JP2006155844A - Perpendicular magnetic recording medium and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a medium having a high media S/N ratio and excellent corrosion resistance. <P>SOLUTION: In the perpendicular magnetic recording medium at least comprising a soft-magnetic layer 13, a seed layer 14, an intermediate layer 15, a magnetic recording layer 16 and a protection layer 17 which are stacked over a substrate 11 in order, the magnetic recording layer has a granular structure which includes many columnar grains of CoCrPt alloy and a grain boundary layer containing an oxide, the seed layer is made of TaNi alloy or TaTi alloy and the intermediate layer is made of Ru or Ru alloy which contains ≥80 at.% Ru. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a magnetic recording medium capable of recording a large amount of information and a manufacturing method thereof, and more particularly to a magnetic recording medium suitable for high-density magnetic recording.

  In recent years, there has been a strong demand for an increase in the capacity of a magnetic storage device, for example, a small-sized and large-capacity magnetic disk device is mounted not only in a personal computer but also in household electric products, and an improvement in recording density has been demanded. In order to cope with this, development of magnetic heads and magnetic recording media has been energetically performed. However, it has become difficult to improve the recording density using the in-plane magnetic recording method that is currently in practical use. Therefore, perpendicular magnetic recording has been studied as an alternative to in-plane magnetic recording. In the case of perpendicular magnetic recording, since the adjacent magnetizations do not face each other, the high-density recording state is stable, and it is considered that the system is essentially suitable for high-density recording. Also, by combining a single-pole type recording head and a double-layer perpendicular magnetic recording medium having a soft magnetic underlayer, it is possible to increase recording efficiency and cope with an increase in the coercive force of the recording film. . However, in order to realize high-density recording using the perpendicular magnetic recording method, it is necessary to develop a perpendicular magnetic recording medium that is low noise and resistant to thermal demagnetization.

  As a recording layer of a perpendicular magnetic recording medium, a CoCrPt-based alloy film that has been put to practical use in an in-plane magnetic recording medium has been conventionally studied. In order to obtain low noise characteristics using a CoCrPt-based alloy film, it is necessary to reduce exchange coupling between magnetic crystal grains by using Cr segregation to grain boundaries to reduce the magnetization reversal unit. However, when the amount of Cr is insufficient, the particles are coalesced and enlarged in the process of forming the recording layer, or the exchange coupling between the particles is insufficiently reduced, and low noise characteristics cannot be obtained. On the other hand, when the amount of Cr is increased, the magnetic anisotropy energy of the magnetic particles is lowered due to a large amount of Cr remaining in the particles, and sufficient resistance to thermal demagnetization cannot be obtained.

  In order to overcome such problems and obtain low noise characteristics, for example, as shown in Japanese Patent Application Laid-Open No. 2003-178413, a granular type recording layer in which an oxide is added to a CoCrPt alloy has been actively studied. It has come to be. When this granular type recording layer is used, the exchange coupling between the magnetic particles is reduced by forming an oxide grain boundary layer so as to surround the magnetic particles, so that the CoCrPt alloy is high regardless of the Cr concentration. A material having magnetic anisotropy energy can be used. In addition, since the grain boundary layer of the oxide is discontinuous in crystal with the magnetic particles and has a certain thickness, it is difficult for the particles to coalesce in the formation process of the recording layer. Therefore, a granular type perpendicular magnetic recording medium in which an oxide is added to a CoCrPt alloy has attracted attention as a candidate for a perpendicular magnetic recording medium that has low noise and is resistant to thermal demagnetization. The seed layer and the intermediate layer of the perpendicular magnetic recording medium have been extensively studied so far. For example, in Japanese Patent Application Laid-Open No. 2003-162807, B, C, Al, Si, P, Ti, Zr, Hf, Cr, V, Nb, Ta, Ru, Rd, Pd, Pt, Cu, Ag, Au and NiAl, NiTa in which these are combined with magnetic metals Fe, Co, Ni are disclosed, and an intermediate layer is disclosed. Co, Cr, Pt, Pd, Rh and Ru alloys are disclosed. Further, it has been reported, for example, in IEEE Transactions on Magnetics, Vol. 38, No. 5, p. 1976 (2002) that Ru is suitable as an intermediate layer of an oxide granular type perpendicular magnetic recording medium. Further, it has been reported in IEEE Transactions on Magnetics, Vol. 38, No. 5, p. 1979 (2002) that the Ta seed layer can improve the crystal orientation of the Ru intermediate layer.

