JP2005333106A - Switched-connection element and manufacturing method therefor, and device having switched-connection element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a switched-connection element that achieves a thinner film stack, especially a thinner antiferromagnetic film, and improves a one-way anisotropy constant J<SB>k</SB>and a blocking temperature T<SB>B</SB>, and its preferable manufacturing method as well as a device equipped with the switched-connection element. <P>SOLUTION: In a switched-connection element 1 that is formed by stacking an antiferromagnetic layer 4 and a ferromagnetic layer 5 in order on a substrate 2, the ferromagnetic layer 5 that is connected to the antiferromagnetic layer by switching, the antiferromagnetic layer 4 has a regular phase (Mn<SB>3</SB>Ir) of an Mn-Ir alloy. A preferable manufacturing method for the switched-connection element is when forming an antiferromagnetic thin film layer, to heat a substrate up to a specified temperature preset so as to form the regular phase of the Mn-Ir alloy, and to apply annealing treatment to it after the antiferromagnetic thin film layer has been formed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exchange coupling element, a manufacturing method thereof, and a device including an exchange coupling element such as a spin valve magnetoresistive element, a tunnel magnetoresistive element, a magnetic head, and a magnetic memory.

  A magnetic recording medium represented by a hard disk is expected to further improve the recording density, and accordingly, a head having a magnetoresistive element is required to have higher performance. In particular, in a spin-valve magnetoresistive element that is advantageous for narrowing the read head, it is essential to reduce the thickness of a laminated film composed of adjacent ferromagnetic layers and antiferromagnetic layers.

  Therefore, it is important how to maintain the characteristics of the spin valve film in an extremely thin region. The exchange magnetic anisotropy induced at the interface of the exchange coupling element composed of a ferromagnetic layer and an antiferromagnetic layer plays a central role in fixing the magnetization of the ferromagnetic layer as the pinned layer in terms of the function of the spin valve film. However, it is an important technical issue to extract this effectively and stably under the ultrathin film.

The exchange magnetic anisotropy is evaluated by a unidirectional anisotropy constant J _k representing exchange coupling energy per unit area (so-called exchange coupling strength) at the interface between the ferromagnetic layer and the antiferromagnetic layer. This J _k is represented by the product of Ms, df, and Hex, Ms is the saturation magnetization of the ferromagnetic layer, measured by a vibrating sample magnetometer (VSM), and df is the film thickness of the ferromagnetic layer. Hex is an exchange coupling magnetic field between the antiferromagnetic layer and the ferromagnetic layer, and the shift amount from the zero magnetic field point at the center of the MH loop corresponding to the change in magnetization of the pinned layer in the magnetization curve, or the magnetic field It is defined as the amount of shift from the zero magnetic field point at the center of the MR loop that occurs with changes in the magnetization direction of the pinned layer in the resistance change curve.

In a magnetic recording device such as a hard disk drive, the internal temperature may rise to 100 ° C. or more under actual use, and the magnetoresistive element portion further rises by several tens of degrees Celsius due to self-heating by the sense current. The maximum operating temperature is about 150 ° C. For this reason, the exchange magnetic anisotropy induced in the pinned layer by the antiferromagnetic layer is reduced, and the magnetization of the pinned layer pinned in one direction is easily disturbed by the external magnetic field. This decrease in heat resistance becomes more prominent as the film thickness of the antiferromagnetic layer decreases. By the way, since the ratio of the total film thickness in the exchange coupling element is the largest in the antiferromagnetic layer, it is necessary to reduce the film thickness of the antiferromagnetic layer in order to reduce the thickness of the element. Therefore further improvement of the J _k are required.

With respect to the invention of the exchange coupling element and its manufacturing method for the purpose of improving the unidirectional anisotropy constant J _k , an application has been filed by, for example, Patent Documents 1 to 3 by the same inventors as the present invention. Non-Patent Document 1 provides a comprehensive description of the technology, including changes in technology, regarding the magnetic anisotropy of the antiferromagnetic layer and its role. For the convenience of explanation of the present invention, some of the disclosure contents of the above-mentioned various references will be described later with appropriate citation.

First, regarding the film thickness of the antiferromagnetic layer, the item “critical film thickness” in the left column of P62 of Non-Patent Document 1 includes the following description based on FIG. FIG. 20 is a diagram disclosed in Non-Patent Document 1 as FIG. 12 and shows the dependence of the unidirectional anisotropy constant (J _k ) on the antiferromagnetic layer thickness (d _AF ). .

  That is, Non-Patent Document 1 states that “the antiferromagnetic layer of the present HDD spin valve thin film is strongly required to be extremely thin. In order to induce a large exchange magnetic anisotropy with a very thin film thickness. What kind of antiferromagnetic material is suitable for this? In reviewing the history of development of antiferromagnetic materials for spin valve thin films so far, many materials have been tried since 1995-96. As a result, PtMn, which exhibits a large unidirectional anisotropy constant and a high blocking temperature, is the current standard, but the biggest problem with PtMn is that its critical film thickness is 100-200 A. In the case of PtMn, it is known that the degree of ordering by heat treatment after film formation affects the exchange magnetic anisotropy, and when ordering is completely advanced Can reduce critical film thickness to around 60-70 A Although it is shown, it is described that “it is not thin enough in any case,” and based on FIG. 20, “Mn—Ir among the antiferromagnetic materials studied so far. The critical film thickness is about half that of Mn-Ni of the same g-Mn alloy. Anisotropy plays a big role. "

As described above, Mn-Ir has the highest possibility of reducing the film thickness, but as is clear from FIG. 20, the unidirectional anisotropy constant (J _k ) is lower than that of PtMn or NiMn. There is.

By the way, as the problems required for the spin valve magnetoresistive element, there are the following problems in addition to the problem of making the antiferromagnetic film extremely thin. These problems will be described below with reference to the description in Patent Document 2. That is, “The spin-valve magnetoresistive element used as a reproducing head of a hard disk drive has reliability against disturbance magnetic field, especially operating characteristics at high temperature, ESD (Electrostatic discharge), and prevention of magnetization reversal of the fixed magnetic layer. are required to have high blocking temperature T _B and the exchange coupling magnetic field Hex. Further, the recording density requires reducing the thickness of the spin-valve type magnetoresistive element, both requests improvement of extremely thin and heat-resistant and and. especially corresponding to 40 Gbit / in ² than recording density is, the 300 ° C. or higher are needed as T _B. "
The ESD resistance is described as follows in the right column “Blocking Temperature” on page 59 of Non-Patent Document 1. That is, “In spin valve films, it is important to avoid ESD (electrostatic discharge) breakdown phenomenon, in which pinning characteristics of pinned layer magnetization deteriorate even if the device is not physically destroyed due to an instantaneous large current due to electrostatic discharge. This is understood as a phenomenon in which the exchange magnetic anisotropy of the fixed layer is changed by the action of the induced magnetic field as the temperature of the spin valve element rises due to the ESD current. The exchange magnetic anisotropy of the antiferromagnetic layered film decreases with increasing measurement temperature and disappears at a certain finite temperature (blocking temperature), so increasing the blocking temperature is one effective ESD countermeasure. . However, although the blocking temperature is sometimes matching the Neel antiferromagnetic, especially if the antiferromagnetic layer thickness (d _AF) is thin, d _AF becomes a temperature below the Neel point Decreases with decreasing. "Effect, is described.

