JP5159963B1 - Silver alloy sputtering target for forming conductive film and method for producing the same - Google Patents

Abstract

A silver alloy sputtering target for forming a conductive film capable of further suppressing arc discharge and splash and a method for producing the same.
SOLUTION: Sn is contained in an amount of 0.1 to 1.5% by mass, the balance is composed of Ag and inevitable impurities, the average grain size of the crystal grains is 30 μm or more and less than 120 μm, and the grain size of the crystal grains Is a silver alloy sputtering target having a variation of 20% or less of the average particle size, and is produced by subjecting a molten cast ingot to a hot rolling step, a cooling step, and a machining step in this order. It includes finishing hot rolling with a rolling reduction per pass of 20 to 50% and a strain rate of 3 to 15 / sec at a temperature of 400 to 650 ° C. after the pass. Rapid cooling is performed at a cooling rate of 1000 ° C./min.
[Selection figure] None

Description

  The present invention relates to a silver alloy sputtering target for forming a conductive film such as a reflective electrode of an organic EL element or a wiring film of a touch panel, and a method for producing the same.

The organic EL element applies a voltage between the anode and the cathode formed on both sides of the organic EL light emitting layer, injects holes from the anode and electrons from the cathode into the organic EL film, and generates holes in the organic EL light emitting layer. It is a light-emitting element that uses the principle of light emission when electrons and electrons are combined, and has recently attracted much attention as a display device. There are a passive matrix system and an active matrix system for driving organic EL elements. This active matrix method can be switched at high speed by providing one or more thin film transistors per pixel, which is advantageous for high contrast ratio and high definition, and can drive the characteristics of organic EL elements. It is.
There are two types of light extraction methods: a bottom emission method that extracts light from the transparent substrate side, and a top emission method that extracts light from the opposite side of the substrate. A top emission method with a high aperture ratio increases the brightness. It is advantageous.

  The reflective electrode film in this top emission structure desirably has high reflectivity and high corrosion resistance in order to efficiently reflect light emitted from the organic EL layer. It is also desirable that the electrode has a low resistance. As such a material, an Ag alloy and an Al alloy are known. However, in order to obtain an organic EL element with higher luminance, the Ag alloy is excellent because of its high visible light reflectance. Here, a sputtering method is employed for forming the reflective electrode film on the organic EL element, and a silver alloy target is used (Patent Document 1).

By the way, with the enlargement of the glass substrate at the time of manufacturing the organic EL element, a large silver alloy target used for forming the reflective electrode film has been used. Here, when sputtering is performed with high power applied to a large target, a phenomenon called “splash” occurs due to abnormal discharge of the target, and the molten fine particles adhere to the substrate and become between the wiring and electrodes. There is a problem in that the yield of the organic EL element is reduced by short-circuiting. Since the reflective electrode layer of the top emission type organic EL element serves as a base layer of the organic light emitting layer, higher flatness is required, and splash must be further suppressed.
In order to solve such a problem, in Patent Document 2 and Patent Document 3, as the target becomes larger, the reflective electrode film for an organic EL element that can suppress splash even when large power is applied to the target. A silver alloy target and a manufacturing method thereof have been proposed.

International Publication No. 2002/077317 JP 2011-100719 A JP 2011-162876 A

The silver alloy target for forming a reflective electrode film described in Patent Document 2 and Patent Document 3 can suppress splash even when a large amount of electric power is applied. Thus, the number of arc discharges increases and the splash due to arc discharge tends to increase, and further improvement is required.
In addition to the reflective electrode film for organic EL elements, a silver alloy film has been studied for a conductive film such as a lead-out wiring of a touch panel. As such a wiring film, for example, when pure Ag is used, migration occurs and a short circuit failure is likely to occur. Therefore, adoption of a silver alloy film has been studied.

  This invention is made | formed in view of such a situation, and it aims at providing the silver alloy sputtering target for electroconductive film formation which can suppress arc discharge and a splash further, and its manufacturing method.

