JP2010086586A - 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, with which a yield of the perpendicular magnetic recording medium is improved by efficiently removing deposition in a chamber used for a step of depositing a protective layer so as to reduce mixing of particles in layers on the substrate. <P>SOLUTION: The method for manufacturing the perpendicular magnetic recording medium 100 includes: a magnetic recording layer-depositing step of depositing a magnetic recording layer 122 with a granular structure having a nonmagnetic grain formed between crystalline particles grown in columnar shapes, on the substrate 110; a protective layer-depositing step of depositing a carbon-based protective layer 126 with a CVD method; and a cleaning step of removing the deposition deposited in the chamber used for depositing the carbon-based protective layer by using ozone. <P>COPYRIGHT: (C)2010,JPO&amp;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 200 GB has been required for a 2.5-inch diameter magnetic recording medium used for HDDs and the like. In order to meet such a demand, one square is required. It is required to realize an information recording density exceeding 400 GB per inch.

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

As a magnetic recording medium used in the perpendicular magnetic recording system, a CoCrPt—SiO ₂ perpendicular magnetic recording medium (for example, Non-Patent Document 1) has been proposed because it exhibits high thermal stability and good recording characteristics. This is because in the magnetic recording layer, nonmagnetic Cr and SiO ₂ segregate between magnetic grains in which Co hcp structure (hexagonal close-packed crystal lattice) crystals are continuously grown in a columnar shape to form grain boundaries. To form a granular structure. Thereby, the refinement of the magnetic particles and the improvement of the coercive force Hc are achieved together.

  With the increase in the information recording density as described above, both the linear recording density in the circumferential direction (BPI: Bit Per Inch) and the track recording density in the radial direction (TPI: Track Per Inch) are steadily increasing. . Further, a technique for improving the S / N ratio by narrowing the gap (magnetic spacing) between the magnetic layer of the magnetic disk and the recording / reproducing element of the magnetic head has been studied. In recent years, the flying height of a magnetic head desired is 10 nm or less.

  As one technique for reducing the magnetic spacing, the head element generates heat during the operation of the magnetic head element, and the magnetic head is thermally expanded by the heat to move in the ABS (The air bearing surface) direction. A DFH (Dynamic Flying Height) head that slightly protrudes has been proposed. As a result, the gap between the magnetic head and the magnetic disk can be adjusted, and the magnetic head can always fly stably and with a narrow magnetic spacing.

In the perpendicular magnetic recording disk, a protective layer is provided to protect the surface of the magnetic recording layer from being damaged when the magnetic head collides with the perpendicular magnetic recording disk. The protective layer forms a high hardness film with a carbon overcoat (COC), that is, a carbon film. Some protective layers include a mixture of a hard diamond-like bond of carbon and a soft graphite bond (for example, Patent Document 1). Also disclosed is a technique for producing a diamond-like bond protective layer by a CVD (Chemical Vapor Deposition) method (for example, Patent Document 2).
Japanese Patent Laid-Open No. 10-11734 JP 2006-114182 A T. Oikawa et.al., IEEE Trans. Magn, vol.38, 1976-1978 (2002)

  By the way, as described above, there are various methods for forming the protective layer, but at present, the CVD method is most often used. In the film forming process of the protective layer by the CVD method, a substrate on which a layer just below the protective layer is formed is introduced into the chamber, and after the inside of the chamber is evacuated, ethylene gas is fed into the chamber. Then, a voltage is applied to the electrode provided in the chamber to make ethylene gas into plasma. As a result, carbon ions are generated, and the carbon ions adhere (arrive) to the substrate, and a protective layer, which is a film made of carbon atoms, is formed on the substrate. A film formed using such a CVD method has a higher film hardness than that formed using a sputtering method, and thus protects the perpendicular magnetic recording medium more effectively against the impact from the magnetic head. be able to.

  However, carbon ions generated by converting the ethylene gas into plasma in the chamber adhere not only to the substrate but also to places other than the substrate such as a shield inside the chamber. If carbon ions attached to locations other than the substrate continue to accumulate, a carbon film (deposit) is formed, and when the film thickness reaches a predetermined thickness, the film stress increases and the deposit is applied to the location. It peels from (locations other than a base | substrate). As a result, the peeled deposits become particles and are mixed in the layer formed on the substrate, thereby reducing the yield of the perpendicular magnetic recording medium.

