JPH05334727A - Reflecting film of optical information recording disk - Google Patents

Abstract

PURPOSE:To improve the high temp. and high humidity load characteristics of the reflecting film of an optical information recording medium. CONSTITUTION:This optical information recording medium 10 consists essentially of a discoid substrate 1 molded from a transparent resin, a reflecting film 3 formed on the signal face 1a of the substrate 1 and a protective film 4 laminated on the reflecting film 3 and the reflecting film 3 is made of a thin film of an Al alloy contg. 0.5-5.0% at least one among Si, Ti and Mn.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the composition of a reflective film of an optical information recording disk.

[0002]

2. Description of the Related Art Optical information recording discs such as compact discs and video discs have information signals such as voice information, image information and character information converted into a plurality of pit rows and digitally recorded on their signal surfaces. The digitally recorded information signal can be read using laser light.

FIG. 1 is a sectional view of a part of an optical information recording disk (hereinafter, simply referred to as an optical disk) 10. Reference numeral 1 is a disk-shaped substrate molded from transparent resin, and its substrate 1 A plurality of pits 2 in which information signals are digitized are spirally formed on the signal surface 1a. Further, the side opposite to the signal surface 1a is a reproducing surface 1b formed flat. Three
Is a reflective film formed on the signal surface 1 a, and 4 is a protective film laminated on the reflective film 3. Also, if necessary,
A label film 5 on which a disc identification function of the optical disc 10 such as characters, pictures, figures, and coloring is printed on the protective film 4.
Are stacked.

The optical disk 10 thus constructed is
It is mounted on an optical reproducing device (not shown) and rotated at a predetermined number of revolutions, a laser beam emitted from an optical pickup is made incident from the reproducing surface 1b side to read the pit 2 on the signal surface 1a, and the laser beam is reflected by a reflecting film 3 It is well known that a digital signal such as voice information, image information, character information and the like can be reproduced by reflecting the light in the incident direction.

[0005]

By the way, one of the reliability tests of the optical disk 10 is a high temperature and high humidity load test.

In this high temperature and high humidity load test, the optical disk 10 is left in a high temperature and high humidity test tank adjusted to a predetermined high temperature and high humidity for a predetermined time, and then the optical disk 10 is reproduced to obtain a C1 error rate, The reflectance of the reflection film 3 of the optical disk 10 is measured. The C1 error rate indicates a ratio of erroneous signals in frame units.

The high temperature and high humidity load test of the optical disk 10 will be described in detail below.

A conventional optical disc 10 is mounted at a temperature of 105 ° C.
After leaving it in a high temperature and high humidity test tank adjusted to 100% humidity for 15 hours, the C1 error rate was measured. The measured value before high temperature and high humidity load was 0.298%, which was 1 after the high temperature and high humidity load.
It deteriorated to 5.268%. This worse C1 error rate 15.
268% deviates from the standard (standard value of 3% or less), and it is difficult to satisfactorily reproduce. When observing the surface of the reflective film 3 from the reproducing surface 1b side of the optical disk 10 having the deteriorated C1 error rate with an optical microscope, it is observed that defective portions are scattered everywhere.

The reflection film 3 is formed on the signal surface 1a of the substrate 1 by sputtering with a high purity aluminum having a purity of 99.99% as a target material to a thickness of about 50 nμm. The ESC shows that the high-purity aluminum is locally oxidized to transparent aluminum oxide (Al ₂ O ₃ ) in the high temperature and high humidity load test.
Confirmed by A analysis.

Therefore, since the laser beam emitted from the pickup during reproduction is not reflected by the transparent defect portion of the reflection film 3, the pit 2 on the signal surface 1a cannot be read, and the C1 error rate increases. was there.

[0011]

The present invention has been made to solve the above problems, and is an aluminum alloy containing 0.5 to 5.0% of any one of Si, Ti and Mn elements. The present invention provides a reflection film of an optical information recording medium composed of a thin film.

[0012]

EXAMPLE In the present invention, one of Si, Ti, and Mn elements of 0.5 to 0.5 is added to general high-purity aluminum.
As a result of examination with 5.0% being contained, the reflection film 3 of the optical disk 10 having excellent high temperature and high humidity load characteristics could be found.

Here, the Si content of 0.5 to 5.0% means that Si is an effective element for suppressing oxidation, and it is necessary to contain Si in an amount of 0.5% or more in order to expect an oxidation suppression effect. is there. However, if the content is too much 5.0% or more, the composition of the lump (bulk) used as the target material becomes poor in uniformity, and the processability of the lump (bulk) becomes difficult.
It was limited to 5 to 5.0%.

Furthermore, the fact that Ti is 0.5 to 5.0% means that Ti is an effective element for suppressing oxidation, and it is necessary to contain Ti in an amount of 0.5% or more in order to expect an effect of suppressing oxidation. .. However, since the reflectance of the reflective film 3 is lowered if the content of 5.0% or more is excessive, the content is limited to 0.5 to 5.0%.

