JPS6323235A - Optical information recording carrier - Google Patents

Abstract

PURPOSE:To obtain a high reflectivity and stable C/N by forming the titled carrier into multi-layered thin film constitution in which a 1st layer is formed of the compsn. essentially consisting of TeOx added with Pd as an additive and having a small x value and a 2nd layer is formed of the compsn. having the large x value as the thin film compsn. CONSTITUTION:The 1st layer 3 of the optical recording film consisting of the suboxide TeOx1 (O<x1<2) of Te and Pd is provided on the front of a resin substrate 2 consisting of a polycarbonate formed with grooves 1 for guiding light and the 2nd layer 4 likewise consisting of the suboxide TeOx2(O<x2<2) of Te and Pd are provided thereon. The resin substrate 2 is joined to the similar resin substrate 2a formed with groove 1a for guiding light and an adhesive agent 5 consisting of a photosetting resin over the entire surface to the form of a disk. The suboxides of Te of the 1st layer and 2nd layer of the optical recording film are so selected that the x values thereof attain x1<x2.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a disc-shaped information recording carrier used in an optical recording/reproducing system.

BACKGROUND OF THE INVENTION Conventionally, this type of information recording layer has been made mainly of a low oxide of Te, Te0x (x cape 1.○, a mixture of Te and Te02), and additives such as Pd, Cu, etc.
There are materials to which Au and the like are added singly or in combination. These thin film formation methods use TeOx and Pd as vapor deposition sources, for example.
A vacuum evaporation method using two types of co-evaporation, Te and P
It is formed by an O2 reactive sputtering method using an alloy or composite target of d.

Problems to be Solved by the Invention The thin film formed by the above-mentioned vacuum evaporation method or sputtering method has a film composition of a mixture of Te, TeO3, and Pd, and can be regarded as a mixture of TeOx and Pd. When a thin film is formed, it is amorphous and has the property of crystallizing when irradiated with laser light or the like, so it is used as an optical recording film that takes advantage of changes in reflectance. In addition, additives such as Pd act as nuclei for crystallization and speed it up, so this thin film is promising as an optical recording film with very little sensitization, which increases sensitivity over time after recording, and is useful for computers. It is also expected to be used for data files, etc.

When forming such an optical recording film, if a vacuum evaporation method is used, it is necessary to replace the evaporation source every time, so there is a limit to mass production. Therefore, there is a demand for production using a sputtering method, which does not require replacement, has better mass productivity, and is advantageous in terms of pit error rate, which is important for data files. According to this method, it is possible to continuously form a number of optical recording films using one alloy or composite target.

Optical recording films made of TeOx (!: Pd) have different film properties depending on the amount of oxygen contained, that is, the X value.The larger the X value, the more weather resistant the film becomes, but the lower the reflectance, the less it will affect the drive. It is characterized by the occurrence of gaps and a low C/N ratio at high recording power.

On the other hand, when the X value is small, the reflectance is high, but the C/N ratio is low at low recording power, and the film is disadvantageous in terms of weather resistance. Therefore, in addition to having good weather resistance, the reflectance is not too low, and C is stable over a wide recording power range.
In order to obtain an optical recording film that can obtain /N, it is necessary to have contradictory film characteristics as an X value. In fact, when using the sputtering method in the production of optical recording films, if continuous sputtering is performed under certain conditions, T
It is inevitable that the film has a uniform composition of eOx and Pd, but there is a problem that the film becomes a low-sensitivity film with poor C/N ratio at low recording power or a film with low reflectance.

The present invention has been made in view of the above points, and has a simple configuration, high reflectance, and stable recording power over a wide range of recording power.
/N, making it possible to obtain a long-life and highly reliable information recording carrier.

Means for Solving the Problems Technical means of the present invention for solving the above problems are as follows:
The composition is mainly composed of TeOx and Pd as an additive.
The purpose is to form a multilayer thin film structure in which the composition with a small X value is the first layer and the composition with a large X value is the second layer.

The method to realize this thin film composition is to use Te and Pd.
There is a sputtering method using O2 reactive using a composite or alloy target, or a multi-sputtering method using O2 reactive using multiple targets of Te and Pd.

For production The effect of this technical means is as follows.

That is, according to the above configuration, the thin film composition of the first layer near the substrate trap is a mixture of TeOx and Pd having a small X value, resulting in a film having a relatively high reflectance.

Furthermore, the thin film composition of the second layer is TeOx and Pd, which have a large X value.
Since the first layer and the second layer have different refractive indexes at the interface, reflection from the interface is newly added. The reflectance of the second layer alone is low, but due to reflection from the first layer and the interface between the first layer and the second layer, overall when only the average composition of the first layer and the second layer is used. It is possible to obtain a reflectance higher than that of .

Further, since the optical recording film is crystallized by laser beam irradiation, the film properties of the optical recording film are close to those of the average composition of the first layer and the second layer.

That is, the film has high sensitivity even at a low recording power for a film with a high reflectance, and a stable C/N can be obtained over a wide range of recording power. Furthermore, the second layer is an oxygen-rich film because the X value of TeOx is larger than that of a film with an average composition, and it is a weather-resistant film that does not deteriorate easily even when moisture is absorbed or permeated through the adhesive layer. It can be said that.

Embodiment Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings. In FIG. 1, a first layer 3 of an optical recording film made of a low oxide of Te, TeOx1 (0<xl<2) and Pd, is formed on the surface of a resin substrate 2 made of polycarbonate in which a groove 1 for light guide is formed. , Similarly, Te low oxide TeOx2(0(
! A second layer 4 of an optical recording film consisting of Pd and Pd is provided. This resin substrate 2 is made of a similar resin substrate 2a in which a groove 1a for light guide is formed and an adhesive 5 made of a photocurable resin.
The entire surface is joined together to form a disk.

Here, the X value of the low oxide of Te in the first layer and the second layer of the optical recording film is selected so that xl<x2, and the film thickness of each layer is 750.

The first layer 3 and 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 sputtering device using a high-frequency magnetron method, in which the device main body 6 is equipped with a pair of electric poles 8 and 9 inside a chamber 7, and a substrate 1o for forming a thin film and a target 11 for sputtering are attached to each of them. It is being A certain amount of sputtering gas 12, for example a mixed gas of Ar and 02, flows into the chamber 7, and the target composition is sputtered by reactive sputtering to form an optical recording film on the substrate.

For example, the structure of the sputtering target is T.
There is a composite target in which a Pd metal piece is placed or embedded in an e target, but there are also targets made of an alloy of Te and Pd at a certain composition ratio, or multiple targets of each of Te and Pd. There is a multi-target.

Regardless of the target configuration, if a mixed gas containing 02 such as Ar + 02 is used as the sputtering gas, the sputtered target composition will react with 02 before adhering to the substrate and form TeOx. I will do it. Therefore, for the formation of the first and second layers of the optical recording film, the sputtering gas used when forming the first layer must be
2.If the flow rate is increased at a given film thickness, the X value will also increase in the formation of the second layer! 1! 2 can be done continuously and easily. If a crystal oscillator is used to monitor the film thickness, the film thickness can be determined non-destructively in-line during production.

FIG. 3 shows the results of compositional analysis in the film thickness direction of the optical recording film, and the contents of Te, O, Pd, and C are shown in at%, respectively. According to this, T at the center of the film thickness
It can be seen that the contents of e and ○ change stepwise, and a two-layer thin film is formed with good responsiveness by adjusting the flow rate of sputtering gas 02.

It was experimentally confirmed that the optical recording film thus formed had signal recording and reproducing characteristics as shown in FIG. Figure 4 shows the C/N ratio for each recording power. This is a comparison of the second layer (curve A). Curve B has a tendency for C/N to decrease significantly at low recording power, and conversely, curve C has a tendency for C/N to decrease at high recording power. On the other hand, it can be seen that the optical recording film according to the present invention (curve A) has characteristics intermediate between curves B and C, and has film characteristics that combine the characteristics of both.

FIG. 5 shows the reflectance of the optical recording film against the X value of TeOx. First layer composition x1, second layer composition!
The reflectance when 2 is configured alone is point B and point 0, and the reflectance of point A of the optical recording film according to the configuration of the present invention is determined only by the average composition x3 of the first layer and the second layer. It is higher than the reflectance point when configured, and rather the composition of the first layer x
1, the reflectance is close to point B. This is probably because the reflectance 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 added to this.

In the structure of the optical recording film of this example, the thickness of the first layer and the second layer are the same, but the overall film thickness is set to the film thickness with the highest C/N of 13oO8 to 1700; It has been confirmed that even if the thickness of the first layer is thinner than this % and ranges from 100 to 100, a sufficient effect of increasing the reflectance can be obtained.

This can be seen from the fact that the reflectance of the optical recording film is closely related to the reflection from the interface between the substrate and the first layer. ,
It was confirmed that the same effect can be obtained even if the composition x2 and film thickness are selected such that the average composition with the second layer is constant.

Further, the optical recording film according to the configuration of this example is 80'c, a
C/% even after 1000 hours under acceleration conditions of
The decrease in N is about 2 dB, and it can be estimated that the product will have a lifespan of 10 years or more under normal usage and storage environments.

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. It has a configuration in which a third layer 13 of a recording film is provided. The film thickness of the third layer 13 is 50 Å to 300 Å, and the composition of the film is 50 Å to 300 Å.
Teax and Pd with the same or similar X value as the layer
is formed from.

Here, polycarbonate is a resin substrate with low moisture absorption and moisture permeability, but compared to glass substrates and the like, it does not completely prevent moisture from passing through from outside the disk. Therefore, it cannot be said that deterioration of the optical recording film due to moisture passing through the resin substrate does not occur. In this embodiment, a third layer of an oxygen-rich film having strong weather resistance is provided on the surface of a resin substrate, and the weather resistance of the structure of the first embodiment is further improved.

In the structure of this embodiment, the second Te-rich film layer is sandwiched between the second and third oxygen-rich films, and if the I value of each TeOx is xl, x2°x3, then xl A compositional relationship such as <x2-x3 is required.

The signal recording and reproducing characteristics are Xl, X2. It exhibits characteristics of TeOx that are close to the average composition of X3, and the addition of the third layer increases the number of interfaces with different refractive indexes, increasing the reflection effect. In other words, even though the third layer is a low reflectance film, if its thickness is as thin as 50A to 5OOA8 degrees, it will increase the reflection at the interface more than lower the overall reflectance. It was experimentally confirmed that the reflectance was higher than that when the reflectance was composed only of the average composition of the first to third layers.

An optical recording film having such a structure can also be easily produced with a composition that changes stepwise by increasing or decreasing the flow rate of 02 in the sputtering gas, as in the case of the first embodiment. Can be done.

In the above embodiments, when forming an optical recording film, 02
A thin film was formed by adjusting the O2 flow rate in the sputtering gas using a reactive sputtering method, but it was confirmed that the same effect could be achieved by increasing or decreasing the high frequency power while keeping the O2 flow rate constant. Strictly speaking, by lowering the high frequency power, the composition of the optical recording film becomes oxygen lynched, and at the same time, the content ratio of Te and Pd decreases (P).
d/Te also tends to decrease, albeit slightly. Therefore, in this case, a film different from the case where the composition of the optical recording film is adjusted by changing the 02 flow rate is produced, but the Pd/Te
It was found that this effect was small because the amount of change was small. In actual manufacturing, the first layer of the optical recording film may be formed with a high radio frequency power to form a Te-rich film, and the second or third layer may be formed with a low radio frequency power to form an oxygen-rich film. 02 The same effect as in the case of adjusting the flow rate was obtained.0 Note that a magnetron system using high frequency oscillation was used as the sputtering apparatus in this example, but if the cathode was not an insulator, a DC power source could be used. A sputtering method is also possible, and there is no problem in forming the optical recording film of this example.

Effects of the Invention The present invention provides a method for forming an optical recording film containing TeOx, a low oxide of Te, as a main component and using Pd as an additive.
By forming a multilayer film consisting of at least two layers, combining a film with a small value and a film with a large value, it is possible to realize an information recording carrier with high reflectance, high sensitivity even at low recording power, and strong weather resistance.

In addition, in reactive sputtering or the like, an optical recording film can be easily formed by adjusting the O2 flow rate and high frequency power, and it has a great effect in improving mass productivity.

[Brief explanation of drawings]

FIG. 1 is a sectional front view of an optical information recording carrier according to a first embodiment of the present invention, FIG. 2 is a principle diagram of an apparatus showing a manufacturing method of the same embodiment, and FIG. 3 is an optical recording medium according to the same embodiment. Figure 4 is a diagram showing the recording and reproducing characteristics of the same recording film; Figure 6 is a correlation diagram between the composition and reflectance of the same recording film; Figure 6 is a diagram showing the relationship between the composition and reflectance of the same recording film; FIG. 2 is a sectional front view of an optical information recording carrier. 1.1a...Groove for light guide, 2,2a...
-Resin substrate, 3...First layer of optical recording film, 4...
...Second layer of optical recording film, 6...Adhesive, 1
1... sputtering target, 12...
... Sputtering gas, 13... Third layer of optical recording film. Name of agent: Patent attorney Toshio Nakao and 1 other person Condolences 1
Figure 2 Figure 3 Figure 4 Flux power (mW) Figure 5 χ value Figure 6

Claims (6)

[Claims] (1) Te low oxide TeO_x(0
<x<2), the x value is x
The first layer TeO_x__1 and the second layer T where_1<x_2
An optical information recording carrier in which an optical recording film is formed by sequentially laminating eO_x__2. (2) Te low oxide TeO_x(0
<x<2), the x value is x
third layer TeO_x__3, where _1<x_2≒x_3;
An optical information recording carrier in which an optical recording film is formed by sequentially laminating a first layer TeO_x__1 and a second layer TeO_x__2. (3) The optical recording film is a low oxide TeO_x (0<x<
2) The optical information recording carrier according to claim 1, which is a thin film containing Pd as a main component and Pd as an additive. (4) The optical information recording carrier according to claim 1 or 3, wherein the first layer of the optical recording film is formed to have a thickness of 100 Å to 800 Å. (5) The optical information recording carrier according to claim 1 or 3, wherein the third layer of the optical recording film is formed to have a thickness of 50 Å to 300 Å. (6) The optical recording film is a low oxide of Te TeO_x (0<x<
2) The optical information recording carrier according to claim 2, which is a thin film containing Pd as a main component and Pd as an additive.