JP2002129260A - Sputtering target material for thin film deposition and thin film and optical recording medium using the material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alloy material which maintains high reflectance, has enhanced weather resistance, is easily produced as the alloy and has stability and simplicity in a sputtering stage when used as a sputtering target and to provide a thin film and an optical recording medium. SOLUTION: An alloy obtained by incorporating Ag with, by weight, 0.1 to 5.0% Au and containing at least one or more kinds of elements selected from the groups consisting of Cu, Al, Ti, Pd, Ni, V, Ta, W, Mo, Cr, Ru and Mg by 0.1 to 5.0% is used as a sputtering target material for thin film deposition, thereby a thin film composing an optical recording medium 10, i.e., a reflection film 16 is deposited, so that the optical recording medium 10 using the reflection film as a composing element is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target material for forming a thin film, a thin film formed by using the same, and an optical recording medium.

[0002]

2. Description of the Related Art CD (Compact Disc) and DVD (Digita
l Optical disk such as Versatile Disc) or MD (Mi
rewritable optical recording media such as ni-disc) and MO (Magnet Optical Disc) or rewritable optical recording media such as phase-change optical disks, and Al and Al alloys are generally used as the material of the reflective film applied to these optical recording media. Is known.

[0003] When reproducing recorded information in the various optical recording media described above, this Al or Al alloy can provide a reflectance of not less than a certain value in a specific optical wavelength region and has a low heat conduction characteristic. Are better. In addition, it is possible to obtain a stable coating property with respect to the fine uneven grooves formed in the optical recording medium, and furthermore, when the optical recording medium product is obtained, weather resistance to non-metal elements contained in the air. It has the advantage that it has excellent performance and changes in timekeeping are extremely small over a long period of time.

[0004]

However, the reflectance of a thin film formed of Al or an Al alloy is, for example, about 80% for light having a wavelength of 800 nm, and depending on the use of an optical recording medium, It cannot be said that a sufficient reflectance has yet been obtained.

On the other hand, CD-R (Compact Disc-Recordab)
In le), if a reflective film is formed using an Al-based material, a sufficiently high reflectance cannot be obtained.
Application of Au as a material for the reflective film is being studied. However, since Au has a problem of high cost as a material, Ag or Cu is being studied as a substitute material for Au.

However, Ag is chemically active against non-metallic elements such as chlorine, oxygen, sulfur and the like, and has a problem in terms of weather resistance in a special environment such as seawater. ing.

On the other hand, Japanese Patent Application Laid-Open No. 57-186224,
JP-A-7-3363 and JP-A-9-156224 disclose a technique of improving weather resistance by adding a predetermined impurity to Ag.
That is, JP-A-57-186224 discloses that AgC
For the u alloy (Ag content is 40 atomic% or more), JP-A-7-3363 discloses an AgMg alloy (Mg content is 1 to 10 atomic% or more), and JP-A 9-156224 discloses an AgOM alloy. (M is Sb, Pd, Pt) alloy (O content is 10 to 40 atomic%, M content is 0.1 to 10
Atomic%).

However, in these alloy materials, the composition range of the elements forming the alloy is wide, and the relationship between the content of the elements forming the alloy, the weather resistance, and the reflectance when a thin film is formed is not necessarily required. Not explicitly stated. In particular,
Improvement in weather resistance due to addition of a small amount of impurities to Ag has not been sufficiently achieved, and it is often unclear about the reliability as a reflection film when employed in an optical recording medium.

Further, Mg is an alkaline earth metal, and since such an element or ion is chemically unstable, an alloy using the same has a weather resistance to chlorine and the like. There was a need to improve.

In order to solve the above problems, the inventors of the present invention have to maintain high reflectivity as compared with Ag, improve weather resistance, ease of manufacturing when manufacturing an alloy, and have a problem in using as a sputtering target. As a result of intensive studies on various problems of stability and simplicity in the sputtering process, a sputtering target material for forming a thin film capable of solving these problems, a thin film formed by using the sputtering target material, and optical recording The medium was obtained.

[0011]

The sputtering target material for forming a thin film according to the present invention comprises Ag as a main component, and
u of 0.1 wt% or more and 5.0 wt% or less, Cu,
Al, Ti, Pd, Ni, V, Ta, W, Mo, Cr,
Containing at least one element of at least 0.1 wt% and at most 5.0 wt% from the group consisting of Ru and Mg;
It is characterized by being made of a metal material containing at least these elements.

