JP5771427B2 - Magnetic recording medium manufacturing method and magnetic recording / reproducing apparatus - Google Patents

Description

  The present invention relates to a method for manufacturing a magnetic recording medium and a magnetic recording / reproducing apparatus, and more particularly, to a method for manufacturing a magnetic recording medium having a perpendicular magnetic layer in which an easy axis in a magnetic film is oriented perpendicular to a nonmagnetic substrate The present invention relates to a magnetic recording / reproducing apparatus including a magnetic recording medium manufactured by a manufacturing method.

  A hard disk drive (HDD), which is a kind of magnetic recording / reproducing apparatus, has an increasing recording density of 50% or more per year and is said to continue to increase in the future. With the increase in the recording density of hard disk devices, development of magnetic heads and magnetic recording media suitable for increasing the recording density is in progress.

  Some commercially available magnetic recording / reproducing apparatuses are equipped with a so-called perpendicular magnetic recording medium in which an easy axis of magnetization in a magnetic film is vertically oriented. Even when the recording density of the perpendicular magnetic recording medium is increased, the influence of the demagnetizing field in the boundary region between the recording bits is small and a clear bit boundary is formed, so that an increase in noise can be suppressed. In addition, the perpendicular magnetic recording medium is excellent in thermal fluctuation characteristics because it requires only a small decrease in recording bit volume as the recording density increases.

  Further, in order to meet the demand for higher recording density of magnetic recording media, it has been studied to use a single magnetic pole head having excellent writing ability for the perpendicular magnetic layer as a magnetic head. Specifically, by providing a layer made of a soft magnetic material called a backing layer between a perpendicular magnetic layer that is a recording layer and a nonmagnetic substrate, a magnetic flux between a single-pole head and a magnetic recording medium is provided. There has been proposed a magnetic recording medium with improved efficiency of entering and exiting.

  In addition, in order to improve the recording / reproducing characteristics and thermal fluctuation characteristics of the perpendicular magnetic recording medium, an orientation control layer is used to form a multi-layered magnetic layer, and the crystal grains of each magnetic layer are formed into continuous columnar crystals. It has been proposed to improve the vertical alignment of the magnetic layer (see, for example, Patent Document 1).

Also, Ru is used as the orientation control layer (underlayer) of the magnetic recording medium, the orientation control layer has a two-layer structure, the initial layer portion is formed at a low gas pressure, and the surface portion has a higher gas pressure than the initial layer portion. Has been proposed (see, for example, Patent Document 2).
In addition, since Ru has a dome-shaped convex portion formed at the top of the columnar crystal, crystal grains such as a magnetic layer are grown on the convex portion, and the separation structure of the grown crystal particles is promoted. It is known to have an effect of isolating crystal grains and growing magnetic grains in a columnar shape (see, for example, Patent Document 3).

  Further, it has been reported that in the orientation control layer using two layers of Ru, voids (voids) are generated at the grain boundaries of the Ru columnar crystals. For example, Patent Document 4 describes an underlayer composed of crystal grains made of Ru or Ru alloy crystals and voids that separate the crystal grains from each other.

JP 2004-310910 A JP 2004-22138 A JP 2007-272990 A JP 2008-204539 A

  An alignment control layer using two layers of Ru and forming a dome-shaped convex portion at the top of a Ru columnar crystal to enhance the separation of crystal grains is excellent in vertical alignment. However, in such an orientation control layer, as described above, voids are easily formed at the grain boundaries of the columnar crystals. Since the void formed in the orientation control layer is covered with a magnetic layer or the like formed on the orientation control layer, no hole (pit) is generated on the surface of the magnetic recording medium. However, as a result of studies by the inventors of the present application, it has been clarified that when voids are generated in the orientation control layer, the density of the orientation control layer is lowered and the impact resistance of the surface of the magnetic recording medium is lowered.

  Generally, a magnetic recording medium built in a hard disk device is rotated at a high speed when information is recorded / reproduced. By this high speed rotation, a thin air flow is generated on the surface of the magnetic recording medium, and the magnetic head floats on the surface of the magnetic recording medium by the air flow. For this reason, when the magnetic recording medium rotates at high speed, the magnetic recording medium and the magnetic head are not in contact with each other, and there is basically no possibility that the magnetic recording medium is damaged due to contact between the two. Therefore, it is considered that there is little need to obtain impact resistance on the surface of the magnetic recording medium.

  However, depending on the usage environment of the hard disk device, an external impact may be applied during operation, and the magnetic recording medium that rotates at high speed and the magnetic head may accidentally contact each other and the surface of the magnetic recording medium may be damaged. . In order to protect the magnetic recording medium from such accidental contact, a protective layer made of a hard carbon film is usually provided on the surface of the magnetic recording medium. However, in order to increase the recording density of the magnetic recording medium, it is required to reduce the thickness of the protective layer. For this reason, there is a limit to securing the protective ability of the magnetic recording medium by the protective layer, and even if the protective layer is provided, sufficient protective ability may not be obtained.

The present invention has been proposed in view of the above circumstances, and can form an orientation control layer having a two-layer structure with few voids and excellent vertical orientation, and has excellent impact resistance and high recording performance. An object of the present invention is to provide a method of manufacturing a magnetic recording medium that can obtain a magnetic recording medium suitable for the density.
It is another object of the present invention to provide a highly reliable magnetic recording / reproducing apparatus including a magnetic recording medium manufactured by the above magnetic recording medium manufacturing method.

In order to solve the above-mentioned problems, the present inventor has intensively studied the material of the orientation control layer and the film forming method as described below.
That is, the present inventor uses a two-layer orientation control layer in order to form an orientation control layer having excellent vertical orientation, and uses a target containing a CoCr alloy for the nonmagnetic substrate side of the two layers. Then, it was found that by forming by a reactive sputtering method using a sputtering gas containing nitrogen, a columnar layer having a dome-shaped convex portion at the top can be formed as in the case of forming a Ru layer or a Ru alloy layer. It was.

Furthermore, the present inventor has conducted extensive studies and found that voids are unlikely to occur in the layer on the nonmagnetic substrate side of the two layers obtained by the above method, although the reason is not clear. Further, a Ru layer or Ru alloy layer including a columnar crystal having a dome-shaped convex portion at the top is formed as another orientation control layer on the non-magnetic substrate side layer by sputtering. In this case, it was found that voids were not easily generated in the Ru layer or the Ru alloy layer.
Thus, the present inventor has found that the above-described method can form an orientation control layer having a two-layer structure including a columnar crystal having a small number of voids and having a dome-shaped convex portion on the top, and has excellent impact resistance and verticality. The production method of the present invention has been completed which can produce a magnetic recording medium having orientation and suitable for high recording density.

The present invention provides the following means.
(1) On a nonmagnetic substrate, at least a soft magnetic underlayer, an orientation control layer for controlling the orientation of the layer immediately above, and a perpendicular magnetic layer having an easy axis oriented perpendicular to the nonmagnetic substrate And a manufacturing method of a magnetic recording medium formed in this order,
A first film forming step of forming a first orientation control layer by a reactive sputtering method using a sputtering gas containing nitrogen using a target containing a CoCr alloy;
Forming the orientation control layer on the first orientation control layer by performing a second film-forming step of forming a second orientation control layer made of Ru or a Ru alloy using a sputtering method; A method of manufacturing a magnetic recording medium.

