TWI576442B - Ag alloy sputtering target for forming conductive film and method of manufacturing the same - Google Patents

Description

Silver alloy sputtering target for forming conductive film and manufacturing method thereof

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

The priority of the present application is based on Japanese Patent Application No. 2013-048388, filed on Jan.

The organic EL element is a light-emitting element using a principle in which a voltage is applied between an anode and a cathode formed on both sides of the organic EL light-emitting layer, and electrons are injected from the anode into the organic EL film from the cathode. The light is emitted when the hole and the electron are combined in the organic EL light-emitting layer; it has been attracting attention in recent years in terms of display device use. The driving method of the organic EL element includes a passive matrix method and an active matrix method. In the active matrix method, one or more thin film transistors are provided on one pixel, thereby enabling high-speed switching, which is advantageous for high contrast and high definition, and is capable of It is possible to drive the characteristics of organic EL components.

Further, the light extraction method includes a bottom emission method in which light is emitted from the transparent substrate side and a top emission method in which light is taken out from the opposite side of the substrate, and an upper light emission method having a higher aperture ratio is used. Conducive to high brightness.

The reflective electrode film in the upper illuminating structure, in order to be efficient The light that is emitted by the organic EL layer is reflected by the ground, and is preferably high in reflectance and high in corrosion resistance. Further, as the electrode, it is desirable to have a low resistance. Although Ag alloy and Al alloy are conventionally used for such a material, in order to obtain an organic EL element having higher brightness, the Ag alloy is superior in that its visible light reflectance is high. Here, when a reflective electrode film for an organic EL element is formed, a sputtering method is used, and a silver alloy target is used (Patent Document 1).

However, with the increase in the size of the glass substrate during the production of the organic EL element, a large-sized object is gradually used as the silver alloy target used for forming the reflective electrode film. Here, when high-power is applied to the large-sized target for sputtering, there is a problem that a phenomenon called "splash" occurs due to abnormal discharge of the target, and the molten fine particles adhere to the substrate. The wiring or the short circuit between the electrodes causes a decrease in the yield of the organic EL element. In the reflective electrode layer of the organic light-emitting device of the upper light-emitting type, since the reflective electrode layer is the underlying layer of the organic light-emitting layer, higher flatness is required, and splashing must be suppressed.

In order to solve such a problem, Patent Literature 2 and Patent Document 3 propose a silver alloy target for forming a reflective electrode film of an organic EL device, and a method for producing the same, which is accompanied by an increase in the size of the target, even if a large power is supplied to the target. Can suppress splashes.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] International Publication No. 2002/077317

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-100719

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-162876

The silver alloy target for forming a reflective electrode film described in the above-mentioned Patent Document 2 and Patent Document 3 can suppress spatter even when a large amount of electric power is input, but the arc discharge (arc) accompanying the consumption of the target in the large-sized silver alloy target. The number of discharges increases, and the spatter caused by the arc discharge tends to increase, and further improvement is required.

In addition to the reflective electrode film for an organic EL device, it is also being studied whether a silver alloy film can be used for a conductive film such as a pull-out wiring of a touch panel. In such a wiring film, for example, if pure Ag is used, migration occurs and short-circuit defects are likely to occur. Therefore, a silver alloy film has been proposed.

The present invention has been made in view of the above circumstances, and an object of the invention is to provide a silver alloy sputtering target for forming a conductive film capable of further suppressing arc discharge and splashing, and a method for producing the same.

The focus of the research by the team of the present invention has led to the finding that, in order to further suppress the increase in the number of arc discharges associated with the consumption of the target, it is effective to refine the crystal grains to an average particle diameter of less than 30 μm, and The heterogeneity of the crystal grain size is suppressed to 30% or less of the average particle diameter.

Based on this finding, the silver alloy sputtering target for forming a conductive film of the present invention is a silver alloy sputtering target having the following composition, that is, containing an element which is solid-solubilized in Ag, that is, In and Sn. The total amount of one or more is 0.1 to 1.5% by mass, and the remainder is composed of Ag and unavoidable impurities, and the average grain size of the crystal grains of the alloy is 1 μm or more and less than 30 μm, and the grain size of the crystal grains is The heterogeneity is 30% or less of the average particle diameter.

In has an effect of suppressing grain growth of a solid solution-soluble target and refining crystal grains. In will increase the hardness of the target, so it will suppress warpage during machining. In will improve the corrosion resistance and heat resistance of the film formed by sputtering.

Sn, like In, has an effect of suppressing grain growth of a solid solution-soluble target and refining crystal grains. Sn raises the hardness of the target, so it suppresses warpage during machining. Sn enhances the corrosion resistance and heat resistance of the film formed by sputtering.

