TWI458847B - Cu-Ga alloy sintered body sputtering target, a method for manufacturing the target, a light absorbing layer made of a Cu-Ga alloy sintered body target, and a CIGS solar cell using the light absorbing layer - Google Patents

Description

Cu-Ga alloy sintered body sputtering target, method for producing the same, light absorbing layer made of Cu-Ga alloy sintered body target, and CIGS solar cell using the light absorbing layer

The present invention relates to a Cu-Ga alloy sintered body sputtering target used for forming a Cu-In-Ga-Se (hereinafter referred to as CIGS) quaternary alloy thin film (that is, a light absorbing layer of a thin film solar cell layer), A method for producing a target, a light absorbing layer made of a Cu-Ga alloy sintered body target, and a CIGS-based solar cell using the light absorbing layer.

In recent years, mass production of CIGS-based solar cells having high efficiency as thin-film solar cells is progressing, and vapor deposition methods and selenization methods are known as methods for producing light-absorbing layers. 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 approximate procedure for the selenization method is as follows. First, a molybdenum electrode layer is formed on a soda lime glass substrate, and a Cu-Ga layer and an In layer are formed by sputtering thereon, and then a CIGS layer is formed by high temperature treatment in a hydrogenated selenium gas. A Cu-Ga target is used in the sputtering film formation of the Cu-Ga layer in the CIGS layer formation process by this selenization method.

The manufacturing method of the Cu-Ga target includes a melting method and a powder method. In general, the Cu-Ga target produced by the melting method has less impurity contamination, but has problems such as large composition segregation and a decrease in yield due to a shrinkage cavity. The target produced by the powder method has a sintered density. Low, high oxygen concentration and other issues.

Various factors will affect the conversion efficiency of CIGS solar cells, and the CIGS film characteristics will also have a great impact. The characteristics of the Cu-Ga film before the formation of the CIGS film will also affect the conversion efficiency of the solar cell. It has a big impact. The target obtained by sintering the powder has a characteristic that the composition is less segregated, easier to manufacture, and easy to adjust the composition as needed, compared with the melted product, and has a larger advantage than the melted product.

However, the target obtained by sintering has a problem that particles are liable to be generated. In particular, if there are foreign substances such as particles on the surface of the film, the CIGS film characteristics will be adversely affected, and the conversion efficiency of the CIGS solar cell will be greatly reduced. The cause of the particles is abnormal discharge during sputtering, which is related to the density of the target. Further, since the powder is used, there is a tendency that oxygen or oxygen is mixed into the powder to cause an increase in the oxygen concentration.

In the literature on the abnormal discharge during sputtering by a Gu-Ga target and the generation of particles on the film (Patent Document 1), only the abnormal discharge is described, and only the relative density is 95%. The above is the reason. In this document, the Cu-Ga target system is produced by a melting method.

In general, the melted product is of higher density than the sintered product, and is usually less than 100% dense. However, the paragraph [0010] of Patent Document 1 describes "a high density of a relative density of 95% or more", and there is a description of achieving such a degree of density.

However, a relative density of about 95% is definitely not called high density. In fact, in this patent document 1, in the melted product, pores and poor pores (voids) which lower the density are generated.

Further, although the description of the composition segregation has not been observed, the analysis results and the like are not disclosed at all. From the description of the relative density of the above-mentioned degree, only the improvement of the segregation of the level of the recognized level is described.

In general, the melting method generally has a large compositional segregation, and since it has not undergone a special step for eliminating segregation, it is considered that it will have a general degree of segregation.

The segregation characteristic of such a molten product has a problem that a change in film composition occurs during sputtering. The sputtering conditions are also unknown.

At the beginning of the sputtering film formation, even if there is no abnormal discharge or the like, the sputtering surface is rough due to the change over time, which is liable to cause abnormal discharge. This is a well-known fact, and whether it is after long-time sputtering. There is no record of no abnormal discharge and particle generation.

Further, in the other literature (Patent Document 2) of the Cu-Ga target, a sintered body target is described, and there is a description of a related art which is prone to cracking or defect brittleness when cutting a target, and in order to solve this problem, two The powder is mixed and sintered for sintering.

