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 magnetic layer having a coercive force Hc of 2.00 kOe or more and a residual magnetization Mrt per unit area of 2.00 memu / cm2 or more, which is achieved without using a non-magnetic underlayer for promoting in-plane orientation of the magnetic layer and without performing heat deposition 2 The above in-plane magnetization film, in-plane magnetization film multilayer structure, hard bias layer, magnetoresistance effect element, and sputtering target. The in-plane magnetization film has: a preliminary magnetic layer (12A) containing Co, Pt, and a non-magnetic grain boundary material and having a thickness of 1 to 32 nm; and a magnetic layer main portion (12B) formed on the preliminary magnetic layer (12A) and containing Co, Pt, and a non-magnetic oxide, the above non-magnetic grain boundary material of the preliminary magnetic layer (12A) containing at least one of a Zn oxide and a Ta oxide.

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-mentioned magnetic properties include in-plane magnetized films and in-plane magnetized film multilayer structures, hard bias layers having the above-mentioned in-plane magnetized films or in-plane magnetized film multilayer structures, and magnetoresistive effect elements and sputtering targets associated with them.

[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. Background Technology

[0005] Magnetic sensors are now used in many fields, and magnetoresistive elements are one of the most widely used magnetic sensors.

[0006] 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.

[0007] Therefore, high coercivity and remanence are required for hard bias layers.

[0008] 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.

[0009] In addition, the expected remanence per unit area is approximately 2 memu / cm. 2The above (for example, paragraph 0007 of Patent Document 2).

[0010] In order to form a hard bias layer that can stably apply a magnetic field of a specified magnitude or greater to the magnetoresistive element containing the free magnetic layer, conventionally, an in-plane magnetizing film with the c-axis of the hcp structure CoPt alloy oriented in-plane has been used. As a technique for obtaining such an in-plane magnetizing film, there is a technique that uses a non-magnetic substrate layer (Cr, Ti, Cr alloy, Ti alloy, etc.) that promotes the in-plane orientation of the c-axis of the hcp structure CoPt alloy (for example, paragraph 0028 of Patent Document 2).

[0011] However, in this technology, a non-magnetic substrate layer (Cr, Ti, Cr alloy, Ti alloy, etc.) is required to promote the in-plane orientation of the c-axis of the CoPt alloy with the hcp structure. The distance between the magnetoresistive element and the hard bias layer is equal to the thickness of the non-magnetic substrate layer, and the magnetic field applied by the hard bias layer to the magnetoresistive element is reduced.

[0012] Furthermore, as a technique that uses an in-plane magnetization film to align the c-axis of Co in-plane, there is a technique for in-plane magnetic recording films (for example, paragraph 0010 of Patent Document 3). However, this technique involves heating the substrate temperature to over 200°C to form the film. Magnetoresistive elements composed of extremely thin films are easily damaged by heating, so film formation accompanied by substrate heating is not suitable as a method for forming a hard bias layer.

[0013] As a film formation method that does not involve heating the substrate, there is a technique that uses a Ru substrate layer as the substrate layer for forming a Co-Pt-based in-plane magnetization film, and maintains a high gas pressure during the film formation of the Ru substrate layer to increase the coercivity Hc of the Co-Pt-based in-plane magnetization film formed on the Ru substrate layer (for example, paragraph 0016 of Patent Document 3 and Non-Patent Document 1). However, in this technique, in order to increase the coercivity Hc, the thickness of the Ru substrate layer needs to be increased to about 15 nm or more. The distance between the magnetoresistive element and the hard bias layer is an amount corresponding to the thickness of the non-magnetic Ru substrate layer, and the magnetic field applied by the hard bias layer to the magnetoresistive element is reduced. Therefore, the same problem exists as in the technique described in Patent Document 2.

[0014] Existing technical documents

[0015] Patent documents

[0016] Patent Document 1: Japanese Patent Application Publication No. 2008-283016

[0017] Patent Document 2: Japanese Patent Publication No. 2008-547150

[0018] Patent Document 3: Japanese Patent Application Publication No. 2003-123240

[0019] Non-patent literature

[0020] Non-Patent Literature 1: Hiroyuki Omori, Akihiro Maesaka, “Structure and Magnetic Properties of Co-Pt Films Using Ru Substrates”, Journal of the Japanese Society for Applied Magnetics, Vol. 26, No. 4, 2002, pp. 269-273 Summary of the Invention

[0021] The problem that the invention aims to solve

[0022] 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, which can be achieved without using a non-magnetic substrate layer for promoting in-plane orientation of the magnetic layer and without heat-forming the film. 2 The above-mentioned magnetic properties of in-plane magnetized films, in-plane magnetized film multilayer structures, and hard bias layers are the main topics, and the 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 the supplementary topics.

[0023] Methods for solving problems

[0024] This invention addresses the aforementioned problems and comprises an in-plane magnetized film, an in-plane magnetized film multilayer structure, a hard bias layer, a magnetoresistive effect element, and a sputtering target, as described below.

[0025] That is, the first aspect of the in-plane magnetization film of the present invention is an in-plane magnetization film used as a hard bias layer for a magnetoresistive effect element, characterized in that it has: an initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material with a thickness of 1 nm or more and 32 nm or less, wherein, relative to the total metal content, it contains metallic Co of 44 atomic% or more and 82 atomic% or less, metallic Pt of 18 atomic% or more and 56 atomic% or less, and relative to the total volume, it contains metallic Pt of 2.0 vol% or more and 31.0 vol% or more. The non-magnetic grain boundary material described above; and a magnetic layer body portion formed on the aforementioned initial magnetic layer and containing metallic Co, metallic Pt, and non-magnetic oxides, wherein, relative to the total metal composition, it contains metallic Co of 44 atomic% or more and 82 atomic% or less, metallic Pt of 18 atomic% or more and 56 atomic% or less, and relative to the total volume, it contains the aforementioned non-magnetic oxides of 2.0 vol% or more and 31.0 vol% or less, and the aforementioned non-magnetic grain boundary material of the aforementioned initial magnetic layer contains at least one of Zn oxide and Ta oxide.

[0026] The second aspect of the in-plane magnetization film of the present invention is as follows: In the in-plane magnetization film of the first aspect described above, the initial magnetic layer further contains metal Fe, and contains metal Co and metal Fe with a total of 44 atomic% or more and 82 atomic% or less relative to the total metal composition, and contains metal Pt with 18 atomic% or more and 56 atomic% or less.

[0027] The third aspect of the in-plane magnetization film of the present invention is as follows: in the in-plane magnetization film of the first aspect or the second aspect described above, the non-magnetic oxide of the main body of the magnetic layer contains boron oxide.

[0028] The fourth aspect of the in-plane magnetization film of the present invention is as follows: In the in-plane magnetization film of any of the first to third aspects described above, the initial magnetic layer is formed on a substrate layer with a surface roughness of 0.1 nm or more and 1.5 nm or less.

[0029] In this application, surface roughness refers to the arithmetic mean roughness Ra.

[0030] The fifth aspect of the in-plane magnetization film of the present invention is as follows: In the in-plane magnetization film of the fourth aspect described above, the substrate layer is an insulating layer.

[0031] The first aspect of the in-plane magnetization film multilayer structure of the present invention is an in-plane magnetization film multilayer structure used as a hard bias layer for a magnetoresistive effect element. It is characterized by having: an initial magnetic layer containing metallic Co, metallic Pt, and a non-magnetic grain boundary material with a thickness of 1 nm or more and 32 nm or less, wherein, relative to the total metal content, it contains metallic Co of 44 atomic percent or more and 82 atomic percent or less, metallic Pt of 18 atomic percent or more and 56 atomic percent or less, and relative to the total volume, it contains the aforementioned non-magnetic material of 2.0 vol percent or more and 31.0 vol percent or less. The material comprises: a grain boundary material; a non-magnetic initial intermediate layer formed on the initial magnetic layer; and a magnetic layer body formed on the non-magnetic initial intermediate layer and containing metal Co, metal Pt, and non-magnetic oxide, wherein, relative to the total metal composition, it contains 44 atomic% or more and 82 atomic% or less of metal Co, 18 atomic% or more and 56 atomic% or less of metal Pt, and relative to the total volume, it contains 2.0 vol% or more and 31.0 vol% or less of the aforementioned non-magnetic oxide, wherein the non-magnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide.

[0032] 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 a magnetoresistive effect element. It is characterized by having an initial magnetic layer, two or more magnetic layer main bodies, and a non-magnetic intermediate layer. The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material. Relative to the total metal content, it contains 44 atomic% to 82 atomic% metallic Co and 18 atomic% to 56 atomic% metallic Pt. Relative to the total volume, it contains 2.0 vol% to 31.0 vol% of the aforementioned non-magnetic grain boundary material. The thickness of the initial magnetic layer is 1 nm to 32 nm. The two or more magnetic layer main bodies... Each of the body portions contains metallic Co, metallic Pt, and non-magnetic oxides. Relative to the total metallic composition, it contains metallic Co of 44 atomic% to 82 atomic% and metallic Pt of 18 atomic% to 56 atomic% and the aforementioned non-magnetic oxides of 2.0 vol% to 31.0 vol% relative to the total volume. The lowest magnetic layer body portion of the two or more magnetic layer body portions is formed on the aforementioned initial magnetic layer. The aforementioned non-magnetic intermediate layers are disposed between the aforementioned magnetic layer body portions, and the adjacent magnetic layer body portions sandwiching the aforementioned non-magnetic intermediate layers are ferromagnetically coupled to each other. The non-magnetic grain boundary material of the aforementioned initial magnetic layer contains at least one of Zn oxide and Ta oxide.

[0033] Here, the lowest magnetic layer body among the two or more magnetic layer body portions is the magnetic layer body portion formed at the position closest to the initial magnetic layer among the two or more magnetic layer body portions.

[0034] The third embodiment of the in-plane magnetization film multilayer structure of the present invention is an in-plane magnetization film multilayer structure used as a hard bias layer for a magnetoresistive effect element. It is characterized by having an initial magnetic layer, a non-magnetic initial intermediate layer formed on the initial magnetic layer, two or more magnetic layer main bodies and non-magnetic intermediate layers. The initial magnetic layer contains metallic Co, metallic Pt, and a non-magnetic grain boundary material. Relative to the total metal content, it contains 44 atomic% or more and 82 atomic% or less of metallic Co, 18 atomic% or more and 56 atomic% or less of metallic Pt, and relative to the total volume, it contains 2.0 vol% or more and 31.0 vol% or less of the aforementioned non-magnetic grain boundary material. The thickness of the initial magnetic layer is 1 nm or more and 32 nm or less. Each of the two or more magnetic layer main bodies contains metallic Co, metallic Pt, and non-magnetic oxide. Relative to the total metal content, it contains metallic Co of 44 atomic% to 82 atomic% and metallic Pt of 18 atomic% to 56 atomic% and the aforementioned non-magnetic oxide of 2.0 vol% to 31.0 vol% relative to the total volume. The lowermost magnetic layer main body of the two or more magnetic layer main bodies is formed on the aforementioned non-magnetic initial intermediate layer. The aforementioned non-magnetic intermediate layers are disposed between the aforementioned magnetic layer main bodies, and the adjacent magnetic layer main bodies sandwiching the aforementioned non-magnetic intermediate layers are ferromagnetically coupled to each other. The non-magnetic grain boundary material of the aforementioned initial magnetic layer contains at least one of Zn oxide and Ta oxide.

[0035] The fourth aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: in the in-plane magnetized film multilayer structure of the first or third aspect described above, the non-magnetic initial intermediate layer is composed of Ru or a Ru alloy.

[0036] The fifth aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: in the in-plane magnetized film multilayer structure of the first aspect or the third aspect described above, the thickness of the non-magnetic initial intermediate layer is 0.3 nm or more and 2 nm or less.

[0037] The sixth aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: in the in-plane magnetized film multilayer structure of the second or third aspect described above, the non-magnetic intermediate layer is composed of Ru or a Ru alloy.

[0038] The seventh aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: in the in-plane magnetized film multilayer structure of the second or third aspect described above, the thickness of the non-magnetic intermediate layer is 0.3 nm or more and 2 nm or less.

[0039] The eighth aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: In any of the above-described aspects 1 to 7, the initial magnetic layer further contains metal Fe, and contains metal Co and metal Fe totaling 44 atomic% or more and 82 atomic% or less relative to the total metal composition, and contains metal Pt totaling 18 atomic% or more and 56 atomic% or less.

[0040] The ninth aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: in the in-plane magnetized film multilayer structure of any of the first to eighth aspects described above, the non-magnetic oxide of the main body of the magnetic layer contains boron oxide.

[0041] The tenth aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: In any of the above-described aspects 1 to 9, the initial magnetic layer is formed on a substrate layer with a surface roughness of 0.1 nm or more and 1.5 nm or less.

[0042] The eleventh aspect of the in-plane magnetized film multilayer structure of the present invention is as follows: In the in-plane magnetized film multilayer structure of the above-mentioned eleventh aspect, the substrate layer is an insulating layer.

[0043] The first aspect of the hard bias layer of the present invention is a hard bias layer characterized by having an in-plane magnetization film of the fifth aspect described above.

[0044] The second aspect of the hard bias layer of the present invention is a hard bias layer characterized by having an in-plane magnetization film multilayer structure as described in the eleventh aspect above.

[0045] The first aspect of the magnetoresistive effect element of the present invention is a magnetoresistive effect element characterized by having a hard bias layer as described in the first aspect.

[0046] The second aspect of the magnetoresistive effect element of the present invention is a magnetoresistive effect element characterized by having a hard bias layer as described in the second aspect.