When the total content of one or more of In and Sn is less than 0.1% by mass, the above effect cannot be obtained, and when it exceeds 1.5% by mass, the reflectance or electric resistance of the film is lowered.

The reason why the average particle diameter is set to 1 μm or more and less than 30 μm is that if the thickness is less than 1 μm, the manufacturing cost is unrealistic, and if it is 30 μm or more, it becomes difficult to control the unevenness of the crystal grain size. As a result, the target is consumed at the time of sputtering, and the tendency of abnormal discharge to increase becomes remarkable.

When the heterogeneity of the average particle diameter exceeds 30%, the target material is consumed during sputtering, and the tendency of abnormal discharge increases.

The silver alloy sputtering target for forming a conductive film of the present invention is a silver alloy sputtering target having the following composition, that is, a total of one or more of In and Sn which are elements which are solid-solubilized in Ag, that is, In the range of 0.1 to 1.5% by mass, one or more of the elements containing Sb and Ga which are solid-dissolved in Ag are 0.1 to 2.5% by mass in total, and the remainder is composed of Ag and unavoidable impurities. The average grain size of the crystal grains of the alloy is 1 μm or more and less than 30 μm, and the unevenness of the particle diameter of the crystal grains is 30% or less of the average particle diameter.

Sb and Ga are solid-solubilized in Ag and have an effect of further suppressing grain growth. Sb and Ga will further improve the corrosion resistance and heat resistance of the film formed by sputtering. In particular, Ga will increase the chlorination 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 or electric resistance of the film is lowered, but also the hot press delay tends to cause cracking.

In addition, the method for producing a silver alloy sputtering target for forming a conductive film of the present invention has a composition of 0.1 to 1.5% by mass in total of one or more of In and Sn, and the remainder is Melting and casting ingots composed of Ag and inevitable impurities, sequentially applied A method for manufacturing a silver alloy sputtering target by a hot rolling process, a cooling process, a cold rolling process, a heat treatment process, a mechanical processing project, wherein the hot rolling process includes more than one pass heat Calendering, the rolling reduction rate per pass of the finish hot rolling is 20 to 35%, the strain rate is 3 to 10/sec, and the temperature after the pass is 400 to 650 ° C; in the aforementioned cooling engineering, Rapid cooling to a temperature below 200 ° C at a cooling rate of 100 to 1000 ° C / min; in the cold rolling process, the average reduction rate per pass is 10 to 30% of the total calendering pass, and the strain rate is at full calendering. The average value of the pass is 3 to 10/sec, and the total reduction ratio is 40 to 80% until the target thickness is reached. In the heat treatment process, the temperature is maintained at 350 to 550 ° C for 1 to 2 hours.

In addition, a silver alloy sputtering target for forming a conductive film In the method of the present invention, the total amount of one or more of In and Sn is 0.1 to 1.5% by mass, and the total of one or more of Sb and Ga is 0.1 to 2.5% by mass. The remaining part is a molten cast ingot composed of Ag and unavoidable impurities, and is sequentially subjected to hot rolling engineering, cooling engineering, cold rolling engineering, heat treatment engineering, mechanical processing engineering, thereby manufacturing a silver alloy sputtering target material. The hot rolling process includes the finishing hot rolling of more than one pass, and the rolling reduction rate per pass of the finishing hot rolling is 20 to 35%, and the strain rate is 3 to 10/ Sec, and the temperature after the pass is 400~650 °C; in the above cooling project, it is rapidly cooled to below 200 °C with a cooling rate of 100~1000 °C/min; in the cold rolling project, every one pass is pressed. The average value of the full calendering pass is 10~30%, and the strain rate is in the full calendering pass. The average value is 3 to 10/sec, and the total reduction ratio is 40 to 80% until the target thickness is reached. In the heat treatment process, the temperature is maintained at 350 to 550 ° C for 1 to 2 hours.

The reduction rate of each pass of the finish hot rolling is set to 20~ The reason for 35% is that if the reduction ratio is less than 20%, the grain refinement becomes insufficient. If a reduction ratio of more than 35% is desired, the load load of the calender becomes too large to be practical. .

Further, the reason why the strain rate is set to 3 to 10/sec is that if the strain rate is less than 3/sec, the grain refinement becomes insufficient, and the tendency of the fine particles and the coarse particles to be mixed appears. However, if the strain rate exceeds 10/sec, the load load of the calender becomes too large to be practical.

If the temperature after each pass is less than 400 ° C, the dynamic recrystallization is insufficient, and the tendency of the grain size unevenness to increase becomes remarkable. When it exceeds 650 ° C, grain growth progresses, and the grain refinement cannot be achieved.