(2) In the first film forming step, as the sputtering gas, a gas containing an inert gas and nitrogen in a range of 0.1 volume% to 20 volume% of the inert gas is used. The method for manufacturing a magnetic recording medium according to (1).
(3) The method for manufacturing a magnetic recording medium according to (1) or (2), wherein, in the first film formation step, the pressure of the sputtering gas is in a range of 0.1 Pa to 10 Pa.
(4) In any one of (1) to (3), in the second film formation step, the pressure of the sputtering gas is equal to or higher than the first film formation step and in a range of 5 Pa to 18 Pa. A method for producing the magnetic recording medium according to 1.

(5) In the first film forming step, the first orientation control layer including a first columnar crystal having a dome-shaped convex portion formed on the top is formed by growing a crystal serving as a nucleus,
In the second film forming step, the second orientation control layer including a second columnar crystal that is continuous in a thickness direction with a crystal serving as a nucleus of the first columnar crystal and has a dome-shaped convex portion at the top is formed. (1) The method for manufacturing a magnetic recording medium according to any one of (1) to (4).

(6) The CoCr alloy contains Co in a range of 55 at% to 95 at% and contains Cr in a range of 45 at% to 5 at%, and any one of (1) to (5) A method for producing the magnetic recording medium according to 1.
(7) The CoCr alloy contains one or more elements selected from Pt, B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in a range of 1 at% to 10 at%. The method for producing a magnetic recording medium according to any one of (1) to (6), wherein

(8) A magnetic recording medium manufactured using the method according to any one of (1) to (7), and a magnetic head that records and reproduces information on the magnetic recording medium. Magnetic recording / reproducing apparatus.

  In the method for producing a magnetic recording medium of the present invention, a first orientation control layer is formed by a reactive sputtering method using a sputtering gas containing nitrogen, using a target containing a CoCr alloy, and on the first orientation control layer, Since the orientation control layer is formed by forming a second orientation control layer made of Ru or a Ru alloy using a sputtering method, it has excellent vertical orientation including a columnar crystal having a dome-like convex portion at the top. An orientation control layer can be formed, and on the orientation control layer, a perpendicular magnetic layer containing columnar crystals continuous in the thickness direction with the columnar crystals contained in the orientation control layer can be formed, and a magnetic recording medium suitable for high recording density is obtained. It is done.

In addition, according to the method for manufacturing a magnetic recording medium of the present invention, the first orientation control layer with few voids is formed, so the second orientation control layer with few voids is formed on the first orientation control layer, and as a whole An orientation control layer having a very small void content is formed. As a result, according to the method for manufacturing a magnetic recording medium of the present invention, a magnetic recording medium having excellent impact resistance can be obtained.
In addition, the magnetic recording / reproducing apparatus of the present invention includes a magnetic recording medium manufactured by using the magnetic recording medium manufacturing method of the present invention, and therefore has high reliability.

FIG. 1 is a schematic cross-sectional view showing an example of a magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium of the present invention. FIG. 2 is an enlarged schematic view for explaining the laminated structure of the orientation control layer and the perpendicular magnetic layer in the magnetic recording medium shown in FIG. 1, and shows a state in which columnar crystals of each layer grow perpendicular to the substrate surface. FIG. FIG. 3 is a perspective view showing an example of the magnetic recording / reproducing apparatus of the present invention.

  Hereinafter, a method for manufacturing a magnetic recording medium and a magnetic recording / reproducing apparatus according to the present invention will be described in detail with reference to the drawings. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, the portions that become the features may be shown in an enlarged manner for convenience, and the dimensional ratios of the respective components are the same as the actual ones Not necessarily.

(Method of manufacturing magnetic recording medium)
In the method for producing a magnetic recording medium of the present invention, at least a soft magnetic underlayer, an orientation control layer for controlling the orientation of the layer immediately above, and an easy axis of magnetization on the nonmagnetic substrate. And perpendicularly oriented perpendicular magnetic layers are formed in this order. In the method for manufacturing a magnetic recording medium of the present invention, the first film formation step for forming the first alignment control layer and the second film formation step for forming the second alignment control layer are performed, thereby performing the alignment. A control layer is formed.

Hereinafter, as an example of the method of manufacturing the magnetic recording medium of the present invention, the method of manufacturing the magnetic recording medium shown in FIGS. 1 and 2 will be described in detail.
FIG. 1 is a schematic cross-sectional view showing an example of a magnetic recording medium manufactured using the method for manufacturing a magnetic recording medium of the present invention. FIG. 2 is an enlarged schematic view for explaining the laminated structure of the orientation control layer and the perpendicular magnetic layer in the magnetic recording medium shown in FIG. 1, in which the columnar crystals of each layer are grown perpendicular to the substrate surface. It is sectional drawing which showed. 2, illustration of members other than the first orientation control layer 3a, the second orientation control layer 3b, and the perpendicular magnetic layer 4 constituting the orientation control layer 3 is omitted. In FIG. 1, a nonmagnetic underlayer 8 is provided between the second orientation control layer 3b and the perpendicular magnetic layer 4. This nonmagnetic underlayer 8 is also composed of columnar crystals grown perpendicular to the substrate surface. The columnar crystals are formed continuously with the columnar crystals of the second orientation control layer 3b and the perpendicular magnetic layer 4.

  The magnetic recording medium shown in FIG. 1 includes a soft magnetic underlayer 2, an orientation control layer 3, a nonmagnetic underlayer 8, a perpendicular magnetic layer 4, a nonmagnetic layer 7, and a protection on a nonmagnetic substrate 1. The layer 5 and the lubricating layer 6 are laminated.

"Non-magnetic substrate"
As the nonmagnetic substrate 1, a metal substrate made of a metal material such as aluminum or an aluminum alloy may be used, or a nonmetal substrate made of a nonmetal material such as glass, ceramic, silicon, silicon carbide, or carbon is used. Also good. Further, as the nonmagnetic substrate 1, a substrate in which a NiP layer or a NiP alloy layer is formed on the surface of the metal substrate or the nonmetal substrate by using, for example, a plating method or a sputtering method may be used.

As the glass substrate, for example, amorphous glass or crystallized glass can be used. As the amorphous glass, for example, general-purpose soda lime glass or aluminosilicate glass can be used. In addition, as the crystallized glass, for example, lithium-based crystallized glass can be used.
As the ceramic substrate, for example, general-purpose aluminum oxide, a sintered body mainly composed of aluminum nitride, silicon nitride, or the like, or a fiber reinforced material thereof can be used.

The non-magnetic substrate 1 has an average surface roughness (Ra) of 2 nm (20 mm) or less, preferably 1 nm or less, so that the dome shape of the surface of the orientation control layer 3 is uniform and the height distribution of the top portion is uniform. This is preferable because it is suitable for high recording density recording with a reduced magnetic head and low flying height.
The nonmagnetic substrate 1 has a surface waviness (Wa) of 0.3 nm or less (more preferably 0.25 nm or less), which reduces the height distribution of the dome-shaped top portion of the surface of the orientation control layer 3. However, it is preferable because it is suitable for high recording density recording with a magnetic head flying low. In addition, microwaviness (Wa) can be measured as surface average roughness in a measuring range of 80 μm, for example, using a surface roughness measuring device P-12 (manufactured by KLM-Tencor).
Further, as the nonmagnetic substrate 1, a substrate having an average surface roughness (Ra) of 10 nm or less (more preferably 9.5 nm or less) of at least one of the chamfered portion and the side surface portion of the chamfer portion at the end face is used. This is preferable for the flight stability of the magnetic head.

