JP6260321B2 - Sputtering target for Ag alloy film formation - Google Patents

Description

The present invention relates to an optical reflective layer such as a light-emitting element and the optical recording disk is used in the display and lighting, the Ag alloy film forming sputtering coater rodents bets for forming the Ag alloy film is used for wiring such as a touch panel It is related.

In general, a light reflecting layer is formed on a display such as an organic EL or a reflective liquid crystal, a light emitting element such as an LED, an optical recording disk, or the like for the purpose of improving light extraction efficiency. Here, an Ag film and an Ag alloy film made of Ag and an Ag alloy are widely used as the above-described light reflection layer because of their high reflectance. For example, Patent Document 1 discloses using Ag or an Ag alloy that reflects light with high efficiency as a constituent material of an electrode of a semiconductor light emitting element. Patent Document 2 discloses that an Ag alloy is used as a constituent material of a reflective electrode of an organic EL element. Patent Document 3 discloses that Ag or an Ag alloy is used as a constituent material of a reflection layer of an optical recording medium. In addition, the Ag film and the Ag alloy film are used not only for the above-described applications but also for reflection mirrors for optical devices, reflection films for solar cells, reflectors for lighting devices, and the like.
On the other hand, since the above Ag film and Ag alloy film have a low specific resistance value and excellent conductivity, they are also used as lead wires for touch panels, as disclosed in Patent Document 4, for example.

JP 2006-245230 A JP 2012-059576 A JP 2004-322556 A JP 2009-031705 A

  By the way, recently, with the increase in size of a glass substrate when manufacturing an organic EL element, wiring for a touch panel, etc., a sputtering target used for film formation is also increased in size. Here, when sputtering is performed by applying high power to a large sputtering target, a phenomenon called “splash” may occur due to abnormal discharge of the target. When this splash phenomenon occurs, there arises a problem that the melted fine particles adhere to the substrate and short-circuit the wiring and the electrodes, resulting in a significant decrease in yield. For this reason, even if it is a case where a large sized sputtering target is used, it is calculated | required to suppress abnormal discharge.

  In addition, in the above-described light-emitting elements and displays, high-temperature heat treatment may be performed in the manufacturing process, and thus the reflectivity of the Ag film or the Ag alloy film may deteriorate after the heat treatment, and sufficient characteristics may not be exhibited. there were. For this reason, there is a demand for an Ag alloy film that maintains a high reflectivity and a low specific resistance as close as possible to a pure Ag film and that does not deteriorate the reflectivity even after heat treatment.

The present invention has been made in view of the above-described circumstances, and has excellent optical characteristics such as reflectance and a low specific resistance value, excellent heat resistance, and optical properties such as reflectance even after heat treatment. it is possible to form an Ag alloy film characteristics are not significantly degraded, to provide an Ag alloy film forming sputtering coater Getting bets that can suppress the occurrence of any abnormal discharge when formed using a large-sized sputtering target For the purpose.

  In order to solve the above-mentioned problems, the sputtering target for forming an Ag alloy film of the present invention has Sb of 0.01 atomic% to 3.00 atomic% and Ca of 0.01 atomic% to 0.15 atomic%. It is characterized in that it has a composition composed of Ag and inevitable impurities.

In the sputtering target for forming an Ag alloy film of the present invention having such a configuration, the Sb content is 0.01 atomic% or more, so that the workability is improved by a synergistic effect with Ca described later. As a result, the processing trace of the target surface processing becomes fine and the surface roughness of the target surface becomes small, so that the occurrence of abnormal discharge during film formation can be suppressed. Moreover, the heat resistance of the formed Ag alloy film can be improved. Moreover, since the Sb content is 3.00 atomic% or less, the reflectance of the formed Ag alloy film can be increased and the specific resistance value can be decreased.
Furthermore, since the Ca content is 0.01 atomic% or more, the workability is improved, the surface roughness after surface processing of the target is reduced, and the occurrence of abnormal discharge during film formation can be suppressed. it can. Moreover, since content of Ca is 0.15 atomic% or less, generation | occurrence | production of the crack at the time of sputtering target manufacture can be suppressed.

Here, in the sputtering target for forming an Ag alloy film of the present invention, it is preferable that the atomic ratio of Sb and Ca contained is Sb / Ca ≧ 1.0.
According to the sputtering target for forming an Ag alloy film having this configuration, the surface roughness of the sputtering surface can be further reduced.

