JP2004273010A - Method for manufacturing magneto-optical recording medium and sputtering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magneto-optical recording medium capable of manufacturing the magneto-optical recording medium of high recording density using magnetic super high resolution technology with high mass productivity, and further provide a sputtering system. <P>SOLUTION: The method for manufacturing the magneto-optical recording medium having a first process of disposing a plurality of targets 7a and 7b composed of materials different from each other and a sheet of substrate 4 opposite to each other and a second process of forming a magneto-optical recording layer composed of a magnetic material on the substrate by rotating the substrate without moving the substrate and performing sputtering while independently applying voltages to the plurality of targets and the sputtering system 1 used for the same are provided. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a magneto-optical recording medium and a sputtering apparatus.
[0002]
[Prior art]
Conventionally, optical recording media in which a signal recording layer, a dielectric layer, and the like are laminated on a substrate and a signal recording layer is illuminated with light to read and write information signals, and the optical recording medium is widely used. are doing.
[0003]
Among these optical recording media, a magneto-optical disk uses a magneto-optical recording film made of a rare-earth transition metal amorphous alloy or the like as a signal recording layer, and applies an external magnetic field while irradiating the signal recording layer with a laser beam. Thus, information is recorded. Reproduction of the recorded information is performed by irradiating the signal recording layer with laser light and detecting the rotation of the deflection surface of the reflected light. In these optical recording media, recording densities have been actively increased in order to record as much information as possible.
[0004]
Hitherto, the density of an optical recording medium has been increased by reducing the diameter of a light spot focused on the medium. The light spot diameter is limited by the wavelength (λ) of the light source used and the numerical aperture (NA) of the objective lens, and is approximately proportional to λ / (2NA). Therefore, in order to achieve high density, it is necessary to shorten the wavelength of laser light and increase the NA of the objective lens.
[0005]
The wavelength has been shortened from 830 nm for the first generation optical disc to 650 nm for the current DVD, and the NA has been increased to about 0.45 for the first generation optical disc and 0.60 for the DVD. Is progressing. Further, recently, development for practical use of an optical disk system using a blue laser having a wavelength of 400 nm as a light source and an NA of 0.85 has been actively performed.
[0006]
On the other hand, a technique (magnetic super-resolution) for reducing the effective light spot diameter by utilizing the interaction between the magneto-optical recording films has also been proposed. Magnetic super-resolution is achieved by magnetically masking the high-temperature part and / or the low-temperature part in the light spot using the temperature dependence of exchange coupling or magnetostatic coupling between multilayered magneto-optical recording films. It is a technology for reproducing by reducing the effective light spot diameter, and has now been commercialized.
[0007]
Further, as a method for solving the problem that the signal amount is reduced due to a decrease in the effective light spot diameter, there is a magneto-optical reproducing method and a reproducing apparatus disclosed in Patent Document 1. In this magneto-optical reproducing method, the data is transferred from a third magneto-optical recording layer (recording layer) to a first magneto-optical recording layer (domain wall moving layer) of a magneto-optical recording medium via a second magneto-optical recording layer (intermediate layer). The magnetic domain is reproduced by expanding the magnetic domain by moving a magnetic domain wall in a laser spot using a temperature gradient of a laser beam irradiated at the time of reproduction. Thereby, a dramatic improvement in the reproduction resolution can be achieved.
[0008]
With the recent increase in density of magneto-optical recording media, the size of recording marks held in a recording layer is also decreasing. Since the anisotropic energy of a recording mark is proportional to the volume of the recording mark, miniaturization of the recording mark directly leads to a decrease in anisotropic energy. As a result, problems such as the inability to hold the minute recording marks and the deterioration of the repetitive recording characteristics have arisen.
[0009]
In order to prevent this decrease in anisotropic energy, the magneto-optical recording film is composed of a multilayered multilayer film having a periodicity of a rare earth element and a transition metal, and the anisotropic energy per unit volume of the magneto-optical recording film is increased. Accordingly, means for compensating for the decrease in the volume of the recording mark is used (see Patent Document 2). Patent Document 2 discloses an example in which the perpendicular magnetic anisotropy becomes maximum when the period of the laminated film thickness is 1 to 2 nm in a laminated multilayer film having a periodicity of a rare earth element and an iron group metal.
[0010]
Such a magneto-optical recording film is formed using a self-revolution type sputtering apparatus 40 as shown in FIG. A plurality of substrate holders (not shown) are provided on the substrate carrier 41 of the self-revolution type sputtering apparatus 40, and the disk substrate 42 is held by the substrate holder. The plurality of substrate holders are arranged in a substantially circular shape around the central axis (revolution axis 43) of the substrate carrier 41.
[0011]
The substrate carrier 41 rotates around the revolving shaft 43, whereby the disk substrate 42 revolves, for example, in the direction indicated by the arrow A. Each substrate holder is provided with a mechanism for rotating the disk substrate 42. The disk substrate 42 revolves around the revolving shaft 43 while revolving around the revolving shaft 44 in a direction indicated by an arrow B, for example. A plurality of circular targets 45a to 45d are provided so as to face the substrate carrier 41. Usually, the targets 45 a to 45 d are arranged in a circle around the revolving axis 43 of the substrate carrier 41. FIG. 11 shows an example in which four targets are provided, but the number of targets is not limited.
[0012]
When forming a laminated multilayer film, targets 45a to 45d having different compositions are used. For example, a Tb (terbium) target is used as the target 45a, and an Fe is used as the target 45b. _x Co _1-x (Iron-cobalt) target, Fe on target 45c _y Co _1-y Fe on target, target 45d _z Co _1-z Use a target. x, y and z are different from each other and smaller than 1.
[0013]
By independently applying a voltage to these targets 45a to 45d and sequentially changing the targets to which the voltages are applied, an ultrathin layer having a TbFeCo film as a whole and different in composition microscopically was laminated. In addition, a laminated multilayer film having high anisotropic energy can be formed. The type of the target and the composition of the formed magneto-optical recording film are not limited to the above examples.
