JP2011096334A - 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 comprehensively enhancing coercive force Hc, a reverse magnetic domain nucleation magnetic field Hn and an SNR. <P>SOLUTION: The method for manufacturing the perpendicular magnetic recording medium includes a soft magnetic layer film-depositing step of film-depositing a soft magnetic layer 130 on a substrate 110, a heating step of subjecting the substrate after the soft magnetic layer is film-deposited to heating treatment, a front underlayer film-depositing step of film-depositing a front underlayer 140 consisting essentially of Ni and containing at least 1 to 5 at% B on the soft magnetic layer in a temperature rising state by the heating treatment, an underlayer film-depositing step of film-depositing an underlayer 150 consisting essentially of Ru on the front underlayer and a main recording layer film-depositing step of film-depositing a main recording layer 160 comprising magnetic particles consisting essentially of a CoCrPt alloy and a non-magnetic grain boundary part consisting essentially of an oxide on the underlayer. <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 demanded for a 2.5-inch diameter perpendicular magnetic recording medium used for HDDs and the like. In order to meet such a demand, 500 GB / it is necessary to realize an information recording density exceeding Inch ^2.

  As important factors for increasing the recording density of the perpendicular magnetic recording medium, improvement in TPI (Tracks per Inch) by narrowing the track width and signal-to-noise ratio (SNR: when improving BPI (Bits per Inch)) Ensuring electromagnetic conversion characteristics such as signal to noise ratio and overwrite characteristics (OW characteristics), and ensuring thermal fluctuation resistance in a state where the recording bit is reduced by the above can be improved. Among these, improvement of SNR under high recording density conditions is important.

  The SNR is improved mainly by reducing the noise in the magnetization transition region at the recording bit boundary. Effective elements for noise reduction include improvement of crystal orientation of the magnetic recording layer and refinement of the particle size of the magnetic particles. Among these, refinement of the grain size is effective for improving the SNR, but on the other hand, the crystal orientation tends to be lowered.

  In order to increase the recording density, it is necessary to narrow the track width. One method for reducing the track width is to increase the coercive force Hc. In order to increase the coercive force Hc, it is conceivable to first simply increase the thickness of the magnetic recording layer. In this case, however, there is a trade-off that the SNR generally decreases. As another means for improving the coercive force Hc, it is conceivable to improve the crystal orientation of the magnetic particles.

  Conventionally, in order to improve the crystal orientation of the magnetic recording layer, an underlayer (sometimes referred to as an intermediate layer) made of Ru or the like has been provided (for example, Patent Document 1), and further below the front of the fcc structure. A configuration in which an underlayer (sometimes referred to as a seed layer) is provided is known (for example, Patent Document 2). In Patent Document 2, the soft magnetic film has an amorphous structure, the base film (corresponding to the previous base layer) is made of a NiW alloy, and the intermediate film (corresponding to the base layer) is made of a Ru alloy. In addition, it is described that a magnetic recording medium capable of recording / reproducing high-density information, a manufacturing method thereof, and a magnetic recording / reproducing apparatus can be provided. Furthermore, it is known that the addition of B to the pre-underlayer made of a NiW alloy can promote the refinement of crystal grains in the pre-underlayer, and consequently magnetic particles in the recording layer (also referred to as a magnetic recording layer). (For example, patent document 3).

Japanese Patent Laid-Open No. 7-334832 JP 2007-179598 A JP 2009-110606 A

  Magnetic recording media exceeding 320 GByte / platter, which has been required in recent years, achieves a narrower track width than conventional 250 GByte / platter magnetic recording media, achieves high SNR, and ensures thermal fluctuation resistance. There is a need to. As a guideline for ensuring thermal fluctuation resistance, Hc may be kept at least 5000 [Oe] or more.

  Furthermore, with the recent increase in recording density, it is said to be a so-called high-temperature fringe (writing fringe) in which a signal of an adjacent track is rewritten when a signal is written to a certain track under a temperature rising condition of about 60 ° C. The phenomenon began to occur. When this phenomenon occurs, the track width must be increased, and consequently the TPI cannot be increased. In order to increase the high temperature fringe resistance, it is necessary to secure a reverse domain nucleation magnetic field Hn of a certain value or more. As a guide, Hn may be set to −2400 [Oe] or less.