  Therefore, in order to prevent a decrease in yield, a cleaning process for removing deposits in the chamber has been conventionally performed. In such a cleaning process, oxygen (gas) is used. Oxygen gas is generated in the chamber by the oxygen gas, and deposits adhering to locations other than the base are oxidized and ashed. Have been removed.

  However, the process time of the above-described cleaning process is as short as 4 seconds or less. For this reason, in such a cleaning process, it is not possible to oxidize and ash all the deposits adhering to places other than the base, and therefore, the mixing of particles into the layer on the base is reduced, The yield of perpendicular magnetic recording media does not reach the desired standard.

  Therefore, in order to improve the removal efficiency of deposits in the chamber, for example, extension of the process time of the cleaning process has been considered. However, when the process time was extended, the time required for exhausting the gas in the chamber used in the cleaning process had to be shortened. As a result, the oxygen gas used in the cleaning process remains in the chamber, and when the substrate on which the protective layer is to be formed is introduced into the chamber, the oxygen gas directly below the protective layer formed on the substrate is placed. The layer to be oxidized was oxidized by oxygen, and the quality of the perpendicular magnetic recording medium was deteriorated.

  For this reason, the removal of deposits in the chamber by the above-described cleaning process has reached its limit, and the yield of perpendicular magnetic recording media has reached its peak. Therefore, in order to improve the yield of the perpendicular magnetic recording medium, establishment of a new method capable of improving the removal efficiency of deposits in the chamber has been an issue.

  In view of such problems, the present invention efficiently removes deposits inside the chamber used in the protective layer film forming step, thereby reducing particle contamination in the layer on the substrate, and a perpendicular magnetic recording medium. It is an object of the present invention to provide a method of manufacturing a perpendicular magnetic recording medium capable of improving the yield of the recording medium.

  As a result of extensive studies by the inventors in order to solve the above-described problems, the inventors have focused on the fact that the use of a gas having a higher oxidizing ability than oxygen gas is effective in improving the deposit removal efficiency inside the chamber. And by further research, it has been found that ozone is suitable as a gas having a high oxidation ability, and the present invention has been completed.

  That is, in order to solve the above problems, a typical configuration of the method for manufacturing a perpendicular magnetic recording medium according to the present invention is that a nonmagnetic grain boundary portion is formed between crystal grains grown in a columnar shape on a substrate. A magnetic recording layer forming step for forming a magnetic recording layer having a granular structure, a protective layer forming step for forming a carbon-based protective layer by a CVD method, and a chamber used for forming the carbon-based protective layer And a cleaning step of removing the deposited deposit using ozone.

  In the above configuration, in the cleaning process, deposits accumulated inside the chamber used for forming the protective layer are removed using ozone. Since ozone has a remarkably higher oxidizing ability than oxygen conventionally used, deposits inside the chamber can be efficiently oxidized and ashed even in a short cleaning process. Therefore, the yield of perpendicular magnetic recording media can be further improved because the deposits can be removed more efficiently than before and the contamination of particles into the layer on the substrate can be significantly reduced in the same process time as before. Is possible.

  In addition, since the deposit can be efficiently removed in a short process time in the above configuration, a sufficient time can be obtained for exhausting the gas in the chamber used in the cleaning process. Therefore, it is possible to prevent highly reactive ozone from remaining in the chamber, and to prevent oxidation of a layer (a layer directly below the protective layer) formed on a substrate to be introduced into the chamber later. The quality of the perpendicular magnetic recording medium is not deteriorated.

  A gas mixing step for reducing the concentration of ozone in the chamber by injecting an inert gas into the chamber and mixing ozone with the inert gas, and an exhaust step for exhausting the mixed gas from the chamber And may be further included.

  As described above, deposit removal efficiency can be significantly improved by using ozone instead of oxygen in the cleaning process. However, on the other hand, due to the high reactivity of ozone, the flow path (exhaust flow path) for exhausting the gas inside the chamber may be corroded and damaged by ozone.

  Therefore, after performing the cleaning process using ozone as in the above configuration, the inert gas is mixed into the ozone in the chamber by injecting the inert gas into the chamber in the gas mixing process. Reduce the concentration. As a result, the gas passing through the exhaust passage is not only ozone or a gas containing high-concentration ozone, but is a gas (mixed gas) in which the ozone concentration is low, that is, ozone is diluted with an inert gas. . Accordingly, it is possible to prevent the exhaust passage from being corroded by ozone due to the passage of the exhaust gas containing ozone in the chamber, and to prevent the exhaust passage from being deteriorated and damaged.

