JP2014505375A - Magnetic tunnel junction device having an amorphous buffer layer that is magnetically coupled and has perpendicular magnetic anisotropy - Google Patents

Abstract

  Provided is a magnetic element having a buffer layer that is simple in structure and has a thin thickness while allowing magnetic coupling regardless of the size and structure of the crystal. The magnetic tunnel junction device according to the first embodiment of the present invention includes a free layer that can have magnetization in a variable direction, a fixed layer that has magnetization in a fixed direction, and a tunnel insulation formed between the free layer and the fixed layer. The fixed layer includes a magnetic film and an amorphous metal film. In addition, the magnetic element according to the second embodiment of the present invention includes an amorphous or nanocrystalline material layer and a perpendicular magnetic anisotropic material layer formed on the amorphous or nanocrystalline material layer. The amorphous or nanocrystalline material layer is formed on the lower layer as a predetermined amorphous material or nanocrystalline material layer, and the perpendicular magnetic anisotropic material layer is formed on the amorphous or nanocrystalline material layer. It is formed.

Description

  The present invention relates to a magnetic tunnel junction device, and more particularly, to a magnetic tunnel junction device including a fixed layer further including an amorphous metal film, and a fine magnetic device using a perpendicular magnetic anisotropic material.

  Industrial applicability has been concentrated in the field of spintronics since the mid-1990s. Here, spintronics is a compound word of 'spin + electronics'. In other words, the current electronics has studied only technology that uses 'charge', which is one of the two properties of electrons, but has a new function using 'spin', which is another property of electrons. I am trying to develop a device.

  The best way to use the spin of electrons is to use a ferromagnet. In particular, in the case of a magnetic tunnel junction element (MTJ) using a TMR (Tunneling Magneto Resistance: TMR) structure, since its applicable field is wide, it has attracted more attention recently.

  Here, the TMR structure refers to a ferromagnetic-insulating film-ferromagnetic structure, and the magnetic tunnel junction device uses the effect that the quantum mechanical tunneling current is influenced by the magnetization direction of the magnetic material. Thus, it can be utilized as a means for storing data. Here, because the principle that can be used as a data storage means is a magneto-resistance characteristic, this means a characteristic that the resistance changes according to the arrangement of the two ferromagnets.

  That is, the tunneling current is maximized when the magnetization directions of the two ferromagnets are parallel, and minimized when the magnetization directions are antiparallel. Ferromagnetic materials have different electron densities according to the spin direction.

  If the second ferromagnet is magnetized in the same direction as the first ferromagnet when electrons in the Fermi level of the ferromagnet pass through the insulating film, the two ferromagnets Since the spin directions that are easy to hold match, electrons move easily, but if ferromagnetic materials are arranged in opposite directions, scattering of tunneling electrons will occur, and the resistance will increase. It becomes like this.

  At this time, the tunnel ring insulating film is preferably selected so that a material capable of obtaining a high magnetoresistance ratio (MR ratio) is selected. For this reason, MgO has recently attracted attention as a new insulating film.

  In addition to the high MR ratio, the uniformity of magnetoresistance is an important factor in determining the characteristics of the magnetic tunnel junction device. For this purpose, it is important to form the thickness of each film uniformly. In particular, it is important that the thickness of the tunnel insulating film is formed flat during the heat treatment step.

  However, in the case of the conventional magnetic tunnel junction element, it has been reported that there are many problems in the uniformity of magnetoresistance. In other words, the flatness of the tunnel insulating film is deteriorated by the lower structure of the tunnel insulating film during the heat treatment process.

  The heat treatment process is an essential process for improving the characteristics of the magnetic material by crystallizing the tunnel insulating film and the ferromagnetic material. However, while the lower structure of the tunnel insulating film is crystallized, the lower structure becomes rough, but the tunnel insulating film formed on the upper portion of the lower structure is affected by this, and the flatness deteriorates. . Eventually, according to the conventional structure, even when formed on the same wafer, the characteristics of the magnetic tunnel junction elements are different from each other, so that the uniformity of the magnetic resistance cannot be ensured.