JP 2003-178413 A Japanese Patent Laid-Open No. 2003-162807 IEEE Transactions on Magnetics, Vol.38, No.5, p.1976 (2002) IEEE Transactions on Magnetics, Vol.38, No.5, p.1979 (2002)

  So far, noise characteristics and thermal demagnetization characteristics have been studied for oxide granular type perpendicular magnetic recording media, but sufficient investigation has not been made on corrosion resistance. Therefore, when a corrosion resistance test was performed on an oxide granular type perpendicular magnetic recording medium using a Ta seed layer and a Ru intermediate layer, which can obtain a high medium S / N ratio, a number of corrosion points were observed and there was a problem with the corrosion resistance. all right. When a non-magnetic CoCr alloy well known as an intermediate layer of a conventional in-plane magnetic recording medium is used instead of Ru as an intermediate layer, the corrosion resistance is improved, but the medium S / N is greatly reduced. did. In other words, it has been found that there is a problem that a combination of a conventionally known intermediate layer material and seed layer material cannot achieve both high medium S / N and corrosion resistance.

  The object of the present invention is to provide a perpendicular magnetic recording medium having a granular recording layer in which an oxide is added to a CoCrPt alloy, and by selecting a combination of the material and structure of the intermediate layer and the seed layer, the medium S / N is high and the corrosion resistance is high. It is to realize an excellent medium.

  In order to achieve the above object, according to one aspect of the present invention, in a perpendicular magnetic recording medium in which at least a soft magnetic layer, a seed layer, an intermediate layer, a magnetic recording layer, and a protective layer are sequentially stacked on a substrate. The magnetic recording layer has a granular structure composed of a large number of columnar grains made of a CoCrPt alloy and a grain boundary layer containing an oxide, the seed layer is composed of TaNi alloy or TaTi alloy, and the intermediate layer is made of Ru or Ru at 80 at.%. It is comprised by the Ru alloy contained above. The granular type perpendicular magnetic recording medium of the present invention achieves high medium S / N and excellent corrosion resistance by combining a seed layer made of TaNi alloy or TaTi alloy and an intermediate layer made of Ru or Ru alloy. At this time, further excellent corrosion resistance can be realized by using Ru or Ru alloy having high crystal orientation in the intermediate layer in contact with the seed layer. This perpendicular magnetic recording medium is characterized in that the full width at half maximum of a rocking curve of Ru (0002) diffraction measured using an X-ray diffractometer is 4 degrees or less. The seed layer is preferably a TaNi alloy containing 20 to 80 at.% Ni or a TaTi alloy containing 10 to 40 at.% Ti.

  In order to improve the corrosion resistance of the perpendicular magnetic recording medium, it is considered effective to use a material having excellent corrosion resistance as a material used for each layer constituting the medium. However, it has been found that even when materials having equivalent corrosion resistance are used, a large difference occurs in the corrosion resistance as a medium. As a result of detailed examination, it was found that not only the corrosion resistance of each material itself but rather the combination of materials affects the corrosion resistance of the medium. The electrochemical properties and adhesion between materials are considered to be important factors that determine the corrosion resistance. Furthermore, regarding the adhesion between materials, not only the combination of materials but also crystallinity is considered as an important factor. The present invention is characterized in that excellent corrosion resistance is realized by a combination of TaNi alloy or TaTi alloy and Ru, and it has been found that it is important to control the crystal orientation of Ru.

  On the other hand, in order to obtain a high medium S / N, it is necessary to increase the surface unevenness of the intermediate layer on the recording layer side to promote the segregation of oxides on the crystal grain boundaries of the magnetic recording layer. That is, in order to achieve both high medium S / N and excellent corrosion resistance, it is necessary to use an intermediate layer having good crystal orientation and large surface irregularities. In order to realize such an intermediate layer, in the method for manufacturing a perpendicular magnetic recording medium according to the present invention, the intermediate layer is made of Ru or Ru alloy in which a lower intermediate layer and an upper intermediate layer different in manufacturing method are laminated, and an upper intermediate layer is formed. The gas pressure when forming the layer is made higher than the gas pressure when forming the lower intermediate layer. The gas pressure when forming the lower intermediate layer is desirably 0.3 Pa or more and 1 Pa or less. Instead of changing the gas pressure when forming the lower and upper intermediate layers, the same effect can be obtained by changing the film formation rate, in which case the lower intermediate layer is formed higher than the upper intermediate layer. Form at the rate. Further, both the gas pressure and the film forming rate may be changed when forming the lower intermediate layer and the upper intermediate layer.

