JP2000339784A - Film-forming method and method and device for manufacturing optical disk - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a thin film having a uniform thickness even though there is a difference of the surface level between a land part and a groove part by sputtering a target in an atmosphere of a rare gas to form a thin film, irradiating a substrate with ionized particles to react the thin film with the ionized particles on the substrate and repeating both steps alternately. SOLUTION: A film-forming operation comprising steps of attaching a substrate to a substrate holder 5 within a vacuum chamber 1, evacuating the vacuum chamber 1 with a vacuum pump 2 and applying an RF voltage to an Si target and a nitriding operation comprising a step of irradiating with nitrogen gas are carried out to form a silicon nitride film. Then argon gas is introduced into the vacuum chamber 1 and a magnetic film is formed as a recording layer utilizing an alloy target consisting of TbFeCo. Further, a silicon nitride protective film is formed by the same method as the method by which a base layer is film-formed within the vacuum chamber 1 in which the base layer is film- formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical disk capable of recording information on both a land portion and a groove portion, and more particularly to a method for forming a thin film as a component of an optical disk by sputtering. About.

[0002]

2. Description of the Related Art Information can be recorded at high density.
In addition, optical discs capable of high-speed reproduction have attracted attention as applications for audio and images, and as recording media for computers. Read-only CDs are widely used for audio and computers. Also, a write-once type in which information can be recorded only once and a rewritable type (re-writable type) in which information once recorded can be rewritten many times have become widespread. In particular, a magneto-optical disk, which is one type of rewritable type, is capable of rewriting information more than one million times, and is becoming popular mainly as a recording medium for computers.

[0003] Optical discs are classified according to their recording principle into a magneto-optical type in which information is recorded in the form of magnetization and a phase change type in which information is recorded in a crystalline or non-crystalline form. A guide for guiding a laser beam emitted from an optical pickup of a recording / reproducing apparatus along an information sequence, that is, for tracking, is formed in the optical disk in a spiral shape in a concave or convex shape. This concave or convex guide is called a guide groove. In the ISO standard, a concave portion, that is, a far side when viewed from the pickup is called a land, and a convex portion, that is, a near side when viewed from the pickup is called a groove. Conventionally, information is recorded on either a land or a groove. Recording on a land is called a land recording method, and recording on a groove is called a groove recording method. The distance from the center of the land to the center of the adjacent land or the distance from the center of the groove to the center of the adjacent groove is called a track pitch.

In recent years, the number of opportunities for recording image files on an optical disk has increased, and accordingly, there has been an increasing demand for increasing the recording capacity of the optical disk. That is, there is an increasing demand for increasing the recording density of optical disks. To increase the recording density of the optical disk, it is effective to reduce the track pitch. Of course, for this purpose, it is necessary to reduce the recording mark width. Conventional track pitch is 1.6μm
Was a standard, but recently, 1.4 μm and 1.2 μm,
A narrow track pitch of 1.0 μm has been proposed.

[0005] However, when the track pitch is reduced, a phenomenon (referred to as optical crosstalk) occurs in which information written in adjacent tracks is simultaneously read.
In addition, since a tracking error signal required for tracking becomes considerably small, there arises a problem that accurate tracking becomes difficult. << Appearance of L / G recording method >> Accordingly, a land-groove recording method has been proposed as another approach for recording information at high density. This is because information has been recorded only on either the land or the groove, but by recording information on both the land and the groove, the track pitch is reduced by half and the recording density is increased. That is. For example, when the distance from the center of a land (or groove) to the center of an adjacent land (or groove) is 1.4 μm, by performing recording on both the land and the groove, the track pitch becomes 0.7 μm and the recording density is substantially reduced. Can be doubled.

