JP2000109943A - Sputtering target material for thin film formation, thin film formed by using it and optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a thin film having high weatherability and free from the generation of deterioration in reproduced signals by using the one obtd. by incorporating a specified amt. of Pd into Ag as a sputtering target material. SOLUTION: Preferably, this material is an Ag alloy in which Ag is incorporated with 0.5 to 4.9 atomic % Pd, and one or two kinds of elements of Cu and Cr are moreover added thereto respectively by 0.1 to 3.5 atomic % or an Ag alloy in which Ag is incorporated with 0.5 to 1.5 atomic % Pd, and 0.1 to 2.9 atomic % Ti is moreover incorporated therein. For example, as to an optical recording medium 10, a 1st substrate 1 has 1st fine ruggedness 21 such as data recording pits or the like and a translucent film 15 to form a 1st information recording layer 13. A 2nd substrate similarly has 2nd fine ruggedness 22 and a reflecting film formed of a silver alloy to form a 2nd information recording layer 12. By applying light beams with different wavelength in such a manner that the focuses are connected onto the 1st and 2nd information recording layers 11 and 12, information is reproduced. By the interaction between Ag and Pd, high weatherability can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a sputtering target material for forming a thin film, a thin film formed using the same, and an optical recording medium.

[0002]

2. Description of the Related Art CDs (Compact Discs) and DVDs (Digi
optical disc such as tal Versatile Disc) or MD
Magneto-optical discs such as (Mini Disc) and MO (Magnetic Optical Disc), rewritable optical recording media such as phase-change optical discs, and the material of the reflective film applied to these optical recording media include Al and Al alloys. Is generally known.

[0003] When reproducing recorded information in the above-mentioned various optical recording media, the above-mentioned Al or Al alloy can provide a certain or more reflectance in a specific optical wavelength region, and
Excellent heat conduction properties. In addition, it is possible to obtain a stable coating property with respect to the fine unevenness grooves formed in the optical recording medium, and further, when the optical recording medium product is formed, weather resistance to non-metal elements contained in the air. It also has the advantage that the timekeeping change is extremely small over a long period of time.

[0004]

However, Al,
Alternatively, the reflectance of a thin film formed of an Al alloy is, for example, about 80% with respect to light having a wavelength of 800 nm, and it is considered that a sufficient reflectance is still obtained depending on the use of an optical recording medium. I can't say.

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.
It has been studied to apply Au as a material for the reflective film. 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 and sulfur, and these ions, and therefore has a problem in terms of weather resistance in a special environment such as seawater. Have.

On the other hand, Japanese Patent Laid-Open No. 57-186244,
JP-A-7-3363 and JP-A-9-156224 disclose a technique for improving the weather resistance by adding a predetermined impurity to Ag.
That is, JP-A-57-186244 discloses that AgC
As 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 clearly stated. In particular,
Improvement of weather resistance due to addition of a small amount of impurities to Ag has not been sufficiently achieved, and the reliability as a reflective film when employed in an optical recording medium is often unclear.

Further, Mg is an alkaline earth metal, and since elements or ions of this kind are chemically unstable, alloys using this are resistant to weathering to chlorine and the like. There was a need to improve.

In order to solve the above-mentioned problems in the prior art, the present inventors have maintained high reflectivity as compared with Ag, improved weather resistance, and made it easier to manufacture alloys.
As a result of intensive studies on various problems of stability and simplicity in the sputtering process when used as a sputtering target, a sputtering target material for forming a thin film capable of solving these problems and formation using the same. Thus, a thin film and an optical recording medium were obtained.

[0011]

In the present invention, Ag is used.
Ag containing 0.5 to 4.9 atomic% of Pd
A Pd alloy is used as a sputtering target material for forming a thin film, whereby a thin film constituting an optical recording medium is formed, and an optical recording medium having the thin film as a component is obtained.