  According to the present invention, in an oxide granular type perpendicular magnetic recording medium, by selecting a combination of an intermediate layer made of Ru or Ru alloy and a seed layer made of TaNi or TaTi alloy, the medium S / N is high and the corrosion resistance is high. An excellent medium can be realized.

A perpendicular magnetic recording medium was manufactured using an ANELVA sputtering apparatus (C3010). This sputtering apparatus is composed of 10 process chambers and one substrate introduction chamber, and each chamber is evacuated independently. The exhaust capacity of all the chambers is 6 × 10 ⁻⁶ Pa or less.

  The grain boundary width of the crystal grains was determined by observing a bright field image of the magnetic recording layer with a transmission electron microscope. In the bright field image of the granular medium, the crystal grain portion is observed as a dark contrast portion because the diffraction intensity is strong, and the grain boundary portion made of oxide is observed as a bright contrast portion because the diffraction intensity is weak. The width of each grain boundary was obtained by drawing a line connecting the gravity center positions of adjacent crystal grains and obtaining the length of the grain boundary part on the line. The grain boundary width was obtained for 100 or more grain boundaries, and these were arithmetically averaged to obtain the average grain boundary width.

  The recording / reproduction characteristics were evaluated by a spin stand. The head used for the evaluation is a composite magnetic head composed of a reproducing element using a giant magnetoresistance effect with a shield gap length of 55 nm and a track width of 120 nm, and a single-pole writing element with a track width of 170 nm. Reproduction output and noise were measured under conditions of a peripheral speed of 10 m / s, a skew angle of 0 degree, and a magnetic spacing of about 15 nm, and the medium S / N was a solitary wave reproduction output when a signal having a linear recording density of 1970 fr / mm was recorded. It was determined as the ratio of integrated noise when a signal having a linear recording density of 23620 fr / mm was recorded.

The corrosion resistance was evaluated according to the following procedure. First, the sample is allowed to stand for 96 hours under conditions of a high temperature and high humidity state at a temperature of 60 ° C. and a relative humidity of 90% RH or higher. Next, the number of corrosion points within a radius of 14 mm to 25 mm was counted using an Optical Surface Analyzer, and ranked as follows. A sample having a count number of less than 50 was evaluated as A, a sample having a count of 50 or more and less than 200 was evaluated as B, a sample having a count of 200 or more and less than 500 was evaluated as C, and a sample having 500 or more was evaluated as D. In practice, a rank of B or higher is desirable.
Embodiments of the present invention will be described below with reference to the drawings.

  As shown in FIG. 1A, in the perpendicular magnetic recording medium of this example, a precoat layer 12, a soft magnetic layer 13, a seed layer 14, an intermediate layer 15, a magnetic recording layer 16, and a protective layer 17 are sequentially formed on a substrate 11. It has a laminated structure. As the substrate 11, a glass substrate having a thickness of 0.635 mm and a diameter of 65 mm was used. First, a Ni-37.5 at.% Ta-10 at.% Zr precoat layer 12 was formed, and a Co-8 at.% Ta-5 at.% Zr having a total film thickness of 100 nm was formed thereon as a soft magnetic layer 13. The soft magnetic layer 13 has a structure in which two layers are antiferromagnetically coupled via Ru. After forming the soft magnetic layer 13, a seed layer 14 and an intermediate layer 15 are formed, and a film thickness 12 is obtained by adding 17.5vol.% Of Si oxide to a Co-17at.% Cr-14at.% Pt alloy thereon. A 4 nm magnetic recording layer 16 and a 4 nm thick CN protective layer 17 were formed. Ar was used as the sputtering gas, and oxygen was added at a partial pressure of 20 mPa when forming the magnetic recording layer. When forming the protective layer 17, nitrogen was added at a partial pressure of 50 mPa with respect to an Ar pressure of 0.6 Pa during film formation.