  However, when a high recording density of 320 GB / P level is targeted, adding B to the pre-underlayer as in Patent Document 3 promotes the miniaturization of magnetic particles, but the SNR improves, but Hc and Hn, etc. It has been found that it is difficult to secure a narrow track width, thermal fluctuation resistance, and high-temperature fringe resistance because the amount of decrease in magnetostatic characteristics is large.

  An object of the present invention is to solve the above-mentioned problems, and while maintaining thermal fluctuation resistance and high-temperature fringe resistance, it is possible to secure a high SNR in a narrow track width and achieve further higher recording density. An object of the present invention is to provide a method for manufacturing a perpendicular magnetic recording medium.

  As a result of extensive studies by the inventors to solve the above-mentioned problems, the magnetostatic property is deteriorated when B is added to the previous underlayer. It was thought that this was because the orientation deteriorated. In addition, it was considered that the deterioration of the crystal orientation was greatly influenced by B existing in the grains. Therefore, it was thought that if the size could be improved by adding B and the crystal orientation could be improved, the SNR could be improved without deteriorating the magnetostatic characteristics. Recalling that crystal orientation can be improved by heating before film formation, the present invention has been completed by further research.

  In order to solve the above problems, a typical configuration of a method for manufacturing a perpendicular magnetic recording medium according to the present invention includes a soft magnetic layer forming process for forming a soft magnetic layer on a substrate, and a soft magnetic layer forming process. A heating step of performing heat treatment on the subsequent substrate, and a pre-underlayer containing Ni as a main component and containing at least 1 to 5 at% on the soft magnetic layer in a state where the temperature has been raised by the heat treatment A pre-underlayer forming step, a underlayer forming step of forming a base layer containing Ru as a main component above the pre-underlayer, and magnetic particles containing a CoCrPt alloy as a main component over the base layer; And a main recording layer forming step of forming a main recording layer composed of a nonmagnetic grain boundary portion mainly composed of an oxide.

  According to the said structure, refinement | miniaturization of a crystal grain can be accelerated | stimulated by containing B in the front ground layer which has Ni alloy as a main component, and SNR can be aimed at. Then, by providing a heating step for performing heat treatment on the substrate after the soft magnetic layer forming step, that is, before the previous underlayer forming step, the crystal orientation of the previous underlayer can be improved. By these, the fall of the crystal orientation which arises when B is added to the front ground layer can be suppressed by the heating process before the front ground layer film forming process, and the ground layer formed above the front ground layer As a result, high crystal orientation is ensured also in the main recording layer. Therefore, it is possible to improve the SNR while preventing the deterioration of the thermal fluctuation resistance and the high temperature fringe resistance due to the deterioration of the coercive force Hc and the reverse domain nucleation magnetic field Hn, thereby achieving further higher recording density of the perpendicular magnetic recording medium. It becomes possible.

  Here, it is speculated that the improvement of the crystal orientation by heating is not only the effect of improving the crystallinity by heating but also the effect of promoting the discharge of B from the crystal grains of the previous underlayer to the grain boundary. . In addition, as a result of the particle size of the pre-underlayer being more precisely controlled by the effect of discharging B to the grain boundary, it is considered that the particle size of the magnetic particles is also controlled and the SNR is further increased.

  Note that if the B content in the pre-underlayer is less than the above lower limit, the refinement of crystal grains may not be sufficiently promoted. On the other hand, if the B content exceeds the upper limit, it is not preferable because the crystal orientation and SNR are significantly lowered even in the presence of heat treatment.

The term “main component” as used in the present application refers to a component that is contained most when the total composition is at% (or mol%). For example, when considering a composition of 90 (70Co-10Cr-20Pt) -10 (SiO ₂ ), it is assumed that the CoCrPt alloy is the main component because it accounts for 90% of the total. Further, since Co accounts for 70% in the CoCrPt alloy, Co is assumed to be the main component of the CoCrPt alloy.

