JP2003160859A - Silver alloy sputtering target for forming reflection coat on optical recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver alloy sputtering target for forming a reflection coat on an optical recording medium such as optical recording disks (CD-RW and DVD-RAM). <P>SOLUTION: The silver alloy sputtering target for forming the reflection coat on the optical recording medium comprises one or two of In and Sn in amounts of 0.5-15 mass% in total, further one or more of Cr, Co and Ni in amounts of 0.01-5 mass% in total, and the balance Ag. The reflection coat on the optical recording medium formed by sputtering the target hardly changes with time. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silver alloy sputtering target for forming a reflective film of an optical recording medium such as an optical recording disk (CD-RW, DVD-RAM).

[0002]

2. Description of the Related Art Conventionally, optical recording disks (CD-RW, D
An Ag reflection film is used as a reflection film of an optical recording medium such as a VD-RAM), and the Ag reflection film is 400 to 83.
It is widely used because it has a high reflectance in a wide wavelength range of 0 nm and is particularly excellent in reflectance for short-wavelength laser light such as blue laser light as compared with other metal reflection films. However, when the recording medium is a rewritable phase change type, it is necessary that the reflective film can easily control the thermal conductivity according to the linear velocity of the recording medium.
The reflective film has a drawback that the thermal conductivity is too good. Therefore, a reflective film having a high reflectance and a low thermal conductivity is required, and as an example of the reflective film having a high reflectance and a low thermal conductivity, Ag, Cu, Mg, Zn, Sn, Bi, In,
A reflective film made of an Ag alloy containing at least one of Ti, Zr, Au, Pd and Pt is known (Japanese Patent Laid-Open No. 2001-2001).
-35014), and Ag-In, Ag-.
A reflective film made of an alloy such as V or Ag-Nb is known (see Japanese Patent Laid-Open No. 6-243509).

[0003]

However, all of these conventional Ag alloy reflective films have insufficient surface weather resistance, so that the reflectance decreases with the passage of time, and a blue laser having a particularly short wavelength is used. There has been a problem that the reflectance for light is remarkably lowered and the performance as a reflection film of an optical recording medium is lowered in a short period of time.

[0004]

The inventors of the present invention have conducted research to obtain an Ag alloy reflective film that is less likely to change over time. As a result, (a) In: 0.5 to 15% by mass, and Silver obtained by sputtering using a target made of a silver alloy having a composition of 0.01 to 5 mass% in total of one or more of Cr, Co and Ni, and the balance being Ag. In the alloy reflection film, the decrease in reflectance due to aging is extremely small. (B) Since Sn contained in Ag has the same action as In, a part or all of In contained in the silver alloy in (a) is removed. The result of the study was that it could be replaced by Sn.

The present invention was made on the basis of the results of such research. (1) One or two of In and Sn are contained in a total amount of 0.5 to 15% by mass, and Cr is further added. , Co, Ni, one or more of which are contained in a total amount of 0.01 to 5% by mass, and the balance being Ag alloy having a composition of Ag alloy, and a silver alloy sputtering target for forming a reflective film of an optical recording medium, (2) A reflective film of an optical recording medium which is formed by sputtering the target according to the above (1) and has little change over time.

The sputtering target for forming the silver alloy reflective film of the present invention is a Ag alloy prepared by melting high-purity Ag in a vacuum or an inert gas atmosphere and adding In and / or Sn to the obtained molten metal. A molten metal is prepared, and a Cr-Ag mother alloy, a Co-Ag mother alloy, and a Ni-Ag mother alloy, which have been prepared in advance, are added to this molten Ag alloy, and a vacuum is applied so as to form an Ag alloy having a predetermined composition. Alternatively, by melting in an inert gas atmosphere, casting the molten metal thus obtained in a vacuum or in an inert gas atmosphere to prepare an ingot, and hot-working the obtained ingot and then machining it. It can be manufactured.

Next, the reason why the component composition of the sputtering target made of the Ag alloy of the present invention and the Ag alloy reflective film formed by using the target is limited as described above will be explained.

In, Sn: These components have the effect of preventing the reflectance of the Ag alloy reflective film from changing with time.
If these components are contained in an amount of less than 0.5% by mass, sufficient weather resistance cannot be obtained. On the other hand, if they are contained in an amount of more than 15% by mass, the initial reflectance of the Ag alloy reflective film will decrease, which is not preferable. Therefore, the content of these components contained in the Ag alloy reflective film and the sputtering target for forming this Ag alloy reflective film is set to 0.5 to 15% by mass (more preferably 5 to 10% by mass).