In this method, if the groove depth is set to an appropriate value, it is possible to prevent information on adjacent groove (land) tracks from being simultaneously read during reproduction of a land (groove) track. That is,
Optical crosstalk can be prevented from occurring. In addition, since the distance between the centers of the lands (or grooves) is not small, the tracking error signal can secure a sufficient magnitude. << Cross erase problem >> As described above, to prevent optical crosstalk and maintain the tracking error signal,
A temporary solution is possible. However, in the optical recording, the information is recorded or erased on the track by the heat of the laser beam regardless of the magneto-optical type or the phase change type. Therefore, as the track pitch becomes smaller, the degree of heat generated when recording or erasing data on a certain track increases the temperature of an adjacent track increases. And
Eventually, there is a problem that information on an adjacent track is erased (referred to as cross erase or thermal crosstalk). This cross erase determines how narrow the track pitch can be. Conventional optical discs with a step of about 40-80 nm between the land and groove are about 0.8 μm for the magneto-optical type and phase change type, and 0.9-1.0 μm for the optical modulation overwrite magneto-optical type.
To the extent that it was the limit, narrower tracks were considered difficult. << Appearance of DG >> To solve this problem, a deep groove (JP-A-9-161321) has been proposed. That is, the distance of heat transfer is increased by increasing the step between the land and the groove, thereby reducing the amount of heat transfer to an adjacent track.

[0007] Generally, an optical disk has a layer (hereinafter, referred to as a layer) that functions to record one or more layers of information on a transparent substrate on which projections and depressions corresponding to lands and grooves are formed in advance.
A recording layer) and a dielectric layer for protecting this layer are laminated, and a protective layer of resin is further formed thereon. These recording layers and dielectric layers are formed by sputtering. Sputtering is a method in which the surface of a target placed in a vacuum chamber is struck out as fine particles with argon ions, and the particles are attached to a substrate to form a thin film. The particles hit by the argon ions scatter radially. Therefore, particles flying from various angles adhere to the substrate. << Dielectric Sputtering >> Materials such as silicon nitride, zinc sulfide, and tantalum oxide are used for the dielectric layer. For example, when sputtering silicon nitride, there are two methods.
One method is to form a silicon nitride film on a substrate by reacting silicon and nitrogen by sputtering using a target containing only silicon and a gas in which a nitrogen gas is mixed with an argon gas. The composition of silicon nitride to be formed can be adjusted by the amount of nitrogen gas to be mixed. This method is called reactive sputtering or reactive sputtering. The other is a method of forming a film using a silicon nitride target. This method can also adjust the composition of silicon nitride formed on the substrate by mixing a small amount of nitrogen gas with argon gas.

In order to increase the recording density of an optical disk,
The width of the mark to be recorded may be reduced, and the length of the mark to be recorded may be reduced. Record very small marks,
Attempting to reproduce this will result in reproducing a plurality of marks at one time (crosstalk) with the conventional reproducing beam size. Therefore, a necessary reproduction signal cannot be obtained.
Therefore, a magnetic layer called a reproduction layer is provided separately from the memory layer to mask the information recorded in the memory layer, and the memory is stored only in a part of the temperature range of the temperature distribution generated by the irradiation of the reproduction beam. A technique has been proposed in which the magnetization of a layer is transferred to a reproducing layer for reproduction. This is called magnetic super-resolution reproduction (MSR). Japanese Patent Application Laid-Open Nos. 9-320141 and 6-290496 propose a method of reproducing a mark recorded small by enlarging it only during reproduction by magnetic domain expansion or domain wall movement.

[0009]

By the way, a step between a land portion and a groove portion is formed on the surface of the optical disk substrate, and the particles hit from the target during sputtering are blocked by the land portion. In addition, a phenomenon occurs that it is difficult to adhere to the groove portion. When the step between the land portion and the groove portion is small as in a conventional optical disk, this phenomenon is not remarkable, so that it does not cause a serious problem. However, this phenomenon becomes more pronounced as the step between the land and the groove increases. FIG. 3 shows a state in which a film is formed on a deep groove optical disk. L in FIG. 3 represents a land portion, and G represents a groove portion. In the case of sputtering, particles fly from the upper side of the figure, adhere to the substrate surface, and compare with the thickness of the thin film formed on the land (L).
The thin film formed in the groove portion (G) becomes considerably thin.