  The inert gas may be a rare gas element. The rare gas element is chemically very stable, that is, inert because the outermost shell is closed in the electron configuration of atoms. Therefore, a rare gas element can be preferably used as the inert gas.

  The inert gas is preferably Ar. Since Ar is a rare gas element, the above-described advantages can be obtained. In addition, since Ar is used as an atmospheric gas in sputtering for forming a layer other than the protective layer, the use of Ar as an inert gas makes it possible to use a material as compared with the case where other rare gas elements are used. The increase in the number can be suppressed and the increase in cost can be prevented.

  Note that the inert gas may be a gas (gas) that has low reactivity and is chemically inert, and in addition to the rare gas element, nitrogen or the like can also be suitably used.

  The mixing ratio of the above mixed gas is preferably 15: 5 to 5:10 in the range of ozone: inert gas. By setting the mixing ratio of ozone and inert gas in the mixed gas within such a range, the above-described advantages can be most effectively obtained.

  The exhaust passage for exhausting the mixed gas from the chamber is preferably made of Cr-Fe alloy stainless steel not containing Ni.

  When stainless steel containing Ni is used as the exhaust flow path, Ni and ozone react with each other to cause corrosion, which may cause deterioration and damage to the exhaust flow path members. Therefore, by using stainless steel of Cr—Fe alloy not containing Ni for the exhaust passage as in the above configuration, corrosion of the exhaust passage due to ozone can be prevented, and deterioration and damage due to this can be avoided. .

  In the exhaust process, a reducing gas may be added to the mixed gas. A reducing gas is a gas having a reducing ability. Therefore, according to this configuration, ozone having a high oxidizing ability and a reducing gas having a reducing ability that are contained in the mixed gas can be reacted in the exhaust process to reduce the oxidizing ability of ozone. Thereby, deterioration and damage of the member of the exhaust passage for exhausting the mixed gas due to corrosion of ozone can be reduced. In addition, although hydrogen (gas) can be illustrated as a reducing gas, it is not limited to this, What is necessary is just a gas (gas) which has a reducing capability.

  It is preferable to further include an auxiliary recording layer film forming step for forming an auxiliary recording layer magnetically substantially continuous in the in-plane direction of the main surface of the substrate between the magnetic recording layer film forming step and the protective layer film forming step. .

  According to the above configuration, the auxiliary recording layer is provided between the magnetic recording layer and the protective layer. Thereby, the reverse domain nucleation magnetic field Hn can be improved to reduce noise, and the saturation magnetization Ms can be improved to improve the writeability, that is, the overwrite characteristic.

  Further, as described above, according to the present invention, the deposits can be efficiently removed in a short process time, so that a sufficient time for exhausting the gas in the chamber after the cleaning process can be secured. Therefore, it is possible to extremely reduce the residual ozone in the chamber. Therefore, it is possible to prevent oxidation of the layer formed on the substrate to be introduced into the chamber later, that is, the auxiliary recording layer, and the quality of the perpendicular magnetic recording medium is not deteriorated.

  According to the present invention, by efficiently removing deposits inside the chamber used in the protective layer film forming step, mixing of particles into the layer on the substrate is reduced, and the yield of the perpendicular magnetic recording medium is improved. It is possible to provide a method of manufacturing a perpendicular magnetic recording medium that can be used.

  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.

(Embodiment)
In this embodiment, first, an embodiment of a method for manufacturing a perpendicular magnetic recording medium according to the present invention will be described, and then a cleaning process, a gas mixing process, and an exhaust process will be described in detail.

[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. The perpendicular magnetic recording medium 100 shown in FIG. 1 includes a disk substrate 110, an adhesion layer 112, a first soft magnetic layer 114a, a spacer layer 114b, a second soft magnetic layer 114c, a pre-underlayer 116, a first underlayer 118a, and a second layer. The underlayer 118b, the nonmagnetic granular layer 120, the first magnetic recording layer 122a, the second magnetic recording layer 122b, the auxiliary recording layer 124, the protective layer 126, and the lubricating layer 128 are included. The first soft magnetic layer 114a, the spacer layer 114b, and the second soft magnetic layer 114c together constitute the soft magnetic layer 114. The first base layer 118a and the second base layer 118b together constitute the base layer 118. The first magnetic recording layer 122a and the second magnetic recording layer 122b together constitute the magnetic recording layer 122.

  As the disk substrate 110, a glass disk obtained by forming amorphous (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. The glass disk is subjected to grinding, polishing, and chemical strengthening sequentially to obtain a smooth non-magnetic disk base 110 made of a chemically strengthened glass disk.

