JPH0693300B2 - Method of manufacturing optical information recording carrier - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for manufacturing a disc-shaped information recording carrier used for an optical recording / reproducing system.

Conventional Technology Conventionally, TeOx (x≈1.0,
(Mixture of Te and TeO ₂ ) as the main component, and as an additive, for example,
Some include Pd, Cu, Au, etc. alone or in combination.
These thin film forming methods are carried out by using, for example, TeOx and Pd as evaporation sources.
It is formed by a vacuum vapor deposition method by co-evaporation using two types of the above, or a sputtering method by O reactive using an alloy of Te and Pd or a composite target.

Problems to be Solved by the Invention The thin film formed by the vacuum deposition method or the sputtering method described above is composed of a mixture of Te, TeO ₂ , and Pd as a film composition,
It can be regarded as a mixture of Pd. Since it is amorphous at the time of forming a thin film and has a property of being crystallized by irradiation with a laser beam or the like, it is used as an optical recording film utilizing a change in reflectance. In addition, since Pd and the like which are additives serve as nuclei for crystallization and have a role of accelerating the speed, this thin film is promising as an optical recording film with very little sensitization in which the sensitivity increases with the passage of time after recording, and it is suitable for computers. It is also expected to be used as a data file.

When such an optical recording film is formed, if the vacuum vapor deposition method is used, the vapor deposition source needs to be replaced every time, which limits the mass productivity. Therefore, there is a demand for production by a sputtering method which does not require replacement and is more mass-producible, which is advantageous for a bit error rate important for data files. According to this method, it is possible to continuously form many optical recording films with one alloy or composite target.

The optical recording film made of TeOx and Pd has different film characteristics depending on the oxygen content, that is, the x value. The larger the x value, the better the weather resistance of the film, but the lower the reflectivity, and the problem of not being applied to the drive occurs.
There is a feature that N is also low. On the other hand, when the x value is small, the reflectance is high, but the C / N at low recording power is low and the film is also disadvantageous to weather resistance. Therefore, in order to obtain an optical recording film that has good weather resistance, a reflectance that is not too low, and a stable C / N can be obtained over a wide recording power range, it is necessary to combine film characteristics that are contradictory as x values. There must be. In fact, when the sputtering method is used in the production of optical recording films, it is inevitable that the composition of TeOx and Pd will be uniform in the film thickness direction if continuous sputtering is performed under certain conditions. However, there is a problem that the film becomes a poorly sensitive film or a film having a low reflectance.

The present invention has been made in view of the above points, and has a simple structure, high reflectance, and stable in a wide recording power range.
It is intended to provide a method for producing a highly reliable information record carrier having a long C / N and long life.

Means for Solving the Problems The technical means of the present invention for solving the above problems is to use, as a thin film composition, TeOx as a main component and Pd as an additive, but a composition with a small x value is used for the first layer. Thus, a multi-layered thin film structure in which a composition having a large x value is used as the second layer.

As a method of achieving a thin film composition, a sputtering method by O ₂ reactive using a composite or alloy target of Te and Pd, or a multi-sputtering method by O ₂ reactive using a plurality of targets of Te and Pd is used. is there.

Operation The effects of this technical means are as follows.

That is, according to the above configuration, the thin film composition of the first layer close to the substrate is a mixture of TeOx and Pd having a small x value,
The film has a relatively high reflectance. Further, the thin film composition of the second layer is a mixture of TeOx and Pd having a large x value, and since the interfaces of the first layer and the second layer have different refractive indexes, reflection from the interface is newly added. Become. When the second layer alone has a low reflectance, but due to reflection from the first layer and the interface between the first layer and the second layer, only the average composition of the first layer and the second layer is taken as a whole. Higher than the reflectance of

The film characteristics of the optical recording film are close to the film characteristics of the average composition of the first layer and the second layer, because they are crystallized by laser light irradiation. That is, the film characteristics have high sensitivity even with a low recording power in spite of the film having a high reflectance, and a stable C / N can be obtained in a wide range of recording power regions. In addition, the second layer has more TeOx x than the average composition film.
Since the value is large, it can be said that the film is an oxygen-rich film, has little deterioration even with respect to moisture absorption and moisture permeation transmitted through the adhesive layer, and has strong weather resistance.

Example Hereinafter, one example of the present invention will be described with reference to the accompanying drawings. In FIG. 1, a low oxide of Te is formed on the surface of a resin substrate 2 made of polycarbonate in which a groove 1 for light guiding is formed.
First layer 3 of optical recording film composed of TeOx ₁ (O <x ₁ <2) and Pd
Similarly, the second layer 4 of the optical recording film made of Pd and TeOx ₂ (O <x ₂ <2), which is a low oxide of Te, is provided. The resin substrate 2 is entirely bonded to a similar resin substrate 2a having a light guiding groove 1a formed therein by an adhesive 5 made of a photo-curing resin to form a disk. Here, the first layer and the second layer of the optical recording film
The x value of the low oxide of Te in the layer is selected so that x ₁ <x _2, and the film thickness of each layer is 750Å.