In the sputtering target for forming an Ag alloy film of the present invention, the arithmetic average roughness of the sputtering surface is preferably 1.0 μm or less, and the ten-point average roughness is preferably 6.0 μm or less.
According to the sputtering target for forming an Ag alloy film having this configuration, the arithmetic average roughness of the sputtering surface is 1.0 μm or less, and the ten-point average roughness is 6.0 μm or less. Generation | occurrence | production can be suppressed reliably.

As described above, according to the present invention, the optical characteristics such as reflectance are excellent and the specific resistance value is low, and the heat resistance is excellent. it is possible to form a large unchanged Ag alloy film, to provide an Ag alloy film forming sputtering coater Getting bets that can suppress the occurrence of any abnormal discharge when formed using a large-sized sputtering target it can.

Below, the sputtering target for Ag alloy film formation and Ag alloy film which are one Embodiment of this invention are demonstrated.
The sputtering target for Ag alloy film formation which is this embodiment is used when forming an Ag alloy film. Here, the Ag alloy film according to the present embodiment is, for example, an Ag alloy reflective film that constitutes a light reflective layer of a display, a light emitting element, or the like, or an Ag alloy conductive film that constitutes a wiring formed on the peripheral portion of the panel surface of the touch panel. used.

<Sputtering target for forming an Ag alloy film>
The sputtering target for forming an Ag alloy film according to the present embodiment contains 0.01 to 3.00 atomic% of Sb and 0.01 to 0.15 atomic% of Ca, with the balance being Ag. It is made of an Ag alloy having a composition composed of inevitable impurities.
Below, the reason which prescribed | regulated the composition of the sputtering target for Ag alloy film formation which is this embodiment as mentioned above is demonstrated.

(Sb: 0.01 atomic% or more and 3.00 atomic% or less)
Sb is an element that has the effect of suppressing the grain growth of Ag by dissolving in Ag and improving the workability of the Ag alloy constituting the sputtering target by a synergistic effect with Ca described later. As a result, the processing traces during surface processing become fine, the surface roughness of the target surface becomes small, and even when the sputtering target is enlarged, the occurrence of abnormal discharge during film formation can be suppressed. . Moreover, it also has the effect of improving the heat resistance of the formed Ag alloy film.
Here, when the content of Sb in the sputtering target is less than 0.01 atomic%, there is a possibility that the above-described effects cannot be sufficiently achieved. On the other hand, when the Sb content in the sputtering target exceeds less than 3.00 atomic%, the reflectance of the formed Ag alloy film may be low and the specific resistance value may be high.
For this reason, in this embodiment, the Sb content in the sputtering target is set in the range of 0.01 atomic% or more and 3.00 atomic% or less. In order to achieve the above-described effects and effects, it is preferable that the content of Sb in the sputtering target is in the range of 0.01 atomic% or more and 2.00 atomic% or less.

(Ca: 0.01 atomic% or more and 0.15 atomic% or less)
Ca is an element having an effect of improving the workability of the Ag alloy constituting the sputtering target when added.
Here, when the content of Ca in the sputtering target is less than 0.01 atomic%, the above-described effects may not be sufficiently achieved. On the other hand, when the content of Ca in the sputtering target exceeds 0.15 atomic%, the Ag alloy constituting the sputtering target is remarkably hardened, and there is a possibility that cracking or the like may occur during the production of the sputtering target.
For this reason, in this embodiment, the Ca content in the sputtering target is set within a range of 0.01 atomic% to 0.15 atomic%.
Further, the surface roughness of the sputtered surface can be further reduced by setting the Ca content to Sb / Ca ≧ 1.0 in terms of atomic ratio with respect to Sb.

<Ag alloy film>
As described above, the Ag alloy film according to the present embodiment is used as a light reflection layer of a display, a light emitting element or the like. In these applications, a high reflectance with respect to light of a specific wavelength or a high reflectance with respect to light in a wide wavelength range is required. Further, in the manufacturing process of a display or a light emitting element, a heat treatment at, for example, 250 ° C. or higher may be performed after the light reflecting layer is formed.
Furthermore, as described above, the Ag alloy film according to the present embodiment is used as an Ag alloy conductive film that forms a wiring formed on the peripheral portion of the panel surface of the touch panel. In these applications, a low specific resistance value is required.
Here, the Ag alloy film according to the present embodiment is formed using the above-described sputtering target for forming an Ag alloy film.