  Further, the conventional magnetic tunnel junction device has a problem that the tunnel insulating film can be contaminated by the lower structure when the heat treatment process is performed. In particular, for example, in the case of PtMn or IrMn used as the material of the antiferromagnetic layer (AFM), Mn particles are diffused toward the tunnel insulating film during the heat treatment process and are positioned at the interface of the tunnel insulating film. As a result, the tunnel insulating film is contaminated. In this case, the flatness of the tunnel insulating film is deteriorated, and eventually the uniformity of magnetoresistance is adversely affected.

  Accordingly, a magnetic tunnel junction device having a new structure that can improve uniformity when forming a substructure of a tunnel insulating film is required.

  Conventionally, in order to realize perpendicular anisotropy with a magnetic material, a monoatomic structure is used as a buffer, or a crystalline material is used as a buffer. As a result, a memory cell having a size of several tens of nanometers is formed by an STT-MRAM (Spin Transfer Torque-MRAM) using perpendicular magnetism in which grains having perpendicular anisotropy are formed in units of several micrometers. In some cases, when a cell is formed at a grain boundary, a possibility that a defective cell is generated increases.

  In addition, in the conventional perpendicular magnetic anisotropy control technology, in order to control the perpendicular magnetic anisotropy, there is a combination of a lattice constant of a substance having perpendicular magnetic anisotropy and a buffer layer that is perfect for the crystal direction. It was an essential element.

  However, in this case, the use of many buffer layers increases the thickness of the entire buffer layer, and only a specific material having a crystal size can be used. The use of a buffer layer has caused various process problems.

  Further, it is impossible to form a film on a material ordered in an L10 structure such as FePt or FePd that can be used as a pinned layer in the lower part.

  In order to solve the above-described problems, an object of the present invention is to improve the characteristics of a magnetic tunnel junction element by improving the non-uniformity of a tunnel insulating film that may occur during a heat treatment process.

  Another object of the present invention is to provide a magnetic element having a buffer layer that is simple in structure and has a thin thickness although magnetic coupling is possible regardless of the size and structure of the crystal. To do.

  In order to achieve the above-described object, a magnetic tunnel junction device according to an embodiment of the present invention includes a free layer that can have magnetization in a variable direction, a fixed layer that has magnetization in a fixed direction, and the free layer. And a tunnel insulating film formed between the pinned layer and the pinned layer, the pinned layer including a ferromagnetic film and an amorphous metal film.

  In addition, the magnetic tunnel junction device according to the second embodiment of the present invention includes an amorphous or nanocrystalline material layer and a perpendicular magnetic anisotropic material layer formed on the amorphous or nanocrystalline material layer. The amorphous or nanocrystal material layer is formed on the lower layer as a preset amorphous material or nanocrystal material layer, and the perpendicular magnetic anisotropic material layer is formed on the amorphous or crystal material layer. The

  As described above, an amorphous material or a nanocrystal material is used as a buffer for forming a perpendicular magnetic anisotropic material on the substrate or the lower layer having various layer structures formed on the substrate. Thus, a buffer that is simple in structure but independent of the size and structure of the crystal can be realized. Here, the buffer means the layer immediately below the vertically anisotropic material (or the upper layer when stacked oppositely).

  At this time, the amorphous buffer material preferably has a higher crystallization temperature than the perpendicular magnetic anisotropic material. As described above, when the crystallization temperature of the amorphous buffer material is higher than the crystallization temperature of the perpendicular magnetic anisotropy material, the perpendicular magnetic anisotropy material is crystallized. While the crystallization is not progressing, the layer maintains an amorphous state and performs an amorphous buffer role.

  Also, the amorphous material is an amorphous metal, and in particular can be FeZr. Thus, when an amorphous material is employed as the amorphous metal, electrical conduction is facilitated to the perpendicular magnetic anisotropic material layer through the buffer.

  The lower layer may be a perpendicular magnetic anisotropic material layer. Such a configuration allows magnetic coupling while blocking texture transmission between the lower part of the amorphous metal layer and the upper perpendicular magnetic anisotropic material layer.

