In-plane magnetization film, in-plane magnetization film multilayer structure, hard bias layer, magnetoresistance effect element, and sputtering target

Abstract

The present application provides a film that can achieve a coercive force Hc of 2.00 kOe or more and a residual magnetization Mrt per unit area of 2.00 memu / cm 2 The in-plane magnetization film has a thickness of 20 nm or more and 80 nm or less, contains 45 at% or more and 80 at% or less of the metal Co, contains 20 at% or more and 55 at% or less of the metal Pt, contains 3 vol% or more and 25 vol% or less of the oxide with respect to the entirety of the in-plane magnetization film, and has an average particle diameter in the in-plane direction of the magnetic crystal grains of 15 nm or more and 30 nm or less.

Description

Technical Field

[0001] This invention relates to in-plane magnetized films, multilayer structures of in-plane magnetized films, hard bias layers, magnetoresistive elements, and sputtering targets. More specifically, it relates to achieving a coercivity Hc of 2.00 kOe or higher and a remanence Mrt of 2.00 memu / cm² per unit area without heating the substrate (hereinafter sometimes referred to as heated film deposition). 2 The above-described CoPt-oxide-based in-plane magnetizing films, CoPt-oxide-based in-plane magnetizing film multilayer structures, and hard bias layers having the aforementioned in-plane magnetizing films or in-plane magnetizing film multilayer structures are also described. Furthermore, they relate to magnetoresistive effect devices and sputtering targets associated with the aforementioned CoPt-oxide-based in-plane magnetizing films, CoPt-oxide-based in-plane magnetizing film multilayer structures, or hard bias layers. The aforementioned CoPt-oxide-based in-plane magnetizing films and Pt-oxide-based in-plane magnetizing film multilayer structures can be used as hard bias layers for magnetoresistive effect devices.

[0002] It is assumed that if the coercivity Hc is above 2.00 kOe and the remanence Mrt per unit area is 2.00 memu / cm, then... 2 The hard bias layer described above has coercivity and remanence per unit area that are equivalent to or greater than those of the hard bias layer of existing magnetoresistive effect elements. In this application, the "remanence per unit area" of the in-plane magnetization film refers to the value obtained by multiplying the remanence per unit volume of the in-plane magnetization film by the thickness of the in-plane magnetization film.

[0003] It should be noted that, in this application, a hard bias layer refers to a thin-film magnet that applies a bias magnetic field to a magnetic layer (hereinafter sometimes referred to as a free magnetic layer) that exerts a magnetoresistance effect.

[0004] In addition, in this application, metal Co is sometimes abbreviated as Co, metal Pt as Pt, and metal Ru as Ru. Other metallic elements are sometimes similarly referred to.

[0005] In addition, boron (B) is also included in the category of metallic elements in this application. Background Technology

[0006] Magnetic sensors are currently used in many fields, and magnetoresistive elements are one of the most widely used magnetic sensors.

[0007] A magnetoresistive element has a magnetic layer (free magnetic layer) that exerts the magnetoresistive effect and a hard bias layer that applies a bias magnetic field to the magnetic layer (free magnetic layer). The hard bias layer is required to stably apply a magnetic field of a specified magnitude to the free magnetic layer.

[0008] Therefore, high coercivity and remanence are required for hard bias layers.

[0009] However, the coercivity of the hard bias layer of existing magnetoresistive effect elements is about 2 kOe (e.g., in Patent Document 1). Figure 7 ), hoping to achieve its coercivity.

[0010] In addition, the expected remanence per unit area is approximately 2 memu / cm. 2 The above (for example, paragraph 0007 of Patent Document 2).

[0011] As a potential solution to these problems, one example is the technique described in Patent Document 3. The technique described in Patent Document 3 involves oriented a magnetic material with its easy magnetization axis oriented along its length by a seed layer (a composite seed layer comprising a Ta layer and a metal layer having a face-centered cubic (111) crystal structure or a hexagonal densest (001) crystal structure) disposed between a sensor stack (a stack having a free magnetic layer) and a hard bias layer. This aims to improve the coercivity of the hard bias layer. However, the desired magnetic properties of the hard bias layer are not achieved. Furthermore, in this method, the seed layer disposed between the sensor stack and the hard bias layer needs to be thickened to improve the coercivity. Therefore, this structure also suffers from the problem that the magnetic field applied to the free magnetic layer in the sensor stack weakens.

[0012] Furthermore, Patent Document 4 describes the use of FePt in the magnetic material used for the hard bias layer, and describes a FePt hard bias layer having a Pt or Fe seed layer and a Pt or Fe capping layer. Patent Document 4 proposes a structure in which the Pt or Fe in the seed layer and capping layer, and the FePt in the hard bias layer, are mixed together during annealing at an annealing temperature of approximately 250°C to approximately 350°C. However, the heating process required to form this hard bias layer needs to consider its impact on other already laminated films, and this heating process is something to be avoided as much as possible.

[0013] Patent document 5 shows an optimization of the annealing temperature, which can be reduced to approximately 200°C. It demonstrates a coercivity of over 3.5 kOe for the hard bias layer, but a remanence of approximately 1.2 memu / cm² per unit area. 2 This does not satisfy the aforementioned magnetic properties desired by the hard bias layer.

[0014] Patent Document 6 describes a magnetic recording medium for longitudinal recording, in which the magnetic layer is a granular structure consisting of ferromagnetic grains with a hexagonal close-packed structure and non-magnetic grain boundaries mainly composed of oxides surrounding the ferromagnetic grains. However, there are no examples of using such a granular structure as a hard bias layer in a magnetoresistive element. Furthermore, the technology described in Patent Document 6 aims to reduce the signal-to-noise ratio, a key issue in magnetic recording media, by using non-magnetic layers between the magnetic layers to create multiple magnetic layers. However, the magnetic layers above and below are antiferromagnetically coupled, making it a structure unsuitable for improving the coercivity of the magnetic layers.

[0015] Existing technical documents

[0016] Patent documents

[0017] Patent Document 1: Japanese Patent Application Publication No. 2008-283016

[0018] Patent Document 2: Japanese Patent Publication No. 2008-547150

[0019] Patent Document 3: Japanese Patent Application Publication No. 2011-008907

[0020] Patent Document 4: U.S. Patent Application Publication No. 2009 / 0274931A1

[0021] Patent Document 5: Japanese Patent Application Publication No. 2012-216275

[0022] Patent Document 6: Japanese Patent Application Publication No. 2003-178423 Summary of the Invention

[0023] The problem that the invention aims to solve

[0024] When applying the technology to practical magnetoresistive devices, the sensor stack (a stack with a free magnetic layer) and the hard bias layer are preferably as thin as possible, and it is also preferable not to heat-form the film.

[0025] The inventors believe that, based on the above conditions, in order to obtain a coercivity (approximately 2 kOe) and remanence per unit area (approximately 2 memu / cm²) of the hard bias layer of a magnetoresistive element that exceeds current performance, 2The hard bias layer requires exploration of elements and compounds different from those used in existing hard bias layers. Furthermore, this invention considers the possibility of applying oxides to CoPt-based in-plane magnetization films. On the other hand, in CoPt-oxide-based in-plane magnetization films, the magnetic sites are the CoPt alloy magnetic grains, not the grain boundaries composed of oxides. Therefore, the inventors considered whether a low amount of oxide in the CoPt-oxide-based in-plane magnetization film could improve magnetic properties such as coercivity Hc and remanence Mrt per unit area.

[0026] The present invention was made in view of the above-mentioned problems, in order to provide a coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm² per unit area without heat-forming the film. 2 In addition to the above-mentioned in-plane magnetized films, in-plane magnetized film multilayer structures, and hard bias layers, magnetoresistive effect elements and sputtering targets related to the above-mentioned in-plane magnetized films, in-plane magnetized film multilayer structures, or hard bias layers are also provided as supplementary topics.

[0027] Methods for solving problems

[0028] The present invention addresses the above-mentioned problems through the following methods: in-plane magnetization film, in-plane magnetization film multilayer structure, hard bias layer, magnetoresistive effect element and sputtering target.

[0029] That is, the in-plane magnetizing film of the present invention is an in-plane magnetizing film used as a hard bias layer of a magnetoresistive effect element, characterized in that it contains metal Co, metal Pt and oxide, has a thickness of 20 nm or more and 80 nm or less, contains 45 atomic% or more and 80 atomic% or less of metal Co and 20 atomic% or more and 55 atomic% or less of metal Pt relative to the total metal composition of the in-plane magnetizing film, contains 3 vol% or more and 25 vol% or less of the above-mentioned oxide relative to the entire in-plane magnetizing film, and the average grain size of the magnetic grains in the in-plane direction of the in-plane magnetizing film is 15 nm or more and 30 nm or less.

[0030] Here, regarding the in-plane magnetized film and the accompanying base film and other components of the present invention, the term "up and down" is interpreted as referring to the state in which the base film, on which the in-plane magnetized film is stacked, is arranged horizontally with the base film at its lowest position.

[0031] Furthermore, the "average grain size in the in-plane direction of the magnetic grains of the in-plane magnetized film" is calculated using the method described in the "Method for determining the average grain size in the in-plane direction of the CoPt alloy magnetic grains in the (F)CoPt in-plane magnetized film (Examples 1-14, Comparative Examples 1 and 2)" section under [Examples]. The same applies to other parts of this application.

[0032] The aforementioned in-plane magnetization film can be configured as a granular structure consisting of CoPt alloy grains and grain boundaries of the aforementioned oxides.

[0033] Here, grain boundary refers to the boundary of a grain.

[0034] The oxides mentioned above may be oxides containing at least one of the oxides of Ti, Si, W, B, Mo, Ta, and Nb.

[0035] The aforementioned in-plane magnetized film may contain boron in an amount of 0.5 atomic% or more and 3.5 atomic% or less relative to the metal composition.

