JP2011096333A - Method for manufacturing perpendicular magnetic recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a perpendicular magnetic recording medium allowing higher recording density by enhancing an SNR without deteriorating a recording track width MWW. <P>SOLUTION: The method for manufacturing the perpendicular magnetic recording medium includes a step of forming at least a first magnetic layer 161 containing at least magnetic particles, on a substrate 110, a step of forming a first separation layer 171 consisting essentially of a Ru alloy, on the first magnetic layer, a step of forming a second magnetic layer 162 containing magnetic particles on the first separation layer, a step of forming a second separation layer 172 consisting essentially of a Ru alloy, on the second magnetic layer and a step of forming a third magnetic layer 163 containing at least Co, Cr and Pt, on the second separation layer, wherein the pressure of an atmospheric gas used for film-deposition using a sputtering method is made lower for the second magnetic layer than for the first magnetic layer, and that is made lower for the third magnetic layer than for the second magnetic layer. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a perpendicular magnetic recording medium mounted on a perpendicular magnetic recording type HDD (hard disk drive) or the like.

Various information recording techniques have been developed with the recent increase in information processing capacity. In particular, the surface recording density of HDDs using magnetic recording technology continues to increase at an annual rate of about 100%. Recently, an information recording capacity exceeding 320 GB / platter has been required for a 2.5-inch diameter magnetic recording medium used for HDDs and the like, and in order to meet such a request, 500 GB / inch is required. It is required to realize an information recording density exceeding ² .

  In recent years, a perpendicular magnetic recording system has been proposed in order to achieve a high recording density in a magnetic recording medium used for an HDD or the like. The perpendicular magnetic recording medium used for the perpendicular magnetic recording system is adjusted so that the easy axis of magnetization of the magnetic recording layer is oriented in the direction perpendicular to the substrate surface. Compared with the conventional in-plane magnetic recording system, the perpendicular magnetic recording system can suppress the so-called thermal fluctuation phenomenon in which the thermal stability of the recording signal is lost due to the superparamagnetic phenomenon and the recording signal disappears. It is suitable for increasing the recording density.

  In order to achieve higher recording density in a perpendicular magnetic recording medium, various techniques for improving the characteristics of the medium (electromagnetic conversion characteristics, magnetostatic characteristics, etc.) have been proposed and disclosed. For example, Patent Document 1 discloses a magnetic recording medium in which a magnetic recording layer includes a dividing layer made of Ru, Rh, Ir, or the like. Thereby, it is said that SNR (Signal Noise Ratio) can be improved while maintaining thermal stability.

  On the other hand, in Patent Document 2, a first magnetic recording layer is formed on a substrate with a high atmospheric gas pressure using a sputtering method, and a second magnetic recording layer is formed on the first magnetic recording layer with a low atmospheric gas pressure. A method for manufacturing a magnetic recording medium for forming a magnetic recording layer is disclosed. Thereby, impact resistance can be improved.

JP 2001-056923 A JP 2008-108415 A

However, in order to realize the information recording density exceeding 500 GBit / Inch ² described above in the perpendicular magnetic recording medium, it is necessary to further improve the characteristics of the medium (electromagnetic conversion characteristics, magnetostatic characteristics, etc.). In particular, it is necessary to improve the SNR while maintaining the recording track width MWW.

  The present invention has been made in view of such problems, and manufacturing a perpendicular magnetic recording medium that can realize further higher recording density by improving the SNR without deteriorating the recording track width MWW. It aims to provide a method.

  In order to solve the above-mentioned problems, the present inventors have intensively studied, and when a nonmagnetic dividing layer is interposed in the magnetic recording layer, the magnetic particles are separated too much, which hinders the improvement of SNR. I thought that it might be. As a result of further research, it has been found that such a tendency occurs when two or more layers of dividing faults are interposed, and the present invention has been completed.

  That is, a typical configuration of the method for manufacturing a perpendicular magnetic recording medium according to the present invention includes a step of forming a first magnetic layer containing at least a magnetic particle whose main component is a CoCrPt alloy on a substrate, Forming a first dividing layer mainly composed of an Ru alloy above the magnetic layer, and forming a second magnetic layer containing magnetic particles mainly composed of a CoCrPt alloy above the first dividing layer. A step of forming a second dividing layer comprising a Ru alloy as a main component above the second magnetic layer, and a third magnetic material containing at least Co, Cr, and Pt above the second dividing layer. Forming a layer, each film forming step is performed using a sputtering method, and the pressure of the atmospheric gas when forming the film using the sputtering method is set, and the second magnetic layer is formed by the first magnetic layer. The third magnetic layer is lower than the second magnetic layer. Characterized in that it in.