  The lower layer may include an antiferromagnetic material layer. Such a configuration enables a spin valve structure that uses the upper perpendicular magnetic anisotropic material layer as a fixed layer.

  When the magnetic tunnel junction device is manufactured according to the first embodiment of the present invention, the non-uniformity of the tunnel insulating film that may occur during the heat treatment process can be improved, and the antiferromagnetic material that can be formed below the fixed layer. Since the diffusion of body particles is prevented, the uniformity of magnetoresistance can be improved. As a result, the characteristics of the magnetic tunnel junction element can be greatly improved.

  In addition, according to the second embodiment of the present invention, as a result of inserting the FeZr single layer into the thin amorphous buffer layer, the perpendicular magnetic anisotropy is observed in the CoFeB layer adjacent to the MgO layer after the heat treatment. Can be confirmed.

  In addition, since the buffer layer is thin, it is possible to prevent damage to the sample that may occur in a long etching process due to the use of a thick buffer layer in the etching process after stacking. it can.

  In addition, when a single layer material having a high crystallization temperature is used as a buffer layer (morphology buffer layer), the temperature of the heat treatment temperature due to the crystallization of the buffer layer is generally increased during high temperature heat treatment due to perpendicular magnetic anisotropy. You can overcome the limitations.

  Further, since the buffer layer is in an amorphous state, a perpendicular magnetic anisotropic material having a different lattice constant can be used as the buffer layer regardless of the size of the crystal. it can. Therefore, the desired perpendicular magnetic anisotropy can be realized regardless of the texture of the lower electrode.

  In addition, a CoFeB layer (layer) having perpendicular magnetic anisotropy can be implemented on a pinned layer having strong perpendicular magnetic anisotropy.

  The structure of the present invention is similarly applied when the order of forming the multilayer thin film is reversed.

It is the schematic with respect to the structure of a general magnetic tunnel junction element. 1 is a diagram for explaining the structure of a magnetic tunnel junction device proposed according to a first embodiment of the present invention; It is an experimental data for demonstrating the effect in case FeZr is included in the fixed layer of FIG. FIG. 6 is a schematic cross-sectional view of one embodiment of a magnetic element according to a second embodiment of the present invention. 5 is a drawing showing VSM data showing a change in magnetization after heat treatment at 400 ° C. for a sample having the structure of FIG. 4. FIG. 6 is a schematic cross-sectional view of another embodiment of a magnetic element according to a second embodiment of the present invention. FIG. 6 is a schematic cross-sectional view of an embodiment of a magnetic element according to a second embodiment of the present invention including a spin valve structure. 6 is a schematic flowchart for performing an embodiment of a method for manufacturing the magnetic element of FIG. 4. 6 is a diagram showing data obtained by measuring the magnitude of perpendicular magnetic anisotropy according to the thickness of CoFeB in the structure of FIG. 4. 5 is a diagram illustrating data obtained by measuring the magnitude of perpendicular magnetic anisotropy according to the thickness of FeZr in the structure of FIG. 4.

  In the following, the most preferred embodiment of the present invention will be described. In the drawings, thicknesses and spacings are expressed for ease of explanation and may be exaggerated relative to the actual physical thickness. In describing the present invention, known configurations that are not related to the gist of the present invention may be omitted.

  It should be noted that the reference numbers are added to the components of each drawing so that the same components have the same number as much as possible even if they are displayed on other drawings. .

  FIG. 1 is a schematic view illustrating a structure of a general magnetic tunnel junction element. In general, the magnetization direction of one of the two ferromagnetic layers is fixed. This is called a pinned layer (PL), and the remaining one is called a free layer (FL) whose magnetization direction is changed by an external magnetic field or a penetrating current. Here, the arrow indicates the magnetization direction. As shown, the magnetization direction of the fixed layer PL is fixed, but the free layer FL can be magnetized in a variable direction.