[0036] The first aspect of the in-plane magnetized film multilayer structure of the present invention is an in-plane magnetized film multilayer structure used as a hard bias layer for magnetoresistive effect elements. It is characterized by having two or more in-plane magnetized films and a non-magnetic intermediate layer with a hexagonal close-packed crystal structure. The non-magnetic intermediate layer is disposed between the in-plane magnetized films, and the adjacent in-plane magnetized films sandwiching the non-magnetic intermediate layer are ferromagnetically coupled to each other. The in-plane magnetized films contain metal Co, metal Pt, and oxides. Relative to the total metal content of the in-plane magnetized films, it contains 45 atomic% or more and 80 atomic% or less of metal Co, 20 atomic% or more and 55 atomic% or less of metal Pt, and 3 vol% or more and 25 vol% or less of the aforementioned oxides relative to the total in-plane magnetized films. The average in-plane grain size of the magnetic grains in the in-plane direction of the in-plane magnetized films is 15 nm or more and 30 nm or less, and the total thickness of the two or more in-plane magnetized films is 20 nm or more.

[0037] The second aspect of the in-plane magnetized film multilayer structure of the present invention is an in-plane magnetized film multilayer structure used as a hard bias layer for magnetoresistive effect elements. It is characterized by having two or more in-plane magnetized films and non-magnetic intermediate layers, the non-magnetic intermediate layers being disposed between the in-plane magnetized films, and the adjacent in-plane magnetized films sandwiching the non-magnetic intermediate layers being ferromagnetically coupled to each other. The in-plane magnetized films contain Co, Pt, and oxides. Relative to the total metal composition of the in-plane magnetized films, it contains 45 atomic% or more and 80 atomic% or less of Co, 20 atomic% or more and 55 atomic% or less of Pt, and 3 vol% or more and 25 vol% or less of the aforementioned oxides relative to the total in-plane magnetized films. The average in-plane grain size of the magnetic grains in the in-plane direction of the in-plane magnetized films is 15 nm or more and 30 nm or less. The coercivity of the in-plane magnetized film multilayer structure is 2.00 kOe or more, and the remanence per unit area is 2.00 memu / cm. 2 above.

[0038] In this application, the non-magnetic interlayer refers to the non-magnetic layer disposed between the in-plane magnetized films.

[0039] In this application, ferromagnetic coupling refers to coupling based on exchange interactions that occur when the spins of adjacent magnetic layers (here, the aforementioned in-plane magnetized film) sandwiching a nonmagnetic intermediate layer become parallel (in the same direction).

[0040] Furthermore, in this application, the "remanence per unit area" of the in-plane magnetized film multilayer structure refers to the value obtained by multiplying the remanence per unit volume of the in-plane magnetized film contained in the in-plane magnetized film multilayer structure by the total thickness of the in-plane magnetized film contained in the in-plane magnetized film multilayer structure.

[0041] The aforementioned non-magnetic intermediate layer is preferably composed of Ru or a Ru alloy.

[0042] In the above-mentioned in-plane magnetized film multilayer structure, the in-plane magnetized film can be configured as a granular structure consisting of CoPt alloy grains and grain boundaries of the oxide.

[0043] In the first and second embodiments of the in-plane magnetized film multilayer structure of the present invention, the oxide can be an oxide containing at least one of oxides of Ti, Si, W, B, Mo, Ta, and Nb.

[0044] The standard thickness of each layer of the aforementioned in-plane magnetization film is 5 nm or more and 30 nm or less.

[0045] The hard bias layer of the present invention is characterized by having the above-described in-plane magnetization film or the above-described in-plane magnetization film multilayer structure.

[0046] The magnetoresistive effect element of the present invention is characterized by having the above-mentioned hard bias layer.

[0047] The sputtering target of the present invention is used when forming an in-plane magnetization film, which serves as at least a portion of a hard bias layer for magnetoresistive effect elements, by room temperature deposition. It is characterized by containing metal Co, metal Pt, and oxides; relative to the total metal composition of the sputtering target, it contains 50 atomic% or more and 85 atomic% or less of metal Co, 15 atomic% or more and 50 atomic% or less of metal Pt, and relative to the entire sputtering target, it contains 3 vol% or more and 25 vol% or less of the aforementioned oxides. The coercivity of the in-plane magnetization film to be formed is 2.00 kOe or more, and the remanence per unit area is 2.00 memu / cm. 2 above.

[0048] Invention Effects

[0049] According to the present invention, a coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm² per unit area can be provided without heat-forming the film. 2 The above magnetic properties include in-plane magnetization film, in-plane magnetization film multilayer structure, and hard bias layer. Attached Figure Description

[0050] Figure 1 This is a schematic cross-sectional view showing the state in which the in-plane magnetization film 10 of the first embodiment of the present invention is applied to the hard bias layer 14 of the magnetoresistive effect element 12.

[0051] Figure 2 This is a schematic cross-sectional view showing the state in which the in-plane magnetization film multilayer structure 20 of the second embodiment of the present invention is applied to the hard bias layer 26 of the magnetoresistive effect element 24.

[0052] Figure 3 It is a perspective view schematically showing the shape of the sheet sample 80 after the sheeting process.

[0053] Figure 4 This is an example of an observational image of a cross-section in the film thickness direction obtained by taking a picture using a scanning transmission electron microscope (see the observational image in Example 7).

[0054] Figure 5 The magnetization is performed in the thickness direction of the in-plane magnetization film in Reference Example 7 (along...). Figure 4 The results of line analysis (elemental analysis) performed on the black lines in the image.

[0055] Figure 6 This is an example of a planar observation image of an in-plane cross section obtained by taking a picture using a scanning transmission electron microscope (planar observation image of Example 1).

[0056] Figure 7 It is a schematic planar observation image used to illustrate the method for determining the average particle size. Detailed Implementation

[0057] (1) First implementation method

[0058] (1-1)Overview

[0059] Figure 1 This is a schematic cross-sectional view showing the state in which the in-plane magnetization film 10 of the first embodiment of the present invention is applied to the hard bias layer 14 of the magnetoresistive effect element 12. It should be noted that, in Figure 1 The description of the basement membrane (the in-plane magnetization membrane 10 is formed on the basement membrane) is omitted.

[0060] Here, as the magnetoresistive effect element 12, a tunnel-type magnetoresistive effect element is considered. Figure 1 The description of the structure shown is not limited to the application of the in-plane magnetization film 10 in the first embodiment to the hard bias layer of tunnel-type magnetoresistive effect elements. It can also be applied to, for example, the hard bias layer of giant magnetoresistive effect elements and anisotropic magnetoresistive effect elements.

[0061] The magnetoresistive element 12 (here, a tunnel-type magnetoresistive element) has two ferromagnetic layers (free magnetic layer 16 and pinned layer 52) separated by a very thin nonmagnetic tunnel barrier layer (hereinafter referred to as barrier layer 54). The pinned layer 52 is fixed by exchange coupling with an adjacent antiferromagnetic layer (not shown), thereby fixing its magnetization direction. The free magnetic layer 16 can freely rotate its magnetization direction relative to the magnetization direction of the pinned layer 52 in the presence of an external magnetic field. When the free magnetic layer 16 rotates relative to the magnetization direction of the pinned layer 52 by an external magnetic field, its resistance changes; therefore, by detecting this change in resistance, the external magnetic field can be detected.

[0062] The hard bias layer 14 applies a bias magnetic field to the free magnetic layer 16, stabilizing the magnetization direction axis of the free magnetic layer 16. The insulating layer 50 is formed of an electrically insulating material and suppresses the shunting of sensor current flowing vertically through the sensor stack (free magnetic layer 16, barrier layer 54, pinning layer 52) into the hard bias layers 14 on both sides of the sensor stack (free magnetic layer 16, barrier layer 54, pinning layer 52).

[0063] like Figure 1 As shown, the in-plane magnetization film 10 of this first embodiment can be used as a hard bias layer 14 of the magnetoresistive effect element 12, and can apply a bias magnetic field to the free magnetic layer 16 that exerts the magnetoresistive effect. The hard bias layer 14 is composed only of the in-plane magnetization film 10 of this first embodiment, and is composed of a single layer of the in-plane magnetization film 10.

[0064] The in-plane magnetizing film 10 of this first embodiment contains oxides and has a coercivity (coercivity of 2.00 kOe or more) that is equal to or greater than that of the hard bias layer of a conventional magnetoresistive element, and a remanence per unit area (2.00 memu / cm²). 2 The above describes a single-layer in-plane magnetization film. Specifically, the in-plane magnetization film 10 of this first embodiment is a CoPt-oxide-based in-plane magnetization film containing metallic Co, metallic Pt, and oxides. Relative to the total metal composition of the in-plane magnetization film, it contains 45 atomic% or more and 80 atomic% or less metallic Co, 20 atomic% or more and 55 atomic% or less metallic Pt, and 3 volume% or more and 25 volume% or less of the aforementioned oxides relative to the entire in-plane magnetization film. The thickness is 20 nm or more and 80 nm or less.

[0065] (1-2) Composition of the in-plane magnetization film 10

[0066] As described above, the in-plane magnetization film 10 of this first embodiment contains Co and Pt as metallic components, and also contains oxides.

[0067] Metals Co and Pt become constituent components of magnetic grains (tiny magnets) in in-plane magnetized films formed by sputtering.

[0068] Co is a ferromagnetic metallic element that plays a core role in the formation of magnetic grains (tiny magnets) in in-plane magnetized films. From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy grains (magnetic grains) in the sputtered in-plane magnetized film and maintaining the magnetism of the obtained in-plane magnetized film, the proportion of Co in the in-plane magnetized film of this embodiment is set to 45 atomic% or more and 80 atomic% or less relative to the total metal composition of the in-plane magnetized film. Furthermore, for the same reason, the proportion of Co in the in-plane magnetized film of this embodiment is preferably 45 atomic% or more and 70 atomic% or less relative to the total metal composition of the in-plane magnetized film, more preferably 45 atomic% or more and 60 atomic% or less.