  By interposing a dividing layer in the magnetic recording layer, the magnetic connection between the upper and lower layers can be adjusted. Thereby, recording / reproducing characteristics such as SNR can be improved while maintaining a magnetostatic value related to thermal fluctuation resistance such as Hc and Hn. In the above configuration, since two dividing lines are interposed in the magnetic recording layer, a high SNR improvement effect can be obtained by the two dividing lines.

  However, it has been found that when two or more dividing layers are interposed, the separation effect of magnetic particles by the dividing layer becomes too strong, which may deteriorate the characteristics. Therefore, in the present invention, the magnetic layer formed immediately above the dividing layer is formed at an atmospheric gas pressure lower than that of the lower magnetic layer. As a result, it is possible to prevent the magnetic particles from being separated excessively, and it is possible to suitably obtain the SNR without deteriorating the recording track width MWW.

  The first magnetic layer and the second magnetic layer may have a granular structure including magnetic particles mainly composed of a CoCrPt alloy and nonmagnetic grain boundary portions mainly composed of an oxide. In the magnetic layer having a granular structure, since the magnetic particles are separated into columns, the magnetic particles are easily separated excessively when a dividing layer is interposed. Therefore, as described above, the SNR can be effectively improved by forming a film immediately above the dividing line with a low gas pressure.

  The third magnetic layer preferably does not contain an oxide. By making the third magnetic layer a magnetically continuous magnetic layer that does not contain an oxide, the reverse magnetic domain nucleation magnetic field Hn and the coercive force Hc are adjusted to improve the heat-resistant fluctuation characteristics and SNR. be able to.

  The third magnetic layer may be CoCrPtB. When the third magnetic layer is made of CoCrPtB, the SNR can be suitably obtained.

  The method further includes a step of forming a base layer containing Ru as a main component on the substrate side from the first magnetic layer by a sputtering method, wherein the pressure of the atmospheric gas when forming the first magnetic layer using the sputtering method is adjusted. The pressure is preferably lower than the pressure for forming the underlayer. Thereby, the crystal orientation of the magnetic recording layer can be improved. When a plurality of underlayers are formed, the atmospheric gas pressure during the formation of the first magnetic layer may be set to be equal to or lower than the pressure of the underlayer close to the first magnetic layer.

  The first magnetic layer may be formed at an atmospheric gas pressure of 3 Pa or higher, and the third magnetic layer may be formed at an atmospheric gas pressure of 1 Pa or lower. Thereby, the degree of separation of magnetic particles can be optimized in the presence of a plurality of dividing lines.

  According to the present invention, it is possible to provide a method of manufacturing a perpendicular magnetic recording medium that can realize further higher recording density by improving the SNR without deteriorating the recording track width MWW.

It is a figure explaining the structure of a perpendicular magnetic recording medium. It is a figure explaining an Example and a comparative example.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding of the invention, and do not limit the present invention unless otherwise specified. In the present specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals, and redundant description is omitted, and elements not directly related to the present invention are not illustrated. To do.

[Method of manufacturing perpendicular magnetic recording medium]
FIG. 1 is a diagram for explaining the configuration of the perpendicular magnetic recording medium 100. A perpendicular magnetic recording medium 100 shown in FIG. 1 includes a substrate 110, an adhesion layer 120, a soft magnetic layer 130, a pre-underlayer 140, an underlayer 150, a magnetic recording layer 160, a dividing layer 170, a protective layer 190, and a lubricating layer 200. Has been.

  Hereinafter, a method for manufacturing the perpendicular magnetic recording medium 100 will be described in detail. The perpendicular magnetic recording medium 100 is manufactured by laminating the above layers on a substrate 110. In particular, the layers from the adhesion layer 120 to the protective layer 190 are sequentially formed by a DC magnetron sputtering method. The protective layer 190 is formed by a CVD method. In general, an in-line type film forming apparatus is used for the lamination because of high productivity. The lubricating layer 200 is formed by a dip coating method.

