrode layer 26 were deposited in-situ by sputtering to cover the upper part of the pillar (FIG. 2G).
  • the device was annealed at a temperature of 300 ° C.
  • a nanoimprint technique may be used for forming the resist pattern 51 as a technique other than the EB lithography.
  • the magnetization of the fixed layer 11 is fixed in the upper direction of the element.
  • the magnetization of the recording layer 10 has an antiparallel arrangement in the opposite direction to the magnetization of the fixed layer 11
  • spin-polarized electrons are transferred from the fixed layer 11.
  • the magnetization of the recording layer 10 is reversed by flowing into the recording layer 10 and reversing the spin injection magnetization. That is, the magnetization of the fixed layer 11 and the magnetization of the recording layer 10 are arranged in parallel, and the resistance of the MTJ element is switched from the high resistance state to the low resistance state.
  • the magnetization of the recording layer 10 has a parallel arrangement in the same direction as the magnetization of the fixed layer 11, when a current is passed from the lower part to the upper part of the MTJ element, spin-polarized electrons are generated. And flows to the fixed layer 11. At that time, only electrons having a spin in the same direction as the spin of the fixed layer 11 flow into the fixed layer 11, and the electrons having a spin in the reverse direction are reflected on the surface of the insulator 23. The reflected electrons act on the magnetization of the recording layer 10, and the magnetization of the recording layer 10 is reversed by spin injection magnetization reversal. That is, the magnetization of the fixed layer 11 and the magnetization of the recording layer 10 become an antiparallel arrangement, and the resistance of the MTJ element is switched from the low resistance state to the high resistance state.
  • Example 1 the thickness of the central portion of the recording layer 10 is reduced. Therefore, the magnetization reversal of the recording layer 10 proceeds as follows. First, consider a state in which the magnetization of the recording layer faces the upper side of the film surface (FIG. 3A). When spin-polarized electrons are caused to flow from the upper side to the lower side of the element, first, magnetization reversal occurs in the central region where the film thickness is thin (FIG. 3B). That is, a magnetization reversal nucleus is formed. At that time, a domain wall 35 is formed around the central portion where the magnetization is reversed in the recording layer 10. The formed domain wall 35 propagates toward the outer periphery of the element (FIG.
  • the magnetization of the entire recording layer is reversed (FIG. 3D).
  • the film thickness of the recording layer 10 is uniform, and in the case of the same size as in the first embodiment, a single magnetic domain structure is formed. Therefore, the magnetization rotates all over the entire area of the recording layer 10.
  • a region where the magnetization is easily reversed is provided in the central portion, and if the magnetization is reversed, the entire magnetization is reversed by propagation of the domain wall.
  • the current density (J C0 ) at which magnetization reversal starts can be reduced as compared with the conventional structure in which no concave region is provided in the recording layer, and power consumption can be reduced.
  • the write current it was possible to reduce the write current to about 50% as compared with a perpendicular magnetization MTJ element having a conventional structure in which no concave region was provided in the recording layer.
  • the width ⁇ of the domain wall depends on the crystal anisotropy energy Ku of the magnetic material and is proportional to 1 / ⁇ Ku. In the case of a CoPt ordered alloy having a high crystal anisotropy energy Ku of about 10 7 erg / cm 2 , the domain wall width ⁇ is about 5 to 10 nm.
  • the diameter D (10 nm) of the concave region is equal to or larger than the domain wall width ⁇ .
  • the diameter D of the concave region of the recording layer is 10 nm. However, in order to obtain the same effect as in this example, it is preferably 5 nm or more at the minimum.
  • the diameter W of the recording layer is W> D + 2 ⁇ using the diameter D of the concave region and the width ⁇ of the domain wall of the ferromagnetic material. It is desirable.
  • the diameter W of the recording layer is 30 nm
  • the diameter D of the concave region is 10 nm
  • the domain wall width ⁇ is about 5 to 10 nm, which satisfies this relationship.
  • the write current density of the perpendicular magnetization MTJ element is represented by J C0 ⁇ (M S H k ⁇ 4 ⁇ M S 2 ) ⁇ t (M S : saturation magnetization of the recording layer material, H k : different recording layer material) Isotropic magnetic field, t: film thickness of recording layer). That is, the current density required for magnetization reversal is proportional to the thickness of the recording layer.
