KR101661430B1 - Magnetic tunnel junction structure with perpendicular magnetic anisotropy and Magnetic element including the same - Google Patents

Magnetic tunnel junction structure with perpendicular magnetic anisotropy and Magnetic element including the same Download PDF

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KR101661430B1
KR101661430B1 KR1020150088802A KR20150088802A KR101661430B1 KR 101661430 B1 KR101661430 B1 KR 101661430B1 KR 1020150088802 A KR1020150088802 A KR 1020150088802A KR 20150088802 A KR20150088802 A KR 20150088802A KR 101661430 B1 KR101661430 B1 KR 101661430B1
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South Korea
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layer
ferromagnetic
selective diffusion
diffusion preventing
magnetic anisotropy
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KR1020150088802A
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Korean (ko)
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홍진표
이자빈
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한양대학교 산학협력단
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Abstract

Provided are a magnetic tunnel junction (MTJ) structure with perpendicular magnetic anisotropy and a magnetic element including the same. The MTJ structure with perpendicular magnetic anisotropy is a structure where a fixing layer, a tunneling barrier layer and a free layer are sequentially stacked on a substrate, wherein the free layer is a duplicate ferromagnetic layer structure which includes a structure of a first ferromagnetic layer/a first selective diffusion protecting layer/an intermediate layer/a second selective diffusion protecting layer/a second ferromagnetic layer. Thus, in the free layer of the duplicate ferromagnetic layer structure where the first and second selective diffusion protecting layers prevent a metal material serving as an intermediate layer from being diffused and allow element B of the first and second ferromagnetic layers to be diffused, the selective diffusion protecting layers are inserted between the ferromagnetic layer and the intermediate layer, so that the metal material of the intermediate layer may be prevented from being diffused and element B of the ferromagnetic layer may be allowed to be diffused into the intermediate layer when a high-temperature treatment is performed. Therefore, there are may be provided an MTJ structure with perpendicular magnetic anisotropy of which the thermal stability at high temperature is improved and a magnetic element including the same.

Description

[0001] The present invention relates to an MTJ structure having a perpendicular magnetic anisotropy and a magnetic element including the MTJ structure.

The present invention relates to an MTJ structure having perpendicular magnetic anisotropy, and more particularly, to an MTJ structure having perpendicular magnetic anisotropy including a free layer of a double ferromagnetic layer structure having thermal stability even at high temperatures and a magnetic element including the same.

A next generation nonvolatile memory that is attracting attention as a demand for a new information storage medium includes a ferroelectric memory (FeRAM), a magnetic memory (MRAM), a resistance memory (ReRAM), a phase change memory (PRAM) and the like. These memories have advantages of each, and research and development are proceeding actively in accordance with the purpose.

Among them, MRAM (Magnetic Random Access Memory) is a memory device which utilizes the quantum mechanical effect called magnetoresistance and is a device capable of storing non-volatile data with a feature of high density and high response with low power consumption. Which can replace the DRAM, which is a storage element that is being used.

Two effects of magnetoresistive effect, giant magnetoresistive (GMR) and tunneling magnetoresistive (TMR), are known.

An element using the GMR effect stores information by using a phenomenon that the resistance of a conductor located between two ferromagnetic layers changes according to the spin direction of the upper and lower ferromagnetic layers. However, the GMR element has a low MR (magnetoresistance) ratio, which indicates a ratio of the change in the magnetoresistance, to as low as about 10%. Therefore, the read signal of the stored information is small, and securing of the read margin is the greatest challenge in MRAM realization.

On the other hand, as a typical device using the TMR effect, a magnetic tunnel junction (MTJ) device using a change in magnetoresistance due to a magnetic tunnel junction effect is known.

This MTJ element has a stacked structure of a ferromagnetic layer / an insulating layer / a ferromagnetic layer. In the MTJ element, when the spin directions of the upper and lower ferromagnetic layers are the same, the tunnel probability between two ferromagnetic layers with the tunnel insulating film interposed therebetween is maximized, resulting in a minimum resistance value. On the other hand, when the spin direction is opposite, the tunnel probability is minimized and the resistance value becomes the maximum.

In order to realize these two spin states, either one of the ferromagnetic layers (the magnetic film) is set so that its magnetization direction is fixed and is not influenced by external magnetization. In general, a ferromagnetic layer having a fixed magnetization direction is referred to as a pinned layer.