[0014]
On the other hand, when it is not necessary to use a plurality of targets having different compositions when the layers constituting the magneto-optical recording medium are formed by sputtering, a stationary facing single-wafer sputtering apparatus 50 as shown in FIG. 12 is used. Is often done. In the stationary facing single-wafer sputtering apparatus 50, one disk substrate 52 and one circular target 53 are arranged in one vacuum chamber 51 so as to face each other. The disk substrate 52 is held by the substrate holder 54 and is rotated about the axis 56 by the substrate rotation mechanism 55 in, for example, the direction indicated by the arrow A, but the position of the axis 56 does not change. Film formation is performed while the positions of the disk substrate 52 and the circular target 53 are kept constant.
[0015]
In the case of forming a multilayer multilayer film, a plurality of vacuum chambers corresponding to the number of films constituting the multilayer multilayer film are continuously installed. Each vacuum chamber has the same configuration as that of FIG. 12, and different targets are arranged one by one in these vacuum chambers. A disk substrate is sequentially moved between a plurality of vacuum chambers to form a film. Normally, a gate valve is provided between the adjacent vacuum chambers. However, the apparatus configuration without the gate valve can shorten the transfer time of the disk substrate (see Patent Document 3).
[0016]
[Patent Document 1]
JP-A-6-290496
[Patent Document 2]
JP 2002-197741 A
[Patent Document 3]
See JP-A-5-156442
[Patent Document 4]
JP-A-8-264526
[Patent Document 5]
JP 2000-353343 A
[Patent Document 6]
JP 2001-143220 A
[Patent Document 7]
JP-A-10-18031
[Patent Document 8]
JP-A-11-335835
[0017]
[Problems to be solved by the invention]
In the formation of the magneto-optical recording film, compared with the case of using a stationary facing single-wafer sputtering apparatus as shown in FIG. (Tact time) becomes longer. This is because the mechanism for rotating and revolving the substrate in the self-revolution type sputtering apparatus is complicated, and the vacuum chamber for accommodating such a mechanism must be enlarged. When the vacuum chamber is large, the time required to evacuate the vacuum chamber increases, and the time required to transport the substrate carrier also increases.
[0018]
Conventionally, in addition to the sputtering apparatus described in Patent Document 3, various sputtering apparatuses and methods used for manufacturing a magneto-optical recording medium and the like have been proposed. For example, Patent Document 4 discloses a method of forming a ferroelectric film on a substrate by sputtering while arranging a plurality of targets on a circumference and orbiting the substrate along the circumference. In the method, the rotation of the substrate is not essential. Patent Literature 4 describes that the time required for a substrate to pass over a target and the electric field applied to the target are adjusted to control the thickness of a formed ferroelectric film. According to this, the tact time becomes longer due to the transfer of the substrate.
[0019]
Patent Document 5 discloses a method of manufacturing a magneto-optical recording medium in which sputtering is performed while a pulse voltage is superimposed on a DC voltage applied to a target. This method is intended to improve the film quality, and sputtering is performed with one substrate and one target facing each other, and a plurality of targets are not used.
[0020]
Patent Document 6 discloses a method of uniformly forming an insulating layer constituting a magnetic head on a substrate by sputtering. According to this method, the substrate is turned 180 ° in the plane or parallelly moved during the sputtering while revolving the substrate facing the target. This method is suitable when the underlying substrate has a convex portion, and is not suitable when it is necessary to increase the in-plane uniformity of the film thickness as in a magneto-optical recording medium.
[0021]
Patent Document 7 discloses a sputtering apparatus in which a shielding plate is provided between a target and a substrate to improve the uniformity of the film thickness. Patent Document 8 discloses a self-revolving sputtering apparatus in which a plurality of substrates are opposed to a plurality of targets. However, since these devices are of the revolving type, the tact time of film formation cannot be reduced.
[0022]
As described above, the magneto-optical recording film to be reproduced using the magnetic super-resolution technique is a laminated multilayer film having a periodicity of a rare earth element and a transition metal in order to increase the anisotropic energy. Is preferred. However, conventionally, such a multilayer multilayer film has been formed by a self-revolution type sputtering apparatus, and thus has a problem that the tact time of film formation is long.
[0023]
The present invention has been made in view of the above problems, and therefore, the present invention can produce a magneto-optical recording medium of high recording density using magnetic super-resolution techniques such as magnetic domain expansion and domain wall movement with good mass productivity. An object of the present invention is to provide a method for manufacturing a magneto-optical recording medium. Another object of the present invention is to provide a sputtering apparatus capable of forming a magneto-optical recording film having high anisotropic energy in a short time.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a magneto-optical recording medium according to the present invention includes fixing a plurality of targets such that a plurality of targets made of mutually different materials and one substrate face each other; A first step of fixing the center position of the substrate, and sputtering is performed by rotating the substrate while independently applying a voltage to the plurality of targets to form a magneto-optical recording layer made of a magnetic material on the substrate. And a second step.
[0025]
In the second step, the application of the voltage to the plurality of targets may be simultaneously performed continuously or alternately. Preferably, the plurality of targets contain at least one of a rare earth element and a transition metal. Preferably, the second step is a step of forming a magneto-optical recording layer of a high-density magneto-optical recording medium using magnetic super-resolution, magnetic domain enlarging technology, or domain wall motion technology.
[0026]
Thereby, the tact time for forming the magneto-optical recording layer of the high-density recording magneto-optical recording medium can be significantly reduced. According to the method for manufacturing a magneto-optical recording medium of the present invention, in forming the magneto-optical recording layer, the substrate is stationary and opposed to the target without rotating, and is rotated. Since the mechanism for rotating the substrate is small, the size of the vacuum chamber in which the substrate and the target are stored does not increase, and the vacuum chamber can be evacuated in a short time. Further, the time for revolving the substrate is not required. Therefore, the productivity of the magneto-optical recording medium is improved as compared with the case where sputtering is performed while the substrate revolves around itself.
[0027]
In order to achieve the above object, a sputtering apparatus of the present invention has a vacuum chamber, a target fixing means for fixing a plurality of targets in the vacuum chamber, and a plurality of the targets fixed to the target fixing means. As described above, a substrate holding means for holding one substrate in the vacuum chamber, fixing the center position of the substrate, and rotating the substrate, and a voltage applying means for independently applying a voltage to the plurality of targets. It is characterized by having.