The thin film according to the present invention contains Ag as a main component, contains Au in a range of 0.1 wt% to 5.0 wt%, and contains Cu, Al, Ti, Pd, Ni, V, Ta, W, and M.
It contains at least one element selected from the group consisting of o, Cr, Ru, and Mg in an amount of 0.1 wt% or more and 5.0 wt% or less, and is formed using a metal material containing at least these elements. It is characterized by comprising.

Further, the optical recording medium according to the present invention may be made of Ag
As a main component, containing Au at 0.1 wt% or more and 5.0 wt% or less, and Cu, Al, Ti, Pd, Ni, V, Ta,
At least one element selected from the group consisting of W, Mo, Cr, Ru, and Mg in an amount of 0.1 wt% or more and 5.0 or more;
It is characterized by having a thin film formed by using a metal material containing at least these elements at a content of at most wt%.

According to the present invention, when applied as a sputtering target material for forming a thin film or a thin film for an optical recording medium, hydrogen resistance and oxygen resistance of Ag, chlorine resistance of Au,
Due to the interaction of sulfur resistance, contamination by non-metallic elements, such as chlorine, hydrogen, oxygen, and sulfur, which are considered in the atmosphere or special environments, and in the environment and atmosphere required for use in optical recording media High weather resistance can be improved.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The sputtering target material for forming a thin film according to the embodiment of the present invention contains Ag as a main component, contains Au in a range of 0.1 wt% to 5.0 wt%, and includes Cu, Al, Ti, Pd, Ni, V, Ta, W, M
It contains at least one element selected from the group consisting of o, Cr, Ru, and Mg in an amount of 0.1 wt% or more and 5.0 wt% or less, and is made of a metal material containing at least these elements. .

In the examples described below, a sputtering target material for forming a thin film according to the present invention, a thin film formed using the thin film, and an optical recording medium having the thin film have a disc having a structure having two information recording layers. A case in which the present invention is applied to a disk-shaped optical disk will be described. However, the present invention is not limited to such an optical disk and its shape, but may be a magneto-optical disk, a phase-change disk, or any other optical recording having a metal thin film on an information layer such as a card-like or sheet-like. Applicable to media.

In the optical recording medium manufactured in the following example, as shown in FIG. 1, a first substrate 1 and a second substrate 2 are laminated via, for example, a light-transmitting photo-curable resin 20. The optical recording medium has a two-layer structure.

The first substrate 1 is formed, for example, by injection molding of a light-transmitting resin such as polycarbonate or the like, on one principal surface thereof with first fine irregularities 21 such as data recording pits or pregrooves.
And a translucent film 15 on which the first information recording layer 11 is formed.

Further, similarly to the first substrate 1, the second substrate 2 laminated on the first substrate 1 is formed on one principal surface by injection molding of a light transmitting resin such as polycarbonate. It has second fine irregularities 22 such as recording pits or pregrooves, on which a reflective film 16 formed by using the silver alloy according to the present invention is formed, and the second information recording layer 12 is formed. It has been done. The reflection film 16 made of this silver alloy can be formed by, for example, an RF (AC) magnetron sputtering method.
It is formed to a thickness of about 0 to 150 nm.

Further, on the second information recording layer 12, a protective film 30 made of, for example, an acrylic ultraviolet curable resin is provided.
Is formed.

In the optical recording medium having the two-layer structure shown in FIG. 1, when reproducing the information recorded on the second information recording layer 12, a light beam having a wavelength of 800 nm is irradiated to reproduce the information.
Is focused on the information recording layer 12, and information is reproduced. On the other hand, when reproducing the information recorded on the first information recording layer 11, a light beam having a wavelength of 650 nm is irradiated so that the first information recording layer 11 is focused, and the information is reproduced. To

Hereinafter, the silver alloy according to the present invention and a thin film produced using the same, that is, the reflection film 16 shown in FIG. 1 will be described.

As described above, the present invention is intended to maintain high reflectivity, improve weather resistance, facilitate production of alloys,
In order to solve various problems of stability and simplicity in the sputtering process when used as a sputtering target, Ag is used as a main component, and Au is used in an amount of 0.1.
wt% to 5.0 wt%, Cu, Al, T
i, Pd, Ni, V, Ta, W, Mo, Cr, Ru, M
g containing at least one element selected from the group consisting of g and 0.1 wt% or more and 5.0 wt% or less,
An object of the present invention is to obtain a sputtering target material for forming a thin film made of a metal material containing at least these elements, a thin film formed using the same, and an optical recording medium having the thin film.