The magnetization direction of the other ferromagnetic layer (magnetic film) can be the same as or opposite to the magnetization direction of the fixed layer depending on the direction of the applied magnetic field. The ferromagnetic layer at this time is generally referred to as a free layer and is responsible for storing information.

In the case of the MTJ element, the MR ratio as the rate of change in resistance is now more than 50%, and it is becoming the mainstream of MRAM development.

On the other hand, an MTJ element using a perpendicular magnetic anisotropic material is attracting attention.

Particularly, studies for applying an MTJ element using such a perpendicular magnetic anisotropic material to a vertical spin transfer torque-type magnetoresistive memory (STT-MRAM) have been actively conducted.

The spin transfer torque-type recording system refers to a method of inducing magnetization inversion by injecting a direct current into a magnetic tunnel junction, not an external magnetic field. This STT recording method is advantageous for high integration because no external conductor is required.

CoFeB is a material used for the magnetic tunnel junction using perpendicular magnetic anisotropy as described above. However, it has been studied as a horizontal magnetic anisotropic material. However, it has a characteristic of exhibiting perpendicular magnetic anisotropy at a very thin thickness (approximately 1.5 nm or less) Have been discovered and actively studied.

In the MTJ structure of CoFeB / MgO / CoFeB, which is a core part of the STT-MRAM, CoFeB used as a free layer and a fixed layer is a single thin film that exhibits perpendicular magnetic anisotropy at a very thin thickness, The problem of low stability is being raised.

In order to solve the thermal stability problem, a new method of increasing the thermal stability by replacing CoFeB single layer with CoFeB / metal layer / CoFeB has recently been proposed. In order to exhibit perpendicular magnetic anisotropy in a double ferromagnetic layer structure using such a double CoFeB thin film, crystallinity and uniformity of a metal layer inserted between CoFeB layers are important. However, there is a problem that the perpendicular magnetic anisotropy can be expressed by the double ferromagnetic layer structure when the metal layer is basically inserted into the ultra thin film.

Such an ultra-thin metal layer is poor in thermal stability, and diffuses into CoFeB as it is subjected to a high-temperature heat treatment to be contaminated, or even the metal layer itself may collapse.

Korean Patent Publication No. 10-2005-0018396

It is an object of the present invention to provide an MTJ structure having perpendicular magnetic anisotropy including a free layer of a double ferromagnetic layer structure having thermal stability at a high temperature and a magnetic element including the MTJ structure.

According to an aspect of the present invention, there is provided an MTJ structure having vertical magnetic anisotropy. This MTJ structure is a MTJ structure having a perpendicular magnetic anisotropy in which a pinned layer, a tunneling barrier layer and a free layer are sequentially stacked on a substrate, the free layer comprising a first ferromagnetic layer containing a ferromagnetic material containing element B, And a second ferromagnetic layer positioned on the ferromagnetic layer and comprising a ferromagnetic material, the intermediate layer comprising a metal material and the B element, the second ferromagnetic layer being located on the intermediate layer, wherein the free layer is disposed between the first ferromagnetic layer and the intermediate layer And a second selective diffusion preventing layer disposed between the intermediate layer and the second ferromagnetic layer, wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer are made of a material selected from the group consisting of And diffusion of element B of the first ferromagnetic layer and the second ferromagnetic layer is allowed.

Here, the first selective diffusion preventing layer and the second selective diffusion preventing layer include a material having a Gibbs free energy of-350 kJ / mol or more.

In addition, the first selective diffusion preventing layer and the second selective diffusion preventing layer may include TaN, TiN, or WN.

The thickness of the first selective diffusion preventing layer and the second selective diffusion preventing layer is 0.2 nm to 0.8 nm.

The intermediate layer may include Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Tc, Ru, Pd, La, Hf, Ta, W, Ir or Pt or an alloy thereof.

The first ferromagnetic layer and the second ferromagnetic layer may include a CoFeB material.

The conductive layer may further include a conductive oxide layer disposed on the free layer. The conductive oxide layer may include MgO.

The pinned layer may include an anti-ferromagnetic layer, a metal layer on the anti-ferromagnetic layer, and a ferromagnetic layer on the metal layer.