  On the disk substrate 110, a film is sequentially formed from the adhesion layer 112 to the auxiliary recording layer 124 by a DC magnetron sputtering method, and the protective layer 126 can be formed by a CVD method. Thereafter, the lubricating layer 128 can be formed by dip coating.

  Note that it is also preferable to use an in-line film forming method in terms of high productivity. FIG. 2 is a layout diagram for explaining the layout of chambers for depositing each layer in the in-line film deposition method used in the present embodiment.

  As shown in FIG. 2, the disk substrate 110 is first introduced into a chamber in which the adhesion layer 112 is formed as shown by the white arrow in the figure. Thereafter, as shown by black arrows in the figure, the layers are introduced clockwise into a chamber for depositing each layer. In the present embodiment, there are two CVD chambers 150 (CVD 150a and 150b) for forming the protective layer 126, and they are arranged adjacent to each other in parallel. The CVD chamber 150a and the CVD chamber 150b alternately perform the formation of the protective layer 126 and the cleaning of the CVD chamber 150. For example, when the protective layer 126 is formed in the CVD chamber 150a, the CVD chamber 150b is formed. Then we are cleaning.

The cleaning is to remove adhering carbon by ashing (dry etching) the inside of the CVD chamber 150 using ozone (O ₃ ) plasma as will be described later. As described above, by providing a plurality of CVD chambers 150 and alternately performing the deposition of the protective layer 126 and the cleaning of the CVD chamber, it is possible to reduce defects in the substrate due to the deposited film deposition material without stopping the line. .

  Hereinafter, the configuration of each layer will be described.

  The adhesion layer 112 is formed in contact with the disk substrate 110, and has a function of increasing the peel strength between the soft magnetic layer 114 formed on the disk substrate 110 and the disk substrate 110, and the crystal grains of each layer formed thereon are finely divided. It has a function to make it uniform and uniform.

  The soft magnetic layer 114 is a layer that temporarily forms a magnetic path during recording in order to pass magnetic flux in a direction perpendicular to the recording layer in the perpendicular magnetic recording method. The soft magnetic layer 114 is provided with AFC (Antiferro-magnetic exchange coupling) by interposing a nonmagnetic spacer layer 114b between the first soft magnetic layer 114a and the second soft magnetic layer 114c. Can be configured. As a result, the magnetization direction of the soft magnetic layer 114 can be aligned along the magnetic path (magnetic circuit) with high accuracy, and the vertical component of the magnetization direction is extremely reduced, so that noise generated from the soft magnetic layer 114 is reduced. Can do.

  The pre-underlayer 116 is a non-magnetic alloy layer, and has an effect of protecting the soft magnetic layer 114 and the easy axis of the hexagonal close-packed structure (hcp structure) included in the underlayer 118 formed thereon. It has a function of orienting the disk in the vertical direction.

  The underlayer 118 has an hcp structure, and has a function of growing a Co hcp crystal of the magnetic recording layer 122 as a granular structure. Note that when the underlying layer 118 is made of Ru as in the present embodiment, a two-layer structure made of Ru can be obtained by changing the gas pressure during sputtering. Specifically, when forming the first underlayer 118a on the lower layer side, the Ar gas pressure is set to a predetermined pressure (low pressure), and when forming the second underlayer 118b on the upper layer side, the first underlayer 118 is formed. The gas pressure of Ar is set higher than when forming 118a, that is, a high pressure. Thereby, the crystal orientation of the magnetic recording layer 122 can be improved by the first underlayer 118a, and the grain size of the magnetic particles of the magnetic recording layer 122 can be reduced by the second underlayer 118b.

  The nonmagnetic granular layer 120 is a nonmagnetic layer having a granular structure. A non-magnetic granular layer is formed on the hcp crystal structure of the underlayer 118, and a granular layer of the first magnetic recording layer 122a (or magnetic recording layer 122) is grown thereon, whereby the magnetic granular layer is initially formed. It has the effect of separating from the growth stage (rise). Thereby, isolation of the magnetic particles of the magnetic recording layer 122 can be promoted.

  The magnetic recording layer 122 has a columnar granular structure in which a nonmagnetic substance is segregated around a magnetic particle of a hard magnetic material selected from a Co-based alloy, an Fe-based alloy, and a Ni-based alloy to form a grain boundary. Yes. By providing the nonmagnetic granular layer 120, the magnetic grains can be continuously epitaxially grown from the granular structure. Although the magnetic recording layer 122 may be a single layer, in this embodiment, the magnetic recording layer 122 includes a first magnetic recording layer 122a and a second magnetic recording layer 122b having different compositions and film thicknesses. As a result, small crystal grains of the second magnetic recording layer 122b continue to grow from the crystal grains of the first magnetic recording layer 122a, and the second magnetic recording layer 122b, which is the main recording layer, can be miniaturized. Can be improved.