Further, the Mn content of 0.5 to 5.0% means that Mn is an effective element for suppressing oxidation, and 0.5% or more is necessary to expect an oxidation suppression effect. ..
However, if the content is more than 5.0%, the composition of the lump (bulk) used as the target material becomes poor in uniformity, and the processability of the lump (bulk) becomes difficult.
Limited to 5.0%. The reasons for these limitations will be described later.

Generally, the reflective film 3 of the optical disk 10 is formed by using a sputtering method which is a vacuum film forming technique.
As the target material, it is already well known that high-purity aluminum is used because of the reflectance characteristics and economical efficiency of the formed thin film. This high-purity aluminum reflective film is easily oxidized, but the oxidation does not always show the same tendency in the thin film and the bulk (bulk),
In the case of bulk, high-purity aluminum produces a dense oxide thin film (Al ₂ O ₃ ) on the surface, and this oxide thin film (Al ₂ O ₃ )
₂ O ₃ ) can prevent the progress of internal oxidation. Also, if high-purity aluminum contains other elements,
In some cases, the fineness of surface oxidation may decrease, or high-purity aluminum and the contained element electrochemically form a local battery to start corrosion. However, it was revealed in Experiment 1 below that corrosion may be accelerated or suppressed depending on the type of contained element.

(Experiment 1) With high purity aluminum, Mg,
Using the following materials containing 1% each of Si, Mn, Ti, and Cu elements as target materials, a reflective film 3 was formed on the signal surface 1a of each substrate 1 by the sputtering method under the same conditions, and further reflected. An optical disk 10 is manufactured by forming a protective film 4 made of an ultraviolet curable resin on the film 3, and a high temperature and high humidity load test (temperature 105 ° C., humidity 100%, 5 to 15 hours) is performed on the optical disk 10. C
1 Error rate and reflectance were measured.

Material 1, high-purity aluminum + Mg Material 2, high-purity aluminum + Si Material 3, high-purity aluminum + Mn Material 4, high-purity aluminum + Ti Material 5, high-purity aluminum + Cu Material 6, high-purity aluminum

[0019]

[Table 1]

[0020]

[Table 2] Table 1 shows the measurement results of the reflectance of the reflective film 3 of the optical disk 10 formed by the sputtering method using the materials 1 to 6 as the target materials after the high temperature and high humidity load test.
Table 2 shows the measurement result of the C1 error rate. As for the individual measurement results, the measured values with the reflectance of 70% or less and the C1 error rate of 3% or more are indicated by x marks, but these measured values are out of the standard.

As is clear from these measurement results, the reflectance of the reflective film 3 of these optical disks 10 does not show a large difference in the materials 1 to 6 after the high temperature and high humidity load test, but the C1 error rate is the material. 3 to 5 are Si and M
It was found that n and Ti are the best.

Experiments were subsequently conducted on the optimum contents of each element of Si, Mn, and Ti with respect to high-purity aluminum.

(Experiment 2) In the same manner as in Experiment 1, 0.1 to 5.0% of Si was added to high-purity aluminum as an additive element.
Using the changed materials below as the target material, the reflective film 3 was formed on each substrate 1 by the sputtering method under the same conditions.
The optical disk 10 is manufactured by forming a film on the signal surface 1a of 1., and further forming a protective film 4 made of an ultraviolet curable resin on the reflective film 3. The optical disk 10 is subjected to a high temperature and high humidity load test under the same conditions as in Experiment 1. Then, the C1 error rate and the reflectance were measured.

Material 7, high-purity aluminum + Si 0.1% Material 8, high-purity aluminum + Si 0.2% Material 9, high-purity aluminum + Si 0.3% Material 10, high-purity aluminum + Si 0.4% Material 11, High-purity aluminum + Si 0.5% Material 12, high-purity aluminum + Si 1.0% Material 13, high-purity aluminum + Si 2.5% Material 14, high-purity aluminum + Si 5.0%

[0025]

[Table 3] Table 3 shows the reflectance and C1 after the high temperature and high humidity load test of the optical disk 10 on which the reflection film 3 formed of materials 7 to 14 is formed.
This is the measurement result of the error rate. As for the individual measurement results, the measured values with the reflectance of 70% or less and the C1 error rate of 3% or more are indicated by x marks, but these measured values are out of the standard. In addition, the measured value that satisfies the standard is indicated by a circle.

As is clear from the measurement results, the reflectance of the reflective film 3 formed of the materials 7 to 14 after the high temperature and high humidity load test was all good, with the reflectance of 70% or more. Further, it was found that the C1 error rate was the best when the addition amount of 0.5 to 5.0%, which is the material 11 to the material 14, was added.

An aluminum alloy containing Si in an amount of 5.0% or more deteriorates the composition uniformity of the lump (bulk) used as a target material for sputtering and makes it difficult to process the lump (bulk). , Si was limited to 0.5 to 5.0%.