[0069] Pt has the function of reducing the magnetic moment of the alloy by alloying with Co within a specified composition range, and has the function of adjusting the magnetic strength of the magnetic grains. On the other hand, it has the function of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy grains (magnetic grains) in the in-plane magnetized film obtained by sputtering, and increasing the coercivity of the in-plane magnetized film. From the viewpoint of increasing the coercivity of the in-plane magnetized film and adjusting the magnetism of the CoPt alloy grains (magnetic grains) in the obtained in-plane magnetized film, the content ratio of Pt in the in-plane magnetized film of this embodiment is set to be 20 atomic% or more and 55 atomic% or less relative to the total metal components in the in-plane magnetized film. In addition, for the same viewpoint, the content ratio of Pt in the in-plane magnetized film of this embodiment is preferably 30 atomic% or more and 55 atomic% or less relative to the total metal components in the in-plane magnetized film, more preferably 40 atomic% or more and 55 atomic% or less.

[0070] In addition, the metal composition of the in-plane magnetization film 10 in this embodiment may contain 0.5 atomic% or more and 3.5 atomic% or less of boron (B) in addition to Co and Pt. As demonstrated in the embodiments described later, by containing 0.5 atomic% or more and 3.5 atomic% or less of boron (B), the coercivity Hc of the in-plane magnetization film 10 is further improved.

[0071] The in-plane magnetization film 10 of this first embodiment contains at least one oxide selected from Ti, Si, W, B, Mo, Ta, and Nb. Furthermore, in the in-plane magnetization film 10, the CoPt alloy magnetic grains are separated from each other by a non-magnetic body composed of the oxides described above, forming a granular structure. That is, this granular structure consists of CoPt alloy grains and grain boundaries of the aforementioned oxides surrounding them.

[0072] Therefore, increasing the oxide content in the in-plane magnetization film 10 makes it easier to reliably separate the magnetic grains from each other and to make the magnetic grains more independent, which is preferable. From this viewpoint, the oxide content (average value of the oxide content in the entire in-plane magnetization film 10) contained in the in-plane magnetization film 10 of this first embodiment is set to 3% by volume or more. Furthermore, from the same viewpoint, the oxide content (average value of the oxide content in the entire in-plane magnetization film 10) contained in the in-plane magnetization film 10 of this first embodiment is preferably 4% by volume or more, and more preferably 5% by volume or more.

[0073] However, if the oxide content (average value of oxide content in the in-plane magnetization film 10 as a whole) is too high, the oxides will mix into the CoPt alloy grains (magnetic grains) and adversely affect the crystallinity of the CoPt alloy grains (magnetic grains), potentially increasing the proportion of structures other than hcp in the CoPt alloy grains (magnetic grains). From this perspective, it is standard to set the oxide content (average value of oxide content in the in-plane magnetization film 10 as a whole) in the in-plane magnetization film 10 of this first embodiment to 25% by volume or less. Furthermore, from the same perspective, the oxide content in the in-plane magnetization film 10 of this first embodiment is preferably 21% by volume or less, and more preferably 16% by volume or less.

[0074] Therefore, in this first embodiment, it is standard to set the oxide content (average value of oxide content in the entire in-plane magnetization film 10) contained in the in-plane magnetization film 10 to be 3% or more and 25% or less. In addition, the oxide content (average value of oxide content in the entire in-plane magnetization film 10) contained in the in-plane magnetization film 10 in this first embodiment is preferably 4% or more and 21% or less, and more preferably 5% or more and 16% or less.

[0075] In addition, when WO3 or MoO3 is contained as an oxide, the coercivity Hc of the in-plane magnetization film 10 increases, so it is preferable to contain WO3 or MoO3 as an oxide.

[0076] It should be noted that in the current in-plane magnetization films, elemental elements such as Cr, W, Ta, and B are used as grain boundary materials to separate the CoPt alloy grains (magnetic grains). Therefore, it is believed that the grain boundary materials are partially dissolved in the CoPt alloy. Consequently, it is considered that the crystallinity of the CoPt alloy grains (magnetic grains) in the current in-plane magnetization films is adversely affected, resulting in reduced saturation magnetization and remanence. The coercivity Hc and remanence values ​​of the current in-plane magnetization films are also considered to be negatively affected.

[0077] On the other hand, in the in-plane magnetization film 10 of this first embodiment, the grain boundary material is an oxide. Therefore, compared with the case where the grain boundary material is an element such as Cr, W, Ta, or B, the grain boundary material is less likely to dissolve in the CoPt alloy. As a result, the saturation magnetization and remanence of the CoPt alloy grains (magnetic grains) in the in-plane magnetization film 10 of this first embodiment increase. In addition, the coercivity Hc and remanence of the in-plane magnetization film 10 of this first embodiment also increase.

[0078] (1-3) Thickness of the in-plane magnetization film 10

[0079] When the thickness of the in-plane magnetization film 10 is reduced, the remanence Mrt per unit area tends to decrease. In addition, when the thickness of the in-plane magnetization film 10 is increased, the coercivity Hc tends to decrease. Therefore, from the point of view of balancing both, it is standard to set the thickness of the in-plane magnetization film 10 to be 20 nm or more and 80 nm or less.

[0080] (1-4) Average grain size in the in-plane direction of the CoPt alloy magnetic grains in the in-plane magnetization film 10

[0081] When the average grain size of the CoPt alloy magnetic grains in the in-plane direction of the in-plane magnetization film 10 increases, the ratio of (length of the CoPt alloy magnetic grains in the in-plane direction) to (length of the CoPt alloy magnetic grains in the film thickness direction) increases, and the shape of the CoPt alloy magnetic grains in the in-plane magnetization film 10 becomes flattened. As a result, due to shape magnetic anisotropy, the reverse magnetic field in the in-plane direction weakens, and the coercivity Hc of the in-plane magnetization film 10 increases.

[0082] Furthermore, when the average in-plane diameter of the CoPt alloy magnetic grains in the in-plane magnetization film 10 is large, the volume fraction of the grain boundaries relative to the overall in-plane magnetization film 10 decreases, the volume fraction of the CoPt alloy magnetic grains in the in-plane magnetization film 10 increases, the saturation magnetization Ms increases, and the remanence Mr increases. As a result, the remanence Mrt per unit area increases.

[0083] Therefore, from the viewpoint of increasing the coercivity Hc and remanence Mrt per unit area of ​​the in-plane magnetization film 10, it is standard to set the average grain size of the CoPt alloy magnetic grains in the in-plane direction of the in-plane magnetization film 10 to be 15 nm or more, preferably 18 nm or more, and more preferably 20 nm or more.

[0084] On the other hand, as shown in the embodiments and comparative examples described later, it is not possible to obtain an in-plane magnetization film 10 in which the average grain size of the CoPt alloy magnetic grains in the in-plane direction exceeds 30 nm. Therefore, the upper limit of the average grain size of the CoPt alloy magnetic grains in the in-plane direction in the in-plane magnetization film 10 is set to 30 nm.

[0085] It should be noted that when the average grain size of the CoPt alloy magnetic grains in the in-plane direction of the in-plane magnetization film 10 increases, the volume of the grain boundaries in the in-plane magnetization film 10 decreases. Therefore, the amount of oxide required in the in-plane magnetization film 10 can be reduced.

[0086] (1-5) Basement membrane

[0087] As the substrate film used in forming the in-plane magnetization film 10 of this first embodiment, it is preferably a substrate film made of metal Ru or Ru alloy having the same crystal structure (hexagonal close-packed structure hcp) as the magnetic particles (CoPt alloy particles) of the in-plane magnetization film 10 (hereinafter, sometimes referred to as Ru-based substrate film). The surface of the Ru-based substrate film is uneven, and when sputtering is performed using a CoPt-oxide sputtering target, the metal component tends to accumulate on the convex parts, and the oxide tends to accumulate on the concave parts. This is because, from the perspective of the sputtered particles flying toward the substrate film, the concave parts of the substrate film become shadows, so the metal tends to solidify on the convex parts of the substrate film, and therefore, the oxide precipitates in the concave parts of the substrate film.

[0088] Therefore, when the size of the protrusions on the surface of the Ru-based substrate film is large, the size of the CoPt alloy magnetic grains grown on the protrusions of the Ru-based substrate film tends to increase. On the other hand, as described in "(1-4) Average grain size of CoPt alloy magnetic grains in the in-plane direction in the in-plane magnetization film 10", by increasing the average grain size of the CoPt alloy magnetic grains in the in-plane direction in the in-plane magnetization film 10, the coercivity Hc and the remanence Mrt per unit area of ​​the in-plane magnetization film 10 can be increased. Therefore, it is preferable to use a Ru-based substrate film with a large size of surface protrusions when forming the in-plane magnetization film 10 of this first embodiment. For Ru-based substrate films, if the thickness is about 20 nm or more, the size of the surface protrusions increases to a certain extent. Therefore, it is preferable to use a Ru-based substrate film with a thickness of 20 nm or more, more preferably a Ru-based substrate film with a thickness of 25 nm or more, and particularly preferably a Ru-based substrate film with a thickness of 30 nm or more.

[0089] In addition, in order to ensure that the magnetic grains (Copt alloy particles) in the stacked in-plane magnetization film 10 are neatly oriented in-plane, it is preferable to arrange a large number of (10.0) planes or (11.0) planes on the surface of the Ru substrate film or Ru alloy substrate film used.

[0090] It should be noted that the substrate film used in forming the in-plane magnetization film of the present invention is not limited to a Ru substrate film or a Ru alloy substrate film. Any substrate film that can enable the CoPt magnetic grains of the obtained in-plane magnetization film to be oriented in-plane, promote the magnetic separation of the CoPt magnetic grains from each other, and is suitable for increasing the average grain size of the CoPt alloy magnetic grains in the in-plane direction of the in-plane magnetization film 10 can be used.