  In order to investigate the effect of the combination of the intermediate layer and the seed layer on the recording / reproducing characteristics and the corrosion resistance, various samples having different seed layer and intermediate layer materials were prepared. In all samples, the film thickness and film forming conditions of the seed layer and the intermediate layer were constant. The film thickness of the seed layer and the intermediate layer is 1 nm and 16 nm, respectively, the seed layer is formed with an Ar gas pressure of 0.6 Pa and a film formation rate of 1 nm / s, and the intermediate layer is formed with an Ar gas pressure of 2 Pa and a film formation rate of 0.3 nm / s. did. Table 1 shows the seed layer and intermediate layer materials, the medium S / N, and the corrosion resistance evaluation results of the prepared samples.

  First, focusing on the medium S / N, samples 1-9 to 16 using Ru or Ru alloy as the intermediate layer are much higher than samples 1-1 to 8 using Ti or CoCr alloy as the intermediate layer. S / N is obtained. The crystal grain boundary width of the magnetic recording layer of Sample 1-2 was determined to be 0.4 nm using a transmission electron microscope. On the other hand, the grain boundary width of Sample 1-14 from which the highest medium S / N was obtained was 1.1 nm, and the grain boundary width was significantly increased as compared with Sample 1-2. When the grain boundary widths of Samples 1-1 and 1-3 to 8 were also obtained, the grain boundary widths of Samples 1-1 to 8 having a low medium S / N were 0.5 nm or less. Thus, in a perpendicular magnetic recording medium having a granular type magnetic recording layer in which an oxide is added to a CoCrPt alloy, in order to obtain a high medium S / N, it is necessary to increase the width of the crystal grain boundary made of the oxide. Ru or Ru alloy is suitable as an intermediate layer for realizing this.

  Next, attention is focused on the results of the corrosion resistance evaluation. Samples 1-1 to 8 using Ti or CoCr alloy as the intermediate layer show relatively good corrosion resistance when there is no seed layer, but the corrosion resistance when Ta or Ta alloy is used as the seed layer is Not good. In any case, since the medium S / N is low as described above, it is a problem that the corrosion resistance and the high S / N cannot be achieved at the same time. On the other hand, with respect to Samples 1-9 to 16 using Ru or Ru alloy for which a high medium S / N is obtained as the intermediate layer, the variation in the corrosion resistance rank due to the seed layer is large. Samples 1-10 and 1-14 using Ta for the seed layer have a very low corrosion resistance of rank D, although a high medium S / N ratio is obtained. The Ta seed layer is very effective in improving the crystal orientation of the Ru intermediate layer and obtaining a high medium S / N, but it has been found that there is a problem in corrosion resistance when combined with the Ru intermediate layer. On the other hand, when the Ta-62.5 at.% Ni alloy or Ta-15 at.% Ti alloy with Ni or Ti added to Ta is used as the seed layer, Samples 1-11, 12 and 1-15, 16 It is. By combining the TaNi alloy or TaTi alloy seed layer and the Ru or Ru alloy intermediate layer, it is possible to obtain excellent corrosion resistance of rank B or higher while maintaining a high medium S / N as in the case of the Ta seed layer. It was. By adding Ni or Ti to Ta of the seed layer, the crystal matching at the interface with the Ru intermediate layer can be improved. As a result, the adhesion between the seed layer and the intermediate layer is improved, and the corrosion resistance is also improved. it is conceivable that.

  In Example 1, a magnetic recording layer in which 17.5 vol.% Of Si oxide was added to a Co-17 at.% Cr-14 at.% Pt alloy was used, but the addition amount of Si oxide was 15 vol. Co-15 at.% Cr-14 at.% Pt, Co-19 at.% Cr-14 at.% Pt, Co-17 at.% Cr-16 at.% Pt were used. In this case, the same tendency as in Example 1 was obtained. Further, as a result of examining various materials as oxides added to the magnetic recording layer, the same tendency as in Example 1 was observed in Al oxide, Ti oxide, Ta oxide, and B oxide in addition to Si oxide. It was. The effect of the present invention is remarkably exhibited when a material suitable for forming a crystal grain boundary having a width of about 1 nm is added to the magnetic recording layer so that an oxide is easily generated.

  Table 2 calculates the peel strength at the interface between the intermediate layer and the seed layer (referred to as interface 1 in Table 2) and the interface between the seed layer and the soft magnetic layer (referred to as interface 2 in Table 2) using molecular dynamics simulation. The results are shown. In the calculation, the seed layer material was changed by setting the intermediate layer to Ru and the soft magnetic layer to Co-8 at.% Ta-5 at.% Zr. The calculation was performed by the method disclosed in Journal of Materials Research Vol. 16, pp.1789-1794 (2001).