As a result of intensive studies, the inventors of the present invention have further refined crystal grains to an average grain size of less than 120 μm in order to suppress an increase in the number of arc discharges associated with target consumption in a silver alloy target containing Sn, It was found that it is effective to suppress the variation to 20% or less of the average particle diameter.
Under such knowledge, the silver alloy sputtering target for forming a conductive film of the present invention contains 0.1 to 1.5% by mass of Sn, which is an element dissolved in Ag, with the balance being composed of Ag and inevitable impurities. A silver alloy sputtering target having an average particle diameter of the alloy of 30 μm or more and less than 120 μm, and a variation in the particle diameter of the crystal grains is 20% or less of the average particle diameter To do.

Sn dissolves in Ag, suppresses the growth of target crystal grains, and is effective in refining crystal grains. Since the hardness of the target is improved, warpage during machining is suppressed. Improve the corrosion resistance and heat resistance of the film formed by sputtering. If the amount is less than 0.1% by mass, the above effect cannot be obtained. If the amount exceeds 1.5% by mass, the reflectivity and electric resistance of the film decrease.
The reason why the average particle size is 30 μm or more and less than 120 μm is that if it is less than 30 μm, it is not practical and causes an increase in manufacturing cost. This is because it becomes prominent.
If the variation in average particle diameter exceeds 20%, the tendency of abnormal discharge to increase with the consumption of the target during sputtering becomes significant.

The silver alloy sputtering target for forming a conductive film of the present invention contains 0.1 to 1.5% by mass of Sn, which is an element that dissolves in Ag, and further includes Sb and Ga that are elements that dissolve in Ag. A silver alloy sputtering target containing at least one type of 0.1 to 2.5% by mass in total, with the balance being composed of Ag and inevitable impurities, the average grain size of the alloy crystal grains being 30 μm The crystal grain size variation is 20% or less of the average grain size.

  Sb and Ga have the effect of dissolving in Ag and further suppressing crystal grain growth. Corrosion resistance and heat resistance of the film formed by sputtering are further improved. In particular, Ga improves the chloride resistance of the film. When the content is less than 0.1% by mass, the above effect cannot be obtained. When the content exceeds 2.5% by mass, not only the reflectance and electrical resistance of the film are lowered, but also cracking occurs during hot rolling. The tendency to occur appears.

  The method for producing a silver alloy sputtering target for forming a conductive film according to the present invention includes a hot-melted ingot containing 0.1 to 1.5% by mass of Sn and the balance being composed of Ag and inevitable impurities. A method of manufacturing a silver alloy sputtering target by performing a rolling process, a cooling process, and a machining process in this order, wherein the hot rolling process has a reduction rate of 20 to 50% per pass and a strain rate. It includes 3 to 15 / sec of finish hot rolling at a temperature of 400 to 650 ° C. after the pass, and the cooling step is rapidly cooled at a cooling rate of 200 to 1000 ° C./min. To do.

  In addition, it contains 0.1 to 1.5% by mass of Sn, further contains at least one of Sb and Ga in a total amount of 0.1 to 2.5% by mass, and the balance is composed of Ag and inevitable impurities. A hot-rolling step, a cooling step, and a machining step are performed in this order to produce a silver alloy sputtering target, wherein the hot-rolling step is a reduction per pass. The temperature after the pass of finishing hot rolling with a rate of 20 to 50% and a strain rate of 3 to 15 / sec is included at least 1 pass at 400 to 650 ° C., and the cooling step is performed at 200 to 1000 ° C./min. It is characterized by rapid cooling at a cooling rate.

The reduction rate per pass of the finish hot rolling is set to 20 to 50% because if the reduction rate is less than 20%, the crystal grains are insufficiently refined, and rolling is attempted to obtain a reduction rate of 50% or more. This is because the load on the machine is excessive and not realistic.
Also, the strain rate was set to 3 to 15 / sec because if the strain rate is less than 3 / sec, the crystal grains are not sufficiently refined and a mixture of fine grains and coarse grains tends to appear. This is because a strain rate exceeding 15 / sec is not realistic because the load of the rolling mill is excessive.
If the temperature after each pass is less than 400 ° C., dynamic recrystallization becomes insufficient, and the tendency of variation in crystal grain size becomes remarkable. When it exceeds 650 ° C., crystal grain growth proceeds and the average crystal grain size becomes 120 μm or more.
And by rapidly cooling after this hot rolling, the growth of crystal grains can be suppressed and a fine crystal grain target can be obtained. When the cooling rate is less than 200 ° C./min, the effect of suppressing the growth of crystal grains is poor. Even if it exceeds 1000 ° C./min, it does not contribute to further miniaturization.