  Further, when the nonmagnetic substrate 1 is in contact with the soft magnetic underlayer 2 mainly composed of Co or Fe, there is a possibility that the corrosion progresses due to the adsorption gas on the surface, the influence of moisture, the diffusion of the substrate components, and the like. is there. For this reason, it is preferable to provide an adhesion layer between the nonmagnetic substrate 1 and the soft magnetic underlayer 2. By providing the adhesion layer, corrosion can be suppressed. As a material for the adhesion layer, for example, Cr, Cr alloy, Ti, Ti alloy and the like can be selected as appropriate. The thickness of the adhesion layer is preferably 2 nm (30 mm) or more.

"Soft magnetic underlayer"
In order to manufacture the magnetic recording medium shown in FIG. 1, a soft magnetic underlayer 2 is formed on the nonmagnetic substrate 1 described above. The method for forming the soft magnetic underlayer 2 is not particularly limited, and for example, a sputtering method can be used. When an adhesion layer is provided between the nonmagnetic substrate 1 and the soft magnetic underlayer 2, the adhesion layer is formed using, for example, a sputtering method before the soft magnetic underlayer 2 is formed.

  The soft magnetic underlayer 2 is provided in order to increase the perpendicular component of the magnetic flux generated from the magnetic head with respect to the substrate surface and to firmly fix the magnetization direction of the perpendicular magnetic layer 4 in the direction perpendicular to the nonmagnetic substrate 1. It has been. This effect becomes more conspicuous particularly when a single pole head for perpendicular recording is used as a magnetic head for recording and reproduction.

  As the soft magnetic underlayer 2, for example, a soft magnetic material containing Fe, Ni, Co, or the like can be used. Specific examples of soft magnetic materials include CoFe alloys (CoFeTaZr, CoFeZrNb, etc.), FeCo alloys (FeCo, FeCoV, etc.), FeNi alloys (FeNi, FeNiMo, FeNiCr, FeNiSi, etc.), FeAl alloys (FeAl, etc.). FeAlSi, FeAlSiCr, FeAlSiTiRu, FeAlO, etc.), FeCr alloys (FeCr, FeCrTi, FeCrCu, etc.), FeTa alloys (FeTa, FeTaC, FeTaN, etc.), FeMg alloys (FeMgO, etc.), FeZr alloys (FeZrN, etc.) , FeC alloys, FeN alloys, FeSi alloys, FeP alloys, FeNb alloys, FeHf alloys, FeB alloys and the like.

The soft magnetic underlayer 2 has a microcrystalline structure such as FeAlO, FeMgO, FeTaN, FeZrN or the like containing Fe of 60 at% (atomic%) or more, or a granular structure in which fine crystal particles are dispersed in a matrix. Materials can be used.
In addition, as the soft magnetic underlayer 2, a Co alloy containing 80 at% or more of Co, containing at least one of Zr, Nb, Ta, Cr, Mo and the like and having an amorphous structure can be used. . Specific examples of the specific material include CoZr, CoZrNb, CoZrTa, CoZrCr, and CoZrMo-based alloys.

The coercive force Hc of the soft magnetic underlayer 2 is preferably 100 (Oe) or less (preferably 20 (Oe) or less). 1 Oe is 79 A / m. If the coercive force Hc of the soft magnetic underlayer 2 exceeds the above range, the soft magnetic characteristics are insufficient, and the reproduced waveform becomes a waveform having distortion from a so-called rectangular wave, which is not preferable.
The saturation magnetic flux density Bs of the soft magnetic underlayer 2 is preferably 0.6 T or more (preferably 1 T or more). If the Bs of the soft magnetic underlayer 2 is less than the above range, it is not preferable because the reproduced waveform changes from a so-called rectangular wave to a distorted waveform.
The product Bs · t (T · nm) of the saturation magnetic flux density Bs (T) of the soft magnetic underlayer 2 and the layer thickness t (nm) of the soft magnetic underlayer 2 is 15 (T · nm) or more (preferably Is preferably 25 (T · nm) or more. If the Bs · t of the soft magnetic underlayer 2 is less than the above range, the reproduced waveform will be distorted and the OW (OverWrite) characteristic (recording characteristic) will be deteriorated.

  The soft magnetic underlayer 2 is preferably composed of two soft magnetic films, and a Ru film is preferably provided between the two soft magnetic films. By adjusting the film thickness of the Ru film in the range of 0.4 to 1.0 nm or 1.6 to 2.6 nm, the two-layer soft magnetic film can have an AFC (antiferromagnetic exchange coupling) structure. it can. When the soft magnetic underlayer 2 adopts such an AFC structure, so-called spike noise can be suppressed.

  The material constituting the magnetic underlayer 2 is preferably partially or completely oxidized on the outermost surface (surface on the orientation control layer 3 side) of the soft magnetic underlayer 2. For example, it is preferable that the material constituting the soft magnetic underlayer 2 is partially oxidized on the surface of the soft magnetic underlayer 2 or in the vicinity thereof, or an oxide of the above material is formed. Thereby, the magnetic fluctuation of the surface of the soft magnetic underlayer 2 can be suppressed, noise caused by the magnetic fluctuation can be reduced, and the recording / reproducing characteristics of the magnetic recording medium can be improved.

`` Orientation control layer ''
Next, as shown in FIG. 2, the orientation control layer 3 is formed on the soft magnetic underlayer 2. The orientation control layer 3 controls the orientation of the perpendicular magnetic layer 4 which is a layer immediately above, and refines the crystal grains of the perpendicular magnetic layer 4 to improve the recording / reproducing characteristics. As shown below, the alignment control layer 3 includes a first film formation step for forming the first alignment control layer 3a and a second film formation for forming the second alignment control layer 3b on the first alignment control layer 3a. It forms by performing a film-forming process.

(First film formation step)
The first film formation step is a step of forming the first orientation control layer 3a by a reactive sputtering method using a target containing a CoCr alloy and using a sputtering gas containing nitrogen. In the first film formation step, since the sputtering gas contains nitrogen, when forming the first orientation control layer 3a, the target surface comes into contact with nitrogen, and the CoCr alloy contained in the target reacts with nitrogen. To do. Further, when the first orientation control layer 3a is formed, sputtered particles flying when the target is sputtered are combined with nitrogen in the sputtering gas. As a result, by performing the first film forming step, it is made of a CoCr alloy containing nitrogen, and as shown in FIG. 2, a crystal serving as a nucleus is grown, and a fine dome-shaped convex portion is formed on the top. The first orientation control layer 3a including the first columnar crystal S1 and having few voids is formed.

In addition, when a film formed by a reactive sputtering method using a sputtering gas containing nitrogen using a target containing a CoCr alloy was analyzed by SIMS (secondary ion mass spectrometer), it was about several at% in the CoCr alloy. It was confirmed that the film was a film mixed with N of a different concentration. The XPS spectrum confirmed the formation of Cr ₂ N in the CoCr alloy. In this regard, the inventors speculated that Cr ₂ N was formed in the CoCr alloy by the manufacturing method of the present invention, thereby causing the CoCr alloy to be microcrystallized and forming an orientation control layer with extremely low void content. ing.