Also, the tunneling barrier layer may include at least one selected from the group consisting of MgO, Al 2 O 3 , HfO 2 , TiO 2 , Y 2 O 3, and Yb 2 O 3 .

According to another aspect of the present invention, there is provided an MTJ structure having vertical magnetic anisotropy. The MTJ structure having perpendicular magnetic anisotropy is a MTJ structure having a perpendicular magnetic anisotropy in which a free layer, a tunneling barrier layer, and a pinned layer are sequentially stacked on a substrate, and the free layer has a first ferromagnetic property including a ferromagnetic material including a B element And a second ferromagnetic layer positioned on the first ferromagnetic layer and including a ferromagnetic material located on the intermediate layer and containing an element B, the free layer having a first ferromagnetic And a second selective diffusion preventing layer disposed between the intermediate layer and the second ferromagnetic layer, wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer are formed on the intermediate layer, Diffusion of the metal material is prevented and diffusion of element B of the first ferromagnetic layer and the second ferromagnetic layer is permitted.

The first selective diffusion preventing layer and the second selective diffusion preventing layer include a material having a Gibbs free energy of-350 kJ / mol or more.

In addition, the first selective diffusion preventing layer and the second selective diffusion preventing layer may include TaN, TiN, or WN.

The thickness of the first selective diffusion preventing layer and the second selective diffusion preventing layer is 0.2 nm to 0.8 nm.

The intermediate layer may include Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Tc, Ru, Pd, La, Hf, Ta, W, Ir or Pt or an alloy thereof.

The substrate may further include a conductive oxide layer disposed between the substrate and the free layer. The conductive oxide layer may include MgO.

According to another aspect of the present invention, there is provided a magnetic element. The magnetic element may include a plurality of digit lines, a plurality of bit lines crossing over the digit lines, and the MTJ structure interposed between the digit line and the bit line.

According to the present invention, by inserting the selective diffusion preventing layer between the ferromagnetic layer and the intermediate layer in the free layer of the double ferromagnetic layer structure, it is possible to prevent the diffusion of the metal material of the intermediate layer into the ferromagnetic layer during the high- The spread of In addition, since the selective diffusion prevention layer to be inserted diffuses at a high temperature above the process temperature, self diffusion can be prevented, and penetration into the adjacent ferromagnetic layer does not occur, so that additional crystallinity can be secured.

Accordingly, it is possible to provide a perpendicular magnetic anisotropy MTJ structure having improved thermal stability even at a high temperature and a magnetic element including the MTJ structure.

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned can be clearly understood by those skilled in the art from the following description.

1 is a cross-sectional view of an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention.
2 is a cross-sectional view of an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. Rather, the intention is not to limit the invention to the particular forms disclosed, but rather, the invention includes all modifications, equivalents and substitutions that are consistent with the spirit of the invention as defined by the claims.

It will be appreciated that when an element such as a layer, region or substrate is referred to as being present on another element "on," it may be directly on the other element or there may be an intermediate element in between .

Although the terms first, second, etc. may be used to describe various elements, components, regions, layers and / or regions, such elements, components, regions, layers and / And should not be limited by these terms.

The term "A / B / C structure" used in the present invention means a structure in which a B layer and a C layer are sequentially stacked on an A layer.

The term "[A / B] n structure" used in the present invention means a structure in which A layer and B layer are alternately repeated n times. At this time, n is an integer of 1 or more.

1 is a cross-sectional view of an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention. The structure of FIG. 1 is a bottom pinned structure in which the fixed layer is located at the bottom.

Referring to FIG. 1, an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention includes a substrate 100, a pinned layer 200, a tunneling barrier layer 300, a free layer 400, and a conductive oxide layer 500 ).

The substrate 100 may be a substrate of various known materials. For example, such a substrate 100 may be embodied as a silicon substrate. Also, such a substrate 100 may be embodied as an electrode. On the other hand, such a substrate 100 may be omitted in some cases.

The pinned layer 200 is located on the substrate 100. The magnetization direction of the pinned layer 200 is fixed and is set so as not to be influenced by external magnetization.

The pinned layer 200 may include an antiferromagnetic layer 210, a metal layer 220 disposed on the antiferromagnetic layer 210, and a ferromagnetic layer 230 disposed on the metal layer 220.