Further, after the hot rolling, the grain growth is suppressed by rapid cooling, and a target of fine crystal grains can be obtained. If the cooling rate is less than 100 ° C / min, the grain growth progresses, which is not preferable. Even if it exceeds 1000 ° C / min, it does not contribute to further miniaturization.

The reason why the rolling reduction rate per one pass of the cold rolling is set to 10 to 30% in the average value of the total rolling pass is that if the film is less than 10%, the grain refinement is insufficient, and the particle size is insufficient. The heterogeneity also increases and is not ideal, and if a reduction ratio of more than 30% is desired, the load load of the calender becomes too large to be practical. The reason why the calendering strain rate of the cold rolling is set to 3 to 10/sec as the average value of the total calendering pass is that the grain refinement is less than 3/sec. If it becomes insufficient, the tendency of the fine particles and the coarse particles to be mixed appears, and if the strain rate exceeds 10/sec, the load load of the calender becomes too large to be practical.

The reason why the total reduction ratio of cold rolling is set to 40 to 80% is that if the temperature is less than 40%, the strain energy imparted by cold rolling is insufficient, and it is difficult to refine the crystal grains by recrystallization. It is uniform, and if it exceeds 80%, it is difficult to design a hot rolling which satisfies the rolling reduction ratio of hot rolling of 20% or more and the strain rate of 3 to 10/sec.

In the heat treatment after cold rolling, if the temperature is less than 350 ° C or the time is less than 1 hour, the recrystallization will be insufficient, and the unevenness of the particle diameter will increase. If the temperature exceeds 550 ° C or the time exceeds 2 hours, the grain growth progresses and the average grain size exceeds 30 μm.

According to the present invention, it is possible to obtain a target which can further suppress arc discharge and splash even when large electric power is input during sputtering, and by sputtering the target, conductivity with high reflectance and excellent durability can be obtained. membrane.

Hereinafter, an embodiment of the silver alloy sputtering target for forming a conductive film of the present invention and a method for producing the same will be described. In addition, % indicates the mass % except for the case where the percentage is simply indicated unless otherwise specified.

In the target, the surface of the target (the surface on the sputtering side 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 disposed from the target ( The viewpoint of handling) seems to be preferably 3000 mm. On the other hand, the upper limit of the width is preferably from 1700 mm from the viewpoint of the upper limit of the calenderability of the calender used in the hot rolling process. Further, the thickness of the target is preferably 6 mm or more from the viewpoint of the frequency of replacement of the target, and is preferably 25 mm or less from the viewpoint of discharge stability of magnetron sputtering.

Silver alloy sputtering for forming a conductive film according to the first embodiment The target material is composed of a silver alloy having the following composition, that is, a total of one or more of In and Sn which are elements which are solid-solubilized in Ag, is 0.1 to 1.5% by mass in total, and the remainder is Ag and inevitably It is composed of impurities; the average grain size of crystal grains of the alloy is 1 μm or more and less than 30 μm, and the grain size heterogeneity is 30% or less of the average particle diameter.

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

In will increase the hardness of the target, so it will suppress warpage during machining. In particular, it is possible to suppress warpage of a large target having an area of 0.25 m ² or more on the surface of the target during machining. Further, In 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 In has an effect of refining crystal grains in the film while reducing the surface roughness of the film, and further, increasing the strength of crystal grains solid-solubilized in Ag, and suppressing coarse grains due to heat. The surface roughness of the film is suppressed to be increased, or the reflectance is lowered due to film corrosion. Therefore, the conductive electrode is used to form a reflective electrode film or a wiring film formed by sputtering a target material with a silver alloy, which improves the corrosion resistance and heat resistance of the film, thereby contributing to the improvement of the luminance or the improvement of the organic EL element. Reliability of wiring such as touch panels.

Sn, like In, has an effect of suppressing grain growth of a solid solution-soluble target and refining crystal grains. Sn raises the hardness of the target, so it suppresses warpage during machining. Sn enhances the corrosion resistance and heat resistance of the film formed by sputtering.

If the total content of one or more of In and Sn is not When the content is 0.1% by mass or more, the effect of adding In and Sn described above cannot be obtained, and if it is more than 1.5% by mass, the electrical resistance of the film is increased, and the reflectance or corrosion resistance of the film formed by sputtering is rather lowered. It is not ideal. Therefore, since the composition of the film is related to the target composition, the total content of one or more of In and Sn contained in the silver alloy sputtering target is set to 0.1 to 1.5% by mass. More preferably, it is 0.2 to 1.0% by mass.