[0047] The sputtering target of the present invention is a sputtering target used when forming an in-plane magnetized film as at least a portion of a hard bias layer serving as a magnetoresistive effect element by room temperature deposition. It is characterized by containing metallic Co, metallic Pt, and a non-magnetic grain boundary material. Relative to the total metal composition of the sputtering target, it contains 60 atomic% to 82 atomic% of metallic Co, 18 atomic% to 40 atomic% of metallic Pt, and, relative to the entire sputtering target, 6 vol% to 30 vol% of the aforementioned non-magnetic grain boundary material, wherein the non-magnetic grain boundary material contains at least one of Zn oxide and Ta oxide.

[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 can be provided without using a non-magnetic substrate layer for promoting in-plane orientation of the magnetic layer and without heat-forming the film. 2 In addition to the above-mentioned in-plane magnetization film, in-plane magnetization film multilayer structure, and hard bias layer, magnetoresistive effect elements and sputtering targets related to the above-mentioned in-plane magnetization film, in-plane magnetization film multilayer structure, or hard bias layer can also be provided. Attached Figure Description

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

[0051] Figure 2 This is a schematic cross-sectional view of a conventional magnetoresistive element 200.

[0052] Figure 3 This is a schematic cross-sectional view showing the magnetoresistive effect element 20, the in-plane magnetization film multilayer structure 22, and the hard bias layer 24 of the second embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetization film multilayer structure 22 of the second embodiment of the present invention is applied to the hard bias layer 24 of the magnetoresistive effect element 20.

[0053] Figure 4 This is a schematic cross-sectional view showing the magnetoresistive effect element 30, the in-plane magnetized film multilayer structure 32, and the hard bias layer 34 of the third embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetized film multilayer structure 32 of the third embodiment of the present invention is applied to the hard bias layer 34 of the magnetoresistive effect element 30.

[0054] Figure 5 This is a schematic cross-sectional view showing the magnetoresistive effect element 40, the in-plane magnetized film multilayer structure 42, and the hard bias layer 44 of the fourth embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetized film multilayer structure 42 of the fourth embodiment of the present invention is applied to the hard bias layer 44 of the magnetoresistive effect element 40.

[0055] Figure 6 The bar chart is based on the experimental results of Reference Examples 1 to 8, with the type of nonmagnetic grain boundary oxide as the horizontal axis and the coercivity Hc(kOe) as the vertical axis.

[0056] Figure 7The image (cross-sectional TEM photograph) is obtained by taking a vertical cross-section (a cross-section of the CoPt in-plane magnetization film (initial magnetic layer) of Reference Example 8 using a scanning transmission electron microscope.

[0057] Figure 8 The graph is based on the experimental results of Examples 1 to 6 and Comparative Example 1, with the thickness of the initial magnetic layer of the in-plane magnetization film as the horizontal axis and the coercivity Hc(kOe) as the vertical axis.

[0058] Figure 9 The graph is a graph of the experimental results of Examples 4, 7-15 and Comparative Examples 2 and 3, with the ZnO content in the initial magnetic layer of the in-plane magnetized film as the horizontal axis and the coercivity Hc(kOe) as the vertical axis.

[0059] Figure 10 The graph is constructed with the content of Pt (atomic %) of the initial magnetic layer relative to the total metal composition (Co and Pt) as the horizontal axis and the coercivity Hc (kOe) as the vertical axis. Detailed Implementation

[0060] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Here, a tunnel-type magnetoresistive element will be considered as a magnetoresistive element in an embodiment of the present invention, but the magnetoresistive element of the present invention is not limited to a tunnel-type magnetoresistive element. Furthermore, the in-plane magnetization film and hard bias layer of the present invention are not limited to hard bias layers applied to tunnel-type magnetoresistive elements; for example, they can also be applied to hard bias layers of giant magnetoresistive elements and anisotropic magnetoresistive elements.

[0061] (1) First Embodiment

[0062] (1-1) Schematic configuration of the magnetoresistive effect element 10 in the first embodiment

[0063] Figure 1 This is a schematic cross-sectional view showing the magnetoresistive effect element 10, the in-plane magnetization film 12, and the hard bias layer 14 of the first embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetization film 12 of the first embodiment of the present invention is applied to the hard bias layer 14 of the magnetoresistive effect element 10. Figure 2 This is a schematic cross-sectional view of the magnetoresistive effect element 200 in the existing example.

[0064] The magnetoresistive effect element 10 of this first embodiment (here, a tunnel-type magnetoresistive effect element) has an in-plane magnetization film 12 (hard bias layer 14), a magnetic shielding layer 50, a seed layer 52, an antiferromagnetic layer 54, a pinning layer 56, a blocking layer 58, a free magnetic layer 60, a capping layer 62, and an insulating layer 70.

[0065] Both the pinned layer 56 and the free magnetic layer 60 are ferromagnetic layers, separated by a very thin barrier layer 58 acting as a nonmagnetic tunneling barrier. The pinned layer 56 is fixed by exchange coupling with the adjacent antiferromagnetic layer 54, thus fixing its magnetization direction. The free magnetic layer 60 can freely rotate its magnetization direction relative to the magnetization direction of the pinned layer 56 in the presence of an external magnetic field. When the free magnetic layer 60 rotates relative to the magnetization direction of the pinned layer 56 through an external magnetic field, its resistance changes; therefore, by detecting this change in resistance, the external magnetic field can be detected. A seed layer 52 is provided on the magnetic shielding layer 50, and an antiferromagnetic layer 54 is provided on the seed layer 52. A cap layer 62 is provided on the free magnetic layer 60.

[0066] The hard bias layer 14 has the function of applying a bias magnetic field to the free magnetic layer 60 and stabilizing the magnetization direction axis of the free magnetic layer 60. In the magnetoresistive effect element 10 of this first embodiment, the in-plane magnetization film 12 constitutes the hard bias layer 14.

[0067] The insulating layer 70 is formed of an electrically insulating material and serves to suppress the shunting of sensor current flowing vertically through the sensor stack (free magnetic layer 60, barrier layer 58, pinning layer 56, antiferromagnetic layer 54) into the hard bias layers 14 on both sides of the sensor stack (free magnetic layer 60, barrier layer 58, pinning layer 56, antiferromagnetic layer 54). Specifically, the insulating layer 70 can be, for example, made of silicon oxide or aluminum oxide.

[0068] (1-2) Schematic configuration of the in-plane magnetization film 12 and hard bias layer 14 in the first embodiment

[0069] like Figure 1 As shown, in the magnetoresistive effect element 10 of this first embodiment, an in-plane magnetization film 12 is used as a hard bias layer 14, and the in-plane magnetization film 12 can apply a bias magnetic field to the free magnetic layer 60 that exerts the magnetoresistive effect. The hard bias layer 14 is composed only of the in-plane magnetization film 12 of this first embodiment.

[0070] The in-plane magnetization film 12 of this first embodiment is composed of an initial magnetic layer 12A and a magnetic layer main body portion 12B. Both the initial magnetic layer 12A and the magnetic layer main body portion 12B are in-plane magnetization films with a granular structure in which magnetic metal particles are separated by non-magnetic grain boundary material.

[0071] The initial magnetic layer 12A is a layer directly stacked on the insulating layer 70 and has the following functions: it promotes the growth of magnetic metal particles (CoPt alloy particles with an hcp structure) in the magnetic layer body 12B formed on the initial magnetic layer 12A so that the active easy magnetization axis (c-axis) is oriented in-plane; it well forms a columnar particle layer of CoPt alloy with an hcp structure having a c-axis in the in-plane direction in the magnetic layer body 12B; and the initial magnetic layer 12A itself also serves as part of the hard bias layer 14, applying a bias magnetic field to the free magnetic layer 60. As demonstrated in the [Examples] described later, it is important that the nonmagnetic grain boundary material of the initial magnetic layer 12A contains at least one of Zn oxide and Ta oxide in order for the initial magnetic layer 12A to perform these functions.

[0072] The magnetic layer body 12B is a magnetic layer formed on the initial magnetic layer 12A. As described in the text, it is the main body of most of the in-plane magnetization film 12 (hard bias layer 14) and has the function of applying a bias magnetic field to the free magnetic layer 60.

[0073] The in-plane magnetization film 12 of this first embodiment is constructed having an initial magnetic layer 12A and a magnetic layer main body portion 12B as described above. Therefore, when forming the in-plane magnetization film 12 of this first embodiment, even if a non-magnetic Ru substrate layer 202 with a thickness of about 15 nm or more is formed on the insulating layer 70 as conventionally, Figure 2 Even without forming the in-plane magnetization film 12, it still exhibits good magnetic properties. By forming an initial magnetic layer 12A, which is part of the in-plane magnetization film 12, directly on the insulating layer 70, and forming the main magnetic layer portion 12B, which is the remaining part of the in-plane magnetization film 12, the in-plane magnetization film 12 exhibits good magnetic properties (coercivity Hc of 2.00 kOe or more, remanence of 2.00 memu / cm² per unit area). 2 above).

[0074] This results in the in-plane magnetized film 12 exhibiting excellent magnetic properties (coercivity Hc above 2.00 kOe, remanence per unit area of ​​2.00 memu / cm). 2Based on the above viewpoints, the thickness of the initial magnetic layer 12A is typically 1 nm or more and 32 nm or less. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, the thickness of the initial magnetic layer 12A is preferably 2 nm or more and 30 nm or less, more preferably 8 nm or more and 20 nm or less. The initial magnetic layer 12A has a granular structure where magnetic metal is separated by non-magnetic grain boundary material, and is part of the in-plane magnetization film 12. Therefore, even when the thickness of the initial magnetic layer 12A is, for example, 30 nm, the distance between the free magnetic layer 60 and the in-plane magnetization film 12 is only an amount corresponding to the distance of the insulating layer 70 disposed between the free magnetic layer 60 and the in-plane magnetization film 12. Therefore, in the magnetoresistive effect element 10 of this first embodiment, the attenuation of the bias magnetic field applied by the hard bias layer 14 to the free magnetic layer 60 is small.

[0075] On the other hand, such as Figure 2 As shown, the conventional magnetoresistive effect element 200 has a non-magnetic Ru substrate layer 202 with a thickness of about 15 nm or more disposed on the insulating layer 70, and an in-plane magnetization film 204 disposed on the non-magnetic Ru substrate layer 202. Therefore, in addition to the insulating layer 70, there is a non-magnetic Ru substrate layer 202 with a thickness of about 15 nm or more between the free magnetic layer 60 and the in-plane magnetization film 204. The free magnetic layer 60 and the in-plane magnetization film 204 are separated not only by a distance corresponding to the thickness of the insulating layer 70, but also by a distance corresponding to the thickness of the non-magnetic Ru substrate layer 202. Compared with the magnetoresistive effect element 10 of this first embodiment, the distance between the free magnetic layer 60 and the in-plane magnetization film 204 of the conventional magnetoresistive effect element 200 is exactly more than the distance corresponding to the thickness of the non-magnetic Ru substrate layer 202. Therefore, in the existing magnetoresistive effect element 200, compared with the magnetoresistive effect element 10 of this first embodiment, the attenuation of the bias magnetic field applied by the hard bias layer 206 to the free magnetic layer 60 is greater.

[0076] (1-3) Composition of the initial magnetic layer 12A

[0077] As described above, the in-plane magnetization film 12 of this first embodiment is composed of an initial magnetic layer 12A and a magnetic layer main body 12B. Both the initial magnetic layer 12A and the magnetic layer main body 12B are in-plane magnetization films with a particle structure in which magnetic metal particles are separated by non-magnetic grain boundary materials.

[0078] In order for the initial magnetic layer 12A to perform the above-mentioned functions (promoting the growth of the magnetic metal particles (CoPt alloy particles with hcp structure) in the main body of the magnetic layer 12B so that the active easy magnetization axis (c axis) is oriented in the plane, forming a columnar particle layer of CoPt alloy with hcp structure having c axis in the plane in the main body of the magnetic layer 12B, and applying a bias magnetic field to the free magnetic layer 60 as part of the hard bias layer 14), the initial magnetic layer 12A contains at least one of Zn oxide and Ta oxide as a non-magnetic grain boundary material, and contains Co and Pt as metallic components.

[0079] Metals Co and Pt become constituent components of magnetic metal particles (tiny magnets) in the initial magnetic layer 12A of the in-plane magnetization film 12 formed by sputtering.

[0080] Co is a ferromagnetic metallic element that plays a core role in the formation of magnetic grains (tiny magnets) in the initial magnetic layer 12A of the in-plane magnetization film 12.

[0081] From the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy grains (magnetic grains) and maintaining the magnetism of the CoPt alloy grains (magnetic grains), the initial magnetic layer 12A contains Co with a total metal content of 44 atomic% or more and 82 atomic% or less relative to the initial magnetic layer 12A. From the above viewpoint, for a more preferred range of the Co content ratio in the initial magnetic layer 12A, it is preferably 55 atomic% or more and 80 atomic% or less relative to the total metal content of the initial magnetic layer 12A, and more preferably 65 atomic% or more and 75 atomic% or less.

[0082] 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 also has the function of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy grains (magnetic grains) in the initial magnetic layer 12A of the in-plane magnetization film 12 obtained by sputtering, and increasing the coercivity of the initial magnetic layer 12A of the in-plane magnetization film 12.

[0083] From the viewpoint of increasing the coercivity of the initial magnetic layer 12A and adjusting the magnetic strength of the CoPt alloy grains (magnetic grains) in the initial magnetic layer 12A, the initial magnetic layer 12A contains Pt with a total metal content of 18 atomic% or more and 56 atomic% or less relative to the total metal content of the initial magnetic layer 12A. From the above viewpoint, for a more preferred range of the Pt content ratio in the initial magnetic layer 12A, it is preferably 20 atomic% or more and 45 atomic% or less relative to the total metal content of the initial magnetic layer 12A, and more preferably 25 atomic% or more and 35 atomic% or less.