  An amorphous metal layer forming step of forming an amorphous metal layer between the soft magnetic layer and the pre-underlayer may be further included. Thereby, since the substrate surface roughness before film formation of the pre-underlayer can be reduced, the crystal orientation of the pre-underlayer can be further increased and high SNR can be achieved.

  Also, an auxiliary recording layer film forming step for forming an auxiliary recording layer made of a material containing CoCrPt as a main component after the main recording layer film forming step, and a substrate is subjected to heat treatment after the auxiliary recording layer film forming step. It is preferable to further include a second heating step and a protective layer film forming step of forming a protective layer mainly composed of carbon by a CVD method after the second heating step.

  According to the above configuration, the heat treatment of the substrate is performed twice: a heating process performed after the soft magnetic layer film forming process and a second heating process performed after the auxiliary recording layer film forming process. As a result, the reliability of the carbon protective film is improved by improving the film quality of the carbon protective film while minimizing the adverse effect on the magnetic characteristics of the main recording layer due to the heat treatment in the second heating process and ensuring a high SNR. Durability, corrosion durability, etc.).

  The substrate temperature after the heating step is preferably 70 to 120 ° C. Thereby, the effect mentioned above can be acquired most suitably. In addition, it is not preferable that the heat treatment temperature is less than the above lower limit value because the effect of the heat treatment cannot be sufficiently obtained. If the heat treatment temperature exceeds the above upper limit, the granular structure of the main recording layer may be disturbed due to an excessive increase in the substrate temperature.

  The underlayer may further contain an oxide. As a result, separation and refinement of Ru crystal grains can be promoted, and further isolation and refinement of the main recording layer can be achieved.

  The main recording layer preferably contains two or more kinds of oxides. By mixing the oxides in this way, even if the substrate is heated by the first heating step, the magnetic particles in the magnetic recording layer are further refined and isolated to improve the SNR and achieve high recording. Densification can be achieved.

  According to the present invention, by maintaining the coercive force Hc and the reverse domain nucleation magnetic field Hn, the thermal fluctuation resistance and the high-temperature fringe resistance are maintained, and a high SNR is secured in a narrow track width, thereby further increasing the recording density. It is possible to provide a perpendicular magnetic recording medium capable of achieving the above.

It is a figure explaining the structure of a perpendicular magnetic recording medium. It is a figure explaining the other 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 for manufacturing perpendicular magnetic recording medium)
FIG. 1 is a diagram for explaining the configuration of a perpendicular magnetic recording medium 100 according to the present embodiment. 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 main recording layer 160, a dividing layer 170, an auxiliary recording layer 180, a protective layer 190, The lubricating layer 200 is used.

  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.

  On the substrate 110, a film is sequentially formed from the adhesion layer 120 to the auxiliary recording layer 180 by a DC magnetron sputtering method, and the protective layer 190 can be formed by a CVD method. Thereafter, the lubricating layer 200 can be formed by a dip coating method. Hereinafter, the configuration of each layer will be described.

  The adhesion layer 120 is formed in contact with the substrate 110 and has a function of increasing the adhesion strength between the soft magnetic layer 130 formed thereon and the substrate 110. The adhesion layer 120 is made of an amorphous (amorphous) alloy such as a CrTi amorphous alloy, a CoW amorphous alloy, a CrW amorphous alloy, a CrTa amorphous alloy, or a CrNb amorphous alloy. A film is preferred. The film thickness of the adhesion layer 120 can be about 2-20 nm, for example. The adhesion layer 120 may be a single layer or may be formed by stacking a plurality of layers.

  The soft magnetic layer 130 is formed on the substrate 110 via the adhesion layer 120 (soft magnetic layer forming step). 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, by interposing a spacer layer made of Ru substantially in the middle of the soft magnetic layer 130, it can be configured to have 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. .