  In general, the fixed layer PL is used together with an antiferromagnetic layer (AFM) such as PtMn, IrMn, etc., so that the magnetization direction is less likely to change compared to the free layer FL. The antiferromagnetic layer (AFM) completely separates the magnetic field region necessary for the magnetization reversal of the fixed layer PL from the free layer FL, thereby reversing the magnetization of the fixed layer PL in the external magnetic field region corresponding to the actual use range. And only the free layer FL can reverse the magnetization.

  Eventually, the interlayer structure of the magnetic tunnel junction element is designed so that the two ferromagnetic layers can only have two states of relatively parallel magnetization directions or antiparallel magnetization directions. As a result, not only the optimum TMR value can be obtained, but also the stability of the signal can be increased.

  FIG. 2 is a view for explaining the structure of the magnetic tunnel junction device proposed by the first embodiment of the present invention. In order to simplify the description, the ferromagnetic layer and the diamagnetic layer are mainly illustrated.

  As described above, the magnetic tunnel junction element basically has a structure of “ferromagnetic material-insulating film-ferromagnetic material”. One is formed so that the magnetization is fixed, and the other is formed so that the magnetization can be varied. For convenience, the former is a fixed layer, the latter is a free layer, and the tunneling current differs depending on whether the magnetization directions of the two ferromagnets are parallel or antiparallel. As a role.

  Here, the material constituting the ferromagnetic material is preferably a substance that can ensure a high MR ratio, and can include CoFe or CoFeB.

  The magnetic tunnel junction device of the present invention includes a free layer FL that can have magnetization in a variable direction on a substrate (not shown), a fixed layer PL that has magnetization in a fixed direction, and the free layer FL and the fixed layer PL. The fixed layer PL includes magnetic films PL_1 and PL_2 and an amorphous metal film 21.

  Here, the crystallization temperature of the amorphous metal film 21 is preferably higher than those of the ferromagnetic films PL_1 and PL_2 and the tunnel insulating film.

  In addition, the ferromagnetic film PL_1, the amorphous metal film 21, and the ferromagnetic film PL_2 of the fixed layer PL may include a stacked structure.

  The present invention does not have a composite antiferromagnetic structure as in the prior art, but the fixed layer PL includes “ferromagnetic material PL_1-amorphous metal film 21 having a high crystallization temperature—ferromagnetic material PL_2”. A distinction is made from conventional technology.

  By including the amorphous metal film 21 in the fixed layer PL formed below the tunnel insulating film as in the present invention, the ferromagnetic material PL_1 and the ferromagnetic material PL_2 can be crystallized through the heat treatment process. The amorphous metal film 21 can be grown to a constant thickness. That is, the roughness of the lower structure of the tunnel insulating film can be greatly reduced. As a result, the tunnel insulating film can be formed flat, and the uniformity of magnetoresistance can be greatly improved. .

  On the other hand, the antiferromagnetic layer (AFM) is formed below the fixed layer PL in order to fix the magnetization of the fixed layer PL as described above. In this case, the material of the antiferromagnetic layer (AFM) may diffuse into the fixed layer PL during the heat treatment process and contaminate the tunnel insulating film.

  When the tunnel insulating film is contaminated, the tunneling current of the magnetic tunnel junction varies according to the degree of contamination, so that the uniformity of magnetoresistance deteriorates.

  However, when the fixed layer PL includes the amorphous metal film 21 having a high crystallization temperature as in the present invention, the phenomenon as described above can be prevented. That is, even if the heat treatment process proceeds, since the crystallization temperature of the amorphous metal film 21 is high, the amorphous state is maintained and the amorphous metal film 21 exists between the fixed layers PL. It becomes difficult for the material of the magnetic layer (AFM) to pass through the amorphous metal film 21.

  In addition, the amorphous metal film as in the present invention can include a magnetic material. Therefore, in this case, it is not necessary to adjust the fine thickness.

  Conventionally, a “ferromagnetic-Ru-ferromagnetic” composite anti-ferromagnetic structure has been used to block a stray field of a magnetic material. In this case, the thickness of the insertion layer “Ru” must be very finely adjusted.

  That is, there is a disadvantage in that the characteristics of the entire device change while the characteristics of magnetic coupling change depending on the thickness of Ru. Therefore, a change in the thickness of Ru due to the diffusion of Ru during the heat treatment process may cause a change in the switching characteristics of the device.