[0028]
This makes it possible to form a magneto-optical recording film having high anisotropic energy in a short time. Therefore, for example, a magneto-optical recording medium for high-density recording including a laminated multilayer film having a periodicity of a rare earth element and a transition metal can be manufactured with high productivity.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. According to the method of manufacturing a magneto-optical recording medium according to the present invention, a magneto-optical recording film composed of a multilayer multilayer film is formed using a stationary facing single-wafer sputtering apparatus 1 as shown in FIG. The stationary facing single-wafer sputtering apparatus 1 of this embodiment has a disk substrate holder 3 in a vacuum chamber 2.
[0030]
The disk substrate 4 on which the magneto-optical recording film is formed is held by the substrate holder 3. As the disk substrate 4, for example, a resin such as amorphous polyolefin or polycarbonate molded into a disk shape by injection molding or the like is used. The substrate holder 3 is rotated by the substrate rotation mechanism 5 about the shaft 6 in a direction indicated by an arrow A, for example. As a result, the disk substrate 4 rotates around the axis 6.
[0031]
A plurality of small-diameter targets 7 a and 7 b are arranged in the vacuum chamber 2 so as to face the disk substrate 4. The targets 7a, 7b are arranged around the axis 6, and the materials of the targets 7a, 7b are different from each other. FIG. 1 shows an example in which two targets are arranged, but the number of targets is not limited. Three or more targets having different materials and compositions (element abundance ratios) may be arranged so as to be arranged in a circle around the axis 6.
[0032]
A voltage applying mechanism is attached to each of the two targets 7a and 7b, so that a voltage can be independently applied to the targets 7a and 7b. The stationary facing single-wafer sputtering apparatus of this embodiment is a DC (direct current) magnetron sputtering apparatus. According to the stationary facing single-wafer sputtering apparatus of the present embodiment, it is desirable that the target is disposed so as to be inclined with respect to the disk substrate.
[0033]
In the case of a stationary facing single-wafer sputtering apparatus in which one disk substrate and one target are opposed to each other (see FIG. 12), a target sufficiently larger than the disk substrate is arranged in parallel with the disk substrate, so that the magneto-optical recording film is formed. Is made uniform over the entire surface of the disk substrate.
[0034]
On the other hand, in the case of the stationary facing single-wafer sputtering apparatus 1 shown in FIG. 1, since a plurality of targets 7a and 7b are arranged, the area where the disk substrate 4 and one target face each other is small. FIG. 2 is a plan view when the disk substrate 4 and the targets 7a and 7b in FIG. 1 are viewed in a direction parallel to the axis 6. The solid line indicates the disk substrate 4, and the dotted line indicates the projection of the targets 7a and 7b. The overlapping portion between the disk substrate 4 and one target is outside the axis 6.
[0035]
In this case, if the targets 7a and 7b are arranged in parallel with the disk substrate 4, the variation in the thickness of the magneto-optical recording film to be formed in the radial direction of the disk tends to increase. Therefore, the target is inclined at an angle such that the thickness of the magneto-optical recording film to be formed is uniform over the entire surface of the disk substrate.
[0036]
FIG. 3 is an enlarged view of the disk substrate 4 and the targets 7a and 7b of FIG. FIG. 3A shows a portion where a large amount of elements sputtered from the target 7a are present, and FIG. 3B shows a portion where a large amount of elements sputtered from the target 7b are present. As shown in FIG. 3, elements that reach the disk substrate 4 by being sputtered from one target have a high density in a part of the disk substrate 4.
[0037]
Even if the diameter of the target is increased, the change in the area of the portion facing the disk substrate is small, and the area of the portion not facing the disk substrate increases because of the geometrical restrictions due to the arrangement of other targets. Therefore, according to the stationary facing single-wafer sputtering apparatus 1 of the present embodiment, a large-diameter target is used for the purpose of equalizing the thickness of the magneto-optical recording film or increasing the number of elements reaching the disk substrate. No need. Even when a small-diameter target is used, a magneto-optical recording film having a uniform thickness can be formed as in the case of using a large-diameter target. Further, since the diameter of the target can be reduced, the use efficiency of the target is increased, and the cost of the target can be reduced.
[0038]
To describe a specific example, in the stationary facing single-wafer sputtering apparatus 50 shown in FIG. 12, for example, a target having a diameter of 127 mm is used for a disk substrate having a diameter of 64 mm, and the diameter of the target is twice the diameter of the disk substrate. That is all. On the other hand, in the stationary facing single-wafer sputtering apparatus 1 of this embodiment shown in FIG. 1, a target having a diameter of about 100 mm or less can be selected for the disk substrate 4 having a diameter of 64 mm.
[0039]
When the number of targets is increased, the diameter of the targets is further reduced so that the targets do not overlap. When three targets are used for a disk substrate having a diameter of 64 mm, for example, a target having a diameter of about 80 mm can be selected. As described above, the diameter of the target used in the stationary facing single-wafer sputtering apparatus 1 of the present embodiment has a uniform thickness in the stationary facing single-wafer sputtering apparatus in which one target faces one disk substrate. Is clearly smaller than the diameter of the target required to form the magneto-optical recording film. Note that the diameter of the target is not limited to the above example, and can be appropriately changed according to the number of targets, the geometrical arrangement of the targets including the angle at which the targets are inclined, and the like.
[0040]
Next, a method of forming a magneto-optical recording film having a high anisotropic energy using the stationary facing single-wafer sputtering apparatus 1 of the present embodiment will be described. In order to form a laminated multilayer film having a periodicity of a rare earth element and a transition metal, a rare earth element target made of, for example, Tb, Gd (gadolinium) or Dy (dysprosium) is used as one target 7a, and the other target 7b is made, for example. A transition metal target made of FeCo is used.