[0084] In addition, the initial magnetic layer 12A of the in-plane magnetization film 12 in this embodiment may contain Fe, in addition to Co and Pt, in an amount of 0.5 atomic% or more and 1.5 atomic% or less relative to the total metal composition of the initial magnetic layer 12A.

[0085] The initial magnetic layer 12A of the in-plane magnetization film 12 of this first embodiment contains at least one of Zn oxide and Ta oxide as its non-magnetic grain boundary material. Furthermore, in the initial magnetic layer 12A, due to the presence of at least one of Zn oxide and Ta oxide as its non-magnetic grain boundary material, the CoPt alloy magnetic grains are separated from each other, forming a granular structure. That is, the granular structure of the initial magnetic layer 12A consists of CoPt alloy grains and grain boundaries surrounding them formed by a non-magnetic grain boundary material containing at least one of Zn oxide and Ta oxide.

[0086] When the content of the aforementioned non-magnetic grain boundary material in the initial magnetic layer 12A is increased, it is easier to reliably separate the magnetic grains from each other and make the magnetic grains independent of each other. Therefore, from this point of view, it is standard to set the content of the aforementioned non-magnetic grain boundary material contained in the initial magnetic layer 12A of the in-plane magnetization film 12 of this first embodiment to 2.0 vol% or more relative to the overall volume of the initial magnetic layer 12A, preferably to 3.0 vol% or more, and more preferably to 4.0 vol% or more.

[0087] However, if the content of the aforementioned non-magnetic grain boundary material in the initial magnetic layer 12A is excessive, it is possible that the non-magnetic grain boundary material may be mixed into the CoPt alloy grains (magnetic grains), adversely affecting the crystallinity of the CoPt alloy grains (magnetic grains), and 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 content of the aforementioned non-magnetic grain boundary material contained in the initial magnetic layer 12A of the in-plane magnetization film 12 of this first embodiment to 31.0 vol% or less relative to the overall volume of the initial magnetic layer 12A, preferably to 15.0 vol% or less, and more preferably to 10.0 vol% or less.

[0088] Therefore, in this first embodiment, the content of the non-magnetic grain boundary material in the initial magnetic layer 12A is set to 2.0% or more and 31.0% or less relative to the overall volume of the initial magnetic layer 12A. It is standard to set it to 3.0% or more and 15.0% or less, and more preferably to 4.0% or more and 10.0% or less.

[0089] The nonmagnetic grain boundary material of the initial magnetic layer 12A of the in-plane magnetization film 12 of this first embodiment contains at least one of Zn oxide and Ta oxide, which is demonstrated in the [Examples] described later to be important in improving the magnetic properties (coercivity Hc and remanence per unit area Mrt) of the in-plane magnetization film 12.

[0090] (1-4) Composition of the main body of the magnetic layer 12B

[0091] As described above, the magnetic layer body 12B is a magnetic layer formed on the initial magnetic layer 12A. As stated in the text, it occupies most of the in-plane magnetization film 12 (hard bias layer 14) and has the function of applying a bias magnetic field to the free magnetic layer 60. In order to perform this function, the magnetic layer body 12B contains Co and Pt as metallic components and oxides as non-magnetic grain boundary materials.

[0092] Metals Co and Pt become constituent components of magnetic metal particles (tiny magnets) in the magnetic layer body 12B of the in-plane magnetization film 12 formed by sputtering.

[0093] As described above, Co is a ferromagnetic metallic element that plays a core role in the formation of magnetic grains (tiny magnets) in the magnetic layer body 12B of the in-plane magnetization film 12.

[0094] In the main body of the magnetic layer 12B, similar to the initial magnetic layer 12A, from the viewpoint of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy grains (magnetic grains) and maintaining the magnetism of the CoPt alloy grains (magnetic grains), the main body of the magnetic layer 12B contains Co with a total metal content of 44 atomic% or more and 82 atomic% or less relative to the main body of the magnetic layer 12B. From the above viewpoint, for the more preferred range of the Co content ratio in the main body of the magnetic layer 12B, relative to the total metal content of the initial magnetic layer 12A, it is preferably 55 atomic% or more and 80 atomic% or less, more preferably 65 atomic% or more and 75 atomic% or less.

[0095] As described above, 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 also has the function of increasing the magnetocrystalline anisotropy constant Ku of the CoPt alloy grains (magnetic grains) in the magnetic layer body 12B of the in-plane magnetization film 12 obtained by sputtering, and increasing the coercivity of the magnetic layer body 12B of the in-plane magnetization film 12.

[0096] From the viewpoint of increasing the coercivity of the magnetic layer body 12B and adjusting the magnetic strength of the CoPt alloy grains (magnetic grains) in the magnetic layer body 12B, the magnetic layer body 12B contains Pt with a total metal content of 18 atomic% or more and 56 atomic% or less relative to the total metal content of the magnetic layer body 12B. From the above viewpoint, for a more preferred range of the Pt content ratio in the magnetic layer body 12B, it is preferably 20 atomic% or more and 45 atomic% or less relative to the total metal content of the magnetic layer body 12B, and more preferably 25 atomic% or more and 35 atomic% or less.

[0097] The magnetic layer body 12B of the in-plane magnetization film 12 of this first embodiment contains oxide as a non-magnetic grain boundary material. Furthermore, in the magnetic layer body 12B, due to the oxide as a non-magnetic grain boundary material, the CoPt alloy magnetic grains are separated from each other, forming a granular structure. That is, the granular structure of the magnetic layer body 12B consists of CoPt alloy grains and grain boundaries surrounding them, which are composed of oxide as a non-magnetic grain boundary material.

[0098] Increasing the content of oxides, which are non-magnetic grain boundary materials, in the main body portion 12B of the magnetic layer makes it easier to reliably separate the magnetic grains from each other and make the magnetic grains independent of each other. Therefore, from this point of view, it is standard to set the content of oxides, which are non-magnetic grain boundary materials, contained in the main body portion 12B of the magnetic layer of the in-plane magnetization film 12 of this first embodiment to 2.0% or more by volume relative to the overall volume of the main body portion 12B of the magnetic layer, preferably to 3.0% or more by volume, and more preferably to 4.0% or more by volume.

[0099] However, if the content of oxides, which are non-magnetic grain boundary materials, in the magnetic layer main body 12B is too high, these oxides may be mixed into the CoPt alloy grains (magnetic grains), adversely affecting the crystallinity of the CoPt alloy grains (magnetic grains). This could potentially increase the proportion of structures other than hcp in the CoPt alloy grains (magnetic grains). From this perspective, it is standard to set the content of oxides, which are non-magnetic grain boundary materials, contained in the magnetic layer main body 12B of the in-plane magnetization film 12 of this first embodiment to 31.0% by volume or less relative to the overall volume of the magnetic layer main body 12B. Preferably, it is set to 15.0% by volume or less, and more preferably, it is set to 10.0% by volume or less.

[0100] Therefore, in this first embodiment, it is standard to set the content of oxides, which are non-magnetic grain boundary materials, in the magnetic layer main body 12B to be 2.0% or more and 31.0% or less relative to the overall volume of the magnetic layer main body 12B. In addition, the content of oxides, which are non-magnetic grain boundary materials, contained in the magnetic layer main body 12B is preferably set to 3.0% or more and 15.0% or less, and more preferably set to 4.0% or more and 10.0% or less.

[0101] Furthermore, when boron oxide is included as the oxide that serves as the non-magnetic grain boundary material in the main body of the magnetic layer 12B, the coercivity Hc of the main body of the magnetic layer 12B increases, and the coercivity Hc of the in-plane magnetization film 12 also increases. Therefore, it is preferable to include boron oxide as the oxide.

[0102] It should be noted that in existing in-plane magnetized 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 dissolved in the CoPt alloy to a certain extent. Consequently, it is believed that the crystallinity of the CoPt alloy grains (magnetic grains) in existing in-plane magnetized films is adversely affected, resulting in reduced saturation magnetization and remanence. Furthermore, it is believed that the coercivity Hc and remanence values ​​of existing in-plane magnetized films are negatively impacted.

[0103] On the other hand, in the magnetic layer main body 12B of the in-plane magnetization film 12 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 difficult to dissolve in the CoPt alloy. As a result, the saturation magnetization and remanence of the magnetic layer main body 12B of the in-plane magnetization film 12 of this first embodiment are increased, and the coercivity Hc and remanence of the in-plane magnetization film 12 of this first embodiment are also increased.

[0104] (1-5) Thickness of the in-plane magnetization film 12 (initial magnetic layer 12A and magnetic layer body 12B)

[0105] As described above, the "remanence per unit area" of the in-plane magnetization film is the value calculated by multiplying the remanence per unit volume of the in-plane magnetization film by its thickness. Therefore, if the thickness of the in-plane magnetization film is reduced, the remanence per unit area (Mrt) tends to decrease. Conversely, if the thickness of the in-plane magnetization film is increased, the coercivity (Hc) of the in-plane magnetization film tends to decrease due to the shape magnetic anisotropy effect. These conditions apply to both the initial magnetic layer 12A and the main body of the magnetic layer 12B.

[0106] Regarding the thickness of the initial magnetic layer 12A, as mentioned above, it is typically 1 nm or more and 32 nm or less. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, the thickness of the initial magnetic layer 12A is preferably 2 nm or more and 30 nm or less, and more preferably 8 nm or more and 20 nm or less.

[0107] Regarding the thickness of the magnetic layer main body 12B, it is typically 15 nm or more and 80 nm or less. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, the thickness of the magnetic layer main body 12B is preferably 20 nm or more and 60 nm or less, and more preferably 25 nm or more and 50 nm or less.

[0108] (1-6) Basal layer

[0109] As described above, in the prior art, a non-magnetic substrate (Cr, Ti, Cr alloy, Ti alloy, etc.) is used as the substrate layer for the Co-Pt-based in-plane magnetization film to promote the in-plane orientation of the c-axis of the CoPt alloy with the hcp structure (paragraph 0028 of Patent Document 2 described in the [Prior Art Documents] section). Furthermore, as described above, in other prior art, a non-magnetic Ru substrate layer is formed by applying a high gas pressure during film formation, and a Co-Pt-based in-plane magnetization film is formed on this non-magnetic Ru substrate layer, resulting in a thickness of approximately 15 nm or more, thereby increasing the coercivity Hc of the Co-Pt-based in-plane magnetization film (paragraph 0016 of Patent Document 3 and Non-Patent Document 1 described in the [Prior Art Documents] section). However, all of these technologies use a non-magnetic substrate layer. Therefore, even if an in-plane magnetized film is formed as a hard bias layer using these technologies, the distance between the magnetoresistive element and the hard bias layer is equal to the distance formed by the thickness of the non-magnetic substrate layer, and the magnetic field applied by the hard bias layer to the magnetoresistive element is reduced.

[0110] On the other hand, in the in-plane magnetization film 12 and the hard bias layer 14 formed by the in-plane magnetization film 12 of this first embodiment, a non-magnetic substrate layer for improving the magnetic properties of the formed in-plane magnetization film is not used. Instead, an initial magnetic layer 12A, which is part of the in-plane magnetization film 12 (hard bias layer 14), is formed directly on the insulating layer 70. That is, the insulating layer 70 becomes the substrate layer of the in-plane magnetization film 12 (hard bias layer 14). Therefore, for the hard bias layer 14 formed by the in-plane magnetization film 12 of this first embodiment, the magnetoresistive element is close to the free magnetic layer 60, and the reduction of the magnetic field applied to the free magnetic layer 60 is suppressed. In addition, it is demonstrated in the [Embodiments] described later that even if the in-plane magnetization film 12 of this first embodiment is formed directly on the insulating layer 70, good coercivity Hc can be obtained by using the predetermined initial magnetic layer 12A.

[0111] Furthermore, regarding the in-plane magnetization film 12 of this first embodiment, it has been demonstrated in the [Examples] described later that even if the surface roughness of the insulating layer 70, which serves as the substrate during formation, is extremely small, to a value of 0.1 nm or more and 1.5 nm or less, a good coercivity Hc can still be obtained. Generally, when the surface roughness of the non-magnetic substrate layer, which serves as the substrate during formation, is relatively large, it promotes the magnetic isolation of the Co-Pt alloy grains and easily increases the coercivity Hc.

[0112] Furthermore, for the in-plane magnetization film 12 of this first embodiment, since the surface roughness of the insulating layer 70, which serves as the substrate during formation, is extremely small, ranging from 0.1 nm to 1.5 nm, it is also possible to achieve a reduction in the surface roughness of the formed in-plane magnetization film 12. If the surface roughness of the formed in-plane magnetization film 12 is reduced, less labor is required when manufacturing it as a magnetoresistive element 10, and subsequent processes are easier to perform.

[0113] In the in-plane magnetization film 12 of this first embodiment, the effect described above can be obtained (even if the in-plane magnetization film 12 of this first embodiment is formed directly on the insulating layer 70 with a surface roughness of 0.1 nm or more and 1.5 nm or less, good coercivity Hc can be obtained) because the in-plane magnetization film 12 is composed of an initial magnetic layer 12A and a magnetic layer body portion 12B, and the initial magnetic layer 12A is composed of a non-magnetic grain boundary material containing at least one of Zn oxide and Ta oxide, as will be demonstrated in the [Examples] described later. However, the theoretical reason why the effect described above can be obtained by composing the initial magnetic layer 12A with a non-magnetic grain boundary material containing at least one of Zn oxide and Ta oxide is not yet clear at this stage.

