JP2003293055A - Silver alloy thin film and silver alloy for forming thin film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a silver alloy thin film which has a high reflectivity, is excellent in the uniformity of the reflectivity, and also has a reduced change with the lapse of time, i.e., the one which is suitably used for a reflection film of an optical recording disk dealing with high recording density or of a display device dealing with a high definition screen, and to provide a silver alloy which is suitably used for forming the silver alloy thin film. <P>SOLUTION: The silver alloy thin film contains 0.01 to 0.1 atomic % of one or more kinds of metals selected from Pd and Pt, and, if required, containing one or more kinds of metals selected from Zn, Mg and Cu, and the balance Ag with inevitable impurities. The silver alloy suitably used for the production of the same has the same componential composition. <P>COPYRIGHT: (C)2004,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 thin film suitable for use as a reflective film of various optical recording disks and display device devices, and a silver alloy suitable for use in the production of the silver alloy thin film.

[0002]

2. Description of the Related Art Various optical recording discs such as CDs, DVDs, and MODs that read information recorded on discs using optical signals,
Various display device devices such as LCDs, PDPs, and ELs for displaying image information use a reflective film having a thickness of several hundred Å to several thousand Å formed by a method such as sputtering or vapor deposition.

The reflective film is required to have characteristics such as high reflectance, uniform reflectance within the surface, and small change in reflectance over time. Therefore, conventionally, Al, Au,
Metallic thin films consisting of Ag and their alloys have been mainly used.

In recent years, in response to higher recording density and higher definition of optical recording disks and display device devices, there is an increasing demand for a reflective film having a higher reflectance and a more uniform reflectance. .

It has been clarified that the above-mentioned required characteristics cannot be satisfied because the reflective film made of Al and Al alloy has a low reflectance. Further, the reflective film made of Au and Au alloy may satisfy the above required characteristics,
Since the price is very high, it is difficult to use it in a commercially available optical recording disk or display device.

[0006]

Among the conventional reflection films, the reflection film made of Ag and Ag alloy is a preferable material in that it has high reflectance. However, in particular, the reflective film made of pure Ag could not sufficiently satisfy the required characteristics in terms of uniformity of reflectance and change with time.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a silver alloy thin film having a high reflectance, an excellent reflectance uniformity, and a small change with time, in other words, an optical recording corresponding to a high recording density. It is intended to provide a silver alloy thin film suitable for use as a reflective film of a display device for a disk or a high-definition screen, and to provide a silver alloy suitable for use in manufacturing the silver alloy thin film.

[0008]

The silver alloy thin film of the present invention comprises:
According to one characteristic, at least one of Pd and Pt is 0.01-
Containing 0.1 atom%, the balance consisting of Ag and unavoidable impurities.
The reflectance is preferably 90% or more, more preferably 95% or more.

According to another characteristic, the silver alloy thin film of the present invention comprises 0.01 to 0.1 atom% of at least one of Pd and Pt, and 0.1 to 5 at least one of Zn, Mg and Cu. Containing atomic% and the balance consisting of Ag and unavoidable impurities. 90 reflectance
% Or more is preferable, and 95% or more is more preferable.

The silver alloy thin film of the present invention is suitable for a reflective film, an electrode film or a light-shielding film.

According to one characteristic, the silver alloy for producing a thin film of the present invention contains 0.01 to 0.1 atom% of at least one of Pd and Pt, and the balance comprises Ag and unavoidable impurities.

According to another characteristic, the silver alloy for producing a thin film of the present invention comprises 0.01 to 0.1 atom of at least one of Pd and Pt.
%, And 0.1 to 5 atomic% of one or more of Zn, Mg and Cu, and the balance Ag and inevitable impurities.

The present invention is suitable for a silver alloy sputtering target for thin film production or a vapor deposition source.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various studies to achieve the above object, the present inventor found the following items (1) to (3) and arrived at the present invention.

(1) The reflectance uniformity of a pure Ag reflective film is inferior because the crystal grains of a target used as a raw material when forming the reflective film by a sputtering method are coarse, (A) The variation in film thickness and (b) variation in the Ag crystal grain size are likely to be large.

(2) The reason why the reflectance of a pure Ag reflective film has a large change with time (the stability of the pure Ag reflective film is poor) is (a) heat resistance, especially in the environment where the reflective film is used. This is because Ag crystal grains in the reflective film are likely to be coarsened due to the influence of (2), and (b) with respect to corrosion resistance, the reflective film is easily corroded mainly by sulfurization of Ag.

(3) Addition of Pd, Pt, Zn, Mg, and Cu is effective as a measure against the above (1) and (2).

That is, according to one characteristic, the silver alloy thin film of the present invention contains 0.01 to 0.1% of at least one of Pd and Pt.
Containing 1 atom%, the balance consisting of Ag and unavoidable impurities. According to another feature, one or more of Pd and Pt
0.01 to 0.1 atom% and 0.1 to 5 atom% of at least one of Zn, Mg and Cu, and the balance Ag and inevitable impurities. The silver alloy thin film has high reflectance, excellent uniformity of reflectance, and little change over time.