[0041]
Alternatively, two types of targets including the same rare earth element and transition metal as the targets 7a and 7b and having different ratios of the rare earth element and the transition metal may be used. For example, the target 7a has a higher rare earth element ratio Tb than the target 7b. ₃₅ (FeCo) ₆₅ And the target 7b has a higher transition metal ratio Tb than the target 7a. ₅ (FeCo) ₉₅ Can be used to form a laminated multilayer film having a periodicity of a rare earth element and a transition metal.
[0042]
As shown in FIG. 1, the disk substrate 4 is transported into the vacuum chamber 2 and fixed to the substrate holder 3, and then the vacuum chamber 2 is evacuated to a high degree of vacuum by a vacuuming mechanism (not shown). As the evacuation mechanism, for example, a cryopump, a turbo molecular pump, or the like is used. Thereafter, a rare gas such as Ar (argon), Kr (krypton), or Xe (xenon) is introduced into the vacuum chamber 2, and the target 7 a is rotated by the voltage application mechanism while rotating the disk substrate 4 using the substrate rotation mechanism 5. , 7b to discharge the target.
[0043]
The application of the voltage to the targets 7a and 7b may be performed continuously, alternately, or alternately. When a voltage is continuously applied to both of the targets 7a and 7b, the material of the target 7a is deposited and the element sputtered from the target 7b is deposited in a portion A where a large amount of elements sputtered from the target 7a are present as shown in FIG. In the portion B where a large amount of the target 7b exists, the material of the target 7b is deposited.
[0044]
In the portion where one of the target materials is deposited, the other target material is deposited as the disk substrate 4 rotates. By rotating the disk substrate 4 until a magneto-optical recording film having a predetermined thickness is formed, a laminated multilayer film having a periodicity of a rare earth element and a transition metal is formed. The period at which the rare earth element and the transition metal are stacked can be, for example, about 1 to 2 nm. It is known that by alternately laminating rare earth elements and transition metals at such a period, the anisotropic energy of the laminated multilayer film can be increased (see Patent Document 2).
[0045]
When a voltage is alternately applied to the targets 7a and 7b, the element is sputtered only from the target to which the voltage is applied. Therefore, for example, while the voltage is being applied to the target 7a, the material of the target 7a is deposited in the portion A shown in FIG. In this case, it is desirable that the discharge time T7a per one time of the target 7a and the discharge time T7b per one time of the target 7b be an integral multiple of the rotation period Tsub of the disk substrate 4. Thereby, the thickness of the layer formed of the material of the target 7a and the thickness of the layer formed of the material of the target 7b become constant. Therefore, the thicknesses of the rare earth element layer and the transition metal layer can be more strictly controlled.
[0046]
FIG. 4 is an example of a discharge time chart of the targets 7a and 7b. As shown in FIG. 4, a voltage is alternately applied to the targets 7a and 7b. The discharge time T7a and the discharge time T7b may be different. Further, the discharge time T7a and the discharge time T7b may partially overlap, and there may be a time during which two targets are simultaneously discharged.
[0047]
According to the stationary facing single-wafer sputtering apparatus 1 of the present embodiment shown in FIG. 1, the film forming time for forming a periodic multilayered film of a rare earth element and a transition metal is set as shown in FIG. For example, when the self-revolving type sputtering apparatus is used, it can be greatly reduced to about 1/10 to 1/20. For example, when a TbFeCo film is formed with a thickness of 50 nm, the apparatus according to the present embodiment can form a film in about 5 seconds, while a self-revolving apparatus requires about 50 to 100 seconds.
[0048]
If 10 to 20 disk substrates are mounted on one substrate carrier 41 (see FIG. 11) by a revolving type apparatus, the film forming time per disk substrate is calculated, and the sputtering apparatus 1 according to the present embodiment is used. Is equal to However, when the number of disk substrates to be mounted on the substrate carrier 41 is increased, the size of the vacuum chamber is increased, so that the time required to evacuate the vacuum chamber becomes longer or the size of the target needs to be increased. Therefore, it is not realistic to increase the number of disk substrates to be mounted on the self-revolution type device.
[0049]
Further, the substrate transfer time and the vacuum evacuation time are significantly shorter in the stationary facing single-wafer sputtering apparatus than in the self-revolving apparatus. For example, the time required for loading or unloading the disk substrate into or out of the apparatus may be about 1 second in the case of the sputtering apparatus of the present embodiment, whereas it is 30 seconds in the case of a revolving type apparatus. It takes about a second. As described above, according to the sputtering apparatus of this embodiment, both the time for depositing the magneto-optical recording layer by sputtering and the time for transporting the substrate and evacuation before and after the time can be significantly reduced.
[0050]
The stationary facing type single-wafer sputtering apparatus 1 of the present embodiment shown in FIG. 1 can be arranged continuously with another vacuum chamber for forming a layer constituting a magneto-optical recording medium. FIG. 5 is an example of a top view of the plurality of vacuum chambers 2. As shown in FIG. 5, a plurality of vacuum chambers 2 are arranged on a circumference, and one vacuum chamber is used as a disk substrate loading / unloading section 8.
[0051]
The disk substrate 4 is attached to the substrate holder 3 at the disk substrate loading / unloading section 8. The substrate holder 3 is connected to the expansion and contraction unit 9, and the expansion and contraction unit 9 contracts while the disk substrate 4 moves from one vacuum tank 2 to the adjacent vacuum tank 2. The inside of each of the vacuum chambers 2 and the portion where the expansion and contraction portion 9 is housed (the portion surrounded by the plurality of vacuum chambers 2) can be uniformly evacuated by a common vacuuming mechanism.
[0052]
A target 7 is fixed to each vacuum chamber 2, and a voltage is applied to the target 7 by a voltage application mechanism 10. In each vacuum chamber 2, one of the layers constituting the magneto-optical recording medium is formed by sputtering. A plurality of targets 7a and 7b are fixed to at least one vacuum tank 2A of the plurality of vacuum tanks 2 to obtain a configuration shown in FIG.
[0053]
The plurality of expansion / contraction sections 9 are rotated in a direction indicated by an arrow R, for example, by a rotation mechanism provided at the center of the plurality of vacuum chambers 2. A laminated film is formed by sputtering before the disk substrate 4 is loaded from the disk substrate loading / unloading unit 8 and is unloaded from the disk substrate loading / unloading unit 8 after making a round of each vacuum chamber 2. According to the sputtering apparatus having the above-described configuration, the laminated film constituting the magneto-optical recording medium can be manufactured without being exposed to the air.