  However, the present invention is not mainly intended to block the stray field of the magnetic material, but aims to form the tunnel insulating film flat as described above. Therefore, the fixed layer of the present invention includes a ferromagnetic film and an amorphous metal film. It is desirable to include a laminated structure in which an amorphous metal film is formed between the ferromagnetic films as described above.

  Therefore, the present invention does not need to adjust the fine thickness as described above. However, the amorphous metal film can be formed as thick as the ferromagnetic films PL_1 and PL_2 or more if necessary. In this case, the flatness of the tunnel insulating film is improved, and the diffusion of the antiferromagnetic layer (AFM) material formed below can be blocked.

  As an example, it is as follows. As described above, CoFe or CoFeB can be used as the ferromagnetic layer material of the magnetic tunnel junction element. PtMn or IrMn can be used as the material of the antiferromagnetic layer (AFM) that fixes the magnetization of the fixed layer PL.

  In order to simplify the explanation, an example will be described in which CoFeB is used as the ferromagnetic layer and IrMn is used as the material of the antiferromagnetic layer. In addition, although the tunnel insulating film is preferably made of MgO, it should be noted that other materials may be used for the material as described above according to the development of related technology.

  In this case, each material is crystallized step by step through the heat treatment process. As in the present invention, when the magnetic tunnel junction element is formed in “CoFeB—MgO—CoFeB—amorphous metal film 21—CoFeB having a high crystallization temperature”, it is included until CoFeB is crystallized. Since the amorphous metal film 21 is not crystallized, the diffusion of Mn particles can be prevented.

  Then, as described above, the material of the amorphous metal film 21 having a high crystallization temperature can be a problem. Here, since the amorphous metal film 21 must have a high crystallization temperature and is a material included in the fixed layer PL, it can include the properties of a magnetic substance.

  In this case, the amorphous metal film 21 can include FeZr. However, although FeZr has been presented herein, it should be noted that such materials may be used with other compatible materials as the related art develops.

  That is, even when CoFeB is crystallized into a bcc structure or an fcc structure, FeZr is not crystallized and exists in an amorphous state even if it is crystallized into a bcc structure or an fcc structure. Further, since FeZr can have three magnetic characteristics according to the ratio of Fe and Zr: ferromagnetism, paramagnetism, and weak ferromagnetism, it is widely used in the manufacture of magnetic tunnel junction elements. FeZr is very advantageous in the process because it is not necessary to adjust the fine thickness.

FIG. 3 shows experimental data for explaining the effect when FeZr is included in the fixed layer PL. In the experiment, seven magnetic tunnel junction elements were formed on a 12.5 mm × 12.5 mm SiO _x wafer. Then, an external magnetic field of 4 kOe was applied to grow the tunnel insulating film MgO, and a heat treatment process was performed at 270 ° C. for 10 minutes. Each TMR was measured at room temperature by a four-terminal measurement method using a direct current source for the magnetic tunnel junction element.

  As shown, when the fixed layer PL does not include FeZr (41), the TMR distribution of the seven magnetic tunnel junction elements is very wide (D1). However, the TMR distribution becomes very narrow (D2) when 5% of FeZr is included (42) and when 10% of FeZr is included (43).

  Thus, by including FeZr in the fixed layer PL, the uniformity of the magnetoresistance is greatly improved, thereby ensuring reliability in the manufacture and operation of the magnetic tunnel junction element.

  FIG. 4 is a schematic cross-sectional view of one embodiment of a magnetic element according to the second embodiment of the present invention. In FIG. 4, in order to make a CoFeB magnetic material having a horizontal magnetic anisotropy generally have a perpendicular magnetic anisotropy, a perpendicular magnetic anisotropy is used by using a FeZr amorphous morphological buffer layer. The laminated structure of the sample that has anisotropy is illustrated.

  Here, the morphological buffer layer refers to a layer that prevents a texture collision by causing a texture to propagate to the upper and lower adjacent thin film layers, or blocks an unwanted texture propagation. .

