JP2012014780A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium which can reduce a processing time without deteriorating film quality of a protective film.SOLUTION: The method for manufacturing the magnetic recording medium includes a step of ashing a resist pattern 13 which is used in an ion injection step for magnetically separating a magnetic layer 12. In the ashing step, the temperature of a substrate 11 is increased to a temperature suitable for forming a protective film 14, and after the ashing step, the protective film 14 is formed by utilizing the substrate temperature. Accordingly, the method can reduce a processing time for forming the protective film 14 without deteriorating film quality and film formation efficiency of the protective film 14.

Description

  The present invention relates to a method for manufacturing a magnetic recording medium used for manufacturing a patterned medium, for example.

  In recent years, in patterned media such as discrete tracks (DTR) and bit pattern media (BPM), nonmagnetic separation patterns for separating the recording areas are formed adjacent to the recording areas which are magnetic areas. ing. For the separation pattern, a UV resist, a hard mask, spin-on-glass (SOG), or the like is used, and the pattern mask is formed on the magnetic layer. Then, the magnetic layer is etched through this pattern mask, or ion implantation is performed on the magnetic layer, thereby forming a magnetically degraded separation pattern in the magnetic layer.

  In a high-density magnetic recording medium represented by a patterned medium, a high degree of flatness is required on the surface facing the magnetic head. For this reason, after the formation of the separation pattern, the resist pattern is removed from the surface of the magnetic layer. Thereafter, a protective film is formed on the surface of the magnetic layer. For example, Patent Document 1 below describes a method for manufacturing a magnetic recording medium in which a nonmagnetic region is formed by ion implantation, and then a mask layer is removed by dry etching using a gas containing chlorine to form a protective layer. ing.

JP 2002-288813 A

  In recent years, improvement in productivity of the magnetic recording medium has been demanded, and reduction of processing time in each process has been studied. On the other hand, in the magnetic recording medium, it is required to form a protective film having a stable film quality. For example, when a diamond-like carbon film is formed by a plasma CVD method as a protective film covering the surface of the magnetic layer, it is necessary to heat the substrate to a predetermined film formation temperature in order to ensure a desired film quality. However, adding a process of preheating the substrate to the above temperature before the process of forming the protective film requires an extra process required for preheating. In addition, the need for a preheating chamber inevitably increases equipment costs.

  In view of the circumstances as described above, an object of the present invention is to provide a method for manufacturing a magnetic recording medium capable of reducing the processing time without impairing the film quality of the protective film.

In order to achieve the above object, a method of manufacturing a magnetic recording medium according to an aspect of the present invention includes a step of forming an organic material resist pattern having an opening on the surface of a magnetic layer on a substrate.
By implanting ions into the exposed region of the magnetic layer exposed from the opening, the exposed region is demagnetized.
While the resist pattern is removed by ashing, the substrate is heated to a temperature of 140 ° C. or higher and 200 ° C. or lower.
A diamond-like carbon film is formed as a protective film on the substrate heated to the above temperature by ashing the resist pattern by a plasma CVD method.

1 is a plan view schematically showing an apparatus for manufacturing a magnetic recording medium according to an embodiment of the present invention. It is sectional drawing of the element explaining the manufacturing method of the magnetic-recording medium based on the said embodiment. It is a figure which shows the relationship between a substrate temperature and an ashing rate demonstrated in the removal process of the resist pattern of the said embodiment. It is a figure which shows the Raman spectral analysis result of a DLC film demonstrated in the film-forming process of the protective film of the said embodiment. It is a figure which shows the relationship between the film-forming temperature and area ratio Id / Is demonstrated in the film-forming process of the protective film of the said embodiment. It is a figure which shows the relationship between the film-forming temperature and the film-forming rate demonstrated in the film-forming process of the protective film of the said embodiment. It is sectional drawing of the element explaining the manufacturing method of the magnetic-recording medium based on the 2nd Embodiment of this invention.