In the present invention, Pd is added to Ag.
Is contained in an amount of 0.5 to 4.9 atomic%, and further, Cu, Cr
One or two of the elements are each 0.1.
Ag alloy containing 1 to 3.5 atomic%, or A
g contains 0.5 to 1.5 atomic% of Pd.
Is used as a sputtering target material for forming a thin film, thereby forming a thin film constituting an optical recording medium, and using the thin film as a component. Is what you get.

According to the AgPd alloy of the present invention, when applied as a sputtering target material for forming a thin film and a thin film for an optical recording medium, the hydrogen resistance and the oxygen resistance of Ag are improved.
Due to the interaction between Pd's chlorine resistance and sulfur resistance, it is required to be used for optical recording media and contamination by nonmetallic elements such as chlorine, hydrogen, oxygen and sulfur, which are examined in the air or special environment. It is possible to improve the high weather resistance in the environment and atmosphere to be performed.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, Pd is added to Ag.
Is used as a sputtering target material for forming a thin film, and further, a thin film constituting an optical recording medium is formed using this alloy. An optical recording medium as a component is obtained.

Further, in the present invention, Ag contains 0.5 to 4.9 atomic% of Pd, and one or two of Cu and Cr each contain 0.1 to 0.1 atomic%.
An Ag alloy containing 3.5 atomic% or an Ag alloy containing 0.5 to 1.5 atomic% of Pd and 0.1 to 2.9 atomic% of Ti in Ag A thin film constituting an optical recording medium is formed by using the alloy as a sputtering target material for formation, and an optical recording medium including the thin film as a component is obtained.

In the examples shown below, the sputtering target material for forming a thin film of the present invention, a thin film formed using the same, and an optical recording medium having this thin film have a structure having two information recording layers. A case in which the present invention is applied to a disk-shaped, so-called disk-shaped optical disk will be described. The present invention can be applied to various optical recording media having a metal thin film in an information layer, such as a shape.

As shown in FIG. 1, an optical recording medium manufactured in the following example includes a first substrate 1 and a second substrate 2.
Is an optical recording medium having a two-layer structure in which, for example, light-transmitting, photocurable resin 20 is interposed.

The first substrate 1 is formed, for example, by injection molding of a light-transmissive resin such as polycarbonate on one principal surface of a first fine unevenness 21 such as a data recording pit or a pre-groove.
And a semitransparent film 15 on which the first information recording layer 13 is formed.

Further, similarly to the first substrate 1, the second substrate 2 laminated on the above-mentioned first substrate 1 is formed on one principal surface by injection molding of a light transmitting resin such as polycarbonate. It has the second fine irregularities 22 such as recording pits or pregrooves, on which the 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.

When reproducing information recorded on the second information recording layer 12 in the optical recording medium having a two-layer structure shown in FIG.
The information recording layer 12 is focused on, 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.
Will be described.

As described above, the present invention is intended to maintain high reflectance, improve weather resistance, and facilitate production of alloys.
In order to solve various problems of stability and simplicity in a sputtering process when used as a sputtering target, Pd is 0.5 to 4.9 in Ag.
A sputtering target material for forming a thin film of an AgPd alloy containing at.%, A thin film formed by using the same, and an optical recording medium having the thin film.

Further, the present invention provides a method wherein the Pd is 0.5 to
Ag, Pd alloy containing 4.9 atomic% contains Cu, C
Ag alloy, or Ag containing 0.5 to 1.5 atomic% of Ag, wherein one or two elements of r are each added in an amount of 0.1 to 3.5 atomic%.
A sputtering target material for forming a thin film of an Ag alloy containing 0.1 to 2.9 atomic% of Ti, a thin film formed by using the same, and an optical element having a thin film formed by the alloy A recording medium is obtained.

Pd was particularly selected as the sputtering target material for the silver alloy according to the present invention because the specific gravity of silver was 10.491 [g / cm ³ ] and the Pd was 1
2.02 [g / cm ³ ], and the difference between the two is extremely small. As described above, when the difference in specific gravity is small, segregation of Pd, which is an additive element, in the entire alloy during the melting process when producing the alloy and when the alloy is cooled and solidified can be suppressed. Alternatively, there is an advantage that an intermetallic compound is not formed during the step of manufacturing an alloy.