  In the present embodiment, as described above, after the soft magnetic layer 130 is formed, that is, before the pre-underlayer forming process, the substrate 110 is subjected to a heat treatment (heating process; hereinafter referred to as a first heating process). Since the transfer time between the chambers during film formation is 1 to 2 seconds, the pre-underlayer 140 is formed almost at the substrate temperature after the heat treatment (note that the substrate temperature is measured during transfer between the chambers). be able to.). As described above, by forming the pre-underlayer 140 in a state where the temperature is increased by the heat treatment, the crystal orientation of the pre-underlayer 140 can be improved. Therefore, it is possible to suppress a decrease in crystal orientation that occurs when B is added to the pre-underlayer 140, and high crystallinity is also obtained in the underlayer 150 and thus the main recording layer 160 formed above the pre-underlayer 140. Orientation is ensured. As a result, the SNR can be improved while preventing the deterioration of the thermal fluctuation resistance and the high temperature fringe resistance due to the deterioration of the coercive force Hc and the reverse magnetic domain nucleation magnetic field Hn, and the perpendicular magnetic recording medium 100 can be further increased in recording density. Achievement is possible.

  In said 1st heating process, heat processing temperature is adjusted so that it may become 70-120 degreeC. As a result, it is possible to sufficiently improve the crystal orientation of the pre-underlayer 140 while suppressing disturbance of the granular structure of the main recording layer 160 caused by an excessive increase in the substrate temperature, and the above-described effects are most suitably obtained. It becomes possible.

  Note that the perpendicular magnetic recording medium 100 according to the present embodiment may include an amorphous metal layer 138 described below. FIG. 2 is a diagram for explaining another configuration of the perpendicular magnetic recording medium according to the present embodiment. Note that the heat of the first heating step performed before the formation of the amorphous metal layer 138 remains until the next formation of the previous underlayer 140, and can sufficiently affect (obtain the effect). . Note that the first heating step may be performed after the amorphous metal layer 138 is formed.

  The amorphous metal layer 138 is formed between the soft magnetic layer 130 and the pre-underlayer 140 (amorphous metal layer forming step). The amorphous metal layer 138 is an amorphous metal layer, and has a role of reducing the substrate surface roughness before the pre-underlayer 140 is formed. Thereby, the crystal orientation of the pre-underlayer 140 can be further improved. The amorphous metal layer 138 is made of a Cr compound or a Ni compound, and may be made of, for example, CrTa, NiTa, or NiTi. The thickness of the amorphous metal layer 138 is preferably 1 nm to 10 nm. When the thickness of the amorphous metal layer 138 is thinner than 1 nm, the surface roughness may not be reduced. When the amorphous metal layer 138 is thicker than 10 nm, there is a possibility that the distance (magnetic spacing) from the magnetic head to the soft magnetic layer is unnecessarily increased and the overwrite characteristics are deteriorated.

  The pre-underlayer 140 is formed between the soft magnetic layer 130 and the underlayer 150 (pre-underlayer forming step). The pre-underlayer 140 has a function of promoting crystal orientation of the underlayer 150 formed thereabove and a function of controlling a fine structure such as a grain size. The pre-underlayer 140 may have an hcp structure, but preferably has a face-centered cubic structure (fcc structure) oriented so that the (111) plane is parallel to the main surface of the substrate 110. 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.

  In this embodiment, the pre-underlayer 140 contains Ni as a main component and contains 1 to 5 at% of B. For example, the front ground layer 140 is made of NiWB. In addition to NiWB, V, Cr, Mo, Ta, Si, Zr, Al, or the like may be added.

  According to the above configuration, by adding B to the Ni alloy, the crystal grains can be refined and the SNR can be improved. At this time, although the crystal orientation tends to be lowered due to the refinement of crystal grains, the first heating step is provided before the pre-underlayer forming step in the present embodiment. The decline in sex is suppressed. Therefore, high crystal orientation is ensured also in the pre-underlayer 140, and hence in the underlayer 150 and the main recording layer 160, so that the SNR can be improved while maintaining the coercive force Hc and the reverse domain nucleation magnetic field Hn. It is possible to achieve further higher recording density of the perpendicular magnetic recording medium.