The first layer 3 and the second layer 4 of the optical recording film of such a disc
Are formed, for example, by the method shown in FIG.
FIG. 2 shows a high-frequency magnetron type sputtering apparatus, in which the apparatus main body 6 is provided with a pair of electrodes 8 and 9 inside a chamber 7, each of which is provided with a substrate 10 for thin film formation.
And a sputtering target 11 is attached. A certain amount of sputter gas 12, for example, a mixed gas of Ar and O ₂ flows into this chamber 7, and the target composition is sputtered by reactive sputtering to form an optical recording film on the substrate.

As the structure of the sputtering target, for example, Te
There is a composite target in which a metal piece of Pd is placed or embedded in the target of the above. In addition to this, a target made of an alloy of Te and Pd with a constant composition ratio, or a plurality of each target of Te and Pd was used. There are multiple targets.

Regardless of the configuration of any target, as a sputtering gas, for example, Ar that combines an inert gas such as Ar, He, Ne and O ₂
If a mixed gas of + O ₂ is used, the sputtered target composition reacts with O ₂ until it adheres to the substrate, forming TeOx. Therefore, for forming the first layer and the second layer of the optical recording film, if the O ₂ flow rate of the sputtering gas used when forming the first layer is increased to a predetermined thickness, the second layer is formed. Formation can also be performed continuously and easily so that the x value is x ₁ <x ₂ . Here, if a crystal oscillator is used as the film thickness monitor, the film thickness can be known non-destructively in-line even in production.

FIG. 3 shows the results of composition analysis in the film thickness direction of the optical recording film, and the contents of Te, O, Pd, and C are shown in at%. According to this, it is understood that the contents of Te and O are changed stepwise at the center of the film pressure, and the two-layer thin film is formed with good responsiveness by adjusting the flow rate of the sputtering gas O ₂ .

It has been experimentally confirmed that the optical recording film thus formed has a signal recording / reproducing characteristic as shown in FIG. FIG. 4 shows C / N for each recording power. The optical recording film is composed of only the first layer (curve B) and the second layer (curve C), and the first and second layers. It is a comparison of the two layers (curve A). Curve B has a low recording power
C / N tends to have a large fixed price, and curve C, on the contrary, has a low C / N at high recording power. On the other hand, it can be seen that the optical recording film (curve A) according to the constitution of the present invention has intermediate characteristics between the curve B and the curve C, and has film characteristics having both characteristics.

FIG. 5 shows the reflectance of the optical recording film with respect to the x value of TeOx. The reflectances when the composition x ₁ of the first layer and the composition x ₂ of the second layer are respectively configured are points B and C, and the reflectance A of the optical recording film according to the present invention is 1st layer and 2nd
The reflectance is higher than the D point when the layer is composed of only the average composition x ₃ , and is rather a value close to the B point for the first layer composition x ₁ . It is considered that the reflectivity of the optical recording film is greatly influenced by the reflection at the interface between the substrate and the first layer, and the reflection at the interface between the first layer and the second layer is further added.

In the structure of the optical recording film of this embodiment, the first layer and the second layer have the same film thickness, but the total film thickness is 1300Å to 17
The film thickness with the highest C / N of 00Å, and the film thickness of the first layer is 1/2
It was confirmed that the effect of increasing the reflectance is sufficiently obtained even when the thickness is 100 Å to 800 Å. This can be seen from the fact that the reflectivity of the optical recording film greatly contributes to the reflection from the interface between the substrate and the first layer, and the value of the composition x ₁ of the first layer is smaller and the film is thinner. It was confirmed that the same effect can be obtained by selecting the composition x ₂ and the film thickness so that the average composition of the second layer is constant.

Further, the optical recording film according to the structure of the present example shows a decrease in C / N of 2 dB even after 1000 hours under the acceleration condition of 80 ° C. and 80%.
It can be estimated that the life is 10 years or more under normal use and storage conditions.

Next, a second embodiment of the present invention will be described with reference to the drawings. In FIG. 6, the same parts as those in FIG. 1 are designated by the same reference numerals, and a light beam is provided between the resin substrate 2 made of polycarbonate having the light guiding groove 1 and the first layer 3 of the optical recording film. The third layer 13 of the recording film is provided. Third layer 13
Has a film thickness of 50Å to 300Å, and the composition of the film is formed from TeOx and Pd having an x value equal to or close to that of the second layer.

Polycarbonate is a resin substrate having low moisture absorption and moisture permeability, but it is not perfect to prevent moisture from passing from the outside of the disk as compared with a glass substrate or the like. Therefore, it cannot be said that the optical recording film is not deteriorated by the moisture passing through the resin substrate. In this example, a third layer of an oxygen-rich film having high weather resistance is provided on the surface of a resin substrate, and the weather resistance in the configuration of the first example is further improved.