The antiferromagnetic layer 210 serves to fix the magnetization direction of the ferromagnetic layer 230 described later. The anti-ferromagnetic layer 210 may be, for example, an artificial anti-ferromagnetic layer (SyAF). For example, such an artificial antiferromagnetic layer may be of a L 1 / Ru / L 1 structure in which Ru is interposed between ferromagnetic layers such as CoPd, CoPt, [Co / Pd] or [Co / Pt]. For example, the anisotropic antiferromagnetic layer may be a CoPd / Ru / CoPd structure.

The antiferromagnetic layer 210 may be formed through a conventional deposition method. For example, physical vapor deposition, chemical vapor deposition or sputtering is possible.

The metal layer 220 serves as a seed layer between the antiferromagnetic layer 210 and the ferromagnetic layer 230 and serves as a seed layer of the ferromagnetic layer 230. When the ferromagnetic layer 230 described later is a CoFeB layer, the metal layer 220 absorbs the boron (B) element of the ferromagnetic layer 230, which will be described later, when inducing a perpendicular magnetic anisotropy .

For example, the metal layer 220 may include any one selected from the group consisting of Ta, Ti, Nb, Zr, Hr, W, Pt, Pd and Ru or an alloy thereof.

The ferromagnetic layer 230 is located on the metal layer 220. The ferromagnetic layer 230 is made of a ferromagnetic material having perpendicular magnetic anisotropy.

For example, the ferromagnetic layer 230 may be made of at least one selected from the group consisting of Fe, Co, Ni, B, Si, Zr, Pt, Tb, Pd, Cu, W, Ta, One can be included.

For example, the ferromagnetic layer 230 may comprise CoFeB. The ferromagnetic layer containing CoFeB may be formed to a thickness of 1.5 nm or less to have perpendicular magnetic anisotropy.

This ferromagnetic layer 230 may be formed through a conventional deposition method. For example, physical vapor deposition, chemical vapor deposition or sputtering is possible.

Meanwhile, the ferromagnetic layer 230 may have perpendicular magnetic anisotropy at the time of forming the layer, but may have vertical magnetic anisotropy through a technique such as heat treatment after the formation of the layer.

The tunneling barrier layer 300 is located on this pinned layer 200. That is, the tunneling barrier layer 300 is interposed between the pinned layer 200 and a free layer 400 described later.

The material of such a tunneling barrier layer 300 may be any material that is an insulating material. For example, such an insulating material may be at least one selected from the group consisting of MgO, Al 2 O 3, HfO 2, TiO 2, Y 2 O 3 and Yb 2 O 3. Preferably, the tunneling barrier layer 300 may be a MgO layer.

This tunneling barrier layer 300 may be formed through a conventional deposition method. For example, physical vapor deposition, chemical vapor deposition or sputtering is possible.

The free layer 400 is located on this tunneling barrier layer 300. At this time, the free layer 400 may be a double ferromagnetic layer structure including two ferromagnetic layers.

1, the free layer 400 includes a first ferromagnetic layer 410, a first selective diffusion prevention layer 420, an intermediate layer 430, a second selective diffusion prevention layer 440, and a second And a ferromagnetic layer 450.

In other words, the free layer 400 includes a first ferromagnetic layer 410 including a ferromagnetic material including a boron (B) element, an intermediate layer 430 located on the first ferromagnetic layer 410 and including a metal material, And a second ferromagnetic layer (450) on the intermediate layer (430) and including a ferromagnetic material including element B, wherein the first ferromagnetic layer (410) and the intermediate layer (430) A selective diffusion prevention layer 420 and a second selective diffusion prevention layer 440 interposed between the intermediate layer 430 and the second ferromagnetic layer 450.

The first selective diffusion prevention layer 420 and the second selective diffusion prevention layer 440 prevent diffusion of the metal material of the intermediate layer 430 and prevent diffusion of the first ferromagnetic layer 410 and the second ferromagnetic layer 450, The diffusion of the element B of the element B is permitted.

The first ferromagnetic layer 410 is located on the tunneling barrier layer 300. The first ferromagnetic layer 410 may include a ferromagnetic material including an element B. [ For example, this first ferromagnetic layer 410 may comprise CoFeB. At this time, the CoFeB layer can be set to a thin thickness to have perpendicular magnetic anisotropy. For example, in order to have perpendicular magnetic anisotropy, the thickness of the CoFeB layer may be set to 1.5 nm or less.