Au was selected as the sputtering target material for the silver alloy according to the present invention because it was added to the entire alloy of Au, which is an additive element when the alloy was solidified by cooling during the melting process when the alloy was produced. Segregation can be suppressed. Alternatively, there is an advantage that no intermetallic compound is formed during the step of manufacturing the alloy.

Ag easily bonds with sulfur. If left in the air for a long time, Ag reacts with sulfur at the interface that comes into contact with the air to form silver sulfide (Ag ₂ S), which turns black and deteriorates reflection characteristics. Resulting in. Further, it reacts violently with chlorine to form silver chloride (AgCl), which becomes cloudy and deteriorates reflection characteristics. In addition, the reaction portion with chlorine grows and expands, the clouded portion expands, and the reflection characteristics are further deteriorated, thus impairing the physical characteristics of Ag. However, on the other hand, Ag is a substance that is relatively stable with respect to oxygen and hydrogen, particularly very stable with respect to hydrogen, and has a state of bonding with oxygen after being left for a long time in an oxygen atmosphere. Even if the state of bonding with hydrogen is confirmed after being immersed in water and left to stand, the reactivity with hydrogen is found to be stable. For this reason, it is applied to an additive material for a photosensitive material for the purpose of barrier properties against oxygen and hydrogen, a high melting point brazing material, and the like.

According to the sputtering target material for forming a thin film described above, the interaction between the hydrogen resistance and oxygen resistance of Ag and the chlorine resistance and sulfur resistance of Au causes the interaction between chlorine, hydrogen, oxygen and sulfur in the atmosphere or in a special environment. Thus, it is possible to realize a higher improvement in weather resistance as compared with Ag in an environment or atmosphere required for adoption as an optical recording medium when contamination by a non-metallic element is considered.

In the case where a thin film of an optical recording medium is formed using the above-mentioned sputtering target material for forming a thin film, a practically desirable high reflectance is obtained.
That is, it is confirmed that the optical recording medium has excellent characteristics as a reflective film.

Further, when a sputtering target material for forming a thin film is used as a material for forming a reflection film of an optical recording medium, the weather resistance which is important as a reflection film of an optical recording medium is considered when Ag alone is used. It has been confirmed that it is further improved in comparison.

Next, Ag obtained by adding a predetermined amount of Au to Ag is used.
A thin film for an optical recording medium, that is,
When a reflective film was formed to produce an optical recording medium, the reflectance with respect to laser light of a predetermined wavelength was measured. In this case, a thin film of an optical recording medium, that is, a reflective film is formed using a sputtering target material for forming a thin film of an AgAu alloy in which Ag is contained in an amount of 0.1 to 5.0 atomic% of Ag. An optical recording medium is manufactured and a wavelength of 80
The respective reflectances at the time of irradiating a laser beam of 0, 600, and 400 nm are measured, and the measurement results are shown in Table 1.

[0030]

[Table 1]

According to the measurement results shown in Table 1, Ag was expressed as A
When a thin film of an optical recording medium is formed using a sputtering target material for forming a thin film of an AgAu alloy containing 0.5 to 4.9 atomic% of u, a practically desirable high reflectance can be obtained. I understand. That is,
As shown in Table 1, 0.5 to 5.0 atomic% of Au is contained in Ag.
When a thin film of an optical recording medium is formed by using a contained sputtering target material for forming a thin film of an AgAu alloy, particularly when a laser beam having a wavelength of 800 nm is irradiated, a high reflectance of 88% or more is obtained. It can be seen that the obtained film has excellent characteristics as a reflective film of an optical recording medium.

That is, when a sputtering target material for forming a thin film of an AgAu alloy containing 0.5 to 4.9 atomic% of Au in Ag is used as a material for forming the reflection film of the optical recording medium, Ag is used. Compared with the case of using alone, the reflectance is 4 to 5% at the maximum in the measurement in the same wavelength region.
It can be suppressed to a small degree. Further, with regard to weather resistance, which is important as a reflection film of an optical recording medium, by adding Au, it is possible to further improve the weather resistance as compared with the case where Ag is used alone.

Next, an AgAu alloy containing 1.2% by weight of Au in Ag is added to Cu, Al, Ti, Pd,
Any of Ni, V, Ta, W, Mo, Cr, Ru, and Mg is added in an amount of 0.5 to 0.9% by weight, and AgAuX (X is Cu, Al, Ti, Pd, Ni ,
V, Ta, W, Mo, Cr, Ru, Mg) alloys, forming a reflective film of an optical recording medium with the alloy, and producing an optical recording medium having a reflectance to a laser beam of a predetermined wavelength. It was measured.

