JPH04222940A - Optical information recording medium and its production - Google Patents

Abstract

PURPOSE:To offer an optical information recording medium having long-term high reliability and to offer the production method of the medium by providing a moisture preventive film with good adhesion to suppress the deformation of a substrate due to moisture absorption. CONSTITUTION:On one surface of a substrate opposite to the recording layer side, there is provided a moisture preventive film comprising an inorg. material formed by sputtering. The present invention features in that the moisture preventive film comprising a mixture of plasma polymers and inorg. material produced by sputtering is formed on a plastic substrate by supplying the source material for plasma polymn. to a film forming chamber where the plastic substrate is disposed, starting discharge and then gradually decreasing the supply amt. of the source material for plasma polymn. while starting to supply a gas for sputtering, and finally, supplying only the gas for sputtering.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording medium and a method for manufacturing the same.

0002

2. Description of the Related Art In the case of an optical information recording medium whose substrate is made of plastic, deformation of the optical information recording medium and deterioration of magnetic properties due to moisture absorption of the substrate becomes a problem.

Therefore, the recording layer of the substrate is made of, for example, Si3N.
Sandwiched with a protective film consisting of 4 components to prevent moisture,
Furthermore, attempts have been made to form a moisture-impermeable inorganic film on the surface opposite to the recording layer to make the amount of moisture absorbed uniform on both sides of the substrate and prevent warping. 58-32238).

However, although a short-term moisture-proofing effect was observed in this attempt, if left for a long period of time under high temperature and high humidity,
Moisture enters from the end faces of the inorganic film and the recording layer, causing peeling of the inorganic film. Furthermore, due to the stress existing in the inorganic film and the difference in coefficient of thermal expansion between the inorganic film and other layers, the inorganic film may peel off or cracks may occur in the inorganic film. Therefore, in the long term, this technology does not solve the problem of deformation of optical information recording media and deterioration of magnetic properties.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical information recording medium that has good adhesion of a moisture-proof film and has high long-term reliability in which deformation of the substrate due to moisture absorption is suppressed, and a method for manufacturing the same. With the goal.

[0006]

[Means for Solving the Problems] A first aspect of the present invention for solving the above problems is an optical information recording medium having a recording layer made of an amorphous magnetic material on a plastic substrate, in which the recording layer is On the side of the substrate opposite to the side where it is formed,
An optical information recording medium characterized by having a moisture-proof film made of a plasma polymerized film and a sputtered film.

Furthermore, the second gist of the present invention is to supply a raw material for plasma polymerization to a film forming chamber in which a plastic substrate is placed, to start electric discharge, and then to gradually reduce the amount of raw material supplied for plasma polymerization. At the same time, supply of sputtering gas is started, and finally only sputtering gas is supplied to coat the surface of the plastic substrate where the recording layer will be formed with a moisture-proof film consisting of a plasma polymerized film and a sputtered film. exists in a method of manufacturing an optical information recording medium characterized in that the method is formed on the opposite surface.

Embodiments of the present invention will be explained in detail below by component.

(Layer structure) In the present invention, a recording layer is provided on a plastic substrate, and a moisture-proof film is provided on the surface of the substrate opposite to the surface on which the recording layer is formed.

However, as shown in FIG. 1, a dielectric layer 11 may be interposed between the plastic substrate 10 and the recording layer 12, and a dielectric layer 11 may be interposed between the plastic substrate 10 and the recording layer 12. , the protective layer 13, and further on the protective layer 13, an ultraviolet curing resin layer 15 may be formed. Also, for example, Al
It is also possible to have a layered structure in which a reflective layer is added.

In this case, the materials of the dielectric layer 11 and the protective layer 13 include, for example, Si, Al, Mg, Ca, Ti,
Compounds (eg, nitrides, oxides) of Zr, Zn, etc. can be used. Note that the thickness of the dielectric layer is 50 to 3
00 nm is preferable, and the thickness of the protective layer is 50 to 300 nm.
m is preferred.

(Substrate) The substrate 10 in the present invention is a substrate made of plastic, and the plastic is not particularly limited as long as it has translucency, and examples thereof include polycarbonate, polymethyl methacrylate, polysulfone, and amorphous polyolefin. , epoxy resin, etc. are preferably used.