The first ferromagnetic layer 410 may be formed through a conventional deposition method. For example, a physical vapor deposition method, a chemical vapor deposition method, a sputtering method, or a solution processing method is available.

The first selective diffusion prevention layer 420 is located on the first ferromagnetic layer 410. That is, the first selective diffusion preventing layer 420 is interposed between the first ferromagnetic layer 410 and an intermediate layer 430 described later.

The B element of the first ferromagnetic layer 410 is absorbed into the intermediate layer 430 during the high temperature annealing process at a temperature of 250 ° C. or more in the dual ferromagnetic layer structure, so that the perpendicular magnetic anisotropy of the first ferromagnetic layer 410 can be expressed. However, during the high-temperature annealing process, the metal material of the intermediate layer 430 may diffuse into the first ferromagnetic layer 410 to cause a problem of contaminating the first ferromagnetic layer 410.

Therefore, in the present invention, it is possible to prevent the diffusion of the metal material of the intermediate layer 430 between the first ferromagnetic layer 410 and the intermediate layer 430 and to prevent diffusion of the B element of the first ferromagnetic layer 410, Diffusion preventing layer 420 was inserted.

Diffusion of the element B of the first ferromagnetic layer 410 into the intermediate layer 430 is allowed by the insertion of the first selective diffusion preventing layer 420 so that the element B is absorbed by the intermediate layer 430, It is possible to prevent the metal material of the intermediate layer 430 from diffusing into the first ferromagnetic layer 410 while at the same time maintaining the perpendicular magnetic anisotropy of the layer 410 and preventing the magnetic properties of the first ferromagnetic layer 410 from collapsing Can be prevented.

The first selective diffusion preventing layer 420 may include a material having a Gibbs free energy of not less than about 350 kJ / mol. The Gibbs free energy value at this time means a value under known standard conditions.

When a material having a Gibbs free energy of greater than or equal to about 350 kJ / mol is used as a selective diffusion preventing layer material, the metal material of the intermediate layer 430, which is relatively large and heavy at a target temperature (about 350 ° C. to 425 ° C.) Diffusion can be prevented and diffusion of boron (B), which is a relatively small diffusion element, can be tolerated.

This is because the diffusion of B is allowed because diffusion of atoms such as B, which are small in size by weak bonds, is possible in the case of a substance having a Gibbs free energy of-350 kJ / mol or more.

For example, the first selective diffusion preventing layer 420 may include TaN, TiN, or WN. For example, a TiN material is a material with a Gibbs free energy of about -309.62 kJ / mol. Also, the unstable Bar Gibbs free energy of the WN and TaN materials compared to the TiN material will be larger than the value of TiN.

In addition, the thickness of the first selective diffusion preventing layer 420 may be 0.2 nm to 0.8 nm. If the thickness of the first selective diffusion preventing layer 420 is less than 0.2 nm, the first selective diffusion preventing layer 420 may not grow as a whole and the diffusion of the metal material of the intermediate layer 430 may not be prevented . If the thickness of the first selective diffusion prevention layer 420 exceeds 0.8 nm, the nitrogen of the first selective diffusion prevention layer 420 may lower the quality of the magnetic layer and cause a problem that the magnetic moment becomes small.

The first selective diffusion preventing layer 420 may be formed through a conventional deposition method. For example, physical vapor deposition, chemical vapor deposition or sputtering is possible.

The intermediate layer 430 is located on the first selective diffusion prevention layer 420. The intermediate layer 430 may include a metal material. The metal material used for the intermediate layer 430 may include a first ferromagnetic layer 410 and a second ferromagnetic layer 450 so as to exhibit perpendicular magnetic anisotropy of the first ferromagnetic layer 410 and the second ferromagnetic layer 450, It is preferable to select a substance capable of absorbing the element B of FIG.

For example, the intermediate layer 430 may include at least one of Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Tc, Ru, Pd, La, Hf, Ta, W, Ir, Pt, can do.

For example, the first ferromagnetic layer may be a CoFeB layer and the intermediate layer 430 may be a Ta layer. In this case, when the Ta layer absorbs the B element of the CoFeB layer during the high-temperature heat treatment, the perpendicular magnetic anisotropy of the first ferromagnetic layer can be induced.

