JP2000057640A - Production of optical information recording medium and producing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To mitigate the difference in film thickness by laminating and forming two or more thin films by using cathodes with at least one different condition among the distribution of a magnetic field on a target, the target size and the consumed amt. of the target to form at least one layer among multilayered films. SOLUTION: A single wafer sputtering device consists of a substrate feeding room 1, a first film forming chamber 2 for a lower dielectric layer, a second film forming chamber 3 for a lower dielectric layer, a film forming chamber 4 for a recording layer, a film forming chamber 5 for an upper dielectric layer, a film forming chamber 6 for a reflection layer and a substrate discharging chamber 7. In order to form the lower dielectric layer, two film forming chambers of the first and second film forming chambers 2, 3 for the lower dielectric layer are provided and both film forming chambers have different outer diameters of magnets from each other as 120 mm and 200 mm, respectively. In a film forming process of the lower dielectric layer, the substrate is passed through the first film forming chamber 2 for the lower dielectric layer and through the second film forming chamber 3 for lower dielectric layer in this order and in each of the film forming chambers, a ZnS-SiO2 film is formed to 60 nm thickness and laminated to obtain the total about 120 nm film thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for manufacturing an optical information recording medium for recording and reproducing information by irradiating a laser beam or the like.

[0002]

2. Description of the Related Art Optical information recording media such as optical discs have attracted attention as large-capacity, high-density memories.
The development of a rewritable so-called erasable medium is in progress. As such a medium, a thin film that can change phase between an amorphous state and a crystalline state is used as a recording layer,
2. Description of the Related Art There is known an information recording medium that records and erases information by using a phase change due to heat energy by laser light irradiation. Examples of the phase change material for the recording layer include Ge, Sb,
Alloy film mainly composed of Te, In, etc., for example, GeSbT
e alloys are known. Information is recorded by forming a mark by partially amorphizing the recording layer, and information is often erased by crystallization of the amorphous mark. Amorphization is performed by heating the recording layer to a temperature equal to or higher than the melting point and then cooling the recording layer at a speed equal to or higher than a predetermined value. On the other hand, crystallization is performed by heating the recording layer to a temperature equal to or higher than the crystallization temperature and equal to or lower than the melting point.

[0003] Dielectric layers are usually formed above and below the recording layer. The dielectric layer first protects the substrate from the heat of the recording layer, which instantaneously rises above its melting point, and, in order to prevent deformation and breakage of the recording layer, secondly, by utilizing the optical interference effect, Thirdly, in order to obtain a sufficient signal intensity at the time of reproduction, it is formed to realize a cooling rate suitable for forming a good amorphous mark shape. The properties required of dielectric materials to achieve these purposes are sufficient heat resistance,
Large refractive index, appropriate thermal conductivity, etc. Materials satisfying these conditions include, for example, ZnS—SiO ₂ and Si ₃
N ₄ are known.

[0004] The medium is often formed by forming a multilayer film in which a reflection layer, a diffusion prevention layer, and the like are added to a recording layer and a dielectric layer on a transparent substrate. The multilayer film formed on the substrate is, for example, a lower dielectric layer / recording layer / upper dielectric layer / reflective layer in order from the substrate side.

A multilayer film of such an optical information recording medium is generally formed by sputtering using an inert gas such as Ar gas. Film forming apparatuses are roughly classified into a batch type and a single wafer type. Here, the batch type is an apparatus in which a large number of substrates are arranged on one pallet, and a film is formed simultaneously in a large-capacity film formation chamber provided with a large sputtering target. On the other hand, the single-wafer method is an apparatus in which layers are stacked one by one in a small-capacity film formation chamber provided with a small sputtering target. Comparing these two methods, the single-wafer method is advantageous in terms of actual production because the equipment can be reduced in size and the target can be used efficiently.

[0006]

However, when a film is formed using a single-wafer type manufacturing apparatus, a film thickness difference is likely to occur at a position on a substrate, particularly in a radial direction of an optical disk. There has been a problem that variations in important characteristics such as recording quality and recording sensitivity cannot be reduced.

The present invention provides a method and an apparatus for manufacturing an optical information recording medium in which a difference in film thickness depending on a position on a substrate is small and a variation in reflectance and recording sensitivity is suppressed. The purpose is to:

[0008]

In order to achieve the above object, a method for manufacturing an optical information recording medium according to the present invention can cause an optically detectable state change on a transparent substrate by irradiation with a light beam. A method for manufacturing an optical information recording medium having a multilayer film including a recording layer, wherein at least one layer included in the multilayer film is formed by laminating two or more thin films having different film thickness distributions. It is characterized by.