A method of manufacturing a magnetic recording medium according to an embodiment of the present invention includes a step of forming an organic material resist pattern having an opening on the surface of a magnetic layer on a substrate.
By implanting ions into the exposed region of the magnetic layer exposed from the opening, the exposed region is demagnetized.
While the resist pattern is removed by ashing, the substrate is heated to a temperature of 140 ° C. or higher and 200 ° C. or lower.
A diamond-like carbon film as a protective film is formed as a protective film on the substrate heated to the above temperature by ashing the resist pattern.

  In the method of manufacturing the magnetic recording medium, the temperature of the substrate is raised to a temperature suitable for the formation of the protective film during the resist pattern removal step, and after the removal of the resist pattern, the protective film is formed using the substrate temperature. Membrane treatment is performed. Thereby, the processing time for forming the protective film can be shortened without deteriorating the film quality of the protective film.

  The diamond-like carbon (DLC) film formed as a protective film for the magnetic layer preferably has high strength and appropriate ductility. For example, a DLC film in which carbon on the G band and carbon on the D band are distributed at an appropriate ratio has ideal strength and durability as a protective film. When such a DLC film is formed by a plasma CVD method, the substrate temperature during film formation is set to 140 ° C. or higher and 200 ° C. or lower. A DLC film formed at a substrate temperature of less than 140 ° C. has a too strong G band and lacks ductility. On the other hand, a DLC film formed at a substrate temperature exceeding 200 ° C. cannot obtain sufficient strength because the D band is too strong.

  For example, a heater built in a stage that supports the substrate can be used to raise the temperature of the substrate in the resist pattern removing step. In this case, plasma of an ashing gas excited by microwaves can be used for the resist pattern ashing step. Such an ashing method mainly decomposes and removes a resist pattern by a chemical reaction with radicals generated by plasma. The decomposition reaction of the resist pattern depends on the substrate temperature, and the reaction is accelerated as the substrate temperature increases. Therefore, by raising the substrate temperature to the above temperature range during ashing, the resist pattern can be removed at a high ashing rate, and the processing time can be shortened.

  On the other hand, in the resist pattern ashing step, plasma of ashing gas excited by radio frequency may be used. This step includes a process of applying bias power to the substrate. Such an ashing process removes the resist pattern and raises the substrate temperature at the same time by the sputtering effect of ions generated by plasma. Therefore, by controlling the bias power applied to the substrate, not only the ashing rate of the resist pattern but also the degree of temperature rise of the substrate can be controlled. Therefore, by raising the temperature of the substrate to a temperature range suitable for the formation of the protective film by the ashing process, it is possible to quickly move to the protective film forming process after the ashing process.

  Further, as an ashing process for a resist pattern, a process using ashing gas plasma excited by microwaves (first ashing process) and a process using ashing gas plasma excited by high frequency (second ashing process) Treatment). In this case, since the resist pattern that could not be removed by the first ashing process can be removed by the second ashing process, the generation of resist residues can be suppressed. In addition, by performing the second ashing process in the latter half of the ashing process, it is possible to quickly move to the protective film forming step after the temperature of the substrate is increased.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
[Magnetic recording medium manufacturing equipment]
FIG. 1 is a plan view schematically showing an apparatus for manufacturing a magnetic recording medium according to an embodiment of the present invention. The manufacturing apparatus 100 according to this embodiment includes a load chamber 101, an ion implantation chamber 102, an ashing chamber 103, a film formation chamber 104, an unload chamber 105, and gates installed between these chambers 101 to 105. And a valve G.

  As indicated by an arrow A, the manufacturing apparatus 100 includes an inline-type transport mechanism that transports a substrate from the load chamber 101 toward the unload chamber 105. The transport mechanism may be a vertical transport mechanism that transports the substrate in an upright state in the vertical direction, or a horizontal transport mechanism that transports the substrate in a horizontal state. Further, a vacuum pump is connected to each of the chambers 101 to 105, not shown, and each chamber can be evacuated independently.