[0114] (1-7) Splash target

[0115] The sputtering target used in forming the initial magnetic layer 12A of the in-plane magnetization film 12 of the first embodiment by room temperature deposition contains metallic Co, metallic Pt, and a non-magnetic grain boundary material. Relative to the total metallic composition of the sputtering target, it contains 60 atomic% to 82 atomic% metallic Co, 18 atomic% to 40 atomic% metallic Pt, and 6 vol% to 30 vol% of the aforementioned non-magnetic grain boundary material relative to the entire sputtering target. The non-magnetic grain boundary material contains at least one of Zn oxide and Ta oxide. As described in the [Examples] section below, the actual composition (obtained through compositional analysis) of the fabricated CoPt-oxide-based in-plane magnetization film deviates from the composition of the sputtering target used in fabricating the CoPt-oxide-based in-plane magnetization film. Therefore, the compositional range of each element contained in the sputtering target is inconsistent with the compositional range of each element contained in the initial magnetic layer 12A of the in-plane magnetization film 12 of the first embodiment.

[0116] (1-8) Method for forming the initial magnetic layer 12A

[0117] The initial magnetic layer 12A of the in-plane magnetization film 12 of this first embodiment is formed on the insulating layer 70 by sputtering using the sputtering target described in "(1-7) Sputtering Target". No heating is required during the formation of this initial magnetic layer 12A; the film is formed at room temperature. Furthermore, no heating is required during the sputtering process when forming the main magnetic layer 12B, and the in-plane magnetization film 12 of this first embodiment can be formed by room temperature film formation.

[0118] Furthermore, as described in “(1-6) Substrate Layer” above, in the formation of the in-plane magnetization film 12 in this first embodiment, a non-magnetic substrate layer for improving the magnetic properties of the formed in-plane magnetization film 12 is not used. Instead, an initial magnetic layer 12A is formed directly on the insulating layer 70 by sputtering, and a magnetic layer body portion 12B is formed on the formed initial magnetic layer 12A by sputtering, thereby forming the in-plane magnetization film 12.

[0119] (2) Second implementation method

[0120] Figure 3 This is a schematic cross-sectional view showing the magnetoresistive effect element 20, the in-plane magnetization film multilayer structure 22, and the hard bias layer 24 of the second embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetization film multilayer structure 22 of the second embodiment of the present invention is applied to the hard bias layer 24 of the magnetoresistive effect element 20.

[0121] Hereinafter, the in-plane magnetization film multilayer structure 22 of this second embodiment will be described, but for the same constituent elements as in the first embodiment, the same symbols will be used in principle, and the description will be omitted.

[0122] like Figure 3 As shown, the in-plane magnetization film multilayer structure 22 of the second embodiment of the present invention is formed as follows: an initial magnetic layer 22A is formed on the insulating layer 70, a non-magnetic initial intermediate layer 22C is formed on the initial magnetic layer 22A, and a magnetic layer main body portion 22B is formed on the non-magnetic initial intermediate layer 22C. Here, the composition and thickness of the initial magnetic layer 22A and the magnetic layer main body portion 22B are the same as those of the initial magnetic layer 12A and the magnetic layer main body portion 12B of the in-plane magnetization film 12 of the first embodiment, and therefore, the description is omitted in principle.

[0123] The in-plane magnetized film multilayer structure 22 of this second embodiment can be used as a hard bias layer 24 of the magnetoresistive effect element 20, and can apply a bias magnetic field to the free magnetic layer 60 that exerts the magnetoresistive effect.

[0124] The non-magnetic initial intermediate layer 22C is multi-layered by separating into an initial magnetic layer 22A and a magnetic layer main body 22B in the thickness direction. It is a layer that has the function of further improving the coercivity Hc while maintaining the value of remanence Mrt per unit area by reducing the thickness of a single magnetic layer while maintaining the total thickness of the magnetic layers.

[0125] The initial magnetic layer 22A and the main magnetic layer 22B, separated by the non-magnetic initial intermediate layer 22C, are arranged with their spins parallel (in the same direction). This arrangement allows the initial magnetic layer 22A and the main magnetic layer 22B to achieve ferromagnetic coupling, thus enabling the in-plane magnetized multilayer structure 22 to improve coercivity Hc while maintaining the remanence Mrt value per unit area, exhibiting excellent coercivity Hc.

[0126] From the viewpoint of not impairing the crystal structure of the CoPt alloy magnetic grains, the metal used in the non-magnetic initial intermediate layer 22C is set to have the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic grains. Specifically, as the non-magnetic initial intermediate layer 22C, Ru or a Ru alloy, which has the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic grains in the initial magnetic layer 22A and the main body of the magnetic layer 22B, can be appropriately used.

[0127] When the metal used in the non-magnetic initial intermediate layer 22C is a Ru alloy, the added element can be, for example, Cr, Pt, or Co. The range of the amount of these metals added can be set to the range of the Ru alloy when it has a hexagonal close-packed structure (hcp).

[0128] Arc melting was performed to prepare a block 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 when the Cr content in the RuCr alloy was 50 atomic%, a mixed phase of hexagonal close-packed structure hcp and RuCr2 was identified. Therefore, when using RuCr alloy in the non-magnetic initial intermediate layer 22C, setting the Cr content to less than 50 atomic% is appropriate, preferably less than 40 atomic%, and more preferably less than 30 atomic%. Furthermore, when the Pt content in the RuPt alloy was 15 atomic%, a mixed phase of hexagonal close-packed structure hcp and face-centered cubic structure fcc from Pt was identified. Therefore, when using RuPt alloy in the non-magnetic initial intermediate layer 22C, setting the Pt content to less than 15 atomic% is appropriate, preferably less than 12.5 atomic%, and more preferably less than 10 atomic%. Furthermore, in RuCo alloys, regardless of the amount of Co added, a hexagonal close-packed structure (hcp) is formed. However, if more than 40 atomic% of Co is added, it becomes a magnetic material. Therefore, it is appropriate to set the amount of Co added to less than 40 atomic%, preferably less than 30 atomic%, and more preferably less than 20 atomic%.

[0129] Regarding the thickness of the non-magnetic initial intermediate layer 22C, if the thickness of the non-magnetic initial intermediate layer 22C is too thin, it may not be able to perform the above-mentioned function (multilayering by separating the initial magnetic layer 22A and the magnetic layer main body 22B in the thickness direction, and further improving the coercivity Hc by reducing the thickness of a single magnetic layer while maintaining the total thickness of the magnetic layers). Therefore, the thickness of the non-magnetic initial intermediate layer 22C is typically 0.3 nm or more, preferably 0.5 nm or more, and more preferably 0.7 nm or more.

[0130] On the other hand, the thinner the non-magnetic initial intermediate layer 22C is, the closer the magnetic layer main body 22B is to the free magnetic layer 60, and the reduction of the magnetic field applied to the free magnetic layer 60 by the hard bias layer 24 composed of the in-plane magnetized film multilayer structure 22 is suppressed. Therefore, the thickness of the non-magnetic initial intermediate layer 22C is typically 2 nm or less, preferably 1.5 nm or less, and more preferably 1.2 nm or less.

[0131] Therefore, the thickness of the non-magnetic initial intermediate layer 22C is typically 0.3 nm or more and 2 nm or less, preferably 0.5 nm or more and 1.5 nm or less, and more preferably 0.7 nm or more and 1.2 nm or less.

[0132] (3) Third implementation

[0133] Figure 4This is a schematic cross-sectional view showing the magnetoresistive effect element 30, the in-plane magnetized film multilayer structure 32, and the hard bias layer 34 of the third embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetized film multilayer structure 32 of the third embodiment of the present invention is applied to the hard bias layer 34 of the magnetoresistive effect element 30.

[0134] Hereinafter, the in-plane magnetization film multilayer structure 32 of this third embodiment will be described, but for the same constituent elements as in the first embodiment, the same symbols will be used in principle, and the description will be omitted.

[0135] like Figure 4 As shown, the in-plane magnetized film multilayer structure 32 of the third embodiment of the present invention is formed as follows: an initial magnetic layer 32A is formed on the insulating layer 70; a first magnetic layer main body portion 32B is formed on the initial magnetic layer 32A; a non-magnetic intermediate layer 32D is formed on the first magnetic layer main body portion 32B; and a second magnetic layer main body portion 32C is formed on the non-magnetic intermediate layer 32D. The in-plane magnetized film multilayer structure 32 of the third embodiment of the present invention forms a structure in which the magnetic layer main body portion is separated into the first magnetic layer main body portion 32B and the second magnetic layer main body portion 32C by the non-magnetic intermediate layer 32D. Here, the composition and thickness of the initial magnetic layer 32A are the same as those of the initial magnetic layer 12A of the in-plane magnetized film 12 of the first embodiment, and therefore, description is omitted in principle. Furthermore, the composition of the first magnetic layer main body portion 32B and the second magnetic layer main body portion 32C are the same as those of the magnetic layer main body portion 12B of the in-plane magnetized film 12 of the first embodiment, and therefore, description is omitted in principle.

[0136] The in-plane magnetized film multilayer structure 32 of this third embodiment can be used as a hard bias layer 34 of the magnetoresistive effect element 30, and can apply a bias magnetic field to the free magnetic layer 60 that exerts the magnetoresistive effect.

[0137] The non-magnetic intermediate layer 32D separates the main body of the magnetic layer in the thickness direction, forming a first magnetic layer main body 32B and a second magnetic layer main body 32C, thus multiplying the magnetic layer. It is a layer that can further improve the coercivity Hc while maintaining the value of remanence Mrt per unit area by reducing the thickness of a single magnetic layer while maintaining the total thickness of the magnetic layers.

[0138] The first magnetic layer main body portion 32B and the second magnetic layer main body portion 32C, separated by the sandwiched non-magnetic intermediate layer 32D, are arranged in a spin-parallel (same direction) configuration. This configuration allows the first magnetic layer main body portion 32B and the second magnetic layer main body portion 32C, separated by the sandwiched non-magnetic intermediate layer 32D, to achieve ferromagnetic coupling. Therefore, the in-plane magnetized film multilayer structure 32 can improve the coercivity Hc while maintaining the remanence Mrt value per unit area, exhibiting excellent coercivity Hc.

[0139] Regarding the thickness of the first magnetic layer main body 32B and the second magnetic layer main body 32C, the total thickness can be considered. The total thickness of the first magnetic layer main body 32B and the second magnetic layer main body 32C is typically 15 nm or more and 80 nm or less. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, the total thickness of the first magnetic layer main body 32B and the second magnetic layer main body 32C is preferably 20 nm or more and 60 nm or less, and more preferably 25 nm or more and 50 nm or less.

[0140] From the viewpoint of not impairing the crystal structure of the CoPt alloy magnetic grains, the metal used in the non-magnetic intermediate layer 32D 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 32D, Ru or a Ru alloy with the same crystal structure (hexagonal close-packed structure hcp) as the CoPt alloy magnetic grains in the in-plane magnetization film 12 can be appropriately used.

[0141] When the metal used in the non-magnetic intermediate layer 32D is a Ru alloy, the added element can be, for example, Cr, Pt, or Co. The range of the amount of these metals added can be set to the range of the Ru alloy when it is a hexagonal close-packed structure (hcp).

[0142] 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 when the Cr content in the RuCr alloy was 50 atomic%, a mixed phase of hexagonal close-packed structure hcp and RuCr2 was identified. Therefore, when using the RuCr alloy as a non-magnetic interlayer 32D, setting the Cr content to less than 50 atomic% is appropriate, preferably less than 40 atomic%, and more preferably less than 30 atomic%. Furthermore, when the Pt content in the RuPt alloy was 15 atomic%, a mixed phase of hexagonal close-packed structure hcp and face-centered cubic structure fcc from Pt was identified. Therefore, when using the RuPt alloy as a non-magnetic interlayer 32D, setting the Pt content to less than 15 atomic% is appropriate, preferably less than 12.5 atomic%, and more preferably less than 10 atomic%. Furthermore, in RuCo alloys, a hexagonal close-packed structure (hcp) is formed regardless of the amount of Co added. However, when more than 40 atomic% of Co is added, it becomes a magnetic material. Therefore, it is appropriate to set the amount of Co added to less than 40 atomic%, preferably less than 30 atomic%, and more preferably less than 20 atomic%.

[0143] Regarding the thickness of the non-magnetic intermediate layer 32D, if the thickness of the non-magnetic intermediate layer 32D is too thin, it may not be able to perform the above-mentioned function (separating the main body of the magnetic layer in the thickness direction, separating it into a first magnetic layer main body 32B and a second magnetic layer main body 32C to form multiple layers, and further improving the coercivity Hc by reducing the thickness of a single magnetic layer while maintaining the total thickness of the magnetic layers). Therefore, the thickness of the non-magnetic intermediate layer 32D is typically 0.3 nm or more, preferably 0.5 nm or more, and more preferably 0.7 nm or more.

[0144] On the other hand, the thinner the non-magnetic intermediate layer 32D, the greater the proportion of in-plane magnetized films (initial magnetic layer 32A and magnetic layer main bodies 32B, 32C) in the in-plane magnetized film multilayer structure 32, and the greater the magnetic field applied by the hard bias layer 34 composed of the in-plane magnetized film multilayer structure 32 to the free magnetic layer 60. Therefore, the thickness of the non-magnetic intermediate layer 32D is typically 2 nm or less, preferably 1.5 nm or less, and more preferably 1.2 nm or less.