(Recording layer) The recording layer 12 in the present invention is:
Made of amorphous magnetic material. Materials for amorphous magnetic materials include:
For example, GaFe, TbFe, TbCo, TbFeCo
, GdTbFe, TbDyFe, GdFe, GdCo,
GdFeCo, TbFeO3, GdIG, etc. are preferably used.

[0014] The thickness of the recording layer is 30 to 300 nm.
is preferable, and examples of methods for forming it include, but are not limited to, vacuum evaporation, sputtering, and the like.

(Moisture-proof film) In the present invention, a moisture-proof film 14 is formed on the surface of the plastic substrate 10 opposite to the surface on which the recording layer 12 is formed. This moisture-proof film consists of a plasma polymerized film and a sputtered film. The thickness of this film is preferably 50 to 300 nm.

[Plasma polymerized film] When a gas of an organic compound is introduced into a film forming chamber where a glow discharge is occurring, the gas collides with the electrons generated as a result of the discharge, resulting in chemically unstable radicals and ions. active species are generated. This active species promotes polymerization. This type of polymerization is called plasma polymerization. A film formed by such polymerization is called a plasma polymerized film. In the present invention, the organic monomer forming the plasma polymerized film is not particularly limited and a wide range of organic compounds can be used, but for example, the following compounds are suitable.

- As organosilicon compounds, vinyltrichlorosilane, tetraethoxysilane, vinyltriethoxysilane, tetravinylsilane, vinyltriacetoxysilane, hexamethyldisilazane, tetramethylsilane, vinyldimethylethoxysilane, trimethoxyvinylsilane, trimethoxy Methylsilane, diethoxydiphenylsilane, diphenylethoxymethylsilane, octyltriethoxysilane, diethyldiphenylsilane, diphenylmethylvinylsilane, tetrabutylsilane, tetrabutoxysilane, tributylvinylsilane, dimethoxydiphenylsilane, dimethylphenylsilane, hexapropyldisiloxane, hexaethyldisiloxane,
Examples include hexamethyldisiloxane.

- Examples of fluorine-based organic compounds include 6-fluorinated propylene, tetrafluoroethylene, monofluoromethane, difluoromethane, trifluoromethane, tetrafluoromethane, tetrafluoroethane, and monofluoropropane.

- Hydrocarbon organic compounds include methane,
Examples include ethane, propane, butane, ethylene, propylene, butene, butadiene, acetylene, propyne, butyne, and the like.

Other examples include vinyl chloride, vinylidene chloride, acrylonitrile, acrylic acid, methyl methacrylate, and styrene.

[Sputtered Film] Sputtering is a phenomenon in which ions generated as a result of electric discharge knock out atoms from a target. The ejected atoms arrive at the substrate and form a thin film. The film formed in this way is called a sputtered film.

In the present invention, materials constituting the sputtered film include, for example, Si, Al, Mg, Ca, Ti,
Examples include inorganic compounds such as Zr and Zn. More specifically, examples include nitrides or oxides of one or more of Si, Al, Mg, Ca, Ti, Zr, Zn, and the like. Of course, it is not limited to nitrides or oxides.

Target materials for forming sputtered films include Si, Al, Mg, Ca, Ti, Zr, and Zn.
For example, a gas such as Ar, N2, O2, etc. may be used as the gas for sputtering. Note that when N2 and O2 are used, nitrides or oxides can be easily generated by reactive sputtering even if single targets such as Si, Al, Mg, Ca, Ti, Zr, and Zn are used. .

[Composition] The mixing ratio of the plasma polymerized film and the sputtered film is not particularly limited, but the substrate side is composed only of the plasma polymerized film, and the surface side of the moisture-proof film is composed only of the sputtered film, and in between, It is preferable to continuously change the mixing ratio. Note that the composition that changes in this way is referred to herein as a gradient composition.

(Example of manufacturing method) FIG. 4 shows an example of an apparatus for forming a moisture-proof film having a gradient composition of a plasma polymerized film and a sputtered film on the substrate surface opposite to the surface on which the recording layer is formed. It is shown in

In FIG. 4, reference numeral 111 is a bell jar constituting a film forming chamber, and a line for introducing raw material monomer 121 and sputtering gas 122 into the bell jar 111 is provided through a mixer 119. ing.

A plastic substrate 116 is placed on the electrode 114, and a target 115, which is integrally attached to the counter electrode 113, is placed opposite the plastic substrate 116.