  As the substrate 110, for example, a glass disk obtained by forming amorphous aluminosilicate glass into a disk shape by direct pressing can be used. The type, size, thickness, etc. of the glass disk are not particularly limited. Examples of the material of the glass disk include aluminosilicate glass, soda lime glass, soda aluminosilicate glass, aluminoborosilicate glass, borosilicate glass, quartz glass, chain silicate glass, or glass ceramic such as crystallized glass. It is done. The glass disk can be ground, polished, and chemically strengthened in order to obtain a smooth nonmagnetic substrate 110 made of the chemically strengthened glass disk.

  An adhesion layer 120 is formed on the substrate 110. The adhesion layer 120 has a function of increasing the adhesion strength between the soft magnetic layer 130 and the substrate 110 laminated immediately above. The adhesion layer 120 is preferably an amorphous (amorphous) alloy film, and the film thickness can be, for example, about 2 to 20 nm.

  The composition of the adhesion layer 120 can be selected from, for example, a CrTi amorphous alloy, a CoW amorphous alloy, a CrW amorphous alloy, a CrTa amorphous alloy, a CrNb amorphous alloy, and the like. . The adhesion layer 120 may be a single layer or may be formed by stacking a plurality of layers.

  A soft magnetic layer 130 is formed on the adhesion layer 120. The soft magnetic layer 130 serves to help the signal writing to the magnetic recording layer and increase the density by converging the write magnetic field from the head when recording a signal in the perpendicular magnetic recording system. As the soft magnetic material, in addition to cobalt-based alloys such as CoTaZr, FeCo-based alloys such as FeCoCrB, FeCoTaZr, and FeCoNiTaZr, and materials exhibiting soft magnetic properties such as NiFe-based alloys can be used. In addition, a spacer layer made of Ru may be interposed approximately in the middle of the soft magnetic layer 130 to provide AFC (Antiferro-magnetic exchange coupling). By doing so, the perpendicular component of magnetization can be extremely reduced, so that noise generated from the soft magnetic layer 130 can be reduced. When the spacer layer is interposed, the thickness of the soft magnetic layer 130 can be about 0.3 to 0.9 nm for the spacer layer and about 10 to 50 nm for the upper and lower layers of the soft magnetic material. .

  A pre-underlayer 140 is formed on the soft magnetic layer 130. The pre-underlayer 140 has a function of promoting the crystal orientation of the hexagonal close-packed structure (hcp structure) included in the underlayer 150 laminated immediately above and a function of controlling a fine structure such as a grain size. The pre-underlayer 140 may have an hcp crystal structure, but preferably has a face-centered cubic structure (fcc crystal structure) oriented so that the (111) plane is parallel to the main surface of the substrate 110. Examples of the material of the pre-underlayer 140 include Ni, Cu, Pt, Pd, Ru, Co, Hf, and one or more of V, Cr, Mo, W, Ta, and the like mainly containing these metals. It can be an added alloy. Specifically, NiV, NiCr, NiTa, NiW, NiVCr, CuW, CuCr and the like can be suitably selected. The film thickness of the pre-underlayer 140 can be about 1 to 20 nm. Further, the pre-underlayer 140 may have a multi-layer structure.

  On the pre-underlayer 140, an underlayer 150 having an hcp structure is formed. The underlayer 150 has a function of accelerating the crystal orientation of the magnetic crystal grains of the hcp structure of the magnetic recording layer 160 and a function of controlling a fine structure such as a grain size. The first magnetic layer 161 and the second magnetic layer 161 are described later. In other words, the magnetic layer 162 is a layer serving as a foundation of the granular structure. Since Ru has the same hcp structure as Co and the lattice spacing of the crystal is close to Co, magnetic grains mainly composed of Co can be well oriented. Therefore, the higher the crystal orientation of the underlayer 150, the more the crystal orientation of the magnetic recording layer 160 can be improved. Refined. Ru is a typical material for the underlayer 150, but metals such as Cr and Co, and oxides can also be added. The film thickness of the underlayer 150 can be, for example, about 5 to 40 nm.

  Note that the base layer 150 may have a two-layer structure by changing the gas pressure during sputtering. Specifically, when forming the upper layer side of the underlayer 150, if the Ar gas pressure is set higher than when forming the lower layer side, the crystal orientation of the upper magnetic recording layer 160 is maintained well, It is possible to reduce the particle size of the magnetic particles.

  In this embodiment, the atmospheric gas pressure when forming the upper base layer 150 is set to be higher than any of the magnetic recording layers 160. As a result, the grain size and separability of the magnetic grains of the magnetic recording layer 160 can be suitably controlled, and a narrow track and a high SNR can be obtained with a sufficient coercive force Hc.