In this embodiment, CoCrPt—Cr ₂ O ₃ is used for the first magnetic recording layer 122a. Also, CoCrPt—SiO ₂ —TiO ₂ is used for the second magnetic recording layer 122b. As a result, Cr and oxides (Cr ₂ O ₃ or SiO ₂ , TiO ₂ ), which are nonmagnetic substances, segregate around magnetic grains (grains) made of CoCrPt to form grain boundaries, and the magnetic grains are columnar. A grown granular structure was formed. The materials used for the first magnetic recording layer 122a and the second magnetic recording layer 122b are merely examples, and the present invention is not limited thereto.

  Furthermore, in this embodiment, one type of nonmagnetic material (oxide) is used in the first magnetic recording layer 122a and two types of nonmagnetic substances (oxides) in the second magnetic recording layer 122b. However, the present invention is not limited to this. It is also possible to use a composite of two or more kinds of nonmagnetic substances in either or both of the first magnetic recording layer 122a and the second magnetic recording layer 122b.

  The auxiliary recording layer 124 is a magnetic layer that is substantially magnetically continuous in the in-plane direction of the main surface of the substrate. The auxiliary recording layer 124 needs to be adjacent or close to the magnetic recording layer 122 so as to have a magnetic interaction. As a material of the auxiliary recording layer 124, for example, CoCrPt, CoCrPtB, or a small amount of oxides can be contained in these. The purpose of the auxiliary recording layer 124 is to adjust the reverse magnetic domain nucleation magnetic field Hn and the coercive force Hc, thereby improving the heat resistance fluctuation characteristic, the OW characteristic, and the SNR. In order to achieve this object, it is desirable that the auxiliary recording layer 124 has high perpendicular magnetic anisotropy Ku and saturation magnetization Ms. In the present embodiment, the auxiliary recording layer 124 is provided above the magnetic recording layer 122, but may be provided below.

  Note that “magnetically continuous” means that magnetism is continuous. “Substantially continuous” means that the magnetism may be discontinuous not by a single magnet but by grain boundaries of crystal grains when observed in the entire auxiliary recording layer 124. The grain boundaries are not limited to crystal discontinuities, and Cr may be segregated, and further, a minute amount of oxide may be contained and segregated. However, even when a grain boundary containing an oxide is formed in the auxiliary recording layer 124, it is preferable that the area is smaller than the grain boundary of the magnetic recording layer 122 (the content of the oxide is small). The function and action of the auxiliary recording layer 124 are not necessarily clear, but Hn and Hc can be adjusted by having magnetic interaction (perform exchange coupling) with the granular magnetic grains of the magnetic recording layer 122, and heat resistance. It is thought that fluctuation characteristics and SNR are improved. In addition, since the crystal grains connected to the granular magnetic grains (crystal grains having a magnetic interaction) have a larger area than the cross section of the granular magnetic grains, the magnetization is easily reversed by receiving a large amount of magnetic flux from the magnetic head. It is thought to improve the characteristics.

  The protective layer 126 is a carbon-based protective layer, and can be formed by depositing carbon by a CVD method while maintaining a vacuum (protective layer forming step). The protective layer 126 is a layer for protecting the perpendicular magnetic recording medium 100 from the impact of the magnetic head. In general, carbon deposited by the CVD method has improved film hardness compared to that deposited by the sputtering method, so that the perpendicular magnetic recording medium 100 can be more effectively protected against the impact from the magnetic head.

  The lubricating layer 128 can be formed of PFPE (perfluoropolyether) by dip coating. PFPE has a long chain molecular structure and binds with high affinity to N atoms on the surface of the protective layer 126. Due to the action of the lubricating layer 128, even if the magnetic head comes into contact with the surface of the perpendicular magnetic recording medium 100, damage or loss of the protective layer 126 can be prevented.

  Through the above manufacturing process, the perpendicular magnetic recording medium 100 was obtained. Next, the cleaning process, the gas mixing process, and the exhaust process will be described in detail.