  The load chamber 101 conveys a substrate having a magnetic layer having a resist pattern formed on the surface thereof to the ion implantation chamber 102. The ion implantation chamber 102 eliminates the magnetism of the magnetic layer region exposed from the opening of the resist pattern by implanting ions into the substrate through the resist pattern. In the ashing chamber 103, the resist pattern on the substrate is removed by ashing. In the film formation chamber 104, a protective film is formed on the surface of the magnetic layer from which the resist pattern has been removed. The unload chamber 105 carries the substrate on which the protective film is formed to the outside of the apparatus.

[Method of manufacturing magnetic recording medium]
Next, a method for manufacturing a magnetic recording medium according to an embodiment of the present invention will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the element in each step for explaining the method of manufacturing the magnetic recording medium according to the present embodiment. In this embodiment, a patterned medium in which a plurality of magnetic regions are separated from each other by a nonmagnetic region will be described as an example of a magnetic recording medium.

  The method for manufacturing a magnetic recording medium according to the present embodiment includes a magnetic layer forming step, a resist pattern forming step, an ion implantation step, a resist pattern removing step, and a protective film forming step.

FIG. 2A shows a magnetic layer forming process. In this step, the magnetic layer 12 is formed on the substrate 11. The substrate 11 is typically a glass substrate or a silicon substrate, but of course is not limited thereto. The magnetic layer 12 is made of various ferromagnetic metals such as Fe, Co, and Ni, alloys, artificial lattices, and amorphous metals. In this embodiment, a Co—Cr—Pt—SiO ₂ film is used. The method for forming the magnetic layer 12 is not particularly limited, and examples thereof include a sputtering method and a vapor deposition method.

  The magnetic layer 12 is not limited to a single layer structure, and may have a multilayer structure. Further, an underlayer for improving adhesion to the substrate 11 or a protective layer for protecting the surface of the magnetic layer may be formed.

  FIG. 2B shows a resist pattern forming process. In this step, a resist pattern 13 that functions as a mask for forming a nonmagnetic region in the magnetic layer 12 is formed on the surface of the magnetic layer 12 by an ion implantation process described later. A known photosensitive resin material is used for the resist. The resist pattern 13 is formed by forming a resist layer on the surface of the magnetic layer 12 and then exposing and developing the resist layer in a predetermined pattern shape. The resist layer may be a liquid resist applied to the surface of the magnetic layer 12 or a dry film resist bonded to the surface of the magnetic layer 12.

  The resist pattern 13 has an opening 13a, and divides the magnetic layer 12 into a region covered with the resist pattern 13 and an exposed region exposed through the opening 13a. The opening 13a determines the shape of the nonmagnetic region, and the shape and size of the opening 13a are appropriately set according to the type and specification of the magnetic recording medium. For example, the thickness and pattern width of the resist pattern 13 necessary for producing a high-density magnetic recording medium represented by patterned media are, for example, on the order of several tens to several hundreds of nanometers.

  The substrate on which the resist pattern 13 is formed is transferred to the ion implantation chamber 102 through the load chamber 101. FIG. 2C shows an ion implantation process. In this step, ions are irradiated to the magnetic layer 12 using the resist pattern 13 as a mask. The exposed region of the magnetic layer 12 exposed from the opening 13a of the resist pattern 13 is demagnetized by ion implantation. As a result, a ferromagnetic region 12a covered with the resist pattern 13 and a nonmagnetic region 12b corresponding to the opening 13a of the resist pattern 13 are formed in the magnetic layer 12 (FIG. 2D). .

  The ions implanted into the magnetic layer 12 are not particularly limited, and nitrogen ions are used in this embodiment. In addition to these, various ions such as oxygen, boron, carbon, fluorine, barium, argon, and helium can be used. The amount (dose amount) of ions implanted into the magnetic layer 12 is not particularly limited, and is appropriately set according to the type of ions, the type of material of the magnetic layer 12, and the like.