A moisture-proof film can be formed on a plastic substrate using such an apparatus as follows.

Inside the bell jar 111, the oil diffusion pump 11
7. Operate the oil rotary pump 118 to exhaust the air to about 10-5 Torr, and then supply raw material gas for plasma polymerization at a predetermined flow rate via the mixer 119 to bring the inside of the bell jar 111 to a pressure in the range of 10 to 10-4 Torr. The plasma generation power source 112 is turned on to start discharging. Polymerization occurs with the start of discharge, forming a plasma film. Next, the flow rate of the source gas for plasma polymerization is gradually reduced and the supply of gas for sputtering is started, thereby forming a moisture-proof film consisting of a plasma polymerized film and a sputtered film. Note that, in the end, if only the sputtering gas is used, a moisture-proof film having a gradient composition of the plasma polymerized film and the sputtered film is formed on the plastic substrate 116.

[0030] As the plasma generation power source, any of a high frequency power source, a microwave power source, a direct current power source, an alternating current power source, etc. can be used. Further, the plasma polymerized film portion can also be formed by afterglow discharge polymerization using an external discharge electrode.

As described above, a moisture-proof film having a gradient composition is formed on the surface opposite to the surface on which the recording layer is formed,
Next, by sequentially forming a dielectric film, a recording film, and a protective film on the back surface, an optical information recording medium having the structure shown in FIG. 1 can be obtained.

[0032]

[Operation] In the present invention, since a moisture-proof film made of a plasma polymerized film and a sputtered film is provided on the surface of the substrate opposite to the surface on which the recording layer is formed, deformation of the substrate is prevented over a long period of time. It becomes possible to obtain an optical information recording medium with low reliability and high reliability.

[0033]

[Examples] Examples of the present invention will be described below along with comparative examples.

(Example) In this example, the optical information recording medium 1 having the structure shown in FIG. 1 was manufactured using the apparatus shown in FIG.

A polycarbonate substrate 10 with a diameter of 130 mm and a thickness of 1.2 mm was set in the apparatus shown in FIG. A film 14a having a composition gradient of that of the sputtered film was formed as the moisture-proof film 14 on the surface opposite to the recording layer 12. Note that the total thickness of the moisture-proof film 14 is 12
It was set to 0 nm.

At that time, trimethoxyvinylsilane was used as a raw material monomer for the plasma polymerized film, Ar was used as a sputtering gas, and Si3N4 was used as a target.

[0037]

[0038] A film having a gradient composition between the plasma polymerized film and the sputtered film was confirmed by IR (infrared absorption spectrum). The confirmation is shown in Table 1, No. 1, No
．． 5, No. A film was formed on a KBr substrate under a single condition of No. 8, and the film was measured by transmission. The measurement results are shown in FIG. The lower the ratio of plasma polymerized film (No.
．． 1→No. 8) It can be seen that the transmittance decreases.

Si3N is deposited as a dielectric layer 11 on the surface of the substrate 10 opposite to the moisture-proof film 14 formed under the above conditions.
4, TbFeCo as the recording layer 12, and Si3N4 as the protective layer 13 on the recording layer 12 were sequentially laminated to a thickness of 100 nm by sputtering.

The sputtering conditions were as follows.

[0041] Operating pressure: 10-2 Torr
rHigh frequency power 300W Frequency 13.56MHz Gas
Ar

[0042] Thereafter, an ultraviolet curable resin (manufactured by Dainippon Ink Chemical Co., Ltd., trade name: SD-304) was applied to the outermost surface to a thickness of 12 μm using a spin coating method.
A magneto-optical information recording medium 1 having the structure shown in FIG. 1 was prepared by irradiating the film with ultraviolet light for 30 seconds to crosslink and cure the resin, and then forming a cured ultraviolet resin layer 15 as a top coat.

(Comparative Example 1) In this example, an optical information recording medium 1 having the structure shown in FIG. 2 was manufactured.