(Experiment 3) In the same manner as in Experiment 2, the following materials obtained by adding Mn as an additional element to high-purity aluminum were used as target materials, and the reflection films 3 of Materials 15 to 22 were formed by the same sputtering method. Is formed on the signal surface 1a of each substrate 1, and a protective film 4 made of an ultraviolet curable resin is further formed on the reflective film 3 to manufacture an optical disc 10. The optical disc 10 is subjected to a high temperature and high humidity load test. Then, the C1 error rate and the reflectance were measured.

Material 15, high-purity aluminum + Mn 0.1% Material 16, high-purity aluminum + Mn 0.2% Material 17, high-purity aluminum + Mn 0.3% Material 18, high-purity aluminum + Mn 0.4% Material 19, High-purity aluminum + Mn 0.5% Material 20, high-purity aluminum + Mn 1.0% Material 21, high-purity aluminum + Mn 2.5% Material 22, high-purity aluminum + Mn 5.0%

[0030]

[Table 4] (Table 4) shows the reflectance and C1 after the high-temperature and high-humidity load test of the optical disk 10 on which the reflective film 3 formed of materials 15 to 22 is formed.
This is the measurement result of the error rate. As for the individual measurement results, the measured values with the reflectance of 70% or less and the C1 error rate of 3% or more are indicated by x marks, but these measured values are out of the standard. In addition, the measured value that satisfies the standard is indicated by a circle.

As is clear from the measurement results, the reflectance of the reflective film 3 formed of the materials 15 to 22 after the high temperature and high humidity load test was all good, with the reflectance of 70% or more. The outer ring is Material 19 to Material 22, which is 0.5 to
It was found that the added amount of 5.0% was the best.

An aluminum alloy containing 5.0% or more of Mn has poor composition uniformity of a lump (bulk) used as a target material for sputtering, and also has difficulty in workability of the lump (bulk). , Mn is limited to 0.5 to 5.0%.

(Experiment 4) In the same manner as in Experiment 3, the following materials obtained by adding Ti as an additive element to high-purity aluminum were used as target materials, and the reflection films 3 of Materials 17 to 21 were formed by the same sputtering method. Is formed on the signal surface 1a of each substrate 1, and a protective film 4 made of an ultraviolet curable resin is further formed on the reflective film 3 to manufacture an optical disc 10. The optical disc 10 is subjected to a high temperature and high humidity load test. Then, the outer ring and the reflectance were measured.

Material 23, high-purity aluminum + Ti 0.1% Material 24, high-purity aluminum + Ti 0.2% Material 25, high-purity aluminum + Ti 0.3% Material 26, high-purity aluminum + Ti 0.4% Material 27, High-purity aluminum + Ti 0.5% Material 28, high-purity aluminum + Ti 1.0% Material 29, high-purity aluminum + Ti 2.5% Material 30, high-purity aluminum + Ti 5.0%

[0035]

[Table 5] Table 5 shows the measurement results of the reflectance and the outer peripheral ring after the high temperature and high humidity load test of the optical disk 10 on which the reflective film 3 made of the materials 23 to 30 is formed. Each measurement result has a reflectance of 7
0% or less and C1 error rate 3% or more measured value ×
Although indicated by a mark, these measured values are out of the standard. In addition, the measured value that satisfies the standard is indicated by a circle.

As is clear from the measurement results, the reflectance of the reflective film 3 formed of the materials 15 to 22 after the high temperature and high humidity load test was all good, with a reflectance of 70% or more. Further, it was found that the C1 error rate was the best when the addition amount of 0.5 to 5.0%, which is Material 27 to Material 30, was added.

A reflective film sputtered with an aluminum alloy containing 5.0% or more of Ti as a target material has a laser beam reflectance of 70% or less. Therefore, the addition amount of Ti is 0.5 to 5 Limited to 0.0%.

As described above, the reflective film 3 of the optical disk 10 of the present invention is sputtered using an aluminum alloy containing 0.5 to 5.0% of any one of Si, Ti and Mn elements as a target material. The reflective film 3
By forming the above, it is possible to provide a high quality optical information recording medium having improved high temperature and high humidity load characteristics.

[0039]

As described above, the reflection film of the optical information recording medium of the present invention is composed of an aluminum alloy thin film containing 0.5 to 5.0% of any one of Si, Ti and Mn elements. As a result, it is possible to provide a high quality optical information recording medium with improved high temperature and high humidity load characteristics.

[Brief description of drawings]

FIG. 1 is a sectional view of a part of an optical information recording disk.

[Explanation of symbols]

1 ... Substrate, 1a ... Signal surface, 1b ... Reproduction surface, 2 ... Pit,
3 ... Reflective film, 4 ... Protective film, 5 ... Label film, 10 ... Optical information recording disk

Claims (1)

[Claims] 1. A reflective film for an optical information recording disk comprising an aluminum alloy thin film containing 0.5 to 5.0% of any one of Si, Ti and Mn elements.