KR20130110107A - Cu-ga alloy sputtering target and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A Cu-Ga alloy sputtering target and a manufacturing method thereof are provided to reduce gas component, such as oxygen compared to a pellet target, to reduce oxygen, and to also obtain the target in which dendrite is dispersed and which has a high-quality cast structure. CONSTITUTION: A Cu-Ga alloy sputtering target has a structure consisting of α phase in which Ga is employed in Gu or the mixed phase with α phase and ζ phase, and is formed with dendrite structure dispersed to the α phase or the mixed structure with α phase and ζ phase. The dendrite structure consists of a first arm and a second arm grown in a side direction from the first arm. The average length of the second arm is 30 to 60 μm, the average width of the second arm is 10 to 30 μm, and the average distance between the second arms is 20 to 80 μm. The maximum diameter of the first arm is 5 to 30 μm. [Reference numerals] (AA) First arm; (BB) Width of a second arm; (CC) Length of a second arm; (DD) Second arm; (EE) Space between second dendrite arms; (FF) Structure of a dendrite

Description

Cu-Ga alloy sputtering target and its manufacturing method {Cu-Ga ALLOY SPUTTERING TARGET AND METHOD FOR MANUFACTURING THE SAME}

The present invention relates to a Cu-Ga alloy sputtering target used when forming a Cu-In-Ga-Se (hereinafter referred to as CIGS) quaternary alloy thin film which is a light absorbing layer of a thin film solar cell layer, and a method of manufacturing the same.

In recent years, mass production of highly efficient CIGS-based solar cells has progressed as thin-film solar cells, and vapor deposition and selenization are known as methods for producing the light absorption layer. Although the solar cell manufactured by the vapor deposition method has the advantage of high conversion efficiency, there are disadvantages of low film rate, high cost, and low productivity, and the selenization method is suitable for industrial mass production.

The outline process of the selenization method is as follows. First, a molybdenum electrode layer is formed on a soda-lime glass substrate, a Cu-Ga layer and an In layer are sputter-formed thereon, and a CIGS layer is formed by high temperature treatment in selenium hydride gas. A Cu-Ga target is used at the time of sputtering the Cu-Ga layer during the CIGS layer forming process by the selenization method.

The conversion efficiency of the CIGS-based solar cell affects various manufacturing conditions, the properties of the constituent materials, and the like, but also significantly affects the characteristics of the CIGS film.

As a manufacturing method of a Cu-Ga target, there exist a dissolution method and a powder method. In general, the Cu-Ga target produced by the dissolution method is considered to have relatively low impurity contamination, but also has many drawbacks. For example, since the cooling rate can not be increased, the composition of the film produced by the sputtering method is gradually changed due to large compositional segregation.

In addition, shrinkage pores tend to occur in the final stage during the cooling of the molten metal, and the portion around the shrinkage pores is also poor in properties, and the yield is poor because it cannot be used in terms of convenience in processing into a predetermined shape.

Prior literatures (Patent Document 1) on Cu-Ga targets by the dissolution method describe the fact that no composition segregation was observed, but the analysis results and the like are not shown at all.

In the examples, only the Ga concentration is 30% by weight, and there is no description regarding the characteristics of the structure, segregation, etc. in the Ga low concentration region.

On the other hand, the target produced by the powder method generally had problems, such as low sintering density and high impurity concentration. Although Patent Document 2 on Cu-Ga targets describes a sintered compact target, there is a description of the prior art regarding brittleness that cracks and defects are likely to occur when cutting a target, and two types of Powder is prepared, this is mixed and sintered. One of the two kinds of powders is a powder having a high Ga content, and the other is a powder having a low Ga content, which is used as a two-phase coexistence structure surrounded by grain boundaries.

Since this process produces two kinds of powders, the process is complicated, and the metal powder has a high oxygen concentration, so that the relative density improvement of the sintered compact cannot be expected.

A target with a low density and a high oxygen concentration naturally has abnormal discharges and particles, and if there is a release product such as particles on the surface of the sputter film, it adversely affects subsequent CIGS film properties, and finally, conversion of the CIGS solar cell. There is much concern that it will cause the big fall of efficiency.

The big problem of the Cu-Ga sputtering target produced by the powder method is that the process is complicated, the quality of the produced sintered compact is not necessarily good, and there is a big disadvantage that the production cost increases. Although the melting and casting method is preferable at this point, there exists a manufacturing problem as mentioned above and the quality of the target itself was not able to be improved.