  As described above, in the pre-underlayer 140, the B content is preferably 1 to 5 at%. Within these ranges, the effects of the present invention can be suitably obtained. In addition, there exists a possibility that refinement | miniaturization of a crystal grain may not fully be accelerated | stimulated as the content rate of B is less than said lower limit. On the other hand, if the B content exceeds the above upper limit, the crystal orientation and SNR are significantly lowered even in the presence of heat treatment, which is not preferable.

  The underlayer 150 is formed on the previous underlayer (underlayer forming step). The underlayer 150 has an hcp structure, and has a function of promoting the crystal orientation of the magnetic crystal grains of the hcp structure of the main recording layer 160 formed thereabove and a function of controlling a fine structure such as a grain size. In other words, it is a layer that becomes the basis of the granular structure of the main recording layer. 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 under layer 150, the more the crystal orientation of the main recording layer 160 can be improved. Further, by reducing the particle size of the under layer 150, the particle size of the main recording layer can be reduced. It can be miniaturized. 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.

  Furthermore, oxygen or an oxide may be contained in Ru of the base layer 150. As a result, separation and refinement of Ru crystal grains can be promoted, and further isolation and refinement of the main recording layer 160 can be achieved. Note that oxygen may be contained by reactive sputtering, but it is preferable to use a target containing oxygen or oxide when performing sputtering film formation.

  Further, 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 main recording layer 160 is maintained well, It is possible to reduce the particle size of the magnetic particles.

The main recording layer 160 is formed on the base layer 150 (main recording layer forming step). The main recording layer 160 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 material used for the main recording layer 160 described above is an example, and the present invention is not limited to this. 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 (Ta ₂ O). ₅ ) and oxides such as 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 dividing layer 170 is provided between the main recording layer 160 and the auxiliary recording layer 180 and has an effect of adjusting the strength of exchange coupling between these layers. As a result, the strength of the magnetic coupling acting between the main recording layer 160 and the auxiliary recording layer 180 and between the adjacent magnetic particles in the main recording layer 160 can be adjusted, so that thermal fluctuations such as Hc and Hn occur. The recording / reproducing characteristics such as the overwrite characteristic and the SNR characteristic can be improved while maintaining the magnetostatic value related to the durability.

The split layer 170 is preferably a layer mainly composed of Ru or Co having an hcp crystal structure so as not to lower the inheritance of crystal orientation. As the Ru-based material, in addition to Ru, a material obtained by adding other metal element, oxygen, or oxide to Ru can be used. 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 . In addition, although the non-magnetic material is normally used for the dividing layer 170, it may have weak magnetism. In order to obtain good exchange coupling strength, the thickness of the dividing layer 170 is preferably in the range of 0.2 to 1.0 nm.

  The auxiliary recording layer 180 is a magnetic layer that is substantially magnetically continuous in the in-plane direction of the main surface of the substrate. Since the auxiliary recording layer 180 has a magnetic interaction (exchange coupling) with the main recording layer 160, it is possible to adjust the magnetostatic characteristics such as the coercive force Hc and the reverse domain nucleation magnetic field Hn. Therefore, it is intended to improve thermal fluctuation resistance, OW characteristics, and SNR. As a material for the auxiliary recording layer 180, a CoCrPt-based alloy can be used, and an additive such as B, Ta, or Cu may be added. Specifically, CoCrPt, CoCrPtB, CoCrPtTa, CoCrPtCu, CoCrPtCuB, or the like can be used. The film thickness of the auxiliary recording layer 180 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 entire auxiliary recording layer 180 is not necessarily a single magnet but may be partially discontinuous in magnetism. That is, the auxiliary recording layer 180 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 auxiliary recording layer 180 may have a structure in which, for example, Cr is segregated.