  When Ta-62.5 at.% Ni or Ta-25 at.% Ti was used as the seed layer, the peeling energy increased almost twice as compared with the case where the Ta seed layer was used at any interface. From this simulation result, it is considered that the use of the TaNi seed layer and the TaTi seed layer increases the peel strength at the interface with the soft magnetic layer and the Ru intermediate layer, thereby improving the corrosion resistance.

  The perpendicular magnetic recording media of Samples 2-1 to 4 were manufactured with the same film configuration and film forming conditions as Sample 1-15 of Example 1 except for the method of manufacturing the intermediate layer. Samples 2-1 and 2-2 have the configuration shown in FIG. 1-1, and samples 2-3 and 2-4 have the configuration shown in FIG. 1-2. 1-2 has the same configuration as that of FIG. 1-1 except for the intermediate layer 15, and has a configuration in which a lower intermediate layer 18 and an upper intermediate layer 19 are laminated instead of the intermediate layer 15. FIG.

  FIGS. 2-1 to 4 show production methods of Samples 2-1 to -4, respectively. In Samples 2-1 and 2-2, the intermediate layer was formed by one film forming process, whereas in Samples 2-3 and 2-4, the film forming process was changed between the lower intermediate layer and the upper intermediate layer. Samples 2-1 and 2-2 had an intermediate layer thickness of 16 nm. The thicknesses of the upper and lower intermediate layers of Samples 2-3 and 2-4 were 8 nm, respectively.

Table 3 shows the seed layer material of each sample, the drawing number of the manufacturing method, the grain boundary width of the magnetic recording layer obtained using a transmission electron microscope, and the Ru (0002) diffraction measured using an X-ray diffractometer. The half-value width Δθ ₅₀ of the rocking curve, the medium S / N, and the evaluation results of the corrosion resistance are shown.

First, paying attention to the results of the corrosion resistance, there was a difference in the evaluation results of the corrosion resistance in spite of using the same intermediate layer and seed layer materials. Samples 2-2 and 2-4, which have a small Δθ _{50 and} good crystal orientation of the Ru intermediate layer, have high corrosion resistance of A rank.

FIG. 3 shows the result of examining the relationship between the half-value width Δθ ₅₀ of the rocking curve of Ru (0002) diffraction and the corrosion resistance by preparing a sample with the same film configuration as that of Sample 2-1 and changing the film forming process of the intermediate layer. . When Δθ ₅₀ shows a high crystal orientation of 4 degrees or less, very excellent corrosion resistance of rank A or higher was obtained. In other words, it was found that not only the combination of film materials but also the crystal orientation is important for improving the corrosion resistance.

  Next, focusing on the medium S / N, in the samples 2-2 and 2-3 in which the intermediate layer and the upper intermediate layer in contact with the magnetic recording layer are formed in a low gas pressure atmosphere, the grain boundary width of the magnetic recording layer is narrow. Medium S / N is low. This is presumably because the intermediate layer formed in a low gas pressure atmosphere is less prone to irregularities on the surface, and therefore segregation of oxides to the crystal grain boundaries of the magnetic recording layer hardly occurs. From these results, in order to achieve both high medium S / N and excellent corrosion resistance, the intermediate layer in contact with the seed layer has high crystal orientation, and the intermediate layer in contact with the recording layer needs to have large surface irregularities.

  In order to realize the intermediate layer having such characteristics, as shown in Sample 2-4, the intermediate layer is composed of a lower intermediate layer and an upper intermediate layer having different manufacturing methods, and the lower intermediate layer is in a low gas pressure atmosphere. It is necessary to be a film that is formed with a high crystal orientation. That is, it has been found that high medium S / N and excellent A-rank corrosion resistance can be achieved by using a combination of a Ta-62.5 at.% Ni seed layer and a Ru intermediate layer and the manufacturing method shown in FIG.

Sample 2-5 has the same film configuration as sample 2-4 except for the material of the seed layer, and was manufactured using the same manufacturing method as sample 2-4. Ta-15 at.% Ti was used as the seed layer. Similar to sample 2-4, combining a Ta-15at.% Ti seed layer and a Ru intermediate layer and using the manufacturing method shown in FIG. 2-4 provides both high medium S / N and excellent A rank corrosion resistance. I knew it was possible. Similar results were obtained when Ru-5 at.% Ti, Ru-10 at.% Co, or Ru-15 vol.% SiO ₂ was used as the intermediate layer instead of Ru.