  According to the present invention, a target capable of further suppressing arc discharge and splash even when high power is applied during sputtering is obtained. By sputtering this target, the reflectance is high and the durability is excellent. A conductive film having properties can be obtained.

  Hereinafter, an embodiment of a silver alloy sputtering target for forming a conductive film and a method for producing the same of the present invention will be described. Unless otherwise indicated, “%” means “% by mass” unless otherwise specified.

In this target, the target surface (surface on the side subjected to sputtering of the target) has an area of 0.25 m ² or more, and in the case of a rectangular target, at least one side is 500 mm or more, and the upper limit of the length Is preferably 3000 mm from the viewpoint of target handling. On the other hand, the upper limit of the width is preferably 1700 mm from the viewpoint of the upper limit of the size that can be generally rolled by a rolling mill used in the hot rolling process. Further, from the viewpoint of target replacement frequency, the thickness of the target is preferably 6 mm or more, and from the viewpoint of discharge stability of magnetron sputtering, it is preferably 25 mm or less.

  The silver alloy sputtering target for forming a conductive film according to the first embodiment is composed of a silver alloy having a component composition containing 0.1 to 1.5% by mass of Sn and the balance of Ag and inevitable impurities, and the alloy. The average grain size of the crystal grains is 30 μm or more and less than 120 μm, and the grain size variation of the crystal grains is 20% or less of the average grain size.

  Ag has an effect of giving high reflectivity and low resistance to the reflective electrode film of the organic EL element and the wiring film of the touch panel formed by sputtering.

Since Sn improves the hardness of the target, it suppresses warpage during machining. In particular, warping during machining of a large target having a target surface with an area of 0.25 m ² or more can be suppressed. In addition, Sn has an effect of improving the corrosion resistance and heat resistance of the reflective electrode film of the organic EL element formed by sputtering. This is because Sn refines the crystal grains in the film and reduces the surface roughness of the film, and also increases the strength of the crystal grains by solid solution in Ag and suppresses the coarsening of the crystal grains due to heat. This is because it has an effect of suppressing an increase in the surface roughness of the film or suppressing a decrease in reflectance due to the corrosion of the film. Therefore, in the reflective electrode film or the wiring film formed using this silver alloy sputtering target for forming a conductive film, the corrosion resistance and heat resistance of the film are improved. Contributes to improving reliability in
The reason for limiting the content of Sn to the above range is that if the content is less than 0.1% by mass, the effect of adding Sn described above cannot be obtained, and if the content exceeds 1.5% by mass, This is because the electrical resistance is increased, and the reflectance and corrosion resistance of the film formed by sputtering are lowered, which is not preferable. Therefore, since the composition of the film depends on the target composition, the content of Sn contained in the silver alloy sputtering target is set to 0.1 to 1.5% by mass. More preferably, it is 0.2-1.0 mass%.

  The silver alloy sputtering target for forming a conductive film according to the second embodiment contains 0.1 to 1.5% by mass of Sn, and further 0.1 to 2.5% by mass of one or more of Sb and Ga. %, And the balance is composed of a silver alloy having a component composition composed of Ag and inevitable impurities, the average grain size of the alloy is 30 μm or more and less than 120 μm, and the variation in the grain size of the crystal grains is the average grain It is 20% or less of the diameter.

In the second embodiment, Sb and Ga have an effect of solid solution in Ag and further suppressing crystal grain growth. Corrosion resistance and heat resistance of the film formed by sputtering are further improved. In particular, Ga improves the chloride resistance of the film. When a film formed by sputtering is used as the lead wiring film of the touch panel, the touch panel is operated by touching with a finger, and therefore the wiring film needs to be resistant to the chlorine component contained in sweat from the human body. By adding, it becomes excellent in chloride resistance.
When the content of these Sb and Ga is less than 0.1% by mass, the above effect cannot be obtained. When the content exceeds 2.5% by mass, not only the reflectivity and electric resistance of the film are lowered, but also hot rolling. In this case, there is a tendency to crack.