In the first film forming step, it is preferable to use a gas containing an inert gas and nitrogen in the range of 0.1% by volume to 20% by volume of the inert gas as the sputtering gas. It is more preferable to use one containing nitrogen within the range of 10% by volume to 10% by volume. Note that argon, neon, xenon, or the like can be used as an inert gas contained in the sputtering gas.
In the first film formation step, the pressure of the sputtering gas is preferably in the range of 0.1 Pa to 10 Pa, and more preferably in the range of 0.5 Pa to 5 Pa.

When the nitrogen content of the sputtering gas is less than 0.1% by volume of the inert gas and / or the pressure of the sputtering gas is less than 0.1 Pa, the reaction between the CoCr alloy target and nitrogen becomes insufficient, Since the top of the first columnar crystal S1 is less likely to have a good dome shape, the orientation of the first orientation control layer 3a is lowered, and the effect of miniaturizing the magnetic particles constituting the perpendicular magnetic layer 4 by the orientation control layer 3 is obtained. There is a risk of becoming insufficient.
Further, when the nitrogen content of the sputtering gas exceeds 20% by volume of the inert gas and / or the pressure of the sputtering gas exceeds 10 Pa, the crystallinity of the first orientation control layer 3a is lowered and the S / N ratio is reduced. And the number of voids in the first orientation control layer 3a increases, and the impact resistance of the surface of the magnetic recording medium may be insufficient.

The CoCr alloy contained in the target used in the first film forming step preferably contains Co in a range of 55 at% to 95 at% and Cr in a range of 45 at% to 5 at%. By using a target including a CoCr alloy having such a composition, the first columnar crystal S1 having a dome-shaped convex portion at the top can be easily formed. Also, by setting the amount of Co contained in the CoCr alloy to 55 at% or more, the first orientation control layer 3a imparted with sufficient magnetism can be obtained, and the magnetic coupling between the magnetic head and the soft magnetic underlayer 2 is achieved. A magnetic recording medium having high overwrite characteristics (OW characteristics) can be obtained. Further, by setting the amount of Cr contained in the CoCr alloy to 5 at% or more, Cr ₂ N can be formed in the CoCr alloy and voids in the CoCr alloy can be reduced.

  Moreover, the CoCr alloy contained in the target contains 1 at% to 10 at% of one or more elements selected from Pt, B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re. It is preferable that it is included within the range. Thereby, the miniaturization of the columnar crystals 3a included in the first orientation control layer 3a can be promoted. As a result, the density of the columnar crystals S2 and S3 contained in the second orientation control layer 3b and the perpendicular magnetic layer 4 formed on the first orientation control layer 3a can be increased, and higher density recording can be performed. Can be obtained.

If the content of the element contained in the CoCr alloy is less than 1 at%, the effect of promoting the refinement of the columnar crystals 3a, S2, and S3 may not be sufficiently obtained. Further, if the content of the element contained in the CoCr alloy exceeds 10 at%, the contents of Co and Cr are relatively decreased, and it is difficult to form Cr ₂ N in the CoCr alloy.

  The thickness of the first orientation control layer 3a is not limited, but is preferably 5 nm or more so that the top of the first columnar crystal S1 has a good dome shape. However, if the orientation control layer 3 becomes too thick, the magnetic coupling between the magnetic head and the soft magnetic underlayer 2 becomes weak, and the OW characteristics deteriorate. Therefore, the thickness of the first orientation control layer 3a is more preferably in the range of 10 nm to 20 nm.

(Second film formation step)
The second film formation step is a step of forming the second alignment control layer 3b made of Ru or Ru alloy on the first alignment control layer 3a by using a sputtering method. In the present embodiment, the first orientation control layer 3a including the fine first columnar crystal S1 having a dome-like convex portion at the top is formed by growing a crystal serving as a nucleus in the first film forming step. By performing the second film-forming step, as shown in FIG. 2, it grows on the projections of the columnar crystals S1 of the first orientation control layer 3a and along with the crystal grains constituting the first orientation control layer 3a in the thickness direction. The second fine columnar crystals S2 that are continuous with each other grow. Therefore, by performing the second film forming step, as shown in FIG. 2, the crystal which is the nucleus of the first columnar crystal S1 of the first orientation control layer 3a is continuous in the thickness direction, and the dome-shaped convex portion is formed at the top. A second orientation control layer 3b including the fine second columnar crystal S2 having the following is formed.

  Further, as described above, since the first alignment control layer 3a with few voids is formed in the first film formation step, the first alignment control layer 3a is changed to the second alignment control layer 3b in the second film formation step. The number of voids formed by taking over is reduced. As a result, the orientation control layer 3 formed by the manufacturing method of the present embodiment has a very small void content as a whole.

In the second film forming step, for example, an inert gas such as argon, neon, or xenon is used as the sputtering gas.
In the second film formation step, it is preferable that the pressure of the sputtering gas is equal to or higher than the first film formation step and in the range of 5 Pa to 18 Pa. By setting the pressure of the sputtering gas in the second film-forming step within the above range, it is even easier to continue the crystal that becomes the nucleus of the first columnar crystal S1 in the thickness direction and to have a dome-shaped convex portion at the top. The second orientation control layer 3b including the two columnar crystals S2 can be formed.

  When the pressure of the sputtering gas in the second film forming step is less than the above range, the crystal particles of the perpendicular magnetic layer 4 grown on the orientation control layer 3 are separated, and the magnetic particles of the perpendicular magnetic layer are refined. There is a possibility that the effect cannot be obtained sufficiently and a good S / N ratio and thermal fluctuation characteristics cannot be obtained. When the pressure of the sputtering gas in the second film forming step exceeds the above range, the hardness of the second orientation control layer 3b becomes insufficient, and the pressure of the sputtering gas in the first film forming step exceeds 10 Pa. Similarly to the above, the crystallinity of the second orientation control layer 3b is lowered and the S / N ratio is lowered.

As the Ru alloy constituting the second orientation control layer 3b, there is an alloy having a granular structure in which an oxide such as SiO ₂ , Cr ₂ O ₃ , or TiO ₂ is added to Ru in addition to RuCo and RuFe.

  The layer thickness of the second orientation control layer 3b is not limited, but is preferably 7 nm or more. If the thickness of the second orientation control layer 3b is less than the above range, the orientation of the perpendicular magnetic layer 4 by the orientation control layer 3 is enhanced, and the effect of miniaturizing the magnetic particles constituting the perpendicular magnetic layer 4 becomes insufficient. In some cases, a good S / N ratio cannot be obtained.

In the present embodiment, the case where the orientation control layer 3 is composed of two layers of the first orientation control layer 3a and the second orientation control layer 3b has been described as an example. However, the first orientation control layer 3a is described. One or both of the second alignment control layer 3b and the second alignment control layer 3b may be composed of three or more layers.
Here, the relationship between the crystal grains constituting the orientation control layer and the magnetic grains constituting the perpendicular magnetic layer in the magnetic recording medium produced by the production method of the present embodiment will be described with reference to FIG.