One of the two powders is a powder having an increased Ga content, and the other is a powder having a reduced Ga content, which is a two-phase coexisting structure surrounded by a grain boundary phase.

In this step, since the two kinds of powders are produced, the steps are complicated, and the physical properties and the structure of the hardness of each powder are different. Therefore, it is difficult to form a uniform sintered body only by mixing and sintering, and the relative density cannot be expected to be improved.

Of course, the target with a lower density will have abnormal discharge and particles, and if there are foreign substances such as particles on the surface of the sputter film, the CIGS film characteristics will be adversely affected, and the conversion efficiency of the CIGS solar cell will eventually be greatly increased. Reduce the embarrassment.

In Patent Document 2, although sputtering using a target sputtering film is not performed, and abnormal discharge, particles, and the like are not described at all, it can be said that this problem has been implied.

In Patent Document 3, in addition to one of the materials of the recording layer of the optical recording medium, CuGa ₂ is exemplified, and the AuZn recording layer is deposited by sputtering. However, there is no description of sputtering of CuGa ₂ , but only the sputtering of CuGa ₂ is suggested.

In Patent Document 4, in addition to one of the materials of the recording layer of the optical recording medium, CuGa ₂ is exemplified, and the AuSn recording layer is deposited by sputtering. There is no description of sputtering of CuGa ₂ , but only the sputtering of CuGa ₂ is suggested.

Patent Document 5, in claim 29, describes a copper alloy target containing 100 ppm or more and less than 10% by weight of Ga, having an average crystal grain size of 1 to 20 μm, and having a crystal grain size uniformity of the entire target of less than 15%. Standard deviation. The purpose is to make the Ga concentration low and to make the target made by forging and calendering have a specific texture.

Patent Document 6 proposes a copper alloy in which an additive element containing Ga is added in a range of a solid solution limit of 0.1 to 20.0 at%. However, the examples shown in the examples are only Cu-Mn alloys, and the method for producing the targets is not specifically described, and it is considered to be obtained by a melting method. The purpose is for display devices.

Patent Document 7 is a copper alloy target obtained by subjecting a raw material component of a powder to a water pressure compression, and a method for producing a target using a mixture of indium powder and Cu-Ga alloy powder as a raw material is described in Example 3. . Compared with the invention of the present application, sintering is not performed, and the composition is also different, and there is no relevant element.

Patent Document 8 describes a sputtering target for a Cu alloy recording layer containing 1 to 20 at% Ga. However, in the examples, it is described that a material obtained by adding Zn or Mn to Cu in an arc melting furnace is used. Ingots do not have any specific records regarding the addition of a copper alloy target of Ga.

Patent Document 9 describes an example of use of a CuGa alloy target for use in 10, 20, or 30% by weight of Ga for the production of a CIGS-type thin film solar cell. However, there is no description of the method for producing the CuGa alloy target itself. . Further, the characteristics of the target are also not described in the same manner.

Patent Document 10 describes a method of producing a CuGa alloy target containing 25 to 67 at% of Ga by a forging quenching method. Although it is used for a thin film solar cell as in the present invention, it has a disadvantage unique to forging, and the problem to be solved by the invention of the present application still exists.

Patent Document 11 defines a CuGa alloy target containing 20 to 96% by weight of Ga, and in the examples, it is described that Ga25 wt% and Cu75 wt% are particularly effective. However, there is no description about the method of producing the Cu-Ga alloy target itself, and the properties of the target are also not described. In the above-mentioned patent documents, the disclosure of the subject matter of the present invention and the means for solving the same can be found.