As a conventional technique, there is, for example, Patent Document 3. In this case, the technique which processes this into a target by continuous casting the copper alloy which added high purity copper and 0.04 to 0.15 weight% of trace titanium, or 0.014 to 0.15 weight% of zinc is described.

Such an alloy is not applicable to the production of an alloy with a large amount of additional elements because the amount of additional elements is very small.

Similarly, Patent Document 4 discloses a technique in which high-purity copper is continuously cast so as not to have a casting defect in a rod shape, which is rolled and processed into a sputtering target. This is a handling in pure metals and is not applicable to the production of alloys with a large amount of added elements.

Patent Document 5 describes that a material selected from 24 elements such as Ag and Au is continuously added to aluminum to continuously cast to produce a single crystallized sputtering target. Similarly, since the alloy has a small amount of additional elements, the alloy is not applicable to the production of an alloy with a large amount of additional elements.

Although the examples which manufacture using the continuous casting method are shown about the said patent documents 3-5, all are added to the material of a pure metal or a trace element addition alloy, and there are many additive elements, and Cu tends to generate segregation of an intermetallic compound. It can be said that the disclosure does not solve the problems present in the production of the -Ga alloy target.

Japanese Laid-Open Patent Publication 2000-73163 Japanese Unexamined Patent Publication No. 2008-138232 Japanese Patent Laid-Open No. 5-311424 Japanese Laid-Open Patent Publication 2005-330591 Japanese Laid-Open Patent Publication No. 7-300667

In the Cu-Ga alloy containing 15 at% or more of Ga, segregation of the intermetallic compound is likely to occur, and it is difficult to disperse the segregation finely and uniformly by the usual dissolution method. On the other hand, the sputtering target of a cast structure has the advantage that gas components, such as oxygen, can be reduced compared with the sintered compact target. It is a subject to obtain the target of the high quality cast structure which reduced oxygen and disperse | distributed the segregation phase by solidifying the sputtering target which has this casting structure continuously in the solidification conditions more than a fixed cooling rate.

In order to solve the above-mentioned problems, the present inventors have conducted a thorough study, and as a result, the present inventors have found that a CuGa alloy sputtering target of a high quality cast structure in which oxygen is reduced and a large number of resinous phases are dispersed by a continuous casting method It was found that it could be obtained, and completed the present invention.

From the said knowledge, this invention provides the following invention.

1) Ga-based α- or α- and ζ-phase in which Ga is dissolved in Cu as a plate-shaped Cu-Ga alloy sputtering target in which Ga is 15 at% or more and 22 at% or less, and the balance is composed of Cu and unavoidable impurities. The dendrite structure is dispersed in a structure composed of a mixed phase, and composed of the α phase or a mixed phase of the α phase and the ζ phase, and the dendrite structure (resin phase crystal) is laterally separated from the primary arm and the primary arm. It consists of the grown secondary arm, The average length of a secondary arm is 30-60 micrometers, The average width of a secondary arm is 10-30 micrometers, The mean space | interval between the secondary arms is 20-80 micrometers, It is characterized by the above-mentioned. Cu-Ga alloy sputtering target.

2) The maximum diameter of a primary arm is 5-30 micrometers, The Cu-Ga alloy sputtering target as described in said 1) characterized by the above-mentioned.

3) The Cu-Ga alloy sputtering target according to 1) or 2) above, wherein the secondary arm of the dendrites has a Ga concentration that is thicker than that of the dendrites.

4) The Cu-Ga alloy sputtering target according to 3) above, wherein the Ga concentration is higher than that of the dendrite structure, which is an α phase or a ζ phase.

5) Oxygen content is 20 wtppm or less, The Cu-Ga alloy sputtering target in any one of said 1) -4) characterized by the above-mentioned.

6) The target raw material is dissolved in a crucible made of graphite, and the molten metal is poured into a mold provided with a water-cooled probe to continuously manufacture a plate-shaped casting made of a Cu-Ga alloy, which is further machined to form a plate-shaped Cu A method for producing a -Ga alloy target, wherein the solidification rate from the melting point of the cast body to 300 ° C. is controlled at 300 to 1000 ° C./min, wherein the Cu-Ga alloy sputtering target is produced.