By laminating two or more thin films having different film thickness distributions as described above, it is possible to reduce a difference in film thickness between layers included in the multilayer film.

In the method for manufacturing an optical information recording medium according to the present invention, two or more layers having different film thickness distributions are formed on at least one condition selected from a magnetic field distribution on a target, a target size, and a consumption amount of the target. Are preferably formed by magnetron sputtering using two or more cathodes different from each other.

According to this preferred example, the difference in film thickness can be effectively reduced in the magnetron sputtering method for forming a film using high-density plasma.

In the method for manufacturing an optical information recording medium according to the present invention, the multilayer film includes a dielectric layer in contact with the recording layer, and at least one of the dielectric layers has at least two dielectric layers having different thickness distributions. It is preferable to form by laminating thin films. This is because the uniformity of the thickness of the dielectric layer greatly affects various properties of the medium.

Further, in the method of manufacturing an optical information recording medium according to the present invention, a layer having a film thickness of λ / (6.4n) or more is formed by laminating two or more thin films having different film thickness distributions. Is preferred. Here, λ is the wavelength of the light beam used, and n is the refractive index of the thin film at the wavelength λ. As described above, the effect of the present invention is remarkable in a layer having a large thickness because the difference in the thickness tends to be large.

Further, the optical information recording medium manufacturing apparatus according to the present invention is directed to an optical information recording medium having a multilayer film including a recording layer which causes a state change that can be optically detected by irradiation of a light beam on a transparent substrate. An apparatus for manufacturing a recording medium, wherein a film forming chamber for magnetron sputtering for forming the multilayer film is continuously arranged, and two or more film forming chambers adjacent to each other are formed.
At least one selected from the magnetic field distribution on the target, the size of the target, and the consumption of the target is provided with different cathodes.

By arranging such a cathode in a film forming chamber and forming a film, a difference in film thickness between layers included in the multilayer film can be reduced.

In the apparatus for manufacturing an optical information recording medium of the present invention, it is preferable that two or more adjacent film forming chambers have a target made of the same material.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

FIG. 1 is an arrangement view of a film forming chamber and the like in an example of the manufacturing apparatus of the present invention. The single-wafer sputtering apparatus includes a substrate loading chamber 1, a lower dielectric layer first film forming chamber (hereinafter, simply referred to as a "first film forming chamber") 2, and a lower dielectric layer second film forming chamber ( Hereinafter, this is simply referred to as a “second film formation chamber”) 3, a recording layer film formation chamber 4, an upper dielectric layer film formation chamber 5, and a reflective layer film formation chamber 6.
And a substrate discharge chamber 7. The gas flow rate, pressure, discharge power, and time during sputtering in each of the film forming chambers 2, 3, 4, 5, and 6 are controlled by the controller 10.
Can be controlled to a predetermined value.

In the above-mentioned apparatus, two film forming chambers are prepared instead of one as in the prior art for forming the lower dielectric layer. As described above, with the use of the manufacturing apparatus of the present invention, the multilayer film can be formed by laminating at least one layer constituting the multilayer film in two or more film forming chambers arranged continuously. .

Each of the film forming chambers 2, 3, 4, 5, and 6 has a sectional structure shown in FIG. A cooling water channel 12 for preventing overheating of the target is arranged in the cathode 11,
Further, a detachable magnet 13 and a sputtering target 14 are provided. In each of the film forming chambers, a substrate 16 mounted on a substrate holder 15 is disposed at a position facing the target 14. The substrate holder 15 can transfer each film forming chamber from the substrate input chamber 1 to the substrate discharge chamber 7 by a transfer mechanism (not shown). The space between the target 14 and the substrate 16 is surrounded by a deposition-preventing plate 17, and the atmosphere and pressure in this space can be controlled from outside.