Ag easily bonds to sulfur, and if left in the air for a long time, the interface in contact with the air reacts with sulfur to become 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, the reflection characteristics further deteriorate, and the physical characteristics of Ag are impaired. 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 when the state of bonding with hydrogen was confirmed after being immersed in water and allowed to stand, it was found that the reactivity with hydrogen was 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.

On the other hand, Pd is an element that is resistant to the reaction of sulfur and chlorine unless it reaches a high temperature, and is chemically stable to chlorine and sulfur. However, due to the property that hydrogen is well absorbed and activated, a small amount of Ti is often added as a barrier material to hydrogen when producing a plate material by a melting method.

As described above, by adding a certain amount of Pd to Ag and dispersing Pd uniformly into the grain boundaries of Ag, when Ag-Pd alloy is formed, the hydrogen resistance and oxygen resistance of Ag are improved. Due to the interaction of Pd, chlorine resistance and sulfur resistance, when it is used for contamination by optical elements such as chlorine, hydrogen, oxygen, and sulfur, which are considered in the air or special environments, such as non-metal elements. This makes it possible to realize a higher improvement in weather resistance as compared with Ag under the required environment and atmosphere.

Next, Ag obtained by adding a predetermined amount of Pd to Ag is used.
A thin film for an optical recording medium, that is,
In the case where an optical recording medium was manufactured by forming a reflective film, the reflectance with respect to laser light of a predetermined wavelength was measured. In this case, Pd is 0.1, 0.5, 1.0, 1.
5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.
A thin film of an optical recording medium, that is, a reflective film is formed by using a sputtering target material for forming a thin film of an AgPd alloy in an amount of 5, 5.0 [atomic%]. , Wavelength 800, 600, 40
The reflectivity of each of the samples when irradiated with a laser beam of 0 [nm] is measured. The measurement results are shown in the following (Table 1).

[0030]

[Table 1]

From the measurement results shown in (Table 1), Ag
Containing 0.5 to 4.9 [atomic%] of Pd
It can be seen that when a thin film of an optical recording medium is formed using a sputtering target material for forming a thin film of a gPd alloy, a practically desirable high reflectance is obtained. That is, as shown in (Table 1), Pd is contained in Ag,
In the case where a thin film of an optical recording medium is formed using a sputtering target material for forming a thin film of an AgPd alloy containing 0.5 to 4.9 [atomic%], particularly, a laser beam having a wavelength of 800 [nm]. Irradiates a high reflectance of 88% or more, indicating that the 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 AgPd alloy containing 0.5 to 4.9 [atomic%] of Pd in Ag is used as a material for forming a reflective film of an optical recording medium. Can reduce the reflectivity to a maximum of about 4 to 5% as measured in the same wavelength region as compared with a case where Ag is used alone. Further, with respect to the weather resistance, which is important as a reflection film of an optical recording medium, the addition of Pd can further improve the weather resistance as compared with the case where Ag is used alone.

Next, an AgPd alloy containing 0.5 to 4.9 atomic% of Pd in Ag contains 0.1 to 3.5 atomic% of either Cu or Cr, respectively. % To obtain an AgPdX (X is Cu, Cr) alloy, a reflective film of an optical recording medium was formed with this alloy, and the reflectance of the optical recording medium with respect to laser light having a predetermined wavelength was measured. .

In this case, the wavelengths 800, 600, 400
The reflectance was measured when each laser beam was irradiated with [nm], and the measurement results are shown in the following (Table 2).
Shown in

[0035]

[Table 2]

As shown in Table 2, Pd is added to Ag.
Is contained in 0.5 to 4.9 [atomic%] of AgPd.
AgPdX (X is C) obtained by adding 0.1 to 3.5 atomic% of each of Cu and Cr to the alloy.
u, Cr) alloy or Ag with 0.5 to 1.5 Pd
In the case where a thin film of an optical recording medium is formed using a sputtering target material for forming a thin film of an Ag alloy containing 0.1% to 2.9% by atom of Ti and 0.1% to 2.9% by atom of Ti, it is practically high. It can be seen that the reflectance can be obtained.