In this case, the wavelengths 800, 600, 400n
The reflectivity when each of the m laser beams was irradiated was measured, and the measurement results are shown in Table 2.

[0035]

[Table 2]

As shown in Table 2, Ag contained 1.
In an AgAu alloy containing 2 atomic%, any one of elements such as Cu and Al is added in an amount of 0.5 to 0.9% by weight, respectively.
Au is added to the added AgAuX alloy or Ag.
2% by weight, and further 0.5 to 0.9% by weight of Cu
When a thin film of an optical recording medium is formed using a sputtering target material for forming a thin film of an Ag alloy contained therein, a practically desirable high reflectance is obtained.

That is, as shown in Table 2, when irradiated with a laser beam having a wavelength of 800 nm, the AgAu alloy contains any one of elements such as Cu and Al in an amount of 0.5 to 0.9, respectively. Using a sputtering target material for forming a thin film of an added AgAuX alloy or an Ag alloy containing 1.2% by weight of Au and 0.1 to 2.9% by weight of titanium in Ag. When a thin film of a recording medium is formed, a high reflectance of 88% or more can be obtained, and the optical recording medium has excellent characteristics as a reflection film.

In the above description, the AgAu alloy
Although the case where any one of the elements such as Cu and Al is contained has been described, the present invention is not limited to this example.

Further, in Table 2, the AgAu alloy
Although the case where any one of elements such as Cu and Al is contained has been described, the present invention is not limited to this example, and any one or two or more other elements may be contained. AgAu alloys can also be applied, and even when these are used, high reflectivity was obtained and excellent characteristics as a reflective film of an optical recording medium were obtained.

Next, regarding the sputtering rate when forming a thin film for an optical recording medium, that is, a reflective film using the Ag alloy of the present invention, the sputtering target when forming a reflective film using Ag alone is used. This will be described in comparison with.

As the sputtering conditions, the ultimate pressure was 4 × 10 ⁻³ Pa, the sputtering pressure was 0.76 Pa, the sputtering gas and the atmosphere were Ar atmosphere, and the gas flow rate was 20 sccm.

Table 3 below shows the measurement results of the relationship between the material for forming the thin film, the film forming power, and the film forming time.

[0043]

[Table 3]

As shown in Table 3, when a thin film is formed using the Ag alloy of the present invention, the film formation time increases by about 10 to 50% as compared with the case where Ag is used alone. The film forming time can be remarkably reduced as compared with the etching rate in the case of using Al or Au which can be considered as an alternative material.

Next, a method for producing the sputtering target material of the present invention was examined. Examples of the method for producing the sputtering target material of the present invention include a melting method in an air atmosphere and a melting method in a vacuum. When an Ag alloy is produced by a melting method, first, a base mother alloy is produced, and Ag is additionally added thereto, and the content of the metal contained in the alloy so that Ag becomes a specified amount. Shall be prepared.

The case where the process is performed in the atmosphere will be described. First, in an Ar atmosphere (400 to 600 Torr), Ag
-Au-X (X is Cu, Al, Ti, Pd, Ni,
V, Ta, W, Mo, Cr, Ru, Mg) alloys are melted and mixed by arc melting to prepare a master alloy.

Next, Ag is melted in a high-frequency melting furnace. The amount of Ag at this time is an amount obtained by subtracting the amount of Ag in the master alloy from the total amount of dissolution. The melting temperature at this time is, for example, 1000 to 1300 ° C.
A 1-0.2 liter normal graphite crucible is used.

After being completely melted, an antioxidant is introduced,
Suppresses and prevents solid solution with oxygen during melting. As antioxidants, borax, sodium borate, lithium borate,
Carbon or the like can be used.

In a completely melted state, leave for about 1 hour,
The above mother alloy is added and melted for another 0.5 to 1 hour. The melting temperature at this time is, for example, 1050 to 1400 ° C.
And

Although the dissolving method in the air has been described above, other dissolving methods can be used.
The case of melting in an Ar atmosphere will be described. First, in an Ar atmosphere (400 to 600 Torr), Ag
-Au-X (X is Cu, Al, Ti, Pd, Ni,
V, Ta, W, Mo, Cr, Ru, Mg) alloys are melted and mixed by arc melting to prepare a master alloy.