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. 63-37834

Patent Document 4: Japanese Laid-Open Patent Publication No. 62-379533

Patent Document 5: Japanese Patent Publication No. 2005-533187

Patent Document 6: International Publication WO2006-025347

Patent Document 7: International Publication WO2007-137824

Patent Document 8: International Publication WO2007-004344

Patent Document 9: Japanese Laid-Open Patent Publication No. Hei 10-135498

Patent Document 10: Unexamined Patent No. 1719626

Patent Document 11: Japanese Patent Laid-Open No. Hei 11-260724

In view of the above circumstances, an object of the present invention is to provide a Cu-Ga alloy which has a high density in a Cu-Ga sintered body target and which has almost no abnormal discharge after sputtering for a long period of time and a particle is generated in the film. A sintered body target and a method for producing the same, and a light absorbing layer produced from a Cu-Ga alloy sintered body target, and a CIGS-based solar cell using the light absorbing layer.

In order to solve the above problems, the inventors of the present invention have worked hard to find out that abnormal discharge and particle generation are closely related to target density, and it is also known that a low-density target causes abnormal discharge and particle increase, thereby obtaining "by improvement. The average particle diameter, oxygen concentration, composition uniformity, etc. of the target can further improve the sputtering film-forming property of the Cu-Ga layer in the CIGS layer formation process, and contribute to the improvement of the conversion efficiency of the CIGS-based solar cell. this invention.

That is, the present invention provides

1) A Cu-Ga alloy sintered body sputtering target, which is characterized in that it is composed of a sintered body of a Cu-Ga alloy powder having a Ga concentration of 20 to 60 at% and a remaining portion of Cu and an unavoidable impurity. The sintered body has a relative density of 97% or more, an average crystal grain size of 5 to 30 μm, and an oxygen content of 400 ppm or less;

2) a Cu-Ga alloy sintered body sputtering target according to the above 1), wherein the Cu-Ga alloy is composed of a single composition;

The Cu-Ga alloy sintered body sputtering target according to any one of the above 1), wherein the peak intensity of the main peak other than the X-ray diffraction of the Cu-Ga alloy is 5% or less with respect to the main peak intensity;

The Cu-Ga alloy sintered body sputtering target according to any one of the above 1 to 3, wherein the Cu-Ga alloy composition is substantially a γ phase or a main phase is a γ phase.

Also, the present invention provides

5) A method for manufacturing a Cu-Ga alloy sintered body sputtering target, which comprises melting and cooling Cu and Ga raw materials, and then preparing the pulverized mixed raw material powder into a Cu-Ga alloy sputtering target by hot pressing The method is characterized in that the holding temperature during hot pressing is set to be lower than the melting point of the mixed raw material powder by 50 to 200 ° C, the holding time is set to be 1 to 3 hours, and the cooling rate is set to be 5 ° C / min or more, and the mixed raw material is mixed. The pressing pressure of the powder is set to 30 to 40 MPa for hot pressing;

6) A method for producing a Cu-Ga alloy sintered body sputtering target, wherein the Cu and Ga raw materials are melted and cooled, and then the pulverized mixed raw material powder is formed into the above 1) to 4) by a hot pressing method. The method for sputtering a target of a Cu-Ga alloy sintered body is characterized in that the holding temperature during hot pressing is set to be 50 to 200 ° C lower than the melting point of the mixed raw material powder, and the holding time is set to 1 to 3 hours. The cooling rate is set to 5 ° C / min or more, and the pressing pressure of the mixed raw material powder is set to 30 to 40 MPa for hot pressing;

7) The method for producing a Cu-Ga alloy sintered body sputtering target according to the above 5) or 6), wherein the Cu and Ga raw materials are melted and cooled and pulverized by a gas atomization method or a water atomization method.

Furthermore, the present invention provides

8) A light absorbing layer comprising the Cu-Ga alloy film produced by the Cu-Ga alloy sintered body sputtering target according to any one of the above 1) to 4);

9) A CIGS-based solar cell using the light absorbing layer of the above 8).

According to the present invention, it is possible to provide a Cu-Ga alloy which has no composition segregation in a Cu-Ga sintered body sputtering target and which has no abnormal discharge after a long time of sputtering, and which does not generate particles on the film obtained by sputtering. The sintered body target and the method for producing the same have an excellent effect of improving the production yield of the Cu-Ga film while suppressing a decrease in conversion efficiency of the CIGS solar cell produced by the Cu-Ga film.