As shown in FIG. 2, an uneven surface S1a is formed on the first orientation control layer 3a, with the top of the columnar crystals S1 constituting the first orientation control layer 3a having a dome-like convexity. On the uneven surface S1a of the first orientation control layer 3a, crystal grains constituting the second orientation control layer 3b grow in the thickness direction from the uneven surface S1a as columnar crystals S2. On the second orientation control layer 3b, an uneven surface S2a is formed with the top of the columnar crystal S2 constituting the second orientation control layer 3b having a dome-like projection. Then, on the columnar crystals S2 constituting the second orientation control layer 3b, the crystal grains of the perpendicular magnetic layer 4 become columnar crystals S3 and grow in the thickness direction. In the present embodiment, the crystal grains of the perpendicular magnetic layer 4 are grown on the dome-shaped protrusions of the second orientation control layer 3b, whereby the separation of the grown crystal grains of the perpendicular magnetic layer 4 is promoted. Crystal grains of the magnetic layer 4 are isolated and grown in a columnar shape.
As described above, even when the nonmagnetic underlayer 8 is provided between the second orientation control layer 3b and the perpendicular magnetic layer 4, the columnar crystal in which the nonmagnetic underlayer 8 is grown perpendicular to the substrate surface. Therefore, this columnar crystal is continuous from the second orientation control layer 3b to the perpendicular magnetic layer 4.

  Thus, in the magnetic recording medium of the present embodiment, the columnar crystal S2 of the second orientation control layer 3b and the columnar crystal S3 of the perpendicular magnetic layer 4 are continuously formed on the columnar crystal S1 of the first orientation control layer 3a. Epitaxially grown as crystals. In the present embodiment, as shown in FIG. 1, the perpendicular magnetic layer 4 is multilayered. Crystal grains constituting each layer of the multilayered perpendicular magnetic layer 4 form a continuous columnar crystal from the orientation control layer 3 to the uppermost perpendicular magnetic layer, and repeat epitaxial growth.

Therefore, in the present embodiment, as the first orientation control layer 3a, the one containing the columnar crystal S1 composed of the refined crystal particles is formed, so that the columnar shape is continuously formed in the thickness direction from the top of the columnar crystal S1. The columnar crystals S2 of the second orientation control layer 3b and the columnar crystals S3 of the multilayered perpendicular magnetic layer 4 are also refined.
In the present embodiment, the columnar crystals S1 with few voids are formed between the columnar crystals, so that the columnar crystals S2 of the second orientation control layer 3b and the columnar crystals S3 of the multilayered perpendicular magnetic layer 4 are also obtained. A thing with few voids is formed between columnar crystals.

"Nonmagnetic underlayer"
Next, as shown in FIG. 1, a nonmagnetic underlayer 8 is formed on the orientation control layer 3. The method for forming the nonmagnetic underlayer 8 is not particularly limited, and for example, a sputtering method can be used.
The nonmagnetic underlayer 8 is formed on the second orientation control layer 3b of the orientation control layer 3 as columnar crystals continuous with the columnar crystals S1 and S2 of the first orientation control layer 3a and the second orientation control layer 3b. Epitaxially grown.

The nonmagnetic underlayer 8 is preferably provided between the orientation control layer 3 and the perpendicular magnetic layer 4, but may not be provided. In the initial part of the perpendicular magnetic layer 4 immediately above the orientation control layer 3, disorder of crystal growth that causes noise is likely to occur. By providing the nonmagnetic underlayer 8, noise can be suppressed.
The thickness of the nonmagnetic underlayer 8 is preferably 0.2 nm or more and 3 nm or less. If the thickness of the nonmagnetic underlayer 8 exceeds 3 nm, Hc and Hn decrease, which is not preferable.

The nonmagnetic underlayer 8 is preferably made of a material containing Cr and an oxide. The Cr content is preferably 25 at% (atomic%) or more and 50 at% or less. As the oxide, for example, oxides such as Cr, Si, Ta, Al, Ti, Mg, and Co are preferably used, and among them, TiO ₂ , Cr ₂ O ₃ , SiO _{2, and the} like are preferably used. it can. The content of the oxide is preferably 3 mol% or more and 18 mol% or less with respect to the total amount of mol calculated as one compound, for example, an alloy such as Co, Cr, and Pt constituting the magnetic particles.

The nonmagnetic underlayer 8 is preferably made of a complex oxide to which two or more kinds of oxides are added. Among these, Cr ₂ O ₃ —SiO ₂ , Cr ₂ O ₃ —TiO ₂ , Cr ₂ O ₃ —SiO ₂ —TiO _{2 and the} like can be preferably used. Furthermore, CoCr—SiO ₂ , CoCr—TiO ₂ , CoCr—Cr ₂ O ₃ —SiO ₂ , CoCr—TiO ₂ —Cr ₂ O ₃ , CoCr—Cr ₂ O ₃ —TiO ₂ —SiO ₂ or the like is preferably used. Can do. Further, Pt may be added from the viewpoint of crystal growth.

"Perpendicular magnetic layer"
Next, as shown in FIG. 1, the perpendicular magnetic layer 4 is formed on the nonmagnetic underlayer 8. The method for forming the perpendicular magnetic layer 4 is not particularly limited, and for example, a sputtering method can be used.
The perpendicular magnetic layer 4 has an easy axis of magnetization oriented perpendicular to the nonmagnetic substrate 1. The perpendicular magnetic layer 4 shown in FIG. 1 includes three layers from the non-magnetic substrate 1 side: a lower magnetic layer 4a, an intermediate magnetic layer 4b, and an upper magnetic layer 4c.

In the magnetic recording medium shown in FIG. 1, a lower nonmagnetic layer 7a is included between the lower magnetic layer 4a and the intermediate magnetic layer 4b, and between the intermediate magnetic layer 4b and the upper magnetic layer 4c. By including the upper nonmagnetic layer 7b, the magnetic layers 4a to 4c and the nonmagnetic layers 7a and 7b are alternately stacked.
The crystal grains constituting each of the magnetic layers 4a to 4c and the nonmagnetic layers 7a and 7b are non-crystalline as columnar crystals that are continuous with the columnar crystals of the first orientation control layer 3a and the second orientation control layer 3b of the orientation control layer 3. Epitaxially grown on the magnetic underlayer 8.

The magnetic layer 4a constituting the perpendicular magnetic layer 4 is a magnetic layer having a granular structure, and preferably includes magnetic particles containing Co, Cr, and Pt (crystal particles having magnetism) and an oxide.
The content of Cr in the magnetic layer 4a is preferably 4 at% or more and 19 at% or less (more preferably 6 at% or more and 17 at% or less). When the content of Cr in the magnetic layer 4a is in the above range, the magnetic anisotropy constant Ku of the magnetic particles is not lowered too much, and high magnetization is maintained, resulting in recording / reproduction characteristics suitable for high-density recording and Sufficient thermal fluctuation characteristics can be obtained.

  On the other hand, when the content of Cr in the magnetic layer 4a exceeds the above range, the magnetic anisotropy constant Ku of the magnetic particles decreases, so that the thermal fluctuation characteristics deteriorate, and the crystallinity and orientation of the magnetic particles. As the result of deterioration of the recording / reproducing characteristics, it is not preferable. In addition, when the Cr content is less than the above range, the magnetic anisotropy constant Ku of the magnetic particles becomes high, so that the perpendicular coercive force becomes too high, and the magnetic head is sufficient for recording data. This is not preferable because writing cannot be performed, and as a result, recording characteristics (OW) not suitable for high-density recording are obtained.

