TW201443250A - Cu-Ga alloy sputtering target, cast object for the sputtering target, and manufacturing method thereof - Google Patents

Abstract

Disclosed herein is a Cu-Ga alloy cylindrical sputtering target, which is a cylindrical sputtering target of Cu-Ga alloy subjected to melting and casting; the Cu-Ga alloy contains more than 25at% and less than 35at% of Ga, and the rest is composed of Cu and unavoidable impurities, which characterized in that when the cylindrical sputtering target is cut into ring-shaped sections, the cross-section has pores of equal circles with a diameter of 50μm or more, and the number of pores is 0.3 /cm2 or less. In this Cu-Ga alloy target, if the concentration of Ga is above 25at%, the brittleness will be very high, making it very difficult to manufacture by means of melting and casting. Also, although production can be made by sintering powder, due to the high concentration of oxygen and numerous impurities as well, characteristics of solar cells will be undesirably deteriorated. Accordingly, an object of the present invention is to provide a target which does not crack and has reduced number of pores (holes or voids) even if the Ga concentration in the Cu-Ga alloy is within the range of 25at% ~ 35at%.

Description

Cu-Ga alloy sputtering target, casting product for sputtering target, and the like

The present invention relates to a pore (also referred to as a pore or a pore) used in forming a Cu-In-Ga-Se (hereinafter referred to as CIGS) quaternary alloy thin film as a light absorbing layer of a thin film solar cell layer. Void.) Reduced Cu-Ga alloy sputtering target, casting product for sputtering target, and the like.

In recent years, mass production of high-efficiency CIGS-based solar cells, which are thin-film solar cells, has been progressing, and as a method of producing the light-absorbing layer, a vapor deposition method and a selenization method are known. Although the solar cell manufactured by the vapor deposition method has the advantages of high conversion efficiency, it has the disadvantages of low film formation speed, high cost, and low productivity, and the selenization method is more suitable for mass production in the industry.

The main steps of the selenization method are as follows. First, a molybdenum electrode layer is formed on a soda lime glass substrate, and after sputtering to form a Cu-Ga layer and an In layer, a CIGS layer is formed by high temperature treatment in a hydrogenated selenium gas. In the step of forming the CIGS layer by this selenization method, a Cu-Ga target is used when the Cu-Ga layer is formed by sputtering.

Various manufacturing conditions and characteristics of constituent materials affect the conversion efficiency of CIGS-based solar cells, and the characteristics of CIGS films also have a significant impact.

The method for producing a Cu-Ga target includes a melting method and a powder method. In general, a Cu-Ga target produced by a melting method has disadvantages in that it has less impurity contamination. For example, fine pores are generated in the target. This can result in abnormal discharge and particles during sputtering. This is the original cause of the film quality reduction because.

Further, at the final stage of the cooling of the molten metal, shrinkage cavities are likely to occur, and the characteristics of the peripheral portion of the shrinkage cavities are also poor, which may be unusable due to processing to a predetermined shape, and the yield is poor.

In the related literature (Patent Document 1) of the Cu-Ga target produced by the melting method, although the description of the composition segregation is not observed, the analysis results and the like are not disclosed at all. Moreover, there is no attention to the occurrence of fine pores in the target, and there is no solution.

On the other hand, a target produced by a powder method generally has problems such as low sintered density and high impurity concentration. Patent Document 2 related to a Cu-Ga target discloses a sintered body target. The patent document has a description of the prior art relating to brittleness which is prone to cracks and defects when cutting a target, and in order to solve this problem, two types are manufactured. The powder is mixed and sintered. Further, in the powders of the two types, one of the powders is a powder for increasing the Ga content, and the other powder is a powder having a reduced Ga content to form a two-phase coexisting structure surrounded by a grain boundary phase.

Since this step produces two types of powders, the steps are repeated, and the oxygen concentration of the metal powder becomes high, and it is not expected to increase the relative density of the sintered body.

For targets with low density and high oxygen concentration, abnormal discharge or particles will occur. If there are particles and other irregularities on the surface of the sputter film, it will adversely affect the subsequent CIGS film characteristics. Finally, it is likely to cause CIGS solar cells. The conversion efficiency has dropped dramatically.

Further, Patent Document 3 discloses a Cu-Ga alloy sputtering target having an average crystal grain size of 10 μm or less and a porosity of 0.1% or less, which can form Cu- excellent in uniformity (membrane uniformity) of a film component composition. Ga sputter coating, which shows that arcing can be reduced during sputtering, and the strength is high, and the crack in the sputtering process can be suppressed, and the compactness is reduced, but the problem as a sintered body cannot be solved at all. .