FIG. 3 shows an example of a cross-sectional configuration of a phase-change optical disk as an example of an optical information recording medium that can be manufactured by such a manufacturing apparatus. This disc-shaped medium has a lower dielectric layer 22 made of a ZnS-SiO ₂ thin film having a thickness of about 120 nm on a transparent substrate 21 having a center hole 30 and a guide groove (not shown), and a thickness of 20 nm. GeSb degree
Recording layer 23 made of Te alloy thin film, an upper dielectric layer 24 having a thickness made of ZnS-SiO ₂ thin film of about 30 nm, the reflective layer 25 having a thickness consisting of 150nm about Al alloy thin film is formed in this order. The optical disk shown in FIG.
The protective layer 2 is further formed on the multilayer film formed by sputtering via an adhesive layer 26 formed by applying an adhesive.
7, a resin substrate is provided.

Since the GeSbTe alloy has an extremely high crystallization speed, it can be made amorphous and crystallized only by modulating and irradiating the intensity of a single laser beam. Therefore, a medium using this material can rewrite information with a single laser beam called overwriting. In addition, the thickness of the dielectric layer is designed so that a sufficient signal intensity can be obtained at the time of reproduction due to an optical interference effect, and a cooling rate of the recording layer sufficient to form an amorphous mark having a good shape at the time of recording can be obtained. Have been.

However, the thickness and material of each layer are not limited to the above examples. For example, as the recording layer 23, GeSbTeSe, InSb, InSbTe,
An alloy such as nSbTeAg can be used. Also,
As the dielectric layers 22 and 24, SiO ₂ , SiO, Ti
O ₂ , MgO, Ta ₂ O ₅ , Al ₂ O ₃ , GeO ₂ , SiC,
ZnS, ZnSe, ZnTe, PbS, Ge ₃ N ₄ , Si
₃ N ₄ , SbN, BN, AlN and the like or a mixture of these compounds can be used. Further, as the reflection layer 25, a metal material such as Au, Cu, Cr, Ni, and Ti can be used.

The thickness difference between the respective layers is not particularly limited, but in order to make the properties of the optical information recording medium uniform, the wavelength of the light beam used is set to λ,
Assuming that the refractive index of the thin film at the wavelength λ is n, λ /
(64n) or less.

Hereinafter, a specific example of manufacturing an optical disk having a film configuration as shown in FIG. 3 using the apparatus described with reference to FIGS. 1 and 2 will be described. (First Embodiment) A magnet having an outer diameter of 120 mm is provided in the first film forming chamber 2, a magnet having an outer diameter of 200 mm is provided in the second film forming chamber 3, and an external magnet is provided in the other film forming chambers 4, 5 and 6. A disk-shaped magnet having a diameter of 160 mm was arranged. A target having an outer diameter of 200 mm was arranged in each of the first film forming chamber and the second film forming chamber.

From the substrate loading chamber 1, an outer diameter of 120 mm and a thickness of
0.6mm disc-shaped polycarbonate substrate in the device
The first film forming chamber 2 and the second film forming chamber 3
Only the partial dielectric layer was formed. In the first and second deposition chambers
Is formed by ZnS-SiO _TwoAr using target
It is performed in an atmosphere, and the film forming condition is a pressure of 5 mTorr.
r, discharge power 3 kW (RF). Note that each deposition chamber
The distance between the target 14 and the substrate 16 is 70 m
m.

The ZnS-SiO film thus formed is
The thickness of each of the _two thin films was 60 nm, and the total thickness was about 120 nm. FIG. 4 shows the thickness distribution of this thin film in the substrate radial direction. As shown in FIG. 4, the thickness difference of the dielectric thin film is 5
% Or less.

On the other hand, for comparison, a ZnS-SiO ₂ thin film was formed in the same manner as described above except that both the magnets disposed in the first and second film forming chambers had an outer diameter of 160 mm. This thin film showed a film thickness distribution as shown in FIG. 5, and the film thickness difference was 10% or more.

As described above, the recording layer and the like are further formed on the lower dielectric layer in which the film thickness difference is reduced to 5% or less by using the magnets having different diameters in the film forming chambers arranged continuously. A film was formed. All layers were formed in an Ar atmosphere similarly to the lower dielectric layer.

First, the recording layer was formed using a GeSbTe target, and the film was formed under a pressure of 1 mTo.
rr and discharge power 0.5 kW (DC). The film thickness of the GeSbTe thin film thus formed was 20 nm.

Next, an upper dielectric layer was formed on the recording layer.
Deposition of the upper dielectric layer is performed using ZnS-SiO ₂ target, the film forming conditions were a pressure 5 mTorr, discharge power 3 kW (RF). The thickness of the ZnS—SiO ₂ thin film thus formed was 30 nm.