Further, the Patent Document 2, the conventional relative "above problems have been addressed by increasing the thickness of the examination, or the antiferromagnetic layer of the antiferromagnetic layer materials. For example, T _B is 300 number The use of a Pt-Mn alloy that is too high can be mentioned, but the antiferromagnetic layer made of a Pt-Mn alloy has a problem that it is thick enough to exhibit its function as an antiferromagnetic layer. "Mn-Ir alloy is the material with the smallest critical thickness among the constituent materials of various antiferromagnetic layers. According to this Mn-Ir alloy, it depends on the manufacturing method." If the thickness is 5 nm or more, a saturation value of J _k can be obtained, and the absolute value of J _k is comparable to that of the Pt—Mn alloy, but it has been said that the T _B is as low as 250 ° C. or less. In contrast, increasing the thickness increases the magnetic anisotropy energy of the crystal grains in the antiferromagnetic layer. In, increasing the T _B can be. For example, if also the film thickness and 20nm in Mn-Ir film is T _B exceeding 300 ° C. is obtained. However, because of the narrower gap mentioned earlier, anti it is necessary to the ferromagnetic layer and 15nm or less, the improvement of T _B by the thickness increase is not a realistic means. Further, the thickness increase of the antiferromagnetic layer, a decrease in J _k, reduction of ΔR Rs increases, resulting in a decrease in magnetoresistive change rate (MR ratio), etc. For this reason, the Mn-Ir film thickness must be compromised with an appropriate value, usually 7 to 10 nm. used. Therefore, it is difficult. "effect according to the T _B and 300 ° C. or more Mn-Ir alloy.

In view of the above problems, the invention of Patent Document 2 discloses a method for modifying an antiferromagnetic layer. In other words, "has high unidirectional anisotropy constant J _k, and have a high blocking temperature T _B, in order to obtain a thin exchange coupling element thickness, forming an antiferromagnetic layer on a substrate, the “Antiferromagnetic layer is heat-treated in a vacuum atmosphere having an initial vacuum of 10 −9 Torr or less”.

Patent Document 1 states that “in order to obtain an exchange coupling element having a high unidirectional anisotropy constant J _k and maintaining various characteristics even when it is thinned, an underlayer, an antiferromagnetic layer are formed on a substrate. And a ferromagnetic layer exchange-coupled with the antiferromagnetic layer are sequentially stacked, the underlayer is made of at least two undercoat films, and any one of the undercoat films is made of a Cu film and the other Any one of them is made of a Ni—Fe alloy film or a Co—Fe alloy film ”.

Further, Patent Document 3 states that “in order to provide an exchange coupling element having a high unidirectional anisotropy constant J _k and a method for manufacturing the same, an antiferromagnetic layer is laminated on a substrate, and the antiferromagnetic layer is formed. A magnetization pinned layer whose magnetization direction is fixed by exchange coupling with the antiferromagnetic layer is laminated on at least a part or all of the magnetization pinned layer and expressed by a composition formula Co _x Fe _100-x. , Including alloys in which x indicating the composition ratio is in the range of 42 ≦ x ≦ 83 in atomic percent ”is disclosed.

Furthermore, Non-Patent Document 1 discloses the effect of the annealing treatment on the Mn—Ir film (the effect of improving J _k ) based on FIGS. 13 and 14. 18 and 19 correspond to FIGS. 13 and 14 of Non-Patent Document 1.

To cite the description of Non-Patent Document 1, “FIG. 18 shows a Mn ₇₅ Ir ₂₅ d _AF / Co ₇₀ Fe ₃₀ (40 produced on a Ta / Ni—Fe / Cu buffer layer on a Si substrate with a thermal oxide film. A) The dependence of J _{K on} the antiferromagnetic layer thickness (d _AF ) of the laminated film as a function of the heat treatment temperature (T _a ) in the magnetic field (1 kOe) after film formation. with the, but J _K Yuku increases, in the heat treatment of the above T _a = 300 ° C, with increasing T _a reversed in antiferromagnetic film thickness in the region of d _AF = 50 a or less ultrathin J _K is to Yuku "effect described decrease in Te,
Further, “According to the results of FIG. 19, it was found that J _K gradually increased with the extension of the heat treatment time except for the case of d _AF = 30 A. After the heat treatment for 200 h, d _AF A large value of J _K = 0.87 erg / cm ² was obtained in the laminated film of = 50 A or 75 A. This value is a unidirectional anisotropic reported in the PtMn / Co-Fe system in practical use. This value is more than twice the sex constant, and is considered to be attractive enough to meet the recent demands for ultra-thin antiferromagnetic layers. As a result of structural analysis by -of-plane X-ray diffraction method, it has been separately confirmed that structural changes such as increase in crystal grain size and ordering of the antiferromagnetic layer have not occurred ".

  Although the techniques described in Patent Documents 1 to 3 and Non-Patent Document 1 are effective, they are not yet sufficient for the request for the above-mentioned problems. However, the effect is a technique that is added by applying the present invention to the present invention described later.

  Next, a device provided with an exchange coupling element such as a tunnel type magnetoresistive element and a magnetic memory other than the spin valve type magnetoresistive element used in the magnetic head will be described.

Recently, there is an increasing demand for so-called non-volatile memories that store data even when the power is turned off, and magnetic memories (MRAM) have been proposed as one type of non-volatile memories. In this magnetic memory, use of a tunneling magnetoresistive (TMR) element as a storage element is being studied. The tunnel type magnetoresistive element has a laminated structure of an antiferromagnetic layer / magnetization fixed layer / insulating layer / magnetization free layer. This tunnel type magnetoresistive element also has a configuration of an antiferromagnetic layer / magnetization fixed layer. The above-described exchange coupling element is provided. If the unidirectional anisotropy constant J _k of the exchange coupling element is small, the magnetization direction of the magnetization fixed layer is likely to fluctuate due to an external magnetic field or the like, and the recorded information held in the recording element (tunnel magnetoresistive element) is lost. since there is a possibility that cracking, in order to improve the reliability of magnetic memories, improvement in unidirectional anisotropy constant J _k in exchange coupling elements are required.
JP 2000-171012 A JP 2002-198585 A JP 2002-289947 A Tsunoda et al., “Exchange magnetic anisotropy of ferromagnetic / antiferromagnetic multilayers: Magnetic anisotropy and role of antiferromagnetic layers”, Journal of Japan Society of Applied Magnetics, Vol.28, No.2,2004, P55 to P65

As described above, in the device provided with the exchange coupling elements as well as exchange coupling elements, to have high unidirectional anisotropy constant J _k, to have a high blocking temperature T _B, the film thickness is thin, the ESD resistance Is required. According to Non-Patent Document 1, the unidirectional anisotropy constant J _k is considerably improved with respect to an exchange coupling element using an Mn—Ir alloy as an antiferromagnetic film due to the demand for thinning the film. to meet the demand for thinning of the magnetic layer, the further improvement of the J _k is desired, also for resistance to ESD improvements (achievement of 300 ° C. or higher) further improvement of the blocking temperature T _B is required.

Furthermore, the large J _k improvement effect disclosed in Non-Patent Document 1 can be achieved by annealing for a long time (several tens to 200 hours), and reduction of manufacturing time and manufacturing cost is desired.