A major problem with the Cu-Ga sputtering target produced by the powder method is that the sintered body produced has a high oxygen concentration and a high amount of impurities, so that the quality is not necessarily good and the production cost is increased. From this point of view, it is preferable to be a melting or casting method, but as described above, there is a problem in manufacturing, and the quality of the target itself cannot be improved.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2000-73163

Patent Document 2: JP-A-2008-138232

Patent Document 3: Japanese Laid-Open Patent Publication No. 2010-265544

When the Ga concentration is 25 at% or more, the Cu-Ga alloy target has a very high brittleness and is difficult to manufacture by melt casting. Further, although it can be produced by powder sintering, since the oxygen concentration is high and the amount of impurities is also large, the characteristics of the solar cell are deteriorated. Therefore, the object of the present invention is to provide a target which does not cause cracks even if the CuGa alloy has a Ga concentration of 25 at% to 35 at%, and the pores (voids or voids) are reduced, so that abnormal discharge can be performed. Wait for a good splash.

In order to solve the above problems, the inventors of the present invention have found that a cylindrical casting having a composition of Ga and being melted and melted by melting is optimized by melting conditions and HIP conditions. The present invention can be accomplished by obtaining a target having few pores.

From the above findings, the present invention provides the following invention.

1) A cylindrical cast product of Cu-Ga alloy, which is a cylindrical cast product of a melted and cast Cu-Ga alloy, wherein the Ga of the Cu-Ga alloy is 25 at% or more and 35 at% or less, and the balance is Cu and In the case where the cylindrical cast product is cut into a circular slice, the number of the pores having a circular diameter of 100 μm or more in the cross section is 3.5 pieces/cm ² or less.

The "equal diameter" of the pores refers to the diameter of a circle having the same area as the area of one pore of the irregular shape, and the same applies hereinafter.

2) A method for producing a Cu-Ga alloy cylindrical cast product, which is a method for melting and casting a Cu-Ga alloy to produce a cylindrical cast product, wherein the Ga of the Cu-Ga alloy is 25 at% or more and 35 at% or less The remaining portion is composed of Cu and unavoidable impurities, and is characterized in that the melting temperature is a high degree of vacuum of the alloy (melting point + 100) ° C or more and 1100 ° C or less, and the degree of vacuum is 5.0 × 10 ^-2 torr or more. , for melting and casting.

3) The method for producing a Cu-Ga alloy cylindrical cast product according to the above 2), wherein the melting temperature is (melting point + 100) ° C or more and 1040 ° C or less of the alloy.

(4) The method for producing a Cu-Ga alloy cylindrical casting according to the above 2) or 3), wherein the cylindrical casting is cut into a circular section by the manufacturing method, The number of pores having an equi-circle diameter of 100 μm or more in the cross section is 3.5/cm ² or less.

5) A Cu-Ga alloy cylindrical sputtering target, which is a Cu-Ga alloy sputtering target in which Ga is 25 at% or more and 35 at% or less, and the balance is composed of Cu and unavoidable impurities, and is characterized in that: The number of the pores having an equi-circle diameter of 50 μm or more is 0.3/cm ² or less.

6) A method for manufacturing a Cu-Ga alloy cylindrical sputtering target, which is a method for manufacturing a Cu-Ga alloy sputtering target, wherein the Ga of the Cu-Ga alloy is 25 at% or more and 35 at% or less, and the balance is Cu and The composition of the impurities to be avoided is characterized in that when the Cu-Ga alloy raw material is melted, the melting temperature is set to be (melting point + 100) ° C or more and 1100 ° C or less, and the degree of vacuum is higher than 5.0 × 10 ^-2 torr or more. The degree of vacuum is melted and cast to obtain a Cu-Ga alloy cylindrical cast product, and the pressure is 1500 kg/cm ² or more, the temperature is 750 ° C or higher, the melting point is -50 ° C or lower, and the holding time is 2 hours or longer. The Cu-Ga alloy cylindrical cast product is subjected to HIP (thermal pressure equalization) treatment and further processed into a target shape.

(7) The method for producing a Cu-Ga alloy cylindrical sputtering target according to the above 6), wherein the melting temperature is +100 ° C or more and 1040 ° C or less of the melting point of the alloy, and the degree of vacuum is 5.0 × 10 ^- After a high vacuum of ³ torr or more, melting and casting are carried out to form a Cu-Ga alloy cylindrical casting, and the pressing force is 1500 kg/cm ² or more, the temperature is 750 ° C or higher (melting point - 50) ° C or lower, and the holding time is 3 The Cu-Ga alloy cylindrical cast product was subjected to HIP treatment under the conditions of an hour or more.

