JP2012014779A - Method for manufacturing magnetic recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnetic recording medium with which the shortening of processing time can be achieved without deteriorating the removal efficiency of a pattern mask.SOLUTION: In a method for manufacturing a magnetic recording medium according to one embodiment of the prevent invention, the temperature of a substrate 11 is increased to the temperature region of removal reaction of a resist pattern 13 during a step of ion injection for magnetically separating a magnetic layer 12. After ion injection, the temperature of the substrate is utilized, performing the ashing processing of the resist pattern 13. As a result, the time of processing for removing a resist pattern can be shortened without deteriorating the removal efficiency of a resist pattern.

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. For example, Patent Document 1 described 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.

JP 2008-135092 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. For example, in the pattern mask removal step, the substrate is preheated to a temperature at which the mask removal reaction is promoted, thereby promoting the removal reaction and improving the mask removal efficiency. However, an extra processing time is required to preheat the substrate to the reaction temperature before the mask removal step, and a preheating chamber is necessary, which 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 removal efficiency of the pattern mask.

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 substrate is heated to a temperature of 150 ° C. or higher and 200 ° C. or lower while the exposed region is demagnetized.
The resist pattern on the substrate heated to the temperature by the ion implantation is removed by ashing.

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 relationship between ion implantation time and a substrate temperature demonstrated in the ion implantation process of the said embodiment. It is a figure which shows the relationship between the ion implantation energy and substrate temperature demonstrated in the ion implantation process of the said embodiment. It is a figure which shows the relationship between the ion implantation energy and substrate temperature demonstrated in the ion implantation process 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.

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 substrate is heated to a temperature of 150 ° C. or higher and 200 ° C. or lower while the exposed region is demagnetized.
The resist pattern on the substrate heated to the temperature by the ion implantation is removed by ashing.

  In the method of manufacturing a magnetic recording medium, the substrate is heated to a resist pattern removal reaction temperature range in an ion implantation step for magnetic separation of a magnetic layer, and the resist pattern is obtained using the substrate temperature after ion implantation. The ashing process is performed. Thereby, the processing time for resist pattern removal can be shortened without impairing the removal efficiency of the resist pattern.

  For the purpose of ashing removal of the resist pattern, the substrate temperature is set to 150 ° C. or higher and 200 ° C. or lower. When the substrate temperature is lower than 150 ° C., the reaction is not accelerated and it is difficult to secure a desired ashing rate. On the other hand, when the substrate temperature exceeds 200 ° C., the magnetic layer is deteriorated and it becomes difficult to obtain desired magnetic characteristics.

The magnetic layer generates heat due to the Joule heat of the ion current, and the heat generation temperature can be adjusted by the energy of the implanted ions. When the substrate temperature is raised to the above temperature range, the ion implantation energy can be, for example, 3000 [Ws] or more and 5000 [Ws] or less. The implantation energy can be adjusted by the dose amount of ions. When the dose amount is 1 × 10E15 (1 × 10 ¹⁵ ) [atoms / cm ² ], the implantation energy is, for example, 180 [keV × E15 atoms / cm ² ] or more and 320 [keV × E15 atoms / cm ² ] or less.

In the step of ashing the resist pattern, plasma of an ashing gas excited by microwaves can be 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. Therefore, by raising the substrate temperature to the above temperature range before ashing, the resist pattern can be removed at a high ashing rate, and the processing time can be shortened.

The method for manufacturing the magnetic recording medium may further include a step of forming a carbon-based protective film on the substrate heated to the temperature by the ion implantation.
In other words, the carbon-based protective film can be formed using the heat of the substrate that has been heated by the ion implantation process. In this case, it is not necessary to separately provide a substrate preheating step before film formation, and the processing time required for film formation can be shortened.
Further, by setting the substrate temperature before the film formation process to 150 ° C. or more and 200 ° C. or less, it is possible to secure a high film formation rate while suppressing magnetic deterioration of the magnetic layer.

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

[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.

  In the present embodiment, the temperature of the substrate 11 is raised to the decomposition reaction temperature of the resist pattern 13 using the heat generated by the substrate 11 accompanying the ion implantation process, and after the ion implantation, the temperature of the resist pattern 13 is increased using the substrate temperature. The ashing efficiency is improved.

The amount of heat generated by the ion implantation can be adjusted by the implantation energy and the dose.
That is, the Joule heat J [Ws] due to the charge of the ion beam is expressed by the following equation, where the energy of the ion beam is E [V], the beam current is I [A], and the implantation time is T [s (seconds)]. The
J = E × I × T (1)
Also, the injection time (T) is expressed by the following equation, where the dose is dose [atoms / cm ² ], the electric charge is q (= 1.60217733 × 10 ⁻¹⁹ coulomb), and the injection area is S [cm ² ]. The
T = dose × q × S / I (2)
The following equation is derived from the equations (1) and (2).
J = E × dose × q × S (3)

  FIG. 4 shows the experimental results showing the relationship between the ion implantation time (s) and the substrate temperature, measured with different ion implantation energies into the magnetic layer 12. As shown in FIG. 4, the longer the implantation time and the larger the implantation energy, the larger the temperature increase rate of the substrate. The required time is shorter as the implantation energy is larger. That is, the substrate temperature can be controlled by the ion implantation time and the implantation energy.

  On the other hand, FIG. 5 shows the experimental results showing the relationship between the ion implantation energy J [Ws] and the substrate temperature. As shown in FIG. 5, the ion implantation energy and the substrate temperature are in a substantially proportional relationship, and the larger the implantation energy, the higher the substrate temperature. In this case, the implantation energy required to raise the temperature of the substrate to the above ashing temperature (150 ° C. or more and 200 ° C. or less) is 3000 [Ws] or more and 5000 [Ws] or less.