  • the film of the concave area in the recording layer 10 is used. It is desirable that the thickness be at least about 80% of the circumference.
  • Example 1 as a perpendicular magnetization material of the recording layer 10 and the fixed layer 11, L1 0 type is applied the Co 50 Pt 50 ordered alloy, the same as also in Example 1 by applying other perpendicularly magnetized material Needless to say, an effect can be obtained.
  • Specific materials include, for example, L1 1 type CoPt ordered alloy, m-D0 19 type Co 75 Pt 35 ordered alloy, L1 0 type ordered alloy such as Fe 50 Pt 50 , or CoCrPt—SiO 2 , FePt— A granular structure material in which a granular magnetic material such as SiO 2 is dispersed in a non-magnetic matrix, or an alloy containing one or more of Fe, Co, Ni, and Ru, Pt, Rh, Pd, A laminated film in which nonmagnetic metals such as Cr are alternately laminated, or an amorphous alloy containing a transition metal in a rare earth metal such as Gd, Dy, or Tb such as TbFeCo or GdFeCo may be used.
  • Example 1 a circular concave area is formed in the circular recording layer.
  • the shape of the concave area may be, for example, a square shape other than the circular shape.
  • an extremely fine element having an area where the recording layer 10 has a single magnetic domain structure is proposed.
  • the present invention can be applied to an element having a larger dimension.
  • an MTJ element having a diameter of 100 nm when viewed from the top even in a conventional structure in which no concave region is provided in the recording layer, a magnetic domain is formed in the recording layer when the magnetization is reversed by current injection, and the recording layer is propagated by the propagation of the domain wall. The entire magnetization is reversed.
  • an MTJ element with a thin film thickness at the central portion of the recording layer to which the present invention is applied can induce the generation of magnetization reversal nuclei, and the write current density is lower than that of a conventional element that does not provide a concave region in the recording layer. Needless to say, it can be further reduced.
  • Example 2 proposes a rectangular perpendicular magnetization MTJ element.
  • FIG. 4 shows a schematic cross-sectional view and a top view of the MTJ element of Example 2.
  • the basic structure of the element, the structure and material of the laminated film, and the film thickness of each layer are the same as in Example 1.
  • the element of Example 2 has a square shape when viewed from above, and as shown in FIG. 4, a region having a smaller film thickness than the surroundings is provided in the center of the recording layer 10 (film thickness t 0 : 3 nm).
  • One side A of the element was 30 nm
  • one side B of the concave portion provided in the center of the recording layer 10 was 10 nm
  • the groove depth h of the concave portion was 1 nm.
  • the upper electrode layer 22 and the lower electrode layer 21 are connected to wirings for supplying current to the element.
  • the rewriting operation and magnetization reversal mechanism of the MTJ element of Example 2 are the same as those of Example 1.
  • magnetization reversal occurs from a thin central portion, and magnetization of the entire recording layer 10 is reversed by domain wall movement.
  • the write current density can be reduced as compared with a perpendicular magnetization MTJ element having a conventional structure in which no concave region is provided in the recording layer.
  • one side B of the concave region is equal to or larger than the domain wall width ⁇ .
  • one side B of the concave region of the recording layer is 10 nm.
  • the minimum is 5 nm or more.
  • one side A of the recording layer is A> B + 2 ⁇ using one side B of the concave region and the domain wall width ⁇ of the ferromagnetic material. It is desirable.
  • one side A of the recording layer is 30 nm
  • one side B of the concave region is 10 nm
  • the domain wall width ⁇ is about 5 to 10 nm, which satisfies this relationship.
  • the write current density of the perpendicular magnetization MTJ element is represented by J C0 ⁇ (M S H k ⁇ 4 ⁇ M S 2 ) ⁇ t (M S : saturation magnetization of the recording layer material, H k : different recording layer material) Isotropic magnetic field, t: film thickness of recording layer). That is, the current density required for magnetization reversal is proportional to the thickness of the recording layer.
  • the film of the concave area in the recording layer 10 is used. It is desirable that the thickness be at least about 80% of the circumference.