In addition, the silver alloy sputtering target for forming a conductive film of the second embodiment has a composition of 0.1 to 1.5 in total of one or more of elements containing solid solution of Ag, that is, In and Sn. In addition, one or more of the elements containing solid solution in Ag, that is, Sb and Ga, are 0.1 to 2.5% by mass in total, and the remainder is composed of Ag and unavoidable impurities; the average grain size of the alloy crystal grains When the thickness is 1 μm or more and less than 30 μm, the grain size heterogeneity is 30% or less of the average particle diameter.

In the second embodiment, Sb and Ga are solid-solubilized in Ag, and have an effect of further suppressing grain growth. Sb and Ga will be more enhanced to splash Corrosion resistance and heat resistance of the film formed by plating. In particular, Ga will increase the chlorination resistance of the film. When a film formed by sputtering is used as a pull-out wiring film of a touch panel, since the touch panel is touched by a finger, the wiring film must be resistant to chlorine contained in sweat from the human body. By adding Ga, the chlorination resistance becomes excellent.

When the total content of these Sb and Ga is less than 0.1% by mass, the above effect cannot be obtained, and if it exceeds 2.5% by mass, not only the reflectance or electric resistance of the film is lowered, but also the hot pressing delay tends to cause cracking. .

In the embodiment of the above composition, the silver alloy sputtering target The average grain size of the silver alloy crystal grains in the medium is 1 μm or more and less than 30 μm. If the average particle diameter of the silver alloy crystal grains is set to less than 1 μm, it is impractical to cause an increase in manufacturing cost. Further, it is difficult to produce uniform crystal grains, and the unevenness of particle diameter is increased. Therefore, abnormal discharge is likely to occur during sputtering of large electric power, and splashing occurs. On the other hand, when the average particle diameter is 30 μm or more, it becomes difficult to control the unevenness of the crystal grain size, and as a result, the target material is consumed by sputtering, and the crystal orientation of each crystal grain is different. The difference in sputtering rate causes the unevenness of the sputtering surface to increase, so that abnormal discharge is likely to occur during sputtering of large electric power, and splashing is likely to occur.

Here, the average particle diameter of the silver alloy crystal grains is measured in the following manner.

In the sputtering surface of the target, a rectangular parallelepiped sample of about 10 mm on each side was uniformly taken from 16 locations. Specifically, the target is divided into 16 positions of 4 in the vertical direction and 4 in the horizontal direction, and is taken from the central portion of each part. In addition, in the present embodiment, a sputtering target having a surface of 500 × 500 (mm) or more, that is, a large target having an area of 0.25 m ² or more on the surface of the target is used as a starting point. The method of taking a sample by using a rectangular target material is of course effective in suppressing splashing of a circular target. At this time, according to the method of taking the sample of the large rectangular target, it is divided into 16 places in the sputtering surface of the target and taken.

Next, the sputtering surface side of each sample piece was polished. At this time, after grinding with #180~#4000 water sandpaper, buffing was performed with 3 μm to 1 μm.

Further, it is etched to the extent that the grain boundaries can be seen by an optical microscope. Here, the etching liquid is a mixture of hydrogen peroxide water and ammonia water, and immersed at room temperature for 1 to 2 seconds to cause grain boundaries to appear. Next, for each sample, photographs having a magnification of 200 times, 500 times, or 1000 times were taken with an optical microscope. The magnification of the photo is chosen to easily count the magnification of the grain.

In each of the photographs, four 60 mm line segments were drawn in a grid shape at intervals of 20 mm, and the number of crystal grains cut by the respective straight lines was counted. In addition, the number of grains at the end of the line segment is counted as 0.5. Average slice length: L (μm) was determined by L = 60000 / (M.N) (where M is the substantial magnification and N is the average of the number of crystal grains to be cut).

Next, the average slice length obtained is: L (μm), with d = (3/2). L calculates the average particle diameter of the sample: d (μm).

In this manner, the average value of the average particle diameters of the samples sampled from 16 points was taken as the average particle diameter of the silver alloy crystal grains of the target.

When the unevenness of the particle diameter of the silver alloy crystal grains is 30% or less of the average particle diameter of the silver alloy crystal grains, the sputtering can be more reliably suppressed. Splash. Here, the heterogeneity of the particle diameter is the absolute value of the deviation from the average particle diameter among the 16 average particle diameters obtained at 16 (|[(an average particle diameter of one of the 16 places) - (average particle diameter at 16 points)]|) is the largest, and the average particle diameter (specific average particle diameter) found by the above is calculated as follows.