Further, a reflection layer was formed on the upper dielectric layer. The reflective layer is formed using an Al target.
The film formation conditions are a pressure of 2 mTorr and a discharge power of 4 kW.
(DC). The thickness of the Al thin film thus formed was 150 nm.

By irradiating the optical disk thus obtained with laser light having a wavelength of 660 nm from the substrate side,
The reflectance was measured. The difference in reflectance in the radial direction of this optical disk was about 1%. For comparison, a recording layer, an upper dielectric layer, and a reflective layer were sequentially formed on the lower dielectric layer having a film thickness difference of 10% or more formed as described above. The difference in the reflectivity of the burned optical disc is about 3
%Met.

As described above, when the lower dielectric layer is formed, thin films having different film thickness distributions are stacked and formed by magnetron sputtering using two or more cathodes having different magnetic field distributions. The difference in reflectance in the obtained recording medium could be reduced.

In the above embodiment, magnets having different outer diameters are used. However, the magnetic field distribution on each target may be adjusted by changing the strength, arrangement, and the like of minute magnet pieces constituting the magnet.

(Second Embodiment) Except that the outer diameter of the target in the first film forming chamber was 120 mm, the outer diameter of the magnet was 120 mm, the outer diameter of the target in the second film forming chamber was 200 mm, and the outer diameter of the magnet was 200 mm. Then, a lower dielectric layer was formed in the same manner as in the first embodiment. As a result, the difference in the thickness of the lower dielectric layer could be suppressed to 5% or less as in the first embodiment.

On the lower dielectric layer, a recording layer, an upper dielectric layer, and a reflective layer were sequentially formed in the same manner as in the first embodiment to manufacture an optical disk. The difference in reflectance in the radial direction of this optical disk was about 1%.

(Third Embodiment) Except that the outer diameter of the target in the first film forming chamber was 120 mm, the outer diameter of the magnet was 160 mm, the outer diameter of the target in the second film forming chamber was 200 mm, and the outer diameter of the magnet was 160 mm. Then, a lower dielectric layer was formed in the same manner as in the first embodiment. As a result, the difference in the thickness of the lower dielectric layer could be suppressed to 5% or less as in the first embodiment.

On the other hand, both the target outer diameters are 200 mm.
A lower dielectric layer was formed in the same manner as described above except for the point described above. The difference in film thickness of the lower dielectric layer was 10% or more.

On the lower dielectric layer, a recording layer, an upper dielectric layer, and a reflective layer were sequentially formed in the same manner as in the first embodiment to manufacture an optical disk. Also in this case, it was confirmed that the difference in reflectance of the optical disk can be reduced by reducing the difference in film thickness of the lower dielectric layer.

As described above, when the lower dielectric layer is formed, the thin films having different film thickness distributions are stacked by using magnetron sputtering with different target sizes, thereby obtaining the recording medium obtained. The reflectivity difference could be reduced.

(Fourth Embodiment) First film forming chamber and second film forming chamber
In the film forming chamber, both the target outer diameter was 200 mm,
While the outer diameter of the magnet was set to 160 mm, the targets used in both the film forming chambers had different consumption amounts. That is, a target in which the erosion portion has been consumed to about 50% of the thickness of the target is disposed in the first film forming chamber, and an unused target is disposed in the second film forming chamber. . Except for this point, the lower dielectric layer was formed in the same manner as in the first embodiment. As a result, the difference in the thickness of the lower dielectric layer could be suppressed to 5% or less.

On the other hand, in both the first film forming chamber and the second film forming chamber, a target which has been consumed to the extent that the consumption of the erosion portion having the same consumption is about 50% of the target thickness is arranged. A lower dielectric layer was formed in the same manner as above except for the point described above. The thickness difference of this lower dielectric layer is
10% or more.

On the lower dielectric layer, a recording layer, an upper dielectric layer, and a reflective layer were sequentially formed in the same manner as in the first embodiment to manufacture an optical disk. Also in this case, it was confirmed that the difference in reflectance of the optical disk can be reduced by reducing the difference in film thickness of the lower dielectric layer.

As described above, when the lower dielectric layer is formed, the thin films having different thickness distributions are stacked and formed by magnetron sputtering using magnets having different consumption amounts of the target. The difference in reflectance in the recording medium to be obtained was able to be reduced.