  • Example 2 as a perpendicular magnetization material of the recording layer 10 and the fixed layer 11, L1 0 type is applied the Co 50 Pt 50 ordered alloy, the same as also in Example 2 by applying the other perpendicular magnetization material Needless to say, an effect can be obtained.
  • Specific materials include, for example, L1 1 type CoPt ordered alloy, m-D0 19 type Co 75 Pt 35 ordered alloy, L1 0 type ordered alloy such as Fe 50 Pt 50 , or CoCrPt—SiO 2 , FePt— A granular structure material in which a granular magnetic material such as SiO 2 is dispersed in a non-magnetic matrix, or an alloy containing one or more of Fe, Co, Ni, and Ru, Pt, Rh, Pd, A laminated film in which nonmagnetic metals such as Cr are alternately laminated, or an amorphous alloy containing a transition metal in a rare earth metal such as Gd, Dy, or Tb such as TbFeCo or GdFeCo may be used.
  • the quadrangular concave region is formed in the quadrangular recording layer.
  • the concave region may have a shape other than the quadrangle, for example, a circle.
  • Example 3 proposes a quadrangular perpendicular magnetization MTJ element as in Example 2.
  • FIG. 5 shows a schematic cross-sectional view and a top view of the MTJ element of Example 3.
  • the basic structure of the element, the configuration and material of the laminated film, and the film thickness of each layer are the same as in the first and second embodiments.
  • the element of Example 3 has a quadrangular shape when viewed from above.
  • a region having a thinner film thickness than the surrounding is provided in the center of the recording layer 10.
  • the concave portion region is connected from one side of the element outer periphery to the opposite side.
  • One side A of the element was 30 nm, and the width B of the concave portion provided in the center of the recording layer 10 was 10 nm.
  • the upper electrode layer 22 and the lower electrode layer 21 are connected to wirings for supplying current to the element.
  • Example 3 The MTJ element rewriting operation and the magnetization reversal mechanism of Example 3 are the same as those of Example 1.
  • magnetization reversal occurs from a thin central portion, and magnetization of the entire recording layer 10 is reversed by domain wall movement.
  • the write current density can be reduced as compared with a conventional perpendicular magnetization MTJ element in which no concave region is provided in the recording layer.
  • the width B of the concave region is equal to or larger than the width ⁇ of the domain wall.
  • the width B of the concave region of the recording layer was 10 nm.
  • the width be at least 5 nm.
  • one side A of the recording layer is A> B + 2 ⁇ using one side B of the concave region and the domain wall width ⁇ of the ferromagnetic material. It is desirable.
  • one side A of the recording layer is 30 nm
  • one side B of the concave region is 10 nm
  • the domain wall width ⁇ is about 5 to 10 nm, which satisfies this relationship.
  • the write current density of the perpendicular magnetization MTJ element is represented by J C0 ⁇ (M S H k ⁇ 4 ⁇ M S 2 ) ⁇ t (M S : saturation magnetization of the recording layer material, H k : different recording layer material) Isotropic magnetic field, t: film thickness of recording layer). That is, the current density required for magnetization reversal is proportional to the thickness of the recording layer.
  • the film of the concave area in the recording layer 10 is used. It is desirable that the thickness be at least about 80% of the circumference.
  • Example 3 as a perpendicular magnetization material of the recording layer 10 and the fixed layer 11, L1 0 type is applied the Co 50 Pt 50 ordered alloy, the same as also in Example 3 by applying other perpendicularly magnetized material Needless to say, an effect can be obtained.
  • Specific materials include, for example, L1 1 type CoPt ordered alloy, m-D0 19 type Co 75 Pt 35 ordered alloy, L1 0 type ordered alloy such as Fe 50 Pt 50 , or CoCrPt—SiO 2 , FePt— A granular structure material in which a granular magnetic material such as SiO 2 is dispersed in a non-magnetic matrix, or an alloy containing one or more of Fe, Co, Ni, and Ru, Pt, Rh, Pd, A laminated film in which nonmagnetic metals such as Cr are alternately laminated, or an amorphous alloy containing a transition metal in a rare earth metal such as Gd, Dy, or Tb such as TbFeCo or GdFeCo may be used.