Next, the reason for the definition of the constituent elements of the present invention, the reason, the meaning, the adjustment method, the measurement method, and the like are described.

The Cu-Ga alloy sintered body sputtering target of the present invention has a Ga concentration in the range of 20 to 60 at%, and the remainder is Cu and unavoidable impurities. This is because of the appropriate and preferred Ga concentration range for the actual production of CIGS-based solar cells. However, the technical idea of the present invention itself can also be applied to components outside this range.

The most important requirement of the Cu-Ga alloy sintered body sputtering target is to set the relative density of the sintered body to 97% or more. The relative density is the ratio of the actual absolute density of the sintered body target divided by the value of the theoretical density of the target.

The fact that the relative density of the target is low means that a large number of internal pores are present in the target. Therefore, when internal pores appear in the sputtering, splashing and abnormal discharge starting from the periphery of the pores are likely to occur.

Therefore, the occurrence of particles in the film is increased, and the unevenness of the surface progresses early, and it is easy to cause abnormal discharge or the like starting from a surface protrusion (nodule). This is one of the reasons for the reduced conversion efficiency of CIGS solar cells. Therefore, the relative density of the sintered body target must be at least 97%, preferably 98% or more, more preferably 99% or more.

Further, the Cu-Ga alloy sintered body sputtering target system of the present invention has an average crystal grain size of 5 to 30 μm. The average particle size may be slightly etched as needed, and the grain boundaries may be determined and then determined by a planimetric method.

When the average particle diameter of the sintered body target is small, there is an advantage that the density can be increased. Further, when the average particle diameter is large, the crystal grains are randomly aligned, and therefore the sputtering rate varies depending on the crystal plane orientation. Therefore, it is easy to cause large unevenness on the surface, and it is easy to increase the generation of particles as a starting point. Therefore, by making the average particle diameter small, the density of the target can be increased, and the number of particles generated can be further reduced.

From the above mechanism, it is advantageous to make the average crystal grain size of the target as small as about 5 to 30 μm. However, in the case where the average particle diameter is less than 5 μm, it is disadvantageous in practical use because the steps must be increased in manufacturing. Therefore, the lower limit of the average crystal grain size was set to 5 μm.

In addition, when the average particle diameter exceeds 30 μm, the effect of increasing the density is reduced, and the number of particles is increased. Therefore, it is preferably 30 μm or less.

The average particle size can be adjusted according to the temperature at which the pressure is maintained during hot pressing, and the higher the temperature, the larger the particle size. Further, although it may further exceed 30 μm, or even a larger 50 μm or more, it is not preferable because the density is lowered as a whole.

The oxygen content was set to 400 ppm or less as a condition of the Cu-Ga alloy sintered body sputtering target of the present invention. If the oxygen concentration is high, it is easy to combine with the metal component of the Cu-Ga alloy to form an oxide. Further, since the oxide resistance is higher than that of the metal, it exceeds the degree of unevenness of the resistance of the single composition, so that a difference in resistance occurs in the target surface, and abnormal discharge and sputtering speed starting from the high resistance portion are liable to occur. The surface irregularities are likely to cause abnormal discharge and particle generation.

When mechanical pulverization is performed in an atmospheric environment, the oxygen concentration tends to increase. When the oxygen content becomes high, the pulverized powder must be subjected to reduction treatment.

Conversely, if the mechanical pulverization, the water atomization method, or the gas atomization method are carried out in an environment containing no oxygen, the oxygen concentration can be reduced. Therefore, in order to further reduce oxygen, it is preferred to use a water atomization method or a gas atomization method, and it is preferred to carry out a reduction treatment as needed.

One of the preferable conditions for the Cu-Ga alloy sintered body sputtering target of the present invention is to provide a Cu-Ga alloy sintered body sputtering target composed of a single composition of a Cu-Ga alloy.

The term "single composition" in the present invention is used in the sense of "a composition consisting of a composition in which other components cannot be detected by a usual physical means". Further, at the microscopic level, even if a trace amount of other components is not considered to adversely affect various characteristics, substantially the same effect as a single composition is exhibited.