A sample with the same film configuration as sample 2-4 and with the gas pressure changed when forming the lower intermediate layer was prepared, and the relationship between the gas pressure and the value of the half-value width Δθ ₅₀ of the rocking curve of Ru (0002) diffraction was investigated. The results are shown in FIG. When the gas pressure was 1 Pa or less, Δθ ₅₀ showed a value of 4 degrees or less. Since the excellent corrosion resistance is exhibited when Δθ ₅₀ is 4 degrees or less, and a gas pressure of 0.3 Pa or more is necessary to obtain a stable discharge, the lower intermediate layer is 0.3 Pa or more and 1 Pa or less. It is desirable to form with gas pressure. Further, in order to obtain a high medium S / N, the upper intermediate layer needs to be formed in a gas pressure atmosphere higher than that of the lower intermediate layer, and the gas pressure at the time of forming the upper intermediate layer should be more than twice that of the lower intermediate layer It is desirable.

Sample 2-6 has the same film configuration as sample 2-4, and is a sample that differs only in the manufacturing method. Sample 2-6 was produced using the production method shown in FIG. Instead of changing the gas pressure when forming the lower intermediate layer and the upper intermediate layer, the film forming rate was changed. When the film is formed at a low film formation rate, the same effect as that formed in a high gas pressure atmosphere can be obtained, and surface irregularities are easily formed and the crystal orientation is deteriorated. On the other hand, when the film is formed at a high film formation rate, the same effect as that formed in a low gas pressure atmosphere can be obtained, and the crystal orientation is improved although the surface unevenness is hardly formed. In Sample 2-6, the lower intermediate layer was formed at a high film formation rate, and the upper intermediate layer was formed at a low film formation rate. In sample 2-6, as in sample 2-4, both high medium S / N and excellent A-rank corrosion resistance could be achieved. Intermediate layer as Ru Instead Ru-5at.% Ti and Ru-10at.% Co in the case of using a Ru-15vol.% SiO _2, the same even when using a Ta-15at.% Ti as a seed layer Results were obtained.

Sample 2-7 has the same film configuration as sample 2-4, and is a sample that differs only in the manufacturing method. Sample 2-7 was produced using the production method shown in FIGS. In Sample 2-7, the upper intermediate layer was formed in a higher gas pressure atmosphere than the lower intermediate layer and at a lower film formation rate. In sample 2-7, medium S / N and A rank corrosion resistance equivalent to sample 2-4 were obtained. Similar results are obtained when Ru-5 at.% Ti, Ru-10 at.% Co, Ru-15 vol.% SiO ₂ is used as the intermediate layer, and Ta-15 at.% Ti is used as the seed layer. It was.

The perpendicular magnetic recording medium of Example 3 was manufactured with the same film configuration and film forming conditions as Sample 2-4 of Example 2 except for the material of the seed layer. In Example 3, the composition of the TaNi alloy in the seed layer was changed. FIG. 5A shows the relationship between the composition of the seed layer and the count number of corrosion points, and FIG. 5B shows the relationship between the composition of the seed layer and the medium S / N. When the TaNi alloy contains 20 at.% Or more of Ni, excellent corrosion resistance of rank A or higher was obtained, and when Ni contained 80 at.% Or less, a high medium S / N was obtained. Similar results were obtained when Ru-5 at.% Ti, Ru-10 at.% Co, or Ru-15 vol.% SiO ₂ was used as the intermediate layer instead of Ru.

  From the above results, in order to realize a high medium S / N and excellent corrosion resistance in combination with Ru or a Ru alloy intermediate layer, the seed layer TaNi alloy contains 20 at.% Or more and 80 at.% Or less of Ni. desirable.

The perpendicular magnetic recording medium of Example 4 was manufactured with the same film configuration and film forming conditions as Sample 2-4 of Example 2 except for the material of the seed layer. In Example 4, a TaTi alloy was used as a seed layer, and the composition was changed. FIG. 6A shows the relationship between the composition of the seed layer and the count number of corrosion points, and FIG. 6B shows the relationship between the composition of the seed layer and the medium S / N. When the TaTi alloy contains 10 at.% Or more of Ti, excellent corrosion resistance of rank A or higher was obtained, and when Ti contained 40 at.% Or less, a high medium S / N was obtained. Similar results were obtained when Ru-5 at.% Ti, Ru-10 at.% Co, or Ru-15 vol.% SiO ₂ was used as the intermediate layer instead of Ru.