[(Specific average particle diameter) - (average particle diameter at 16)] | / (average particle diameter at 16) × 100 (%)

Next, a method of producing a silver alloy sputtering target for forming a conductive film according to the present embodiment will be described.

In the silver alloy sputtering target for forming a conductive film according to the first embodiment, Ag is used in a purity of 99.99% by mass or more, and In and Sn having a purity of 99.9% by mass or more.

First, Ag is melted in a high-vacuum or inert gas atmosphere, and one or more of In and Sn having a predetermined content is added to the obtained melt to make the total amount of 0.1 to 1.5% by mass. Thereafter, it is melted in a vacuum or an inert gas atmosphere to produce a melt-cast ingot containing one or more of In and Sn in an amount of 0.1 to 1.5% by mass, and the remaining portion is a silver alloy composed of Ag and unavoidable impurities.

Here, the melting of Ag is carried out in an environment where the environment is temporarily vacuumed and then replaced with argon. From the viewpoint of stabilizing the composition ratio of Ag to In and Sn, it is preferable to melt in an argon atmosphere. In and Sn are added to the melt of Ag.

Silver alloy sputtering for forming a conductive film according to the second embodiment In the target material, Ag, a purity of 99.99% by mass or more, and In, Sn, Sb, and Ga having a purity of 99.9% by mass or more are used, and one or more of In and Sn are added to the melt of Ag to make a total of In the range of 0.1 to 1.5% by mass, the total amount of one or more of Sb and Ga added is 0.1 to 2.5% by mass. In this case, Ag is similarly melted in a high vacuum or an inert gas atmosphere, and a predetermined content of In, Sn, Sb, and Ga is added to the obtained melt, and then melted in a vacuum or an inert gas atmosphere.

In addition, the above melting/casting is ideally in a vacuum or In an inert gas replacement environment, an atmospheric melting furnace can also be used. When an atmospheric melting furnace is used, an inert gas is sprayed onto the surface of the molten stone, or a carbon-based solid sealing material such as charcoal is used to cover the melting. The surface of the soup is melted and cast on one side. In this way, the content of oxygen or non-metallic inclusions in the ingot can be reduced.

The melting furnace is preferably an induction heating furnace to homogenize the components.

Further, in terms of efficiency, it is desirable to obtain a rectangular ingot by casting in a square mold, but it is also possible to process a cylindrical ingot cast in a circular mold to obtain a substantially rectangular ingot. .

The obtained rectangular parallelepiped ingot is heated, hot rolled to a predetermined thickness, and then rapidly cooled, and subjected to cold rolling and heat treatment.

In this case, it is important to perform the final hot rolling in the final stage of hot rolling and the cold rolling and heat treatment conditions after the rapid cooling. By appropriately setting these conditions, it is possible to produce a fine and uniform crystal grain of the silver alloy sheet. .

Specifically, in the finishing hot rolling, every one pass is pressed. The rate is set to 20~35%, the strain rate is set to 3~10/sec, and the calendering temperature after each rolling pass is set to 400~650°C. The hot calendering includes the finish hot rolling of 1 or more passes. The total rolling ratio of the entire hot rolling is set to, for example, 40% or more.

Here, the term "finished hot rolling" refers to a rolling pass that strongly affects the grain size of the rolled sheet material; and including the final rolling pass, it may be considered from the final rolling pass to the final rolling pass. The first two times.

Further, the strain rate ε (sec ^-1 ) is given by the following formula.

In the above formula, H ₀ : plate thickness (mm) for the entry side of the calender roll, n: calender roll rotation speed (rpm), R: calender roll radius (mm), r: reduction ratio (%), r' =r/100.

The reduction rate per pass is set to 20~35%, and the strain rate is set to 3~10/sec, so that it can be subjected to strong plastic deformation at a relatively low temperature, so that it can The coarse crystal grains are prevented from being mixed, and the fine and uniform crystal grains are formed by dynamic recrystallization. If the reduction ratio per pass is less than 20%, the grain refinement may be insufficient. If a reduction ratio of more than 35% is to be obtained, the load load of the calender may become too large. Time. Further, when the strain rate is less than 3/sec, the grain refinement becomes insufficient, and the tendency of the fine particles and the coarse particles to be mixed appears. If the strain rate exceeds 10/sec, the load load of the calender becomes too large to be practical.

The rolling temperature after each pass is set to be 400 to 650 ° C in the case of hot rolling, whereby the coarsening of crystal grains is suppressed. When the rolling temperature is less than 400 ° C, the dynamic recrystallization is insufficient, and the tendency of the crystal grain size heterogeneity to increase becomes remarkable. If it exceeds 650 ° C, grain growth progresses and the average grain size exceeds 30 μm.