[0010] As in the optical disk shown in FIG. 3, when the difference in film thickness between the land and the groove increases, the difference in heat capacity increases. Even if such a disk is irradiated with a beam of the same intensity, the temperature reached at the irradiated portion differs greatly between the land portion and the groove portion. Therefore, if recording is performed on the land portion and the groove portion with the same beam intensity, the thickness and length of the recording mark will differ. In order to record marks of the same size on the land portion and the groove portion of the optical disc, it is necessary to set different beam intensities between the land portion and the groove portion. This problem is the same not only in recording but also in erasing, and there arises a problem that the intensity of the erasing beam must be changed between the land portion and the groove portion.

In an optical disk in which a medium for reproducing a mark recorded by MSR or magnetic domain expansion or domain wall movement on a deep groove substrate is formed, a difference in film thickness affects a reproduction function. The normal reproduction operation may not be performed in the groove portion even if the normal reproduction operation is performed in the groove portion. An object of the present invention is to provide a method and an apparatus for forming a thin film having a uniform thickness regardless of a step between a land portion and a groove portion.

[0012]

In order to solve the above-mentioned problems, the invention according to the first aspect is characterized in that the surface has a width of 0.1 to 1.0.
In a film forming method for forming a dielectric film on a substrate having a spiral or concentric groove with a step of 80 to 600 nm having a step of 80 μm, (a) sputtering a target under a rare gas atmosphere to form a thin film Forming,
(B) By irradiating the substrate with ionized particles,
A step of reacting the ionized particles with the thin film on the substrate, and forming a dielectric film by alternately repeating the steps (a) and (b). This is a film forming method.

According to a second aspect of the present invention, in the film forming method according to the first aspect, any one of silicon, aluminum, and titanium is used as a target material in the step (a).
A film forming method characterized by using, as the ionized particles to be reacted with the thin film in the step (b), a gas obtained by ionizing any gas of a mixture of oxygen, nitrogen, hydrocarbon, ammonia and hydrogen.

According to a third aspect of the present invention, in the film forming method according to the first aspect, the thickness of the thin film formed in the step (a) is 0.1 nm or more and 0.7 nm or less. This is a film formation method characterized by the following. Further, the invention according to claim 4 has a depth of 80 to 60 on the surface of the transparent substrate.
2. The step (a) and the step (b) according to claim 1, wherein the magneto-optical disk substrate has a groove of 0 nm and can record information on both the land portion and the groove portion.
Is repeated to form a dielectric material.

According to a fifth aspect of the present invention, there is provided a vacuum chamber to which a vacuum pump is attached, a cathode to which a sputtering target can be attached, a power supply for applying a voltage to the target through the cathode, and a substrate to which a substrate can be attached. Holder, gas introduction part for introducing sputtering gas into vacuum chamber, ionized gas generation part for ionizing reactive gas, gas introduction part for introducing reactive gas, gas for controlling gas flow from gas introduction part A control unit, a pressure gauge, and a clock; (a) a step of forming a thin film by sputtering a target under a rare gas atmosphere; and (b) irradiating the substrate with ionized particles to form a thin film on the substrate. The process of reacting the thin film and the ionized particles in the process is alternately repeated to form the dielectric film. A film forming apparatus capable of.

The invention described in claim 6 is the same as the invention in claim 5
The film forming apparatus according to the above, a means for ionizing particles sputtered from the target between the substrate and the target, a means for applying a bias voltage connected to the substrate or the substrate holder, the particles sputtered at the time of sputtering Is a film forming apparatus capable of ionizing and sputtering while applying a bias voltage to the substrate.

The invention described in claim 7 is the first invention.
A method for manufacturing a magneto-optical disk, characterized in that the film forming method described in (1) is used for forming a dielectric of a magneto-optical disk having a plurality of magnetic layers. The invention described in claim 8 uses the invention described in claim 7 in a method for manufacturing a magneto-optical disk capable of reproducing information by magnetic super-resolution.