(8) The method for producing a Cu-Ga alloy cylindrical sputtering target according to the above (7), wherein the number of pores having a circular diameter of 50 μm or more is 0.3/cm ² or less.

According to the present invention, there is an excellent effect that a target can be provided which does not cause cracks even in a CuGa alloy having a Ga concentration of 25 at% to 35 at%, and pores (also referred to as pores or The voids are reduced, so that good sputtering such as abnormal discharge can be performed. Moreover, compared with the sintered body target, it has the advantage of reducing the gas composition. By using a Cu-Ga alloy target having a cast structure having a small gas component (oxygen or the like) and having few pores, sputtering can be performed, and abnormal discharge and particle generation can be reduced, and a homogeneous Cu-Ga alloy film can be obtained. Moreover, it has an effect of greatly reducing the manufacturing cost of the Cu-Ga alloy target. Since the light absorbing layer and the CIGS-based solar cell can be produced from such a sputtering film, it is excellent in that it can suppress a decrease in conversion efficiency of the CIGS solar cell and can manufacture a low-cost CIGS-based solar cell.

Fig. 1 is an explanatory view showing the appearance of pores of a tissue which occurs after casting.

Fig. 2 is an explanatory view showing the results of gas analysis inside the micropores.

Figure 3 is a 2-ary state diagram of Cu-H.

Fig. 4 is an explanatory view showing an example of a casting method.

Fig. 5 is an explanatory view showing an example in which a cylindrical casting (casting) is cut into a circular section.

In the Cu-Ga alloy cylindrical casting of the present invention, Ga is 25 at% or more and 35 at% or less, and the balance is composed of Cu and unavoidable impurities, and is a Cu-Ga alloy in which the raw materials of these alloys are melted and cast. Cylindrical castings. Further, when the cylindrical cast product is cut into a circular slice, the number of pores having an equilateral diameter of 100 μm or more in the cross section is 3.5 pieces/cm ² or less.

By performing sputtering using a Cu-Ga alloy target having such a cast structure, abnormal discharge and particles can be reduced, and a homogeneous Cu-Ga-based alloy film can be obtained. Further, when a light-absorbing layer and a CIGS-based solar cell are produced by using the sputtering film obtained by using the Cu-Ga alloy target of the present invention, the conversion efficiency of the CIGS solar cell can be suppressed from being lowered, and a low-cost CIGS-based solar cell can be manufactured. .

The Ga content is indispensable for the formation of a Cu-Ga alloy sputtering film when manufacturing a CIGS-based solar cell, and the Cu-Ga alloy sputtering target of the present invention provides a Ga at 25 at% or more and 35 at% or less, and the remainder A melted, cast cylindrical Cu-Ga alloy sputtering target consisting of Cu and unavoidable impurities.

In the past, the sintered product was at a relative density of 95% or more (further at 98%). Above) as a target. The reason is that if the relative density is low, when the internal pores appear outside during the sputtering process, splash or abnormal discharge starting from the periphery of the pores may cause particles to be generated on the membrane or The surface is roughened, and abnormal discharge or the like starting from a surface nodule is likely to occur. The cast product can achieve a relative density of almost 100%, and as a result, it has an effect of suppressing generation of particles upon sputtering. This can be said to be one of the great advantages of castings.

In order to reduce the abnormal discharge and particles during sputtering, the pores must be eliminated as much as possible. However, in the case of a cylindrical shape like a rotating target, if a molten metal is injected into a mold, large pores (pores) which can be visually confirmed in units of 100 to 500 μm are produced.

Figure 1 shows a polished tissue pattern of one of the cut faces of a cast ingot. In the upper view of Fig. 1, it was confirmed that five pores (micropores) surrounded by ○ were observed. The figure below in Figure 1 is a photo of the tissue that magnifies one of them. Fine pores can be seen mainly at the grain boundaries of the crystal structure.

Inside this hole, hydrogen is mainly contained therein. The gas analysis inside the pores was measured by analyzing the gas while the cast piece was opened with a micro-drill, and it was confirmed that hydrogen gas was present as compared with the background value of the open hole of the drill.

The actual gas analysis has been carried out using a gas analyzer (Nippon Steel Technoresearch) and a mass spectrometer (a four-pole mass spectrometer manufactured by ANEVA). The results are shown in Fig. 2. In Fig. 2, The background value (top) and the analysis of the gas release (bottom).