The final finishing hot rolling is carried out one to several times as necessary.

A better range of finishing hot rolling, preferably a rolling reduction of 25 to 35% per one pass, a strain rate of 5 to 10/sec, and a rolling temperature of 500 to 600 ° C after the pass, the finishing hot rolling Implemented more than 3 times.

Further, the rolling start temperature may not be 400 to 650 ° C, but the rolling start temperature and the pass schedule may be set so that the temperature at the end of each pass in the final stage of the hot rolling is 400 to 650 ° C.

Then, after such hot calendering, it is rapidly cooled at a cooling rate of 100 to 1000 ° C / min, and is lowered from a temperature of 400 to 650 ° C to a temperature of 200 ° C or less. By this rapid cooling, grain growth is suppressed, and a rolled plate of fine crystal grains can be obtained. If the cooling rate is less than 100 ° C / min, the effect of suppressing grain growth is poor. A cooling rate exceeding 1000 ° C / min does not contribute to further miniaturization. The method of rapid cooling can be set as a water spray for about 1 minute.

Then, in each pass, the rolling rate is over the entire rolling pass. The average value is 10 to 30%, and the strain rate is cold-rolled under the condition that the average value of all the rolling passes is 3 to 10/sec until the target thickness is reached.

When the reduction ratio per pass of the cold rolling is less than 10%, the grain refinement is insufficient, and the particle size unevenness is also increased, which is not preferable. If a reduction ratio of more than 30% per one pass is obtained, the load load of the calender becomes too large to be practical.

When the calendering strain rate of the cold rolling is less than 3/sec, the grain refinement becomes insufficient, and the tendency of the fine particles and the coarse particles to be mixed appears. If the strain rate exceeds 10/sec, the load load of the calender becomes too large to be practical.

In addition, the temperature of the cold-rolled sheet is below 200 °C.

In the heat treatment after cold rolling, it is maintained at 350 to 550 ° C for 1 to 2 hours. When the temperature is less than 350 ° C or the time is less than 1 hour, the recrystallization is insufficient, and the particle size unevenness is increased. If the temperature exceeds 550 ° C or the time exceeds 2 hours, the grain growth progresses and the average grain size exceeds 30 μm.

The calendered sheet thus obtained is subjected to corrective pressurization and roll correction After correction by a roller leveller or the like, fine adjustment is performed to a desired size by machining such as milling or electric discharge machining. The arithmetic mean surface roughness (Ra) of the sputtered surface of the finally obtained sputtering target is preferably 0.2 to 2 μm.

The silver for forming a conductive film of the present embodiment thus obtained The alloy sputtering target can suppress abnormal discharge and suppress the occurrence of spatter even if large power is supplied during sputtering. By sputtering the target, you can get a reflection A conductive film with high rate and excellent durability. In addition, sputtering is performed by using the silver alloy sputtering target material for forming a conductive film, whereby a conductive film having good corrosion resistance and heat resistance and low electrical resistance can be obtained. In particular, it is quite 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.

[Examples] (Example 1)

Ag, a purity of 99.99% by mass or more, and In, Sn, Sb, and Ga having a purity of 99.9% by mass or more are prepared as an additive raw material, and are loaded into a high-frequency induction melting furnace in which a graphite crucible is built. The total mass at the time of melting is set to be about 1100 kg.

At the time of melting, Ag was first melted, Ag was melted, and the raw material was added to have a target composition shown in Table 1, and the alloy melt was sufficiently stirred by the stirring effect by induction heating, and then cast in a mold made of cast iron.

The shrinkage cavity of the ingot obtained by the casting is partially cut off, and the surface that is in contact with the mold is subjected to face milling to obtain a flawless portion having a rough size of 640 × 640 × 180 (mm). a rectangular parallelepiped ingot.

Heating the ingot to 650 ° C, changing the rolling direction in the middle and The heat is repeatedly rolled up to a thickness of 67 mm. In the hot rolling, the conditions from the final pass to the first two passes (the reduction ratio per one pass, the strain rate, and the sheet temperature after the pass) are as shown in Table 1. Order.

After the completion of the hot rolling, the rolled sheet was cooled to 200 ° C or lower under the conditions shown in Table 1.

After cooling, a plurality of cold rollings were applied to finally form a sheet of 1700 x 2100 x 20 (mm) size. The total calendering rate of the cold rolling, the rolling reduction per pass, the average value of the full calendering pass, and the strain rate in the total calendering pass are as specified in Table 1.

The cold rolled sheet was subjected to heat treatment in accordance with the conditions (temperature, time) shown in Table 1.