  On the underlayer 150, a magnetic recording layer 160 with a dividing layer 170 interposed is formed. That is, in this embodiment, the first magnetic layer 161, the first dividing layer 171, the second magnetic layer 162, the second dividing layer 172, and the third magnetic layer 163 are formed. Hereinafter, the first magnetic layer 161, the second magnetic layer 162, and the third magnetic layer 163 are collectively referred to as a magnetic recording layer 160. Further, the first dividing fault 171 and the second dividing fault 172 are collectively referred to as a dividing fault 170.

The first magnetic layer 161 has a columnar granular structure in which a grain boundary is formed by segregating a non-magnetic substance mainly composed of an oxide around a ferromagnetic magnetic particle mainly composed of a Co—Pt alloy. Have. For example, SiO ₂ or the CoCrPt-based alloy, by forming a film by using a target obtained by mixing such TiO _2, SiO ₂ and a non-magnetic material around the magnetic particles (grains) composed of a CoCrPt alloy, TiO ₂ Can segregate to form grain boundaries and form a granular structure in which magnetic grains grow in a columnar shape. The atmospheric gas pressure when sputtering the first magnetic layer 161 is preferably set to 3 Pa or higher. As a result, the film structure of the underlayer 150 can be inherited, and the columnar magnetic particles can be epitaxially grown while being suitably separated. Therefore, the coercive force Hc can be secured and the track can be narrowed, and a high SNR can be realized.

  The first magnetic layer 161 can be composed of a plurality of layers. In that case, it is more preferable that the upper layer is formed under a lower atmospheric gas pressure. Similarly, the second magnetic layer 162 and the third magnetic layer 163 may be composed of a plurality of layers, and the upper layer may be formed under a lower atmospheric gas pressure.

The material used for the first magnetic layer 161 described above is an example, and the present invention is not limited to this. As the CoCrPt-based alloy, one or more kinds of B, Ta, Cu, etc. may be added to CoCrPt. Examples of nonmagnetic substances for forming grain boundaries include silicon oxide (SiO ₂ ), titanium oxide (TiO ₂ ), chromium oxide (Cr ₂ O ₃ ), zircon oxide (ZrO ₂ ), and tantalum oxide (for example). Examples thereof include oxides such as Ta ₂ O ₅ ) and cobalt oxide (CoO or Co ₃ O ₄ ). Further, not only one kind of oxide but also two or more kinds of oxides can be used in combination.

  The first dividing layer 171 is provided above the first magnetic layer 161 and below the second magnetic layer 162, and has an action of adjusting the magnetic connection between the upper and lower layers, that is, the strength of exchange coupling. As a result, it is possible to improve recording characteristics such as overwrite characteristics and SNR while maintaining magnetostatic values relating to thermal fluctuation resistance such as Hc and Hn. In order to obtain good exchange coupling strength, the film thickness of the first dividing layer 171 is preferably in the range of 0.2 to 1.0 nm.

  As an effect on the structure of the first dividing fault 171, there is an effect of promoting the separation of the upper crystal grains. However, when this action works excessively, the magnetic particles are non-uniformly separated and the magnetic properties such as coercive force Hc and SNR are rather deteriorated. In general, when a plurality of dividing layers 170 are included in the magnetic recording layer, the separation tends to be excessive as a whole. Therefore, in the present embodiment, it is possible to adjust the degree of separation of the magnetic particles by changing the atmospheric gas pressure at the time of forming the magnetic recording layer 160. The effect obtained by this is particularly remarkable for a granular structure in which magnetic particles are separated in a columnar shape, and can effectively improve the SNR.

The first dividing line 171 is preferably a layer mainly composed of a Ru alloy having an hcp crystal structure so as not to lower the inheritance of crystal orientation. That is, in addition to Ru, Ru added with other metal elements, oxygen, or oxide can be used. It is also possible to substitute a Co alloy as the main component. As the Co-based material, a CoCr alloy or the like can be used. Specific examples include Ru, RuCr, RuCo, Ru—SiO 2, Ru—WO ₃ , Ru—TiO ₂ , CoCr, CoCr—SiO ₂ , and CoCr—TiO ₂ . The first dividing line 171 is preferably non-magnetic, but may have weak magnetism.

  Similar to the first magnetic layer 161, the second magnetic layer 162 has a granular structure (the description is omitted because it is described above), and is formed immediately above the first dividing layer 171. The composition, film thickness, and the like of the second magnetic layer 162 are not necessarily the same as those of the first magnetic layer 161, and may be selected as appropriate. The second magnetic layer 162 is formed at a lower atmospheric gas pressure than the first magnetic layer 161. As a result, it is possible to prevent the magnetic particles from being excessively separated and to improve the SNR without deteriorating the recording track width MWW.

  The second dividing line 172 is provided above the second magnetic layer 162 and below the third magnetic layer 163, and adjusts the magnetic connection between the upper and lower layers in the same manner as the first dividing line 171. Since the description of the first split fault 171 described above can be applied to the second split fault 172, the description thereof is omitted. However, the composition, film thickness, and the like of the second dividing fault 172 need not be the same as those of the first dividing fault 171 and may be selected as appropriate.

  The third magnetic layer 163 is a magnetic layer that is substantially magnetically continuous in the in-plane direction of the main surface of the substrate, and is formed immediately above the second dividing layer 172. The third magnetic layer 163 may have a magnetic interaction (exchange coupling) with the first magnetic layer 161 and the second magnetic layer 162. By doing so, the magnetic grains separated by the nonmagnetic grain boundary portions in the first and second magnetic layers can be magnetically coupled through the upper third magnetic layer. That is, by adjusting the magnetostatic characteristics such as the coercive force Hc and the reverse domain nucleation magnetic field Hn by the magnetic coupling in the vertical direction and the horizontal direction, the thermal fluctuation resistance, the OW characteristics, and the SNR are improved. Can do.

  In the present embodiment, the third magnetic layer 163 is formed with an atmospheric gas pressure lower than that of the second magnetic layer 162. In particular, it is preferable to form a film at an atmospheric gas pressure of 1 Pa or less. Accordingly, it is possible to prevent the magnetic particles from being excessively separated by the two dividing lines, and to improve the SNR without deteriorating the recording track width MWW.

  As a material of the third magnetic layer 163, at least Co, Cr, and Pt are contained. For example, a CoCrPt-based alloy can be used, and further additives such as B, Ta, and Cu may be added. Specifically, CoCrPt, CoCrPtB, CoCrPtTa, CoCrPtCu, CoCrPtCuB, or the like can be used. The film thickness of the third magnetic layer 163 can be set to 3 to 10 nm, for example.

  Note that “magnetically continuous” means that magnetism is connected without interruption. “Substantially continuous” means that the third magnetic layer 163 as a whole is not necessarily a single magnet but may be partially discontinuous in magnetism. That is, the third magnetic layer 163 only needs to be continuous in magnetism so as to straddle (cover) an aggregate of a plurality of magnetic particles. As long as this condition is satisfied, the third magnetic layer 163 may have a structure in which, for example, Cr is segregated.

  A protective layer 190 for protecting the perpendicular magnetic recording medium 100 from impact and corrosion of the magnetic head is formed on the magnetic recording layer 160 (third magnetic layer 163) with the dividing layer 170 interposed. The protective layer 190 can be formed by forming a film containing carbon by a CVD method. In general, the carbon-based protective film formed by the CVD method is denser and the film hardness is improved as compared with the film formed by the sputtering method, so that the perpendicular magnetic recording medium 100 is more effectively applied to the impact from the magnetic head. It is preferable because it can be protected. The film thickness of the protective layer 190 can be 2-6 nm, for example.

  On the protective layer 190, the lubricating layer 200 is formed. The lubricating layer 200 is formed to prevent the protective layer 190 from being damaged when the magnetic head comes into contact with the surface of the perpendicular magnetic recording medium 100. For example, PFPE (perfluoropolyether) can be applied by dip coating to form a film. The film thickness of the lubricating layer 200 can be set to 0.5 to 2.0 nm, for example.

  The method for manufacturing the perpendicular magnetic recording medium 100 according to the present embodiment has been described above. According to the configuration described above, since the magnetic layer formed immediately above the dividing layer 170 is formed at a lower atmospheric gas pressure than the lower magnetic layer, the magnetic particles can be obtained while obtaining the effect of the dividing layer 170. An excessive separation can be prevented, and an SNR can be suitably obtained without deteriorating the recording track width MWW. In particular, in this embodiment, the underlayer 150 is formed at the highest atmospheric gas pressure, the first magnetic layer 161 is formed at an atmospheric gas pressure lower than the underlayer 150 and 3 Pa or higher, and the second magnetic layer 162 may be formed at an atmospheric gas pressure lower than that of the first magnetic layer 161, and the third magnetic layer 163 may be formed at an atmospheric gas pressure lower than that of the second magnetic layer 162 and 1 Pa or less. As a result, it is possible to optimize the degree of separation of magnetic particles while optimizing the magnetic coupling between the magnetic layers by a plurality of dividing layers, and to achieve an SNR that can realize further higher recording density. .