  In the embodiment of each composition described above, the average particle diameter of the silver alloy crystal grains in the silver alloy sputtering target is 30 μm or more and less than 120 μm. If the average grain size of the silver alloy crystal grains is less than 30 μm, it is not practical and causes an increase in manufacturing cost. In addition, it is difficult to produce uniform crystal grains, and the dispersion of the grain size becomes large. Abnormal discharge is likely to occur during high-power sputtering, and splash occurs. On the other hand, when the target is 120 μm or more, as the target is consumed by sputtering, the unevenness of the sputtering surface increases due to the difference in the sputtering rate due to the difference in crystal orientation of each crystal grain. Abnormal discharge is likely to occur during sputtering, and splash is likely to occur.

Here, the average particle diameter of the silver alloy crystal grains is measured as follows.
A rectangular parallelepiped sample having a side of about 10 mm is collected from 16 points evenly within the sputtering surface of the target. Specifically, the target is divided into 16 vertical 4 × horizontal 4 locations and collected from the central part of each part. In the present embodiment, since a large target having a sputter surface of 500 × 500 (mm) or more, that is, a target surface having an area of 0.25 m ² or more is taken into consideration, a rectangular target generally used as a large target is used. The method for collecting the sample was described, but the present invention naturally exhibits the effect of suppressing the splash generation of the round target. At this time, according to the method of collecting a sample with a large rectangular target, the sample is equally divided into 16 places on the sputtering surface of the target and collected.
Next, the sputter surface side of each sample piece is polished. At this time, after polishing with water resistant paper of # 180 to # 4000, buffing is performed with abrasive grains of 3 μm to 1 μm.
Furthermore, etching is performed to such an extent that the grain boundary can be seen with an optical microscope. Here, a mixed liquid of hydrogen peroxide water and ammonia water is used as an etching solution, and the mixture is immersed for 1 to 2 seconds at room temperature to reveal grain boundaries. Next, a photograph with a magnification of 60 times or 120 times is taken with an optical microscope for each sample. The magnification of the photograph is selected so that the crystal grains can be easily counted.
In each photograph, a total of four 60 mm line segments are drawn vertically and horizontally at intervals of 20 mm in the shape of a blister, and the number of crystal grains cut along each straight line is counted. The number of crystal grains at the end of the line segment is counted as 0.5. Average section length: L (μm) is determined by L = 60000 / (M · N) (where M is an actual magnification and N is an average value of the number of crystal grains cut).
Next, from the obtained average section length: L (μm), the average particle diameter of the sample: d (μm) is calculated by d = (3/2) · L.
Thus, let the average value of the average particle diameter of the sample sampled from 16 places be the average particle diameter of the silver alloy crystal grains of the target.

When the variation in the grain diameter of the silver alloy crystal grains is 20% or less of the average grain diameter of the silver alloy crystal grains, splash during sputtering can be more reliably suppressed. Here, the dispersion of the particle size is the absolute value of deviation from the average particle size among the 16 average particle sizes obtained at 16 locations (| [(average particle size of one certain location) − (16 locations). Is determined as follows using the specified average particle size (specific average particle size).
| [(Specific average particle size) − (Average particle size at 16 locations)] | / (Average particle size at 16 locations) × 100 (%)

Next, the manufacturing method of the silver alloy sputtering target for conductive film formation of this embodiment is demonstrated.
The silver alloy sputtering target for forming a conductive film according to the first embodiment uses Ag of purity: 99.99% by mass or more and Sn of purity: 99.9% by mass or more as raw materials.
First, Ag is melted in a high vacuum or an inert gas atmosphere, Sn having a predetermined content is added to the resulting molten metal, and then melted in a vacuum or an inert gas atmosphere, Sn: 0.1 A melting cast ingot of a silver alloy containing ˜1.5 mass% and the balance being made of Ag and inevitable impurities is produced.
Here, melting of Ag is performed in an atmosphere in which the atmosphere is once evacuated and then replaced with argon, and adding Sn to the molten Ag in the argon atmosphere after melting stabilizes the composition ratio of Ag and Sn. From the standpoint of

  Further, in the silver alloy sputtering target for forming a conductive film of the second embodiment, the purity is 99.99% by mass or more of Ag, and the purity is 99.9% by mass or more of Sn, Sb, Ga. One or more of Sn: 0.1 to 1.5% by mass and Sb and Ga are added to the molten metal in a total amount of 0.1 to 3.0% by mass. Also in that case, Ag is melted in a high vacuum or an inert gas atmosphere, Sn, Sb, and Ga of a predetermined content are added to the obtained molten metal, and then melted in a vacuum or an inert gas atmosphere.