In each of the above embodiments, only the lower dielectric layer is formed by laminating thin films in a plurality of film forming chambers. However, the present invention is not limited to the lower dielectric layer alone but is applied to the upper dielectric layer. A similar method may be applied to the formation of the dielectric layer and other layers.

The present invention is preferably applied to a layer in which 10% of the variation of the film thickness is equal to or more than the optical film thickness λ / (64n). Here, λ and n are the same as above. However, the dielectric layers provided above and below the recording layer, that is, the lower dielectric layer and the upper dielectric layer play an important role optically, and the variation in the film thickness of these layers depends on the reflectance of the medium. Have a great effect on In particular, since the lower dielectric layer is often formed to be thick, the influence of the film thickness distribution is large. Therefore, as exemplified above,
At least the lower dielectric layer is preferably formed by laminating a plurality of films.

[0048]

As described in detail above, according to the method and apparatus for manufacturing an optical information recording medium of the present invention,
It is possible to manufacture an optical information recording medium in which the difference in the thickness of the thin film layer due to the radial position is small and the reflectance and the recording sensitivity are uniform.

[Brief description of the drawings]

FIG. 1 is a diagram showing an arrangement of a film forming chamber in one embodiment of a manufacturing apparatus of the present invention.

FIG. 2 is a cross-sectional view of a main part of a film forming chamber in one embodiment of the manufacturing apparatus of the present invention.

FIG. 3 is a cross-sectional view showing one embodiment of an optical information recording medium obtained by the manufacturing method of the present invention.

FIG. 4 is a diagram showing the relationship between the radial position of the optical information recording medium manufactured by the manufacturing method of the present invention and the thickness of the lower dielectric layer.

FIG. 5 is a diagram showing a relationship between a radial position of an optical information recording medium manufactured by a conventional manufacturing method and a film thickness of a lower dielectric layer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate loading room 2 Lower dielectric layer first film forming room 3 Lower dielectric layer second film forming room 4 Recording layer film forming room 5 Upper dielectric layer film forming room 6 Reflective layer film forming room 7 Substrate discharge room 10 Controller DESCRIPTION OF SYMBOLS 11 Cathode 12 Cooling channel 13 Magnet 14 Sputtering target 15 Substrate holder 16, 21 Substrate 22 Lower dielectric layer 23 Recording layer 24 Upper dielectric layer 25 Reflective layer 26 Adhesive layer 27 Protective layer

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Nishiuchi 1006 Kazuma Kadoma, Osaka Pref. Matsushita Electric Industrial Co., Ltd. F term (reference) 5D121 AA01 AA03 AA04 AA05 EE03 EE09 EE13 EE14 EE16 EE19 EE27

Claims (6)

[Claims] 1. A method for manufacturing an optical information recording medium comprising a transparent substrate and a multilayer film including a recording layer capable of causing a state change that can be optically detected by irradiation of a light beam, the method comprising: At least one layer included in the above is formed by laminating two or more thin films having different film thickness distributions. 2. A thin film having two or more thin films having different thickness distributions is subjected to magnetron sputtering using two or more cathodes different from each other in at least one selected from a magnetic field distribution on the target, a size of the target, and a consumption amount of the target. The method for manufacturing an optical information recording medium according to claim 1, wherein the medium is formed. 3. The multilayer film includes a dielectric layer in contact with the recording layer, and at least one of the dielectric layers is formed by laminating two or more thin films having different thickness distributions.
Or the method for producing an optical information recording medium according to item 2. 4. The optical information recording according to claim 1, wherein a layer having a thickness of λ / (6.4n) or more is formed by laminating two or more thin films having different thickness distributions. The method of manufacturing the medium. Where λ is the wavelength of the light beam and n
Is the refractive index of the thin film at the wavelength λ. 5. An apparatus for manufacturing an optical information recording medium, comprising a transparent substrate and a multilayer film including a recording layer capable of causing a state change that can be detected optically by irradiation of a light beam. Are formed continuously, and two or more adjacent film forming chambers have at least one selected from a magnetic field distribution on a target, a target size, and a consumption amount of the target. An apparatus for manufacturing an optical information recording medium, comprising different cathodes. 6. The apparatus for manufacturing an optical information recording medium according to claim 5, wherein two or more adjacent film forming chambers include a target made of the same material.