Hydrogen is dissolved in copper during melting, but is captured by the solid phase during solidification. Therefore, in general, the micropores are finally removed by HIP processing or the like.

However, if there is a certain amount or more in the void per unit area, it may not be completely removed by the HIP treatment, and may remain in the interior of the ingot.

Therefore, the melting temperature of the Cu-Ga alloy in which Ga is 25 at% or more and 35 at% or less and the remainder is made of Cu is the melting temperature of the same alloy (melting point + 100) ° C or more and 1100 ° C or less. (further (melting point + 100) ° C or more and 1040 ° C or less), and a vacuum degree of 5.0 × 10 ^-2 torr or more (further, 5.0 × 10 ^-3 torr or more) is performed, and melting and casting are performed. Fine pores can be reduced or removed.

In other words, when the cylindrical cast product is cut into a circular slice, the number of pores having an equilateral diameter of 100 μm or more in the cross section is 3.5 pieces/cm ² or less.

The melting point of the alloy can be determined from the binary state diagram of Cu-Ga (Reference: ASM Binary Alloy database). For example, when Ga is 25 at%, the melting point is 890 ° C according to the binary system state diagram of Cu-Ga.

In this case, if the melting temperature exceeds 1100 ° C, the solubility of hydrogen in the liquid phase becomes high and cannot be sufficiently removed. More preferably, the melting temperature is below 1040 °C. Further, even if the degree of vacuum is 5 × 10 ^-3 torr or more, the gas component is solid-solved during the melting process and cannot be removed, so the above conditions are preferred.

Figure 3 shows a 2-ary state diagram of Cu-H. The hydrogen solid solution limit of Cu is 0.2 at% of about 1075 ° C, and the lower the temperature, the less. Moreover, if it exceeds the melting point of 1084 ° C, the degree of melting increases by a factor of three to 0.6 at%. Therefore, it is preferred to be in the above temperature range.

When a Cu-Ga alloy cylindrical sputtering target is produced, as described above, a melting temperature of a material having a Ga content of 25 at% or more and 35 at% or less and a remainder of Cu is a melting point of the alloy (melting point + 100) ° C or more and 1100 ° C. The following (more preferably, it is less than 1040 ° C), and the vacuum degree is a vacuum degree of 5.0 × 10 ^-2 torr or more, and after melting and casting to form a Cu-Ga alloy cylindrical casting, the pressing force is 1500 kg/ The Cu-Ga alloy cylindrical casting product is subjected to HIP treatment and processed into a condition of cm ² or more, a temperature of 750 ° C or more (melting point - 50) ° C or less, and a holding time of 2 hours or more (more preferably 3 hours or more). By the shape of the target, a Cu-Ga alloy cylindrical sputtering target having a number of pores having an equilateral diameter of 50 μm or more in the target of 0.3/cm ² or less can be obtained.

In the HIP treatment, if the pressure is less than 1500 kg/cm ² , the pores are not sufficiently eliminated, and if the temperature is less than 750 ° C, the gas component does not diffuse and remains. Moreover, it is necessary to keep the temperature of the high temperature for a certain period of time or longer. Specifically, it is preferably 2 hours or longer, more preferably 3 hours or longer. When the temperature holding time of the high temperature is insufficient, the gas components contained in the pores are not sufficiently diffused, and the pores (pores) remain more.

Fig. 4 shows an example of melt casting of a Cu-Ga alloy. In the form of a predetermined composition of CuGa alloy, a raw material for melting Cu and Ga is, for example, about 25 kg in a graphite crucible. In order to remove moisture, a graphite feed tank can be baked with a burner for about one hour.

Will have a core graphite mold (for example, OD 165 , inner diameter 125 , height 400mm) and the feeding trough are arranged in the chamber. After evacuating to a predetermined degree of vacuum, the crucible is heated by induction heating to melt the raw material. Then, at a point where the predetermined temperature is reached, the casting mold is injected through the feeding tank to produce a cylindrical Cu-Ga alloy ingot.

When evaluating a cylindrical Cu-Ga alloy ingot, as shown in FIG. 5, a cylindrical casting (casting) having a length of about 300 mm is cut into three parts at positions of 50 mm, 150 mm, and 250 mm from the top. The slices were sliced so that the thickness of each slice was 10 mm. Further, when cutting into a circular slice, as shown in Fig. 5, it is cut so that the cross-sectional direction is perpendicular to the longitudinal direction (not beveled).