[0145] Therefore, the thickness of the non-magnetic intermediate layer 32D is typically 0.3 nm or more and 2 nm or less, preferably 0.5 nm or more and 1.5 nm or less, and more preferably 0.7 nm or more and 1.2 nm or less.

[0146] (4) Fourth implementation method

[0147] Figure 5 This is a schematic cross-sectional view showing the magnetoresistive effect element 40, the in-plane magnetized film multilayer structure 42, and the hard bias layer 44 of the fourth embodiment of the present invention. It is also a schematic cross-sectional view showing the state in which the in-plane magnetized film multilayer structure 42 of the fourth embodiment of the present invention is applied to the hard bias layer 44 of the magnetoresistive effect element 40.

[0148] Hereinafter, the in-plane magnetization film multilayer structure 42 of this fourth embodiment will be described, but for the same constituent elements as in the first embodiment, the same symbols will be used in principle, and the description will be omitted.

[0149] like Figure 5 As shown, the in-plane magnetized film multilayer structure 42 of the fourth embodiment of the present invention is formed as follows: an initial magnetic layer 42A is formed on the insulating layer 70, a non-magnetic initial intermediate layer 42D is formed on the initial magnetic layer 42A, a first magnetic layer main body portion 42B is formed on the non-magnetic initial intermediate layer 42D, a non-magnetic intermediate layer 42E is formed on the first magnetic layer main body portion 42B, and a second magnetic layer main body portion 42C is formed on the non-magnetic intermediate layer 42E. The initial magnetic layer 42A is separated from the magnetic layer main bodies 42B and 42C through the non-magnetic initial intermediate layer 42D. In addition, the in-plane magnetized film multilayer structure 42 of the fourth embodiment of the present invention forms a structure in which the magnetic layer main body portion is separated into the first magnetic layer main body portion 42B and the second magnetic layer main body portion 42C through the non-magnetic intermediate layer 42E. Here, the composition and thickness of the initial magnetic layer 42A, the first magnetic layer main body 42B, and the second magnetic layer main body 42C are the same as those of the initial magnetic layer 32A, the first magnetic layer main body 32B, and the second magnetic layer main body 32C of the in-plane magnetized film multilayer structure 32 of the third embodiment, so the description is omitted in principle.

[0150] The in-plane magnetized film multilayer structure 42 of this fourth embodiment can be used as a hard bias layer 44 of the magnetoresistive effect element 40, and can apply a bias magnetic field to the free magnetic layer 60 that exerts the magnetoresistive effect.

[0151] The non-magnetic initial intermediate layer 42D separates the initial magnetic layer 42A and the first magnetic layer main body 42B in the thickness direction to form multiple layers. It is a layer that has the function of further improving the coercivity Hc while maintaining the value of remanence Mrt per unit area by reducing the thickness of a single magnetic layer while maintaining the total thickness of the magnetic layers.

[0152] The initial magnetic layer 42A and the main body of the first magnetic layer 42B, separated by the non-magnetic initial intermediate layer 42D, are arranged with their spins parallel (in the same direction). This arrangement allows the initial magnetic layer 42A and the main body of the first magnetic layer 42B to achieve ferromagnetic coupling, thus enabling the in-plane magnetized film multilayer structure 42 to improve coercivity Hc while maintaining the remanence Mrt value per unit area, exhibiting excellent coercivity Hc.

[0153] The metal used in the non-magnetic initial intermediate layer 42D is the same as the metal used in the non-magnetic initial intermediate layer 22C of the in-plane magnetized film multilayer structure 22 in the second embodiment. In addition, the thickness of the non-magnetic initial intermediate layer 42D is the same as the thickness of the non-magnetic initial intermediate layer 22C of the in-plane magnetized film multilayer structure 22 in the second embodiment.

[0154] The non-magnetic intermediate layer 42E separates the main body of the magnetic layer in the thickness direction, forming a first magnetic layer main body 42B and a second magnetic layer main body 42C, thus multiplying the magnetic layer. It is a layer that has the function of further improving the coercivity Hc while maintaining the value of remanence Mrt per unit area by reducing the thickness of a single magnetic layer while maintaining the total thickness of the magnetic layers.

[0155] The first magnetic layer main body portion 42B and the second magnetic layer main body portion 42C, separated by the sandwiched non-magnetic intermediate layer 42E, are arranged in a spin-parallel (same direction) configuration. This configuration allows the first magnetic layer main body portion 42B and the second magnetic layer main body portion 42C, separated by the sandwiched non-magnetic intermediate layer 42E, to achieve ferromagnetic coupling. Therefore, the in-plane magnetized film multilayer structure 42 can improve the coercivity Hc while maintaining the remanence Mrt value per unit area, exhibiting excellent coercivity Hc.

[0156] The metal used in the non-magnetic intermediate layer 42E is the same as the metal used in the non-magnetic intermediate layer 32D of the in-plane magnetized film multilayer structure 32 of the third embodiment. In addition, the thickness of the non-magnetic intermediate layer 42E is the same as the thickness of the non-magnetic intermediate layer 32D of the in-plane magnetized film multilayer structure 32 of the third embodiment.

[0157] Example

[0158] Hereinafter, embodiments, comparative examples, and reference examples used to demonstrate the present invention will be described.

[0159] In (A) below, the influence of the type of nonmagnetic grain boundary oxide in the initial magnetic layer of the in-plane magnetized film in a CoPt-nonmagnetic oxide monolayer structure on the coercivity Hc and the remanence Mrt per unit area was studied; in (B) below, the influence of the thickness of the initial magnetic layer of the in-plane magnetized film on the coercivity Hc in a CoPt-nonmagnetic oxide multilayer structure (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) on the coercivity Hc. The effects of remanence Mrt per unit area were studied; in (C) below, the effects of oxide (ZnO) content (volume fraction) in the initial magnetic layer of the in-plane magnetized film in a CoPt-nonmagnetic oxide multilayer structure (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) on coercivity Hc and remanence Mrt per unit area were studied; in (D) below, the effects of remanence Mrt on the remanence of CoPt-nonmagnetic oxide multilayer structure were studied. The influence of the metal composition ratio of Co and Pt in the initial magnetic layer of the in-plane magnetized film in a multi-layer structure of CoPt-nonmagnetic oxide (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) on the coercivity Hc and remanence Mrt per unit area was studied. In (E) below, the effect of the in-plane magnetization ratio on the coercivity Hc and remanence Mrt per unit area in a multi-layer structure of CoPt-nonmagnetic oxide (initial magnetic layer: CoPt in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) was studied. The effects of Ta2O5, the nonmagnetic grain boundary material of the initial magnetic layer of the magnetized film, on the coercivity Hc and remanence Mrt per unit area were investigated. In (F) below, the effects of adding Fe as the metal component in the initial magnetic layer of the in-plane magnetized film of a CoPt-nonmagnetic oxide multilayer structure (initial magnetic layer: CoPt-ZnO in-plane magnetized film, magnetic layer body: CoPt-B2O3 in-plane magnetized film) on the coercivity Hc and remanence Mrt per unit area were investigated.

[0160] The actual composition (obtained through compositional analysis) of the fabricated CoPt-nonmagnetic oxide in-plane magnetization film deviates from the composition of the sputtering target used in fabricating the CoPt-nonmagnetic oxide in-plane magnetization film. Therefore, for multiple points in the fabricated CoPt-nonmagnetic oxide in-plane magnetization film, the actual composition is obtained through compositional analysis. Based on this result, calculations to correct the compositional deviation are performed in all the embodiments, comparative examples, and reference examples described below, and the corrected composition is used as the composition of the in-plane magnetization film of each embodiment, comparative example, and reference example.

[0161] In the compositional analysis of the in-plane magnetized film, energy-dispersive X-ray diffraction (EDX) was used as the elemental analysis method, and the EMAXEvolution instrument manufactured by Horiba Manufacturing Co., Ltd. was used as the elemental analysis apparatus. However, boron (B) is a light element with a lower atomic number than oxygen (O), and therefore cannot be detected by EDX analysis. Thus, the accurate value of the B2O3 content in the in-plane magnetized film is currently unknown. Therefore, although the values ​​of B2O3 content in the composition of the in-plane magnetized films described in the following examples, comparative examples, and reference examples represent the B2O3 content in the target composition, these values ​​may deviate from the actual values.

[0162] The compositions of the CoPt-nonmagnetic oxide in-plane magnetized films in the Examples, Comparative Examples, and Reference Examples described in (A) to (F) below were calculated by performing calculations to correct for compositional deviations based on the composition of the sputtering target used in the fabrication. However, for B2O3, as described above, the value of the B2O3 content in the target composition is described.

[0163] <(A) The influence of the type of nonmagnetic oxide in the initial magnetic layer of the in-plane magnetized film on the coercivity Hc and remanence Mrt per unit area in a CoPt-nonmagnetic oxide monolayer structure (refer to Examples 1-8)>

[0164] In Reference Examples 1-8, various changes were made to the type of nonmagnetic grain boundary oxide in the in-plane magnetization film monolayer structure of CoPt-nonmagnetic oxide formed on a silicon substrate, and experimental data were obtained. The nonmagnetic grain boundary oxides used in Reference Examples 1-8, in the order from Reference Example 1 to Reference Example 8, were Al2O3, B2O3, Ga2O3, MgO, MnO, Nb2O5, Ta2O5, and ZnO. The in-plane magnetization films of the formed CoPt-nonmagnetic oxide were all monolayers, without any nonmagnetic intermediate layers.

[0165] The silicon substrate used underwent an oxidation treatment of approximately 100 nm, resulting in silicon oxide (SiOx) serving as an insulating layer. Furthermore, the surface of the silicon substrate was mirror-finished, achieving a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. That is, the surface roughness Ra (arithmetic mean roughness) of the silicon oxide (SiOx) forming the substrate layer of the in-plane magnetization film (the silicon oxide (SiOx) serving as the insulating layer on the surface of the silicon substrate) is 0.1 nm. Hereinafter, this silicon substrate will be referred to as the surface-oxidized silicon substrate.

[0166] Using an ES-3100W sputtering apparatus manufactured by Eco Engineering Co., Ltd., in-plane magnetized monolayer structures of CoPt-nonmagnetic oxides, each with a thickness of 15 nm, were formed on a surface-oxidized silicon substrate in Reference Examples 1-8. No substrate heating was performed during this film formation process; film formation was carried out at room temperature. It should be noted that in the embodiments, comparative examples, and reference examples of this application, the sputtering apparatus used for sample fabrication was the ES-3100W manufactured by Eco Engineering Co., Ltd. in all film formation processes; the apparatus name will be omitted hereinafter.

[0167] Specifically, as described below, the preparation of samples and the acquisition of experimental data are used to study the types of nonmagnetic grain boundary oxides in the initial magnetic layer.

[0168] In Reference Example 1, a (Co-25Pt)-10 vol% Al2O3 sputtering target was used to form a 15 nm thick (Co-26.12Pt)-5.11 vol% Al2O3 in-plane magnetization film monolayer structure on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate, by sputtering. In Reference Example 2, a (Co-25Pt)-10 vol% B2O3 sputtering target was used to form a (Co-25Pt)-10 vol% B2O3 sputtering target on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate, by sputtering. A 15 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film monolayer structure was formed. In Reference Example 3, a (Co-25Pt)-10 vol% Ga2O3 sputtering target was used to form a 15 nm thick (Co-26.12Pt)-4.89 vol% Ga2O3 in-plane magnetization film monolayer structure on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the substrate insulating layer, by sputtering. In Reference Example 4, a (Co-25Pt)-10 vol% MgO sputtering target was used to form a 15 nm thick (Co-26.12Pt)-4.89 vol% Ga2O3 in-plane magnetization film monolayer structure on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. A 15 nm thick monolayer structure of (Co-26.12Pt)-4.28 vol% MgO in-plane magnetization film was formed by sputtering on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Reference Example 5, a (Co-25Pt)-10 vol% MnO sputtering target was used to form a 15 nm thick monolayer structure of (Co-26.12Pt)-4.72 vol% MnO in-plane magnetization film on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Reference Example 6, a (Co-25Pt)-10 vol% MnO sputtering target was used. A 15 nm thick (Co-26.12Pt)-4.57 vol% Nb2O5 in-plane magnetization film monolayer structure was formed by sputtering on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Reference Example 7, a (Co-25Pt)-10 vol% Ta2O5 sputtering target was used to form a 15 nm thick (Co-26.12Pt)-4.57 vol% Nb2O5 in-plane magnetization film monolayer structure by sputtering on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate.A 32 vol% Ta₂O₅ in-plane magnetized monolayer structure; In Reference Example 8, using a (Co-25Pt)-10 vol% ZnO sputtering target, a 15 nm thick (Co-26.12Pt)-4.44 vol% ZnO in-plane magnetized monolayer structure was formed by sputtering on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate.

[0169] On the in-plane magnetized film monolayer structure of Reference Examples 1 to 8 formed as described above, a carbon capping layer was formed by sputtering to prepare samples for measuring magnetic properties.

[0170] In all the film formation processes described in Reference Examples 1 to 8, no substrate heating was performed, and film formation was carried out at room temperature.

[0171] The hysteresis loops of the monolayer structures of the in-plane magnetized films (initial magnetic layers) of Reference Examples 1-8 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 ) and saturation magnetization Ms (memu / cm) 3 Then, make the read remanence Mr (memu / cm) 3 Multiplying this by the thickness of the fabricated CoPt in-plane magnetization film (initial magnetic layer), the remanence per unit area (Mrt / cm²) of the fabricated in-plane magnetization film (initial magnetic layer) monolayer structure is calculated. 2 ), making the read saturated magnetization Ms (memu / cm) 3 Multiplying this by the thickness of the fabricated CoPt in-plane magnetization film (initial magnetic layer), the saturation magnetization Mst (memu / cm²) per unit area of ​​the fabricated in-plane magnetization film (initial magnetic layer) monolayer structure is calculated. 2 ).