  As described above, in the present embodiment, the deposition from the adhesion layer 112 to the auxiliary recording layer 124 is sequentially performed on the disk substrate 110 by the DC magnetron sputtering method, and the protective layer 126 is formed by the CVD method in the protective layer deposition step. Was formed. The disk substrate on which the protective layer has been formed moves to the next chamber, and the lubricating layer 128 is formed by the dip coating method. In the chamber used for forming the protective layer, the cleaning process described below is performed. A gas mixing step and an exhaust step are performed.

[Cleaning process]
In the cleaning step, deposits deposited inside the chamber used for forming the protective layer 126 are removed using ozone. Specifically, ozone is used to form the protective layer 126, that is, ozone is introduced into the chamber after the protective layer 126 is formed, and the ozone is ionized. Then, deposits deposited and deposited on portions other than the substrate inside the chamber are oxidized and ashed by ozone ions, gasified, and then removed by a pump.

  By using ozone in the cleaning process in this manner, the ability to oxidize the deposit is remarkably increased, so that the deposit in the chamber can be efficiently oxidized and ashed in a short time. Therefore, even in the same process time as the conventional cleaning process using oxygen, it is possible to remove deposits more efficiently than before, and to significantly reduce the mixing of particles into the layer on the disk substrate 110. Become. Thereby, the yield of the perpendicular magnetic recording medium 100 can be further improved.

  In addition, since the deposits can be efficiently removed in a short process time, it is possible to sufficiently secure the time required for exhausting the gas in the chamber. As a result, ozone used for cleaning can be surely exhausted from the chamber, and residual highly reactive ozone in the chamber can be prevented, so that a film is formed on a substrate to be introduced into the chamber later. It is possible to prevent the oxidation of the layer (the layer immediately below the protective layer 126, in this embodiment, the auxiliary recording layer 124), and the quality of the perpendicular magnetic recording medium 100 is not deteriorated.

[Gas mixing process]
In the gas mixing step, an inert gas is injected into the chamber after the cleaning step, and ozone is used as a mixed gas mixed with the inert gas, thereby reducing the concentration of ozone in the chamber. Thereby, the gas passing through the exhaust passage in the exhaust process described later is not only ozone or a gas containing high-concentration ozone, but a gas having a low ozone concentration, that is, ozone diluted with an inert gas ( Mixed gas). Therefore, since exhaust gas containing high-concentration ozone does not pass through the exhaust passage, that is, mixed gas in which ozone is diluted passes, corrosion of the exhaust passage due to highly reactive ozone is prevented, and the exhaust passage It becomes possible to prevent deterioration and damage of the product.

  Note that the mixing ratio of the mixed gas, that is, the mixing ratio of ozone and the inert gas is preferably in the range of ozone: inert gas of 15: 5 to 5:10. Thereby, the above-described advantages can be most effectively obtained. For example, when the ratio of ozone in the mixed gas is too large, the dilution of ozone becomes insufficient, and the effect of preventing corrosion of the exhaust passage due to ozone is reduced. In addition, when the proportion of ozone is too small, the amount of mixed gas exhausted from the chamber increases, so that the time required for exhaustion increases.

  The inert gas may be a rare gas element. The rare gas element is chemically very stable because of its electron arrangement, that is, inert, and therefore does not react with ozone or corrode the exhaust passage. Therefore, a rare gas element is suitable as the inert gas.

  Furthermore, among the noble gas elements, Ar is most suitable as the inert gas. Since Ar is used as an atmospheric gas in sputtering for forming a layer other than the protective layer 126, the use of Ar can suppress an increase in cost compared to the case where other rare gas elements are used. it can.

[Exhaust process]
In the exhaust process, the mixed gas generated in the gas mixing process, that is, the gas diluted with ozone is exhausted from the chamber. Thereby, ozone used for cleaning can be surely exhausted from the inside of the chamber, and the remaining highly reactive ozone in the chamber can be prevented.

  In the exhaust process, a reducing gas may be added to the mixed gas. Thereby, in the exhaust process, ozone having a high oxidizing ability contained in the mixed gas and a reducing gas having a reducing ability can be reacted to reduce the oxidizing ability of ozone. Therefore, deterioration and damage due to ozone of the members of the exhaust passage can be further reduced. Here, the reducing gas is a gas having a reducing ability. Examples of the reducing gas include hydrogen (gas), but are not limited thereto.