In the structure of the present embodiment, the second layer of the Te-rich film is sandwiched between the second layer of the oxygen-rich film and the third layer, and the x values of the respective TeOx are x ₁ , x ₂ , and x ₃ . Then, a composition relation of x ₁ <x ₂ x ₃ is required. The signal recording / reproducing characteristics are x ₁ , x
_It shows the characteristics of TeOx close to the average composition of ₂ and ₃ and the reflectance is 3rd.
Since the layers are added, the number of interfaces having different refractive indexes is increased, and the effect of reflection is increased. That is, although the third layer is a film having a low reflectance, if the film thickness is as thin as about 50 Å to 300 Å, the reflectance at the interface is increased more than the reflectance is reduced as a whole. It was experimentally confirmed that the reflectance was higher than the reflectance when only the average composition of the first layer to the third layer was used.

Also in the optical recording film having such a structure, the optical recording film whose composition changes stepwise can be easily manufactured by increasing or decreasing the flow rate of O ₂ in the sputtering gas as in the case of the first embodiment. You can

Or In the embodiment, when forming the optical recording layer with a sputtering method using O ₂ reactive, but to form a thin film by controlling the flow rate of O ₂ in the sputtering gas, the same is O ₂ flow rate It was confirmed that this can also be done by increasing or decreasing the high frequency power with a constant value. Strictly speaking, by decreasing the high frequency power, the composition of the optical recording film becomes oxygen-rich, and at the same time, the Te / Pd content ratio Pd / Te tends to decrease slightly. Therefore, in this case, a film different from the case where the composition of the optical recording film is adjusted by changing the O ₂ flow rate is formed, but since the change amount of Pd / Te is small,
It was found that the effect of this was small. In an actual device, the first layer of optical recording has high frequency power and is
A rich film may be formed, and the high frequency power of the second or third layer may be reduced to form an oxygen-rich film, and the same effect as in the case of adjusting the O ₂ flow rate was obtained.

As the sputtering apparatus of the present embodiment, a magnetron method using high frequency oscillation was used, but if the cathode is not an insulator, a sputtering method using a DC power source is also possible. There is no hindrance to the formation.

EFFECTS OF THE INVENTION The present invention is a multi-layer composed of at least two layers in which a film having a small x value and a film having a large x value are combined in the formation of an optical recording film containing TeOx, which is a low oxide of Te, as a main component and Pd as an additive. By forming the film, it is possible to realize an information record carrier having a high reflectance, a high sensitivity even with a low recording power and a strong weather resistance.

Further, in reactive sputtering or the like, the optical recording film can be easily formed by adjusting the O ₂ flow rate and the high frequency power, which has a great effect on improving mass productivity.

[Brief description of drawings]

FIG. 1 is a sectional front view of an optical information recording carrier in a method for manufacturing an optical information recording carrier of the present invention, FIG. 2 is a principle view of an apparatus for carrying out the manufacturing method, and FIG. FIG. 4 is a composition analysis diagram of the recording film, FIG. 4 is a recording / reproducing characteristic diagram of the optical recording film, and FIG. 5 is a correlation diagram of composition and reflectance of the optical recording film.
FIG. 6 is a sectional front view of another optical information record carrier in the manufacturing method of the present invention. 1, 1a ... Optical guide groove, 2, 2a ... Resin substrate, 3 ... First layer of optical recording film, 4 ... Second layer of optical recording film, 5 ... Adhesive,
11 ... Sputtering target, 12 ... Sputtering gas, 13 ... Third layer of optical recording film.

Claims (4)

[Claims] 1. In reactive sputtering of inert gas and oxygen using at least one composite or alloy target composed of Te and Pd, or a multi-target composed of a plurality of single Te and Pd, TeOx and Pd are used. A method for manufacturing an optical information recording carrier, wherein the first layer TeOx ₁ and the second layer TeOx _{2 in} which the x value of the optical recording film is x ₁ <x ₂ are sequentially formed by adjusting the flow rate of oxygen. 2. An x value of an optical recording film made of TeOx and Pd is x ₁ <x ₂
The third layer TeOx ₃ , which becomes x ₃ , the first layer TeOx ₁ , and the second layer TeOx ₂ ,
A method for manufacturing an optical information recording carrier, which is sequentially formed by adjusting a flow rate of oxygen in reactive sputtering of an inert gas and oxygen. 3. The optical information recording carrier according to claim 1, wherein the first layer TeOx ₁ and the second layer TeOx ₂ of the optical recording film are formed by adjusting the power of a high frequency power source output or a DC power source output. Production method. 4. A third layer TeOx ₃ , a first layer TeOx ₁ , and a second layer of an optical recording film.
The method for producing an optical information recording carrier according to claim _{2, wherein} the formation of the layer TeOx ₂ is performed by adjusting the power of the high frequency power source output or the DC power source output.