That is, as shown in (Table 2),
When a laser beam having a wavelength of 800 [nm] is irradiated, A
AgPdX obtained by adding 0.1 to 3.5 atomic% of any one of Cu and Cr to a gPd alloy, respectively.
(X is Cu, Cr) alloy or Ag with Pd 0.5
１．５1.5 at.%, And 0.1-2.9 at.
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 containing at.%, A high reflectance of 88% or more is obtained, which is excellent as a reflection film of the optical recording medium. What has the characteristic which was obtained can be obtained.

In the above, AgPd alloy is
The case where any one of Cu and Cr is contained has been described. However, the present invention is not limited to this example. It has been confirmed that the same effect can be obtained with an alloy containing 1 to 3.5 atomic%.

In addition, 0.1 to 1.5 atomic% of Pd is added to Ag.
It has been confirmed that the same effect can be obtained also in an alloy containing 0.1 to 2.9 atomic% of Ti in the contained AgPd alloy.

In addition, Table 2 shows a case where the AgPd alloy contains any of Cu, Ti and Cr. However, the present invention is not limited to this example. No, other than Cu, Ti, Cr, for example, A
The present invention can also be applied to an AgPd alloy containing one or more of u, Al, and Rh, and even when these are used, a high reflectance can be obtained and the reflection of the optical recording medium can be obtained. It was confirmed that a film having excellent characteristics could be obtained.

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

For example, a cylindrical AgPd alloy having a diameter of 76.2 mm and a height of 6 mm, and the Pd content is 2
Prepare the atom%. Next, for example, the diameter 7
Au, Al, C with a cylindrical shape of 6.2 mm and a height of 6 mm
A pure metal of u, Ti, Rh, Cr is prepared.

Each of these was set in a sputtering apparatus, and an AgPd alloy and Au and A as the second additive elements were added.
Pure metals of l, Cu, Ti, Rh, and Cr are simultaneously discharged to form a ternary alloy film (hereinafter, referred to as an AgPdX alloy).

In this case, a reflective film was formed using Ag alone or an AgPd alloy alone, and Al and Au which could be considered as alternative materials, and the sputter rate was measured to compare the rate difference. If you do. The thickness of each film is 1000 mm, and R
The film was formed by the F magnetron sputtering method. In addition, Ag
In the PdX alloy, the content of the X metal is, for example, 3 atomic%.

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

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

[0047]

[Table 3]

As shown in Table 3, when a thin film was formed using the Ag alloy of the present invention, that is, the AgPd alloy and the AgPdX alloy, the thin film was formed as compared with the case where Ag was used alone. Although the film formation time increases by about 50%, the film formation time can be remarkably shortened 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. A
When the g alloy is produced by the 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. Should 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
-Pd-X (X is Au, Al, Cu, Ti, Rh, C
r) The alloy is melted and mixed by arc melting to produce a master alloy. At this time, Pd is 10 to 15 with Ag being an absolute amount.
[Atomic%], X (X is Au, Al, Cu, Ti, Rh,
Cr) is melted at a composition of 15 to 20 atomic%.

Next, Ag is melted in a high-frequency melting furnace. The amount of Ag at this time is the amount obtained by subtracting the amount of Ag in the mother alloy from the total amount of dissolution. The melting temperature at this time is, for example, 1000 to 1500 ° C.
A 1-0.2 [liter] parallel 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 one 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 2000 ° C.
And

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 taken out of the mold and cooled to room temperature. next,
The uppermost feeder section of the ingot is cut and removed, and the ingot is rolled by a rolling mill to obtain 90 mm × 90 mm ×
A plate-shaped alloy of 8.1 [mm] is prepared.

Then, for example, in an electric furnace at 400 to 500 ° C.
Then, 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, and the entire surface of the product is polished with a water-resistant abrasive paper to adjust the surface roughness. Finally, the Ag alloy sputtering target material of the present invention can be manufactured.