In addition, it is desirable to perform the above melting and casting in a vacuum or in an atmosphere of inert gas replacement, but it is also possible to use an atmospheric melting furnace, and when using an atmospheric melting furnace, It is melted and cast while spraying an inert gas or covering the surface of the molten metal with a carbon-based solid sealing material such as charcoal. Thereby, the content of oxygen and nonmetallic inclusions in the ingot can be reduced.
The melting furnace is preferably an induction heating furnace in order to make the components uniform.
Further, it is efficient and desirable to obtain a rectangular parallelepiped ingot by casting with a rectangular mold, but it is also possible to obtain a roughly rectangular ingot by processing a cylindrical ingot cast on a round mold.

The obtained rectangular parallelepiped ingot is heated and hot-rolled to a predetermined thickness, and then rapidly cooled.
In this case, the condition of the final hot rolling in the final stage of hot rolling is important. By appropriately setting the final hot rolling conditions, it is possible to produce a silver alloy plate with fine and uniform crystal grains. it can.
Specifically, in finish hot rolling, the rolling reduction per pass is 20 to 50%, the strain rate is 3 to 15 / sec, and the rolling temperature after each rolling pass is 400 to 650 ° C. This finish hot rolling shall include one or more passes. The total rolling rate of the entire hot rolling is, for example, 70% or more.
Here, the finish hot rolling is a rolling pass that strongly influences the crystal grain size of the plate material after rolling, including the final rolling pass, and, if necessary, from the final rolling pass to the third pass. You may think. After this final rolling, rolling with a rolling reduction of 7% or less may be added in the rolling temperature range for adjusting the plate thickness.
Further, the strain rate ε (sec ⁻¹ ) is given by the following equation.

In the above formula, H ₀ : sheet thickness (mm) on the entry side with respect to the rolling roll, n: rolling roll rotation speed (rpm), R: rolling roll radius (mm), r: rolling reduction (%), r '= R / 100.
By setting the rolling reduction per pass to 20 to 50% and the strain rate to 3 to 15 / sec, it will be strongly processed with large energy at a relatively low temperature, thereby preventing the mixing of coarse crystal grains, By dynamic recrystallization, fine and uniform crystal grains as a whole can be generated. If the rolling reduction per pass is less than 20%, the refinement of crystal grains is insufficient, and if it is attempted to obtain a rolling reduction exceeding 50%, the load on the rolling mill becomes excessive, which is not realistic. On the other hand, if the strain rate is less than 3 / sec, the crystal grains are not sufficiently refined and a mixture of fine grains and coarse grains tends to appear. A strain rate exceeding 15 / sec is not realistic because the load of the rolling mill is excessive.

The rolling temperature after each pass is 400 to 650 ° C., which is a low temperature for hot rolling, to suppress the coarsening of crystal grains. When the rolling temperature is less than 400 ° C., dynamic recrystallization becomes insufficient, and the tendency of variation in crystal grain size becomes remarkable. When the temperature exceeds 650 ° C., crystal grain growth proceeds and the average crystal grain size exceeds 120 μm.
This final finish hot rolling is performed from one pass to multiple passes as necessary.
A more preferable range of finish hot rolling is a rolling reduction rate of 25 to 50% per pass, a strain rate of 5 to 15 / sec, and a rolling temperature of 500 to 600 ° C. after the pass. It is preferable to carry out the above.
Note that the rolling start temperature may not be 400 to 650 ° C., and the rolling start temperature and the pass schedule are set so that the temperature at the end of each pass in the final hot rolling at the final stage is 400 to 650 ° C.