7) The target raw material is dissolved in a crucible made of graphite, and the molten metal is poured into a mold provided with a water-cooled probe to continuously manufacture a plate-shaped casting made of a Cu-Ga alloy, which is further machined to form a plate-shaped Cu A method for producing a -Ga alloy target, wherein the target according to any one of 1) to 6) above is controlled by controlling the solidification rate from the melting point of the cast body to 300 ° C at 300 to 1000 ° C / min. The manufacturing method of the Cu-Ga alloy sputtering target characterized by the above-mentioned.

8) The manufacturing method of the Cu-Ga alloy sputtering target as described in said 6) which manufactures with drawing speed as 50 mm / min-150 mm / min.

9) The manufacturing method of the Cu-Ga alloy sputtering target as described in said 6) or 7) manufactured using the horizontal continuous casting method.

10) By controlling the solidification rate from the melting point of the cast to 300 ℃ to 300 ~ 1000 ℃ / min, to adjust the amount and concentration of the α phase or the mixed phase of the α phase and ζ phase formed during casting The manufacturing method of the Cu-Ga alloy sputtering target in any one of said 6) -9) characterized by the above-mentioned.

According to the present invention, there is a great advantage that the gas component such as oxygen can be reduced in comparison with the sintered compact target, and the oxygen is reduced by solidifying the sputtering target having this cast structure continuously under the solidification conditions at a constant cooling rate, Moreover, it has the effect that the target of the quality casting structure which disperse | distributed the dendrite can be obtained.

By sputtering using a Cu-Ga alloy target having a cast structure with less oxygen and segregation dispersed in this way, it is possible to obtain a homogeneous Cu-Ga-based alloy film with less generation of particles and a Cu-Ga alloy target. Has the effect of greatly reducing the manufacturing cost. Since the light absorption layer and the CIGS solar cell can be manufactured from such a sputter film, the fall of the conversion efficiency of a CIGS solar cell is suppressed and it has the outstanding effect that a low cost CIGS solar cell can be manufactured.

1 is a conceptual explanatory diagram of a dendrite structure.
It is a figure which shows the micrograph of the surface which etched the target grinding | polishing surface of Example 1, 2, 3, 4 and Comparative Examples 1, 2 with the hydrochloric acid solution containing ferric chloride.
3 is a diagram showing the results of surface analysis of FE-EPMA for the target polishing surfaces of Example 2 (upper view) and Example 4 (lower view).

The Cu-Ga alloy sputtering target of the present invention is a plate-shaped Cu-Ga alloy sputtering target in which Ga is 15 at% or more and 22 at% or less and the balance is made of Cu and unavoidable impurities.

Generally, the sintered product is intended to have a relative density of 95% or more. When the relative density is low, when the internal voids in the sputter are exposed, particle generation and surface unevenness advance to the film due to splashes or abnormal discharges starting from the periphery of the voids. It is because abnormal discharge etc. which originate from a nodule) tend to occur. The cast product can achieve almost 100% relative density, and as a result, the difference in sputtering has the effect of suppressing generation of particles. This is one of the great advantages of casting.

Although content of Ga is needed by the request of formation of the Cu-Ga alloy sputtering film | membrane which is needed when manufacturing a CIGS system solar cell, the Cu-Ga alloy sputtering target of this invention is Ga 15-at least 22 at% Hereinafter, the remainder is a plate-shaped Cu-Ga alloy sputtering target made of Cu and unavoidable impurities.

And the plate-shaped Cu-Ga alloy sputtering target melt | dissolved and cast has the structure which consists of the alpha phase which Ga dissolved in Cu, or the mixed phase of alpha phase and ζ phase. Further, dendrite (resin-supposing) tissue is dispersed in this tissue, and the dendrite tissue is composed of a primary arm and a secondary arm laterally grown from the primary arm. The average length of a secondary arm is 30-60 micrometers, the average width of a secondary arm is 10-30 micrometers, and the average space | interval between the secondary arms is 20-80 micrometers.

The conceptual explanatory diagram of a dendrite structure is shown in FIG. As shown in FIG. 1, a primary arm exists in the center and a secondary arm grows in the side. The length of a secondary arm means the length from the side wall of a primary arm to a tip, and the width of a secondary arm means the width of the arm as shown in FIG. Spacing of the secondary arms means the spacing between the central axes of the secondary arms.