As described above, when producing the Ag alloy sputtering target material of the present invention, even when Pd and other elements X are added to Ag and melted, the conventional simple method is used. The method can be applied, and there are great advantages in terms of price and recipe.

In the above-described example, in Table 2, Ag contained Pd in an amount of 0.5 to 4.9 at%, and Cu and Cr in an amount of 0.1 to 3.5 at% respectively. The added alloy and / or Ag contains 0.5 to 1.5 atomic% of Pd, and further contains 0.1 to 0.1% of Ti.
Although an Ag alloy containing 2.9 atomic% has been described, the present invention is not limited to this example.
The same applies to u, Al, and Rh. That is, in the AgPd alloy, a part of Ag is converted to Au, Al,
It has been confirmed that a high reflectivity is exhibited even when an alloy is prepared by substituting Rh and forming a thin film of an optical recording medium by using the alloy. This is different from the case where an alloy is prepared using Cu, Ti, and Cr. Similarly, a sputtering target material, a thin film for an optical recording medium, and an optical recording medium having excellent effects can be manufactured.

[0060]

The sputtering target material of the present invention can secure higher durability against oxygen, sulfur, chlorine and the like as compared with Ag. By performing the above, a high-quality optical recording medium capable of avoiding deterioration of a reproduced signal for a long period of time was obtained.

The thin film formed by using the sputtering target material of the present invention and the optical recording medium having the same have a reflectance of 88% when the wavelength is less than 800 nm.
The above high reflectivity could be secured, a good reproduction signal could be obtained, and a high quality optical recording medium could be obtained.

When the AgPd alloy of the present invention is used to form a thin film by the sputtering method using the sputtering target material, the sputtering rate is much lower than when the thin film is formed by the sputtering method using Ag alone. No, and it was found that the sputtering rate was superior to that of Au or Al as an alternative material.

The sputtering target material of the present invention
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.

[0064]

[Brief description of the drawings]

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

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 1st board | substrate, 2 2nd board | substrates, 10 optical recording media, 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

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G11B 11/10 523 G11B 11/10 523 541 541H (72) Inventor Katsuhisa Araya 6-7-35 Kita Shinagawa, Shinagawa-ku, Tokyo No. Sony Corporation F term (reference) 4K029 BA22 BD00 CA05 DC04 5D029 MA13 5D075 EE03 FG01 GG03 5D121 AA05 EE03 EE09 EE14

Claims (9)

[Claims] 1. The method according to claim 1, wherein Pd is 0.5 to 4.9 atomic% in Ag.
A sputtering target material for forming a thin film of an AgPd alloy, characterized by being contained. 2. Ag has a Pd content of 0.5 to 4.9 atomic%.
A thin film formed by using a contained AgPd alloy. 3. Ag containing 0.5 to 4.9 atomic% of Pd.
An optical recording medium having a thin film formed using an AgPd alloy contained therein. 4. The AgPd alloy thin film according to claim 1, wherein one or two of Cu and Cr are contained in an amount of 0.1 to 3.5 atomic%, respectively. Sputtering target material for formation. 5. The AgPd alloy according to claim 2, wherein one or two of Cu and Cr are contained in an amount of 0.1 to 3.5 atomic%, respectively. Formed thin film. 6. The AgPd alloy according to claim 3, wherein one or two of Cu and Cr are contained in an amount of 0.1 to 3.5 atomic%, respectively. An optical recording medium having a thin film formed by: 7. Ag containing 0.1 to 1.5 atomic% of Pd;
A sputtering target material for forming a thin film of an AgPdTi alloy, characterized by containing 0.1 to 2.9 atomic% of Ti. 8. Ag containing 0.1 to 1.5 atomic% of Pd;
A thin film formed using an AgPdTi alloy, characterized by containing 0.1 to 2.9 atomic% of Ti. 9. Ag has a Pd content of 0.1 to 1.5 atomic%,
An optical recording medium having a thin film formed using an AgPdTi alloy, characterized by containing 0.1 to 2.9 atomic% of Ti.