  After the ion implantation process, the substrate 11 is transferred to the ashing chamber 103. FIG. 2D shows a removal process of the resist pattern 13. In this step, the resist pattern 13 is removed from the magnetic layer 12. In the removal process of the resist pattern 13, an ashing process using plasma such as oxygen or hydrogen is mainly employed.

  In particular, in the ashing process of the resist pattern 13 in this embodiment, ashing gas plasma excited by microwaves is used. Such an ashing method mainly decomposes and removes a resist pattern by a chemical reaction with radicals generated by plasma. The decomposition reaction of the resist pattern depends on the substrate temperature, and the reaction is accelerated as the substrate temperature increases.

  An example of the relationship between the substrate temperature and the ashing rate in microwave excited plasma ashing is shown in FIG. In this example, as ashing conditions, the ashing gas was hydrogen (flow rate 2000 sccm), the processing pressure was 100 Pa, the microwave frequency was 2.45 GHz, and the microwave power was 2 kW. In FIG. 3, the vertical axis represents the ashing rate at each temperature normalized with the ashing rate being 1 when the substrate temperature is 200 ° C.

As shown in FIG. 3, the ashing rate strongly depends on the substrate temperature, and a desired ashing rate cannot be secured unless the substrate is heated to a high temperature region exceeding 100 ° C. On the other hand, the higher the substrate temperature, the better the ashing rate. However, when the temperature exceeds 200 ° C, the magnetic transformation point (Curie point) approaches the magnetic transformation point depending on the type of magnetic layer (for example, Co-Cr-Pt-SiO ₂ ). There is a possibility that the characteristics are greatly deteriorated. In the present embodiment, the substrate temperature during the ashing process is set to 150 ° C. or more and 200 ° C. or less from the viewpoint of suppressing the deterioration of the magnetic layer and promoting the ashing process.

  For raising the temperature of the substrate 11 in the ashing process, for example, a heating source incorporated in a stage that supports the substrate 11 can be used. A heater or a heating medium can be used as the heating source. Furthermore, a hot plate may be employed for the stage. As described above, by adjusting the temperature of the stage (or hot plate), the substrate 11 can be heated to a temperature of 150 ° C. or higher and 200 ° C. or lower.

  After the ashing process is completed, the substrate 11 is transferred to the film formation chamber 104. FIG. 2E shows a protective film formation step. In this step, a diamond-like carbon (DLC) film is formed as a protective film 14 on the surface of the magnetic layer 12 by a plasma CVD method.

In the present embodiment, the protective film 14 is formed by a plasma CVD method. The film forming conditions are, for example, as follows.
Antenna frequency: 13.56 MHz
Antenna power: 1kW
Substrate bias frequency: 200 kHz (DC pulse)
Bias power: -300V
Deposition gas: C ₂ H ₄ (flow rate 200 sccm)
Deposition pressure: 1Pa

Since the DLC film has a film formation temperature dependency in its film characteristics, it is necessary to adjust the substrate temperature during film formation to an appropriate temperature range in order to obtain desired film characteristics. FIG. 4 shows the results of Raman spectroscopic analysis performed on a plurality of DLC films having different film forming temperatures. The film forming temperatures were 130 ° C., 170 ° C. and 230 ° C. Any of the DLC film also shows a spectrum constituted by two broad peak called D (Disordered) band around G (Graphitic) band and the wave number 1350 cm ^-1 in the vicinity of wave number 1550 cm ^-1. The G band is related to the amount of carbon (graphite) in the sp2 hybrid orbital, and the D band is related to the amount of carbon in the sp3 hybrid orbital. A DLC film having a higher deposition temperature has a higher intensity ratio of the D band to the G band, which indicates a decrease in the hardness of the DLC film.