[0172] The experimental results of Reference Examples 1 to 8 are shown in Table 1 below. Furthermore, for the experimental results of Reference Examples 1 to 8, a bar chart is presented with the type of nonmagnetic grain boundary oxide as the horizontal axis and the coercivity Hc(kOe) as the vertical axis. Figure 6 middle.

[0173] Furthermore, for the CoPt in-plane magnetization film (initial magnetic layer) of Reference Example 8 with a composition of (Co-26.12Pt)-4.44 vol% ZnO, its vertical cross-section (the cross-section of the CoPt in-plane magnetization film in a direction orthogonal to the in-plane direction) was observed using a scanning transmission electron microscope (H-9500 manufactured by Hitachi High-Tech Co., Ltd.), and observation images (cross-sectional TEM photographs) were obtained. These observation images (cross-sectional TEM photographs) are shown below. Figure 7 middle.

[0174] [Table 1]

[0175]

[0176] From Table 1 and Figure 6 It can be seen that the coercivity Hc of Reference Example 7, which uses Ta2O5 as the non-magnetic grain boundary oxide for in-plane magnetization film (initial magnetic layer), and Reference Example 8, which uses ZnO as the non-magnetic grain boundary oxide for in-plane magnetization film (initial magnetic layer), are 2.09 kOe and 3.13 kOe, respectively, which exceed 2.00 kOe. Compared with Reference Examples 1 to 6, which use other non-magnetic grain boundary oxides, exceptionally good coercivity Hc can be obtained.

[0177] The excellent coercivity Hc observed in Reference Examples 7 and 8 was obtained by directly forming an in-plane magnetization film (initial magnetic layer) on an extremely smooth silicon oxide layer (the surface oxide treatment layer of the surface-oxidized silicon substrate, i.e., the insulating layer that becomes the base layer) with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. This is a groundbreaking result. Figure 7As shown in the cross-sectional TEM images, the initial magnetic layer of (Co-26.12Pt)-4.44 vol% ZnO in Reference Example 8, although formed directly on an extremely smooth silicon oxide layer (the surface oxide treatment layer of the surface-oxidized silicon substrate, i.e., the insulating layer that becomes the base layer) with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, exhibits clearly separated columnar Co-26.12Pt alloy particles. For the initial magnetic layer of (Co-26.12Pt)-4.32 vol% Ta₂O₅ in Reference Example 7, its vertical cross-section was not observed using an electron microscope at this stage. However, although the coercivity Hc (2.09 kOe) of Reference Example 7 exceeds 2.00 kOe, it is less than that of Reference Example 8 (3.13 kOe). Therefore, it is considered that the initial magnetic layer of Reference Example 7 does not exhibit the clearly separated columnar Co-26.12Pt alloy particles as seen in the initial magnetic layer of Reference Example 8. For the initial magnetic layers of Reference Examples 1 to 6, their vertical cross-sections were not observed using an electron microscope at this stage. However, the coercivity Hc of Reference Examples 1 to 6 was 0.14 kOe to 1.21 kOe, which was not good. Therefore, in the initial magnetic layers of Reference Examples 1 to 6, it is believed that, as previously thought, the CoPt alloy particles were almost not formed in a columnar shape on the amorphous silicon oxide layer (the surface oxide treatment layer of the surface-oxidized silicon substrate, i.e., the insulating layer that becomes the base layer), and the magnetic separation of the CoPt alloy particles was poor.

[0178] As described above, in the prior art, a non-magnetic substrate layer (Cr, Ti, Cr alloy, Ti alloy, etc.) is used as the substrate layer for the Co-Pt-based in-plane magnetization film to promote the in-plane orientation of the c-axis of the CoPt alloy with the hcp structure (paragraph 0028 of Patent Document 2 described in the [Prior Art Documents] section). Furthermore, as described above, in other prior art, a non-magnetic Ru substrate layer is formed by applying a high gas pressure during film formation, and a Co-Pt-based in-plane magnetization film is formed on this non-magnetic Ru substrate layer with a thickness of approximately 15 nm or more, thereby increasing the coercivity Hc of the Co-Pt-based in-plane magnetization film (paragraph 0016 of Patent Document 3 described in the [Prior Art Documents] section, and Non-Patent Document 1). In the existing technology, it is impossible to directly form an in-plane magnetization film on an extremely smooth silicon oxide layer (the surface oxide treatment layer of the surface-oxidized silicon substrate, which is the insulating layer that becomes the base layer) with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm to obtain good coercivity Hc, etc.

[0179] Based on the experimental results of coercivity Hc for Reference Examples 7 and 8, in this invention, a nonmagnetic grain boundary oxide containing at least one of Zn oxide and Ta oxide is used as the nonmagnetic grain boundary oxide for the in-plane magnetization film (initial magnetic layer) formed directly on a substrate with an extremely smooth silicon oxide layer (surface oxide treatment layer of surface oxide treated silicon substrate, i.e., insulating layer that becomes the base layer) having a surface roughness Ra (arithmetic mean roughness) of 0.1 nm.

[0180] In the studies (B) to (D) and (F) below, the in-plane magnetization film (using ZnO as a non-magnetic grain boundary oxide) of Reference Example 8, which yielded the best results, was used as the initial magnetic layer.

[0181] It should be noted that, as Figure 7 As shown in the cross-sectional TEM image, the initial magnetic layer of (Co-26.12Pt)-4.44 vol% ZnO in Reference Example 8 is a granular structure formed by clearly separated columnar Co-26.12Pt alloy particles. Considering that the (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film used as the main body of the magnetic layer in the studies below (B) to (F) also has the same granular structure, it is believed that the insights from the experimental data on the content of nonmagnetic grain boundary materials (oxides) and the composition of the metal components (Co, Pt, Fe) of the CoPt-ZnO in-plane magnetization film (initial magnetic layer) can also be applied to the study of the numerical range of the content of nonmagnetic grain boundary materials (oxides) and the numerical range of the composition of the metal components (Co, Pt, Fe) in the main body of the magnetic layer.

[0182] <(B) Study on the influence of the thickness of the initial magnetic layer of the in-plane magnetized film on the coercivity Hc and remanence Mrt per unit area in a multilayer structure of CoPt-nonmagnetic oxide in-plane magnetized film (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main body of magnetic layer: CoPt-B2O3 in-plane magnetized film) (Examples 1-6, Comparative Example 1)>

[0183] In Examples 1 to 6, on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which is the insulating layer that serves as the base layer, a (Co-25Pt)-10 vol% ZnO sputtering target was used to form an in-plane magnetization film of (Co-26.12Pt)-4.44 vol% ZnO as the initial magnetic layer by sputtering. The thickness was changed to 2 nm (Example 1), 5 nm (Example 2), 10 nm (Example 3), 15 nm (Example 4), 20 nm (Example 5), and 30 nm (Example 6).

[0184] Then, on the formed (Co-26.12Pt)-4.44 vol% ZnO in-plane magnetization film (initial magnetic layer), a Ru non-magnetic initial intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic initial intermediate layer with a thickness of 1 nm, an (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film with a thickness of 15 nm, serving as the main body of the first magnetic layer, is formed by sputtering. On the formed (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film with a thickness of 15 nm, serving as the main body of the first magnetic layer, a Ru non-magnetic intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic intermediate layer with a thickness of 1 nm, an (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film with a thickness of 15 nm, serving as the main body of the second magnetic layer, is formed by sputtering, thereby forming a multilayer structure of in-plane magnetization films.

[0185] In Comparative Example 1, no (Co-26.12Pt)-4.44 vol% ZnO in-plane magnetization film as the initial magnetic layer was formed on the surface-oxidized silicon substrate. Instead, an in-plane (Co-26.12Pt)-10 vol% B2O3 in-plane magnetization film with a thickness of 15 nm was formed on the surface-oxidized silicon substrate, that is, on the extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and the base layer, by sputtering. A magnetized film is formed by sputtering a 1 nm thick Ru non-magnetic intermediate layer on a (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which serves as the main body of the first magnetic layer, and then sputtering a 15 nm thick (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film, which serves as the main body of the second magnetic layer, on the 1 nm thick Ru non-magnetic intermediate layer, thereby forming a multilayer structure of in-plane magnetized film.

[0186] On the in-plane magnetized film multilayer structures of Examples 1 to 6 and Comparative Example 1 formed as described above, carbon capping layers were formed by sputtering to prepare samples for magnetic property measurement.

[0187] In all the film formation processes described in Examples 1-6 and Comparative Example 1, no substrate heating was performed, and film formation was carried out at room temperature.

[0188] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 1-6 were measured using a vibrating magnetometer. The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loops. 3 ) and saturation magnetization Ms (memu / cm) 3 Then, make the read remanence Mr (memu / cm) 3Multiplying 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 ), making the read saturated magnetization Ms (memu / cm) 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film, the saturation magnetization Mst (memu / cm) per unit area of ​​the fabricated in-plane magnetized multilayer structure is calculated. 2 ).

[0189] The experimental results of Examples 1-6 and Comparative Example 1 are shown in Table 2 below. Furthermore, for the experimental results of Examples 1-6 and Comparative Example 1, a graph is plotted with the initial magnetic layer thickness of the in-plane magnetization film as the horizontal axis and the coercivity Hc(kOe) as the vertical axis. Figure 8 middle.

[0190] [Table 2]

[0191]

[0192] From Table 2 and Figure 8 It is known that when the initial magnetic layer thickness using ZnO as the non-magnetic oxide grain boundary material is 15 nm (Example 4), the coercivity Hc is 3.15 kOe, which is the maximum. However, if the initial magnetic layer thickness using ZnO as the non-magnetic oxide grain boundary material is thicker than 15 nm, the coercivity Hc decreases when the thickness reaches 20 nm (Example 5) or 30 nm (Example 6). Therefore, the initial magnetic layer using ZnO as the non-magnetic oxide grain boundary material is only used in a limited range from the surface of the surface-oxidized silicon substrate (for example, within about 30 nm from the surface of the surface-oxidized silicon substrate) as the main body of the magnetic layer. It is considered preferable to use an in-plane magnetization film (CoPt-B2O3) that uses B2O3 as the non-magnetic oxide grain boundary material, which has been conventionally used as an in-plane magnetization film.

[0193] From Table 2 and Figure 8 The results show that the multilayer structure of the in-plane magnetized film exhibits excellent magnetic properties (coercivity Hc above 2.00 kOe, remanence per unit area of ​​2.00 memu / cm). 2 Based on the above viewpoints, the thickness of the initial magnetic layer is generally 1 nm or more and 32 nm or less. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, the thickness of the initial magnetic layer is preferably 2 nm or more and 30 nm or less, and more preferably 8 nm or more and 20 nm or less.

[0194] In Comparative Example 1, no initial magnetic layer using ZnO as a non-magnetic oxide grain boundary material was provided. Instead, an in-plane magnetization film (CoPt-B2O3) using B2O3 as a non-magnetic oxide grain boundary material was directly formed on a surface-oxidized silicon substrate, which is not included in the scope of this invention. In Comparative Example 1, although the coercivity Hc was 2.48 kOe, exceeding 2.00 kOe, the remanence Mrt per unit area was 1.83 memu / cm. 2 The result showed that the remanence Mrt per unit area was less than 2.00 memu / cm. 2 .

[0195] <(C) Study on the effect of oxide (ZnO) content (volume fraction) in the initial magnetic layer of the in-plane magnetized film on coercivity Hc and remanence Mrt per unit area in a multilayer structure of CoPt-nonmagnetic oxide in-plane magnetized film (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) (Examples 4, 7-15, Comparative Examples 2, 3)>

[0196] In Examples 4, 7-15, and Comparative Examples 2 and 3, on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which is an insulating layer that serves as the base layer, the ZnO content was varied from 0 vol% to 30.10 vol% to form an initial magnetic layer containing CoPt with a thickness of 15 nm by sputtering.