  And after such a hot rolling process, it cools rapidly with the cooling rate of 200-1000 degrees C / min until it becomes the temperature of 200 degrees C or less from the temperature of 400-650 degreeC. By this rapid cooling, the growth of crystal grains can be suppressed, and a rolled plate having fine crystal grains can be obtained. When the cooling rate is less than 200 ° C./min, the effect of suppressing the growth of crystal grains is poor. Even if it exceeds 1000 ° C./min, it does not contribute to further miniaturization. As a method of rapid cooling, it is good to perform a water shower for about 1 minute.

  The rolled plate thus obtained is corrected by a correction press, a roller leveler or the like, and then finished to a desired dimension by machining such as milling or electric discharge machining. The arithmetic average surface roughness (Ra) of the sputtering surface of the finally obtained sputtering target is preferably 0.2 to 2 μm.

  The silver alloy sputtering target for forming a conductive film of the present embodiment thus obtained can suppress abnormal discharge and suppress the occurrence of splash even when a large electric power is applied during sputtering. By sputtering this target, a conductive film having high reflectivity and excellent durability can be obtained. Further, by performing sputtering using this silver alloy sputtering target for forming a conductive film, a conductive film having good corrosion resistance and heat resistance and having a lower electric resistance can be obtained. This is particularly effective when the target size is a large target having a width of 500 mm, a length of 500 mm, and a thickness of 6 mm or more.

Example 1
Ag having a purity of 99.99% by mass or more and Sn having a purity of 99.9% by mass or more were prepared as an additive material and loaded into a high-frequency induction melting furnace constructed with a graphite crucible. The total mass at the time of dissolution was about 1100 kg.
At the time of melting, Ag is first melted, and after Ag has melted down, an additional raw material is added so as to have the target composition shown in Table 1, and the molten alloy is sufficiently stirred by the stirring effect by induction heating, and then made of cast iron. Cast into a mold.
The shrinkage nest portion of the ingot obtained by this casting was excised, the surface that was in contact with the mold was removed, and a rectangular parallelepiped ingot having a rough dimension of 640 × 640 × 180 (mm) was obtained as a healthy portion.

The ingot was heated to 780 ° C., rolled in one direction and extended from 640 mm to 1700 mm, rotated 90 degrees, and further rolled in the other direction of 640 mm, approximately 1700 × 2200. It was set as the board | plate material of a dimension of * 19 (mm).
This hot rolling was repeated a total of 12 passes. Among them, the conditions of the pass from the final pass to the third pass (strain rate per pass, rolling reduction, plate material temperature after pass) are as shown in Table 1. The total rolling rate of the entire hot rolling was 90%.
After the hot rolling was completed, the rolled plate was cooled under the conditions shown in Table 1.
After cooling, the plate material was passed through a roller leveler to correct distortion caused by rapid cooling, and machined to a size of 1600 × 2000 × 15 (mm) to obtain a target.

(Examples 2 to 10, Comparative Examples 1 to 10)
In the same manner as in Example 1, the heating temperature of the ingot before hot rolling is 510 to 880 ° C., the plate thickness after final rolling is 9.5 to 25.6 mm, the total number of passes is 11 to 14, and the total rolling rate Was varied in the range of 86 to 95%, and the target was produced under the conditions of the target composition shown in Table 1, the conditions of the pass from the final pass to the third pass, and the cooling rate after hot rolling. In Table 1, the cooling rate is indicated by cooling with a water shower, and no water cooling is simply allowed to cool. However, the thickness of the target after machining was in the range of 6 to 21 mm.

(Examples 11 to 13, Comparative Example 11)
It melt-casts in the same manner as in Example 1 to produce an ingot having an approximate size of 640 × 640 × 60 (mm), this ingot is heated to 680 ° C., and then hot-rolled to approximately 1200 × 1300 × 15. It was set as the board | plate material of the dimension of (mm).
This hot rolling was repeated a total of 6 passes. Among them, the conditions of the pass from the final pass to the third pass (strain rate per pass, rolling reduction, plate material temperature after pass) are as shown in Table 1. The total rolling rate of the entire hot rolling was 75%.
After the hot rolling was completed, the rolled plate was cooled under the conditions shown in Table 1.
After cooling, the plate material was passed through a roller leveler to correct distortion caused by rapid cooling, and machined to a size of 1000 × 1200 × 12 (mm) to obtain a target.