[0091] (1-6) Splash targets

[0092] The sputtering target used in fabricating the in-plane magnetization film 10 of this first embodiment is the same sputtering target used in forming the in-plane magnetization film 10, which serves as at least a portion of the hard bias layer 14 of the magnetoresistive effect element 12, by room temperature film deposition. It contains metal Co, metal Pt, and oxides. Relative to the total metal composition of the sputtering target, it contains 50 atomic% or more and 85 atomic% or less of metal Co, 15 atomic% or more and 50 atomic% or less of metal Pt, and 3 vol% or more and 25 vol% or less of the aforementioned oxides relative to the entire sputtering target. The coercivity of the formed in-plane magnetization film is 2.00 kOe or more, and the remanence per unit area is 2.00 memu / cm. 2 As described in “(E) Composition Analysis of In-Plane Magnetization Film (Reference Examples 1-8)”, the actual composition of the fabricated CoPt-oxide-based in-plane magnetization film (the composition obtained through composition analysis) deviates from the composition of the sputtering target used in the fabrication of the CoPt-oxide-based in-plane magnetization film. Therefore, the composition range of each element contained in the sputtering target is inconsistent with the composition range of each element contained in the in-plane magnetization film 10 of this first embodiment.

[0093] The description of the components of the sputtering target (metal Co, metal Pt and oxide) is the same as the description of the components of the in-plane magnetization film described in "(1-2) Components of the in-plane magnetization film 10" above, so the description is omitted.

[0094] (1-7) Method for forming in-plane magnetization film 10

[0095] The in-plane magnetized film 10 of this first embodiment is formed by sputtering on a predetermined base film (the base film described in the "(1-5) base film") using the sputtering target described in "(1-6) Sputtering Target" above. It should be noted that heating is not required during this film formation process, and the in-plane magnetized film 10 of this first embodiment can be formed by room temperature film formation.

[0096] (2) Second implementation method

[0097] Figure 2 This is a schematic cross-sectional view showing the state in which the in-plane magnetization film multilayer structure 20 of the second embodiment of the present invention is applied to the hard bias layer 26 of the magnetoresistive effect element 24.

[0098] Hereinafter, the in-plane magnetization film multilayer structure 20 of the second embodiment will be described. The composition of the in-plane magnetization film 10, the thickness of the in-plane magnetization film 10, the average grain size of the CoPt alloy magnetic grains in the in-plane direction of the in-plane magnetization film 10, the substrate film used to form the in-plane magnetization film 10, the sputtering target used to fabricate the in-plane magnetization film 10, and the method for forming the in-plane magnetization film 10 have been described in "(1) First Embodiment", so the description is omitted.

[0099] like Figure 2 As shown, the in-plane magnetization film multilayer structure 20 of the second embodiment of the present invention is formed as follows: a non-magnetic intermediate layer 22 is provided on the in-plane magnetization film 10 of the first embodiment, and the in-plane magnetization film 10 is stacked on the non-magnetic intermediate layer 22. Figure 2 In this case, only two in-plane magnetized films 10 are stacked, but it can also be configured to have three or more in-plane magnetized films 10 stacked by sandwiching a non-magnetic intermediate layer 22 between them.

[0100] In the in-plane magnetization film multilayer structure 20, the thickness of each layer of the in-plane magnetization film 10 is typically 5 nm or more and 30 nm or less. However, from the viewpoint of further increasing the coercivity Hc, the thickness of each layer of the in-plane magnetization film 10 is preferably 5 nm or more and 15 nm or less, more preferably 10 nm or more and 15 nm or less. Furthermore, to achieve a remanence Mrt of 2.00 meum / cm² per unit area... 2 Based on the above viewpoints, the total thickness of the in-plane magnetization film 10 is typically set to 20 nm or more. Furthermore, regarding the upper limit of the total thickness of the in-plane magnetization film 10, as described later, adjacent in-plane magnetization films 10, separated by the intercalation of the non-magnetic interlayer 22, are ferromagnetically coupled to each other. Therefore, even if the total thickness of the in-plane magnetization film 10 increases, theoretically the coercivity Hc will not decrease, and there is no upper limit. In fact, through the embodiments described later, it has been confirmed that the coercivity Hc is 2.00 kOe or more up to a total thickness of 60 nm for the in-plane magnetization film 10.

[0101] The in-plane magnetized film multilayer structure 20 of this second embodiment can be used as a hard bias layer 26 of the magnetoresistive effect element 24, and can apply a bias magnetic field to the free magnetic layer 28 that exerts the magnetoresistive effect.

[0102] The non-magnetic intermediate layer 22 is sandwiched between the in-plane magnetized films 10, which serves to separate the in-plane magnetized films 10 from each other and to multiply the in-plane magnetized films. By sandwiching the non-magnetic intermediate layer 22 to multiply the in-plane magnetized films, the coercivity Hc can be further improved while maintaining the value of the remanence Mrt.

[0103] The in-plane magnetized films 10, separated by the intercalation of the non-magnetic intermediate layer 22, are arranged such that their spins become parallel (in the same direction). This arrangement allows adjacent in-plane magnetized films 10, separated by the intercalation of the non-magnetic intermediate layer 22, to achieve ferromagnetic coupling. Therefore, the multilayer structure 20 of in-plane magnetized films can improve the coercivity Hc while maintaining the value of the remanence Mrt, exhibiting excellent coercivity Hc.

[0104] From the viewpoint of not impairing the crystal structure of the CoPt alloy magnetic grains, the metal used in the non-magnetic intermediate layer 22 is set to have the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic grains. Specifically, as the non-magnetic intermediate layer 22, it is preferable to use a metal Ru or a Ru alloy that has the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic grains in the in-plane magnetization film 10.

[0105] When the metal used in the non-magnetic intermediate layer 22 is a Ru alloy, the added element may be, for example, Cr, Pt, or Co. The range of the amount of these metals added is preferably set to the range in which the Ru alloy forms a hexagonal close-packed structure hcp.

[0106] Arc melting was performed to prepare a bulk sample of Ru alloy. X-ray diffraction peak analysis was conducted using an X-ray diffraction apparatus (XRD: SmartLab manufactured by Rigaku Corporation). The results showed that in the RuCr alloy, when the Cr addition amount was 50 atomic%, a mixed phase of hexagonal close-packed structure hcp and RuCr2 was confirmed. Therefore, when using RuCr alloy as the non-magnetic interlayer 22, setting the Cr addition amount to less than 50 atomic% is appropriate, preferably less than 40 atomic%, and more preferably less than 30 atomic%. Furthermore, in the RuPt alloy, when the Pt addition amount was 15 atomic%, a mixed phase of hexagonal close-packed structure hcp and RuCr2 was confirmed. The RuPt alloy is a mixed phase of a hexagonal close-packed structure (hcp) and a face-centered cubic structure (fcc) from Pt. Therefore, when using the RuPt alloy as the non-magnetic intermediate layer 22, it is appropriate to set the amount of Pt added to less than 15 atomic percent, preferably less than 12.5 atomic percent, and more preferably less than 10 atomic percent. Furthermore, in the RuCo alloy, a hexagonal close-packed structure (hcp) is formed regardless of the amount of Co added. However, when more than 40 atomic percent of Co is added, it becomes magnetic. Therefore, it is appropriate to set the amount of Co added to less than 40 atomic percent, preferably less than 30 atomic percent, and more preferably less than 20 atomic percent.

[0107] In addition, the standard thickness of the non-magnetic intermediate layer 22 is 0.3 nm or more and 3 nm or less.

[0108] Example

[0109] Hereinafter, embodiments, comparative examples, and reference examples used to demonstrate the present invention will be described.

[0110] In section (A) below, the effect of the average in-plane grain size of the CoPt alloy magnetic grains in the in-plane magnetized film of a CoPt-WO3 in-plane magnetized film monolayer on the coercivity Hc and the remanence Mrt per unit area was studied. In section (B) below, the effect of the average in-plane grain size of the CoPt alloy magnetic grains in the in-plane magnetized film of a CoPt-WO3 in-plane magnetized film multilayer on the coercivity Hc and the remanence Mrt per unit area was studied. In section (C) below, the effect of the oxide content in the in-plane magnetized film of a CoPt-WO3 in-plane magnetized film multilayer on the coercivity Hc and the remanence Mrt per unit area was studied. Furthermore, in (D) below, the coercivity Hc and remanence Mrt per unit area were measured when the oxide in the in-plane magnetization film 10 was B2O3 and when boron B was added as the metallic component of the in-plane magnetization film 10 in the CoPt-oxide in-plane magnetization film multilayer structure.

[0111] Furthermore, in section (E) below, to determine the degree of deviation between the actual composition (obtained through compositional analysis) of the fabricated CoPt-WO3 in-plane magnetization film and the composition of the sputtering target used in fabricating the CoPt-WO3 in-plane magnetization film, compositional analysis was performed using the CoPt-WO3 in-plane magnetization films of Reference Examples 1 to 8. The results showed that a deviation occurred between the composition of the fabricated in-plane magnetization film and the composition of the sputtering target used to fabricate the in-plane magnetization film.

[0112] The composition of the in-plane magnetized film of CoPt oxide in the examples and comparative examples described in (A) to (D) below was calculated by correcting the composition of the sputtering target used in the fabrication and adjusting for deviations in the composition identified in (E) below.

[0113] Furthermore, in section (F) below, a method for measuring the average grain size in the in-plane direction of the CoPt alloy magnetic grains in the CoPt in-plane magnetized film is specifically described.