The present invention has been made in view of the above, an object of the present invention, improvement in the laminated film, particularly thinning of the antiferromagnetic film, improvement in unidirectional anisotropy constant J _k and blocking temperature T _B It is another object of the present invention to provide an exchange coupling element, a suitable manufacturing method thereof, and a device including the exchange coupling element.

The above-mentioned subject is achieved by the following. That is, in an exchange coupling element in which an antiferromagnetic layer and a ferromagnetic layer exchange-coupled to the antiferromagnetic layer are sequentially stacked on a substrate, the antiferromagnetic layer is formed of an ordered phase of an Mn—Ir alloy ( Mn ₃ Ir) (Claim 1). The ordered phase in claim 1 includes a part in which a part of Ir is replaced with a third element such as Ru.

  As an embodiment of the invention of claim 1, the inventions of claims 2 to 4 are preferable. That is, in the exchange coupling device according to claim 1, the Mn—Ir alloy has an Ir composition ratio of 20 to 33 atomic% (claim 2).

  Furthermore, in the exchange coupling element according to claim 1 or 2, the average in-plane crystal grain size of the Mn-Ir alloy in the antiferromagnetic layer is 9 nm (90%) or more. 3).

  In the exchange coupling element according to claim 1, an underlayer is provided between the base and the antiferromagnetic layer (claim 4).

According to the invention of the exchange coupling elements will be described in detail later, the presence of ordered phase (Mn ₃ Ir), improved blocking temperature T _B, the 360 ° C. or higher. In addition, the unidirectional anisotropy constant J _k is remarkably improved as compared with the conventional one, and a maximum value of 1.3 erg / cm ² is obtained at the maximum, thereby enabling the film to be extremely thinned. Further, the good characteristics can be obtained in a short annealing time (for example, about 1 hour).

  Next, as a method for manufacturing the exchange coupling element of the present invention, the inventions of the following claims 5 to 7 are preferable. That is, an exchange coupling element in which an antiferromagnetic thin film layer made of an Mn—Ir alloy and a ferromagnetic thin film layer exchange-coupled to the antiferromagnetic thin film layer are sequentially formed on a substrate with or without an underlayer. In the manufacturing method, when the antiferromagnetic thin film layer is formed, the substrate is heated to a predetermined substrate temperature that is predetermined in order to form an ordered phase of the Mn—Ir alloy, and the antiferromagnetic thin film layer is heated. Annealing treatment is performed after the formation of the ferromagnetic thin film layer (claim 5).

  The predetermined substrate temperature when forming the antiferromagnetic thin film layer on the substrate via the underlayer is at least 100 ° C. or more when the underlayer material is Ru, and 100 when the underlayer material is Cu. It is set to -180 degreeC (Claim 6).

  Furthermore, the heat treatment temperature of the antiferromagnetic layer thin film during the annealing treatment is 280 to 360 ° C. (Claim 7).

  Details of the effects of the fifth to seventh aspects will be described later.

  In addition, as the invention of a device comprising any of the exchange coupling elements described above, the inventions of the following claims 8 to 11 are preferable. That is, a spin valve magnetoresistive element comprising the exchange coupling element according to any one of claims 1 to 4 (claim 8). Furthermore, the tunnel type magnetoresistive element (Claim 9) characterized by comprising the exchange coupling element of any one of Claims 1 thru | or 4. Furthermore, a magnetic head comprising the exchange coupling element according to any one of claims 1 to 4 (claim 10). A magnetic memory comprising the tunnel magnetoresistive element according to claim 9 (claim 11).

According to the present invention, thin, unidirectional anisotropy constant J _k improved and blocking temperature T the preferred manufacturing method as well as good properties as exchange coupling elements with improved _B of the multilayer film particularly antiferromagnetic film A device having an exchange coupling element having the following can be provided.

Next, embodiments of the present invention will be described with reference to the drawings. In the following description, the pressure is expressed in units of Torr. However, when this is converted into Pa (Pascal) which is an SI unit, it may be converted by 1 Torr = 133 Pa. In some cases, the film thickness is expressed in units of Å, but when this is converted into nm (nanometer), which is an SI unit, conversion may be made by 1 Å = 0.1 nm. Further, the magnetic field may be expressed in units of Oe (Oersted), but when this is converted to A / m (ampere per meter), which is an SI unit, it may be converted by 1 Oe = 79.58 A / m. .
(First embodiment: exchange coupling element)
HYPERLINK "http://www.patent.ne.jp/patent/cache/" \ l "fig1" FIG. 1 is a schematic cross-sectional view of an embodiment of a typical exchange coupling element according to the present invention. In FIG. 1, the exchange coupling element 1 includes an antiferromagnetic layer 4 laminated on a substrate 2, a ferromagnetic layer 5 formed on the antiferromagnetic layer 4, and a protective layer 6. The substrate 2 preferably has, for example, at least a surface provided with a layer made of Ta of about 0.5 to 10 nm. The substrate 2 may be formed by forming a layer made of a Ta—Ni—Fe alloy on the surface in place of the layer made of Ta.

The antiferromagnetic layer 4 is a layer made of an Mn—Ir alloy having a film thickness of 4 nm to 19 nm, for example, and exchange-couples with the ferromagnetic layer 5 to fix the magnetization of the ferromagnetic layer 5 in one direction. As the Mn—Ir alloy, it is preferable to use an Mn—Ir film having an Ir composition ratio of 20 atomic% to 30 atomic%, particularly a composition classified as Mn ₇₅ Ir ₂₅ .

The ferromagnetic layer 5 is a layer made of, for example, a Ni—Fe alloy or Co—Fe alloy having a film thickness of 1 to 5 nm, or Co, or a laminated film thereof. In particular, the composition ratio of Fe is 5 atom% or more and 50 atoms. % Or less Co-Fe alloy is preferred. In addition, other additive elements may be added to both the Ni—Fe alloy and the Co—Fe alloy. Further, the ferromagnetic layer 5 may have a laminated ferrimagnetic structure by laminating two ferromagnetic films via a Ru film having an appropriate thickness. According to the laminated ferrimagnetic structure, the magnetization direction of the ferromagnetic layer is fixed by antiferromagnetic coupling acting between the two ferromagnetic films, maintaining a large magnetic anisotropy be heated to a blocking temperature T _B It becomes possible to do. The protective layer 6 is a layer made of Ta having a film thickness of 0.5 to 5 nm, for example, and prevents oxidation of the surface of the ferromagnetic layer 5.

  Further, an underlayer may be provided between the substrate 2 and the antiferromagnetic layer 4. The base layer may be either a single base film or a laminated structure of two or more base films. In the case of a single base film, it is preferably a Cu film, a Ni—Fe alloy film, or a Co—Fe alloy film. In this case, the thickness of the underlayer is preferably in the range of 1 nm to 5 nm. In the case of a layered base layer, one of the two base films is a Cu film and the other is a Ni-Fe alloy film or a Co-Fe alloy film, particularly a Ni-Fe-Cr alloy. A film is preferred. In this case, the total thickness of the base layer is preferably in the range of 1 nm to 5 nm, and the thickness of each base film is preferably 0.5 nm to 1.5 nm.

  If the total thickness of the underlayer is 1 nm or more, it becomes possible to maintain the (111) -oriented crystallinity of the underlayer, and if the layer thickness is 5 nm or less, the exchange coupling element 1 is made to have magnetoresistance effect. When used in an element or the like, the shunt current can be reduced by suppressing the shunting of the detection current. Furthermore, when the underlayer has a laminated structure, the crystallinity of each underlayer can be maintained if the thickness of each underlayer is 0.5 nm or more, and each thickness is 1.5 nm or less. Then, it becomes possible to reduce the detected current santros in the same manner as described above.