After the heat-treated sheet was passed through a roll straightener to correct the strain, it was machined to a size of 1600 × 2000 × 15 (mm) to serve as a target.

(Examples 2 to 21, Comparative Examples 1 to 11)

As in the case of Example 1, the conditions of the target composition and the hot rolling in the finishing heat rolling from the final hot rolling pass to the first two times (the rolling rate and strain rate per pass) , plate temperature after the pass), cooling rate after hot rolling, cold rolling conditions (total rolling rate of cold rolling, reduction ratio per pass, average value of full cold rolling pass, strain rate at full The conditions of the heat treatment conditions (temperature, time) after cold rolling are subjected to melting, casting, hot rolling, cooling, cold rolling, heat treatment, and then produced by correction and machining. The targets of Examples 2 to 2I and Comparative Examples 1 to 11. In Table 1, it is indicated that the cooling rate is cooled by water spray, and the waterless cooling is simply placed in the cooler.

For the obtained target, the warpage after machining is measured, The average particle size and its heterogeneity are measured by the sputtering apparatus to measure the number of abnormal discharges during sputtering, and the surface roughness, reflectance, and chlorination resistance of the conductive film obtained by the sputtering are measured. , resistivity.

(1) Warpage after machining

The amount of warpage per length of 1 m was measured for the silver alloy sputtering target after machining, and the results are shown in Table 2.

(2) Average particle size and its heterogeneity

The particle size of the silver alloy crystal grains was measured from the above-described targets, and the sample was uniformly taken from 16 locations as described in the embodiment, and the average particle diameter of the surface when viewed from the sputtering surface of each sample was measured. The average value of the average particle diameter of each sample, that is, the average particle diameter of the silver alloy crystal grains, and the unevenness of the average particle diameter of the silver alloy crystal grains were calculated.

(3) Abnormal discharge times during sputtering

From any portion of the target manufactured as described above, a circular plate having a diameter of 152.4 mm and a thickness of 6 mm was cut and welded to a copper back plate. This welded target was used as a target for splash evaluation at the time of sputtering, and the number of abnormal discharges during sputtering was measured.

In this case, the soldered target is mounted to a general magnetron sputtering device, after exhausting to 1 × 10 ^-4 Pa, with Ar gas pressure: 0.5 Pa, input power: DC 1000 W, distance between target substrates : Sputtering is performed under conditions of 60 mm. The number of abnormal discharges in the initial 30 minutes of use and the deposition and replacement of the deposition prevention plate for 4 hours were repeated, and the target was consumed by intermittent sputtering for 20 hours, and then measured 30 times. The number of abnormal discharges in minutes. The number of abnormal discharges was measured by an arc counting function of a DC power source (model: RPDG-50A) manufactured by MKS Instruments.

(4) Evaluation of basic characteristics as a conductive film (4-1) Surface roughness of the film

The target for evaluation was subjected to sputtering under the conditions described above, and a film was formed on a glass substrate of 20 × 20 (mm) at a film thickness of 100 nm to obtain a silver alloy film.

Further, in order to evaluate heat resistance, the silver alloy film was subjected to heat treatment at 250 ° C for 10 minutes, and then the average surface roughness (Ra) of the silver alloy film was measured by atomic force microscopy (AFM).

(4-2) Reflectance

The absolute reflectance of the silver alloy film formed as described above on a glass substrate of 30 × 30 (mm) with respect to a wavelength of 550 nm was measured by a photometer.

Further, in order to evaluate the corrosion resistance, the film was held in a constant temperature and high humidity bath at a temperature of 80 ° C and a humidity of 85% for 100 hours, and then the absolute reflectance of the silver alloy film formed as described above with respect to the wavelength of 550 nm was measured by a spectrophotometer.

(4-3) Chloride resistance

In order to confirm the effect of adding Ga, a 5 wt% NaCl aqueous solution was sprayed on the film surface of the silver alloy film formed as described above using the Ga-added target (Examples 16, 18, 20, and 21). The spray was carried out at a height of 20 cm from the film surface and at a distance of 10 cm from the edge of the substrate, in a direction parallel to the film surface, so that the NaCl aqueous solution sprayed onto the film was as free as possible to adhere to the film. Spray every 1 minute, repeat 5 times, rinse with pure water for 3 times, then spray dry air to blow the water and dry.

The surface of the silver alloy film was visually observed after the above salt spray, and the state of the surface was evaluated. The evaluation criteria for the chlorination resistance are such that it is impossible to confirm the turbidity or speckle, or it is only possible to confirm that some of them are set to be good "○", and it is possible to confirm that the white turbidity or the spotting is a bad "X". The state of the surface is evaluated in two stages. For the target without added Ga, no evaluation was made, so the sign "-".