  • Example 4 proposes a perpendicular magnetization MTJ element having a plurality of concave portions.
  • FIG. 6 shows a schematic cross-sectional view and a top view of the MTJ element of Example 4.
  • the basic structure of the element, the configuration and material of the laminated film, and the film thickness of each layer are the same as in Example 3.
  • a plurality of concave portions are formed.
  • the side A of the element was 100 nm, and the width B of the concave region provided in the recording layer 10 was 10 nm.
  • the upper electrode layer 22 and the lower electrode layer 21 are connected to wirings for supplying current to the element.
  • the rewriting operation and magnetization reversal mechanism of the MTJ element of Example 4 are basically the same as those of Example 1. Magnetization reversal occurs from the two thin portions provided in the recording layer 10, and the magnetization of the entire recording layer 10 is reversed by the domain wall movement. As a result, the write current density can be reduced as compared with the conventional perpendicular magnetization MTJ element in which no concave region is provided in the recording layer.
  • the width B of the concave region is equal to or larger than the width ⁇ of the domain wall.
  • the width B of the concave region of the recording layer is 10 nm.
  • the width be at least 5 nm.
  • the write current density of the perpendicular magnetization MTJ element is represented by J C0 ⁇ (M S H k ⁇ 4 ⁇ M S 2 ) ⁇ t (M S : saturation magnetization of the recording layer material, H k : different recording layer material) Isotropic magnetic field, t: film thickness of recording layer). That is, the current density required for magnetization reversal is proportional to the thickness of the recording layer.
  • the film of the concave area in the recording layer 10 is used. It is desirable that the thickness be at least about 80% of the circumference.
  • Example 4 as a perpendicular magnetization material of the recording layer 10 and the fixed layer 11, L1 0 type is applied the Co 50 Pt 50 ordered alloy, the same as also in Example 4 by applying the other perpendicular magnetization material Needless to say, an effect can be obtained.
  • Specific materials include, for example, L1 1 type CoPt ordered alloy, m-D0 19 type Co 75 Pt 35 ordered alloy, L1 0 type ordered alloy such as Fe 50 Pt 50 , or CoCrPt—SiO 2 , FePt— A granular structure material in which a granular magnetic material such as SiO 2 is dispersed in a non-magnetic matrix, or an alloy containing one or more of Fe, Co, Ni, and Ru, Pt, Rh, Pd, A laminated film in which nonmagnetic metals such as Cr are alternately laminated, or an amorphous alloy containing a transition metal in a rare earth metal such as Gd, Dy, or Tb such as TbFeCo or GdFeCo may be used.
  • Example 5 proposes an MTJ element that realizes nucleation of magnetization reversal in a recording layer by controlling physical properties, not the shape of the recording layer.
  • FIG. 7 is a schematic cross-sectional view of the MTJ element in Example 5.
  • the basic structure of the element is the same as that of the first embodiment.
  • the recording layer 10 and the fixed layer 11 were made of a Co 50 Pt 50 alloy, which is a perpendicularly magnetized ferromagnetic material, and MgO was used for the nonmagnetic layer 23.
  • the upper electrode layer 22 includes a first cap layer 41 and a second cap layer 42.
  • the first cap layer 41 is disposed substantially at the center of the recording layer 10, and the second cap layer 42 is disposed around the first cap layer 41.
  • the first cap layer 41 was Ti, and Pt was used for the second cap layer 42.
  • a reaction region 43 is formed in the recording layer 10 by reaction with the first cap layer 41.
  • the recording layer 10 has a thickness t 0 of 3 nm
  • the fixed layer 11 has a thickness t 1 of 10 nm
  • the nonmagnetic layer 23 has a thickness of 1 nm.
  • the diameter W of the element was 30 nm
  • the diameter D of the first cap layer 41 was 10 nm.
  • the upper electrode layer 22 and the lower electrode layer 21 are connected to wirings for supplying current to the element.
  • FIG. 8 shows a manufacturing process of the element.
  • description will be made in accordance with the order of steps shown in FIGS. 8A to 8I.
  • a laminated film 25 in which the lower electrode layer 21, the fixed layer 11, the nonmagnetic layer 23, the recording layer 10, and the first cap layer 41 were laminated in this order was formed on the substrate 20 (FIG. 8A).