[Example]
FIG. 2 is a diagram illustrating an example and a comparative example. Hereinafter, the effectiveness of the method for manufacturing the perpendicular magnetic recording medium 100 according to the present embodiment will be verified using Examples 1 to 3 and Comparative Examples 1 to 5 shown in FIG.

As an example and a comparative example, on the substrate 110, a film was formed from the adhesion layer 120 to the third magnetic layer 163 in an Ar atmosphere by a DC magnetron sputtering method using a vacuum-deposited film forming apparatus. It was. Unless otherwise noted, the Ar gas pressure during film formation is 0.6 Pa. The adhesion layer 120 was formed by depositing Cr-50Ti with a thickness of 10 nm. As the soft magnetic layer 130, 92 (40Fe-60Co) -3Ta-5Zr was formed to a thickness of 20 nm with a 0.7 nm Ru layer interposed therebetween. The pre-underlayer 140 was formed with 8 nm of Ni-5W. The underlayer 150 was formed by depositing 10 nm of Ru at 0.6 Pa and then depositing 10 nm of Ru at 5 Pa. The magnetic recording layer 160 with the dividing layer 170 interposed was prepared and compared as described in the following examples and comparative examples. The protective layer 190 was formed to a thickness of 4 nm using C ₂ H ₄ by a CVD method, and the surface layer was nitrided. The lubricating layer 200 was formed to 1 nm using PFPE by a dip coating method.

In Examples 1 to 3 and Comparative Examples 1 to 5 shown in FIG. 2, the composition of the first magnetic layer 161 and the second magnetic layer 162 is 90 (71Co13Cr16Pt) -5SiO ₂ -5TiO _2, and the composition of the third magnetic layer 163 is Was 62Co-18Cr-15Pt-5B. The composition of the first dividing fault 171 and the second dividing fault 172 was Ru. In Examples 2 and 3, the first magnetic layer 161 was further divided into a plurality of layers to form a lower recording layer, a main recording layer, or an upper recording layer. In this case, the composition of the lower recording layer is _{90 (71Co11Cr18Pt) -5SiO 2 -5TiO 2} , the composition of the main recording layer and _{90 (72Co12Cr16Pt) -5SiO 2 -5TiO 2} , the composition of the upper recording layer 90 (71Co13Cr16Pt) It was -5SiO ₂ -5TiO _2.

  In Example 1, the first magnetic layer 161 was formed to a thickness of 11.8 nm under an atmospheric gas pressure of 4.0 Pa. A first split layer 171 was formed to a thickness of 0.5 nm under an atmospheric gas pressure of 0.6 Pa. The second magnetic layer 162 was formed to a thickness of 2.7 nm under an atmospheric gas pressure of 3.0 Pa. A second split layer 172 was formed to a thickness of 0.4 nm under an atmospheric gas pressure of 0.6 Pa. The third magnetic layer 163 was formed to a thickness of 5.4 nm under an atmospheric gas pressure of 1.0 Pa. In Examples 2 and 3 and Comparative Examples 1 to 5, the gas pressure and film thickness shown in FIG.

  Examples 1 to 3 and Comparative Examples 1 to 5 will be described in detail with reference to FIG. First, when Example 1 in which the magnetic layer on the upper side of the dividing layer 170 was formed at a lower gas pressure than Comparative Example 1 was compared with Comparative Example 1 in which all the magnetic recording layers 160 were formed at the same gas pressure, Example 1 was compared. Then, it can be seen that the SNR is improved while maintaining the same or better characteristics at the recording track width MWW, the coercive force Hc, and the reverse domain nucleation magnetic field Hn. In the case of Comparative Example 2 in which only the third magnetic layer 163 is formed at a lower gas pressure than the other magnetic layers, the SNR is slightly improved as compared with Comparative Example 1. From the above, it was confirmed that the degree of separation of the magnetic particles can be adjusted and the SNR can be improved by forming the magnetic layer immediately above the dividing layer 170 at a lower gas pressure than the magnetic layer immediately below. The

  In Comparative Example 3 in which the first magnetic layer 161 is formed at a lower gas pressure than the second magnetic layer 162, the characteristics deteriorate not only in the SNR but also in the recording track width MWW, the coercive force Hc, and the reverse domain nucleation magnetic field Hn. Is seen. This is probably because when the first magnetic layer 161 is formed at a low gas pressure, the magnetic particles are enlarged and the Ru microstructure of the underlayer 150 cannot be inherited.