  Cu, Ni—Fe alloy, and Co—Fe alloy constituting the underlayer are all materials having an fcc crystal structure (face-centered cubic structure), and these materials preferentially orient the (111) plane by sputtering or the like. Since the film is formed, the exposure probability of the (111) plane on the film surface is increased. Therefore, when the antiferromagnetic layer 4 and the ferromagnetic layer 5 are epitaxially grown on the underlayer, the antiferromagnetic layer 4 and the ferromagnetic layer 5 are formed in a (111) plane orientation. As a result, The unidirectional anisotropy constant Jk induced at the interface between the antiferromagnetic layer 4 and the ferromagnetic layer 5 can be increased, and the exchange coupling magnetic field Hex can be improved.

  As described above, the exchange coupling element has various configurations, and a configuration according to the purpose is adopted. Therefore, the configuration of the exchange coupling element according to the present invention is not limited to the above configuration.

Second Embodiment: Method for Manufacturing Exchange Coupling Element
FIG. 2 is a schematic plan view of a film forming apparatus suitable for use in manufacturing the exchange coupling element of the present invention. The film forming apparatus 21 is mainly composed of a metal film forming chamber 22, a sputtered film forming chamber 23, a heat treatment chamber 24, a transfer chamber 25, a gas flow rate control unit 26, and a vacuum gauge 27. The metal film formation chamber 22 is connected to the transfer chamber 25 via a gate valve 22a, the sputter film formation chamber 23 is connected to the transfer chamber 25 via a gate valve 23a, and the heat treatment chamber 24 is further connected via a gate valve 24a. It is connected to the transfer chamber 25.

  The transfer chamber 25 is provided with three sets of transfer loaders 28, 29, and 30. These transfer loaders 28, 29, and 30 transfer a film formation object stored in the transfer chamber 25 to a metal film forming chamber. 22, it can be transferred to the sputtered film formation chamber 23 and the heat treatment chamber 24, respectively. In addition, a gas flow rate control unit 26 and a vacuum gauge 27 are connected to the metal film forming chamber 22, the sputtered film forming chamber 23, and the heat treatment chamber 24, respectively, so that the pressure in each chamber and the type of atmospheric gas can be adjusted. It has become.

  The metal film forming chamber 22 is provided with a plurality of film forming targets 22b... And a sample stage 22c for moving the film forming object transferred from the transfer chamber 25. The targets 22b are attached to the inside of the ceiling of the metal film forming chamber 22, and the sample stage 22c is movably attached to the floor surface of the metal film forming chamber 22. Each target is made of, for example, high-purity Ta, Cu, Ni—Fe—Cr alloy, Co—Fe alloy, and Mn—Ir alloy.

Next, a method for manufacturing the exchange coupling element 1 will be described. First, the substrate 2 made of Si is placed in the transfer chamber, and the substrate 2 is transferred to the heat treatment chamber 24 by the transfer loader 30. In the heat treatment chamber 24, for example, a SiO ₂ film which is a part of the base layer 3 is formed on the surface of the substrate 2 by performing heat treatment in an oxygen atmosphere. Next, the substrate 2 is returned to the transfer chamber 25 by the transfer loader 30.

The inside of the metal film forming chamber 22 is previously depressurized to an initial pressure of 10 ⁻⁹ Torr or less, preferably 10 ⁻¹⁰ Torr or less by an exhaust pump (not shown). The gate valve 22a is released after the inside of the transfer chamber 25 is almost the same as or slightly lower than the inside of the metal forming chamber 22, and the substrate 2 is moved to the sample stage 22c of the metal film forming chamber 22 by the transfer loader 28. Transport. Next, high purity argon gas is introduced, the pressure in the metal film forming chamber 22 is set to 0.6 to 3 mTorr, and the temperature of the base 2 is kept at room temperature, and the sample stage 22c is driven to set the base 2 to the Ta target. Move down 22b. Then, using a DC magnetron sputtering method, for example, a Ni—Fe—Cr film as a part of the underlayer 3 is formed on the previously formed SiO ₂ film while applying a magnetic field in one direction. Next, a Cu film is sequentially formed by the same method as the formation of the Ni—Fe—Cr film to form the underlayer 3.

Next, the antiferromagnetic layer 4 is formed on the underlayer 3. The film thickness of the antiferromagnetic layer 4 is preferably in the range of 4 nm or more and 19 nm or less, and this film thickness is adjusted by controlling the film formation time while keeping the film formation speed constant. The composition of the antiferromagnetic layer 4 can be adjusted to a composition of Mn _y Ir _{100 -y} (composition ratio y is in the range of 70 ≦ y ≦ 80 in atomic%) by adjusting the alloy composition of the target. When the antiferromagnetic layer 4 is formed, as described above, the substrate temperature is preferably 100 to 180 so that the predetermined substrate temperature is predetermined in order to form the ordered phase of the Mn—Ir alloy. Heat to ℃.

Next, the ferromagnetic layer 5 is formed by the same method as the formation of the underlayer 3 and the antiferromagnetic layer 4. The ferromagnetic layer 5 has a composition of Co _x Fe _100-x ( _x indicating the composition ratio is preferably in the range of 42 ≦ x ≦ 83 in atomic%. The film thickness of the ferromagnetic layer 5 is antiferromagnetic. As in the case of the layer 4, the film formation rate is fixed and the film formation time is controlled.

  Further, a reaction preventing layer made of Cu and a protective layer made of Ta are sequentially laminated on the ferromagnetic layer 5.

Next, the substrate 2 on which the layers 3, 4... Are stacked is transferred to the heat treatment chamber 24 via the transfer chamber 25 using the transfer loaders 28 and 30, and the initial pressure in the heat treatment chamber 24 is 10 ⁻⁹ Torr or less. Heat treatment (annealing) is preferably performed in a state where the pressure is reduced to 10 ⁻¹⁰ Torr or less. As described above, the heat treatment temperature is preferably 280 to 360 ° C., and the heat treatment time is about 1 hour. 2 is heated by a heater built in the heat treatment chamber 24 or infrared rays (IR) described later. By this heat treatment, an exchange coupling magnetic field appears at the interface between the antiferromagnetic layer 4 and the ferromagnetic layer 5, and the magnetization direction of the ferromagnetic layer 5 is fixed in one direction. In this way, the exchange coupling element 1 described in the first embodiment is obtained.

  In the heat treatment, after a protective layer made of Ta is formed, the film is transferred from the metal film forming chamber 22 to the transfer chamber 25, and then the substrate 2 on which the layers 3, 4,. Thus, heat treatment in a magnetic field may be performed in a vacuum atmosphere. The degree of vacuum, magnetic field strength, and heat treatment conditions at that time are the same as the conditions in the heat treatment chamber 24, and are therefore omitted.

In the method for manufacturing the exchange coupling element 1, a separate heat treatment may be performed immediately after the formation of the antiferromagnetic layer 4 and before the formation of the ferromagnetic layer 5. After the formation of the antiferromagnetic layer 4 and before the formation of the ferromagnetic layer 5, it is transferred to the heat treatment chamber 24 while maintaining the vacuum atmosphere, and then transferred again to the metal formation chamber 22. A reaction preventing layer and a protective layer are formed. By performing this heat treatment, the J _k of the exchange coupling element 1 can be further increased. The heat treatment in this case is not limited to heat treatment by heater heating, but may be heat treatment by infrared light irradiation.