According to the sputtering target for forming an Ag alloy film of the present embodiment configured as described above, Sb is 0.01 atomic% or more and 3.00 atomic% or less, and Ca is 0.01 atomic% or more and 0.15. Since it is made of an Ag alloy having a composition of not more than atomic% and the balance being composed of Ag and inevitable impurities, the workability of the Ag alloy constituting the sputtering target is improved. As a result, the processing trace at the time of surface processing becomes fine, the surface roughness of the target surface becomes small, and even when the sputtering target is enlarged, the occurrence of abnormal discharge can be suppressed and the film formation can be stabilized. Can be implemented. In addition, it is possible to form an Ag alloy film having excellent optical characteristics such as reflectance, a low specific resistance value, and excellent heat resistance.
Further, since the Ca content is 0.15 atomic% or less, it is possible to suppress the Ag alloy constituting the sputtering target from being significantly hardened and causing cracks or the like during the production of the sputtering target. Therefore. A sputtering target for forming an Ag alloy film can be manufactured stably.

  In addition, the Ag alloy film according to the present embodiment is formed by the above-described sputtering target for forming an Ag alloy film, has excellent optical characteristics such as reflectance, has a low specific resistance value, and is excellent in heat resistance. Therefore, even when the heat treatment is performed at a relatively high temperature such as 250 ° C. or higher in the manufacturing process of the display or the light emitting element, the optical characteristics such as reflectance are not greatly deteriorated. For this reason, it is particularly suitable as an Ag alloy reflective film that constitutes a light reflection layer of a display, a light emitting element, etc., and an Ag alloy conductive film that constitutes a wiring formed on the peripheral portion of the panel surface of the touch panel.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, in the present embodiment, it has been described that the alloy is used as an Ag alloy reflective film that constitutes a light reflective layer of a display, a light emitting element, or the like, or an Ag alloy conductive film that constitutes a wiring formed in the peripheral portion of the panel surface of the touch panel. However, it is not limited to this, For example, you may apply to other uses, such as a translucent film | membrane used for a transparent conductive film or an infrared reflective film.

  Below, the result of the evaluation test evaluated about the effect of the sputtering target for Ag alloy film formation which concerns on this invention, and an Ag alloy film is demonstrated.

<Sputtering target for forming an Ag alloy film>
As dissolution raw materials, Ag having a purity of 99.9% by mass or more and Sb, Ca having a purity of 99.9% by mass or more were prepared and weighed so as to have a predetermined composition shown in Table 1.
Next, using a melting furnace, Ag was melted in a high vacuum or an inert gas atmosphere, and Sb and Ca were added to the obtained molten Ag and dissolved in a vacuum or an inert gas atmosphere. Then, it poured into the casting_mold | template and manufactured the ingot of the composition shown in Table 1. More specifically, when Ag was dissolved, the atmosphere was once evacuated (5 × 10 ⁻² Pa or less) and then replaced with Ar gas. Sb and Ca were added in an Ar gas atmosphere. Note that Ca is preferably added in the form of an AgCa alloy prepared in advance from the viewpoint of the uniformity of the alloy and the control of a small amount of Ca.

Next, the obtained ingot was cold-rolled at a reduction rate of 70% to obtain a plate material, and then heat treatment was performed at 600 ° C. for 2 hours in the air. And the sputtering target of the composition of Examples 1-9 of this invention and the composition of Comparative Examples 1-4 which has a diameter of 152.4 mm and a thickness of 6 mm was produced by implementing machining.
In addition, as a conventional example, a sputtering target having the same dimensions as described above and made of pure Ag (purity 99.9% by mass or more) was prepared.

The surface roughness of the above-mentioned sputtering target was measured at a measurement length of 10 mm using a surface roughness meter (manufactured by Mitsutoyo) so that the processing direction of the target was perpendicular to the measurement direction.
The measurement results are shown in Table 1.

<Ag alloy film>
Using the sputtering targets of Invention Examples 1 to 9 and Comparative Examples 1 to 4 described above, an Ag alloy film was formed under the following conditions.
The sputtering targets of Invention Examples 1 to 9 and Comparative Examples 1 to 4 described above are soldered to an oxygen-free copper backing plate using indium solder to form a target composite, which is mounted on a sputtering apparatus, and glass Sputtering was performed on the surface of the glass substrate with a distance from the substrate (Corning Eagle XG): 70 mm, power: DC 250 W, ultimate vacuum: 5 × 10 ⁻⁵ Pa, Ar gas pressure: 0.67 Pa An Ag alloy film having a thickness of 100 nm was formed.
Note that the above-described conventional sputtering target is soldered to an oxygen-free copper backing plate using indium solder to form a target composite, which is then mounted on a sputtering apparatus, and is mounted on a glass substrate under the same conditions as described above. An Ag film having a thickness of 100 nm was formed.