The ingot obtained in this manner was ground using #400 abrasive paper. Then, the number of pores in the cross section is counted to confirm whether or not the requirements of the present invention are satisfied.

Further, melting and casting are carried out so that the pressing force is 1500 kg/cm ² or more, the temperature is in the range of 750 ° C to the melting point - 50 ° C, and the holding time is 2 hours or longer (if necessary, more than 3 hours), for Cu-Ga cylindrical castings alloy (ingot) subjected to HIP treatment is processed into a target, whereby the target can be obtained having a pore diameter of 50μm and the like of ^more or less Cu-Ga alloy in which the number of 0.3 / cm Cylindrical sputtering target. Further, the number of the pores may be 0/cm ² .

The sputtering target manufactured in the above manner, for example, has a sputtering power of direct current (DC) of 1000 W, an ambient gas of argon, a gas flow rate of 50 scm, and a sputtering pressure of 0.5 Pa, which allows the sputtering time to be 5 hours to 6 The number of abnormal discharges in one hour between hours is 10 or less, preferably 5 or less.

As described above, by controlling the casting conditions and performing the HIP treatment under appropriate conditions, the following CuGa alloy rotating target can be obtained: even if the Ga concentration is in the range of 25 to 35 at%, the target does not cause cracks, and the micro-reduction is caused. The hole reduces the number of abnormal discharges.

[Examples]

Next, an embodiment of the present invention will be described. In addition, this embodiment is only an example, and the invention is not limited by the embodiment. That is, all aspects or modifications other than the invention and the embodiments that can be grasped from the specification are included in the scope of the technical idea of the present invention.

(Example 1)

Using the casting apparatus shown in Fig. 4, 25 kg of the raw material was placed in a carbon crucible, and the chamber was brought into a vacuum environment of 5 × 10 ^-3 torr, and the crucible was heated to 1100 ° C by induction heating. Ga (purity: 4N) was adjusted to a composition ratio of Ga concentration of 25 at%, and the remainder was a raw material of copper (Cu: purity 4N).

After the raw material was completely melted, argon gas was introduced into the chamber to lower the temperature of the melt to 990 ° C, and when the melt temperature was stable, liquid discharge was started. Thereafter, the temperature at this time is the discharge temperature. The liquid discharge is performed by a method of injecting a mold through a feed tank. The shape of the crucible used in the melting is 320mm ×400mm , the mold is OD 165 , inner diameter 125 , height 400mm.

After casting, the ingot was taken out from the mold, and the cylindrical casting having a length of 300 mm was cut into three pieces at a position of 50 mm, 150 mm, and 250 mm from the top, and the thickness of each slice was 10 mm. After the ingot obtained in this manner was polished with a #400 abrasive paper, it was confirmed that the number of pores having a circular diameter of 100 μ or more in the cross section was found to be 0.8 per unit cm ² .

Further, the cylindrical article was subjected to HIP treatment under the conditions of a pressure of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 3 hours. As a result, casting pores completely (0) and the like having a diameter of above 50μm does not exist, satisfying 0.3 / cm ² or less. The results are shown in Table 1.

The cylindrical casting was machined into a cylindrical inner diameter of 135 mm, an outer diameter of 150 mm, and a length of 75 mm, and joined to a titanium backing tube to form a two-stage sputtering target having a total length of 150 mm. Sputtering. The sputtering power was 1000 W of direct current (DC), the ambient gas was argon, the gas flow rate was 50 sccm, and the pressure at the time of sputtering was 0.5 Pa. The number of abnormal discharges in one hour between 5 hours and 6 hours after the sputtering time was counted, and the result was 0 times. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 1)

The cylindrical casting cast in the same manner as in Example 1 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 650 ° C, and a holding time of 3 hours. There is a number of pores having a circular diameter of 50 μm or more in the casting, and 0.5 per unit cm ² . When the treatment was carried out under the HIP condition (low temperature) different from that of Example 1, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 12, which was a result of a large number of abnormal discharges.

(Example 2)

The cylindrical casting cast in the same manner as in Example 1 was subjected to a HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the discharge temperature was 1040 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.4 per unit cm ² , and the number of pores after HIP is 0 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 0. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 2)

The cylindrical casting cast in the same manner as in Example 2 was subjected to HIP treatment under the conditions of a pressing pressure of 1500 kg/cm ² , a temperature of 650 ° C, and a holding time of 3 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.4 per unit cm ² , and the number of pores after HIP is 0.5 per unit cm ² .