[0197] Specifically, in Comparative Example 2, a Co-25Pt sputtering target without non-magnetic oxide grain boundary materials was used to form a 15nm thick Co-26.12Pt initial magnetic layer on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1nm, which serves as the insulating layer and acts as the base layer, by sputtering. In Comparative Example 3, a (Co-25Pt)-4 vol% ZnO sputtering target was used to form a 1nm thick Co-26.12Pt initial magnetic layer on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1nm, which serves as the insulating layer and acts as the base layer, by sputtering. A 5 nm (Co-26.12Pt)-1.60 vol% ZnO initial magnetic layer; In Example 7, using a (Co-25Pt)-6 vol% ZnO sputtering target, a 15 nm thick (Co-26.12Pt)-2.30 vol% ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate; In Example 8, using a (Co-25Pt)-8 vol% ZnO sputtering target, a 5 nm thick (Co-26.12Pt)-1.60 vol% ZnO initial magnetic layer was formed on a surface-oxidized silicon substrate, i.e., on an insulating layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 4, an initial magnetic layer of (Co-26.12Pt)-3.25 vol% ZnO with a thickness of 15 nm was formed by sputtering on an extremely smooth silicon oxide layer of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Example 9, an initial magnetic layer of (Co-26.12Pt)-4.44 vol% ZnO with a thickness of 15 nm was formed by sputtering on an oxide-treated silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Example 9, an initial magnetic layer of (Co-26.12Pt)-4.25 vol% ZnO with a thickness of 15 nm was formed by sputtering on an extremely smooth silicon oxide layer of 0.1 nm, which serves as the insulating layer and acts as the substrate. On a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm (which serves as the insulating layer and acts as the base layer), a 15 nm thick (Co-26.12Pt)-5.89 vol% ZnO initial magnetic layer is formed by sputtering. In Example 10, a (Co-25Pt)-14 vol% ZnO sputtering target is used to form a 15 nm thick (Co-26.12Pt)-7 layer on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm (which serves as the insulating layer and acts as the base layer).A 58 vol% ZnO initial magnetic layer; In Example 11, using a (Co-25Pt)-16 vol% ZnO sputtering target, a 15 nm thick (Co-26.12Pt)-9.53 vol% ZnO initial magnetic layer was formed by sputtering on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and forms the substrate; In Example 12, using a (Co-25Pt)-18 vol% ZnO target, a 58 vol% ZnO initial magnetic layer was formed by sputtering. A 15 nm thick (Co-26.12Pt)-11.72 vol% ZnO initial magnetic layer is formed by sputtering on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Example 13, a (Co-25Pt)-20 vol% ZnO sputtering target is used on a surface-oxidized silicon substrate, specifically on an insulating layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. In Example 14, an initial magnetic layer of (Co-26.12Pt)-14.16 vol% ZnO with a thickness of 15 nm was formed by sputtering on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. In Example 15, a (Co-25Pt)-25 vol% ZnO sputtering target was used to form a magnetic layer of (Co-25Pt)-25 vol% ZnO on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate. An initial magnetic layer of (Co-26.12Pt)-21.35 vol% ZnO with a thickness of 15 nm was formed. In Example 15, an initial magnetic layer of (Co-26.12Pt)-30 vol% ZnO with a thickness of 15 nm was formed by sputtering on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and forms the substrate.

[0198] Then, on the formed initial magnetic layer, a Ru non-magnetic initial intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic initial intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the first magnetic layer, is formed by sputtering. On the formed (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film of 15 nm, serving as the main body of the first magnetic layer, a Ru non-magnetic intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the second magnetic layer, is formed by sputtering, thereby forming a multilayer structure of in-plane magnetized film.

[0199] On the in-plane magnetized film multilayer structures of Examples 4, 7-15 and Comparative Examples 2 and 3 formed as described above, carbon capping layers were formed by sputtering to prepare samples for magnetic property measurement.

[0200] In all the film formation processes described in Examples 4, 7-15, and Comparative Examples 2 and 3, no substrate heating was performed, and film formation was carried out at room temperature.

[0201] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 4, 7-15, and Comparative Examples 2 and 3 were measured using a vibrating magnetometer. The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loops. 3 ) and saturation magnetization Ms (memu / cm) 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 ), making the read saturated magnetization Ms (memu / cm) 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film, the saturation magnetization Mst (memu / cm) per unit area of ​​the fabricated in-plane magnetized multilayer structure is calculated. 2 ).

[0202] The experimental results of Examples 4, 7-15, and Comparative Examples 2 and 3 are shown in Table 3 below. Furthermore, for the experimental results of Examples 4, 7-15, and Comparative Examples 2 and 3, a graph is plotted with the ZnO content in the initial magnetic layer of the in-plane magnetized film as the horizontal axis and the coercivity Hc(kOe) as the vertical axis. Figure 9 middle.

[0203] [Table 3]

[0204]

[0205] From Table 3 and Figure 9 It can be seen that when the ZnO content in the initial magnetic layer, using ZnO as a non-magnetic oxide grain boundary material, is 5.89 vol% (Example 9), the coercivity Hc is 3.25 kOe, which is the maximum. If the ZnO content in the initial magnetic layer, using ZnO as a non-magnetic oxide grain boundary material, is greater than 5.89 vol%, the larger the ZnO content in the initial magnetic layer, the smaller the coercivity Hc becomes. However, even if the ZnO content in the initial magnetic layer is as high as 30.10 vol%, the coercivity Hc is still 2.10 kOe, and the coercivity Hc remains above 2.00 kOe. Furthermore, Comparative Example 3, with an initial ZnO content of 1.60 vol%, had a coercivity Hc of 0.84 kOe. In contrast, Example 7, with an initial ZnO content of 2.30 vol%, had a coercivity Hc that increased sharply to 2.97 kOe. This indicates that if the ZnO content in the initial magnetic layer changes from 1.60 vol% to 2.30 vol%, the coercivity Hc of the in-plane magnetized film multilayer structure increases sharply.

[0206] From Table 3 and Figure 9 The results show that the multilayer structure of the in-plane magnetized film exhibits excellent magnetic properties (coercivity Hc above 2.00 kOe, remanence per unit area of ​​2.00 memu / cm). 2 Based on the above viewpoint, the ZnO content in the initial magnetic layer is set to be 2.0% or more and 31.0% or less relative to the overall volume of the initial magnetic layer. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, it is preferable to set it to 3.0% or more and 15.0% or less, and more preferably to set it to 4.0% or more and 10.0% or less.

[0207] The ZnO content in the initial magnetic layer was 0 vol% and 1.60 vol%, respectively. In Comparative Examples 2 and 3, which are outside the scope of the present invention, the ZnO content in the initial magnetic layer was less than 2.0 vol%. The coercivity was as low as 0.41 kOe and 0.84 kOe, respectively, and less than 2.00 kOe.

[0208] Regarding the remanence Mrt per unit area, it exceeded 3.00 memu / cm in Examples 4, 7-15, and Comparative Examples 2 and 3. 2 This is a good result.

[0209] <(D) Study on the influence of the metal composition ratio of Co and Pt in the initial magnetic layer of the in-plane magnetized film on the coercivity Hc and remanence Mrt per unit area in a multilayer structure of CoPt-nonmagnetic oxide in-plane magnetized film (initial magnetic layer: CoPt-ZnO in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) (Examples 4, 16-19, Comparative Examples 4, 5)>

[0210] In Examples 4, 16-19, and Comparative Examples 4 and 5, on a surface-oxidized silicon substrate, specifically on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the base layer, the composition of the metal components of the initial magnetic layer, namely Co and Pt, was varied. An initial magnetic layer (CoPt-ZnO) with a thickness of 15 nm was formed using ZnO as a non-magnetic oxide grain boundary material by sputtering. Specifically, relative to the total metal components of the initial magnetic layer, namely Co and Pt, Co was varied from 83.97 atomic percent to 31.04 atomic percent, and Pt was varied from 16.03 atomic percent to 68.96 atomic percent, obtaining experimental data.

[0211] In Comparative Example 4, a (Co-15Pt)-10 vol% ZnO sputtering target was used to form a 15 nm thick (Co-16.03Pt)-4.44 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the base layer, by sputtering. In Example 16, a (Co-20Pt)-10 vol% ZnO sputtering target was used to form a 15 nm thick (Co-16.03Pt)-4.44 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the base layer, by sputtering. A 15 nm thick (Co-20.13Pt)-4.44 vol% ZnO initial magnetic layer was formed; in Example 4, a (Co-25Pt)-10 vol% ZnO sputtering target was used to form a 15 nm thick (Co-26.12Pt)-4.44 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate, by sputtering; in Example 17, a (Co-30Pt)-10 vol% ZnO sputtering target was used to form a 15 nm thick (Co-20.13Pt)-4.44 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, i.e., on a surface-oxidized silicon substrate with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm. On an extremely smooth silicon oxide layer of nm, which serves as the insulating layer and acts as the substrate, a 15 nm thick (Co-34.00Pt)-4.44 vol% ZnO initial magnetic layer is formed by sputtering. In Example 18, a (Co-35Pt)-10 vol% ZnO sputtering target is used to form a 15 nm thick (Co-43.77Pt)-4.44 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, i.e., on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the substrate, by sputtering. In Example 19, a (Co-40Pt)-10 vol% ZnO sputtering target is used to form a (Co-40Pt)-10 vol% ZnO initial magnetic layer. On a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the base layer, a 15 nm thick (Co-55.42Pt)-4.44 vol% ZnO initial magnetic layer is formed by sputtering. In Comparative Example 5, a (Co-45Pt)-10 vol% ZnO sputtering target is used to form a 15 nm thick (Co-68.96Pt)-4.44 vol% ZnO initial magnetic layer on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and acts as the base layer, an initial magnetic layer is formed by sputtering.

[0212] Then, on the formed initial magnetic layer, a Ru non-magnetic initial intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic initial intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the first magnetic layer, is formed by sputtering. On the formed (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film of 15 nm, serving as the main body of the first magnetic layer, a Ru non-magnetic intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the second magnetic layer, is formed by sputtering, thereby forming a multilayer structure of in-plane magnetized film.

[0213] On the in-plane magnetized film multilayer structures of Examples 4, 16-19 and Comparative Examples 4 and 5 formed as described above, carbon capping layers were formed by sputtering to prepare samples for magnetic property measurement.

[0214] In all the film formation processes described in Examples 4, 16-19, and Comparative Examples 4 and 5, no substrate heating was performed, and film formation was carried out at room temperature.

[0215] The hysteresis loops of the in-plane magnetized film multilayer structures of Examples 4, 16-19, and Comparative Examples 4 and 5 were measured using a vibrating magnetometer. The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loops. 3 ) and saturation magnetization Ms (memu / cm) 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 ), making the read saturated magnetization Ms (memu / cm) 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film, the saturation magnetization Mst (memu / cm) per unit area of ​​the fabricated in-plane magnetized multilayer structure is calculated. 2 ).

[0216] The experimental results of Examples 4, 16-19, and Comparative Examples 4 and 5 are shown in Table 4 below. Additionally, a graph is plotted with the content of Pt (atomic %) of the initial magnetic layer relative to the total metal composition (Co and Pt) on the horizontal axis and the coercivity Hc (kOe) on the vertical axis. Figure 10 middle.

[0217] [Table 4]

[0218]

[0219] From Table 4 and Figure 10 It is known that, relative to the initial magnetic layer (in-plane magnetization film) of CoPt-ZnO, the total Co content is 44 atomic% or more and 82 atomic% or less, the Pt content is 18 atomic% or more and 56 atomic% or less, the volume ratio of ZnO to the overall in-plane magnetization film of CoPt-ZnO is 4.44 volume%, and the thickness is 15 nm. Examples 4, 16 to 19, which are included within the scope of the present invention, achieved a coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm² per unit area by room temperature film formation without substrate heating. 2 The above magnetic properties.

[0220] From Table 4 and Figure 10 The results show that the multilayer structure of the in-plane magnetized film exhibits excellent magnetic properties (coercivity Hc above 2.00 kOe, remanence per unit area of ​​2.00 memu / cm). 2 Based on the above viewpoints, the Pt content in the initial magnetic layer is set to be 18 atomic% or more and 56 atomic% or less relative to the total metal composition of the initial magnetic layer. From the perspective of balancing both coercivity Hc and remanence per unit area Mrt, it is preferably 20 atomic% or more and 45 atomic% or less relative to the total metal composition of the initial magnetic layer, more preferably 25 atomic% or more and 35 atomic% or less. Regarding the Co content in the initial magnetic layer, it is designed to ensure that the multilayer structure of the in-plane magnetized film exhibits good magnetic properties (coercivity Hc of 2.00 kOe or more, remanence per unit area of ​​2.00 memu / cm²). 2 Based on the above viewpoint, the Co content in the initial magnetic layer is set to be 44 atomic% or more and 82 atomic% or less relative to the total metal composition of the initial magnetic layer. From the viewpoint of balancing both coercivity Hc and remanence per unit area Mrt, it is preferable to be 55 atomic% or more and 80 atomic% or less relative to the total metal composition of the initial magnetic layer, and more preferably 65 atomic% or more and 75 atomic% or less.

[0221] On the other hand, in Comparative Example 4, which is not included in the scope of this invention and has a Co content of 83.97 atomic% and a Pt content of 16.03 atomic% relative to the total metal composition (Co, Pt) of the initial magnetic layer (in-plane magnetization film) of CoPt-ZnO, the coercivity Hc is 1.68 kOe, which is less than 2.00 kOe. Furthermore, in Comparative Example 5, which is not included in the scope of this invention and has a Co content of 31.04 atomic% and a Pt content of 68.96 atomic% relative to the total metal composition (Co, Pt) of the initial magnetic layer (in-plane magnetization film) of CoPt-ZnO, the coercivity Hc is 1.55 kOe, which is less than 2.00 kOe, and the remanence Mrt per unit area is 1.79 memu / cm². 2 The remanence per unit area, Mrt, is less than 2.00 memu / cm. 2 .

[0222] <(E) Study on the effect of using Ta2O5 as the nonmagnetic grain boundary material of the initial magnetic layer of the in-plane magnetized film in a multilayer structure of CoPt-nonmagnetic oxide in-plane magnetized film (initial magnetic layer: CoPt in-plane magnetized film, main magnetic layer: CoPt-B2O3 in-plane magnetized film) on coercivity Hc and remanence Mrt per unit area (Examples 4, 20)>

[0223] In Example 20, an initial magnetic layer with Ta2O5 as the non-magnetic grain boundary material was formed by sputtering to prepare a sample for magnetic property measurement and obtain experimental data.

[0224] Specifically, using a (Co-25Pt)-10 vol% Ta2O5 sputtering target, an initial magnetic layer of (Co-26.12Pt)-4.32 vol% Ta2O5 with a thickness of 15 nm is formed on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer of the substrate, by sputtering.

[0225] Then, on the formed initial magnetic layer, a Ru non-magnetic initial intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic initial intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the first magnetic layer, is formed by sputtering. On the formed (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film of 15 nm, serving as the main body of the first magnetic layer, a Ru non-magnetic intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the second magnetic layer, is formed by sputtering, thereby forming a multilayer structure of in-plane magnetized film.