Thus, the dendrite structure (resin phase) uniformly dispersed is very effective for the formation of a film. The dendrites are affected by the cooling rate, and when the cooling rate is high, the fine dendrites (resin phase) grow rapidly. Since Ga is an element that lowers the melting point, Ga content is small in the dendrite structure at first. That is, the dendrite structure with little Ga content is formed. Thereafter, between the secondary arms of the dendrite structure, a Ga concentration richer in Ga concentration than the dendrites is formed.

The Ga concentration rich in Ga concentration is a segregation phase, but since the dendrite structure (resin phase) is dispersed finely, the Ga concentration phase formed between the dendrite structures is similarly fine. The result is dispersion. This is one of the great features of the present invention. When observing the whole structure of a sputtering target, it turns out that there is no big segregation and it is a uniform structure.

Moreover, as one of the characteristics of the dendrite structure of this invention, the largest diameter of a primary arm is 5-30 micrometers. This also means the characteristic of the form in which the dendrite structure (resin assumption) is dispersed finely.

The Ga concentration higher than the dendrite structure is characterized in that the α phase or the ζ phase which is a solid solution. The Cu-Ga alloy sputtering target of this invention is low in oxygen content comprehensively, and can provide the Cu-Ga alloy sputtering target of 20 wtppm or less.

In the manufacturing method of a Cu-Ga alloy sputtering target, a target raw material is melt | dissolved in the crucible made from graphite, this molten metal is poured into the mold provided with a water-cooled probe, and it continuously manufactures the plate-shaped casting body which consists of Cu-Ga alloy, This is further machined to produce a plate-shaped Cu-Ga alloy target, and it is preferable to control the solidification rate from the melting point of the cast body to 300 ° C at 300 to 1000 ° C / min. Thereby, said target can be manufactured.

Moreover, as an efficient and effective means of manufacture of a Cu-Ga alloy sputtering target, it is preferable to make drawing speed into 50 mm / min-150 mm / min. Moreover, it is effective to manufacture such a continuous casting method using the horizontal continuous casting method.

In this way, by controlling the solidification rate from the melting point of the cast body to 300 ° C. at 300 to 1000 ° C./min, the amount and concentration of the α phase or the mixed phase of the α phase and ζ phase formed at the time of casting are easy. Can be adjusted.

As described above, the Cu-Ga alloy sputtering target of the present invention can have an oxygen content of 20 wtppm or less, but this is to prevent degassing of the Cu-Ga alloy molten metal and atmospheric mixing measures (for example, And the introduction of argon gas or nitrogen gas in the seal portion.

This is a preferable requirement for improving the characteristic of a CIGS system solar cell similarly to the above. Moreover, by this, generation | occurrence | production of the particle at the time of sputtering can be suppressed, oxygen in a sputtering film can be reduced, and it has the effect which can suppress formation of the oxide or suboxide by internal oxidation.

In the production of the Cu-Ga alloy sputtering target, a cast body having a width of 50 mm to 320 mm and a thickness of 5 mm to 30 mm in the cross section of the cast body drawn out from the mold is manufactured, machined and surface polished It can finish with a target, and although this manufacturing condition is arbitrary, it can be called preferable conditions.

In the fabrication of a light absorbing layer and a CIGS-based solar cell made of a Cu-Ga-based alloy film, the variation in composition greatly changes the characteristics of the light-absorbing layer and the CIGS-based solar cell, but the Cu-Ga alloy sputtering target of the present invention is used. In the case of film formation, no such composition deviation is observed at all. This is one of the major advantages of castings over sintered parts.

Example

Next, the Example of this invention is described. In addition, this embodiment is an example to the last, It is not limited to this example. That is, the present invention includes all aspects and modifications other than the invention and examples which can be grasped from the entire specification within the scope of the technical idea of the present invention.

(Example 1)

First, 20 kg of copper (Cu: purity 4N) raw materials were put into a carbon crucible, the inside of the crucible was made into nitrogen gas atmosphere, and it heated to 1250 degreeC. This high temperature heating is for welding a dummy bar and molten Cu-Ga alloy.

Next, Ga (purity: 4N) which is an additional element was adjusted so that it might become a composition ratio whose Ga concentration is 15 at%, and it introduce | transduced into the heating crucible. A resistance heating device (graphite element) was used for heating the crucible. The shape of the melting crucible was 140 mmφ × 400 mmφ, the material of the mold was made of graphite, and the shape of the cast mass was continuously cast as a 65 mm w × 12 mmt plate.