When the treatment was carried out under the HIP condition (low temperature) different from that of Example 2, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 20, which was a result of a large number of abnormal discharges.

(Example 3)

The cylindrical casting cast in the same manner as in Example 1 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the discharge temperature was 1,100 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 3.2 per unit cm ² , and the number of pores after HIP is 0.2 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 3)

A cylindrical casting cast in the same manner as in Example 3 was applied at a pressure of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 3, except that a low vacuum of 5 × 10 ^-1 torr (vacuum degree before liquid discharge) was formed. Under the condition of hours, HIP processing is implemented. There are the number of pores having a circular diameter of 50 μm or more in the casting, 4.5 per unit cm ² , and the number of pores after HIP is 0.6 per unit cm ² .

As described above, when the degree of vacuum (low vacuum) different from that of Example 3 was used, the number of pores increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 36, which was a result of abnormal discharge.

(Example 4)

The additive element Ga (purity: 4N) was adjusted to have a composition ratio of Ga concentration of 30 at%, and the raw material was completely melted in the same manner as in Example 1.

After the raw material was completely melted, argon gas was introduced into the chamber to lower the temperature of the melt to 950 ° C, and when the melt temperature was stable, liquid discharge was started. The size of the liquid discharge method and the mold was the same as in the first embodiment.

For the cast cylindrical casting, HIP treatment was carried out under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 2 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.3 per unit cm ² , and the number of pores after HIP is 0.1 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 4)

The cylindrical casting cast in the same manner as in Example 4 was subjected to HIP treatment under the conditions of a pressing pressure of 1500 kg/cm ² , a temperature of 650 ° C, and a holding time of 3 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.3 per unit cm ² , and the number of pores after HIP is 0.6 per unit cm ² .

When the treatment was carried out under the HIP condition (low temperature) different from that of Example 4, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 32, which was a result of abnormal discharge.

(Example 5)

The cylindrical casting cast in the same manner as in Example 4 was subjected to HIP treatment under the conditions of a pressing pressure of 1500 kg/cm ² , a temperature of 800 ° C, and a holding time of 3 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.3 per unit cm ² , and the number of pores after HIP is 0 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was one. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Example 6)

A cylindrical casting cast in the same manner as in Example 4 was carried out under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 4 hours, except that the vacuum was 5 × 10 ^-2 torr. HIP processing. There are the number of pores having a circular diameter of 50 μm or more in the casting, 3.2 per unit cm ² , and the number of pores after HIP is 0.2 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Example 7)

The cylindrical casting cast in the same manner as in Example 4 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the discharge temperature was 1040 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 2.2 per unit cm ² , and the number of pores after HIP is 0.3 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was four. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 5)

The cylindrical casting cast in the same manner as in Example 7 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 650 ° C, and a holding time of 3 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 2.2 per unit cm ² , and the number of pores after HIP is 0.8 per unit cm ² .

When the treatment was carried out under the HIP condition (low temperature) different from that of Example 7, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 64, which was a result of abnormal discharge.

(Comparative Example 6)

The cylindrical casting cast in the same manner as in Example 7 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 1 hour. There are the number of pores having a circular diameter of 50 μm or more in the casting, 2.2 per unit cm ² , and the number of pores after HIP is 0.5 per unit cm ² .

When the treatment was carried out under the HIP condition (short time) different from that of Example 7, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 26, which was a result of a large number of abnormal discharges.

(Example 8)

The cylindrical casting cast in the same manner as in Example 7 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 2 hours, except that the degree of vacuum was 5 × 10 ^-4 torr. There is a number of pores having a circular diameter of 50 μm or more in the casting, 1.8 per unit cm ² , and the number of pores after HIP is 0 per unit cm ² , and satisfies 0.3 pieces/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was one. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Example 9)

The cylindrical casting cast in the same manner as in Example 7 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the degree of vacuum was 5 × 10 ^-2 torr. There are the number of pores having a circular diameter of 50 μm or more in the casting, 4.0 per unit cm ² , and the number of pores after HIP is 0.3 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was three. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Embodiment 10)

The cylindrical casting cast in the same manner as in Example 4 was subjected to a HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 800 ° C, and a holding time of 3 hours, except that the discharge temperature was 1050 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 3.1 per unit cm ² , and the number of pores after HIP is 0.2 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 7)

The cylindrical casting cast in the same manner as in Example 4 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the melting temperature was raised to 1,180 ° C and the liquid was directly discharged. . There are the number of pores having a circular diameter of 50 μm or more in the casting, 4.3 per unit cm ² , and the number of pores after HIP is 0.5 per unit cm ² .