(Examples 14 to 21, Comparative Examples 12 to 14)
Ag having a purity of 99.99% by mass or more and Sn, Sb, Ga having a purity of 99.9% by mass or more are prepared as additive materials, and Ag is first melted in a high-frequency induction melting furnace constructed with a graphite crucible. After the melted, the added raw materials were introduced so as to have the target composition shown in Table 1, and the molten alloy was sufficiently stirred by the stirring effect by induction heating, and then cast into a cast iron mold.
In Examples 14 to 21 and Comparative Examples 12 to 14, the ingots obtained by this casting had an approximate size of 640 × 640 × 60 (mm) in the same manner as in Examples 11 to 13 and Comparative Example 11 described above. After producing an ingot and heating to 680 degreeC, it hot-rolled similarly to the above, and was set as the board | plate material of a dimension of about 1200x1300x15 (mm).
This hot rolling was repeated a total of 6 passes. Among them, the conditions of the pass from the last pass to the third pass (strain rate per pass, rolling reduction, plate material temperature after pass) were as shown in Table 1. The total rolling rate of the entire hot rolling was 75%. And after cooling on the conditions shown in Table 1, the board | plate material was passed through the roller leveler, the distortion | strain which arose by rapid cooling was corrected, and it machined to the dimension of 1000x1200x12 (mm), and set it as the target.

For the obtained target, the warpage after machining, the average particle diameter, and its variation are measured, and the number of abnormal discharges during sputtering is measured by attaching to a sputtering device. Roughness, reflectance, chloride resistance, and specific resistance were measured.
(1) Warpage after machining The amount of warpage per 1 m of the silver alloy sputtering target after machining was measured, and Table 2 shows the results.
(2) Average particle diameter, variation thereof The particle diameter measurement of the silver alloy crystal grains was carried out from the target manufactured as described above, and samples were equally distributed from 16 points as described in the embodiment for carrying out the invention. The average particle size of the surface as viewed from the sputter surface of each sample is measured, and the average particle size of the silver alloy crystal grains and the average particle size of the silver alloy crystal grains, which are the average value of the average particle diameter of each sample, are measured. Variation was calculated.

(3) Number of abnormal discharges during sputtering A disc having a diameter of 152.4 mm and a thickness of 6 mm was cut out from an arbitrary portion of the target manufactured as described above and soldered to a copper backing plate. Using this soldered target as a target for splash evaluation during sputtering, the number of abnormal discharges during sputtering was measured.
In this case, after attaching the soldered target to a normal magnetron sputtering apparatus and exhausting to 1 × 10 ⁻⁴ Pa, Ar gas pressure: 0.5 Pa, input power: DC 1000 W, target substrate distance: 60 mm, Sputtering was performed. The number of abnormal discharges for 30 minutes in the initial period of use, 4 hours of empty sputtering and replacement of the protection plate are repeated, and the target is consumed by intermittently sputtering for 20 hours, and then abnormal discharges for the subsequent 30 minutes. The number of times was measured. The number of abnormal discharges was measured by an arc count function of a DC power supply (model number: RPDG-50A) manufactured by MKS Instruments.

(4) Basic characteristic evaluation as a conductive film (4-1) Surface roughness of the film Sputtering was performed on the glass substrate of 20 × 20 (mm) under the same conditions as described above using the target for evaluation. A film having a thickness of 100 nm was formed to obtain a silver alloy film. Furthermore, in order to evaluate heat resistance, this silver alloy film was subjected to a heat treatment at 250 ° C. for 10 minutes, and then the average surface roughness (Ra) of the silver alloy film was measured by an atomic force microscope.
(4-2) Reflectance The absolute reflectance at a wavelength of 550 nm of a silver alloy film formed in the same manner as described above on a 30 × 30 (mm) glass substrate was measured with a spectrophotometer.
Further, for the evaluation of corrosion resistance, the spectrophotometer after holding the absolute reflectance at a wavelength of 550 nm of the silver alloy film formed in the same manner as described above for 100 hours in a constant temperature and high humidity bath at a temperature of 80 ° C. and a humidity of 85%. Measured by.
(4-3) Chlorination resistance In order to confirm the effect of Ga addition, a silver alloy film formed in the same manner as described above using a Ga-added target (Examples 19 to 23, Comparative Examples 10 and 11). A 5% by weight NaCl aqueous solution was sprayed on the membrane surface. Spraying was performed in a direction parallel to the film surface from a position of 20 cm in height from the film surface and a distance of 10 cm from the edge of the substrate, so that the NaCl aqueous solution sprayed on the film fell as freely as possible and adhered to the film. After spraying 5 times every minute, rinsing with pure water was repeated 3 times, and dry air was sprayed to blow off moisture and dry.
After spraying the salt water, the surface of the silver alloy film was visually observed to evaluate the surface state. As the evaluation criteria for chloride resistance, those with white turbidity or spots that cannot be confirmed or only partially confirmed are judged as “good”, and those with white turbidity or spots confirmed on the entire surface are judged as “bad” with two stages. The surface condition was evaluated. Since the target to which Ga was not added was not evaluated, it was written as “−”.
(4-4) Specific resistance of film The specific resistance of the silver alloy film formed in the same manner as described above was measured.
These evaluation results are shown in Table 2.