Further, the intermediate layer 430 can be set to a thickness of 0.2 nm to 1.0 nm.

The intermediate layer 430 may be formed by a conventional deposition method. For example, physical vapor deposition, chemical vapor deposition or sputtering is possible.

The second selective diffusion prevention layer 440 is located on the intermediate layer 430. That is, the second selective diffusion preventing layer 440 is interposed between the intermediate layer 430 and the second ferromagnetic layer 450 described later.

Therefore, the second selective diffusion preventing layer 440 allows diffusion of the boron (B) element of the second ferromagnetic layer 450 to the intermediate layer 430, so that the element B is absorbed into the intermediate layer 430, 450 while preventing the metal material of the intermediate layer 430 from diffusing into the first ferromagnetic layer 450 to prevent the magnetic properties of the second ferromagnetic layer 450 from collapsing can do.

The second selective diffusion preventing layer 440 may include a material having a Gibbs free energy of-350 kJ / mol or more. The Gibbs free energy value at this time means a value under known standard conditions.

When a material with a Gibbs free energy of greater than or equal to 350 kJ / mol is used as a selective diffusion barrier material, the diffusion of the metal material in the intermediate layer, which is relatively large and heavy at the target temperature (about 350 ° C. to 425 ° C.) And diffusion of boron (B), which is a relatively small diffusible element, can be tolerated.

This is because the diffusion of B is allowed because diffusion of atoms such as B, which are small in size by weak bonds, is possible in the case of a substance having a Gibbs free energy of-350 kJ / mol or more.

For example, the second selective diffusion preventing layer 440 may include TaN, TiN, or WN. For example, a TiN material is a material with a Gibbs free energy of about -309.62 kJ / mol. Also, the unstable Bar Gibbs free energy of the WN and TaN materials compared to the TiN material will be larger than the value of TiN.

In addition, the thickness of the second selective diffusion preventing layer 440 may be 0.2 nm to 0.8 nm. If the thickness of the second selective diffusion preventing layer 440 is less than 0.2 nm, the second selective diffusion preventing layer 440 may not grow as a whole and the diffusion of the metal material of the intermediate layer 430 may not be prevented . If the thickness of the second selective diffusion prevention layer 440 is more than 0.8 nm, the nitrogen of the second selective diffusion prevention layer 440 may lower the quality of the magnetic layer and cause a problem that the magnetic moment becomes small.

The second selective diffusion preventing layer 440 may be formed through a conventional deposition method. For example, physical vapor deposition, chemical vapor deposition or sputtering is possible.

The second ferromagnetic layer 450 is located on the second selective diffusion prevention layer 440. The second ferromagnetic layer 450 may include a ferromagnetic material including element B. [ For example, this second ferromagnetic layer 450 may comprise CoFeB. At this time, the CoFeB layer can be set to a thin thickness to have perpendicular magnetic anisotropy. For example, in order to have perpendicular magnetic anisotropy, the thickness of the CoFeB layer may be set to 1.5 nm or less.

The second ferromagnetic layer 450 may be formed through a conventional deposition method. For example, a physical vapor deposition method, a chemical vapor deposition method, a sputtering method, or a solution processing method is available.

The conductive oxide layer 500 is located on the free layer 400. The conductive oxide layer 500 may include MgO.

The first ferromagnetic layer 410 located under the free layer 400 during the high temperature annealing may contact the tunneling barrier layer 300 to exhibit vertical magnetic anisotropy during the high temperature annealing process, May not contact the tunneling barrier layer 300 and may be difficult to exhibit perpendicular magnetic anisotropy. Accordingly, by placing the conductive oxide layer 500 on the free layer 400, the second ferromagnetic layer 450 and the conductive oxide layer 500 can be brought into contact with each other, and the perpendicular magnetic anisotropy can be effectively exhibited during the high-temperature heat treatment.

2 is a cross-sectional view of an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention.

Referring to FIG. 2, an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention includes a substrate 100, a conductive oxide layer 500, a free layer 400, a tunneling barrier layer 300, ).

The MTJ structure of FIG. 2 is a top pinned structure in which the fixed layer is located at the top. The structure of FIG. 2 differs from the MTJ structure of FIG. 1 only in the structure. A detailed description of each constituent layer is the same as that described above with reference to FIG. 1, and only the structure of FIG. 2 will be described below .