  Furthermore, the exhaust passage for exhausting the mixed gas from the chamber may be made of Cr-Fe alloy stainless steel not containing Ni. When stainless steel containing Ni is used as the exhaust flow path, Ni and ozone react with each other to cause corrosion, which may cause deterioration and damage to the exhaust flow path members. Therefore, by using stainless steel of Cr—Fe alloy not containing Ni for the exhaust passage, corrosion of the exhaust passage due to ozone can be prevented, and deterioration and damage due to this can be avoided.

  As described above, in this embodiment, deposit removal efficiency can be remarkably improved by using ozone instead of oxygen in the cleaning process of the method for manufacturing a perpendicular magnetic recording medium.

  Since ozone is highly reactive in the cleaning process, the flow path for exhausting the gas inside the chamber (exhaust flow path) may be corroded and damaged by ozone. A gas mixing step was introduced after the step. As a result, corrosion of the exhaust passage due to ozone can be reduced, and deterioration and damage due to this can be avoided.

(Example)
On the disk substrate 110, a film was formed in order from the adhesion layer 112 to the auxiliary recording layer 124 in an Ar atmosphere by a DC magnetron sputtering method using a film forming apparatus that was evacuated. The adhesion layer 112 was made of CrTi. In the soft magnetic layer 114, the composition of the first soft magnetic layer 114a and the second soft magnetic layer 114c was CoFeTaZr, and the composition of the spacer layer 114b was Ru. The composition of the pre-underlayer 116 was a NiW alloy having an fcc structure. As the first underlayer 118a, a Ru film was formed in an Ar atmosphere at a predetermined pressure (low pressure: for example, 0.6 to 0.7 Pa). As the second underlayer 118b, a Ru film containing oxygen was formed in an Ar atmosphere at a pressure higher than a predetermined pressure (high pressure: for example, 4.5 to 7 Pa) using a target containing oxygen. The composition of the nonmagnetic granular layer 120 was nonmagnetic CoCr—SiO ₂ . The first magnetic recording layer 122a contained Cr ₂ O ₃ as an example of an oxide at the grain boundary part, and formed a hcp crystal structure of CoCrPt—Cr ₂ O ₃ . The second magnetic recording layer 122b contains SiO ₂ and TiO ₂ as examples of complex oxides (plural types of oxides) in the grain boundary portion, and forms an hcp crystal structure of CoCrPt—SiO ₂ —TiO ₂ ( Magnetic recording layer deposition step). The composition of the auxiliary recording layer 124 was CoCrPtB (auxiliary recording layer film forming step). The protective layer 126 was formed using C ₂ H ₄ and CN by the CVD method (protective layer forming step), and the lubricating layer 128 was formed using PFPE by the dip coating method.

  FIG. 3 is a diagram illustrating the relationship between the gas used in the cleaning process and the amount of particles. An example is a perpendicular magnetic recording medium 100 in which a protective layer 126 is formed in a chamber that has been cleaned using ozone, and a comparative example is that in which a protective layer 126 is formed in a chamber that has been cleaned using oxygen. A perpendicular magnetic recording medium with a film. The amount of particles in Examples and Comparative Examples was measured with SEM-EDX.

  As shown in FIG. 3, in the example, when the protective layer 126 was formed in a chamber where the process time of the cleaning process was 0.5 seconds, it was confirmed that 1 Pcs particles were mixed in the perpendicular magnetic recording medium 100. However, when the protective layer 126 was formed in a chamber having a process time of 1.0 second or longer, no mixing of particles was confirmed.

  Further, in the comparative example, when a protective layer is formed in a chamber in which the process time of the cleaning process is 0.5 seconds to 1.5 seconds, mixing of particles is confirmed, and the process time is 2.0 seconds or more. In the case where the protective layer was formed in the chamber, the mixing of particles was not confirmed.

  Furthermore, the deposit film in the chamber was set to 100 nm, and the time until complete peeling was measured. When ozone was used in the cleaning process as in the example, the deposit was peeled off in 28 seconds. When oxygen was used in the cleaning process as in the comparative example, the separation of the deposit was completed in 50 seconds.

  Therefore, it can be understood from the above results that deposits can be removed in a shorter time than when oxygen is used by using ozone as a process gas in the cleaning process. As a result, the deposits in the chamber can be efficiently removed in a short time, and the mixing of particles into the perpendicular magnetic recording medium 100 can be reduced, so that the yield can be improved.

  FIG. 4 is a diagram showing the relationship between the gas used in the cleaning process and the coercive force Hc. An example is a perpendicular magnetic recording medium 100 in which a protective layer 126 is formed in a chamber that has been cleaned using ozone, and Comparative Example 1 has a protective layer formed in a chamber that has been cleaned using oxygen. The perpendicular magnetic recording medium is a film, and Comparative Example 2 is a perpendicular magnetic recording medium in which a protective layer is formed in a chamber that is not subjected to a cleaning process.