[0114] <(A) Study on the influence of the average in-plane grain size of CoPt alloy magnetic grains in a CoPt-WO3 in-plane magnetized film monolayer structure on the coercivity Hc and remanence Mrt per unit area (Example 1, Comparative Example 1)>

[0115] In Example 1 and Comparative Example 1, a (Co-30Pt)-10 vol% WO3 sputtering target was used to fabricate a 30 nm thick (Co-34.7Pt)-11.0 vol% WO3 in-plane magnetization film monolayer structure. The thickness of the Ru substrate film used was set to 30 nm in Example 1 and 10 nm in Comparative Example 1. Then, the coercivity Hc, remanence per unit area Mrt, and average in-plane grain size of the CoPt alloy magnetic grains in the in-plane magnetization film were measured on the (Co-34.7Pt)-11.0 vol% WO3 in-plane magnetization film monolayer structures fabricated in Example 1 and Comparative Example 1.

[0116] The following is a detailed explanation.

[0117] First, a Ru substrate film was formed on a Si substrate using a sputtering method with a thickness of 30 nm (Example 1) and a thickness of 10 nm (Comparative Example 1) using an ES-3100W sputtering apparatus manufactured by Eiko Engineering Co., Ltd. It should be noted that the sputtering apparatus used in the embodiments and comparative examples of this application was the ES-3100W manufactured by Eiko Engineering Co., Ltd. for all film formations (Ru substrate film, in-plane magnetized film, Ru non-magnetic intermediate layer); the apparatus name will be omitted below.

[0118] In Example 1, a (Co-30Pt)-10 vol%WO3 sputtering target was used to form a 30 nm thick (Co-34.7Pt)-11.0 vol%WO3 in-plane magnetization monolayer structure on a 30 nm thick Ru substrate film by sputtering. In Comparative Example 1, a (Co-30Pt)-10 vol%WO3 sputtering target was used to form a 30 nm thick (Co-34.7Pt)-11.0 vol%WO3 in-plane magnetization monolayer structure on a 10 nm thick Ru substrate film by sputtering.

[0119] In these film formation processes (the formation processes of Ru substrate film and in-plane magnetized film), no substrate heating is performed; film formation is carried out at room temperature.

[0120] The hysteresis loops of the in-plane magnetized film monolayer structures of Example 1 and Comparative Example 1 were measured using a vibrating magnetometer (VSM: TM-VSM211483-HGC type manufactured by Tamagawa Corporation) (hereinafter referred to as vibrating magnetometer). The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loops. 3 Then, make the read remanence Mr (memu / cm) 3 Multiply by the total thickness of the fabricated CoPt in-plane magnetized film to calculate the remanence per unit area (mrt / cm²) of the fabricated in-plane magnetized film monolayer structure. 2 ).

[0121] In addition, in the in-plane magnetized film monolayer structures of Example 1 and Comparative Example 1, the average grain size in the in-plane direction of the CoPt alloy magnetic grains in the CoPt in-plane magnetized film was measured by the measurement method described in (F) below.

[0122] The results of Example 1 and Comparative Example 1 are shown in Table 1 below.

[0123] [Table 1]

[0124]

[0125] As shown in Table 1, the in-plane magnetization film of Example 1 is an in-plane magnetization film with a thickness of 30 nm containing metallic Co, metallic Pt, and oxides. The Co content, relative to the total metal composition (Co and Pt), is 45 atomic% to 80 atomic% or more, and the Pt content is 20 atomic% to 55 atomic% or more. The oxide content, relative to the entire in-plane magnetization film, is 3 vol% to 25 vol% or more. The average in-plane grain size of the CoPt alloy magnetic grains in this in-plane magnetization film is 20.4 nm, falling within the range of 15 nm to 30 nm. Therefore, the in-plane magnetization film of Example 1 is included within the scope of this invention, achieving a coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm² per unit area through room temperature film deposition without substrate heating. 2 The above magnetic properties.

[0126] On the other hand, the composition and thickness of the in-plane magnetization film of Comparative Example 1 are the same as those of the in-plane magnetization film of Example 1. However, the average in-plane grain size of the CoPt alloy magnetic grains in the in-plane magnetization film of Comparative Example 1 is 11.4 nm, which is not in the range of 15 nm or more and 30 nm or less. Therefore, the in-plane magnetization film of Comparative Example 1 is not included in the scope of the present invention. The coercivity Hc of the in-plane magnetization film of Comparative Example 1 is 1.81 kOe, which is less than 2.00 kOe. In addition, the remanence Mrt per unit area is 1.31 memu / cm. 2 Less than 2.00 memu / cm 2 It is believed that because the average grain size of the CoPt alloy magnetic grains in the in-plane magnetization film of Comparative Example 1 is as small as 11.4 nm in the in-plane direction, the coercivity Hc and the remanence per unit area Mrt are smaller.

[0127] <(B) Study on the influence of the average in-plane grain size of CoPt alloy magnetic grains in the in-plane magnetized film of a CoPt-WO3 multilayer structure on the coercivity Hc and remanence Mrt per unit area (Examples 2, 3, Comparative Example 2)>

[0128] The in-plane magnetization film multilayer structures formed in Examples 2, 3, and Comparative Example 2 are multilayer structures formed by stacking four layers of CoPt-WO3 in-plane magnetization film with a thickness of 15 nm, with a Ru non-magnetic interlayer with a thickness of 2 nm sandwiched in between. The thickness of the Ru substrate film used varies to 30 nm (Example 2), 100 nm (Example 3), and 10 nm (Comparative Example 1). The experimental data were obtained by differentiating the average grain size in the in-plane direction of the CoPt alloy magnetic grains in the in-plane magnetization film of the in-plane magnetization film multilayer structures of Examples 2, 3, and Comparative Example 2.

[0129] The following is a detailed explanation.

[0130] First, Ru substrate films were formed on Si substrates by sputtering with thicknesses of 30 nm (Example 2), 100 nm (Example 3), and 10 nm (Comparative Example 1).

[0131] Then, an in-plane magnetized film of (Co-34.7Pt)-11.0 vol% WO3 with a thickness of 15 nm is formed on the formed Ru substrate film by sputtering. A Ru non-magnetic intermediate layer with a thickness of 2 nm is formed on the formed 15 nm thick (Co-34.7Pt)-11.0 vol% WO3 in-plane magnetized film by sputtering (using a sputtering target of 100 atomic% Ru). An in-plane magnetized film of (Co-34.7Pt)-11.0 vol% WO3 with a thickness of 15 nm is formed on the formed 2 nm thick Ru non-magnetic intermediate layer by sputtering. The above operations are repeated to fabricate an in-plane magnetized film multilayer structure with four layers of CoPt in-plane magnetized films of a specified composition.

[0132] In these film formation processes (Ru substrate film, CoPt in-plane magnetized film and Ru non-magnetic intermediate layer formation processes), no substrate heating is performed; film formation is carried out at room temperature.

[0133] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 2, 3, and Comparative Example 2 were measured using a vibrating magnetometer. The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loops. 3 Then, make the read remanence Mr (memu / cm) 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film, the remanence per unit area (Mrt / cm²) of the fabricated multilayer in-plane magnetized film structure is calculated. 2 ).

[0134] In addition, the average in-plane grain size of the CoPt alloy magnetic grains in the fourth layer of CoPt in-plane magnetized film, counting from the Si substrate side, in the in-plane magnetized film multilayer structure of Examples 2, 3, and Comparative Example 2 was measured by the measurement method described in (F) below.

[0135] The results of Examples 2, 3 and Comparative Example 2 are shown in Table 2 below.

[0136] [Table 2]

[0137]

[0138] As shown in Table 2, the in-plane magnetization film multilayer structure of Examples 2 and 3 is formed by stacking four layers of 15nm thick CoPt in-plane magnetization film with a 2nm thick Ru nonmagnetic interlayer sandwiched in between. For the in-plane magnetization film of Examples 2 and 3, relative to the total metal composition (Co, Pt), the Co content is 45 atomic% or more and 80 atomic% or less, and the Pt content is 20 atomic% or more and 55 atomic% or less. The overall oxide content of the in-plane magnetized film is 3% to 25% by volume. The average in-plane grain size of the CoPt alloy magnetic grains in the in-plane magnetized film is 18.9 nm and 22.3 nm, respectively, falling within the range of 15 nm to 30 nm. The multilayer in-plane magnetized film structures of Examples 2 and 3 are included within the scope of this invention. A coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm² per unit area are achieved through room temperature film deposition without substrate heating. 2 The above magnetic properties.

[0139] On the other hand, regarding the in-plane magnetized film of Comparative Example 2, the composition, thickness, and number of layers are the same as those of the in-plane magnetized films of Examples 2 and 3. However, the average in-plane diameter of the CoPt alloy magnetic grains in the in-plane magnetized film of Comparative Example 2 is 10.8 nm, which is not within the range of 15 nm to 30 nm. Therefore, the in-plane magnetized film of Comparative Example 2 is not included in the scope of this invention, and the coercivity Hc is 1.27 kOe, which is less than 2.00 kOe. It is believed that because the average in-plane diameter of the CoPt alloy magnetic grains in the in-plane magnetized film of Comparative Example 2 is as small as 10.8 nm, the coercivity Hc is smaller.

[0140] <(C) Study on the influence of oxide content in the in-plane magnetized film on coercivity Hc and remanence Mrt per unit area in a CoPt-WO3 in-plane magnetized multilayer structure (Examples 4-11, 14)>

[0141] The in-plane magnetization film multilayer structure formed in Examples 4 to 11 and 14 is a multilayer structure formed by overlapping four layers of CoPt-WO3 in-plane magnetization film with a thickness of 15 nm and sandwiching a Ru nonmagnetic interlayer with a thickness of 2 nm in the middle. The experimental data were obtained by varying the oxide (WO3) content of the CoPt-WO3 in-plane magnetization film in the multilayer structure from 3.0 vol% to 20.6 vol%.