[0054]
The configuration shown in FIG. 5 shows an example in which the sputtering apparatus 1 shown in FIG. 1 is arranged continuously with another vacuum chamber, and the arrangement of the vacuum chamber is not limited to the example shown in FIG. For example, a plurality of vacuum chambers may be arranged in a row to separately provide a disk substrate carry-in section and a disk substrate carry-out section, and the disk substrate may be moved in one direction between the plurality of vacuum chambers to form a laminated film. .
[0055]
【Example】
(Example 1)
In order to confirm the effect of the present invention, the anisotropic energy per unit volume of the magneto-optical recording film manufactured by using the method for manufacturing a magneto-optical recording medium of the present invention was measured. FIG. 6 is a cross-sectional view showing a sample of the first embodiment. As shown in FIG. 6, a first dielectric layer 12, a magneto-optical recording layer 13 and a second dielectric layer 14 are laminated in this order on a Si (silicon) substrate 11, and the sample is measured for anisotropic energy. Was done.
[0056]
The first dielectric layer 12 and the second dielectric layer 14 were formed using a stationary facing single-wafer sputtering apparatus (see FIG. 12) in which one target faces the Si substrate 11. The magneto-optical recording layer 13 is formed using the stationary facing single-wafer sputtering apparatus 1 of the embodiment of the present invention as shown in FIG. 1 for the samples 1-1 and 1-2, and for the comparative sample 1-3. Was formed using a stationary facing single-wafer sputtering apparatus 50 in which one target as shown in FIG. 12 was opposed to a substrate.
[0057]
(Sample 1-1)
In sample 1-1, the magneto-optical recording layer was formed while continuously applying a voltage to the two targets. Hereinafter, a method for producing Sample 1-1 will be described. First, a Si substrate and a Si target are placed in a vacuum chamber of a stationary facing single-wafer sputtering apparatus so as to face each other. ^-5 It was evacuated to about Pa. In this vacuum chamber, N gas is added in addition to Ar gas at a gas pressure of about 0.2 to 0.8 Pa. ₂ A gas was introduced and reactive sputtering was performed using a Si target to form a 30 nm-thick SiN film as the first dielectric layer 12. At this time, the power applied to the Si target was 2 kW, and the film formation time was 5.3 seconds.
[0058]
Next, 5 × 10 5 is previously installed continuously in the vacuum chamber in which the first dielectric layer 12 is formed. ^-5 The Si substrate on which the first dielectric layer 12 was formed was housed in a vacuum chamber in which the Tb target and the FeCo target evacuated to Pa or less were placed. An Ar gas is introduced into the vacuum chamber at a gas pressure of about 0.1 to 0.8 Pa, and a Tb target and a FeCo target are simultaneously sputtered while rotating the substrate, and a 50 nm thick TbFeCo film is formed as the magneto-optical recording layer 13. Was formed. At this time, the power applied to the Tb target was 300 W, the power applied to the FeCo target was 1.5 W, and the film formation time was 8 seconds.
[0059]
By rotating the substrate, ultra-thin layers having a high Tb abundance ratio and ultra-thin layers having a high abundance ratio of FeCo are alternately stacked inside the TbFeCo film. Such a microscopic structure can be confirmed by a transmission electron microscope (TEM) or Auger spectroscopy. The thickness of the ultra-thin layer having a high Tb abundance ratio and the thickness of the ultra-thin layer having a high abundance ratio of FeCo are each about 0.5 nm, and two ultra-thin layers are stacked at a period of about 1 nm. The rotation speed and the voltage applied to the target were adjusted.
[0060]
Next, 5 × 10 5 is installed continuously in the vacuum chamber in which the magneto-optical recording layer 13 is formed. ^-5 The Si substrate 11 on which the first dielectric layer 12 and the magneto-optical recording layer 13 were formed was housed in a vacuum chamber in which a Si target evacuated to Pa or less was placed. In addition to Ar gas, N ₂ (Nitrogen) gas was introduced, and the gas pressure was set at about 0.2 to 0.8 Pa. Then, reactive sputtering was performed using a Si target to form a 30-nm-thick SiN film as the second dielectric layer 14. At this time, the power applied to the Si target was 2 kW, and the film formation time was 5.3 seconds.
[0061]
(Sample 1-2)
In Sample 1-2, the magneto-optical recording layer was formed while alternately applying a voltage to the two targets. A sample was produced under the same conditions as in Sample 1-1 except that the magneto-optical recording layer 13 was formed.
[0062]
In forming the magneto-optical recording layer 13, first, a Tb target and an FeCo target are placed in a vacuum chamber, and the inside of the vacuum chamber is 5 × 10 ^-5 It was evacuated to about Pa. The Si substrate 11 on which the first dielectric layer 12 was formed was accommodated in this vacuum chamber. An Ar gas is introduced into the vacuum chamber at a gas pressure of about 0.1 to 0.8 Pa, and sputtering of a Tb target and an FeCo target is alternately repeated while rotating the substrate, so that the magneto-optical recording layer 13 has a thickness of 50 nm. Was formed. At this time, the power applied to the Tb target was 300 W, the power applied to the FeCo target was 1.5 W, and the film formation time was 16 seconds.
[0063]
The rotation period Tsub of the substrate was set to 0.25 seconds, and the discharge time T7a for one time of the Tb target and the discharge time T7b for one time of the FeCo target were both set to 0.25 seconds. As a result, similarly to the sample 1-1, the ultra-thin layer having a high Tb abundance and the ultra-thin layer having a high abundance of FeCo are laminated inside the TbFeCo film, and the ultra-thin layer having a high abundance of Tb and the FeCo The thickness of each of the ultrathin layers having a high abundance ratio was about 0.5 nm, and the cycle of laminating the two ultrathin layers was about 1 nm.