  From the above results, in order to realize high medium S / N and excellent corrosion resistance in combination with the Ru or Ru alloy intermediate layer, the TaTi alloy of the seed layer contains 10 at.% Or more and 40 at.% Or less of Ti. desirable.

The perpendicular magnetic recording medium of Example 5 was manufactured with the same film configuration and film forming conditions as Sample 1-15 of Example 1 except for the material of the intermediate layer. That is, a Ta-62.5 at.% Ni alloy was used as the seed layer. However, in Example 5, a RuCo alloy was used as the intermediate layer, and its composition was changed. Table 4 shows the material of the intermediate layer of the produced sample, and the evaluation results of the medium S / N and the corrosion resistance. Samples 5-1 to 5-1 exhibit high medium S / N and corrosion resistance higher than B rank, but samples 5-4 and 5-5 in which the Co content in the intermediate layer exceeds 20 at.% Are medium S / N. The corrosion resistance decreased to C rank. Similar results were obtained when Ru—Ti and Ru—SiO ₂ were used as the intermediate layer and Ta-15 at.% Ti was used as the seed layer.

  From the above results, in order to achieve both high medium S / N and corrosion resistance in an oxide granular type perpendicular magnetic recording medium, the intermediate layer needs to be a Ru alloy mainly composed of Ru, and the content of Ru is 80 at. It is desirable that it be at least.

The perpendicular magnetic recording medium of Example 6 was manufactured with the same film configuration and film forming conditions as Sample 2-4 of Example 2 except for the composition of the soft magnetic layer and the composition and thickness of the seed layer. In Example 6, Co-5 at.% Nb-10 at.% Zr was used as the soft magnetic layer. Table 5 shows the composition of the seed layer of the prepared sample, the film thickness, and the evaluation results of the medium S / N and the corrosion resistance. Sample 6-1 without a seed layer (comparative example) has the worst corrosion resistance and low medium S / N compared to samples 6-2 to 14. On the other hand, when the samples 6-2 to 14 having the seed layer are compared, a medium having a seed layer thickness of 1 nm or more shows A-rank corrosion resistance, and a sample layer having a seed layer thickness of 1 nm to 5 nm is particularly high. S / N was obtained. Here, the reason why the medium S / N is deteriorated in a sample having a seed layer thicker than 5 nm is considered to be caused by a decrease in recording efficiency due to an increase in the thickness of the seed layer. Ru-5at instead of Ru as the intermediate layer.% Ti and Ru-10at.% Co, the case of using a _{Ru-15vol.% SiO 2,} Ta-55at.% Ni as a seed layer, a Ta-10at.% Ti Similar results were obtained when used.

  From the above results, in order to achieve both high medium S / N and excellent corrosion resistance in oxide granular type perpendicular magnetic recording media, the thickness of the seed layer made of TaNi alloy or TaTi alloy is 1 nm or more and 5 nm or less. Is desirable.

1 is a diagram showing the structure of a perpendicular magnetic recording medium according to the present invention. 1 is a diagram showing the structure of a perpendicular magnetic recording medium according to the present invention. The figure which shows the manufacturing method of a perpendicular magnetic recording medium. The figure which shows the manufacturing method of a perpendicular magnetic recording medium. The figure which shows the manufacturing method of a perpendicular magnetic recording medium. The figure which shows the manufacturing method of a perpendicular magnetic recording medium. The figure which shows the manufacturing method of a perpendicular magnetic recording medium. The figure which shows the manufacturing method of a perpendicular magnetic recording medium. The figure which shows the relationship between the half value width (DELTA) (theta) ₅₀ of the rocking curve of Ru (0002) diffraction, and the number of corrosion points. The figure which shows the relationship between the Ar gas pressure at the time of forming a lower intermediate | middle layer, and the value of half value width (DELTA) (theta) ₅₀ of the rocking curve of Ru (0002) diffraction. The figure which shows the relationship between Ni content in the TaNi seed layer of a perpendicular magnetic recording medium, the number of corrosion points, and medium S / N. The figure which shows the relationship of Ti content in the TaTi seed layer of a perpendicular magnetic recording medium, the number of corrosion points, and medium S / N.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Substrate, 12 ... Precoat layer, 13 ... Soft magnetic layer, 14 ... Seed layer, 15 ... Intermediate layer, 16 ... Magnetic recording layer, 17 ... Protective layer, 18 ... Lower intermediate layer, 19 ... Upper intermediate layer