  The content of Pt in the magnetic layer 4a is preferably 8 at% or more and 20 at% or less. If the Pt content is less than 8 at%, the magnetic anisotropy constant Ku necessary for the perpendicular magnetic layer 4 to obtain thermal fluctuation characteristics suitable for high-density recording cannot be obtained, which is not preferable. If the Pt content exceeds 20 at%, stacking faults are generated inside the magnetic particles, and as a result, the magnetic anisotropy constant Ku is lowered. Moreover, when the Pt content exceeds the above range, an fcc structure layer is formed in the magnetic particles, and the crystallinity and orientation may be impaired. Therefore, in order to obtain thermal fluctuation characteristics and recording / reproduction characteristics suitable for high-density recording, it is preferable to set the Pt content in the magnetic layer 4a within the above range.

  In addition to Co, Cr, and Pt, the magnetic particles of the magnetic layer 4a include one or more elements selected from B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re. It may be included. By including the above elements, it is possible to promote miniaturization of magnetic particles or improve crystallinity and orientation, and to obtain recording / reproducing characteristics and thermal fluctuation characteristics suitable for higher density recording.

  Moreover, it is preferable that the total content of the above-mentioned other elements of Co, Cr, and Pt contained in the magnetic particles is 8 at% or less. If the total content of the above elements exceeds 8 at%, a phase other than the hcp phase is formed in the magnetic particles, so that the crystallinity and orientation of the magnetic particles are disturbed, resulting in recording / reproduction suitable for high-density recording. It is not preferable because characteristics and thermal fluctuation characteristics cannot be obtained.

As a material suitable for the magnetic layer 4a, for example, 90 (Co14Cr18Pt) -10 (SiO ₂ ) {Cr content 14at%, Pt content 18at%, molar concentration calculated as one compound with magnetic particles composed of the remaining Co. Is 90 mol%, the oxide composition of SiO ₂ is 10 mol%}, 92 (Co10Cr16Pt) -8 (SiO ₂ ), 94 (Co8Cr14Pt4Nb) -6 (Cr ₂ O ₃ ), and (CoCrPt)-(Ta ₂ O _{5), (CoCrPt) - (} Cr 2 O 3) - (TiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2), (CoCrPt) - (Cr 2 O 3) - (SiO 2) _{- (TiO 2), (CoCrPtMo} ) - (TiO), (CoCrPtW) - (TiO 2), (CoCrPtB) - (Al 2 Examples thereof include compositions such as (O ₃ ), (CoCrPtTaNd)-(MgO), (CoCrPtBCu)-(Y ₂ O ₃ ), (CoCrPtRu)-(SiO ₂ ).

  Similarly to the magnetic layer 4a, the magnetic layer 4b constituting the perpendicular magnetic layer 4 is a magnetic layer having a granular structure, and includes magnetic particles containing Co, Cr, and Pt (crystal grains having magnetism) and an oxide. It is preferable.

  The magnetic layer 4c constituting the perpendicular magnetic layer 4 preferably includes magnetic particles containing Co and Cr (crystal particles having magnetism) and does not contain an oxide. The magnetic particles in the magnetic layer 4c are preferably those grown epitaxially in a columnar shape from the magnetic particles in the magnetic layer 4a. In this case, it is preferable that the magnetic particles of the magnetic layers 4a to 4c are epitaxially grown in a columnar shape corresponding to one to one in each layer. Further, since the magnetic particles of the magnetic layer 4b are epitaxially grown from the magnetic particles in the magnetic layer 4a, the magnetic particles of the magnetic layer 4b are miniaturized and the crystallinity and orientation are further improved.

  The content of Cr in the magnetic layer 4c is preferably 10 at% or more and 24 at% or less. By setting the Cr content in the above range, it is possible to sufficiently ensure output during data reproduction and to obtain better thermal fluctuation characteristics. On the other hand, when the content of Cr exceeds the above range, the magnetization of the magnetic layer 4c becomes too small, which is not preferable. In addition, when the Cr content is less than the above range, magnetic particles are not sufficiently separated and refined, noise during recording / reproduction increases, and a signal / noise ratio (S / S) suitable for high-density recording. N ratio) is not obtained, which is not preferable.

  When the magnetic particles constituting the magnetic layer 4c are a material containing Pt in addition to Co and Cr, the content of Pt in the magnetic layer 4c is preferably 8 at% or more and 20 at% or less. When the Pt content is in the above range, a sufficient coercive force suitable for high recording density can be obtained, and a high reproduction output during recording / reproduction can be maintained, resulting in recording / reproduction characteristics suitable for high-density recording. And thermal fluctuation characteristics are obtained. On the other hand, if the content of Pt in the magnetic layer 4c exceeds the above range, an fcc-structured phase is formed in the magnetic layer 4c, and crystallinity and orientation may be impaired. If the Pt content is less than the above range, the magnetic anisotropy constant Ku for obtaining thermal fluctuation characteristics suitable for high-density recording may not be obtained.

  The magnetic particles constituting the magnetic layer 4c are non-granular magnetic layers, and besides Co, Cr, Pt, B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, Re, One or more elements selected from Mn can be included. By including the above elements, it is possible to promote miniaturization of magnetic particles or improve crystallinity and orientation, and to obtain recording / reproducing characteristics and thermal fluctuation characteristics suitable for higher density recording.

Moreover, it is preferable that the total content of Co, Cr, and Pt contained in the magnetic particles of the magnetic layer 4c is 16 at% or less. If the total content of the above elements exceeds 16 at%, phases other than the hcp phase are formed in the magnetic particles, so that the crystallinity and orientation of the magnetic particles are disturbed, resulting in recording / reproduction suitable for high-density recording. It is not preferable because characteristics and thermal fluctuation characteristics cannot be obtained.
Examples of suitable materials for the magnetic layer 4c include CoCrPt and CoCrPtB. As the CoCrPtB system, the total content of Cr and B is preferably 18 at% or more and 28 at% or less.

  Suitable materials for the magnetic layer 4c include, for example, Co14-24Cr8-22Pt {Cr content 14-24at%, Pt content 8-22at%, balance Co} in CoCrPt series, Co10-24Cr8 ~ in CoCrPtB series. 22Pt0-16B {Cr content: 10-24at%, Pt content: 8-22at%, B content: 0-16at%, balance Co} is preferable. As other systems, in CoCrPtTa system, Co10-24Cr8-22Pt1-5Ta {Cr content 10-24at%, Pt content 8-22at%, Ta content 1-5at%, balance Co}, CoCrPtTaB system, In addition to Co10-24Cr8-22Pt1-5Ta1-10B {Cr content 10-24 at%, Pt content 8-22 at%, Ta content 1-5 at%, B content 1-10 at%, balance Co}, Examples of the material include CoCrPtBNd, CoCrPtTaNd, CoCrPtNb, CoCrPtBW, CoCrPtMo, CoCrPtCuRu, and CoCrPtRe.

The perpendicular coercive force (Hc) of the perpendicular magnetic layer 4 is preferably 3000 [Oe] or more. When the coercive force is less than 3000 [Oe], the recording / reproducing characteristics, particularly the frequency characteristics, are deteriorated, and the thermal fluctuation characteristics are also deteriorated, which is not preferable as a high-density recording medium.
The reverse magnetic domain nucleation magnetic field (-Hn) of the perpendicular magnetic layer 4 is preferably 1500 [Oe] or more. When the reverse domain nucleation magnetic field (-Hn) is less than 1500 [Oe], the thermal fluctuation resistance is poor, which is not preferable.