  • a thin film was formed by sputtering, and all layers were formed in-situ.
  • the laminated film 25 was processed into a pillar shape by using electron beam (EB) lithography and ion beam etching (FIG. 8B).
  • EB electron beam
  • the second cap layer 42 was processed into the shape of the upper electrode layer by using EB lithography and ion beam etching (FIG. 8I). Finally, the device was annealed at a temperature of 400 ° C. to form a reaction region 43 to complete the MTJ device (FIG. 8J).
  • the EB lithography is used for forming the resist pattern.
  • a nanoimprint technique may be used as another pattern technique.
  • the recording layer 10 is substantially equivalent to the thin film thickness in the central portion as in the first embodiment. Therefore, when a current is passed through the element to reverse the magnetization, the same mechanism as that of the element of Example 1 works. That is, first, the magnetization of the central portion is reversed, the domain wall formed around the center is propagated toward the outer periphery, and the magnetization of the entire recording layer 10 is reversed. With this magnetization reversal mechanism, the current density required for rewriting magnetic information can be reduced as compared with the conventional MTJ element in which the recording layer is not provided with the concave region, as in the first embodiment.
  • the diameter D of the first cap layer 41 is desirably equal to or greater than the domain wall width ⁇ .
  • the diameter D of the first cap layer 41 is 10 nm.
  • it is desirable that the diameter is at least 5 nm.
  • the write current density of the perpendicular magnetization MTJ element is represented by J C0 ⁇ (M S H k ⁇ 4 ⁇ M S 2 ) ⁇ t (M S : saturation magnetization of the recording layer material, H k : different recording layer material) Isotropic magnetic field, t: film thickness of recording layer). That is, the current density required for magnetization reversal is proportional to the thickness of the recording layer.
  • the reaction is performed in the central portion of the recording layer 10. It is desirable that the film thickness not including the region 43 (t 0 -h) be at least about 80% or less of the surrounding film thickness (t 0 ).
  • Example 5 as a perpendicular magnetization material of the recording layer 10 and the fixed layer 11, L1 0 type is applied the Co 50 Pt 50 ordered alloy, the same as also Example 5 by applying other perpendicularly magnetized material Needless to say, an effect can be obtained.
  • Specific materials include, for example, L1 1 type CoPt ordered alloy, m-D0 19 type Co 75 Pt 35 ordered alloy, L1 0 type ordered alloy such as Fe 50 Pt 50 , or CoCrPt—SiO 2 , FePt— A granular structure material in which a granular magnetic material such as SiO 2 is dispersed in a non-magnetic matrix, or an alloy containing one or more of Fe, Co, Ni, and Ru, Pt, Rh, Pd, A laminated film in which nonmagnetic metals such as Cr are alternately laminated, or an amorphous alloy containing a transition metal in a rare earth metal such as Gd, Dy, or Tb such as TbFeCo or GdFeCo may be used.
  • Example 5 Ti and Pt are used as a combination of the materials of the first cap layer 41 and the second cap layer 42, but other materials may be used.
  • Ta or Ru may be used as the second cap layer 42.
  • the rectangular reaction region 43 is formed in the rectangular recording layer.
  • the reaction region 43 may have a shape other than the square, for example, a circle.
  • Example 6 proposes an MTJ element that realizes nucleation of magnetization reversal in a recording layer by controlling the crystallinity rather than the shape of the recording layer.
  • FIG. 9 is a schematic cross-sectional view of the MTJ element in Example 6.
  • the basic structure of the element is the same as that of the first embodiment.
  • the recording layer 10 and the fixed layer 11 were made of a Co 50 Pt 50 alloy, which is a perpendicularly magnetized ferromagnetic material, and MgO was used for the nonmagnetic layer 23.
  • a modified region 44 is included in the recording layer 10 as shown in FIG.
  • the modified region 44 is a region made amorphous.
  • the film thickness t 0 of the recording layer 10 was 3 nm
  • the film thickness t 1 of the fixed layer 11 was 10 nm
  • the film thickness of the nonmagnetic layer 23 was 1 nm.
  • the diameter W of the element was 30 nm
  • the diameter D of the modified region 44 was 10 nm.