The substrate 100 may be a substrate of various known materials.

The conductive oxide layer 500 is also located on the substrate 100. The conductive oxide layer 500 is in contact with the first ferromagnetic layer 410 of the free layer 400 to be described later so that the first ferromagnetic layer 410 exhibits perpendicular magnetic anisotropy during the high temperature heat treatment.

The free layer 400 is located on the conductive oxide layer 500. At this time, the free layer 400 may be a double ferromagnetic layer structure including two ferromagnetic layers.

For example, as shown in FIG. 2, the free layer 400 includes a first ferromagnetic layer 410 comprising a ferromagnetic material including an element B, a first ferromagnetic layer 410 located on the first ferromagnetic layer 410, And a second ferromagnetic layer 450 disposed on the intermediate layer 430 and including a ferromagnetic material including an element B. [ The free layer 400 may include a first selective diffusion barrier layer 420 disposed between the first ferromagnetic layer 410 and the intermediate layer 430 and a second selective diffusion barrier layer 420 disposed between the intermediate layer 430 and the second ferromagnetic layer 450, The second selective diffusion preventing layer 440 may be formed on the second selective diffusion preventing layer 440.

The first selective diffusion prevention layer 420 and the second selective diffusion prevention layer 440 prevent diffusion of the metal material of the intermediate layer 430 and prevent diffusion of the first ferromagnetic layer 410 and the second ferromagnetic layer 450 ) Is allowed to be diffused.

In addition, the tunneling barrier layer 300 is located on the free layer 400.

The pinned layer 200 is also located on the tunneling barrier layer 300. The pinned layer 200 may include a ferromagnetic layer 230, a metal layer 220 disposed on the ferromagnetic layer, and an antiferromagnetic layer 210 disposed on the metal layer 220.

Hereinafter, a magnetic element including an MTJ structure having perpendicular magnetic anisotropy according to an embodiment of the present invention will be described.

Such a magnetic element may include a plurality of digit lines, a plurality of bit lines across the top of such digit lines, and a magnetic tunnel junction interposed between the digit line and the bit line. The magnetic tunnel junction at this time may be an MTJ structure having the perpendicular magnetic anisotropy described above with reference to FIG. 1 and FIG.

According to the present invention, by inserting the selective diffusion preventing layer between the ferromagnetic layer and the intermediate layer in the free layer of the double ferromagnetic layer structure, it is possible to prevent the diffusion of the metal material of the intermediate layer into the ferromagnetic layer during the high- The spread of

In addition, since the selective diffusion prevention layer to be inserted diffuses at a high temperature above the process temperature, self diffusion can be prevented, and penetration into the adjacent ferromagnetic layer does not occur, so that additional crystallinity can be secured.

Accordingly, it is possible to provide a perpendicular magnetic anisotropy MTJ structure having improved thermal stability even at a high temperature and a magnetic element including the MTJ structure.

It should be noted that the embodiments of the present invention disclosed in the present specification and drawings are only illustrative of specific examples for the purpose of understanding and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention are possible in addition to the embodiments disclosed herein.

100: substrate 200: fixed layer
210: antiferromagnetic layer 220: metal layer
230: ferromagnetic layer 300: tunneling barrier layer
400: free layer 410: first ferromagnetic layer
420: first selective diffusion preventing layer 430: intermediate layer
440: second selective diffusion preventing layer 450: second ferromagnetic layer
500: Conductive oxide layer

Claims (18)