In the target material of the example, the average grain diameter of the silver alloy crystal grains is in the range of 30 μm or more and less than 120 μm, and the variation in the grain diameter of the silver alloy crystal grains is within 20% of the average grain diameter of the silver alloy crystal grains. there were. The warpage after machining was small, and the number of abnormal discharges during sputtering was small not only at the beginning of use but also after consumption. In addition, in the case of adding Sb and Ga, the average crystal grain size tends to be small, and the number of abnormal discharges is as small as 1 or less. However, when the amount of addition was too large (over 2.5% by mass in total), cracking occurred during finish hot rolling, and the warpage could not be measured.
In addition, the conductive film obtained from the target material of the example was excellent in reflectance and specific resistance, and the surface roughness was as small as 2 μm or less.
In addition, it can be seen that the conductive film obtained from the Ga-added target has excellent chlorination resistance and is effective for a conductive film such as a touch panel.

  In addition, this invention is not limited to the said embodiment, A various change can be added in the range which does not deviate from the meaning of this invention.

Claims (4)

A silver alloy sputtering target containing 0.1 to 1.5% by mass of Sn, which is an element that dissolves in Ag , with the balance being a composition of Ag and inevitable impurities, the average grain size of the alloy crystal grains A silver alloy sputtering target for forming a conductive film, characterized in that the diameter is 30 μm or more and less than 120 μm, and the variation in the grain size of the crystal grains is 20% or less of the average grain size. 0.1 to 1.5% by mass of Sn, which is an element that dissolves in Ag, and 0.1 to 2.5 mass in total of one or more of Sb and Ga that are an element that dissolves in Ag %, And the balance is a silver alloy sputtering target having a component composition consisting of Ag and inevitable impurities, the average grain size of the alloy grains is 30 μm or more and less than 120 μm, and the grain size variation of the crystal grains Is a silver alloy sputtering target for forming a conductive film, characterized by being 20% or less of the average particle size.   By applying a hot rolling step, a cooling step, and a machining step in this order to a molten cast ingot containing 0.1 to 1.5% by mass of Sn and the balance being composed of Ag and inevitable impurities, silver is obtained. A method of manufacturing an alloy sputtering target, wherein the hot rolling step is performed after finishing hot rolling with a rolling reduction rate of 20 to 50% per pass and a strain rate of 3 to 15 / sec. The manufacturing method of the silver alloy sputtering target for conductive film formation characterized by including 1 pass or more at -650 degreeC, and the said cooling process quenches rapidly with the cooling rate of 200-1000 degreeC / min.   It contains 0.1 to 1.5% by mass of Sn, further contains at least one of Sb and Ga in a total amount of 0.1 to 2.5% by mass, and the balance is composed of Ag and inevitable impurities. The molten cast ingot is subjected to a hot rolling step, a cooling step, and a machining step in this order to produce a silver alloy sputtering target, wherein the hot rolling step has a reduction rate per pass. It includes 20 to 50% finish hot rolling with a strain rate of 3 to 15 / sec and the temperature after the pass includes one pass or more at 400 to 650 ° C., and the cooling step is a cooling rate of 200 to 1000 ° C./min. A method for producing a silver alloy sputtering target for forming a conductive film, characterized in that the method is rapidly cooled at a low temperature.