According to the ninth aspect of the present invention, there is provided
The present invention is used in a method for manufacturing a magneto-optical disk, wherein information is reproduced from a magnetic film which causes magnetic domain expansion or domain wall movement during reproduction.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. 1 includes a vacuum chamber 1, a vacuum pump 2, a gas introduction unit 3,
It comprises a cathode 4, a substrate holder 5, an RF power source 6 for discharge, a DC power source 7 for bias, and a pressure gauge 8. A target T is attached to the cathode 4 and a substrate S is attached to the substrate holder 5 inside the vacuum chamber 1. The vacuum pump 2 exhausts the air in the vacuum chamber 1 to lower the pressure. Further, the vacuum chamber 1 is provided with a plurality of gas introduction parts, and these can supply a sputtering gas and a reactive gas into the vacuum chamber 1. The discharge RF power source 6 applies an RF voltage to the target T through the cathode. The pressure gauge 8 measures the pressure in the vacuum chamber and sends the measured value to a control unit (not shown). A control unit (not shown) controls the amount of gas supplied by the gas introduction unit 3 based on the measurement value of the pressure gauge.

A method for forming a silicon nitride film on the surface of the substrate S will be described. First, an argon gas is attached to G1 as a sputtering gas, and a target made of silicon alone is attached to the cathode 4. When an RF voltage is applied to the silicon target through the cathode by the discharge RF power supply 6 while the argon gas is supplied by the gas introduction unit 3, the argon gas in a plasma state collides with the target surface and beats silicon particles. The silicon particles protruding from the target adhere to the surface of the substrate S attached to the substrate holder 5, and a thin film of silicon is formed on the substrate surface.

Next, the nitrogen gas of G2 is ionized in the ionized gas generating section 11 and introduced into the vacuum chamber 1. The ionized nitrogen gas reacts with silicon formed on the substrate to form a silicon nitride film. By alternately repeating the film formation by the sputtering of the silicon target and the nitridation of the formed silicon by irradiating with a nitrogen gas, a silicon nitride film having a sufficient thickness can be formed as an underlayer. . By forming the film by such a method, the film thickness of the formed silicon nitride is reduced as shown in FIG.
As shown in FIG. 7, a film having a small difference in thickness between the land (L) and the groove (G) is obtained.

The reason why the difference in film thickness between the land portion and the groove portion is reduced can be explained as follows. In conventional sputtering while introducing a reactive gas into a vacuum chamber, Si particles struck out of a target by an argon gas are scattered by the reactive gas, so that the number of particles incident on the substrate in an oblique direction increases. Particles obliquely incident on the substrate are blocked by the land in front of the substrate, making it difficult to reach the groove. As a result, the thickness of the groove is reduced, and the film between the land and the groove is formed. Increase the thickness difference. On the other hand, in the disk manufacturing method according to the embodiment, no reactive gas is introduced when sputtering the Si target, so that the number of particles obliquely incident on the substrate does not increase.

Furthermore, sputtering using a Si target has a higher film forming speed than sputtering using a sintered body target such as Si3N4, so that the film forming time can be shortened.

[0024]

Example 1 A substrate having a photocurable resin layer having spiral tracks formed on a circular glass having a diameter of 86 mm was prepared. The depth of the track formed in the photocurable resin layer,
That is, the step between the land and the groove was 175 nm. The track width of both the land and the groove is 0.
It was 7 μm.

The substrate was mounted on a substrate holder in a vacuum chamber of the sputtering apparatus shown in FIG. 1, and the inside of the vacuum chamber was evacuated by a vacuum pump. At the completion of evacuation, the pressure gauge indicated 1 * 10-6 Torr. An Si target was attached to the cathode, argon gas was introduced from the gas inlet, and the pressure in the vacuum chamber was 3 * 10-3T
Sputtering was started in the state of orr. The substrate was rotated at a rotation speed of 100 rotations per minute from the start to the end of sputtering. A film forming step (a) in which only an argon gas is introduced into a vacuum chamber and an RF voltage is applied to a Si target during one rotation of the substrate, and a step (a).
By alternately repeating the nitriding step (b) by irradiating ionized nitrogen gas to the surface of the film formed in the above, a silicon nitride film having a thickness of 75 nm was formed.