The heat treatment by the infrared light irradiation is performed by an infrared heat treatment apparatus 40 as shown in FIG. The infrared heat treatment apparatus 40 includes a chamber 42 having a transmission window 41 that transmits infrared light, an exhaust mechanism (not shown) that makes the inside of the chamber 52 a vacuum atmosphere of 10 ⁻⁹ Torr or less, preferably 10 ⁻¹⁰ Torr or less. The infrared light source 43 is mainly configured to transmit infrared light from the outside of the chamber 42 to the transmission window 41 and irradiate the chamber 42 with the infrared light.

The chamber 42 is connected to an exhaust mechanism (not shown) so that the inside of the chamber 42 can be in a vacuum atmosphere of 10 ⁻⁹ Torr or less, preferably 10 ⁻¹⁰ Torr or less. A sample stage 44 is provided in the chamber 42 so that the substrate 2 can be fixed via a sample holder 45. A temperature sensor 46 such as a thermocouple is attached to the sample stage 44. Further, the sample stage 44 is configured to be driven in the vertical direction in FIG. 3 and is configured to be able to adjust the irradiation distance between the infrared light source 43 and the substrate 2.

A transmission window 41 that transmits infrared light is provided in the upper portion of the chamber 42. The transmission window 41 is preferably made of a material having a high transmittance with respect to infrared light and having an excellent gas barrier property in order to keep the inside of the chamber 42 at a high vacuum, such as α-Al ₂ O _3. .

  The infrared light source 43 includes a filament 48 connected to a power supply 47 and a reflector 49 having an opening 60. Infrared light emitted by energizing the filament 48 from the power supply 47 is once condensed at a focal point located in the infrared light source 43 by the condensing effect of the reflection plate 49, and is transmitted from the opening 60 to the transmission window 41 of the chamber 42. Radiated radially toward Further, the infrared light is configured to pass through the transmission window 41 and reach the vicinity of the sample stage in the chamber 42.

  Note that a diaphragm (not shown) is attached to the opening 60 so that the irradiation range of infrared light can be adjusted. Similarly to the sample stage 44, the infrared light source 43 is configured so that it can be driven in the vertical direction in FIG. 3 so that the irradiation distance from the substrate 2 can be adjusted.

The heat treatment temperature of the antiferromagnetic layer 4 at the time of infrared light irradiation is adjusted by, for example, the amount of current supplied to the infrared light source. The initial pressure at the time of infrared light irradiation is 10 ⁻⁹ Torr or less, preferably 10 ⁻¹⁰ Torr or less. When the initial pressure falls below 10 ⁻⁹ Torr, oxygen, water, etc. remaining in the atmosphere are adsorbed on the surface of the antiferromagnetic layer 4, and in some cases, the surface of the antiferromagnetic layer 4 is oxidized or altered. , _Jk is lowered, which is not preferable. Thus, by heat-treating the antiferromagnetic layer 4 in the high vacuum described above, the oxidation of the surface of the antiferromagnetic layer 4 and the adsorption of gas atoms to the surface can be prevented. The surface state of the antiferromagnetic layer 4 can be improved by changing the magnetic field, and if a ferromagnetic layer 5 is laminated on this surface, an exchange coupling magnetic field is developed between the antiferromagnetic layer 4 and the ferromagnetic layer 5. And high J _k can be expressed.

(Third Embodiment: Spin Valve Magnetoresistive Element)
FIG. 4 is a schematic cross-sectional view of a spin valve magnetoresistive element equipped with an exchange coupling element. In FIG. 4, a spin valve magnetoresistive element 10 includes an exchange coupling element 11 according to the present invention laminated on a substrate 12, a nonmagnetic high conductor layer 16 formed on the exchange coupling element 11, and a nonmagnetic layer. It is composed of another ferromagnetic layer 17 formed on the high conductor layer 16 and a protective layer 18.

  The exchange coupling element 11 is the same as the exchange coupling element 1 described in the first embodiment, and an underlayer 13 stacked on a substrate 12 and an antiferromagnetic material formed on the underlayer 13. The layer 14 includes a ferromagnetic layer 15 formed on the antiferromagnetic layer 14. The underlayer 13 is a laminated film composed of a first underlayer 13 a adjacent to the substrate 12 and a second underlayer 13 b adjacent to the antiferromagnetic layer 14. The exchange coupling element 11, the substrate 12, the underlayer 13 (the first underlayer film 13 a and the second underlayer film 13 b), the antiferromagnetic layer 14, and the ferromagnetic layer 15 are exchange coupled as described in the first embodiment. Since the configuration, material, film thickness, etc. of the element 1, the substrate 2, the base layer 3 (the first base film 3a and the second base film 3b), the antiferromagnetic layer 4 and the ferromagnetic layer 5 are the same, the description thereof will be given. Omitted.

(Fourth Embodiment: Tunnel Type Magnetoresistive Element)
FIG. 5 is a schematic cross-sectional view of a tunnel type magnetoresistive element. The tunnel type magnetoresistive element 50 includes an underlayer 3, an antiferromagnetic layer 4, a ferromagnetic layer 5, an insulating layer 56, another ferromagnetic layer 57, and a protective layer 58 on the substrate 2 in order. It is configured by stacking. In the tunnel type magnetoresistive element 50, the stacked body of the antiferromagnetic layer 4 and the ferromagnetic layer 5 constitutes an exchange coupling element 51. The detailed configurations of the substrate 2, the underlayer 3, the antiferromagnetic layer 4, and the ferromagnetic layer 5 are the same as those of the substrate 2, the antiferromagnetic layer 4 and the ferromagnetic layer 5 described in the first embodiment. The configuration, material, film thickness, and the like are the same, and the description thereof is omitted.

The insulating layer 56 is a layer made of a nonmagnetic insulator such as Al ₂ O ₃ having a film thickness of 0.5 to 3.0 nm, for example, and is located between the ferromagnetic layer 5 and another ferromagnetic layer 47. A tunnel current depending on the magnetization direction of these layers 5 and 47 is passed. The ferromagnetic layer 57 is a layer made of, for example, a Ni—Fe alloy, a Co—Fe alloy, Co, or a laminated film thereof having a thickness of 1 to 5 nm, and is adjacent to the insulating layer 56. In the tunneling magnetoresistive element 50, the ferromagnetic layer 57 constitutes a magnetization free layer. The ferromagnetic layer 57 has a two-layer structure including a lower ferromagnetic layer 57a and an upper ferromagnetic layer 57b.

The lower ferromagnetic layer 57a is made of, for example, a composition of Co ₇₅ Fe _25. If the lower ferromagnetic layer 57a is disposed adjacent to the insulating layer 56, the TMR effect is increased. Further, the upper ferromagnetic layer 57b is, for example, a Ni—Fe alloy film. By laminating the upper ferromagnetic layer 57b, the magnetization reversal of the ferromagnetic layer 57 is facilitated, and operation in a low magnetic field is possible. The lower ferromagnetic layer 57b can have a thickness of 2 to 5 nm, for example, and the upper ferromagnetic layer 57a can have a thickness of 10 to 50 nm, for example. The protective film 58 is a film made of Ta having a thickness of 2 nm, for example. Further, a Cu layer may be disposed above the ferromagnetic layer 57 and below the protective layer 58. As a result, the sheet resistance of the upper electrode layer above the insulating layer can be reduced, which is effective for stable operation of the TMR element. The purpose of the Cu layer is to lower the electrical resistance, and Al, alloys thereof, and other low resistance materials may be used in addition to Cu.