  Then, after the main recording layer film forming step, in this embodiment, after the auxiliary recording layer film forming step as described above, immediately before the protective layer film forming step is performed, the substrate 110 is subjected to heat treatment (second heating). Process). Therefore, in the present embodiment, the first heating step and the second heating step are performed twice. Here, since the second heating step is performed after the auxiliary recording layer is formed, disturbance of the granular structure of the main recording layer can be reduced, and a high SNR can be secured.

  The protective layer 190 can be formed by depositing carbon by a CVD method while maintaining a vacuum (protective layer forming step). The protective layer 190 is a layer for protecting the perpendicular magnetic recording medium 100 from the impact and corrosion of the magnetic head. The protective layer 190 can be formed by forming a film containing carbon by a CVD method. In general, carbon film formed by the CVD method has a higher film hardness than that formed by the sputtering method, so that the perpendicular magnetic recording medium 100 can be more effectively protected against the impact from the magnetic head. Is preferred. The film thickness of the protective layer 190 can be 2-6 nm, for example.

  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.

(Example)
In order to confirm the effectiveness of the manufacturing method of the perpendicular magnetic recording medium 100 having the above-described configuration, a description will be given using the following examples and comparative examples.

As Example 1, film formation was sequentially performed on the substrate 110 from the adhesion layer 120 to the auxiliary recording layer 132 in an Ar atmosphere by a DC magnetron sputtering method using a vacuum forming film forming apparatus. 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. After the formation of the soft magnetic layer 130, the first heating step was performed so that the substrate temperature was 75 ° C. For the pre-underlayer 140, Ni-5W-1B was deposited to 8 nm. 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 main recording layer 160, 90 (70Co-10Cr-20Pt ) -10 (Cr 2 O 3) 90 in 3Pa on top was 2nm deposited _{(72Co-10Cr-18Pt) -5} (SiO 2) -5 (TiO 2 ) Was deposited to 12 nm. The dividing layer 170 was formed by depositing 0.3 nm of Ru. The auxiliary recording layer 180 was formed of 6 nm 62Co-18Cr-15Pt-5B. After forming the auxiliary recording layer 180, before forming the protective layer 190, the second heating step was performed so that the substrate temperature was 200 ° C. The protective layer 190 was formed using C ₂ H ₄ by a CVD method, and the surface layer was nitrided. The lubricating layer 200 was formed using PFPE by a dip coating method. Various conditions in the first heating step and the second heating step will be described in detail later.

  FIG. 3 is a diagram for explaining an example and a comparative example. In FIG. 3, the SNR is compared by adjusting the film thickness of the main recording layer 160 so that the track width (MWW: Magnetic Write Width) becomes a substantially constant value. The value of MWW was set to a range applicable to a magnetic recording medium of 320 GByte / platter.

  In FIGS. 3A and 3B, Examples 1 to 3, and Comparative Examples 1 and 2 are obtained by changing the amount of B contained in the front base layer 140 by setting the substrate temperature after the first heating step to 75 ° C. is there. Based on the configuration and manufacturing method of Example 1, Examples 2 and 3 contain 2, 4 at% B, Comparative Example 1 does not contain B, and Comparative Example 2 contains 6 at% B, respectively. In all cases, W was contained at 5 at%, and Ni was reduced as B increased.

  As can be seen from FIG. 3, the SNR improves when the B content increases to 1 at% and 2 at%. This is presumably because the crystal grains of the pre-underlayer 140 were refined by containing B. However, when the B content is 4 at%, the SNR begins to decrease, and at 6 at%, it is lower than when it is not contained. Here, referring to the value of Δθ50, it can be seen that the value tends to increase (the crystal orientation deteriorates) as the B content increases. From this, it is considered that if the B content is too high, the crystal grains of the pre-underlayer 140 are significantly reduced in crystal orientation and SNR even in the presence of heat treatment. This shows that the content of B is preferably 1 to 5 at%.