One of the preferable conditions of the Cu-Ga alloy sintered body sputtering target of the present invention is to provide a Cu-Ga alloy sintered body sputtering target, wherein the peak intensity of the Cu-Ga alloy other than the main peak of the X-ray diffraction is relative to The main peak intensity is 5% or less.

The basis of the singularity can be defined by the X-ray peak intensity ratio. The peak intensity of the other components is substantially the same as the single composition as long as it is 5% or less as compared with the peak of the main composition.

The composition of the mixed raw material powder produced by gas atomization or water atomization is substantially uniform, and the target composition obtained by hot pressing the mixed raw material can be nearly uniform. Further, if the cooling rate is small during hot press cooling, a hetero phase may be precipitated during cooling. If such a heterogeneous amount is large, it can be detected by an X-ray diffraction peak.

The Cu-Ga alloy has a Gamma (γ) phase when the Ga composition is about 30 to 43 at%. This phase is brittle and has the characteristics of being easily broken. Most of the Cu-Ga compositions used in CIGS-based solar cells are particularly in this Ga concentration range. In order to avoid the brittleness of such a Cu-Ga alloy, it is particularly effective to increase the density.

Next, the reason and meaning of the scoping, the influence on the characteristics of the target, and the like will be described with respect to the method for producing the target of the present invention.

The Cu and Ga raw materials are weighed in a predetermined composition ratio, placed in a carbon crucible, and heated in a heating furnace pressurized to about 0.5 MPa atmosphere to a melting point of about 50 to 200 ° C to melt the mixed raw material. After maintaining the molten raw material sufficiently for about 1 hour or more, the heating is stopped, and after cooling, the primary synthetic raw material is taken out.

This primary synthetic raw material is pulverized to obtain a fine powder raw material. The pulverization method includes mechanical pulverization, gas atomization method, water atomization method, etc., and any method is acceptable, but the method of water atomization is low in cost and can be processed in a large amount.

In the case of water atomization, the method is as follows: the primary synthetic raw material is once again melted in a crucible, and a liquid material is dropped, and about 10 Mpa of high pressure water is sprayed on the dripping liquid to obtain a fine powder. The obtained fine powder is used after being subjected to pressure filtration, drying, or the like as a raw material for mixing fine powder.

The mixed fine powder raw material is passed through a sieve of a specific opening, the particle size distribution is adjusted, and hot pressing is performed. The hot pressing conditions differ depending on the Ga concentration. For example, when the Ga concentration is 30 at%, the temperature is 600 to 700 ° C and the pressure is 30 to 40 MPa.

That is, in terms of the preferable conditions of the hot pressing, the effective ones are as follows: the temperature at which the hot pressing is maintained is lower than the melting point of the mixed raw material powder by 50 to 200 ° C, the holding time is set to 1 to 3 hours, and the cooling rate is set to 5 ° C. Above /min, the pressure of the mixed raw material powder is set to 30 to 40 MPa. When this hot pressing condition is appropriately selected, the density of the Cu-Ga alloy target can be increased.

In terms of the relationship between the temperature profile such as the temperature increase rate and the holding time and the pressure application profile, the pressure is applied first before the pressure is applied to the highest temperature and then the pressure is applied. The powder will be finer and finer, which is effective for increasing the sintered density.

Further, if the cooling rate of the hot pressing is slow, a phase difference occurs between them, so that a rapid temperature at which the cooling rate is 5 ° C/min or more is effective.

The density of the Cu-Ga sintered body produced by the above method can be obtained by the Archimedes method, the average particle diameter can be obtained by surface etching, the plane method, the oxygen concentration can be ICP analysis, and the composition can be obtained by X-ray diffraction.

The Cu-Ga sintered body can be processed into, for example, a diameter of 6 吋 and a thickness of 6 mm, and then indium is attached to a backing plate as a brazing filler metal as a sputtering target, and then a film is formed. Investigate the state of particle formation, ball formation, and abnormal discharge of the membrane.

Example

Next, examples and comparative examples of the present invention will be described. In addition, since the following examples are representative of representative examples, the present invention is not necessarily limited to the embodiments, and should be construed in the scope of the technical idea described in the specification.