<Number of abnormal discharge>
A target complex soldered with indium solder on the above oxygen-free copper backing plate is attached to a normal magnetron sputtering apparatus, and after evacuating to 1 × 10 ⁻⁴ Pa, Ar gas pressure: 0.5 Pa is charged. Sputtering was performed under the conditions of power: DC 1000 W and target substrate distance: 60 mm. The number of abnormal discharges during sputtering was measured as the number of abnormal discharges for 30 minutes from the start of discharge using the arc count function of a DC power source (RPDG-50A) manufactured by MKS Instruments. The measurement results are shown in Table 1.

<Measurement of reflectance>
The reflectivities of the Ag alloy film and the Ag film obtained as described above were measured using a spectrophotometer using light having a wavelength in the range of 800 nm to 400 nm. Table 2 shows the reflectance of light having wavelengths of 405 nm, 450 nm, and 550 nm.

<Measurement of specific resistance value>
The sheet resistance values of the Ag alloy film and the Ag film obtained as described above were measured by the four-probe method, and the specific resistance value was calculated. Table 2 shows the specific resistance values after film formation.

<Heat resistance test>
The above sample was heat-treated in the atmosphere at a temperature of 250 ° C. and a holding time of 1 hour.
The reflectance and specific resistance value of the Ag alloy film and Ag film after the heat treatment were measured by the same method as described above. The evaluation results are shown in Table 2.

In Comparative Example 1 in which the Sb content is less than the range of the present invention, the reflectance after heat treatment was greatly reduced in the formed Ag alloy films at all wavelengths of 405 nm, 450 nm, and 550 nm.
In Comparative Example 2 in which the content of Sb is larger than the range of the present invention, the specific resistance value after film formation was high in the formed Ag alloy film. In addition, the reflectivity after film formation was low at all wavelengths of 405 nm, 450 nm, and 550 nm.
In Comparative Example 3 in which the Ca content was less than the range of the present invention, the arithmetic average roughness of the target surface was 2.56 μm, and the ten-point average roughness was 16.64 μm, which was relatively large. For this reason, the number of abnormal discharges increased to 23, and the Ag alloy film could not be stably formed.
In Comparative Example 4 in which the Ca content was greater than the range of the present invention, rolling cracks occurred during the production of the sputtering target.
In the conventional example made of pure Ag, the arithmetic average roughness of the target surface was 5.71 μm, and the ten-point average roughness was as large as 36.72 μm. For this reason, the number of abnormal discharges was as large as 36, and the Ag film could not be stably formed. Further, in the formed Ag film, the reflectance after heat treatment was low at all wavelengths of 405 nm, 450 nm, and 550 nm.

  On the other hand, in Examples 1 to 6 of the present invention in which the contents of Sb and Ca are within the scope of the present invention, the arithmetic average roughness of the target surface is 1.04 μm or less, and the ten-point average roughness is 6. It was small at 31 μm or less. For this reason, the number of abnormal discharges was small, and the Ag alloy film could be stably formed. Further, the formed Ag alloy film had a low specific resistance value after the film formation, and the reflectance after the film formation was high at all wavelengths of 405 nm, 450 nm, and 550 nm. Furthermore, the reflectance did not deteriorate significantly even after the heat treatment.

  As described above, according to the example of the present invention, the number of occurrences of abnormal discharge can be reduced and the film can be stably formed, the specific resistance value after film formation is low, the reflectance is high, and the heat treatment is performed after heat treatment. It was also confirmed that it is possible to provide a sputtering target for forming an Ag alloy film that can form an Ag alloy film whose reflectivity does not greatly deteriorate.

Claims (3)

  Ag containing at least 0.01 atomic percent and not more than 3.00 atomic percent, Ca at least 0.01 atomic percent and not more than 0.15 atomic percent, the balance being composed of Ag and inevitable impurities Sputtering target for alloy film formation.   2. The sputtering target for forming an Ag alloy film according to claim 1, wherein the atomic ratio of Sb and Ca contained is Sb / Ca ≧ 1.0.   3. The sputtering target for forming an Ag alloy film according to claim 1, wherein the arithmetic average roughness of the sputtering surface is 1.0 μm or less and the ten-point average roughness is 6.0 μm or less.