  The DLC film used as the protective film 14 of the magnetic layer 12 preferably has high strength and moderate ductility. The strength of the film is expressed by carbon on the G band, and the ductility of the film is expressed by carbon on the D band. Therefore, a DLC film in which carbon on the G band and carbon on the D band are distributed at an appropriate ratio has ideal strength and durability as the protective film 14. In the example of FIG. 4, the DLC film formed at 130 ° C. has too strong G band and lacks ductility, and the DLC film formed at 230 ° C. has too strong D band to obtain sufficient strength. The DLC film formed at 170 ° C. has an appropriate function as a protective film because the G band and the D band have an appropriate intensity ratio. In this embodiment, when the area ratio of the D band peak and the G band peak is Id / Ig, a DLC film having an Id / Ig size of 2.25 or more and 2.75 or less is formed as the protective film 14.

  FIG. 5 shows one experimental result showing the relationship between the deposition temperature of the DLC film and the area ratio Id / Ig. The film formation temperature corresponds to the substrate temperature during film formation. It can be seen that the area ratio Id / Ig increases as the deposition temperature increases. From the results of FIG. 5, when the film forming temperature is 140 ° C. or higher and 210 ° C. or lower, an area ratio Id / Ig of 2.25 or higher and 2.75 or lower can be obtained.

  On the other hand, FIG. 6 shows one experimental result showing the relationship between the deposition temperature of the DLC film and the deposition rate. The film formation temperature corresponds to the substrate temperature during film formation. The film formation rate tends to decrease as the film formation temperature increases. From the viewpoint of productivity, the film formation rate is preferably 1 nm / sec or more. Therefore, when the substrate temperature (film formation temperature) is 140 ° C. or higher and 200 ° C. or lower, a DLC film having high strength and excellent durability can be formed efficiently.

  According to the present embodiment, the protective film 14 can be formed by using the residual heat of the substrate 11 after the ashing process of the resist pattern 13. In this case, it is not necessary to preheat the substrate before the film formation, and the protective film 14 can be formed immediately after the ashing process of the resist pattern 13. Thereby, the processing time required for forming the protective film 14 can be shortened without impairing the film formation efficiency and film characteristics of the protective film 14.

  Further, by setting the substrate temperature before the film formation process to 140 ° C. or more and 200 ° C. or less, it is possible to secure a high film formation rate while suppressing the magnetic deterioration of the magnetic layer 12. Furthermore, since it is not necessary to provide a substrate preheating chamber between the ashing chamber 103 and the film formation chamber 104, the equipment cost can be reduced.

  The magnetic recording medium 10 is manufactured by sequentially performing the above steps.

  According to the present embodiment, the temperature of the substrate 11 is raised to a temperature range suitable for the formation of the protective film 14 during the ashing removal process of the resist pattern 13, and after the ashing process, the substrate temperature is used to form the protective film 14. A film forming process is performed. Thereby, the time required for the film formation process of the protective film 14 can be shortened without impairing the film quality and film formation efficiency of the protective film 14.

<Second Embodiment>
FIG. 7 is a schematic cross-sectional view of an element in each step for explaining a method of manufacturing a magnetic recording medium according to another embodiment of the present invention. In the figure, portions corresponding to those of the first embodiment described above are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 7A shows an ion implantation process. In this step, as in the first embodiment described above, the magnetic layer 12 is magnetically separated into a magnetic pattern corresponding to the resist pattern 13 by ion implantation.

  FIG. 7B shows a first ashing process. In the first ashing process, an ashing gas plasma excited by microwaves is formed, and the resist pattern 13 is decomposed and removed by a chemical reaction with radicals generated by the plasma. In this case, the ashing rate has a strong temperature dependency as shown in FIG. 3, but, similarly to the first embodiment, by adjusting the temperature of the stage that supports the substrate 11, the substrate 11 is heated to 150 ° C. The temperature is maintained at 200 ° C. or lower. In the present embodiment, the first ashing process is performed under the same conditions as the processing conditions described in the first embodiment.