  When an external magnetic field is applied to the ferromagnetic layer 57 which is a magnetization free layer of the tunnel type magnetoresistive element 50, the magnetization direction fluctuates due to the influence of the external magnetic field, and the magnetization direction fluctuates with the ferromagnetic layer 5. As a result, the amount of tunneling current flowing between the ferromagnetic layer 5 and the magnetization free layer 57 via the insulating layer 57 varies, thereby causing a resistance change of the tunneling magnetoresistive element 50. Since the magnetization direction of the ferromagnetic layer 5 is firmly fixed by exchange coupling with the antiferromagnetic layer 4, the magnetization direction does not change even when an external magnetic field is applied.

According to the tunneling magnetoresistive element 50 described above, since the exchange coupling element 51 according to the present invention having a high J _k is provided, the magnetization direction of the ferromagnetic layer 5 is not changed by an external magnetic field, and the high magnetoresistance The rate of change (MR ratio) can be expressed.

  Further, according to the tunnel type magnetoresistive element 50 described above, the thickness of the antiferromagnetic layer 4 can be reduced to 19 nm or less. Therefore, the total thickness of the tunnel type magnetoresistive element 50 can be reduced, and the tunnel type magnetoresistive element 50 can be reduced. The integration degree of 50 can be improved.

  Further, the ferromagnetic layer 5 of the tunnel type magnetoresistive element 50 may be a laminated ferrimagnetic layer made of a laminated body of a ferromagnetic layer and a nonmagnetic layer. With the tunnel magnetoresistive element including the ferromagnetic layer 5 made of such a laminated ferrimagnetic layer, the magnetization direction of the ferromagnetic layer 5 as the magnetization fixed layer can be more firmly fixed, and the influence of the external magnetic field can be reduced. This can be eliminated and the MR ratio can be further increased.

Note that the TMR read head may be configured by replacing the tunnel magnetoresistive element 50 with a spin valve magnetoresistive element 800 shown in FIG. According to this TMR reproducing head, since the exchange coupling element according to the present invention having a high J _k is provided, the magnetization direction of the magnetization fixed layer does not fluctuate due to an external magnetic field such as a recording magnetic field, and a high magnetoresistance change rate (MR ratio) can be expressed.

(Fifth embodiment: magnetic head)
FIG. 6 shows a GMR reproducing head according to a fifth embodiment of the present invention and a recording / reproducing separated type magnetic head in which this reproducing head is combined with an inductive recording head, and FIG. 7 shows the GMR reproducing head. The main part is shown. 6 and 7, reference numeral 800 denotes a spin valve type magnetoresistive element according to the present invention, 801 denotes an exchange coupling element according to the present invention, 803 denotes an underlayer, 804 denotes an antiferromagnetic layer, and 805 functions as a fixed magnetization layer. , 806 is a nonmagnetic conductive layer, 807 is a ferromagnetic layer functioning as a magnetization free layer, 808 is an MR electrode, 809 is a hard film, 811 is a GMR reproducing head, 812 is a lower magnetic pole (824) ) Also serves as an upper shield layer of the GMR reproducing head 811, 813 and 814 are nonmagnetic insulating films, 815 is a lower shield of the GMR reproducing head 811, 821 is a recording head, 822 is an upper pole of the recording head 821, and 823 is conductive. The body coil 824 is the lower magnetic pole of the recording head that also serves as the upper shield (812) of the GMR reproducing head 811.

  The detailed configuration of the underlayer 803, the antiferromagnetic layer 804, the ferromagnetic layer (magnetization fixed layer) 805, the nonmagnetic conductive layer 806, and the ferromagnetic layer (magnetization free layer) 807 of the spin valve magnetoresistive element 800 is as follows. The configuration of the spin valve magnetoresistive element 10 described in the third embodiment is almost the same.

  A portion where the spin valve magnetoresistive element 800 including the exchange coupling element 801 according to the present invention is sandwiched between the upper shield layer 812 and the lower shield layer 815 functions as a reproducing head, and the coil 823 made of thin film Cu is used as the upper magnetic pole 822 and the lower part. A portion sandwiched between the magnetic poles 824 functions as a recording head. In this separated recording / reproducing magnetic head, the upper shield layer 812 of the GMR reproducing head 811 is configured to also serve as the lower magnetic pole 824 of the recording head 821, but different materials are used for the upper shield layer and the lower magnetic pole. Even if it makes another structure, or arrange | positions another structure between both, the effect | action and effect of this invention are not lost.

According to the GMR reproducing head 811, since the exchange coupling element 801 according to the present invention having a high J _k is provided, the magnetization direction of the magnetization fixed layer 805 is not changed by an external magnetic field such as a recording magnetic field, and is high. Magnetoresistance change rate (MR ratio) can be expressed.

(Sixth embodiment: magnetic memory)
Next, a magnetic memory according to a sixth embodiment of the present invention will be described with reference to FIG.

 HYPERLINK "http://www.patent.ne.jp/patent/cache/" \ l "fig8" FIG. 8 is a cross-sectional view of a memory cell as a main part of the magnetic memory. This memory cell includes a MOSFET 901 which is an element for cell selection, a word line 902, a bit line 903, and a tunnel type magnetoresistive element 904. The word line 902 is connected to the MOSFET 901. The bit line 903 is connected to the tunnel type magnetoresistive element 904, and the tunnel type magnetoresistive element 904 is further connected to the MOSFET 901 through the connection wiring 905. At the time of reading data, a memory cell is selected by the MOSFET 901 and a current is passed from the word line 902 to the tunnel type magnetoresistive element 904 through the MOSFET 901.

  The recorded data can be read using the fact that the electric resistance differs depending on the magnetization directions of the magnetization fixed layer and the ferromagnetic layer of the tunnel type magnetoresistive element 904. Further, at the time of writing, a current is passed through the bit line 903 and the word line 902, and a tunnel type magnetoresistive is generated by a combined magnetic field of a magnetic field formed by a current flowing through the bit line 903 and a magnetic field formed by a current flowing through the word line 902. Only the ferromagnetic layer of the element is reversed. Since the magnetization pinned layer pinned by the antiferromagnetic layer does not reverse the magnetization but can only reverse the magnetization of the ferromagnetic layer, it can be formed with the intention of the above parallel and antiparallel states. Thereby, memory can be stored and erased.

  According to such a magnetic memory, since the tunnel type magnetoresistive element composed of the exchange coupling element is provided, the magnetization of the magnetization fixed layer is not reversed by the synthetic magnetic field, and a highly reliable memory is configured. be able to.

  Hereinafter, the results of experiments relating to structural analysis (X-ray diffraction) and various magnetic properties related to the examples of the present invention will be described in more detail.

(Configuration and manufacturing method of exchange coupling element in embodiment)
FIG. 9 shows a schematic cross-sectional view of the configuration of the exchange coupling element in the example. An underlayer composed of a 5 nm (50 mm) Ni—Fe—Cr alloy and 500 μm Cu is provided on a Si substrate having a SiO ₂ film formed on the surface by thermal oxidation, and Mn—Ir (Mn ₇₃ Ir ₂₇ ) A 100 反 antiferromagnetic layer made of an alloy and a 40 Å ferromagnetic layer made of a Co ₇₀ Fe ₃₀ alloy were sequentially laminated thereon.

The manufacturing method of the exchange coupling element is basically the above-described manufacturing method, but the film formation of the antiferromagnetic layer is performed by crystal grains by cleaning the surface of the antiferromagnetic layer and reducing impurities in the antiferromagnetic layer. In order to obtain growth and high crystal orientation, it was carried out by ultra high vacuum process (XC-process). That is, after the initial vacuum in the film forming apparatus was reduced to 3 × 10 ⁻¹¹ Torr or less, high purity argon gas having a purity of 9 nines was introduced, and the magnetron sputtering method was used. The film formation was performed while applying a magnetic field of about 30 Oe parallel to the film surface.

  Further, when the antiferromagnetic layer was formed, as described later, the temperature of the substrate to be formed was variously changed to experiment on the influence of the substrate temperature on the magnetic characteristics. Furthermore, various changes were also made regarding the heating temperature of the annealing treatment after film formation, and the effect of the heating temperature on the magnetic characteristics was tested.

(X-ray diffraction profile)
Next, the measurement result of the X-ray diffraction profile of the exchange coupling element in the above embodiment will be described. FIG. 10 shows an example of the measurement result of the X-ray diffraction profile. The horizontal axis in FIG. 10 indicates the diffraction angle (2θχ), and the vertical axis indicates the intensity. The temperatures 170 ° C., 130 ° C. and room temperature (RT) shown on the right side of the figure indicate the substrate temperature (T _sub ) when forming the antiferromagnetic layer.

As is apparent from FIG. 10, X-ray diffraction peaks (Mn ₃ Ir (110) s, Mn ₃ Ir (211) s in the figure are added) in the vicinity of 2θχ = 34 deg and 60 deg due to Mn ₃ Ir of the regular phase. Peak) is observed. Conventionally, this peak has not been observed from the ferromagnetic / antiferromagnetic laminated film, and the presence of this ordered phase in the present invention is an improvement in the magnetic characteristics described later, that is, an improvement in the unidirectional anisotropy constant J _k and blocking. It believed that resulted in improvement of the temperature T _B.

The presence of ordered phase, to improve the blocking temperature T _B can be readily understood from the known fact that "higher than the Neel temperature is disordered phase when the ordered phase." FIG. 11 is a well-known data showing the correlation between the atomic% of Ir in Mn-Ir (horizontal axis) and the Neel temperature T _N (° C.) (vertical axis), ordered and disordered phases. Is plotted for each. According to FIG. 11, when the atomic% of Ir is 25%, the Neel temperature of the disordered phase is about 450 ° C., whereas that of the ordered phase is about 650 ° C. As described in Non-Patent Document 1, that is, “the blocking temperature may coincide with the antiferromagnetic nail point, but particularly when the antiferromagnetic layer thickness (d _AF ) is thin, the temperature becomes the nail point or lower. _As is clear from the description of “decreasing with decreasing _AF ”, the highest value that the blocking temperature can reach is the Neel temperature, and it can be estimated that the blocking temperature also increases if at least the Neel temperature is high.

In the X-ray diffraction profile of FIG. 10, the peak of 2θχ = 70 deg is not a peak unique to the regular phase, but is a diffraction caused by both the irregular phase (Mn ₇₅ Ir ₂₅ ) and the regular phase (Mn ₃ Ir). It is a peak. As for the improvement and unidirectional anisotropy constant J _k specific data to improve the results of the blocking temperature T _B, described below.

(Correlation between in-plane crystal grain size of antiferromagnetic layer and substrate temperature)
In general, the average surface crystal grain size is increased, the unidirectional anisotropy constant J _k is known to be improved. FIG. 12 shows an example of the measurement result of the average in-plane crystal grain size according to the example. The horizontal axis in FIG. 12 represents the substrate temperature (T _sub ) when the antiferromagnetic layer is formed, and the vertical axis represents the average in-plane crystal grain size D ₂₂₀ (Å). For example, when the substrate temperature (T _sub ) is 100 ° C., the average in-plane crystal grain size is about 90 (Å), and the average in-plane crystal grain size increases as the substrate temperature (T _sub ) increases.

(Dependence of unidirectional anisotropy constant J _k on substrate temperature (T _sub ))
The substrate temperature dependence of the unidirectional anisotropy constant will be described with reference to FIGS. First, FIG. 13 shows an experimental result (in the case of the base layer Cu) on the substrate temperature (Tsub) dependence of the unidirectional anisotropy constant Jk performed on the exchange coupling element shown in FIG. The vertical axis in FIG. 13 represents the respective unidirectional anisotropy constants J _k (erg / cm) when the annealing heating temperature (T _a ) is 320 ° C., 280 ° C., 250 ° C. and immediately after deposition without heating (As deposited). ² ), and the horizontal axis shows the substrate temperature (T _sub ) (° C). The annealing heating was sequentially and cumulatively performed on the same sample in the order of 250 ° C., 280 ° C., and 320 ° C. The annealing time at each temperature is 1 hour.

As is apparent from FIG. 13, for example, when the substrate temperature (T _sub ) is 170 ° C. and the annealing heating temperature (T _a ) is 320 ° C., the unidirectional anisotropy constant J _k (erg / The value of cm ² ) shows a maximum value of about 1.3.

According to FIG. 13, in order to obtain a good unidirectional anisotropy constant J _k (erg / cm ² ), a preferable temperature range of the substrate temperature (T _sub ) is 100 to 180 ° C. Further, the difference from the prior art described in Non-Patent Document 1 is that even if the heating time in the annealing treatment is short, a high Jk higher than the conventional maximum value is obtained.

Next, FIG. 14 will be described. FIG. 14 shows the same experimental results as in FIG. 13 in the case of using a Ru underlayer (the same thickness) instead of the underlayer Cu in the case of FIG. In the case of FIG. 14, unlike the case of FIG. 13, when the annealing temperature (T _a ) is relatively high, the unidirectional anisotropy constant J can be obtained even if the substrate temperature (T _sub ) is 250 ° C. The value of _k (erg / cm ² ) remains high, and no upper limit on the substrate temperature (T _sub ) is recognized. Therefore, in the case of the Ru underlayer, a preferable temperature range of the substrate temperature (T _sub ) for obtaining a good unidirectional anisotropy constant J _k (erg / cm ² ) is at least 100 ° C. or more, preferably 150 ° C. or more. It is.

  In the case of the Ru underlayer, the upper limit of the substrate temperature is improved compared to the Cu underlayer because the melting point of Ru is higher than that of Cu and the Mn-Ir film is formed at a high substrate temperature. In addition, it is considered that the reaction with the underlayer hardly occurs. In any case, it is generally considered that it is not preferable to set the substrate temperature to 400 ° C. or higher at which mutual diffusion of dissimilar metal laminated films occurs.

(Dependence of unidirectional anisotropy constant J _k on annealing heating temperature (T _a ))
FIG. 15 shows the experimental results regarding the annealing heating temperature (Ta) dependence of the unidirectional anisotropy constant Jk. FIG. 15 also relates to the exchange coupling element shown in FIG. The vertical axis in FIG. 15 represents each unidirectional anisotropy constant J _k (erg / cm ² ) at 170 ° C., 130 ° C. and room temperature (RT), and the horizontal axis represents the annealing heating temperature (T _a ) (° C. ).

As is apparent from FIG. 15, the preferable temperature range of the annealing heating temperature (Ta) is 280 to 360 ° C. in order to obtain a good unidirectional anisotropy constant Jk (erg / cm ² ).

(Dependence of unidirectional anisotropy constant J _k on Mn-Ir composition)
FIG. 16 shows the experimental results regarding the dependency of the unidirectional anisotropy constant J _{k on} the Mn—Ir composition. The horizontal axis of FIG. 16 represents the atomic percentage of Ir in Mn—Ir, and the vertical axis represents the annealing heating temperatures (T _a ) of 300 ° C., 280 ° C., 250 ° C. and immediately after deposition without heating (As deposited). Each unidirectional anisotropy constant J _k (erg / cm ² ) is shown. The substrate temperature (T _sub ) was 170 ° C.

As is clear from FIG. 16, the composition ratio of Ir in the Mn—Ir alloy, which is preferable for obtaining a good unidirectional anisotropy constant Jk (erg / cm ² ), is 20 to 33 atomic%, more preferably. Is 25-30 atomic%.

(Example of temperature characteristics of magnetic characteristics of exchange coupling elements)
FIG. 17 shows an example of magnetic characteristics such as the unidirectional anisotropy constant Jk and blocking temperature TB of the exchange coupling element. The vertical axis in FIG. 17 represents each unidirectional anisotropy constant Jk (erg / cm ² ) when the substrate temperature (Tsub) is 170 ° C. and room temperature (RT), and the horizontal axis is the operating temperature of the exchange coupling element ( ° C). In FIG. 17, the blocking temperature TB is shown on the upper right shoulder of each curve along the plotted data. Note that the heating condition in the annealing process in FIG. 17 is the heating temperature (Ta) = 320 ° C., which corresponds to the case of Ta = 320 ° C. in the data shown in FIG.

As is apparent from FIG. 17, for example, when the substrate temperature (T _sub) is a temperature 170 ° C., the blocking temperature T _B is as high as 360 ° C., also unidirectional anisotropy constant J _k (erg / cm ²⁾ Is 1.3 at maximum, and the unidirectional anisotropy constant Jk (erg / cm ² ) does not decrease so much even when the use temperature (° C.) of the exchange coupling element is the practical maximum value (about 150 ° C.). The value exceeding 1.0 is maintained.

The cross-sectional schematic diagram of embodiment of the typical exchange coupling element which concerns on this invention. The plane schematic diagram of the film-forming apparatus for exchange coupling element manufacture of this invention. The schematic diagram of the infrared heat processing apparatus for exchange coupling element manufacture of this invention. 1 is a schematic cross-sectional view of a spin valve magnetoresistive element according to the present invention. The schematic cross section of the tunnel type magnetoresistive element in connection with this invention. FIG. 3 is a perspective view of a recording / reproducing separated type magnetic head including a GMR type reproducing head according to the present invention. FIG. 3 is a diagram showing a main part of a GMR reproducing head according to the present invention. 1 is a cross-sectional view of a memory cell as a main part of a magnetic memory according to the present invention. The schematic cross section of the structure of the exchange coupling element in the Example of this invention. The figure which shows an example of the measurement result of the X-ray-diffraction profile concerning the Example of this invention. The figure which shows the correlation with atomic% of Ir in Mn-Ir, and Neel temperature _TN (degreeC). The figure which shows an example of the measurement result of the average in-plane crystal grain size in connection with the Example of this invention. The figure which concerns on the Example of this invention and shows the experimental result (in the case of base layer Cu) regarding the substrate temperature Tsub dependence of the unidirectional anisotropy constant Jk. The figure which concerns on the Example of this invention and shows the experimental result (in the case of base layer Ru) regarding the substrate temperature Tsub dependence of the unidirectional anisotropy constant Jk. Involved in an embodiment of the present invention, shows the experimental results on the annealing heating temperature T _a dependency of the unidirectional anisotropy constant J _k. Involved in an embodiment of the present invention, shows the experimental results on Mn-Ir composition dependency of the unidirectional anisotropy constant J _k. The figure which shows an example of the temperature characteristic of the magnetic characteristic of the exchange coupling element in connection with the Example of this invention. The figure which showed the antiferromagnetic layer film thickness ( _dAF ) dependence of the unidirectional anisotropy constant ( _Jk ) disclosed by the nonpatent literature 1 as a function of heat processing temperature ( _Ta ). The figure which showed the annealing process time (t _a ) dependence of the unidirectional anisotropy constant (J _k ) disclosed in Non-Patent Document 1 as a function of the antiferromagnetic layer thickness (d _AF ). The figure which shows the antiferromagnetic layer film thickness ( _dAF ) dependence of the unidirectional anisotropy constant ( _Jk ) disclosed by the nonpatent literature 1. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exchange coupling element 2 Substrate 4 Antiferromagnetic layer 5 Ferromagnetic layer 10,800 Spin valve type magnetoresistive element 50,904 Tunnel type magnetoresistive element 811 GMR type reproducing head

Claims (11)

In an exchange coupling device in which an antiferromagnetic layer and a ferromagnetic layer exchange-coupled to the antiferromagnetic layer are sequentially stacked on a substrate, the antiferromagnetic layer is composed of an ordered phase (Mn ₃ Ir). An exchange coupling element comprising:   2. The exchange coupling element according to claim 1, wherein the Mn—Ir alloy has an Ir composition ratio of 20 to 33 atomic%.   The exchange coupling element according to claim 1 or 2, wherein an average in-plane crystal grain size of the Mn-Ir alloy in the antiferromagnetic layer is 9 nm (90 Å) or more.   The exchange coupling element according to claim 1, further comprising an underlayer between the base and the antiferromagnetic layer.   Manufacture of an exchange coupling element in which an antiferromagnetic thin film layer made of an Mn-Ir alloy and a ferromagnetic thin film layer exchange-coupled to the antiferromagnetic thin film layer are sequentially formed on a substrate with or without an underlayer. In the method, when forming the antiferromagnetic thin film layer, the substrate is heated to a predetermined substrate temperature that is predetermined in order to form an ordered phase of an Mn—Ir alloy, and the antiferromagnetic A method for manufacturing an exchange coupling element, wherein annealing is performed after the thin film layer is formed.   The predetermined substrate temperature when forming the antiferromagnetic thin film layer on the substrate via the underlayer is at least 100 ° C. or more when the underlayer material is Ru, and 100 to 180 when the underlayer material is Cu. The method for producing an exchange coupling element according to claim 5, wherein the temperature is set to ° C.   The method for manufacturing an exchange coupling element according to claim 5 or 6, wherein the heat treatment temperature of the antiferromagnetic layer thin film during the annealing treatment is 280 to 360 ° C.   A spin valve magnetoresistive element comprising the exchange coupling element according to any one of claims 1 to 4.   A tunneling magnetoresistive element comprising the exchange coupling element according to claim 1.   5. A magnetic head comprising the exchange coupling element according to claim 1. A magnetic memory comprising the tunnel-type magnetoresistive element according to claim 9.

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