[0142] The following is a detailed explanation.

[0143] First, a Ru substrate film with a thickness of 60 nm is formed on a Si substrate by sputtering.

[0144] Then, a CoPt-WO3 in-plane magnetization film with a thickness of 15 nm is formed on the formed Ru substrate film by sputtering. A Ru non-magnetic intermediate layer with a thickness of 2 nm is formed on the formed 15 nm thick CoPt-WO3 in-plane magnetization film by sputtering (using a sputtering target with a thickness of 100 atomic percent Ru). A CoPt-WO3 in-plane magnetization film with a thickness of 15 nm is formed on the formed 2 nm thick Ru non-magnetic intermediate layer by sputtering. The above operations are repeated to fabricate an in-plane magnetization film multilayer structure with four layers of CoPt-WO3 in-plane magnetization films of a specified composition.

[0145] In these film formation processes (Ru substrate film, CoPt in-plane magnetized film and Ru non-magnetic intermediate layer formation processes), no substrate heating is performed; film formation is carried out at room temperature.

[0146] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 4-11 and 14 were measured using a vibrating magnetometer. The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loops. 3 Then, make the read remanence Mr (memu / cm) 3 Multiplying this by the total thickness of the CoPt in-plane magnetized film in the fabricated multilayer in-plane magnetized film structure, the remanence per unit area (Mrt / cm²) of the fabricated multilayer in-plane magnetized film structure is calculated. 2 ).

[0147] In addition, the average in-plane grain size of the CoPt alloy magnetic grains in the fourth CoPt in-plane magnetized film layer counting from the Si substrate side in the in-plane magnetized film monolayer structure of Examples 4 to 11, 14 was measured by the measurement method described below (F).

[0148] The results of Examples 4 to 11 and 14 are shown in Table 3 below.

[0149] [Table 3]

[0150]

[0151] As shown in Table 3, the in-plane magnetization film multilayer structure in Examples 4-11 and 14 is formed by stacking four layers of 15nm thick CoPt in-plane magnetization film with a 2nm thick Ru nonmagnetic interlayer sandwiched in between. For the in-plane magnetization film of Examples 4-11 and 14, the content of Co relative to the total metal composition (Co and Pt) is 45 atomic% or more and 80 atomic% or less, and the content of Pt is 20 atomic% or more and 55 atomic% or less. In the entire in-plane magnetized film, the oxide content is 3% by volume or more and 25% by volume or less. The average in-plane grain size of the CoPt alloy magnetic grains in the in-plane magnetized film is 16.7 nm to 25.9 nm, which is in the range of 15 nm or more and 30 nm or less. The multilayer structure of the in-plane magnetized film in Examples 4 to 11 and 14 is included in the scope of the present invention. A coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm per unit area are achieved by room temperature film formation without substrate heating. 2 The above magnetic properties.

[0152] The in-plane magnetization film multilayer structures of Examples 4-11 and 14 are included within the scope of this invention. However, as shown in Table 3, when the oxide (WO3) content is in the range of 3.0-20.6 vol%, the coercivity Hc tends to increase when the oxide (WO3) content is low. This is believed to be because a low oxide (WO3) content tends to increase the average grain size of the CoPt alloy magnetic grains in the in-plane direction.

[0153] <(D) Studies on the use of B2O3 in oxides and the presence of boron (B) in the metal composition (Examples 12, 13)>

[0154] In Example 12, an in-plane magnetized film multilayer structure was fabricated in the same manner as in Example 7, except that the oxide of the (Co-40Pt)-8 volume%WO3 sputtering target used in fabricating the in-plane magnetized film multilayer structure of Example 7 was replaced with B2O3, and the measurements were performed in the same manner as in Example 7.

[0155] In Example 13, the (Co-40Pt)-8 vol% B2O3 sputtering target containing 3 atomic% boron B as a metal component was used in the fabrication of the in-plane magnetized multilayer structure of Example 12. Otherwise, the in-plane magnetized multilayer structure was fabricated in the same manner as in Example 12, and the measurements were performed in the same manner as in Example 12.

[0156] Their results, together with those of Example 7, are shown in Table 4 below.

[0157] [Table 4]

[0158]

[0159] As shown in Table 4, by using the (Co-40Pt)-8 vol% WO3 sputtering target obtained by replacing the oxide of WO3 with B2O3 in the (Co-40Pt)-8 vol% B2O3 sputtering target used in the fabrication of the in-plane magnetized multilayer structure of Example 7 in Example 12, the coercivity Hc of the obtained in-plane magnetized multilayer structure was increased by about 1.3%, and the remanence Mrt per unit area was increased by about 24%.

[0160] Furthermore, by using a (Co-40Pt)-3B-8 volume%B2O3 sputtering target containing 3 atomic% boron B as a metal component in the (Co-40Pt)-8 volume%B2O3 sputtering target used in fabricating the in-plane magnetized multilayer structure of Example 12 in Example 13, the coercivity Hc of the obtained in-plane magnetized multilayer structure was increased by about 0.8%, and the remanence Mrt per unit area was reduced by about 6%.

[0161] <(E) Compositional Analysis of In-Plane Magnetization Film (Refer to Examples 1-8)>

[0162] Compositional analysis was performed on the in-plane magnetization films of Reference Examples 1 to 8 to confirm the degree of deviation between the actual composition of the fabricated CoPt-WO3 in-plane magnetization film (the composition obtained through compositional analysis) and the composition of the sputtering target used in the fabrication of the CoPt-WO3 in-plane magnetization film. The steps of the method for compositional analysis of the in-plane magnetization film of Reference Example 7 will be summarized below, followed by a detailed explanation of each step.

[0163] [Summary of the Steps] Line analysis for compositional analysis is performed along the thickness direction of the in-plane magnetized film. Regions with minimal compositional variation are selected from the line analysis locations along the thickness direction of the in-plane magnetized film (steps 1-4). Then, auxiliary lines are drawn to the left and right along the in-plane direction of the in-plane magnetized film for compositional analysis, using arbitrary measurement points included in these regions with minimal compositional variation. Line analysis for compositional analysis is performed on a 100nm straight line region along these auxiliary lines (step 5). Then, for each detected element, the average detection intensity of the 167 measurement points is calculated to determine the composition of the in-plane magnetized film (step 6). Steps 1-6 are explained in detail below.

[0164] [Step 1] The in-plane magnetized film, which is the object of analysis, is cut into two parallel planes in a direction orthogonal to the in-plane direction (the thickness direction of the in-plane magnetized film). Thinning is then performed using the FIB method (μ-sampling method) until the distance between the two parallel cut planes reaches approximately 30 nm. The shape of the thinned sample 80 after this thinning process is schematically shown below. Figure 3 In the middle. For example Figure 3 As shown, the shape of the thin-film sample 80 is approximately cuboid. The distance between the two parallel cut surfaces is approximately 30 nm. The length of one side of the cuboid-shaped thin-film sample 80 in the in-plane direction is approximately 30 nm, but the lengths of the other two sides can be appropriately determined as long as they can be observed using a scanning transmission electron microscope.

[0165] [Step 2] Using a scanning transmission electron microscope (STEM) capable of magnifying a 100 nm length to 2 cm (capable of magnification up to 200,000 times), the cut surface (the cut surface along the thickness direction of the in-plane magnetized film) of the sheet sample 80 obtained in Step 1 was photographed to obtain an observation image. The obtained observation image is rectangular, but the length direction of the rectangle is defined by the line where the uppermost surface of the in-plane magnetized film of the observed object intersects with the cut surface (the cut surface along the thickness direction of the in-plane magnetized film). An example of the obtained observation image (see the observation image in Example 7) is shown below. Figure 4 In obtaining the observation images of the in-plane magnetized film, the H-9500 manufactured by Hitachi High-Tech Co., Ltd. was used.

[0166] [Step 3] From the observation image obtained in Step 2, select any point contained in the in-plane magnetized film (in... Figure 4 (Represented by the black circle 82), and marks points 10 nm to the left and right of that point along the length of the observed image. Figure 4 (Represented by white circle 84). Then, line analysis for elemental analysis is performed along the thickness direction of the in-plane magnetized film, passing through the point of black circle 82, and line analysis for elemental analysis is performed along the thickness direction of the in-plane magnetized film, passing through the point of white circle 84. Thus, for three straight lines (one straight line passing through the thickness direction of the point of black circle 82 and two straight lines passing through the thickness direction of the point of white circle 84), line analysis for elemental analysis is performed along the thickness direction of the in-plane magnetized film (scanning in a top-down direction). When performing this line analysis for elemental analysis, it is necessary to select one black circle 82 and two white circles 84 in a way that the scanning range of the line analysis of the above three straight lines is, in principle, the entire range of the thickness direction of the in-plane magnetized film (in the case of a multilayer structure of in-plane magnetized film, this refers to the entire range from the uppermost in-plane magnetized film to the lowermost in-plane magnetized film).

[0167] In the compositional analysis of the in-plane magnetized film, energy-dispersive X-ray diffraction (EDX) was used as the elemental analysis method, and a JEM-ARM200F manufactured by Nippon Ekiden Co., Ltd. was used as the elemental analysis apparatus. The specific analytical conditions were set as follows: the X-ray detector was set to a Si drift detector, the X-ray emission angle was set to 21.9°, the solid angle was set to approximately 0.98 sr, a suitable spectroscopic crystal was used for each element, the measurement time was set to 1 second / point, the scan point interval was set to 0.6 nm, and the irradiation beam diameter was set to approximately 0.2 nmφ. Hereinafter, the conditions described in this section will sometimes be referred to as "the analytical conditions of step 3".