The average particle diameter of the magnetic particles constituting the perpendicular magnetic layer 4 is preferably 3 to 12 nm. The average particle diameter of the magnetic particles can be obtained, for example, by observing the perpendicular magnetic layer 4 with a TEM (transmission electron microscope) and image-processing the observed image.
The thickness of the perpendicular magnetic layer 4 is preferably 5 to 30 nm. If the thickness of the perpendicular magnetic layer 4 is less than the above, sufficient reproduction output cannot be obtained, and the thermal fluctuation characteristics also deteriorate. On the other hand, if the thickness of the perpendicular magnetic layer 4 exceeds the above range, the magnetic particles in the perpendicular magnetic layer 4 are enlarged and noise during recording / reproduction increases, and the signal / noise ratio (S / N ratio) This is not preferable because recording / reproduction characteristics represented by recording characteristics (OW) deteriorate.

  In the present invention, among the plurality of magnetic layers 4a, 4b, 4c constituting the perpendicular magnetic layer 4, the magnetic layer 4a on the nonmagnetic substrate 1 side is a magnetic layer having a granular structure, and the magnetic layer 4c on the protective layer 5 side is A magnetic layer having a non-granular structure containing no oxide is preferable. With this configuration, it is possible to more easily control and adjust each characteristic such as the thermal fluctuation characteristic, recording characteristic (OW), and S / N ratio of the magnetic recording medium.

  In the present invention, the perpendicular magnetic layer 4 can be composed of four or more magnetic layers. For example, in addition to the magnetic layers 4a and 4b, a magnetic layer having a granular structure may be formed, and a magnetic layer 4c containing no oxide may be provided on the three magnetic layers having the granular structure. However, the magnetic layer 4c not containing an oxide may have a two-layer structure provided on the magnetic layers 4a and 4b.

Further, in the present invention, as shown in FIG. 1, it is preferable to provide a nonmagnetic layer 7 (indicated by reference numerals 7a and 7b in FIG. 1) between a plurality of magnetic layers constituting the perpendicular magnetic layer 4. The method for forming the nonmagnetic layer 7 is not particularly limited, and for example, a sputtering method can be used.
By providing the nonmagnetic layer 7 with an appropriate thickness, magnetization reversal of individual films can be facilitated, and dispersion of magnetization reversal of the entire magnetic particles can be reduced. As a result, the S / N ratio can be further improved.
The thickness of the nonmagnetic layer 7 is set in a range in which the magnetostatic coupling of each layer constituting the perpendicular magnetic layer 4 is not completely cut, and specifically, 0.1 nm or more and 2 nm or less (more preferably 0.1 or more and 0.8 nm). Or less).

"Protective layer"
Next, the protective layer 5 is formed on the perpendicular magnetic layer 4 by using, for example, a CVD (chemical vapor deposition) method.
The protective layer 5 prevents corrosion of the perpendicular magnetic layer 4 and prevents damage to the medium surface when the magnetic head accidentally contacts the magnetic recording medium. As the protective layer 5, a conventionally known material can be used. For example, a material containing C, SiO ₂ , or ZrO ₂ can be used. The thickness of the protective layer 5 is preferably 1 to 10 nm from the viewpoint of high recording density because the distance between the magnetic head and the magnetic recording medium can be reduced.

"Lubrication layer"
Next, the lubricating layer 6 is formed on the protective layer 5 by using, for example, a dipping method.
As the lubricating layer 6, it is preferable to use a lubricant such as perfluoropolyether, fluorinated alcohol, or fluorinated carboxylic acid.
Through the above steps, the magnetic recording medium shown in FIG. 1 is obtained.

  In the method for manufacturing a magnetic recording medium of the present embodiment, a first orientation control layer 3a is formed by a reactive sputtering method using a sputtering gas containing nitrogen using a target containing a CoCr alloy, and the first orientation control layer 3a. On top of this, the orientation control layer 3 is formed by forming the second orientation control layer 3b made of Ru or Ru alloy by using a sputtering method. Therefore, the columnar crystal S1 having a dome-like projection on the top, The orientation control layer 3 having excellent vertical orientation including S2 can be formed. Therefore, according to the method of manufacturing the magnetic recording medium of the present embodiment, the perpendicular magnetic layer 4 including the columnar crystals S3 continuous in the thickness direction with the columnar crystals S1 and S2 included in the orientation control layer 3 on the orientation control layer 3. And a magnetic recording medium suitable for high recording density can be obtained. Furthermore, according to the method for manufacturing a magnetic recording medium of the present invention, since the orientation control layer 3 with few voids is formed, a magnetic recording medium having excellent impact resistance can be obtained.

(Magnetic recording / reproducing device)
FIG. 3 is a perspective view showing an example of the magnetic recording / reproducing apparatus of the present invention.
This magnetic recording / reproducing apparatus includes the magnetic recording medium 50 shown in FIG. 1 manufactured by using the manufacturing method described above, a medium driving unit 51 that rotationally drives the magnetic recording medium 50, and information recording / reproducing on the magnetic recording medium 50. A magnetic head 52 for performing the above, a head drive unit 53 for moving the magnetic head 52 relative to the magnetic recording medium 50, and a recording / reproducing signal processing system 54.

The recording / reproducing signal processing system 54 is capable of processing data input from the outside and sending a recording signal to the magnetic head 52, processing a reproducing signal from the magnetic head 52 and sending the data to the outside. .
As the magnetic head 52, a magnetic head suitable for high recording density having a GMR element utilizing a giant magnetoresistance effect (GMR) as a reproducing element can be used.

  The magnetic recording / reproducing apparatus shown in FIG. 3 includes the magnetic recording medium 50 shown in FIG. 1 and the magnetic head 52 for recording / reproducing information with respect to the magnetic recording medium 50. Therefore, the magnetic recording / reproducing apparatus shown in FIG. Therefore, the magnetic recording medium is provided with an excellent signal / noise ratio (S / N ratio), recording characteristics (OW), and thermal fluctuation characteristics.

Hereinafter, the effects of the present invention will be made clearer by examples. In addition, this invention is not limited to a following example, In the range which does not change the summary, it can change suitably and can implement.
Example 1
The magnetic recording medium of Example 1 was manufactured and evaluated by the manufacturing method described below.

First, a cleaned glass substrate (manufactured by Konica Minolta, 2.5 inch outer diameter) is housed in a film forming chamber of a DC magnetron sputtering apparatus (C-3040, manufactured by Anelva), and the ultimate vacuum is 1 × 10 ^{−3. The} inside of the deposition chamber was evacuated to ⁵ Pa, and an adhesion layer having a layer thickness of 10 nm was formed on the glass substrate using a Cr target.
On the adhesion layer thus obtained, a target of Co-20Fe-5Zr-5Ta {Fe content 20at%, Zr content 5at%, Ta content 5at%, balance Co} is used at 100 ° C or lower. A soft magnetic layer with a layer thickness of 25 nm is formed at a substrate temperature of 0.1 nm, a Ru layer is formed thereon with a thickness of 0.7 nm, and a soft magnetic layer of Co-20Fe-5Zr-5Ta is formed with a layer thickness of 25 nm. This was formed into a soft magnetic underlayer.

  Next, an orientation control layer was formed on the soft magnetic underlayer by performing the following first film forming process and second film forming process. As the orientation control layer, a first orientation control layer disposed on the soft magnetic underlayer side and a second orientation control layer disposed on the perpendicular magnetic layer side of the first orientation control layer were formed.