In this example, the same substrate 10 as in the example was used. Condition No. of the example was applied to the surface of the substrate 10 opposite to the recording layer 11. 1 was carried out for 5 minutes to form the plasma polymerized film 14b, and then, after sufficient exhaust, the condition No. 1 was carried out for 5 minutes. 9 for 7 minutes to form a sputtered film 14b, thereby forming the moisture-proof film 14. Thereafter, in the same manner as in the example, a dielectric layer 11, a recording layer 12, a protective layer 13, and an ultraviolet resin hardening layer 15 were formed on the recording surface side, thereby producing an optical information recording medium 1 having the structure shown in FIG. 2. That is, in this example, the moisture-proof film 14 has a structure in which a film made only of the plasma polymerized film 14b and a film made only of the sputtered film 14c are laminated.

(Comparative Example 2) In this example, an optical information recording medium 1 having the structure shown in FIG. 3 was manufactured.

In this example, the same substrate 10 as in the example was used. Condition No. 1 was applied directly to the surface of the substrate 10 opposite to the recording layer 12. A 100 nm sputtered film 14c was formed under the sputtering conditions of 9 to serve as the moisture-proof film 14, and then similarly to the example, a dielectric layer 11, a recording layer 12, a protective layer 13, and an ultraviolet resin hardening layer 15 were formed on the recording surface side. An optical information recording medium 1 having the structure shown in FIG. 3 was manufactured. That is, in this example, the moisture-proof film 14 has a structure in which a single film consisting of only the sputtered film 14c is formed.

3 prepared in Example, Comparative Example 1, and Comparative Example 2
Various types of optical information recording media were subjected to an accelerated deterioration test for 500 hours in an environment with a temperature of 80°C and a humidity of 90%, and then left at room temperature for 48 hours. The amount of warpage of the optical information recording medium due to changes was investigated. In the apparatus shown in FIG. 6, the front surface of a constant temperature and humidity chamber 220 is an optical glass 225, a laser beam 223 is incident on a mirror 222 and an optical information recording medium 221 from the outside, and the reflected light is recorded on a recording paper 224. This method calculates the amount of warpage of the optical information recording medium.

After leaving for 48 hours after the accelerated deterioration test, each optical information recording medium was set in a constant temperature and humidity chamber 200 shown in FIG.
The humidity was changed to 80% for 10 minutes, and the change in the amount of warpage of the optical information recording medium at that time was examined. The results are shown in FIG.

The optical information recording media of Comparative Example 1 (○) and Comparative Example 2 (△) were
In the accelerated deterioration test at 00 hours, minute cracks and peeling occurred in the moisture-proof film, and the moisture-proof performance deteriorated. However, in Example (□), the moisture-proof film was formed with good adhesion, and no warping of the optical information recording medium was observed.

[0050]

[Effects of the Invention] It has become possible to obtain an optical information recording medium with high long-term reliability in which the adhesion of the moisture-proof film is good and the deformation of the substrate due to moisture absorption is suppressed for a long period of time.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structural diagram of an optical information recording medium according to an example.

FIG. 2 is a cross-sectional structural diagram of an optical information recording medium according to Comparative Example 1.

FIG. 3 is a cross-sectional structural diagram of an optical information recording medium according to Comparative Example 2.

FIG. 4 is a conceptual diagram of an example of a film forming apparatus used in the manufacturing method of the present invention.

FIG. 5 is a graph showing an infrared absorption spectrum of a moisture-proof film.

FIG. 6 is an external view of an apparatus for measuring warpage of an optical information recording medium.

FIG. 7 is a graph showing the measurement results of the amount of warpage.

[Explanation of symbols]

1 Optical information recording medium 10 Plastic substrate 11 Dielectric layer 12
Recording layer 13 Protective layer 14 Moisture-proof film
14a Mixed film of plasma polymerized film and sputtered film 14b Plasma polymerized film 14c Sputtered film

Claims (2)

[Claims] Claim 1: In an optical information recording medium having a recording layer made of an amorphous magnetic material on a plastic substrate, a plasma polymerized film and a sputtered film are provided on the surface of the substrate opposite to the surface on which the recording layer is formed. An optical information recording medium characterized by having a moisture-proof film consisting of. 2. A raw material for plasma polymerization is supplied to a film forming chamber in which a plastic substrate is placed, and discharge is started, and then the supply amount of the raw material for plasma polymerization is gradually decreased, and a gas for sputtering is gradually reduced. and finally only the sputtering gas is supplied to form a moisture-proof film consisting of a plasma polymerized film and a sputtered film on the surface of the plastic substrate opposite to the surface on which the recording layer is formed. A method for manufacturing an optical information recording medium, characterized in that: