JPH01192028A - Optical recording medium and production thereof - Google Patents

Abstract

PURPOSE:To extend the life of the recording medium and to improve the sensitivity thereof by providing optical recording films of a Te-C-H system formed by a specific method on a substrate and decreasing the content of the Te in the direction parting from the substrate surface. CONSTITUTION:Such recording films 12a, 12b of the Te-C-H system in which the content of the Te decreases in the direction parting from the substrate 11 are provided on the substrate 11. The substrate 11 consists of amorphous polyolefin. The films 12a, 12b are formed by using the Te as a target and by a sputtering method in a gaseous mixture mixed with gaseous argon and gaseous hydrocarbon at 8:2 ratio. The content of the He is made lower in the film 12b than in the film 12a. The concn. of the carbonizing gas is set higher in a late period than at the start of the film formation and thereafter, the films 12a, 12b formed on the substrate 11 are heat-treated for >=5sec at 70-300 deg.C. The optical recording medium 10 having the excellent oxidation resistance, long life and high sensitivity is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an optical recording medium, and more particularly, to a method for manufacturing an optical recording medium having excellent oxidation resistance.

There are two types of optical recording media: one in which physically changed parts such as holes or recesses are formed in a part of the recording film by irradiation with an energy beam, and the other in which a part of the recording film is optically changed. There is also a method of forming an optical property changing section whose optical properties (refractive index, reflectance, etc.) are changed.

As a recording film for any type of optical recording medium, a S film containing tellurium (Te) as a main component has been known (Japanese Unexamined Patent Publication No. 58-71195, JP-A No. 58-9).
No. 234), a recording film containing Te as a main component can form desired physical change parts or optical property change parts (hereinafter collectively referred to as r-pits) with very low energy, and has high sensitivity. It is extremely promising as a material. Sensitivity here refers to the energy required to form pits per unit area (II
J/a&).

However, if Te is left in the atmosphere, it will be oxidized by oxygen or moisture, increasing its light transmittance and becoming transparent.When such Te is used as a recording film, the film thickness is several hundred V. Because the film is very thin and the light transmittance increases due to oxidation of the film, the sensitivity decreases significantly.In other words, when the film is oxidized, the melting and evaporation temperature increases, and the transparency increases the absorption of energy such as light. For example, if a Te film is left in an atmosphere with a temperature of 70°C and a relative humidity of 85%,
Sensitivity decreases by about 20% in about 5 hours, and about 50% in about 15 hours.
% decrease.

In order to solve these problems, various measures have been taken to prevent oxidation of the Te film. One known method is to coat the Te film with a stable inorganic substance. Although this method is effective in preventing oxidation of the Te film,
It has not been put into practical use because it reduces sensitivity and is expensive.

On the other hand, a method of coating TeWA with plastic is also known, but this method is advantageous because the degree of deterioration of sensitivity is small due to the low thermal conductivity of plastic, but it is advantageous because it allows oxygen and water to permeate relatively easily. , is not very useful in preventing oxidation of the Te film.

In addition, in order to solve the above problems,
No. 33320 discloses a method comprising a substrate and a recording film formed on the substrate containing Te as a main component and carbon and hydrogen, and in which the carbon content in the recording film is kept at 5 to 40 atomic %. An optical recording medium is described. Konoyo Una T
e-C-H optical recording media have superior oxidation resistance compared to optical recording media made only of Te.
It is desired to further improve the oxidation resistance of -C-H based optical recording media.

The present invention aims to solve the problems associated with the prior art as described above, and provides an optical recording medium with improved oxidation resistance, long life, and high sensitivity. The purpose of this invention is to provide a manufacturing method for the same.

1 匪ゑ11 The optical recording medium according to the present invention has a Te-C-
It is characterized by being provided with an H-based recording film.

A method of manufacturing an optical recording medium in which a Te-C-H optical recording film is provided on a first substrate in which the Te content decreases in the direction away from the substrate surface according to the present invention includes: When forming a Te-C-H optical recording film in an atmosphere containing hydrocarbon gas, carbonization in the atmosphere occurs at a later stage of film formation than at the start of film formation of the Te-C-H optical recording film. It is characterized by forming a film with a high concentration of hydrogen gas.

A method of manufacturing an optical recording medium in which a Te-C-H optical recording film is provided on a second substrate in which the Te content decreases in the direction away from the substrate surface according to the present invention includes: When forming a Te-C-H optical recording film in an atmosphere containing hydrocarbon gas, carbonization in the atmosphere occurs at a later stage of film formation than at the start of film formation of the Te-C-H optical recording film. It is characterized by forming a film with a high hydrogen gas concentration, and then heat-treating the recording film formed on the substrate at a temperature of 70 to 300° C. for 5 seconds or more.

1 size A1 three-dimensional plate 3 The method for manufacturing an optical recording medium according to the present invention will be specifically described below.

In the present invention, as shown in FIG.
is a substrate 11 and a Te-C- film formed on this substrate 11.
It is composed of an H-based optical recording film 12.

In this Te-C-H optical recording film 12, the Te content decreases in the direction away from the substrate surface. In other words, in the optical recording film 12, the Te content continuously decreases in the direction away from the substrate surface. Alternatively, as shown in FIG. 2, the first optical recording film 12a with a high Te content and the T
The second optical recording I112b whose e content is smaller than that of the first optical recording Ill2a may be gradually reduced in the direction away from the substrate surface, such that the second optical recording I112b is laminated.

As the substrate 11 used in the present invention, in addition to inorganic materials such as glass and aluminum, examples include polymethyl methacrylate, polycarbonate, a polymer alloy of polycarbonate and polystyrene, and U.S. Pat. No. 4,614,778.
Amorphous polyolefin, poly4-methyl-1-pentene, epoxy resin, polyethersulfone, polysulfone, polyetherimide, as shown in the specification
Organic materials such as ethylene/tetracyclododecene copolymers can be used. The thickness of this substrate 11 is preferably 0.5 to 2.5 mm, particularly preferably 1.0 to 1.5 mm.
It is about ++m.

In the present invention, a TO-C-
To form the H-based optical recording film 12, a vacuum evaporation method, a sputtering method, an electron beam evaporation method, or the like can be adopted using TO as a target. 1 g of Ta-C-H optical recording on the substrate 11. The concentration of hydrocarbon gas in the atmosphere is higher in the latter stage of film formation than at the start of film formation in No. 12. Note that when Te is deposited on a substrate in an atmosphere containing hydrocarbon gas, the T
It is conventionally known that a film having a composition of e-C-H can be obtained.

More specifically, the Te-C-H optical recording film 12 is placed on the substrate 1.
When forming a film on 1, the hydrocarbon concentration within the vapor deposition apparatus may be increased continuously or may be increased stepwise.

Continuously increasing the hydrocarbon concentration in the vapor deposition apparatus, the substrate 11
If a Te-C-H optical recording film 12 is formed on the substrate 1
1, the Te content is lower in the direction from the substrate, and therefore the content of C and H is increased.
A -C-H optical recording film 12 is formed. Further, when the hydrocarbon gas concentration in the vapor deposition apparatus is increased stepwise, as shown in FIG. , T
The second optical recording film 12b, which has a low e content and therefore a high C and H content, is formed in this order.

FIG. 3 shows an example of the hydrocarbon gas concentration in the vapor deposition apparatus when forming a Te-C-H optical recording film on the substrate 11. In other words, (a) in FIG. 3 shows the hydrocarbon gas concentration. (b) is a case in which the concentration of hydrocarbon gas is increased continuously, and (C) is a case in which the concentration of hydrocarbon gas is continuously increased and carbonization occurs slightly after film formation. This is a case where the hydrogen gas concentration decreases. As in the case shown in (C), an optical recording film exhibiting excellent oxidation resistance can be obtained even if the hydrocarbon gas concentration is slightly lowered at the very end of film formation.

Hydrocarbons introduced into the vapor deposition apparatus when forming a Te-C-H optical recording film in the present invention include methane, ethane,
Acetylene etc. are used. Such hydrocarbons are
It is usually introduced into the vapor deposition apparatus together with an inert gas, but
Inert gases used at this time include helium, neon, argon, krypton, nitrogen, etc.
Among these, argon is particularly preferred.

In addition to the above-mentioned components, the Te-C-H optical recording film formed in the present invention contains Bi, Zn, Cd, In, and S.
It can also contain low melting point metals such as B, Pb, Sn in amounts up to 25 at.%. Also, Ti, ・Mn, N
At least one selected from the group consisting of i, Zr, Nb, Ta, Pt and Sl! It can also contain up to 25 atom % of metal a. Such metal is Te
An alloy target of Te and this metal may be used as a target to be included in the -C-H based optical recording film.
Alternatively, Te and this metal may be used as separate targets.

The total film thickness of such optical recording film 12 is 100 to 1
μmIE is preferably about 150 to 1,000 people, more preferably about 150 to 400 people.

When the recording film 12 according to the present invention is irradiated with an energy beam such as a laser beam that is modulated (on/off) depending on the information to be recorded, pits are formed in the irradiated area. . This bit may be a physically changed part such as a hole or a recess, or it may be an optical property changed part that changes optical properties such as refractive index or reflectance.

As described above, a Te-C-H optical recording film is formed on the substrate 11, and the concentration of hydrocarbon gas in the atmosphere is lowered in the later stage of film formation than at the start of film formation of the Te-C-H optical recording film. When the film is formed at a higher concentration, the oxidation resistance of the resulting optical recording film is significantly improved. In particular, pitting corrosion, which is thought to occur mainly from the surface of the optical recording medium, is effectively prevented. For example, first, in an atmosphere with an argon/methane ratio of 8/2, T is deposited on a substrate by reactive sputtering using Te as a target.
E content 75 at%, C content 16 at%, H content 9
A first optical recording film of Te-C-H system having a concentration of 59 at.% and a C content of 21 at. %,H
When an optical recording film is manufactured by forming a Tc-C-H-based second optical recording film having a content of 20 at%, this optical recording film is heated to 70°C.
, even if left in an atmosphere with relative humidity of 85% for 300 hours,
The number of pitting corrosion that occurs is 0, and the rate of change in light reflectance is only 9%, whereas argon/methane is 8/
Te-C-H was deposited on the substrate by reactive sputtering using TO as a target in an atmosphere of
When the first optical recording film of the system is left in an atmosphere of 70° C. and 85% relative humidity for 300 hours, the number of pitting corrosion that occurs is 30, and the rate of change in light reflectance reaches as much as 10%.

Note that the number of pitting corrosion was counted visually.

Next, after forming the recording film 12 on the substrate 11 in this way, the recording film 12 may be heated with an inert gas or
The heat treatment is preferably carried out in a reducing gas or an inert gas atmosphere containing some oxygen, and the heat treatment temperature is as follows:
It is necessary that the temperature is below the melting point of the low melting point metal contained in the recording film, preferably 70 to 300°C, especially 90 to 15°C.
The temperature range of 0℃ is good, and the heat treatment time is 5 seconds to 100 seconds.
It is preferably 0 minutes, particularly 5 minutes to 100 minutes.

In this way, by heat-treating the recording film 12 after forming the recording film 12 on the substrate 11, the oxidation resistance of the recording film is further improved, and the recording sensitivity of the recording film is improved. For example, the recording film 12 consisting of the first Te-C-H optical recording film and the second Te-C-H optical recording film deposited on the substrate as described above is heated at 100° C. in a nitrogen gas atmosphere. The resulting optical recording film was heated at a temperature of 70°C and a relative humidity of 85°C for 20 minutes.
% atmosphere for 200 hours, the rate of change in light reflectance is only 11%. Here, an improvement in recording sensitivity means that the energy of an energy beam such as a laser beam required for recording per unit area is reduced.

In the optical recording medium according to the present invention, 're-c' is provided on the substrate such that the TO content decreases in the direction away from the substrate surface.
-H-based optical recording film is a projection recording film, and in this method of manufacturing an optical recording medium, a Te-C-H based optical recording film is formed on a substrate in an atmosphere containing hydrocarbon gas. , the T
The e-C-H optical recording film is formed by increasing the concentration of hydrocarbon gas in the atmosphere in the latter stage of film formation than at the start of film formation, and then, if necessary, the recording film formed on the substrate is heated to 70°C. ~30
Since the heat treatment is performed at a temperature of 0° C. for 5 seconds or more, an optical recording medium with excellent oxidation resistance, long life, and high sensitivity can be obtained.

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples.

Targeting TO, a substrate made of amorphous polyolefin with a diameter of 130 nm was heated at 6X 10-3 Tor in a mixed gas of 8:2 of argon gas and methane gas.
A first Te-C-H film having a thickness of 125 mm was formed by sputtering at DC45W under a vacuum of r.

The film composition of this first TO-C-H film was analyzed by ICP emission spectrometry (inductively coupled plasma emission spectrometry) and organic elemental analysis, and it was found to be Te75C16H9.

Next, on this first Te-C-H film, a mixture of argon gas and methane gas was applied at 6×10'Torr
A film thickness of 1 was obtained by sputtering at DC45W under a vacuum of
An optical recording medium was manufactured by depositing a second Te-C-H film by 25 people.

When the film composition of this second Te-C-H film was analyzed by ICP emission spectrometry, it was found to be Te59C21H2o.

The optical recording medium thus obtained was left in an atmosphere of 70° C. and a relative temperature of 85% for 300 hours, and then the rate of change in light reflectance from the initial value was examined.

The number of occurrences of pitting corrosion was also visually checked.

The results are shown in Table 1.

The optical recording medium obtained in Example 1 was heat treated at 100° C. for 20 minutes in a nitrogen atmosphere.

Regarding the optical recording medium treated in this manner, the rate of change in light reflectance and the number of occurrences of pitting corrosion were examined in the same manner as in Example 1.

The results are shown in Table 1.

A substrate made of amorphous polyolefin with a diameter of 130 fl was heated to 6X 10-3 Tor in a mixed gas of 8:2 of argon gas and methane gas, using L school ■ UTO as a target.
A Te--C--H film with a thickness of 250 mm was formed by the suba-tuttering method at DC45 W under a vacuum of r.

The film composition of this Te-C-H film was Te75C16H9.

This Tc-C-H1l! The rate of change in light reflectance and the number of occurrences of pitting corrosion were investigated in the same manner as in Example 1.

The results are shown in Table 1.

The optical recording medium obtained in Comparative Example 1 was heat-treated at 100° C. for 20 minutes in a nitrogen atmosphere.

Regarding the optical recording medium treated in this manner, the rate of change in light reflectance and the number of occurrences of pitting corrosion were examined in the same manner as in Example 1.

The results are shown in Table 1.

i-yu

[Brief explanation of the drawing]

1 and 2 are cross-sectional views of the optical recording medium according to the present invention, and FIG. 3 is a diagram showing the relationship between the hydrocarbon gas concentration and the vapor deposition time in the vapor deposition apparatus. Agent Patent Attorney Shunichi Suzuki Figure 3 Time (1)

Claims (1)

[Scope of Claims] 1. An optical recording medium characterized in that a Te-C-H optical recording film is provided on a substrate, and the Te content decreases in the direction away from the substrate surface. 2. When forming a Te-C-H optical recording film on a substrate in an atmosphere containing hydrocarbon gas, the Te-C-
The H-based optical recording film is formed by increasing the hydrocarbon gas concentration in the atmosphere in the later stage of film formation than at the start of film formation, and the Te content decreases in the direction away from the substrate surface on the substrate. A method of manufacturing an optical recording medium provided with such a Te-C-H optical recording film. 3. When forming a Te-C-H optical recording film on a substrate in an atmosphere containing hydrocarbon gas, the Te-C-
The H-based optical recording film is formed by increasing the concentration of hydrocarbon gas in the atmosphere in the latter stage of film formation than at the start of film formation, and then the recording film formed on the substrate is heated at a temperature of 70 to 300°C for 5 seconds. The Te-C-
A method for manufacturing an optical recording medium provided with an H-based optical recording film.