Next, the above-mentioned mother alloy and Ag are melted in a high-frequency melting furnace. The amount of Ag at this time is defined as the amount obtained by subtracting the amount of Ag in the master alloy from the total dissolved amount. The crucible containing the mother alloy and Ag is placed in a high-frequency melting furnace and evacuated. After drawing a vacuum to the extent that oxygen is not involved,
The melting is started after setting the melting furnace in an Ar atmosphere (100 to 600 Torr). The melting temperature at this time is, for example, 10
The temperature is 50 to 1400 ° C., and the crucible is, for example, 0.1 to 0.
A 2 liter normal graphite crucible is used.

Next, the molten material is poured into a Fe mold having an inner surface coated with, for example, alumina or magnesium talc. The Fe mold is previously heated to about 300 to 500 ° C. in an electric furnace or the like in order to prevent shrinkage cavities.

The melt in the mold is cooled and solidified, the ingot is removed from the mold, and cooled to room temperature. next,
The feeder at the top of the ingot is cut and removed, and the ingot is rolled by a rolling mill, and 90 mm × 90 mm × 8.1 m
A plate-shaped alloy of m is prepared.

Then, for example, in an electric furnace at 400 to 500 ° C.
, Heat treatment is performed for about 1 to 1.5 hours in a state in which Ar gas is sealed, and then warpage is corrected by a press machine.

Thereafter, the product is cut into a wire, the entire surface of the product is polished with a water-resistant abrasive paper, the surface roughness is adjusted, and finally the Ag alloy sputtering target material of the present invention can be manufactured.

As described above, in the case of manufacturing the sputtering target material of the Ag alloy of the present invention, even when adding Au and other elements X to Ag and melting it, the conventional easy-to-use method is used. The method can be applied, and there are great advantages in terms of price and recipe.

The present invention is not limited to the above embodiment, but can be implemented with various modifications.

[0058]

The sputtering target material of the present invention can secure higher durability against oxygen, sulfur, chlorine and the like as compared with Ag. Therefore, by forming a thin film using this sputtering target material, it was possible to obtain a high-quality optical recording medium capable of avoiding deterioration of a reproduced signal for a long time.

Further, the thin film formed by using the sputtering target material of the present invention and the optical recording medium having the thin film can ensure a high reflectance, can obtain a good reproduction signal, and have a high quality. Optical recording medium was obtained.

The sputtering target material of the present invention comprises:
When a thin film is formed by a sputtering method using this, the sputtering rate does not decrease so much as compared with the case where a thin film is formed by a sputtering method using Ag alone, and compared with Au and Al as alternative materials. Then, it turned out that it is more excellent in a sputtering rate.

The sputtering target material of the present invention comprises:
A product can be manufactured by a simple melting method conventionally used, and a thin film for an optical recording medium can be easily formed by applying a sputtering method.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an example of an optical recording medium having a thin film formed using a sputtering target material according to an embodiment of the present invention and having a two-layer structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... 1st board | substrate 2 ... 2nd board | substrate 10 ... Optical recording medium 11 ... 1st information recording layer 12 ... 2nd information recording layer 15 ... Translucent film 16 ... Silver alloy reflective film 20 ... Photocurable resin 21: first fine unevenness 22: second fine unevenness 30: protective film

Claims (3)

[Claims] 1. An alloy containing Ag as a main component, containing Au in an amount of 0.1 wt% or more and 5.0 wt% or less, Cu, Al, Ti, Pd, Ni, V, Ta, W, Mo,
At least one selected from the group consisting of Cr, Ru, and Mg
A sputtering target material for forming a thin film, wherein the sputtering target material contains at least 0.1 wt% and at most 5.0 wt% of elements, and is made of a metal material containing at least these elements. 2. An alloy containing Ag as a main component, containing Au in an amount of 0.1 wt% or more and 5.0 wt% or less, Cu, Al, Ti, Pd, Ni, V, Ta, W, Mo,
At least one selected from the group consisting of Cr, Ru, and Mg
A thin film containing at least 0.1 wt% and not more than 5.0 wt% of elements, and formed using a metal material containing at least these elements. 3. An alloy containing Ag as a main component, containing Au in an amount of 0.1 wt% or more and 5.0 wt% or less, Cu, Al, Ti, Pd, Ni, V, Ta, W, Mo,
At least one selected from the group consisting of Cr, Ru, and Mg
An optical recording medium containing at least 0.1 wt% and not more than 5.0 wt% of at least one kind of element, and having a thin film formed using a metal material containing at least these elements.