[0064]
(Comparative sample 1-3)
In Comparative Sample 1-3, a sample was manufactured under the same conditions as Samples 1-1 and 1-2 except for the formation of the magneto-optical recording layer 13. In forming the magneto-optical recording layer 13, first, a TbFeCo alloy target is placed in a vacuum chamber, and the inside of the vacuum chamber is 5 × 10 ^-5 It was evacuated to about Pa. The Si substrate 11 on which the first dielectric layer 12 was formed was accommodated in the vacuum chamber so as to face the alloy target.
[0065]
An Ar gas was introduced into the vacuum chamber at a gas pressure of about 0.1 to 0.8 Pa, and a TbFeCo alloy target was sputtered to form a 50 nm thick TbFeCo film as the magneto-optical recording layer 13. At this time, the power applied to the TbFeCo alloy target was 1 kW, and the deposition time was 6 seconds. In Comparative Sample 1-3, no periodic structure was formed inside the TbFeCo film because an alloy target was used.
[0066]
The anisotropic energy of the sample manufactured as described above was measured. Comparative sample 1-3 has an anisotropic energy of 3 × 10 ⁵ erg / cc, whereas Sample 1-1 is 8 × 10 ⁵ erg / cc, sample 1-2 is 1 × 10 ⁶ erg / cc. That is, in the magneto-optical recording layer formed by the method of the present invention, an increase in anisotropic energy was observed.
[0067]
(Example 2)
In a second embodiment, an example will be described in which the present invention is applied to the manufacture of a magneto-optical recording medium that performs reproduction by a DWDD method (domain wall displacement detection) capable of realizing a high recording density (see Patent Document 1). In the DWDD method, the magnetic domain transferred from the recording layer to the domain wall moving layer of the magneto-optical recording medium via the intermediate layer is moved by a magnetic domain wall in a laser spot by using a temperature gradient of a laser beam irradiated at the time of reproduction. The magnetic domain is enlarged and reproduced.
[0068]
As shown in FIG. 7, in the magneto-optical recording medium of the second embodiment, a first dielectric layer 22, a reproducing layer 23, a domain wall displacement layer 24, a first intermediate layer 25, and a second intermediate layer 26 are formed on a disk substrate 21. And a recording holding layer 27, a recording auxiliary layer 28, a second dielectric layer 29, a thermal diffusion layer 30, and a protective film 31 are laminated in this order.
[0069]
As the disk substrate 21, for example, a resin material such as amorphous polyolefin or polycarbonate molded into a disk shape by injection molding or the like is used.
The first dielectric layer 22 improves the optical efficiency of the magneto-optical recording medium and suppresses the diffusion of moisture from the disk substrate 21 into the reproducing layer 23 and the domain wall displacement layer 24, thereby preventing the disk from corroding. To prevent As the first dielectric layer 22, for example, a SiN film is formed with a thickness of about 40 to 100 nm.
[0070]
The reproduction layer 23 moves the domain wall of the magnetic domain transferred from the recording holding layer 27 together with the domain wall movement layer 24, and improves the reproduction signal characteristics. As the reproducing layer 23, a layer of, for example, GdFeCo or GdFe is formed with a thickness of about 5 to 50 nm.
The domain wall motion layer 24 is a layer that moves the domain wall of the magnetic domain transferred from the recording holding layer 27 and exerts a magneto-optical effect. As the magnetic transfer layer 24, for example, a layer of GdFeCo, GdFe, GdFeAl, GdFeSi or the like is formed with a thickness of about 5 to 50 nm.
[0071]
The first intermediate layer 25 and the second intermediate layer 26 are layers that control the transfer of magnetic domains from the recording holding layer 27 to the domain wall motion layer 24. Is formed with a thickness of 5 to 40 nm.
[0072]
The record holding layer 27 is a layer on which information signals are recorded and held. For example, a layer of TbFeCo or the like is formed with a thickness of 20 to 100 nm.
The recording auxiliary layer 28 improves recording characteristics by improving recording magnetic field sensitivity characteristics when an information signal is recorded on the recording holding layer 27. As the recording auxiliary layer 28, a layer of, for example, GdFeCo is formed with a thickness of 20 to 100 nm.
[0073]
The second dielectric layer 29 is provided to control the diffusion of heat due to the light applied to the magneto-optical recording medium and to improve the recording / reproducing characteristics. As the second dielectric layer 29, for example, a SiN film is formed with a thickness of about 50 to 80 nm.
The thermal diffusion layer 30 is provided for controlling the diffusion of heat due to the light applied to the magneto-optical recording medium and improving the recording / reproducing characteristics. As the thermal diffusion layer 30, for example, an Al layer is formed with a thickness of about 3 to 20 nm.
[0074]
The protective film 31 is for improving the resistance to damage and abrasion of the magneto-optical recording medium in the event of collision or contact with the recording magnetic head. For example, a UV curable resin is applied by a method such as spin coating. By doing so, it is formed with a thickness of about 5 to 20 μm.
[0075]
Of the above layers, all of the layers formed by sputtering are formed by a stationary facing single-wafer sputtering apparatus. Vacuum chambers for forming each layer are continuously installed in the order in which the layers are formed. Except for the vacuum chamber where the record holding layer 27 is formed, one target is arranged in the vacuum chamber. The record holding layer 27 is formed by applying the present invention, and two targets are arranged in a vacuum chamber for forming the record holding layer 27 as shown in FIG. According to such an apparatus configuration, a multilayer laminated film can be formed without exposing the magneto-optical recording medium to the atmosphere.
[0076]
The first dielectric layer 22, the reproducing layer 23, the domain wall displacement layer 24, the first intermediate layer 25, the second intermediate layer 26, the recording auxiliary layer 28, the second dielectric layer 29, and the heat diffusion layer 30 are as described above. Film formation was performed under normal sputtering conditions for forming layers of various materials and thicknesses. The record holding layer 27 was formed as follows.
[0077]
(Sample 2-1)
In forming the record holding layer 27, first, a Tb target and an FeCo target are set in a vacuum chamber, and the inside of the vacuum chamber is 5 × 10 ^-5 It was evacuated to about Pa. The disk substrate 21 on which the first dielectric layer 22, the reproducing layer 23, the domain wall motion layer 24, the first intermediate layer 25, and the second intermediate layer 26 were formed was accommodated in the vacuum chamber.