When the treatment was carried out at a melting temperature (high temperature) different from that of Example 4, the number of pores increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 28, which was a result of a large number of abnormal discharges.

(Comparative Example 8)

The cylindrical casting cast in the same manner as in Example 4 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the discharge temperature was 1200 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 5.4 per unit cm ² , and the number of pores after HIP is 0.7 per unit cm ² .

When the treatment was carried out at a discharge temperature (high temperature) different from that of Example 4, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 49, which was a result of a large number of abnormal discharges.

(Example 11)

The additive element Ga (purity: 4N) was adjusted to a composition ratio of a Ga concentration of 35 at%, and the raw material was completely melted in the same manner as in Example 1.

After the raw material is completely melted, argon gas is introduced into the chamber to reduce the temperature of the melt to 910 ° C. When the melt temperature is stable, the liquid discharge is started. The size of the liquid discharge method and the mold was the same as in the first embodiment.

For the cast cylindrical casting, HIP treatment was carried out under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 2 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.5 per unit cm ² , and the number of pores after HIP is 0.2 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 9)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing pressure of 1500 kg/cm ² , a temperature of 650 ° C, and a holding time of 3 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.5 per unit cm ² , and the number of pores after HIP is 0.6 per unit cm ² .

When the treatment was carried out under the HIP condition (low temperature) different from that of Example 11, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 40, which was a result of a large number of abnormal discharges.

(Embodiment 12)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing pressure of 1500 kg/cm ² , a temperature of 750 ° C, and a holding time of 5 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 1.5 per unit cm ² , and the number of pores after HIP is 0 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 0. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Example 13)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the degree of vacuum was 5 × 10 ^-2 torr. There is a number of pores having a circular diameter of 50 μm or more in the casting, 3.3 per unit cm ² , and the number of pores after HIP is 0.3 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was three. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 10)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the degree of vacuum was 5 × 10 ^-1 torr. There is a number of pores having a circular diameter of 50 μm or more in the casting, 4.2 per unit cm ² , and the number of pores after HIP is 0.4 per unit cm ² .

When the treatment was carried out under a vacuum (low vacuum) different from that of Example 11, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 11 times, which resulted in a large number of abnormal discharges.

(Example 14)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 2 hours, except that the discharge temperature was 1040 ° C. The number of pores having a circular diameter of 50 μm or more in the casting is 2.9 per unit cm ² , and the number of pores after HIP is 0.1 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 11)

The cylindrical casting cast in the same manner as in Example 14 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 600 ° C, and a holding time of 3 hours. There are the number of pores having a circular diameter of 50 μm or more in the casting, 2.9 per unit cm ² , and the number of pores after HIP is 1.0 per unit cm ² .

When the treatment was carried out under the HIP condition (low temperature) different from that of Example 11, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 72, which was a result of a large number of abnormal discharges.

(Example 15)

The cylindrical casting cast in the same manner as in Example 11 was subjected to a HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the degree of vacuum was 5 × 10 ^-4 torr. There are the number of pores having a circular diameter of 50 μm or more in the casting, 2.4 per unit cm ² , and the number of pores after HIP is 0 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was one. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 12)

The cylindrical casting cast in the same manner as in Example 14 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the degree of vacuum was 5 × 10 ^-1 torr. There are the number of pores having a circular diameter of 50 μm or more in the casting, 4.3 per unit cm ² , and the number of pores after HIP is 0.5 per unit cm ² .

When the treatment was carried out under a vacuum (low vacuum) different from that of Example 14, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 34, which was a result of a large number of abnormal discharges.

(Embodiment 16)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 6 hours, except that the discharge temperature was 1050 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 3.1 per unit cm ² , and the number of pores after HIP is 0.2 per unit cm ² , which satisfies 0.3/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was two. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Example 17)

The cylindrical casting cast in the same manner as in Example 11 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the discharge temperature was 1,100 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 3.5 per unit cm ² , and the number of pores after HIP is 0.3 per unit cm ² , which satisfies 0.3 pieces/cm ² or less. The results are shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was four. Thereby, the purpose of the cost case can be reached. The results are shown in Table 1.

(Comparative Example 13)

The cylindrical casting cast in the same manner as in Example 14 was subjected to HIP treatment under the conditions of a pressing force of 1500 kg/cm ² , a temperature of 750 ° C and a holding time of 3 hours, except that the discharge temperature was 1200 ° C. There are the number of pores having a circular diameter of 50 μm or more in the casting, 5.5 per unit cm ² , and the number of pores after HIP is 1.2 per unit cm ² .