  Next, in Examples 4 to 8 and Comparative Example 3, on the basis of the configuration of Example 1, the B content of the front ground layer 140 was set to 2 at%, and the temperature of the substrate after the first heating step was changed. Is. In particular, Examples 4 to 8 were those in which the temperature was changed to 70 to 120 ° C, and Comparative Example 3 was not subjected to the first heating (the substrate temperature was estimated to be 50 ° C or less). Even when the temperature after the first heating step was changed, the input power amount in the second heating step was adjusted so that the temperature after the second heating step was 200 ° C.

  As can be seen from FIG. 3, the SNR increases when the temperature after the first heating step is in the range of 70 ° C. to 120 ° C. From this, it can be seen that the substrate temperature after the first heating step is preferably 70 to 120 ° C.

  It can also be seen that the reverse domain nucleation magnetic field Hn tends to increase (the absolute value increases) as the temperature after the first heating is increased from 70 ° C. to 120 ° C. An increase in Hn means that high-temperature fringe resistance is improved.

  Next, in Example 9, in addition to the configuration of Example 1, an amorphous metal layer 138 is formed under the pre-underlayer 140 (see FIG. 2). As the amorphous metal layer 138, Ni-50Ta was formed to a thickness of 5 nm.

  When Example 9 and Example 1 are compared, it can be seen that Δθ50 is significantly reduced and the crystal orientation is improved. Along with this, it can be seen that the SNR is also dramatically improved. This is presumably because the provision of the amorphous metal layer 138 reduces the surface roughness of the substrate before the formation of the pre-underlayer and further improves the crystal orientation of the pre-underlayer 140.

  Here, the coercive force Hc required to satisfy a predetermined thermal fluctuation resistance applicable to a 320 GB / platter magnetic recording medium is 5000 [Oe] or more, and all of the examples and comparative examples satisfy this requirement. It was. Further, the reverse domain nucleation magnetic field Hn required to satisfy the predetermined high-temperature fringe resistance is −2400 [Oe] or less, and all the examples satisfy this, but the comparative examples 2 and 3 satisfy. It wasn't. Therefore, it can be seen that the example is superior in high-temperature fringe resistance than the comparative example. As compared with all the comparative examples, the SNR was improved in all the examples. From these results, it was confirmed that by applying the present invention, high SNR can be obtained in a narrow track width while maintaining thermal fluctuation resistance and high-temperature fringe resistance.

  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.

  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, 138 ... Amorphous metal layer, 140 ... Pre-underlayer, 150 ... Underlayer, 160 ... Main recording layer, 170 ... Minute Fault, 180 ... auxiliary recording layer, 190 ... protective layer, 200 ... lubricating layer

Claims (6)

A soft magnetic layer forming step of forming a soft magnetic layer on the substrate;
A heating step of performing a heat treatment on the substrate after forming the soft magnetic layer;
A pre-underlayer forming step of forming a pre-underlayer containing Ni as a main component and containing at least 1 to 5 at% on the soft magnetic layer in a state where the temperature is increased by heat treatment;
An underlayer film forming step of forming an underlayer mainly composed of Ru above the previous underlayer;
A main recording layer forming step of forming a main recording layer formed of magnetic particles mainly composed of a CoCrPt alloy and a nonmagnetic grain boundary portion mainly composed of an oxide above the underlayer;
A method of manufacturing a perpendicular magnetic recording medium.   2. The perpendicular magnetic recording medium according to claim 1, further comprising an amorphous metal layer forming step of forming an amorphous metal layer between the soft magnetic layer and the pre-underlayer. Production method. An auxiliary recording layer film forming step of forming an auxiliary recording layer made of a material mainly composed of CoCrPt after the main recording layer film forming step;
A second heating step of performing a heat treatment on the substrate after the auxiliary recording layer film forming step;
A protective layer forming step of forming a protective layer mainly composed of carbon by a CVD method after the second heating step;
The method of manufacturing a perpendicular magnetic recording medium according to claim 1, further comprising:   2. The method of manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the substrate temperature after the heating step is 70 to 120 [deg.] C.   The method of manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the underlayer further contains an oxide.   The method of manufacturing a perpendicular magnetic recording medium according to claim 1, wherein the main recording layer includes two or more kinds of oxides.

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