Cr, Co, Ni: These components further enhance the weather resistance of the Ag alloy reflective film containing one or two of In and Sn in a total amount of 0.5 to 15 mass%, and reflectivity. Is a component that prevents the change over time, but further weather resistance cannot be obtained even if the total amount of one or more of these components is less than 0.01% by mass. When two or more kinds are contained in a total amount of more than 5% by mass,
Although the weather resistance is further improved, the initial reflectance of the Ag alloy reflective film is lowered, which is not preferable.
Therefore, the content of these components contained in the Ag alloy reflective film and the sputtering target for forming the Ag alloy reflective film is set to 0.01 to 5 mass% (more preferably 0.5 to 3 mass%). .

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As a raw material, Ag, In, and Sn are melted in a high-frequency induction heating furnace in an Ar atmosphere, and the obtained melt is made of Cr-Ag prepared in advance using a plasma arc melting furnace. Mother alloy, Co-Ag mother alloy, Ni-A
g mother alloy is added to prepare molten Ag alloy,
Diameter: 1 by casting molten alloy in Ar atmosphere
An ingot having dimensions of 00 mm and length: 90 mm was produced. This ingot is cut into slices in diameter:
A disk having a size of 100 mm and a thickness of 30 mm is prepared, and the disk is hot-rolled at 600 ° C. to prepare a rolled plate having a size of 6 mm, and machined. Due to this, diameter: 200 mm, thickness: 5
The present invention silver alloy sputtering target (hereinafter referred to as the present invention target) 1 to 23 and the comparative silver alloy sputtering target (hereinafter referred to as the comparative target) 1 to 6 having a size of mm and having the composition shown in Tables 1 and 2. And a conventional silver alloy sputtering target (hereinafter referred to as a conventional target) was produced.

The target 1 of the present invention thus obtained
23 to 23, comparative targets 1 to 6 and conventional target, respectively, were placed on a cooling plate made of oxygen-free copper having a thickness of 10 mm and In-S.
After soldering with n eutectic solder, it was attached to a normal DC magnetron sputtering device, and a polycarbonate resin plate having a diameter of 120 mm and a thickness of 1.2 mm was placed at a distance of 7 cm between the target and the substrate.
Set so that the inside of the chamber is 1 × 10 ⁻⁴ Pa.
After evacuating to a vacuum, argon gas was introduced into the chamber until the pressure became 0.5 Pa, and sputtering was performed for 40 seconds under the condition of DC power: 100 W to form a reflective film having a film thickness of 100 nm.

Laser light having wavelengths of 405 nm and 650 nm is applied to these reflective films to measure the reflectance with an ellipsometer, and then the reflective films are placed in a constant temperature and humidity container (80
C., 85%) for 200 hours, and then similarly irradiated with laser beams having wavelengths of 405 nm and 650 nm to measure the reflectance with an ellipsometer.
The weather resistance of the reflective film was evaluated as shown in FIG.

[0013]

[Table 1]

[0014]

[Table 2]

From the results shown in Tables 1 and 2, the reflective films obtained by performing the sputtering using the targets 1 to 23 of the present invention are comparative targets 1 to 6.
Further, it can be seen that the weather resistance is excellent because the reflectance is less deteriorated as compared with the reflective film obtained by performing the sputtering using the conventional target.

[0016]

As described above, the reflection film prepared by using the silver alloy sputtering target for forming the reflection film of the optical recording medium of the present invention uses the conventional silver alloy sputtering target for forming the reflection film of the optical recording medium. Compared with the reflective film prepared by the above, there is less decrease in reflectance due to aging, and it is possible to manufacture an optical recording medium that can be used for a long time.
It can greatly contribute to the development of the media industry.

Claims (2)

[Claims] 1. A total of 0.5 to 15 mass% of one or two of In and Sn, and Cr, Co, N.
A silver alloy sputtering for forming a reflective film of an optical recording medium, which is composed of a silver alloy having a composition containing 0.01 to 5 mass% of one or more of i in total, with the balance being Ag. target. 2. A reflective film for an optical recording medium, which is formed by sputtering the target according to claim 1 and has little change over time.