(Example 1)

The Cu raw material and the Ga raw material were weighed so that the Ga concentration of the composition was 30 at%, placed in a carbon crucible, melted at 1000 ° C in a heating furnace to which 0.5 Mpa of argon was applied, and then cooled at a rate of 5 to 10 ° C/min. After cooling, the synthetic raw materials were taken out.

Next, this synthetic raw material was placed in a carbon crucible of a water atomizing apparatus, and after melting at 1000 ° C, the molten liquid was dropped while a high pressure water of 10 MPa was sprayed on the dropping liquid to obtain a Cu-Ga mixed fine powder. The mixed fine powder was filtered under pressure and dried at 120 ° C to obtain a mixed fine powder raw material.

After the mixed fine powder was heated from room temperature to 650 ° C at a temperature elevation rate of 5 ° C / min, it was kept at 650 ° C for 2 hours while applying a pressure of 35 MPa. Thereafter, the mixture was cooled at a temperature drop rate of 5 ° C/min, and then the sintered body was taken out.

The obtained Cu-Ga sintered body had a relative density of 99.9%, an average particle diameter of 5 μm, an oxygen content of 350 ppm, and an X-ray diffraction peak intensity ratio of the main phase and the heterophase of 0.2%. This sintered body was processed into a disk shape having a diameter of 6 吋 and a thickness of 6 mm to form a sputtering target and sputtering. The sputtering power was 1000 W for direct current (DC), argon for ambient gas, 50 sccm for gas flow, 0.5 Pa for pressure at the time of sputtering, and a glass substrate of Corning 1737 having a diameter of 4 吋 and a thickness of 0.7 mm for the substrate.

After the sputtering time of 20 hours, the total sputtering amount was 20 kWhr, and the number of particles of 0.2 μm or more which was formed in the film when the Cu-Ga film thickness was formed by a microscope for 30 minutes was counted by a microscope, and was found to be 0. Further, no abnormal discharge was observed at the time of film formation. The above results are shown in Table 1.

(Examples 2 to 6)

The target in which the Ga composition and the average particle diameter were changed was prepared in the same manner as in Example 1, and the results of the sputtering evaluation were collectively shown in Table 1.

As shown in Table 1, the Ga concentrations of Examples 2 to 6 were in the range of 30 to 42 at%, the average particle diameter was 12 to 26 μm, and the oxygen content was in the range of 360 to 400 ppm.

Further, the average crystal grain size can be appropriately adjusted by adjusting the sintering temperature, pressure, and cooling rate. Further, the oxygen content can be controlled by adjustment of the melting atmosphere of the raw material. As long as the crystal grain size of the sintered body is fine, the density tends to be high.

As shown in Table 1, the relative densities of Examples 2 to 6 were in the range of 99.8 to 97.5%, the X-ray intensity ratio was in the range of 0.3 to 1.2%, and the number of particles was in the range of 0 to 8, and no abnormal discharge occurred. In addition, in Table 1, the case where there is no abnormal discharge is described as "None", the case of 1 to 10 times is described as "less", and the case where it is more than 10 times is described as "more".

From Table 1, it can be understood that sputtering of Ga composition and a target having a specific particle diameter within a specific range does not cause abnormal discharge, and almost no particle is generated, which is a good result. Although the main reason for these factors is greatly affected by the oxygen concentration, it is also affected by the average crystal grain size and density of the sintered body. This tendency is clear from the comparison with the comparative examples shown below.

(Comparative Example 1 to Comparative Example 2)

Although the target was produced under substantially the same conditions as in Example 1, the melting atmosphere of the raw material was changed to oxygen more than the conditions of the examples. Therefore, the oxygen of the sintered body target is more than that of the present invention. Further, by making the temperature at the time of hot pressing lower than the temperature of the example, the density was slightly lower than that of the example. The properties of the target and the results of the sputtering are as described in Table 1.

The amounts of the particles of Comparative Example 1 and Comparative Example 2 were slightly increased as compared with the examples, and although abnormally generated, abnormal discharge occurred in the film formation.