[0168] Will along Figure 4 The results of line analysis (elemental analysis) of the black line (the line passing through the thickness direction of the in-plane magnetized film at point 82) in the observed image (refer to Example 7) are shown below. Figure 5 In. Figure 5 In the diagram, the vertical axis represents the detection intensity of each element, and the horizontal axis represents the scanning position. Figure 5 The elements shown in the explanatory notes are those for which sufficient detection intensity can be confirmed. In the case of Reference Example 7, the elements for which sufficient detection intensity can be confirmed are Co, Pt, W, O, and Ru. Furthermore, in the compositional analysis of Reference Example 7, Kα1 rays were selected for the detection of Co and O, and Lα1 rays were selected for the detection of Pt, Ru, and W. Additionally, for each detection intensity, a correction was performed by subtracting the detection intensity from a pre-measured blank. Figure 4 The very end (bottommost) of the line analysis is the Si substrate. Theoretically, only Si and O produced by surface oxidation can be detected at this location. Therefore, detection values ​​other than Si and O detected at this location are considered unavoidable detection error values ​​in the device, and are thus set to indicate the presence of an element only if the detection intensity shows a value greater than this.

[0169] Reference Example 7 shows an in-plane magnetization film monolayer structure, formed using a sputtering target with a composition of (Co-30Pt)-10 vol% WO3, resulting in an in-plane magnetization film with a thickness of 30 nm. Furthermore, to prevent oxidation of the in-plane magnetization film, a 10 nm Ta layer is formed on the topmost layer, using a sputtering target of 100 atomic% Ta.

[0170] Depend on Figure 5The line analysis results show that Co, Pt, W, and O are mainly identified in the in-plane magnetized film, Ru is mainly identified in the base film, and Ta is mainly identified in the antioxidant layer. At the interfaces of the layers in contact with the in-plane magnetized film, due to the sputtering heat during film formation, some elements from adjacent layers are observed to diffuse into each other. However, by observing the distribution of the main elements in the in-plane magnetized film, it can be confirmed that the film formation was roughly in accordance with the design.

[0171] [Step 4] Based on the results of the line analysis performed in Step 3 (line analysis performed for elemental analysis in the thickness direction of the in-plane magnetized film), select the set of measurement points with minimal compositional variation. The set of measurement points with minimal compositional variation is the set of measurement points that satisfy the following conditions a to c.

[0172] Condition a) is a measurement point for any one of the three straight lines analyzed in step 3, and the combined detection intensity of Co and Pt exceeds 600 counts.

[0173] Condition b) When the total detection intensity of Co and Pt at the measurement point is set as X count, and the total detection intensity of Co and Pt at the next measurement point after the measurement at this measurement point (the measurement points adjacent to each other 0.6 nm below this measurement point) is set as Y count, the following condition must be met: Y / X-1<0.05.

[0174] Condition c) consists of 5 or more consecutive measurement points that satisfy conditions a and b.

[0175] The set of measurement points satisfying conditions a to c consists of 5 or more consecutive measurement points, thus forming a linear region of 0.6 nm × 4 = 2.4 nm or more. Therefore, the set of measurement points satisfying conditions a to c is a linear region in which at least one of Co and Pt can be stably detected within a range of 2.4 nm or more.

[0176] [Step 5] Select any one measurement point from the set of measurement points chosen in Step 4 as the reference point for the compositional analysis of the in-plane magnetized film (in... Figure 4 (Represented by a double white circle 86). Then, in a manner that includes this reference point, in the in-plane direction of the in-plane magnetized film for compositional analysis ( Figure 4 Draw auxiliary lines to the left and right from the length direction of the observed image (in the image). Figure 4 The black dashed line in the middle is 88). For the 100nm straight line region on this auxiliary line (in... Figure 4(Represented by a white dashed line 90), compositional analysis is performed under the same analytical conditions as in step 3. From the viewpoint of avoiding contamination caused by the previous line analysis in the thickness direction, the white dashed line 90, which is the object of compositional analysis, is set to a location where line analysis is achieved relative to the thickness direction (in...). Figure 4 The white line in the middle (84A) is more than 10nm apart (in Figure 4 (Represented by a white line 92 with arrows at both ends). In this compositional analysis, line analysis was performed for a linear region of 100 nm with a scan point interval of 0.6 nm, thus obtaining the analysis results of a total of 167 measurement points.

[0177] [Step 6] For each detected element, calculate the average detection intensity (count count) for the 167 measurement points. The ratio of the average detection intensity (count count) of each detected element is the composition ratio of each element in the in-plane magnetized film.

[0178] It should be noted that in EDX analysis, it is unavoidable that the fluorescent X-rays of light elements such as oxygen (O) are absorbed by the fluorescent X-rays of heavy elements such as platinum (Pt). However, in the in-plane magnetization film of the present invention, light elements such as oxygen (O) and heavy elements such as platinum (Pt) coexist. Therefore, regarding oxygen (O), all metals existing in oxide form (W in Reference Example 7) are transformed into a suitably oxidized state (WO3 in Reference Example 7), thereby determining the composition of the in-plane magnetization film.

[0179] The composition of the sputtering targets used in the fabrication of the in-plane magnetized films of Reference Examples 1 to 8 and the results of the composition analysis of the in-plane magnetized films of Reference Examples 1 to 8 are shown in Table 5 below.

[0180] [Table 5]

[0181] Composition of a sputtering target Results of compositional analysis of in-plane magnetization film Reference Example 1 <![CDATA[(Co-20Pt)-30 vol% WO3]]> <![CDATA[(Co-24.1Pt)-31.2 vol% WO3]]> See Example 2 <![CDATA[(Co-20Pt)-30 vol% WO3]]> <![CDATA[(Co-24.5Pt)-30.7 vol% WO3]]> See Example 3 <![CDATA[(Co-30Pt)-10 vol% WO3]]> <![CDATA[(Co-33.9Pt)-10.2 vol% WO3]]> See Example 4 <![CDATA[(Co-30Pt)-10 vol% WO3]]> <![CDATA[(Co-33.6Pt)-9.8 vol% WO3]]> See Example 5 <![CDATA[(Co - 20Pt) - 10 vol% WO3]]> <![CDATA[(Co-22.8Pt)-10.3 vol% WO3]]> See Example 6 <![CDATA[(Co-45Pt)-10 vol% WO3]]> <![CDATA[(Co-52.4Pt)-10.5 vol% WO3]]> See Example 7 <![CDATA[(Co-30Pt)-10 vol% WO3]]> <![CDATA[(Co-34.5Pt)-10.6 vol% WO3]]> See Example 8 <![CDATA[(Co-40Pt)-20 vol% WO3]]> <![CDATA[(Co-46.7Pt)-21.0 vol% WO3]]>

[0182] As shown in Table 5, a deviation occurs between the composition of the sputtering target and the composition of the in-plane magnetization film made using the sputtering target. Therefore, this deviation is corrected to determine the composition of the CoPt-WO3 in-plane magnetization film in the embodiments and comparative examples described in (A) to (C) above.

[0183] It should be noted that in Examples 12 and 13, boron (B) and B₂O₃ were added to the in-plane magnetized film. However, boron (B) is a light element with a small atomic number, and therefore, it cannot be detected by EDX analysis. Therefore, regarding the composition of the in-plane magnetized film in Examples 12 and 13, the composition ratio of Co and Pt can be determined, but the content of boron (B) and B₂O₃ cannot be determined.

[0184] In addition, Figure 4In the text, the circular marks or straight lines represented by symbols 82, 84, 84A, 86, 88, 90, and 92 are for the purpose of explaining the composition analysis method and do not correspond to the actual parts being measured.

[0185] <(F) Method for determining the average in-plane grain size of CoPt alloy magnetic grains in in-plane magnetized films (Examples 1-14, Comparative Examples 1 and 2)>

[0186] In Examples 1-14 and Comparative Examples 1 and 2, the average in-plane grain size of CoPt alloy magnetic grains in the CoPt in-plane magnetized film was measured. The steps of the measurement method are briefly described below, followed by a detailed explanation of each step. The results from Example 1 are used for this explanation. In this explanation, the CoPt alloy magnetic grains will be referred to as "magnetic particles".

[0187] [Summary of the Steps] Line analysis for compositional analysis is performed along the thickness direction of the in-plane magnetized film. Regions with minimal compositional variation are selected from the line analysis locations along the thickness direction of the in-plane magnetized film (steps 1-4). Then, these regions with minimal compositional variation are sliced ​​(the outermost surface is the in-plane surface). Planar observation images are obtained from two or more locations on this outermost in-plane surface using a scanning transmission electron microscope (step 5). In each obtained planar observation image, four straight lines of 150 nm length are drawn horizontally and vertically, representing nine squares with a side length of 50 nm. The particle size is measured using a cutting method with a total of eight straight lines. This particle size measurement is performed on two or more planar observation images, and the average particle size obtained by averaging the results of the particle size measurements for all planar observation images is taken as the average particle size in the in-plane direction (step 6).

[0188] The method for selecting the parts with less variation in composition through steps 1 to 4 is the same as steps 1 to 4 in the above-mentioned “(E) Composition analysis of in-plane magnetized film (refer to Examples 1 to 8)”. Therefore, the contents of steps 5 and 6 will be explained in detail below.

[0189] [Step 5] Thinning is performed on the outermost layer of the region with minimal compositional variation selected in steps 1-4 (the region along the thickness direction of the in-plane magnetization film). Using a scanning transmission electron microscope, the outermost layer of the in-plane magnetization film after thinning, with a thickness of approximately 10 nm to 20 nm, is photographed in the in-plane direction at a length magnified from 30 nm to 2 cm. The 30 nm is converted to pixels in 472 pixels to obtain digital data of the planar observation image. This digital data of the planar observation image is obtained from at least two locations of the same sample after thinning. An example of the obtained planar observation image (the planar observation image of Example 1) is shown below. Figure 6 In obtaining planar images of in-plane magnetized films, an H-9500 micrometer manufactured by Hitachi High-Tech Co., Ltd. was used, with an accelerating voltage of 200 kV. It should be noted that oxides, being non-magnetic grain boundary materials, are more easily photographed as white due to their high oxygen content (a light element), while magnetic layers containing a high Pt content (a heavy element) are more easily photographed as black. Therefore, considering these factors, the contrast and brightness were appropriately adjusted. By appropriately adjusting the contrast and brightness, images such as... Figure 6 The image shown is a planar view.