  In FIG. 4, the magnetic element includes an amorphous material layer 110 and a perpendicular magnetic anisotropic material layer 120 formed on the amorphous material layer 110. The amorphous material layer 110 is formed on the lower layer 130 as a predetermined amorphous material layer, and the perpendicular magnetic anisotropic material layer 120 is formed on the amorphous material layer 110.

  Although an amorphous material is used as the morphological buffer layer 110 in FIG. 4, a preset nanocrystal material may be used as the morphological buffer layer instead of the amorphous material. A nanocrystal material is a material that is entirely amorphous but partially has crystals.

  At this time, the vertical anisotropy material layer 120 may already have a vertical anisotropy when the layer is formed, but generally has a vertical anisotropy through a technique such as heat treatment after the formation of the layer. It is. In addition, the MgO layer 140 or a similar crystal structure layer is necessary on the upper portion so that the perpendicular magnetic anisotropic material layer 120 has perpendicular magnetic anisotropy.

  4, the lower layer 130 is implemented with a silicon substrate. However, the lower layer 130 may be implemented as an electrode as well as a substrate of various materials.

  As described above, by adopting an amorphous material or a nanocrystal material as a buffer for forming the perpendicular magnetic anisotropy material on the lower layer 130, the crystal structure of the lower layer 130 is simplified although the structure is simple. A buffer can be implemented regardless of its size and structure.

  At this time, it is desirable that the amorphous material and the nanocrystal material have a higher crystallization temperature than the perpendicular magnetic anisotropic material. As described above, when the crystallization temperature of the amorphous material is high, the limitation of the heat treatment temperature due to the crystallization of the buffer layer is overcome in the high temperature heat treatment process for the perpendicular magnetic anisotropy. Will be able to.

  Also, the amorphous material can be an amorphous metal, in particular FeZr. Thus, when an amorphous material is employed as the amorphous metal, electrical conduction to the perpendicular magnetic anisotropic material layer through the buffer is facilitated.

  FIG. 5 shows VSM data after heat treatment at 400 ° C. for the sample having the structure of FIG. In FIG. 5, since magnetization reversal occurs in the out-of-plane direction, it can be confirmed that perpendicular magnetic anisotropy is generated. Furthermore, various perpendicular magnetic anisotropies can be confirmed by adjusting the thicknesses of the buffer layer and the CoFeB layer. In addition, it can be confirmed that the perpendicular magnetic anisotropy is well formed using an FeZr amorphous morphological buffer layer.

  FIG. 6 is a schematic cross-sectional view of another embodiment of a magnetic element according to the present invention.

  As can be seen in FIG. 6, a perpendicular magnetic anisotropic material layer 140 may be further included between the amorphous metal layer 110 and the substrate 130. With this configuration, the texture transmission between the amorphous metal layer 110, the lower magnetic anisotropic material layer 140, and the upper perpendicular magnetic anisotropic material layer 120 is blocked, but magnetically coupled. Is possible.

  In other words, perpendicular magnetic anisotropy can be realized in the upper part regardless of the crystallized lower electrode. While the transmission of the texture of the lower and upper electrodes is blocked, the magnetic coupling is possible, and the structure of the perpendicular magnetic CoFeB / MgO is realized on the perpendicular pinning hard fixed layer (hard pinning layer) Will be able to.

  FIG. 7 is a schematic cross-sectional view of an example of a magnetic element according to the present invention including a spin valve structure. FIG. 7 illustrates a vertical-vertical spin valve structure of MgOMTJ having perpendicular magnetic anisotropy using FeZr presented in the present invention.

  In the case of the left side of FIG. 7, the antiferromagnetic material 160 is used for the lower layer, and the upper CoFeB material is operated as a pinned layer using a ferromagnetic or paramagnetic FeZr material according to the composition. In the case of the right side of FIG. 7, an L10 ordered hard pinned layer is used instead of an antiferromagnetic material as a ferromagnetic layer (Pinned layer). It was made to work.