  • the upper electrode layer 22 and the lower electrode layer 21 are connected to wirings for supplying current to the element.
  • Example 6 A device fabrication method of Example 6 will be described.
  • the manufacturing method is basically the same as that of the device of Example 1 shown in FIG. However, this is different after the pillars of the laminated film 25 are formed and the resist pattern 51 on the pillar surface is removed by lift-off.
  • a focused ion beam is irradiated from the upper center of the recording layer 10 to modify the crystal structure of the central portion of the recording layer 10.
  • the upper electrode layer 22 was formed and processed by EB lithography and ion beam etching to complete the MTJ element. Finally, heat treatment was performed at a temperature of 300 ° C.
  • the modified region 44 in the recording layer 10 has a different crystal structure from the other regions, and the crystal structure is amorphous. Since the amorphous region does not generate perpendicular magnetization, it is substantially equivalent to a reduction in the thickness of the central portion of the recording layer 10 as in the first embodiment. Therefore, when a current is passed through the element to reverse the magnetization, the same mechanism as that of the element of Example 1 works. That is, first, the magnetization of the central portion is reversed, the domain wall formed around the center is propagated toward the outer periphery, and the magnetization of the entire recording layer 10 is reversed. With this magnetization reversal mechanism, the current density required for rewriting magnetic information can be reduced as compared with the conventional MTJ element in which the recording layer is not provided with the concave region, as in the first embodiment.
  • the diameter D of the modified region 44 is desirably equal to or greater than the domain wall width ⁇ .
  • the diameter D of the modified region 44 is 10 nm.
  • the write current density of the perpendicular magnetization MTJ element is represented by J C0 ⁇ (M S H k ⁇ 4 ⁇ M S 2 ) ⁇ t (M S : saturation magnetization of the recording layer material, H k : different recording layer material) Isotropic magnetic field, t: film thickness of recording layer). That is, the current density required for magnetization reversal is proportional to the thickness of the recording layer.
  • the recording layer 10 is modified in the central portion. It is desirable that the film thickness (t 0 -h) not including the quality region 44 be at least about 80% or less of the surrounding film thickness (t 0 ).
  • Example 6 a perpendicular magnetization material of the recording layer 10 and the fixed layer 11, L1 0 type is applied the Co 50 Pt 50 ordered alloy, the same as also Example 6 by applying the other perpendicular magnetization material Needless to say, an effect can be obtained.
  • Specific materials include, for example, L1 1 type CoPt ordered alloy, m-D0 19 type Co 75 Pt 35 ordered alloy, L1 0 type ordered alloy such as Fe 50 Pt 50 , or CoCrPt—SiO 2 , FePt— A granular structure material in which a granular magnetic material such as SiO 2 is dispersed in a non-magnetic matrix, or an alloy containing one or more of Fe, Co, Ni, and Ru, Pt, Rh, Pd, A laminated film in which nonmagnetic metals such as Cr are alternately laminated, or an amorphous alloy containing a transition metal in a rare earth metal such as Gd, Dy, or Tb such as TbFeCo or GdFeCo may be used.
  • the quadrangular modified region 44 is formed in the quadrangular recording layer, but the modified region 44 may have a shape other than the quadrangle, such as a circle.
  • FIG. 10 is a schematic cross-sectional view showing a configuration example of a magnetic memory cell according to the present invention.
  • This magnetic memory cell 100 is equipped with the MTJ element 110 shown in the first to sixth embodiments.
  • the C-MOS 111 is composed of two n-type semiconductors 112 and 113 and one p-type semiconductor 114.
  • An electrode 121 serving as a drain is electrically connected to the n-type semiconductor 112, and is connected to the ground via the electrode 141 and the electrode 147.
  • An electrode 122 serving as a source is electrically connected to the n-type semiconductor 113.
  • 123 is a gate electrode, and ON / OFF of the current between the source electrode 122 and the drain electrode 121 is controlled by ON / OFF of the gate electrode 123.
  • An electrode 145, an electrode 144, an electrode 143, an electrode 142, and an electrode 146 are stacked on the source electrode 122, and the lower electrode 11 of the MTJ element 110 is connected via the electrode 146.
  • the bit line 222 is connected to the upper electrode 22 of the MTJ element 110.