The fact that the uniformity of the reflectance is excellent means that the variation of the reflectance is small.
Here, the meaning of the variation in reflectance is as follows. That is, the reflectance is measured by a spectrophotometer using light having a wavelength of 650 nm at 30 points in different places in the thin film sample. The difference between the maximum value and the minimum value of the data of 30 points thus obtained is defined as the dispersion of the reflectance.

The silver alloy thin film of the present invention is used, for example, for a reflective film of an optical recording disk, a reflective film of a display device, an electrode film, and a light-shielding film.

According to one characteristic, the silver alloy for producing a thin film of the present invention contains 0.01 to 0.1 atom% of at least one of Pd and Pt, and the balance comprises Ag and inevitable impurities. According to another feature, one or more of Pd and Pt
0.01 to 0.1 atom% and 0.1 to 5 atom% of at least one of Zn, Mg and Cu, and the balance Ag and inevitable impurities.

The silver alloy for producing a thin film of the present invention is, for example, for a sputtering target or a vapor deposition source.

The silver alloy thin film of the present invention is formed by spattering or vapor deposition using the silver alloy for thin film production of the present invention as a raw material, contains at least one of Pd and Pt, or contains Pd and Pt. One or more of Zn, Mg and
Contains one or more of Cu. The reason why the silver alloy thin film of the present invention has high reflectance and is excellent in uniformity of reflectance, heat resistance and corrosion resistance is as follows (1) to (4).

(1) Since the crystal grains of the silver alloy for producing a thin film of the present invention are made fine (average crystal grain size: 200 μm or less), the formed silver alloy thin films of the first and second inventions are: The variation in film thickness is small, and therefore the uniformity of reflectance is excellent. If the reflectance is uniform, the high reflectance originally possessed by the silver alloy is realized.

(2) Pd and Pt contained in the silver alloy thin film of the present invention make the crystal grains in the thin film finer and suppress coarsening of the crystal grains in the reflection film (variation of the crystal grain size of the thin film. , And its variation over time are reduced). Therefore, by adding at least one of Pt and Pd, the dispersion of the reflectance is reduced (the uniformity of the reflectance is improved and the reflectance is increased), and the heat resistance of the thin film is improved.

(3) Pd and Pt contained in the silver alloy thin film of the present invention also improve the corrosion resistance of the thin film.

(4) Z contained in the silver alloy thin film of the second invention
n, Mg and Cu further improve the corrosion resistance.

At least one of Pd and Pt is 0.01 atom%
If it is less than 1, the above-mentioned one or more of the above-mentioned effects cannot be sufficiently obtained,
On the other hand, if it exceeds 0.1 atom%, the above-mentioned one or more of the above-mentioned effects will not be increased. On the other hand, if it exceeds 0.1 atom%, the etching property required particularly for display device applications is deteriorated. Therefore, it becomes difficult to form a pattern on a thin film by etching with an etcher suitable for manufacturing a display device. At this time, etching can be performed by using an etcher having a strong etching power. However, in that case, materials other than the thin film are simultaneously etched, which complicates the manufacturing process and raises the cost.

If at least one of Zn, Mg and Cu is less than 0.1 atomic%, the corrosion resistance improving action of at least one of them cannot be sufficiently obtained. On the other hand, when it exceeds 5 atomic%, the decrease in reflectance becomes large.

The silver alloy thin film of the present invention is suitable for a reflective film of an optical recording disk or a display device.
Further, the high reflectance, the excellent corrosion resistance, the excellent etching property, and the low electric resistance having a purity close to that of pure Ag are suitable for the electrode film of the display device and the light-shielding film. is there.

The silver alloy thin film of the present invention can be formed from a thin film manufacturing raw material such as a sputtering target or a vapor deposition source which is the silver alloy for thin film manufacturing of the present invention. The component composition of this raw material may be substantially the same as that of the silver alloy thin film to be formed.

The silver alloy for producing a thin film of the present invention can be produced by a known alloy production method such as a powder metallurgy method or a melt casting method under appropriate plastic working conditions and heating conditions.

[0033]

Examples [Examples 1 to 12, Comparative Examples 1 to 6] Ag, Pd, Pt, Zn, Mg and Cu in the form of lumps having a purity of 99.99 atomic%
Was blended and the ingot was melted in a vacuum melting furnace. This ingot was hot-rolled and then cold-rolled and annealed repeatedly to obtain a target. This target was subjected to chemical analysis to measure the average crystal grain size. The average crystal grain size was determined by observing the broken structure. The results are shown in Table 1.