An MTJ structure having perpendicular magnetic anisotropy in which a fixed layer, a tunneling barrier layer, and a free layer are sequentially stacked on a substrate,
Wherein the free layer comprises a first ferromagnetic layer comprising a ferromagnetic material comprising element B, an intermediate layer located on the first ferromagnetic layer and comprising a metallic material, and a ferromagnetic material located on the intermediate layer and comprising element B And a second ferromagnetic layer,
The free layer further includes a first selective diffusion preventing layer positioned between the first ferromagnetic layer and the intermediate layer and a second selective diffusion preventing layer positioned between the intermediate layer and the second ferromagnetic layer,
Wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer prevent diffusion of the metal material of the intermediate layer and permit diffusion of element B of the first ferromagnetic layer and the second ferromagnetic layer. MTJ structure with. The method according to claim 1,
Wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer include a material having a Gibbs free energy of-350 kJ / mol or more. The method according to claim 1,
Wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer have vertical magnetic anisotropy including TaN, TiN, or WN. The method according to claim 1,
Wherein the thickness of the first selective diffusion prevention layer and the second selective diffusion prevention layer is 0.2 nm to 0.8 nm. The method according to claim 1,
Wherein the intermediate layer has a perpendicular magnetic anisotropy including Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Tc, Ru, Pd, La, Hf, Ta, W, Ir, Pt, MTJ structure. The method according to claim 1,
Wherein the first ferromagnetic layer and the second ferromagnetic layer have vertical magnetic anisotropy including a CoFeB material. The method according to claim 1,
Further comprising a conductive oxide layer on the free layer. ≪ RTI ID = 0.0 > 18. < / RTI > 8. The method of claim 7,
Wherein the conductive oxide layer has vertical magnetic anisotropy including MgO. The method according to claim 1,
Wherein,
An MTJ structure having perpendicular magnetic anisotropy including an antiferromagnetic layer, a metal layer located on the antiferromagnetic layer, and a ferromagnetic layer located on the metal layer. The method according to claim 1,
Wherein the tunneling barrier layer includes at least one selected from the group consisting of MgO, Al 2 O 3 , HfO 2 , TiO 2 , Y 2 O 3, and Yb 2 O 3 . An MTJ structure having vertical magnetic anisotropy in which a free layer, a tunneling barrier layer, and a pinned layer are sequentially stacked on a substrate,
Wherein the free layer comprises a first ferromagnetic layer comprising a ferromagnetic material comprising element B, an intermediate layer located on the first ferromagnetic layer and comprising a metallic material, and a ferromagnetic material located on the intermediate layer and comprising element B And a second ferromagnetic layer,
The free layer further includes a first selective diffusion preventing layer positioned between the first ferromagnetic layer and the intermediate layer and a second selective diffusion preventing layer positioned between the intermediate layer and the second ferromagnetic layer,
Wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer prevent diffusion of the metal material of the intermediate layer and permit diffusion of element B of the first ferromagnetic layer and the second ferromagnetic layer. MTJ structure with. 12. The method of claim 11,
Wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer include a material having a Gibbs free energy of-350 kJ / mol or more. 12. The method of claim 11,
Wherein the first selective diffusion preventing layer and the second selective diffusion preventing layer have vertical magnetic anisotropy including TaN, TiN, or WN. 12. The method of claim 11,
Wherein the thickness of the first selective diffusion prevention layer and the second selective diffusion prevention layer is 0.2 nm to 0.8 nm. 12. The method of claim 11,
Wherein the intermediate layer has a perpendicular magnetic anisotropy including Sc, Ti, V, Cr, Mn, Y, Zr, Nb, Mo, Tc, Ru, Pd, La, Hf, Ta, W, Ir, Pt, MTJ structure. 12. The method of claim 11,
Further comprising a conductive oxide layer disposed between the substrate and the free layer. 17. The method of claim 16,
Wherein the conductive oxide layer has vertical magnetic anisotropy including MgO. A plurality of digit lines;
A plurality of bit lines across the top of the digit lines; And
And the MTJ structure according to any one of claims 1 to 17 interposed between the digit line and the bit line.
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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20050018396A (en) 2003-08-12 2005-02-23 삼성전자주식회사 Magnetic tunnel junction structures having a laminated free layer and magnetic random access memory cells employing the same
KR20070056903A (en) * 2005-11-30 2007-06-04 후지쯔 가부시끼가이샤 Magnetoresistive element, magnetic head, magnetic storage unit, and magnetic memory unit
KR20140131136A (en) * 2013-05-03 2014-11-12 삼성전자주식회사 Magnetic device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20050018396A (en) 2003-08-12 2005-02-23 삼성전자주식회사 Magnetic tunnel junction structures having a laminated free layer and magnetic random access memory cells employing the same
KR20070056903A (en) * 2005-11-30 2007-06-04 후지쯔 가부시끼가이샤 Magnetoresistive element, magnetic head, magnetic storage unit, and magnetic memory unit
KR20140131136A (en) * 2013-05-03 2014-11-12 삼성전자주식회사 Magnetic device

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