(First film formation step)
First, a target made of 73Co22Cr5Mo, a sputtering gas made of a mixed gas of Ar (flow rate 200 sccm) and nitrogen gas (flow rate 10 sccm) is used on the soft magnetic underlayer, the sputtering gas pressure is 0.8 Pa, and the plasma power is 1000 W. A first alignment control layer was formed to a thickness of 15 nm by reactive sputtering.
(Second film formation step)
Next, on the first orientation control layer, a target made of Ru and a sputtering gas made of Ar gas are used to form a second orientation control layer made of Ru with a film thickness of 13 nm by sputtering at a sputtering gas pressure (gas pressure) of 10 Pa. Formed with.

Thereafter, a perpendicular magnetic layer was formed on the orientation control layer.
First, 91 (Co15Cr16Pt) -6 (SiO ₂ ) -3 (TiO ₂ ) {Cr content of 15 at%, Pt content of 16 at%, and the remaining Co is an alloy composed of 91 mol% and SiO ₂ on the orientation control layer. A magnetic layer having a composition of 6 mol% of the product and 3 mol% of the oxide composed of TiO ₂ was formed with a sputtering gas pressure of 2 Pa and a layer thickness of 9 nm.

Next, a nonmagnetic layer made of 88 (Co30Cr) -12 (TiO ₂ ) was formed on the magnetic layer with a layer thickness of 0.3 nm.
Next, a magnetic layer made of 92 (Co11Cr18Pt) -5 (SiO ₂ ) -3 (TiO ₂ ) was formed on the nonmagnetic layer with a sputtering gas pressure of 2 Pa and a layer thickness of 6 nm.
Next, a nonmagnetic layer made of Ru was formed with a layer thickness of 0.3 nm on the magnetic layer.
Next, on the non-magnetic layer, using a target made of Co20Cr14Pt3B {Cr content 20at%, Pt content 14at%, B content 3at%, balance Co}, the sputtering gas pressure is set to 0.6Pa. Was deposited with a layer thickness of 7 nm.

  Next, a protective layer having a thickness of 3.0 nm was formed by a CVD method, and then a lubricating layer made of perfluoropolyether was formed by a dipping method to obtain a magnetic recording medium of Example 1.

(Evaluation of electromagnetic conversion characteristics)
For the magnetic recording medium of Example 1 obtained in this way, using a read / write analyzer RWA1632 and spin stand S1701MP manufactured by GUZIK, USA, the signal / noise ratio (S / N), recording characteristics (recording characteristics) Each evaluation of (OW) was performed. The results are shown in Table 1.

As the magnetic head, a head using a single pole magnetic pole on the writing side and a TMR element on the reading side was used.
The signal / noise ratio (S / N) was measured at a recording density of 750 kFCI.
Regarding the recording characteristics (OW), first, a 750 kFCI signal was written, then a 100 kFCI signal was overwritten, a high frequency component was taken out by a frequency filter, and the data writing ability was evaluated by the residual ratio.

(Evaluation of impact resistance of magnetic recording media)
The scratch resistance of the magnetic recording medium produced in Example 1 was evaluated by the following method using a Kubota Comps SAF tester and a Candela optical surface inspection apparatus (OSA).
That is, at a room temperature, the magnetic recording medium (disk) has a rotational speed of 5000 rpm and an atmospheric pressure of 100 Torr, and is held for 2000 seconds with the head loaded by the SAF tester, and then the number of scratches is counted by OSA. It was. As a result, the scratch count of the magnetic recording medium manufactured in Example 1 was 180.

(Comparative Examples 1-4, Examples 2-3)
Magnetic recording was carried out in the same manner as in Example 1 except that the first orientation control layer was formed by using a target composed of a metal having the composition shown in Table 1 and a sputtering gas with the pressure and film formation method shown in Table 1. A medium was manufactured, and signal / noise ratio (S / N) and recording characteristics (OW) and impact resistance were evaluated in the same manner as in Example 1. The results are shown in Table 1.

As shown in Table 1, in Examples 1 to 3, compared to Comparative Example 1 using a target made of Ru and Comparative Examples 2 to 4 using a sputtering gas not containing nitrogen, the impact resistance evaluation was counted. It was confirmed that the number was small and the impact resistance was excellent. This result is presumed to be due to the small number of voids in the orientation control layer in Examples 1 to 3.
In Examples 1 to 3, the signal / noise ratio (S / N) and the recording characteristics (OW) were also evaluated well.

DESCRIPTION OF SYMBOLS 1 ... Nonmagnetic board | substrate, 2 ... Soft magnetic underlayer, 3 ... Orientation control layer, 3a ... 1st orientation control layer, 3b ... 2nd orientation control layer, 4 ... Perpendicular magnetic layer, 4a, 4b, 4c ... Magnetic layer, DESCRIPTION OF SYMBOLS 5 ... Protective layer, 6 ... Lubricating layer, 7, 7a, 7b ... Non-magnetic layer, 8 ... Non-magnetic underlayer, S1, S2, S3 ... Columnar crystal, S1a ... Uneven surface, 50 ... Magnetic recording medium, 51 ... Medium Drive unit, 52... Magnetic head, 53... Head drive unit, 54.

Claims (7)

On the nonmagnetic substrate, at least a soft magnetic underlayer, an orientation control layer for controlling the orientation of the layer immediately above, and a perpendicular magnetic layer having an easy axis oriented perpendicular to the nonmagnetic substrate, A method of manufacturing a magnetic recording medium formed in this order,
A first film forming step of forming a first orientation control layer by a reactive sputtering method using a sputtering gas containing nitrogen using a target containing a CoCr alloy;
Forming the alignment control layer on the first alignment control layer by performing a second film formation step of forming a second alignment control layer made of Ru or a Ru alloy using a sputtering method ;
Examples CoCr alloy includes Co in the range of 55at% ~95at%, the method of manufacturing a magnetic recording medium characterized Rukoto with those containing Cr in a range of 45at% ~5at%.   The first film forming step is characterized in that a gas containing an inert gas and nitrogen in a range of 0.1 volume% to 20 volume% of the inert gas is used as the sputtering gas. 2. A method for producing a magnetic recording medium according to 1.   3. The method of manufacturing a magnetic recording medium according to claim 1, wherein in the first film formation step, the pressure of the sputtering gas is set within a range of 0.1 Pa to 10 Pa. 4.   4. The method according to claim 1, wherein, in the second film formation step, the pressure of the sputtering gas is set to be equal to or higher than the first film formation step and within a range of 5 Pa to 18 Pa. 5. A method of manufacturing a magnetic recording medium. In the first film-forming step, a crystal serving as a nucleus is grown, and the first orientation control layer including a first columnar crystal having a dome-shaped convex portion at the top is formed.
In the second film forming step, the second orientation control layer including a second columnar crystal that is continuous in a thickness direction with a crystal serving as a nucleus of the first columnar crystal and has a dome-shaped convex portion at the top is formed. The method for manufacturing a magnetic recording medium according to claim 1, wherein: The CoCr alloy contains one or more elements selected from Pt, B, Ta, Mo, Cu, Nd, W, Nb, Sm, Tb, Ru, and Re in a range of 1 at% to 10 at%. the method of manufacturing a magnetic recording medium according to any one of claims 1 to 5, characterized in that. A magnetic recording comprising: a magnetic recording medium manufactured by using the method according to any one of claims 1 to 6 ; and a magnetic head for recording and reproducing information on the magnetic recording medium. Playback device.

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