  Further, in Comparative Example 4 and Comparative Example 5 in which the first dividing fault 171 and the second dividing fault 172 are not interposed, the SNR as good as that in Example 1 cannot be obtained. This is because the exchange coupling adjustment ability exhibited by the dividing fault 170 cannot be obtained when the dividing fault 170 is not interposed.

  On the other hand, the first magnetic layer 161 is divided into a lower recording layer and a main recording layer, and the main recording layer is formed at a lower gas pressure than the lower recording layer (the second magnetic layer 162 has a lower gas pressure than the main recording layer). In Example 2, a better SNR was obtained than in the first example. Further, the first magnetic layer 161 is divided into a lower recording layer, a main recording layer, and an upper recording layer, and the upper magnetic layer 161 is formed at a lower gas pressure (the second magnetic layer 162 has a lower gas pressure than the upper recording layer) upward. 3, an even better SNR was obtained than in the second embodiment. From this, it was confirmed that the magnetic recording layer 160 may be further divided into a plurality of parts, and a favorable SNR can be obtained by forming a film at a lower gas pressure toward the upper side.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this embodiment. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

  For example, in the present embodiment, the third magnetic layer 163 has been described as a magnetic layer that does not include an oxide that is substantially magnetically continuous in the in-plane direction of the main surface of the substrate. However, like the first magnetic layer 161 and the second magnetic layer 162, the third magnetic layer 163 may include an oxide to form a granular structure, and such a configuration is naturally within the scope of the present invention.

  The present invention can be used as a method for manufacturing a perpendicular magnetic recording medium mounted on a perpendicular magnetic recording type HDD (hard disk drive) or the like.

DESCRIPTION OF SYMBOLS 100 ... Perpendicular magnetic recording medium, 110 ... Substrate, 120 ... Adhesion layer, 130 ... Soft magnetic layer, 140 ... Pre-underlayer, 150 ... Underlayer, 160 ... Magnetic recording layer, 161 ... First magnetic layer, 162 ... Second Magnetic layer, 163... Third magnetic layer, 170... Split layer, 171... First split layer, 172.

Claims (6)

At least on the substrate,
Forming a first magnetic layer containing magnetic particles containing a CoCrPt alloy as a main component;
Depositing a first split layer comprising a Ru alloy as a main component above the first magnetic layer;
Forming a second magnetic layer containing magnetic particles containing a CoCrPt alloy as a main component above the first dividing layer;
Forming a second split layer comprising a Ru alloy as a main component above the second magnetic layer;
Forming a third magnetic layer containing at least Co, Cr, and Pt above the second dividing layer;
Including
Any film forming process is performed using a sputtering method,
The pressure of the atmospheric gas when forming the film using the sputtering method is set so that the second magnetic layer has a lower pressure than the first magnetic layer, and the third magnetic layer has a lower pressure than the second magnetic layer. A method of manufacturing a perpendicular magnetic recording medium.   2. The first magnetic layer and the second magnetic layer have a granular structure composed of magnetic particles whose main component is a CoCrPt alloy and nonmagnetic grain boundary portions whose main component is an oxide. 2. A method for producing a perpendicular magnetic recording medium according to 1.   The method of manufacturing a perpendicular magnetic recording medium according to claim 2, wherein the third magnetic layer does not contain an oxide.   The method of manufacturing a perpendicular magnetic recording medium according to claim 3, wherein the third magnetic layer is CoCrPtB. And further including a step of forming a base layer containing Ru as a main component on the substrate side of the first magnetic layer by the sputtering method,
2. The perpendicular magnetic recording according to claim 1, wherein the pressure of the atmospheric gas when forming the first magnetic layer using the sputtering method is set to be equal to or lower than the pressure when forming the underlayer. A method for manufacturing a medium. The first magnetic layer is formed at an atmospheric gas pressure of 3 Pa or more,
The method of manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the third magnetic layer is formed at an atmospheric gas pressure of 1 Pa or less.

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