(4-4) Resistivity of the film

The resistivity of the silver alloy film formed as described above was measured.

The results of these evaluations are shown in Table 2.

In the target of the embodiment, the average grain size of the silver alloy crystal grains falls In the range of 1 μm or more and less than 30 μm, the heterogeneity of the grain size of the silver alloy is within 30% of the average grain size of the crystal grains of the silver alloy. The warpage after machining is also small, and the number of abnormal discharges during sputtering is small either at the beginning of use or after consumption. In addition, when Sb or Ga is added, the average grain size tends to be small, and the number of abnormal discharges is as small as one or less.

Further, the conductive film obtained by the target of the examples was excellent in reflectance and electrical resistivity, and the surface roughness Ra was as small as 1.4 nm or less.

Further, the conductive film obtained from the target to which Ga is added has excellent chlorination resistance, and it is known that it is effective for a conductive film such as a touch panel.

The present invention is not limited to the above-described embodiments, and various modifications can be added without departing from the spirit and scope of the invention.

[Industry Utilization]

According to the silver alloy sputtering target for forming a conductive film of the present invention and the silver alloy sputtering target for forming a conductive film produced by the production method of the present invention, it is possible to further increase the power by sputtering. Suppress arcing and splashing. As a result, a conductive film having high reflectance and excellent durability can be formed.

Claims (4)

A silver alloy sputtering target for forming a conductive film is a silver alloy sputtering target having a composition of the following components, that is, a total of 0.1 or more of elements containing solid solution of Ag, that is, In and Sn, is 0.1. ~1.5% by mass, the remainder consists of Ag and unavoidable impurities, characterized in that the average grain size of the crystal grains of the alloy is 1 μm or more and less than 30 μm, and the grain size heterogeneity of the crystal grains is an average particle diameter Less than 30%. A silver alloy sputtering target for forming a conductive film is a silver alloy sputtering target having a composition of the following components, that is, a total of 0.1 or more of elements containing solid solution of Ag, that is, In and Sn, is 0.1. In addition, one or more of Sb and Ga, which are elements which are solid-solubilized in Ag, are 0.1 to 2.5% by mass in total, and the remainder is composed of Ag and unavoidable impurities, and is characterized by the alloy. The average grain size of the crystal grains is 1 μm or more and less than 30 μm, and the grain size heterogeneity of the crystal grains is 30% or less of the average particle diameter. A method for producing a silver alloy sputtering target for forming a conductive film has a composition of 0.1 to 1.5% by mass in total of one or more of In and Sn, and the balance is Ag and inevitably A method for producing a silver alloy sputtering target by melt-casting an ingot composed of impurities, sequentially applying a hot rolling process, a cooling process, a cold rolling process, a heat treatment process, and a mechanical processing project, wherein the heat is In the rolling process, the rolling calendering of one pass or more is included, and the rolling reduction rate per pass of the finishing hot rolling is 20 to 35%, and the strain rate is 3 to 10/sec, and after the pass The temperature is 400~650°C; in the above cooling project, it is 100~ The cooling rate of 1000 ° C / min is rapidly cooled to below 200 ° C; in the cold rolling process, the average reduction rate per pass is 10 to 30% of the total calendering pass, and the strain rate is in the full calendering pass. The average value is 3 to 10/sec, and the total reduction ratio is 40 to 80% until the target thickness is reached. In the heat treatment process, the temperature is maintained at 350 to 550 ° C for 1 to 2 hours. A method for producing a silver alloy sputtering target for forming a conductive film, which comprises a composition of the following composition, that is, a total of one or more of In and Sn is 0.1 to 1.5% by mass, and further contains Sb and Ga. One or more of the above-mentioned molten cast ingots composed of Ag and unavoidable impurities, and the hot rolling process, cooling engineering, cold rolling engineering, heat treatment engineering, and mechanical processing engineering are sequentially applied. A method for producing a silver alloy sputtering target, characterized in that: in the hot rolling process, the hot rolling is included in one pass or more, and the rolling reduction rate per one pass of the finishing hot rolling is 20~35%, the strain rate is 3~10/sec, and the temperature after the pass is 400~650°C; in the cooling project, it is rapidly cooled to below 200 °C with a cooling rate of 100~1000 °C/min; In the cold rolling project, the average reduction rate per pass is 10~30% in the total calendering pass, and the average strain rate is 3~10/sec in the total calendering pass, with a total reduction rate of 40. ~80% is carried out until the target thickness is reached; in the heat treatment project, it is maintained at 350~550 °C for 1-2 hours. .