[0226] On the in-plane magnetized film multilayer structure of Example 20 formed as described above, a carbon capping layer is formed by sputtering to prepare a sample for measuring magnetic properties.

[0227] In all the film formation processes described in Example 20, no substrate heating was performed, and film formation was carried out at room temperature.

[0228] The hysteresis loop of the in-plane magnetized film multilayer structure of Example 20 was measured using a vibrating magnetometer. The coercivity Hc (kOe) and remanence Mr (memu / cm²) were read from the measured hysteresis loop. 3 ) and saturation magnetization Ms (memu / cm) 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 ), making the read saturated magnetization Ms (memu / cm) 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film, the saturation magnetization Mst (memu / cm) per unit area of ​​the fabricated in-plane magnetized multilayer structure is calculated. 2 ).

[0229] The experimental results of Example 20 are presented together with those of Example 4 in Table 5 below.

[0230] [Table 5]

[0231]

[0232] As shown in Table 5, in Example 20 where the nonmagnetic grain boundary material of the initial magnetic layer is Ta2O5, a coercivity Hc of 3.01 kOe and a remanence Mrt of 3.16 memu / cm per unit area can also be obtained.2 The magnetic properties are good. However, in Example 4, where the nonmagnetic grain boundary material of the initial magnetic layer is ZnO, the coercivity Hc and the remanence Mrt per unit area are better than in Example 20, where the nonmagnetic grain boundary material of the initial magnetic layer is Ta2O5, although only slightly better.

[0233] <(F) Study on the effect of adding Fe as the metal component in the initial magnetic layer of the in-plane magnetization film of a CoPt-nonmagnetic oxide multilayer structure (initial magnetic layer: CoPt-ZnO in-plane magnetization film, main magnetic layer: CoPt-B2O3 in-plane magnetization film) on the coercivity Hc and remanence Mrt per unit area (Examples 4, 21)>

[0234] In Example 21, an initial magnetic layer of CoPtFe-ZnO was formed by sputtering to prepare a sample for measuring magnetic properties and obtain experimental data.

[0235] Specifically, using a (Co-25Pt-1Fe)-10 vol% ZnO sputtering target, a 15 nm thick (Co-26.11Pt-0.78Fe)-4.44 vol% ZnO initial magnetic layer is formed by sputtering on a surface-oxidized silicon substrate, that is, on an extremely smooth silicon oxide layer with a surface roughness Ra (arithmetic mean roughness) of 0.1 nm, which serves as the insulating layer and becomes the base layer.

[0236] Then, on the formed initial magnetic layer, a Ru non-magnetic initial intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic initial intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the first magnetic layer, is formed by sputtering. On the formed (Co-26.12Pt)-10 vol% B2O3 in-plane magnetized film of 15 nm, serving as the main body of the first magnetic layer, a Ru non-magnetic intermediate layer with a thickness of 1 nm is formed by sputtering. On the formed Ru non-magnetic intermediate layer with a thickness of 1 nm, an in-plane magnetized film of (Co-26.12Pt)-10 vol% B2O3 with a thickness of 15 nm, serving as the main body of the second magnetic layer, is formed by sputtering, thereby forming a multilayer structure of in-plane magnetized film.

[0237] On the in-plane magnetized film multilayer structure of Example 21 formed as described above, a carbon capping layer is formed by sputtering to prepare a sample for measuring magnetic properties.

[0238] In all the film formation processes described in Example 21, no substrate heating was performed, and film formation was carried out at room temperature.

[0239] The hysteresis loop of the in-plane magnetized film multilayer structure of Example 21 was measured using a vibrating magnetometer. From the measured hysteresis loop, the coercivity Hc (kOe) and remanence Mr (memu / cm²) were read. 3 ) and saturation magnetization Ms (memu / cm) 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 ), making the read saturated magnetization Ms (memu / cm) 3 Multiplying this by the total thickness of the fabricated CoPt in-plane magnetized film, the saturation magnetization Mst (memu / cm) per unit area of ​​the fabricated in-plane magnetized multilayer structure is calculated. 2 ).

[0240] The experimental results of Example 21 are presented together with the experimental results of Examples 4 and 20 in Table 6 below.

[0241] [Table 6]

[0242]

[0243] As shown in Table 6, in Example 21 where the initial magnetic layer of the in-plane magnetization film has the metal composition of Co, Pt, and Fe, the coercivity Hc is 2.98 kOe and 2.00 kOe or higher, and the remanence Mrt per unit area is 3.31 memu / cm. 2 and 2.00 memu / cm 2 The above methods can also yield good magnetic properties.

[0244] Industrial availability

[0245] The in-plane magnetization film and the multilayer structure of the in-plane magnetization film of the present invention can achieve a coercivity Hc of 2.00 kOe or more and a remanence Mrt of 2.00 memu / cm per unit area without heating the film formation process. 2 The above-mentioned magnetic properties are industrially applicable. Furthermore, the hard bias layer of the present invention, having an in-plane magnetization film or a multilayer structure of in-plane magnetization film, exhibits excellent magnetic properties and is industrially applicable. Additionally, the magnetoresistive effect element of the present invention, having a hard bias layer with excellent magnetic properties, is industrially applicable. Furthermore, using the sputtering target of the present invention, an initial magnetic layer of the in-plane magnetization film of the present invention with excellent magnetic properties can be formed by room temperature deposition, making it industrially applicable.

[0246] Symbol Explanation

[0247] 10, 20, 30, 40, 200… magnetoresistive effect elements

[0248] 12, 204… In-plane magnetization film

[0249] 12A, 22A, 32A, 42A… initial magnetic layers

[0250] 12B, 22B... Main body of magnetic layer

[0251] 14, 24, 34, 44, 206… Hard bias layers

[0252] 22, 32, 42… multi-layer structure of in-plane magnetized film

[0253] 22C, 42D… Non-magnetic initial intermediate layer

[0254] 32B, 42B… Main body of the first magnetic layer

[0255] 32C, 42C... Main body of the second magnetic layer

[0256] 32D, 42E... non-magnetic interlayer

[0257] 50…Magnetic shielding layer

[0258] 52…seed layer

[0259] 54…Antiferromagnetic layer

[0260] 56…stapled layer

[0261] 58…Blocking layer

[0262] 60… Free magnetic layer

[0263] 62…cap layer

[0264] 70…Insulation layer

[0265] 202…Ru basal layer

Claims

1. An in-plane magnetizing film, which is used as a hard bias layer for a magnetoresistive effect element, characterized in that, have: An initial magnetic layer containing metallic Co, metallic Pt, and nonmagnetic grain boundary material, with a thickness of 1 nm or more and 32 nm or less, wherein, relative to the total metal composition, it contains metallic Co of 44 atomic% or more and 82 atomic% or less, metallic Pt of 18 atomic% or more and 56 atomic% or less, and the nonmagnetic grain boundary material of 2.0 vol% or more and 31.0 vol% or less, relative to the total volume; and A magnetic layer body formed on the initial magnetic layer and containing metallic Co, metallic Pt, and non-magnetic oxides, wherein, relative to the total metal content, it contains metallic Co of 44 atomic% to 82 atomic% and metallic Pt of 18 atomic% to 56 atomic%; and relative to the total volume, it contains the non-magnetic oxides of 2.0 vol% to 31.0 vol%. The nonmagnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer is formed on a substrate layer with a surface roughness of 0.1 nm or more and 1.5 nm or less. The non-magnetic oxide in the main body of the magnetic layer contains boron oxide.

2. The in-plane magnetization film according to claim 1, characterized in that, The initial magnetic layer also contains Fe metal, and relative to the total metal composition, it contains a total of 44 atomic% or more and 82 atomic% of Co metal and Fe metal, and 18 atomic% or more and 56 atomic% of Pt metal.

3. The in-plane magnetization film according to claim 1, characterized in that, The base layer is an insulating layer.

4. A multilayer structure of in-plane magnetized film, which is used as a hard bias layer for magnetoresistive effect elements, characterized in that, have: An initial magnetic layer containing metallic Co, metallic Pt, and non-magnetic grain boundary material with a thickness of 1 nm or more and 32 nm or less, wherein, relative to the total metal composition, it contains metallic Co of 44 atomic% or more and 82 atomic% or less, metallic Pt of 18 atomic% or more and 56 atomic% or less, and the non-magnetic grain boundary material of 2.0 vol% or more and 31.0 vol% or less, relative to the total volume. A non-magnetic initial intermediate layer formed on the initial magnetic layer; and A magnetic layer body formed on the non-magnetic initial intermediate layer and containing metallic Co, metallic Pt, and non-magnetic oxides, wherein, relative to the total metal composition, it contains metallic Co of 44 atomic% to 82 atomic% and metallic Pt of 18 atomic% to 56 atomic%; and relative to the total volume, it contains the non-magnetic oxides of 2.0 vol% to 31.0 vol%. The nonmagnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer is formed on a substrate layer with a surface roughness of 0.1 nm or more and 1.5 nm or less. The non-magnetic oxide in the main body of the magnetic layer contains boron oxide.

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 an initial magnetic layer, two or more magnetic main bodies, and a non-magnetic intermediate layer. The initial magnetic layer contains metallic Co, metallic Pt, and non-magnetic grain boundary material. Relative to the total metallic content, it contains 44 atomic% to 82 atomic% metallic Co and 18 atomic% to 56 atomic% metallic Pt. Relative to the total volume, it contains 2.0 vol% to 31.0 vol% of the non-magnetic grain boundary material. The thickness of the initial magnetic layer is 1 nm to 32 nm. Each of the two or more magnetic layers contains metallic Co, metallic Pt, and non-magnetic oxides. Relative to the total metal content, it contains 44 atomic% to 82 atomic% metallic Co and 18 atomic% to 56 atomic% metallic Pt. Relative to the total volume, it contains 2.0 vol% to 31.0 vol% of the non-magnetic oxides. The lowest magnetic layer body of the two or more magnetic layer bodies is formed on the initial magnetic layer. The non-magnetic intermediate layers are disposed between the magnetic layer main bodies and are ferromagnetically coupled to each other, sandwiching the non-magnetic intermediate layers. The nonmagnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer is formed on a substrate layer with a surface roughness of 0.1 nm or more and 1.5 nm or less. The non-magnetic oxide in the main body of the magnetic layer contains boron oxide.

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 an initial magnetic layer, a non-magnetic initial intermediate layer formed on the initial magnetic layer, two or more magnetic layer main bodies and non-magnetic intermediate layers. The initial magnetic layer contains metallic Co, metallic Pt, and non-magnetic grain boundary material. Relative to the total metallic content, it contains 44 atomic% to 82 atomic% metallic Co and 18 atomic% to 56 atomic% metallic Pt. Relative to the total volume, it contains 2.0 vol% to 31.0 vol% of the non-magnetic grain boundary material. The thickness of the initial magnetic layer is 1 nm to 32 nm. Each of the two or more magnetic layers contains metallic Co, metallic Pt, and non-magnetic oxides. Relative to the total metal content, it contains 44 atomic% to 82 atomic% metallic Co and 18 atomic% to 56 atomic% metallic Pt. Relative to the total volume, it contains 2.0 vol% to 31.0 vol% of the non-magnetic oxides. The lowest magnetic layer body of the two or more magnetic layers is formed on the non-magnetic initial intermediate layer. The non-magnetic intermediate layers are disposed between the magnetic layer main bodies and are ferromagnetically coupled to each other, sandwiching the non-magnetic intermediate layers. The nonmagnetic grain boundary material of the initial magnetic layer contains at least one of Zn oxide and Ta oxide. The initial magnetic layer is formed on a substrate layer with a surface roughness of 0.1 nm or more and 1.5 nm or less. The non-magnetic oxide in the main body of the magnetic layer contains boron oxide.

7. The in-plane magnetized film multilayer structure according to claim 4 or 6, characterized in that, The non-magnetic initial intermediate layer is composed of Ru or a Ru alloy.

8. The in-plane magnetized film multilayer structure according to claim 4 or 6, characterized in that, The thickness of the non-magnetic initial intermediate layer is greater than 0.3 nm and less than 2 nm.

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

10. The in-plane magnetized film multilayer structure according to claim 5 or 6, characterized in that, The thickness of the non-magnetic intermediate layer is greater than 0.3 nm and less than 2 nm.

11. The multilayer structure of in-plane magnetized film according to any one of claims 4 to 6, characterized in that, The initial magnetic layer also contains Fe metal, and relative to the total metal composition, it contains a total of 44 atomic% or more and 82 atomic% of Co metal and Fe metal, and 18 atomic% or more and 56 atomic% of Pt metal.

12. The multilayer structure of in-plane magnetized film according to any one of claims 4 to 6, characterized in that, The base layer is an insulating layer.

13. A hard bias layer, characterized in that, It has the in-plane magnetization film as described in claim 3.

14. A hard bias layer, characterized in that, It has the in-plane magnetization film multilayer structure as described in claim 12.

15. A magnetoresistive effect element, characterized in that, It has the hard bias layer as described in claim 13.

16. A magnetoresistive effect element, characterized in that, It has the hard bias layer as described in claim 14.

17. A sputtering target used in forming the in-plane magnetized film of claim 1 by room temperature deposition, characterized in that, Contains metallic Co, metallic Pt, and non-magnetic grain boundary materials. Relative to the total metal composition of the sputtering target, it contains 60 atomic% to 82 atomic% of Co and 18 atomic% to 40 atomic% of Pt. The sputtering target contains 6% to 30% by volume of the aforementioned non-magnetic grain boundary material relative to the entire target. The nonmagnetic grain boundary material contains at least one of Zn oxide and Ta oxide.

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