Next, the substrate was moved to another vacuum chamber, and a magnetic film made of TbFeCo was formed as a recording layer. For film formation, introduce argon gas into the vacuum chamber,
Tb ₂₁ Fe ₆₃ Co at a pressure of 5 * 10−3 Torr
₁₆ (subscript: atomic percentage) was performed using an alloy target to form a recording layer having a thickness of 100 nm. Further, the substrate was moved to a vacuum chamber on which an underlayer was formed, and a silicon nitride protective film having a thickness of 70 nm was formed by the same method as that for the underlayer.

The produced disk was mounted on a recording / reproducing apparatus, and a recording / reproducing test was performed. The recording / reproducing apparatus had a head laser beam wavelength of 680 nm and a head numerical aperture of 0.55. The substrate was rotated at 2800 rpm (2800 revolutions per minute), and the land was initialized by applying a 9 mW laser beam to the land near a radius of 30 mm while applying a magnetic field of 300 Oe by an electromagnet attached to the apparatus. Next, the groove portion was initialized by applying a 9 mW laser beam to the groove portion near a radius of 30 mm while applying a magnetic field of 300 Oe.

Next, a mark was recorded on each of the land portion and the groove portion having a radius of about 30 mm while changing the laser beam intensity at the time of recording, and the optimum recording power was obtained.
While applying a magnetic field of 300 Oe in a direction opposite to that of the initialization as a recording magnetic field, 3.75 MHz and a duty ratio of 5
Recording was performed while modulating the laser beam intensity at 0%. The recorded marks were reproduced by irradiating an unmodulated laser beam with a laser beam intensity of 1 mW. The reproduced signal was analyzed by a spectrum analyzer, and the power at which the second harmonic became maximum was determined as the optimum recording power. The optimum recording power at the land was 8.8 mW, and the optimum recording power at the groove was 8.5 mW. Thus, it was confirmed that there was almost no difference in recording sensitivity between the land portion and the groove portion.

[0029]

Example 2 A circular glass substrate having a diameter of 86 mm was prepared.
A 75-nm-thick silicon nitride film was formed in the same process as in Example 1. The substrate was moved to another vacuum chamber, and a magnetic film made of GdFeCo was formed as a reproducing layer. Argon gas is introduced into the vacuum chamber and the pressure is 5 * 10
By performing sputtering using a Gd ₂₅ Fe ₆₀ Co ₁₅ (subscript is an atomic percentage) alloy target at −3 Torr, a reproducing layer having a thickness of 30 nm was formed. Next, the substrate was moved to another vacuum chamber, and a magnetic film made of GdFe was formed as an intermediate layer. For film formation, argon gas was introduced into the vacuum chamber, and the pressure was 5 * 10-3T.
Gd29Fe71 at orr (subscript is atomic percentage)
An intermediate layer having a thickness of 50 nm was formed using an alloy target. Next, the substrate was moved to another vacuum chamber, and a magnetic film made of TbFeCo was formed as a recording layer. For film formation, introduce argon gas into the vacuum chamber,
Tb ₂₁ Fe ₆₃ Co at a pressure of 5 * 10−3 Torr
₁₆ (subscript: atomic percentage) was performed using an alloy target to form a recording layer having a thickness of 50 nm. Further, the substrate was moved to a vacuum chamber on which an underlayer was formed, and a silicon nitride protective film having a thickness of 70 nm was formed by the same method as that for the underlayer. A vertical sectional view of the disk thus manufactured is shown in the lower part of FIG.

As in Example 1, initialization was performed by irradiating a 9 mW laser beam while applying a magnetic field of 300 Oe to the lands and grooves near a radius of 30 mm. While applying a magnetic field of 300 Oe in a direction opposite to that of the initialization, a land portion and a land portion are irradiated by irradiating a laser beam intensity-modulated between 8.7 mW and 2.5 mW at a frequency of 15 MHz and a duty ratio of 30%. A mark was recorded in the groove.