Figure 6 shows the dose ^{1 × 10 15 [atoms / cm} 2] implantation energy when fixed to ^{[keV × E15atoms / cm 2 (} keV × 10 15 atoms / cm 2)] and the relation between the substrate temperature It is one experimental result. Also in this example, the substrate temperature rises in proportion to the ion implantation energy. In this case, the implantation energy required to raise the temperature of the substrate to the above ashing temperature (150 ° C. or more and 200 ° C. or less) is 180 [keV × E15 atoms / cm ² ] or more and 320 [keV × E15 atoms / cm ² ] or less. It is.

Therefore, by setting the ion implantation energy in the ion implantation step to 3000 to 5000 [Ws] or 180 to 320 [keV × E15 atoms / cm ² ], the substrate temperature is set to the target ashing temperature (150 to 200 ° C.). The temperature can be raised. As a result, the ashing process can be performed promptly after the substrate is transferred to the ashing chamber 103, and the resist pattern 13 on the substrate 11 can be removed at a high ashing rate as shown in FIG.

  In the present embodiment, the resist pattern 13 is ashed using the residual heat of the substrate 11 after the ion implantation process. Accordingly, it is not necessary to preheat the substrate before the ashing process, and the ashing process can be performed promptly after the ion implantation process. Thereby, the processing time required for removing the resist pattern 13 can be shortened without impairing the removal efficiency of the resist pattern 13. In addition, since it is not necessary to provide a substrate preheating chamber between the ion implantation chamber 102 and the ashing chamber 103, the equipment cost can be reduced.

  The ion implantation energy in the ion implantation process is not limited to being constant, and it is only necessary to reach the ashing treatment temperature (150 ° C. to 200 ° C.) at the end of the ion implantation process. In other words, the dose amount injected into the magnetic layer 12 and the heat generation of the substrate 11 can be controlled by changing the implantation energy according to the treatment time or intermittently performing the implantation treatment.

  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, the protective film 14 is formed on the surface of the magnetic layer 12 by plasma CVD or the like. The type of the protective film 14 is not particularly limited, and a diamond-like carbon (DLC) film is used in this embodiment, but other than this, a sputtered carbon film, a nitrogenated carbon film, a silicon nitride (SiN) film, and the like are used. Applicable. The method for forming the protective film 14 is not particularly limited, and for example, a vapor deposition method, a sputtering method, an ion plating method, a plasma CVD method, or the like is used.

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. 7 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. 7, 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. 8 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. 8, 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. 9 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 using the residual heat of the substrate 11 after the ion implantation process. 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 the removal reaction temperature range of the resist pattern 13 in the ion implantation process for magnetic separation of the magnetic layer 12, and the resist pattern is utilized using the substrate temperature after the ion implantation. 13 ashing processes are performed. Thus, the time required for the ion implantation process and the resist pattern removal process can be shortened without impairing the removal efficiency of the resist pattern 13.

  Further, according to the present embodiment, not only the resist pattern is removed by ashing, but also the subsequent deposition process of the protective film 14 can be performed using the heat generated by the substrate 11 accompanying the ion implantation process. This makes it possible to shorten the processing time required for the film formation process of the protective film 14, so that the process time can be shortened from the ashing process to the film formation process of the protective film, and productivity can be improved. It becomes like this.

  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 embodiment, the high-density magnetic recording medium represented by the patterned medium has been described as an example of the magnetic recording medium. However, the present invention is not limited to this, and for example, a magnetoresistive effect element represented by a magnetic head or MRAM. The present invention is also applicable to the manufacture of

  In the above embodiment, the plasma of the ashing gas excited by the microwave is used for the ashing process of the resist pattern 13, but the ashing process using the plasma excited by RF (hereinafter referred to as “second ashing process”). ") May be performed thereafter. The second ashing process does not depend on the substrate temperature, and the ashing rate can be controlled by the RF power or the substrate bias power. That is, in the second ashing process, the resist is removed by sputtering action of ions generated by plasma. Thereby, generation | occurrence | production of a resist residue can be reduced and the smoothness of the magnetic layer surface can be improved.

  The second ashing process is accompanied by heat generation of the substrate due to ion sputtering. Therefore, the protective film can be formed by using the residual heat of the substrate after the ashing process. That is, the second ashing process may be used for adjusting the substrate temperature before forming the protective film, and the substrate temperature may be optimized during the film forming 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 (5)

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 substrate is heated to a temperature of 150 ° C. or higher and 200 ° C. or lower while demagnetizing the exposed region,
A method of manufacturing a magnetic recording medium, wherein the resist pattern on the substrate heated to the temperature by the ion implantation is removed by ashing. 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 using plasma of an ashing gas excited by microwaves. The method of manufacturing a magnetic recording medium according to claim 1, further comprising:
A method of manufacturing a magnetic recording medium, wherein after removing the resist pattern, a carbon-based protective film is formed on the substrate heated to the temperature by the ion implantation. A method of manufacturing a magnetic recording medium according to claim 1,
The method of manufacturing a magnetic recording medium, wherein the ion implantation energy is 3000 [Ws] or more and 5000 [Ws] or less. A method of manufacturing a magnetic recording medium according to claim 1,
The method of manufacturing a magnetic recording medium, wherein the ion implantation energy is 180 [keV × E15 atoms / cm ² ] or more and 320 [keV × E15 atoms / cm ² ] or less.

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