Claims (13)

A perpendicular magnetic recording medium in which at least a soft magnetic layer, a seed layer, an intermediate layer, a magnetic recording layer, and a protective layer are sequentially laminated on a substrate,
The perpendicular magnetic recording medium according to claim 1, wherein the seed layer is made of TaNi alloy or TaTi alloy, and the intermediate layer is made of Ru or Ru alloy.   2. The perpendicular magnetic recording medium according to claim 1, wherein a half width of a rocking curve of Ru (0002) diffraction measured with an X-ray diffractometer is 4 degrees or less.   3. The perpendicular magnetic recording medium according to claim 2, wherein the seed layer is made of a TaNi alloy containing Ni at 20 at.% Or more and 80 at.% Or less.   3. The perpendicular magnetic recording medium according to claim 2, wherein the seed layer is made of a TaTi alloy containing Ti at 10 to 40 at.%.   3. The perpendicular magnetic recording medium according to claim 2, wherein the intermediate layer is made of Ru or a Ru alloy containing 80 at.% Or more of Ru.   3. The perpendicular magnetic recording medium according to claim 2, wherein the magnetic recording layer has a granular structure composed of a number of columnar grains made of a CoCrPt alloy and a grain boundary layer containing an oxide. Magnetic recording medium. A substrate,
A soft magnetic layer formed on the substrate;
A seed layer made of TaNi alloy or TaTi alloy formed on the soft magnetic layer;
A lower intermediate layer made of Ru or an alloy obtained by adding a metal to Ru formed on the seed layer by a first gas pressure;
An upper intermediate layer made of Ru or Ru alloy formed on the lower intermediate layer by a second gas pressure higher than the first gas pressure;
A perpendicular magnetic recording medium comprising: a magnetic recording layer having a granular structure formed of a large number of columnar particles made of a CoCrPt alloy and a grain boundary layer containing an oxide formed on the upper intermediate layer. A substrate,
A soft magnetic layer formed on the substrate;
A seed layer made of TaNi alloy or TaTi alloy formed on the soft magnetic layer;
A lower intermediate layer made of Ru or an alloy obtained by adding a metal to Ru formed on the seed layer at a first deposition rate;
An upper intermediate layer made of Ru or Ru alloy formed on the lower intermediate layer at a second film formation rate lower than the first film formation rate;
A perpendicular magnetic recording medium comprising: a magnetic recording layer having a granular structure formed of a large number of columnar particles made of a CoCrPt alloy and a grain boundary layer containing an oxide formed on the upper intermediate layer. Forming a soft magnetic layer on the substrate;
Forming a seed layer made of TaNi alloy or TaTi alloy on the soft magnetic layer;
Forming a lower intermediate layer made of Ru or an alloy obtained by adding a metal to Ru at the first gas pressure on the seed layer;
Forming an upper intermediate layer made of Ru or a Ru alloy on the lower intermediate layer at a second gas pressure higher than the first gas pressure;
Forming a magnetic recording layer having a granular structure composed of a large number of columnar grains made of a CoCrPt alloy and a grain boundary layer containing an oxide on the upper intermediate layer. Production method. Forming a soft magnetic layer on the substrate;
Forming a seed layer made of TaNi alloy or TaTi alloy on the soft magnetic layer;
Forming a lower intermediate layer made of Ru or an alloy obtained by adding a metal to Ru on the seed layer at a first deposition rate;
Forming an upper intermediate layer made of Ru or Ru alloy on the lower intermediate layer at a second film formation rate lower than the first film formation rate;
Forming a magnetic recording layer having a granular structure composed of a plurality of columnar grains made of a CoCrPt alloy and a grain boundary layer containing an oxide on the upper intermediate layer. Production method.   2. The perpendicular magnetic recording medium according to claim 1, wherein the seed layer has a thickness of 1 to 5 nm.   8. The perpendicular magnetic recording medium according to claim 7, wherein the seed layer has a thickness of 1 to 5 nm.   9. The perpendicular magnetic recording medium according to claim 8, wherein the seed layer has a thickness of 1 to 5 nm.

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