The optimum reproducing power was determined by reproducing the mark while changing the intensity of the laser beam to be reproduced while applying a magnetic field of 300 Oe to the area where the mark was recorded in the same direction as during initialization. The disk manufactured in this embodiment is capable of reproducing marks recorded by magnetic super-resolution, and the state of magnetization when reproduced at the optimum reproducing power is shown in the vertical sectional view at the bottom of FIG. The state seen from the irradiation side is shown in the upper part of FIG. When reproduction is performed with the optimum reproduction power, only the middle temperature area 44 becomes an opening from which a recorded mark can be read, and reproduction with higher resolution than a reproduction spot becomes possible. The optimal playback power is
The reproduced signal was analyzed by a spectrum analyzer and the power at which the C / N was maximized was determined. The optimum reproducing powers of the land portion and the groove portion were 3.0 mW and 2.8 mW, respectively. In this way, it was confirmed that there was almost no difference in reproduction power between the land portion and the groove portion when reproducing with magnetic super-resolution.

[0032]

Embodiment 3 FIG. 6 shows the structure of a sputtering apparatus used for forming a dielectric layer according to this embodiment. Substrate holder 5
, Eight substrates can be attached, and film formation on eight substrates can be performed at the same time. A partition 10 and a gas introduction unit 9 for introducing nitrogen gas are provided on the same side of the vacuum chamber as the cathode 4. The center of the target T attached to the cathode 4 is arranged outside the center of the substrate holder 5. When sputtering is performed while rotating the substrate holder, a film is formed on the substrate surface by sputtering when the substrate is located on the target side of the partition, and a film is formed when the substrate is located on the opposite side of the target with respect to the partition. Not done. By performing sputtering while rotating the substrate holder, a film on the substrate surface is formed at regular intervals.

Eight circular substrates having the same grooves as in Example 1 were prepared, attached to a substrate holder, and the inside of the vacuum chamber was evacuated by a vacuum pump. At the completion of evacuation, the pressure gauge indicated 1 * 10-6 Torr. An Si target is attached to the cathode, and an argon gas is introduced from the gas introduction unit 3 while simultaneously introducing an ionized nitrogen gas from the gas introduction unit 9 while the pressure in the vacuum chamber is 3 * 10 −.
Sputtering was started at 3 Torr. The substrate holder was rotated at a rotation speed of 60 rotations per minute. By sputtering in such a state, the substrate becomes Si
The Si film formation step (a) using the target and the nitridation step (b) using ionized nitrogen gas were alternately repeated, and a silicon nitride film having a thickness of 75 nm was finally formed.

Next, the substrate was moved to another vacuum chamber, and a magnetic film made of TbFeCo was formed as a recording layer. For film formation, introduce argon gas into the vacuum chamber,
Tb ₂₁ Fe ₆₃ Co at a pressure of 5 * 10−3 Torr
₁₆ (subscript: atomic percentage) was performed using an alloy target to form a recording layer having a thickness of 100 nm. Further, the substrate was moved to a vacuum chamber on which an underlayer was formed, and a silicon nitride protective film having a thickness of 70 nm was formed by the same method as that for the underlayer.

The prepared disk was mounted on a recording / reproducing apparatus, and a recording / reproducing test was performed under the same conditions as in Example 1. It was confirmed that there was almost no difference in recording sensitivity between the land portion and the groove portion.

[0036]

Embodiment 4 FIG. 9 shows the structure of a sputtering apparatus used for forming a dielectric layer in this embodiment. Substrate holder 5
Is connected to a bias power supply 7, and a high frequency coil is provided around the target T as shown in FIG.
By applying a bias electric field to the substrate holder, the silicon particles ionized by the high-frequency coil are attracted vertically to the substrate, reducing the effect of shielding by the land and reducing the film thickness of the land and groove. Be transformed into

Eight circular substrates having the same grooves as those in Example 1 were prepared, mounted on a substrate holder, and the inside of the vacuum chamber was evacuated by a vacuum pump. At the completion of evacuation, the pressure gauge indicated 1 * 10-6 Torr. An Si target is attached to the cathode, and an argon gas is introduced from the gas introduction unit 3 while simultaneously introducing an ionized nitrogen gas from the gas introduction unit 9 while the pressure in the vacuum chamber is 3 * 10 −.
Sputtering was started at 3 Torr. While applying a bias voltage of 100 W to the substrate holder,
It was rotated at the rotation speed of rotation. Further, sputtering was performed while applying a voltage of 250 W to a high-frequency coil attached around the silicon target. By sputtering while rotating the substrate holder,
On the substrate, a silicon film formation step (a) using a silicon target and a nitridation step (b) using ionized nitrogen gas are alternately repeated.
A silicon nitride film having a thickness of m was formed.