  A CoFeB material that also has perpendicular magnetic anisotropy is operated as a free layer on the pinned layer to form (vertical pinned)-(vertical free layer), and perpendicular magnetic anisotropy is formed. A spin valve structure having the above structure can be realized, and the structure can be used to drive the magnetic storage memory.

  FIG. 8 is a schematic flowchart for performing the method of manufacturing the magnetic element of FIG. 4 of the present invention.

  In FIG. 8, an amorphous material layer is formed on the substrate (S110), and a material layer that is changed to perpendicular magnetic anisotropy is formed on the formed amorphous morphological buffer layer (S120).

  More specifically, a material that is a simple buffer layer that is not a combination of various materials or a stacked structure, but the material grown on the thin layer has vertical anisotropy even if it is thin. Even if the crystal size is different, a buffer layer that can be used in a buffer layer and does not cause a problem in a subsequent process is inserted.

  For this, a CoFeB ferromagnet material grown on top of the FeFe layer after the heat treatment using a thin FeZr layer as an amorphous buffer layer is perpendicularly anisotropic. Can be confirmed.

  This buffer layer is propagated from the body-centered cubic (bcc) structure propagated from MgO and the texture (texture; different structure such as fcc, fct, hcp, etc.) acting from below in the amorphous magnetic material CoFeB by heat treatment. Block different phases. Accordingly, it is possible to solve the problem that film formation was impossible on a material having a texture like L10 in the meantime.

  Furthermore, since magnetic coupling is possible while serving as a morphological buffer, the structure of a pinned layer / vertically anisotropic layer can be realized. Can do.

  In addition, the FeZr material used as an insertion layer can be used by searching for a desired phase because the phase change between paramagnetic and ferromagnetic materials is possible by adjusting the formation ratio of Fe and Zr. .

  The second embodiment of the present invention can be effectively used in the following cases.

-When propagating a phase through a crystallization process in a multilayer film or through a nanocrystallization process and a similar heat treatment process, the propagation on one is blocked or two or more phases collide When using a single layer amorphous material or a multilayer film combined with this to block
-When the crystallization process is used to bring about the phase transfer and the perpendicular magnetic anisotropy is developed through this, the perpendicular magnetic anisotropy is to be implemented for the purpose of eliminating the strain that the perpendicular anisotropy receives. When an amorphous metal layer having a crystallization temperature higher than the crystallization temperature of the magnetic layer or a multilayer film bonded thereto is adjacent to the magnetic layer to be used as a morphological buffer layer,
-When perpendicular magnetic anisotropy is realized on the upper part regardless of the crystallized lower electrode,
-Applying perpendicular magnetic anisotropy by allowing magnetic coupling while blocking the influence of the crystal shape of the electrodes formed on the upper and lower parts.

  In general, in the case of an existing buffer layer for perpendicular magnetic anisotropy, the lattice constant is similar due to perpendicular magnetic anisotropy, or various materials are formed as a laminated structure. It must be used to satisfy special conditions that can have perpendicular magnetic anisotropy.

  However, in this case, the thickness of the buffer layer can be increased, and a perpendicular magnetic layer is formed only when it is formed of a laminated structure of various materials or the crystal size satisfies a special condition. It can have anisotropy.

  However, according to the present invention, the perpendicular magnetic anisotropy can be confirmed in a single buffer layer having a small thickness by using an amorphous morphological buffer layer.

  In other words, since it is an amorphous material, it can be used as a buffer layer regardless of the size of the crystal. Since the crystallization temperature is high, the buffer layer can be used even at a high temperature. The perpendicular magnetic anisotropy is realized by using an amorphous buffer layer that can perform the following functions.

  Further, according to the present invention, the transmission of the texture of the lower and upper electrodes is blocked, but can be magnetically coupled, and the perpendicular magnetic CoFeB on the perpendicular pinning hard pinned layer. / MgO structure can be realized.

  FIG. 9 shows data obtained by measuring the magnitude of perpendicular magnetic anisotropy according to the thickness of CoFeB in the structure of FIG.