When the treatment was carried out at a discharge temperature (high temperature) different from that of Example 14, the number of pores was increased. The results are also shown in Table 1. Sputtering was carried out under the same conditions as in Example 1. As a result, the number of abnormal discharges was 84, which was a result of a large abnormal discharge.

[Industrial availability]

According to the present invention, there is an excellent effect that a CuGa alloy having a Ga concentration of 25 at% to 35 at% can be provided without causing cracks and a target in which pores (voids or voids) are reduced. Moreover, compared with the sintered body target, it has the advantage of reducing the gas composition. In this way, sputtering is performed by using a Cu-Ga alloy target having a cast structure having a small gas component and a small number of pores, and the Cu-Ga alloy having a small amount of occurrence of abnormal discharge and generation of particles can be obtained. The film can greatly reduce the manufacturing cost of the Cu-Ga alloy target.

Since the light absorbing layer and the CIGS-based solar cell can be produced by using such a sputtering film, it is suitable for a solar cell for suppressing a decrease in conversion efficiency of a CIGS solar cell.

Claims (8)

A Cu-Ga alloy cylindrical casting product is a cylindrical casting of a melted and cast Cu-Ga alloy. The Ga of the Cu-Ga alloy is 25 at% or more and 35 at% or less, and the balance is Cu and inevitable. In the case of cutting the cylindrical cast product into a circular slice, the number of the pores having a circular diameter of 100 μm or more in the cross section is 3.5 pieces/cm ² or less. A method for producing a Cu-Ga alloy cylindrical casting product, which is a method for melting and casting a Cu-Ga alloy to produce a cylindrical casting product, wherein the Ga of the Cu-Ga alloy is 25 at% or more and 35 at% or less, and the remaining Partly composed of Cu and unavoidable impurities, the melting temperature is set to (the melting point +100) ° C or more and 1100 ° C or less, and the degree of vacuum is 5.0 × 10 ^-2 torr or more. Melting and casting. The method for producing a Cu-Ga alloy cylindrical cast product according to the second aspect of the patent application is characterized in that the melting temperature is (melting point + 100) ° C or more and 1040 ° C or less of the alloy. The method for producing a Cu-Ga alloy cylindrical casting according to the second or third aspect of the patent application, wherein the cross-section is made when the cylindrical casting is cut into a circular section by the manufacturing method The number of pores having an equi-circle diameter of 100 μm or more is 3.5/cm ² or less. A Cu-Ga alloy cylindrical sputtering target is a Cu-Ga alloy sputtering target in which Ga is 25 at% or more and 35 at% or less, and the balance is composed of Cu and unavoidable impurities, and the target has 50 μm. The number of the fine holes having the above-mentioned equal-diameter diameter is 0.3 pieces/cm ² or less. A method for manufacturing a Cu-Ga alloy cylindrical sputtering target, which is a method for manufacturing a Cu-Ga alloy sputtering target, wherein the Ga of the Cu-Ga alloy is 25 at% or more and 35 at% or less, and the balance is Cu and inevitable The impurity composition is characterized in that when the Cu-Ga alloy raw material is melted, the melting temperature is set to a high degree of vacuum of the alloy (melting point + 100) ° C or more and 1100 ° C or less, and the degree of vacuum is 5.0 × 10 ^-2 torr or more. After melting and casting, a Cu-Ga alloy cylindrical casting product is produced, and the pressure is 1500 kg/cm ² or more, the temperature is 750 ° C or higher (melting point - 50) ° C or lower, and the holding time is 2 hours or longer. The Cu-Ga alloy cylindrical cast product is subjected to HIP treatment and further processed into a target shape. The method for producing a Cu-Ga alloy cylindrical sputtering target according to the sixth aspect of the invention, wherein the melting temperature is the alloy (melting point + 100) ° C or more and 1040 ° C or less, and the degree of vacuum is 5.0 × 10 ^-3 torr or higher vacuum degree, melting and casting, after forming a Cu-Ga alloy cylindrical casting, the pressing pressure is 1500kg/cm ² or more, the temperature is 750 ° C or higher (melting point - 50) ° C or less, and the holding time is The Cu-Ga alloy cylindrical cast product was subjected to HIP treatment under conditions of 3 hours or longer. The method for producing a Cu-Ga alloy cylindrical sputtering target according to the seventh aspect of the invention, wherein the number of pores having an equilateral diameter of 50 μm or more is 0.3/cm ² or less.