Next, the substrate was moved to another vacuum chamber, and a recording layer made of TbFeCo was formed under the same conditions as in Example 3. Further, the substrate was moved to a vacuum chamber on which an underlayer was formed, and a silicon nitride protective film having a thickness of 70 nm was formed by the same method as that for the underlayer. The produced disk was mounted on a recording / reproducing apparatus, and a recording / reproducing test was performed under the same conditions as in Example 1. As a result, it was confirmed that there was almost no difference in recording sensitivity between the land portion and the groove portion.

[0039]

As described above, according to the first aspect of the present invention, the step between the land portion and the groove portion is 80-80.
When manufacturing a disk having a step difference of 600 nm, which is larger than a conventional magneto-optical disk, it is possible to manufacture a magneto-optical disk having a small difference in film thickness between a land portion and a groove portion.

According to the second aspect of the present invention, it is possible to form a dielectric such as silicon nitride or aluminum nitride having a small difference in film thickness between the land and the groove. According to the third aspect of the present invention, by setting the thickness of the thin film formed in the step (a) to 0.7 nm or less, the difference in film thickness between the land portion and the groove portion is small, and the dielectric material having good optical characteristics. A film can be formed.

According to the fourth aspect of the present invention, there is provided a magneto-optical disk capable of recording information on both a land portion and a groove portion, and a magneto-optical disk having a small difference in film thickness between the land portion and the groove portion. It can be manufactured. A step between a land portion and a groove portion is formed by forming a dielectric film by the apparatus according to claim 5.
When a disk having a step difference of 0 nm and a step larger than that of the conventional magneto-optical disk is manufactured, a magneto-optical disk having a small difference in film thickness between the land portion and the groove portion can be manufactured.

In the apparatus according to the sixth aspect, in addition to the film forming apparatus according to the fifth aspect, it is possible to ionize particles sputtered during sputtering and perform sputtering while applying a bias voltage to the substrate. Membrane device,
Further, it is expected that the difference in film thickness between the land portion and the groove portion is reduced. According to a seventh aspect of the present invention, the film forming method according to the first aspect is used for forming a dielectric of a magneto-optical disk having a plurality of magnetic layers, so that the film thickness of the land portion and the groove portion is increased. This makes it possible to manufacture a magneto-optical disk having a small difference between the two.

According to an eighth aspect of the present invention, there is provided a method of manufacturing a magneto-optical disk capable of reproducing information by magnetic super-resolution using the invention of the seventh aspect.
Good reproduction characteristics are realized by the land portion and the groove portion. According to a ninth aspect of the present invention, there is provided a method for manufacturing a magneto-optical disk, wherein information is reproduced from a magnetic film which causes magnetic domain expansion or domain wall movement during reproduction. Good reproduction characteristics are realized by the land portion and the groove portion.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a sputtering apparatus of the present invention.

FIG. 2 is a vertical sectional view showing the thickness of a thin film of an optical disk manufactured by the manufacturing method of the present invention.

FIG. 3 is a vertical sectional view showing the thickness of a thin film of an optical disk manufactured by a conventional manufacturing method.

FIG. 4 is a vertical sectional view of the magneto-optical disk according to the first embodiment of the present invention.

FIG. 5 is a vertical sectional view of a magneto-optical disk according to a second embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of a sputtering apparatus according to a third embodiment.

FIG. 7 is a diagram illustrating an arrangement of a target and a nitrogen gas introduction unit of a sputtering apparatus according to a third embodiment.

FIG. 8 is a diagram illustrating an arrangement of a substrate holder and a substrate of a sputtering apparatus according to a third embodiment.

FIG. 9 is a diagram illustrating a configuration of a sputtering apparatus according to a fourth embodiment.