Next, using the above target, a magnetron sputtering method was performed to form a glass substrate having a thickness of 10 cm on a 10 cm square.
A 3000 Å thin film sample was formed. The thin film sample thus formed was subjected to chemical analysis to measure and evaluate reflectance, reflectance uniformity, heat resistance, corrosion resistance and etching property.

The reflectance is measured by a spectrophotometer at a wavelength.
Using 650 nm light, it was carried out at 30 different points in one thin film sample. An average value was obtained from the obtained data and used as the reflectance of the thin film sample. Further, the variation was obtained from the obtained data, and the smaller the variation was, the better the uniformity of reflectance was evaluated. The variation is the difference between the maximum value and the minimum value of the measured values at 30 points.

The above thin film sample (as-formed) at 500 ° C.
The reflectance of the thin film sample (after heating) obtained by performing the heat treatment for 0 seconds was measured in the same manner as above. The average value and the variation were obtained from the obtained data. Then, the average value of the as-deposited sample and the average value of the heated sample were compared, and the variation of the as-deposited sample and the variation of the heated sample were compared. That is, the change (difference) in average value and the change (difference) in variation due to the heat resistance test were examined. Thereby, the heat resistance of the as-deposited sample was comprehensively evaluated (the smaller the change in average value and the change in variation, the higher the heat resistance).

Regarding the corrosion resistance, the sample as-formed was used.
After standing in ZnS powder at room temperature for 1 hour, the reflectance was measured in the same manner as above. Then, the percentage (reduction rate (%)) of the decrease (difference) in which the reflectance thus left to decrease from the reflectance as deposited was calculated with respect to the reflectance as deposited. The smaller the reduction rate (%), the better the corrosion resistance was evaluated.

Regarding the etching property, after the etching pattern was formed using the photoresist, the second nitric acid solution was used.
Etching was performed using a cerium-ammonium-based aqueous solution. Then, when etching was performed according to the pattern and no film peeling or film corrosion was observed, the etching property was evaluated as “good”, and when not, the etching property was evaluated as “poor”.

Table 2 shows the results obtained as described above. The chemical analysis of the thin film sample was almost the same as the chemical analysis of the target.

[0040]

[Table 1]

[0041]

[Table 2]

From the above results, the following (1) to (6) can be seen.

(1) In Examples 1 to 12, the reflectance was high and the uniformity of the reflectance was excellent, and the change in reflectance and the variation in reflectance due to heating and acid were small (excellent in heat resistance and corrosion resistance). Moreover, a reflective film having excellent etching property is obtained.

(2) In Comparative Example 1, the crystal grains of the target became coarse (average crystal grain size: 213 μm) because Pd and Pt were not added, and the uniformity of reflectance and heat resistance of the thin film deteriorated. (Change (difference) in reflectance variation is large (5.9%)).

(3) In Comparative Examples 2 and 3, Pd (Comparative Example 2)
And since the Pt (Comparative Example 3) is too much, the etching properties of these thin films are deteriorated.

(4) In Comparative Example 4, the reflectivity and heat resistance of the thin film are reduced because the Zn content is too large (the change (difference) in the average reflectivity is large (2.5%)).

(5) In Comparative Example 5, the reflectance and the uniformity of reflectance of the thin film are deteriorated because the Mg content is too much.

(6) In Comparative Example 6, the reflectance of the thin film is lowered because the Cu content is too large.

[0049]

As is apparent from the above description, according to the present invention, a silver alloy thin film having a high reflectance, an excellent uniformity of the reflectance, and a small change with time, in other words, a high recording density can be obtained. It is possible to provide a silver alloy thin film suitable for use as a reflective film, an electrode film, a light-shielding film, or the like of an optical recording disk or a display device device compatible with a high-definition screen. Further, a silver alloy suitable for use in producing such a silver alloy thin film can be provided.

Claims (7)

[Claims] 1. One or more of Pd and Pt are added in an amount of 0.01-0.
A silver alloy thin film containing 1 atomic% and the balance Ag and inevitable impurities. 2. One or more of Pd and Pt are added in an amount of 0.01-0.
1 atomic% and at least one of Zn, Mg and Cu is 0.1
A silver alloy thin film containing ~ 5 atomic% and the balance Ag and inevitable impurities. 3. The silver alloy thin film according to claim 1, which has a reflectance of 90% or more. 4. The silver alloy thin film according to claim 1, which is for a reflective film, an electrode film, or a light-shielding film. 5. One or more of Pd and Pt are added in an amount of 0.01-0.
A silver alloy for thin film production, containing 1 atomic% and the balance Ag and inevitable impurities. 6. One or more of Pd and Pt are added in an amount of 0.01-0.
1 atomic% and at least one of Zn, Mg and Cu is 0.1
A silver alloy for thin film production, containing ~ 5 atom% and the balance Ag and inevitable impurities. 7. The silver alloy for producing a thin film according to claim 5, which is used for a sputtering target or an evaporation source.