  As a result of measurement while changing the thickness of CoFeB from 0.5 nm to 1.6 nm, the target perpendicular magnetic anisotropy could be confirmed in the 1.6 nm section when the thickness of CoFeB was 0.7 nm. . In particular, it can be confirmed that the film has the largest vertical anisotropy at 1.1 nm.

  FIG. 10 shows data obtained by measuring the magnitude of perpendicular magnetic anisotropy according to the thickness of FeZr in the structure of FIG.

  As a result of measurement while changing the thickness of FeZr from 0.4 nm to 2.0 nm in FIG. 10, it was found that the thickness of FeZr was 0.6 nm and had the desired perpendicular magnetic anisotropy in the 2.0 nm section. Can be confirmed.

  Further, although the coercive force value of CoFeB can be changed by adjusting the thickness of FeZr, such a fact means that the coercive force can be adjusted and used in a desired range.

  The FeZr alloy exhibits various magnetic properties such as paramagnetism and ferromagnetism according to the composition of FeZr. Therefore, by adjusting the composition of Fe and Zr, it is possible to adjust the perpendicular magnetic anisotropy to a desired size, and even if the magnetic characteristics change, it has an amorphous property. It can be used in various ways.

  Although the invention has been described in terms of some preferred embodiments, the scope of the invention is not limited thereby and is intended to cover variations and modifications of the embodiments supported by the claims.

21 Amorphous metal film 110 Amorphous material layer 120 Perpendicular magnetic anisotropic material layer 130 Lower layer 140 Perpendicular magnetic anisotropic material layer 150 Fixed layer 160 Antiferromagnetic material layer

Claims (18)

A free layer that can have magnetization in a variable direction;
A fixed layer having magnetization in a fixed direction;
A tunnel insulating film formed between the free layer and the fixed layer,
The fixed layer includes a ferromagnetic film and an amorphous metal film.   The magnetic tunnel junction device according to claim 1, wherein a crystallization temperature of the amorphous metal film is higher than that of the ferromagnetic film.   2. The magnetic tunnel junction device according to claim 1, wherein a crystallization temperature of the amorphous metal film is higher than that of the ferromagnetic film and the tunnel insulating film.   The magnetic tunnel junction device according to claim 1, wherein the amorphous metal film is a magnetic material.   The magnetic tunnel junction element according to claim 1, wherein the fixed layer has a laminated structure in which the amorphous metal film is formed between the ferromagnetic films.   The magnetic tunnel junction element according to claim 1, wherein the amorphous metal film contains FeZr.   The magnetic tunnel junction element according to claim 1, wherein the magnetic tunnel junction element further includes an antiferromagnetic material layer below the fixed layer. The lower layer,
A pre-set amorphous or nanocrystal material layer formed on the lower layer;
And a perpendicular magnetic anisotropic material layer formed on the amorphous or nanocrystal material layer.   The magnetic tunnel junction device of claim 8, wherein the amorphous material and the nanocrystal material are materials having a higher crystallization temperature than the perpendicular magnetic anisotropic material.   The magnetic tunnel junction device according to claim 9, wherein the amorphous material is an amorphous metal.   The magnetic tunnel junction device according to claim 10, wherein the amorphous metal is FeZr.   The magnetic tunnel junction device according to claim 11, wherein the composition ratio of the FeZr is set in advance according to a target magnitude of perpendicular anisotropy in the perpendicular anisotropy material layer.   The magnetic tunnel junction device according to claim 11, wherein the thickness of the FeZr layer is preset according to a target vertical anisotropy in the perpendicular anisotropy material layer.   The magnetic tunnel junction device according to claim 13, wherein a thickness of the FeZr layer is 0.6 nm to 2.0 nm.   9. The magnetic tunnel junction device according to claim 8, wherein the perpendicular magnetic anisotropic material is CoFeB.   The magnetic tunnel junction device according to claim 15, wherein the CoFeB layer has a thickness of 0.7 nm to 1.6 nm.   The magnetic tunnel junction device according to claim 11, wherein the lower layer is a perpendicular magnetic anisotropic material layer.   The magnetic tunnel junction device of claim 11, wherein the lower layer includes an antiferromagnetic material layer.

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