FIG. 10 is a diagram showing an arrangement of a target and a nitrogen gas introduction unit of a sputtering apparatus according to a fourth embodiment.

FIG. 11 is a diagram showing an arrangement of a substrate holder and a substrate of a sputtering apparatus according to a third embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Vacuum chamber 2 ... Vacuum pump 3 ... Gas introduction part 4 ... Cathode 5 ... Substrate holder 6 ... RF power supply for discharge 7 ... DC power supply for bias 8 ... Pressure gauge 9 ... Gas introduction part (for reactive gas) 10 ... Partition DESCRIPTION OF SYMBOLS 11 ... Ionized gas generation part 12 ... High frequency coil 21 ... Substrate 22 ... Underlayer 23 ... Recording layer 24 ... Protective layer 31 ... Substrate 32 ... Underlayer 33 ... Reproducing layer 34 ... Intermediate layer 35 ... Recording layer 36 ... Protective layer 41 ... Reproduction spot 42: heat-accumulated area 43: high-temperature area 44: medium-temperature area 45: low-temperature area 46: recording mark

Claims (9)

[Claims] 1. A surface having a width of 0.1 to 1.0 μm and a step 80
In a film forming method for forming a dielectric film on a substrate in which a spiral or concentric groove of about 600 nm is formed,
(A) a step of forming a thin film by sputtering a target in a rare gas atmosphere; and (b) a step of irradiating the substrate with ionized particles to cause the thin film to react with the ionized particles on the substrate. And forming a dielectric film by alternately repeating step (a) and step (b). 2. A thin film is formed by using any of silicon, aluminum and titanium as a target material in the step (a), and in the step (b), any one of a mixture of oxygen, nitrogen, hydrocarbon, ammonia and hydrogen is used. The film forming method according to claim 1, wherein the gas is ionized and reacted with the thin film formed in the step (a). 3. The film forming method according to claim 1, wherein
A film forming method, wherein the thickness of the thin film formed in the step (a) is 0.1 nm or more and 0.7 nm or less. 4. A depth of 80 to 600 nm on a surface of a transparent substrate.
A magneto-optical disk substrate that has a groove of which information can be recorded in both the land portion and the groove portion,
(A) forming a thin film by sputtering a target under a rare gas atmosphere; and (b) reacting the thin film with the ionized particles by irradiating the ionized particles. A method for manufacturing a magneto-optical disk, wherein a dielectric film is formed on a substrate by repeating (a) and step (b). 5. A vacuum chamber equipped with a vacuum pump, a cathode on which a sputtering target can be mounted, a power supply for applying a voltage to the target through the cathode, a substrate holder on which a substrate can be mounted, and a sputtering gas introduced into the vacuum chamber. Gas introduction section,
An ionized gas generator for ionizing a reactive gas,
It has a gas introduction part for introducing a reactive gas, a gas control part for controlling a gas flow rate from the gas introduction part, a pressure gauge and a clock, and (a) by sputtering a target under a rare gas atmosphere Forming a thin film;
(B) By irradiating the substrate with ionized particles,
A film forming apparatus capable of forming a dielectric film by alternately repeating a step of reacting a thin film and ionized particles on a substrate. 6. A device for ionizing particles sputtered from a target between a substrate and a target, and a device for applying a bias voltage connected to the substrate or the substrate holder, wherein the particles sputtered during sputtering are ionized. 6. The film forming apparatus according to claim 5, wherein sputtering can be performed while applying a bias voltage to the substrate. 7. A method for manufacturing a magneto-optical disk, wherein a dielectric film is formed by the film forming method according to claim 1, and then a plurality of magnetic films having different compositions are sequentially formed. A method of manufacturing a magneto-optical disk. 8. A method of manufacturing a magneto-optical disk according to claim 7, wherein said plurality of magnetic films are magnetic films capable of reproducing information by magnetic super-resolution. Disc manufacturing method. 9. A method for manufacturing a magneto-optical disk according to claim 7, wherein said plurality of magnetic films reproduce information from a magnetic film which causes magnetic domain expansion or domain wall movement during reproduction. Manufacturing method.