  • magnetic information is recorded by rotating the magnetization direction of the recording layer of the MTJ element 110 by the current flowing through the MTJ element 110, that is, the spin transfer torque.
  • the spin transfer torque is not a spatial external magnetic field, but is a principle in which spins of a spin-polarized current flowing in the MTJ element mainly give torque to the magnetic moment of the ferromagnetic free layer of the MTJ element. Accordingly, the MTJ element is provided with means for supplying current from the outside, and spin transfer torque magnetization reversal is realized by flowing current using the means.
  • the direction of magnetization of the recording layer 110 is controlled by passing a current between the bit line 222 and the electrode 146.
  • FIG. 11 is a diagram showing a configuration example of a magnetic random access memory in which the magnetic memory cell 100 is arranged.
  • a word line 223 and a bit line 222 connected to the gate electrode 123 are electrically connected to the memory cell 100.
  • the magnetic memory cell 100 including the MTJ element described in the first to sixth embodiments the magnetic memory uses the in-plane magnetization MTJ element or the conventional magnetic magnetization MTJ element that does not provide the concave region in the recording layer. Operation with lower power consumption than memory is possible, and a gigabit-class high-density magnetic memory can be realized.
  • a write enable signal is sent to the write driver connected to the bit line 222 to which a current is to be supplied to boost the voltage, and a predetermined current is supplied to the bit line 222.
  • a predetermined current is supplied to the bit line 222.
  • either the write driver 230 or the write driver 231 is dropped to the ground, and the current direction is controlled by adjusting the potential difference.
  • a write enable signal is sent to the write driver 232 connected to the word line 223 to boost the write driver 232 and turn on the transistor connected to the MTJ element to be written. As a result, a current flows through the MTJ element, and spin torque magnetization reversal is performed.
  • the signal to the write driver 232 is disconnected and the transistor is turned off.

Abstract

L'invention concerne un élément à effet de résistance magnétique qui utilise un matériau aimanté verticalement et présente une densité de courant d'écriture réduite. Une zone caractérisée par une épaisseur de film inférieure à celle de la zone environnante est formée dans la partie centrale d'une couche (10) d'enregistrement. En variante, une zone faisant fonction de corps ferromagnétique et présentant une épaisseur effective de film inférieure à celle de la zone environnante est formée dans la partie centrale de la couche d'enregistrement.
PCT/JP2009/060432 2009-06-08 2009-06-08 Élément en tunnel à effet de résistance magnétique et mémoire vive l'utilisant WO2010143248A1 (fr)

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JP2011518149A JP5456035B2 (ja) 2009-06-08 2009-06-08 トンネル磁気抵抗効果素子及びそれを用いたランダムアクセスメモリ
PCT/JP2009/060432 WO2010143248A1 (fr) 2009-06-08 2009-06-08 Élément en tunnel à effet de résistance magnétique et mémoire vive l'utilisant
TW099118380A TWI430485B (zh) 2009-06-08 2010-06-07 Tunneling magnetoresistive element using the same, and a RAM (Random Access Memory)

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JP2019087697A (ja) * 2017-11-09 2019-06-06 株式会社日立製作所 熱電変換装置および熱輸送システム
WO2021186968A1 (fr) * 2020-03-17 2021-09-23 ソニーセミコンダクタソリューションズ株式会社 Dispositif à semi-conducteurs et son procédé de fabrication

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JP2009081314A (ja) * 2007-09-26 2009-04-16 Toshiba Corp 磁気抵抗素子及び磁気メモリ
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JP2008186861A (ja) * 2007-01-26 2008-08-14 Toshiba Corp 磁気抵抗素子および磁気メモリ
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JP2014049766A (ja) * 2012-08-30 2014-03-17 Samsung Electronics Co Ltd 磁気メモリ素子、磁性素子及び磁性素子の製造方法
JP2019087697A (ja) * 2017-11-09 2019-06-06 株式会社日立製作所 熱電変換装置および熱輸送システム
WO2021186968A1 (fr) * 2020-03-17 2021-09-23 ソニーセミコンダクタソリューションズ株式会社 Dispositif à semi-conducteurs et son procédé de fabrication

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