[0078]
The inside of the vacuum chamber is again 1 × 10 ^-4 After evacuation to about Pa, Ar gas was introduced into the vacuum chamber at a gas pressure of about 0.1 to 0.8 Pa, and the Tb target and the FeCo target were simultaneously sputtered while rotating the substrate. Thus, a 50 nm thick TbFeCo film was formed as the recording holding layer 27. At this time, the power applied to the Tb target was 300 W, the power applied to the FeCo target was 1.5 W, and the film formation time was 8 seconds. Inside the TbFeCo film, ultrathin layers having a high Tb abundance ratio and ultrathin layers having a high abundance ratio of FeCo were alternately stacked with a thickness of about 0.5 nm.
[0079]
(Comparative sample 2-2)
In the comparative sample 2-2, the recording holding layer 27 was formed using a normal stationary facing type sputtering apparatus in which one target faces one disk substrate. A sample was manufactured under the same conditions as in Sample 2-1 except for the formation of the record holding layer 27.
[0080]
In the formation of the recording holding layer 27 of the comparative sample 2-2, first, a TbFeCo alloy target was set in a vacuum chamber, and the inside of the vacuum chamber was 5 × 10 ^-5 It was evacuated to about Pa. The disk substrate 21 on which the first dielectric layer 22, the reproducing layer 23, the domain wall motion layer 24, the first intermediate layer 25, and the second intermediate layer 26 were formed was accommodated in the vacuum chamber.
[0081]
The inside of the vacuum chamber is again 1 × 10 ^-4 It was evacuated to about Pa and Ar gas was introduced into the vacuum chamber at a gas pressure of about 0.1 to 0.8 Pa. By performing sputtering of the TbFeCo alloy target, a 50 nm thick TbFeCo film was formed as the recording holding layer 27. At this time, the power applied to the TbFeCo alloy target was 1 kW, and the deposition time was 6 seconds. In Comparative Sample 2-2, since an alloy target was used, no periodic structure was formed inside the TbFeCo film.
[0082]
(Reproduction of magneto-optical recording medium)
Recording information was recorded and reproduced on the magneto-optical recording medium manufactured as described above. The writing of the information signal to the recording holding layer 27 was performed by modulating the external magnetic field while irradiating the magneto-optical recording medium with a laser beam, similarly to the conventional magneto-optical recording medium. An information signal with the shortest mark length of 0.2 μm was written to Sample 2-1 and Comparative Sample 2-2.
[0083]
FIG. 8 shows the reproduction power (Pr) dependence of the bit error rate (bER) as the reproduction characteristic of sample 2-1. The bottom value of the bit error rate of sample 2-1 is 3 × 10 ^-5 Was obtained. On the other hand, in the comparative sample 2-2, the bit error rate could not be measured due to poor reproduction characteristics.
[0084]
Next, an information signal having a mark length of 0.2 μm was written on the recording holding layer, and C / N measurement was performed. The C / N of Sample 2-1 was 42 dB, and the recording marks were stably held on the recording holding layer 27 because the anisotropic energy of the recording holding layer 27 was large. On the other hand, the C / N of Comparative Sample 2-2 was 30 dB. Therefore, it can be seen that the recording mark could not be held in the recording holding layer of the comparative sample 2-2.
[0085]
From the above results, according to the method of manufacturing a magneto-optical recording medium according to the present invention, a multilayer multilayer film having a periodicity of a rare earth element and a transition metal can be formed, and the magneto-optical recording of a magneto-optical recording medium using a DWDD method is It can be seen that the anisotropic energy of the layer can be increased. According to the method for manufacturing a magneto-optical recording medium and the sputtering apparatus according to the present invention, a magneto-optical recording medium for high-density recording that can obtain good recording and reproducing characteristics can be manufactured in a short time.
[0086]
Further, as shown in FIG. 5, for example, a laminated multilayer film having a periodicity of a rare earth element and a transition metal can be formed continuously with other layers, so that the productivity of the magneto-optical recording medium is high. Further, since a magneto-optical recording layer having high anisotropic energy can be formed using a small target, a magneto-optical recording medium having a high recording density can be manufactured at low cost.
[0087]
(Example 3)
The film thickness uniformity when the magneto-optical recording layer is formed by the sputtering apparatus according to the present invention will be described with reference to FIGS. 9 and 10 show examples in which a TbFeCo film having a thickness of 50 nm is formed on a disk substrate having a diameter of 64 mm. FIG. 9 shows the gas pressure dependence of the film thickness distribution. FIG. 10 shows the dependency of the film thickness distribution on the distance between the target and the substrate (between the TS).
[0088]
In the case of the self-revolution type sputtering apparatus, since the particles from the target enter the entire disk substrate, the film thickness can be relatively easily made uniform regardless of the film forming conditions. On the other hand, in the case of the sputtering apparatus according to the present invention, since the density of particles incident from the target to the disk substrate has a distribution (see FIG. 3), it is necessary to adjust the film forming conditions and the distance between TS.
[0089]
By appropriately controlling the film forming conditions such as the gas pressure, the distance between TSs, and the like, sufficient film thickness uniformity can be ensured even in the stationary facing single-wafer sputtering apparatus according to the present invention. The distance between the TSs was the distance between the center of the target and the disk substrate. The film thickness distribution is acceptable if it is within ± 2%, for example.
[0090]
In the example of FIG. 9, the distance between the TSs is fixed at 52 mm, and the gas pressure of the Ar gas introduced into the vacuum chamber is changed between 0.1 Pa and 0.3 Pa. In this case, when the gas pressure is 0.1 Pa, a sufficient thickness uniformity is obtained, and when the gas pressure is 0.3 Pa, the variation in the film thickness is large in a portion near the edge of the disk substrate. However, by changing other conditions such as the distance between TSs and the diameter of the target, it is also possible to secure a sufficient film thickness uniformity at a gas pressure of 0.3 Pa.