From this result, it is understood that if the oxygen content is increased beyond the range of the present invention, the particle and the discharge state are deteriorated.

(Comparative Example 3 to Comparative Example 5)

Although the target was produced under substantially the same conditions as in Comparative Examples 1 and 2, the amount of oxygen was further increased to 450 ppm as compared with Comparative Examples 1 and 2. Further, in Comparative Example 3, the hot pressing temperature was 700 ° C, and the cooling rate after hot pressing was 2 ° C / min. In Comparative Example 4, the hot pressing temperature was 650 ° C, and the cooling rate after hot pressing was 4 ° C / min. Further, Comparative Example 5 was heat. The pressure was 750 ° C, and the cooling rate after hot pressing was 1 ° C / min to prepare a target having a slightly larger average particle diameter and a larger X-ray intensity ratio, and confirming some micro phase.

The characteristics of the target and the results of the sputtering are shown in Table 1. In Comparative Example 3, although the abnormal discharge was small, the amount of particles was slightly larger.

In Comparative Example 4 and Comparative Example 5, the amount of particles was further increased, and the amount of abnormal discharge was also large. This is considered to be the effect of an increase in oxygen content.

(Comparative Example 6 to Comparative Example 8)

Although the target was produced under substantially the same conditions as in Comparative Examples 3 to 5, the amount of oxygen was further increased as compared with Comparative Examples 3 to 5. The oxygen amount of Comparative Example 6 and Comparative Example 7 was 470 ppm, and the oxygen amount of Comparative Example 8 was 480 ppm.

The characteristics of the target and the sputtering results are shown in Table 1. The amounts of the particles of Comparative Examples 6 to 8 increased, and the abnormal discharge was also large. It is considered to be the effect of an increase in oxygen.

(Comparative Example 9 to Comparative Example 10)

The amount of oxygen further increased in comparison with Comparative Examples 3 to 5 under substantially the same conditions as in Comparative Examples 3 to 5. The amount of oxygen in Comparative Example 9 was 600 ppm, and the amount of oxygen in Comparative Example 10 was 1300 ppm.

The characteristics of the target and the sputtering results are shown in Table 1. The amounts of the particles of Comparative Examples 9 to 10 were further increased, and the abnormal discharge was also large. This is considered to be the effect of an increase in oxygen.

(Comparative Example 11 to Comparative Example 13)

The amount of oxygen was lower than that of Comparative Examples 3 to 5, but the average crystal grain size was large, and the X-ray intensity ratio was as high as 4.6 to 11.0. In Comparative Example 11 and Comparative Example 12, the abnormal discharge was small, but Comparative Examples 11 to 13 each had a number of particles of 15 to 21. From the above, it was confirmed that the coarsening of the average crystal grain size and the increase in the X-ray intensity ratio also affect the increase in abnormal discharge.

(Comparative Example 14 to Comparative Example 16)

A Cu-Ga target was produced by a melting method. The Cu and Ga raw materials were weighed so that the Ga composition was a predetermined concentration and placed in a carbon crucible, and supplied to an aerobic heating furnace in an argon atmosphere. Comparative Example 14 was higher at 1000 ° C, Comparative Example 12, and Comparative Example 13 The melting point of the material was melted at about 200 ° C, and then cooled and cooled at a cooling rate of about 5 ° C / min. The properties of the extract were evaluated, and then processed to form a sputtering target, and then film formation evaluation was performed.

The results are shown in Table 1. From this result, it is understood that although the amount of oxygen can be greatly reduced, the average crystal grain size is as high as 1,100 to 830 μm. Also, the X-ray intensity ratio is also significantly increased. Further, the relative density of Comparative Example 16 was also lower than the conditions of the present invention.

As a result, the number of particles increases, and the abnormal discharge also increases. Therefore, when the average particle diameter is increased and the X-ray intensity ratio is increased, the particles and the discharge state are further deteriorated.

(Comparative Example 17 to Comparative Example 18)

Although they were substantially the same conditions as Comparative Examples 3 to 5, only the relative density was lower than the present invention, and the conditions of the present invention were not satisfied. In Comparative Example 17, it was found that the number of pores was large. Further, in Comparative Example 18, shrinkage cavities were observed. These all have an impact on the density reduction.