[0190] [Step 6] In the planar observation images obtained in Step 5, draw four straight lines 300 each with a length of 150 nm in both the horizontal and vertical directions, representing nine squares with a side length of 50 nm each. These lines are respectively positioned relative to a total of eight straight lines 300 (in... Figure 6 (Represented by white dashed lines in the middle), particle size was measured using the cutting method described later. The average particle size was calculated for each of the eight straight lines 300. The average particle size obtained by averaging the average particle sizes calculated for each of the eight straight lines 300 was used as the average particle size for the planar observation image. Figure 6 The average particle size of the in-plane magnetized film of the sample is then determined. The particle size is then measured on all planar images obtained in step 5, and the average particle size obtained by averaging all the average particle sizes of the planar images obtained in step 5 is taken as the average particle size in the in-plane direction of the in-plane magnetized film of the sample.

[0191] For the cutting method, use Figure 7 The schematic diagram of the planar view image shown is explained in detail.

[0192] First, determine using the method described later. Figure 7 The magnetic particles 302 present in the planar observation image are used to classify the region in the planar observation image into areas containing magnetic particles 302 and areas outside of magnetic particles 302 (i.e., regions of grain boundary material). Then, the region is compared with the straight line 300 (…). Figure 7The number n of magnetic particles 302 in contact (represented by black lines) is divided by the length L of the straight line 300 and the value obtained is used as the average particle size in the in-plane direction with respect to the straight line 300.

[0193] In the specific case of magnetic particles, the image analysis software ImageJ 1.44p was used. The planar observation image ( Figure 6 The image data is read into the image analysis software mentioned above, and the planar observation image ( Figure 6 The brightness and darkness of each pixel in the image are screened into stages from 0 to 255 (0 is set to white and 255 is set to black). Binarization is performed to identify pixels with a brightness and darkness of 90 or higher as part of the magnetic particles (pixels identified as part of the magnetic particles (pixels with a brightness and darkness of 90 or higher) are set to "1", and pixels with a brightness and darkness of 89 or lower are set to "0").

[0194] Next, in the planar image that has undergone the above binarization process, as shown... Figure 6 As shown, four straight lines 300, each 150nm long, are drawn horizontally and vertically to depict nine squares with a side length of 50nm, for a total of eight straight lines 300. Then, for each pixel that touches a straight line 300, a binarized value (1 or 0) is obtained.

[0195] Then, as a final correction, the values ​​of these pixels are changed from "0" to "1" only when there are 7 or more consecutive "0" pixels, including those that change from "1" to "0", and when there are no more than 7 consecutive "0" pixels while keeping the values ​​of these pixels at "0". This is based on the following consideration: when the spacing between adjacent magnetic particles 302 (i.e., the width of the grain boundary based on the non-magnetic material) 304 is less than 6 pixels ((30nm / 472 pixels) × 6 pixels = approximately 0.38nm), adjacent magnetic particles 302 are magnetically coupled to each other (when the spacing between adjacent magnetic particles 302 is less than approximately 0.38nm, adjacent magnetic particles 302 are considered to be one particle in terms of magnetism).

[0196] It should be noted that, in Figure 6 The straight line represented by the symbol 300 is marked for the purpose of illustrating the method for determining the average particle size of magnetic particles, and does not correspond to the actual part where the measurement is performed.

[0197] Industrial availability

[0198] The in-plane magnetization film, the multilayer structure of the in-plane magnetization film, the hard bias layer, the magnetoresistive effect element, and the sputtering target of the present invention can achieve a coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm² per unit area without heating the film formation process. 2 The above magnetic properties have industrial applicability.

[0199] Symbol Explanation

[0200] 10…In-plane magnetization film

[0201] 12, 24… Magnetoresistive elements

[0202] 14, 26... Hard bias layers

[0203] 16, 28… Free magnetic layers

[0204] 20… In-plane magnetization film multilayer structure

[0205] 22…Non-magnetic intermediate layer

[0206] 40…basement membrane

[0207] 50… Insulation layer

[0208] 52…stapled layer

[0209] 54…Blocking layer

[0210] 80…thin-sheet sample

[0211] 82… Black circle (any point contained in the in-plane magnetized film)

[0212] 84… White circle (a point located 10 nm to the left and right of the black circle 82 along the length of the observed image)

[0213] 84A…white line

[0214] 86…Double white circle (reference point for compositional analysis of in-plane magnetized films)

[0215] 88… Black dashed line (an auxiliary line drawn along the length of the image from the double white circle 86 (reference point))

[0216] 90… White dashed line (a straight line region of 100nm on the black dashed line 88 (auxiliary line))

[0217] 92… The white line with arrows at both ends (indicating a distance of more than 10 nm relative to the white line 84A)

[0218] 300…straight line

[0219] 302…Magnetic particles

[0220] 304… The spacing between adjacent magnetic particles 302 (based on the width of the grain boundary of the non-magnetic material).

Claims

1. An in-plane magnetizing film, which is used as a hard bias layer for a magnetoresistive effect element, characterized in that, It contains metallic Co, metallic Pt, and oxides, with a thickness of 20 nm or more and 80 nm or less. The total metallic composition of the in-plane magnetized film contains 45 atomic% to 80 atomic% Co and 20 atomic% to 55 atomic% Pt. The oxide contains, relative to the entire in-plane magnetization film, 3% to 25% by volume. The average grain size of the magnetic grains in the in-plane direction of the in-plane magnetized film is greater than 15 nm and less than 30 nm.

2. The in-plane magnetization film as described in claim 1, characterized in that, It has a granular structure consisting of CoPt alloy grains and grain boundaries of the oxide.

3. The in-plane magnetization film as described in claim 1 or 2, characterized in that, The oxide comprises at least one oxide of Ti, Si, W, B, Mo, Ta, and Nb.

4. The in-plane magnetization film as described in claim 1 or 2, characterized in that, The in-plane magnetized film contains boron in an amount of 0.5 atomic% or more and 3.5 atomic% or less relative to the total metal content.

5. An in-plane magnetized film multilayer structure, which is used as a hard bias layer for a magnetoresistive effect element, characterized in that, It has two or more inner magnetization films and a nonmagnetic intermediate layer with a hexagonal close-packed crystal structure. The non-magnetic intermediate layer is disposed between the in-plane magnetized films, and the in-plane magnetized films sandwiching the non-magnetic intermediate layer are ferromagnetically coupled to each other. The in-plane magnetized film contains metallic Co, metallic Pt, and oxides. Relative to the total metallic composition of the in-plane magnetized film, it contains 45 atomic% to 80 atomic% metallic Co, 20 atomic% to 55 atomic% metallic Pt, and, relative to the entire in-plane magnetized film, 3 vol% to 25 vol% of the oxides. The average in-plane diameter of the magnetic grains in the in-plane direction of this in-plane magnetization film is greater than 15 nm and less than 30 nm. The combined thickness of the two or more inner magnetized films is 20 nm or more.

6. An in-plane magnetized film multilayer structure, which is used as a hard bias layer for magnetoresistive effect elements, characterized in that, It has two or more inner magnetized films and non-magnetic intermediate layers. The non-magnetic intermediate layer is disposed between the in-plane magnetized films, and the in-plane magnetized films sandwiching the non-magnetic intermediate layer are ferromagnetically coupled to each other. The in-plane magnetized film contains metallic Co, metallic Pt, and oxides. Relative to the total metallic composition of the in-plane magnetized film, it contains 45 atomic% to 80 atomic% metallic Co, 20 atomic% to 55 atomic% metallic Pt, and, relative to the entire in-plane magnetized film, 3 vol% to 25 vol% of the oxides. The average in-plane diameter of the magnetic grains in the in-plane direction of this in-plane magnetization film is greater than 15 nm and less than 30 nm. The coercivity of the in-plane magnetized multilayer structure is above 2.00 kOe, and the remanence per unit area is 2.00 memu / cm. 2 above.

7. The in-plane magnetized film multilayer structure as described in claim 5 or 6, characterized in that, The non-magnetic intermediate layer is composed of Ru or a Ru alloy.

8. The in-plane magnetized film multilayer structure as described in claim 5 or 6, characterized in that, The in-plane magnetized film has a granular structure consisting of CoPt alloy grains and the grain boundaries of the oxide.

9. The in-plane magnetized film multilayer structure as described in claim 5 or 6, characterized in that, The oxide comprises at least one oxide of Ti, Si, W, B, Mo, Ta, and Nb.

10. The in-plane magnetized film multilayer structure as described in claim 5 or 6, characterized in that, The thickness of each layer of the in-plane magnetization film is more than 5 nm and less than 30 nm.

11. A hard bias layer, characterized in that, It has an in-plane magnetized film as described in any one of claims 1 to 4 or an in-plane magnetized film multilayer structure as described in any one of claims 5 to 10.

12. A magnetoresistive effect element, characterized in that, It has the hard bias layer as described in claim 11.

13. A sputtering target used in forming an in-plane magnetized film, which serves as at least a portion of a hard bias layer for magnetoresistive effect elements, by room temperature deposition, characterized in that... Contains metals Co, Pt, and oxides. Relative to the total metal composition of the sputtering target, it contains 50 atomic% to 85 atomic% of Co and 15 atomic% to 50 atomic% of Pt. The oxide contains, relative to the entire sputtering target, 3% to 25% by volume. The coercivity of the in-plane magnetized film to be formed is above 2.00 kOe, and the remanence per unit area is 2.00 memu / cm. 2 above.

Images