[0091]
In the example of FIG. 10, the gas pressure was kept constant at 0.1 Pa, and the distance between TS was changed between 52 mm and 58 mm. In this case, sufficient film thickness uniformity was obtained both when the distance between TSs was 52 mm and when the distance between TSs was 58 mm. As described above, by optimizing the film forming conditions such as the gas pressure, the distance between TSs, and the like, a sufficient film thickness uniformity can be ensured even in the sputtering apparatus according to the present invention.
[0092]
Embodiments of the method of manufacturing a magneto-optical recording medium and the sputtering apparatus of the present invention are not limited to the above description. For example, the method of manufacturing the magneto-optical recording medium of the present invention is a DWD (double masked detection detection) method, a FAD (front aperture detection) method, a DWD super image method other than a CAD (centre aperture detection) method, and the like. The present invention may be applied to formation of a magneto-optical recording layer of a magneto-optical recording medium to be used.
[0093]
The sputtering device is not limited to the DC magnetron sputtering device, but may be an RF (high frequency) magnetron sputtering device or a sputtering device other than the magnetron sputtering device. Further, the diameter of the disk substrate is not limited to the above example, and the present invention can be applied to disk substrates having different diameters by changing the diameter of the target and the like. In addition, various changes can be made without departing from the spirit of the present invention.
[0094]
【The invention's effect】
According to the method for manufacturing a magneto-optical recording medium of the present invention, a magneto-optical recording medium having a high recording density using a magnetic super-resolution technique such as magnetic domain expansion or domain wall motion can be manufactured with high productivity. According to the sputtering apparatus of the present invention, a magneto-optical recording film having high anisotropic energy can be formed in a short time.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a method for manufacturing a magneto-optical recording medium according to the present invention.
FIG. 2 is a plan view of a target and a disk substrate of FIG. 1;
FIG. 3 is a diagram showing a distribution of particles incident on a disk substrate from the target of FIG. 1;
FIG. 4 is a discharge time chart of a plurality of targets in the method of manufacturing a magneto-optical recording medium according to the present invention.
FIG. 5 is a top view showing an example of the configuration of an apparatus used in the method of manufacturing a magneto-optical recording medium according to the present invention.
FIG. 6 is a sectional view of a sample according to Example 1 of the present invention.
FIG. 7 is a sectional view of a sample according to a second embodiment of the present invention.
FIG. 8 is a diagram showing reproduction characteristics of the magneto-optical recording medium according to the second embodiment of the present invention.
FIG. 9 is a diagram showing a film thickness distribution of a magneto-optical recording medium according to Example 3 of the present invention.
FIG. 10 is a diagram showing a film thickness distribution of a magneto-optical recording medium according to a third embodiment of the present invention.
FIG. 11 is a schematic view of a revolving-type sputtering apparatus used in a conventional method of manufacturing a magneto-optical recording medium.
FIG. 12 is a schematic view of a stationary facing single-wafer sputtering apparatus used in a conventional method of manufacturing a magneto-optical recording medium.
[Explanation of symbols]
DESCRIPTION OF REFERENCE NUMERALS 1: stationary facing single-wafer sputtering apparatus, 2, 2A: vacuum chamber, 3: substrate holder, 4: disk substrate, 5: substrate rotation mechanism, 6: axis, 7, 7a, 7b: target, 8: disk substrate Loading / unloading section, 9: expansion / contraction section, 10: voltage application mechanism, 11: silicon substrate, 12: first dielectric layer, 13: magneto-optical recording layer, 14: second dielectric layer, 21: disk substrate, 22 .., A first dielectric layer, 23, a reproducing layer, 24, a domain wall displacement layer, 25, a first intermediate layer, 26, a second intermediate layer, 27, a recording holding layer, 28, a recording auxiliary layer, 29, a second dielectric Layer, 30: Thermal diffusion layer, 31: Protective film, 40: Rotating revolving type sputtering apparatus, 41: Substrate carrier, 42: Disk substrate, 43: Revolving axis, 44: Rotating axis, 45a to 45d: Target, 50: Stationary Opposing single-wafer sputtering apparatus, 51: vacuum chamber, 52: disk Plate, 53,53A～53c ... target, 54 ... substrate holder, 55 ... substrate rotation mechanism, 56 ... shaft.

Claims (8)

A first step of fixing a plurality of targets so that a plurality of targets made of different materials and one substrate face each other, and fixing a center position of the substrate;
A second step of rotating the substrate and performing sputtering while independently applying a voltage to the plurality of targets to form a magneto-optical recording layer made of a magnetic material on the substrate. Production method. 2. The method of manufacturing a magneto-optical recording medium according to claim 1, wherein in the second step, a voltage is continuously and simultaneously applied to the plurality of targets. 2. The method according to claim 1, wherein in the second step, a voltage is alternately applied to the plurality of targets. 4. The method for manufacturing a magneto-optical recording medium according to claim 3, wherein the voltage application time per time is set to an integral multiple of the rotation period of the substrate. 2. The method for manufacturing a magneto-optical recording medium according to claim 1, wherein the plurality of targets include a first target made of a magnetic material containing a rare earth element and a second target made of a magnetic material containing a transition metal. At least one of the first target and the second target contains both a rare earth element and a transition metal, and the abundance ratio between the rare earth element and the transition metal in the target is such that the first target and the second target are present. 6. The method for manufacturing a magneto-optical recording medium according to claim 5, wherein In the first step, a first magnetic layer to which at least a part of the magnetization of the magneto-optical recording layer is transferred, and a Curie temperature higher than the first magnetic layer formed on the first magnetic layer. The second substrate having a low second magnetic layer to a plurality of the targets,
2. The magneto-optical recording medium according to claim 1, wherein, in the second step, a third magnetic layer having a higher Curie temperature than the second magnetic layer is formed as the magneto-optical recording layer on the second magnetic layer. Manufacturing method. A vacuum chamber,
Target fixing means for fixing a plurality of targets in the vacuum chamber,
A substrate holding unit that holds one substrate in the vacuum chamber so as to face the plurality of targets fixed to the target fixing unit, fixes the center position of the substrate, and rotates the substrate.
A voltage applying means for independently applying a voltage to the plurality of targets.

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