As a result, the amounts of the particles of Comparative Example 17 to Comparative Example 18 were further increased, and the abnormal discharge was also increased. From the above, it can be understood that the decrease in relative density adversely affects the amount of particles and abnormal discharge.

In the above examples, the Ga concentration was in the range of 30.0 to 42.6 at%, and the effects of the relative density, the average crystal grain size, and the oxygen content were confirmed. The Ga concentration was 20 to 60 at%, and the remainder was Cu and could not be avoided. The sintered body of the Cu-Ga alloy powder of the impurity also exhibits the same tendency.

Therefore, the present invention is all applicable to a sintered body sputtering target of a Cu-Ga alloy powder having a Ga concentration of 20 to 60 at% and a remaining portion of Cu and an unavoidable impurity, as long as it is in the technical field of the present invention. Usually the knowledge is easy to understand.

(industrial availability)

According to the present invention, it is possible to provide a Cu-Ga sintered body sputtering target which has no compositional segregation and no abnormal discharge after sputtering for a long period of time, and a Cu-Ga sintered body target which hardly generates particles in the film obtained by sputtering. Since the target is used, a good Cu-Ga film can be produced by using the target, and in particular, it can be used as a material for manufacturing a CIGS-based solar cell using a selenization method.

Claims (10)

A Cu-Ga alloy sintered body sputtering target characterized in that it is composed of a sintered body of a Cu-Ga alloy powder having a Ga concentration of 20 to 60 at% and a remaining portion of Cu and an unavoidable impurity, the sintering The relative density of the body is 97% or more, the average crystal grain size is 5 to 30 μm, and the oxygen content is 400 ppm or less. A Cu-Ga alloy sintered body sputtering target according to claim 1, wherein the Cu-Ga alloy is composed of a single composition. The Cu-Ga alloy sintered body sputtering target according to claim 1 or 2, wherein the peak intensity other than the main peak of the X-ray firing of the Cu-Ga alloy is 5% or less with respect to the main peak intensity. A Cu-Ga alloy sintered body sputtering target according to claim 1 or 2, wherein the Cu-Ga alloy composition is substantially a γ phase or a main phase is a γ phase. A Cu-Ga alloy sintered body sputtering target according to claim 3, wherein the Cu-Ga alloy composition is substantially a γ phase or a main phase is a γ phase. A method for producing a Cu-Ga alloy sintered body sputtering target, which comprises melting and cooling Cu and Ga raw materials, and then hot-pressing the pulverized mixed raw material powder to produce a Cu-Ga alloy sintered body by hot pressing The method for sputtering a target is characterized in that the holding temperature during hot pressing is set to be 50 to 200 ° C lower than the melting point of the mixed raw material powder, the holding time is set to 1 to 3 hours, and the cooling rate is set to be 5 ° C / min or more. The pressing pressure of the mixed raw material powder is set to 30 to 40 MPa for hot pressing. Method for manufacturing Cu-Ga alloy sintered body sputtering target, which will be After the Cu and Ga raw materials are melted and cooled, the pulverized mixed raw material powder is hot-pressed by hot pressing to produce a Cu-Ga alloy sintered body sputtering target according to any one of claims 1 to 5. The method is characterized in that: the holding temperature during hot pressing is set to be lower than the melting point of the mixed raw material powder by 50 to 200 ° C, the holding time is set to be 1 to 3 hours, and the cooling rate is set to be 5 ° C / min or more, and the mixed raw material powder is selected. The pressing pressure is set to 30 to 40 MPa for hot pressing. A method for producing a Cu-Ga alloy sintered body sputtering target according to claim 6 or 7, wherein the Cu and Ga raw materials are melted and cooled after being cooled by a gas atomization method or a water atomization method. A light absorbing layer obtained by a Cu-Ga alloy sintered body sputtering target according to any one of claims 1 to 5. A CIGS-based solar cell using the light absorbing layer of claim 9 of the patent application.