  FIG. 7C shows a second ashing process. In the second ashing treatment step, plasma of an ashing gas excited by a high frequency electric field such as RF (Radio Frequency) is formed, and the resist pattern is removed by the sputtering action of ions generated by the plasma. By performing the second ashing process, it is possible to remove the resist pattern that could not be removed by the first ashing process, so that the generation of resist residue is suppressed and the smoothness of the surface of the magnetic layer 12 is achieved. Can be increased.

  The ashing rate of the resist pattern 13 in the second ashing process is independent of the substrate temperature. Typically, RF plasma is formed by high frequency power of 13.56 MHz (1 kW). By applying bias power to the substrate 11, the sputtering action of the resist pattern 13 by ions in the plasma is promoted. The bias power is applied by a high frequency power source or a pulse power source connected to a stage (not shown) that supports the substrate 11. For example, the frequency of the bias power is 13.56 MHz and the bias power is 20 W. Hydrogen (flow rate 2000 sccm) is used as the ashing gas, and the processing pressure is, for example, 10 Pa.

  On the other hand, the temperature of the substrate 11 rises due to the incidence of ions on the substrate 11. Accordingly, in the second ashing process, the resist pattern 13 is removed and the substrate temperature is raised simultaneously by the sputtering action of ions generated by the plasma. Therefore, by controlling the bias power applied to the substrate, not only the ashing rate of the resist pattern but also the degree of temperature rise of the substrate can be controlled. Therefore, by raising the temperature of the substrate to a temperature range suitable for the formation of the protective film by the ashing process, it is possible to quickly move to the protective film forming process after the ashing process. For example, the substrate can be heated to a temperature range of 140 ° C. or higher and 200 ° C. or lower under the ashing conditions described above.

  FIG. 7D shows a process for forming the protective film 14. In this step, a diamond-like carbon (DLC) film is formed as a protective film 14 on the surface of the magnetic layer 12 by a plasma CVD method. The film forming conditions for the protective film 14 are the same as those in the first embodiment.

  According to the present embodiment, the temperature of the substrate 11 is raised to a temperature range suitable for the formation of the protective film 14 during the ashing removal process of the resist pattern 13, and after the ashing process, the substrate temperature is used to form the protective film 14. A film forming process is performed. Thereby, the time required for the film formation process of the protective film 14 can be shortened without impairing the film quality and film formation efficiency of the protective film 14.

  In particular, according to the present embodiment, since two processes of the first ashing process and the second ashing process are used in combination in the ashing removal process of the resist pattern 13, the resist residue is suppressed and the flatness is excellent. In addition, a magnetic recording medium can be manufactured.

  The embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made based on the technical idea of the present invention.

  For example, in the above-described second embodiment, the ashing removal process of the resist pattern 13 is used in combination with the two processes of the first ashing process and the second ashing process. It is also possible to carry out only by the second ashing process.

DESCRIPTION OF SYMBOLS 10 ... Magnetic recording medium 11 ... Substrate 12 ... Magnetic layer 12a ... Ferromagnetic layer 12b ... Nonmagnetic layer 13 ... Resist pattern 14 ... Protective film

Claims (3)

On the surface of the magnetic layer on the substrate, an organic material resist pattern having an opening is formed,
By implanting ions into the exposed region of the magnetic layer exposed from the opening, the exposed region is demagnetized,
While removing the resist pattern by ashing, the substrate is heated to a temperature of 140 ° C. or higher and 200 ° C. or lower,
A method for manufacturing a magnetic recording medium, comprising forming a diamond-like carbon film as a protective film on a substrate heated to the temperature by ashing the resist pattern by a plasma CVD method. A method of manufacturing a magnetic recording medium according to claim 1,
The step of ashing the resist pattern is a method of manufacturing a magnetic recording medium, including a process of forming a plasma of an ashing gas excited by a high frequency and applying a bias power to the substrate. A method of manufacturing a magnetic recording medium according to claim 1 or 2,
The method of manufacturing a magnetic recording medium, wherein the step of ashing the resist pattern includes a process of heating a temperature of a stage supporting the substrate to the temperature.

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