  FIG. 5 is a diagram showing the relationship between the gas used in the cleaning process and the compositional damage of the exhaust passage member. In the example, when a member having a composition that does not contain Ni is used in the exhaust channel, and the cleaning process is performed using ozone as the process gas, Comparative Example 1 uses a member that contains Ni in the exhaust channel. When the cleaning process is performed using ozone as the process gas, Comparative Example 2 is a case where the cleaning process is performed using a member having a composition containing Ni in the exhaust passage and oxygen as the process gas.

  As shown in FIG. 5, when ozone is used as the process gas in the cleaning process, if a member containing Ni is used in the exhaust passage as in Comparative Example 1, the member is damaged. By using a member having a composition containing Ni in the exhaust passage as in the example, damage to the member can be prevented. When oxygen is used as a process gas as in the conventional case as in Comparative Example 2, even if a member having a composition containing Ni is used in the exhaust flow path, the member is not damaged.

  As described above, by using ozone in the cleaning process, deposits inside the chamber used in the film formation process of the protective layer 126 are efficiently removed, and mixing of particles into the layer on the disk substrate 110 is reduced. The yield of the perpendicular magnetic recording medium can be improved.

  In addition, even if highly reactive ozone is used by adjusting the ratio of the inert gas mixed with ozone to an appropriate range or by devising a member of the exhaust passage, the exhaust passage is damaged by the ozone. Can be avoided.

  As mentioned above, although the suitable Example 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 or the like.

It is a figure explaining the structure of the perpendicular magnetic recording medium concerning this embodiment. It is an arrangement drawing explaining arrangement of a chamber. It is a figure explaining the relationship between the gas used for a cleaning process, and the amount of particles. It is a figure which shows the relationship between the gas used for a cleaning process, and the coercive force Hc. It is a figure which shows the relationship between the gas used for a cleaning process, and the damage of the composition of the member of an exhaust flow path.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 ... Perpendicular magnetic recording medium, 110 ... Disk base | substrate, 112 ... Adhesion layer, 114 ... Soft magnetic layer, 114a ... 1st soft magnetic layer, 114b ... Spacer layer, 114c ... 2nd soft magnetic layer, 116 ... Pre-underlayer, 118 ... Underlayer, 118a ... First underlayer, 118b ... Second underlayer, 120 ... Non-magnetic granular layer, 122 ... Magnetic recording layer, 122a ... First magnetic recording layer, 122b ... Second magnetic recording layer, 124 ... Auxiliary recording layer, 126 ... protective layer, 128 ... lubricating layer, 150 ... CVD chamber

Claims (8)

On the substrate,
A magnetic recording layer forming step of forming a granular magnetic recording layer in which a nonmagnetic grain boundary portion is formed between crystal grains grown in a columnar shape;
A protective layer forming step of forming a carbon-based protective layer by a CVD method;
And a cleaning step of removing deposits deposited inside the chamber used for forming the carbon-based protective layer using ozone. A gas mixing step of reducing the concentration of ozone in the chamber by injecting an inert gas into the chamber and using the ozone as a mixed gas mixed with the inert gas;
The method of manufacturing a perpendicular magnetic recording medium according to claim 1, further comprising an exhausting step of exhausting the mixed gas from the chamber.   The method for manufacturing a perpendicular magnetic recording medium according to claim 2, wherein the inert gas is a rare gas element.   The method of manufacturing a perpendicular magnetic recording medium according to claim 2, wherein the inert gas is Ar.   3. The method of manufacturing a perpendicular magnetic recording medium according to claim 2, wherein the mixed gas has a mixing ratio of ozone: inert gas of 15: 5 to 5:10.   3. The method of manufacturing a perpendicular magnetic recording medium according to claim 2, wherein the exhaust passage for exhausting the mixed gas from the chamber is made of Cr-Fe alloy stainless steel not containing Ni.   3. The method of manufacturing a perpendicular magnetic recording medium according to claim 2, wherein a reducing gas is added to the mixed gas in the exhausting step. Between the magnetic recording layer film forming step and the protective layer film forming step,
2. The method of manufacturing a perpendicular magnetic recording medium according to claim 1, further comprising an auxiliary recording layer film forming step of forming an auxiliary recording layer magnetically substantially continuous in an in-plane direction of the main surface of the substrate.

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