After the raw material is dissolved, the molten metal temperature is lowered until it reaches 1080 ° C, and drawing is started when the molten metal temperature and the mold temperature are stabilized. Since the dummy bar is inserted in the front end of the mold, the solidified casting piece is taken out by pulling out the dummy bar.

The drawing pattern was repeated with 0.5 second drive and 2.5 second stop, the frequency was changed, and the drawing speed was 50 mm / min. The drawing speed (mm / min) and the cooling rate (° C / min) are proportional to each other. When the drawing speed (mm / min) is increased, the cooling rate also increases. As a result, it became the cooling rate of 350 degreeC / min.

The obtained cast piece had a structure in which Ga was dissolved in Ga (α phase), the oxygen concentration was less than 10 wtppm, and fine dendrite structures were formed. The secondary dendrite arm spacing was 37 µm, the length of the secondary dendrites was 38 µm, and the width was 24 µm.

In addition, the space | interval and the dimension of the secondary arm of a dendrite are the average value measured 5 points from five dendrites selected at random, respectively. Therefore, the average number of secondary arms = 25 selected for the number of dendrites 5x is measured. Hereinafter, the same applies.

Between secondary dendrite arms, a phase with high Ga concentration (segregation phase, abnormal phase) was observed. Since this is a structure sandwiched between secondary dendride arms, the dendrite structure is formed finely, and thus the segregation phase (above) was also uniformly dispersed.

The results are shown in Table 1. Next, the photomicrograph of the surface which machined this casting piece into target shape, grind | polishing further, and the grinding | polishing surface etched with the hydrochloric acid solution containing ferric chloride is shown in FIG. As a result, a cast structure in which the Ga phase (segregation phase) was uniformly dispersed could be obtained. Thus, sputtering using the Cu-Ga alloy target which has a small amount of oxygen and the cast structure which Ga phase (segregation phase) disperse | distributed uniformly was produced, and the particle | grains generate | occur | produced little and the homogeneous Cu-Ga type alloy film was obtained.

(Example 2)

First, 20 kg of copper (Cu: purity 4N) raw materials were put into a carbon crucible, the inside of the crucible was made into nitrogen gas atmosphere, and it heated to 1250 degreeC. This high temperature heating is for welding a dummy bar and molten Cu-Ga alloy.

Next, Ga (purity: 4N) which is an additional element was adjusted so that it might become a composition ratio whose Ga concentration is 15 at%, and it introduce | transduced into the heating crucible. A resistance heating device (graphite element) was used for heating the crucible. The shape of the melting crucible was 140 mmφ × 400 mmφ, the material of the mold was made of graphite, and the shape of the cast mass was continuously cast as a 65 mm w × 12 mmt plate.

After the raw materials are dissolved, the molten metal temperature is lowered to 1080 ° C, and drawing is started when the molten metal temperature and the mold temperature are stabilized. Since the dummy bar is inserted in the front end of the mold, the solidified casting piece is taken out by pulling out the dummy bar.

The drawing pattern was performed by repetition of 0.5 second drive and 2.5 second stop, frequency was changed, and the drawing speed was 90 mm / min. The drawing speed (mm / min) and the cooling rate (° C / min) are proportional to each other. When the drawing speed (mm / min) is increased, the cooling rate also increases. As a result, it became the cooling rate of 650 degreeC / min.

The obtained casting piece had a structure in which Ga was dissolved in Ga (α phase), and the oxygen concentration was less than 10 wtppm. Fine dendrite structures were formed in the cast tissue, which consisted of primary and secondary dendrite arms. The secondary dendrite arm spacing was 28 mu m, the length of the secondary dendrite was 33 mu m, and the width was 19 mu m.

Between secondary dendrite arms, a phase with high Ga concentration (segregation phase, abnormality) was observed. Since this is a structure sandwiched between secondary dendrite arms, since the dendrites are formed finely, this segregation phase (above) was also uniformly dispersed.

The results are shown in Table 1. Next, the photomicrograph of the surface which machined this casting piece into target shape, grind | polishing further, and the grinding | polishing surface etched with the hydrochloric acid solution containing ferric chloride is shown in FIG. Moreover, the surface analysis result of FE-EPMA is shown in the upper figure of FIG. As shown in this figure, the cast structure in which the Ga phase (segregation phase) was uniformly dispersed was obtained.

Thus, sputtering using the Cu-Ga alloy target which has a small amount of oxygen and the cast structure which Ga phase (segregation phase) disperse | distributed uniformly was produced, and the particle | grains generate | occur | produced little and the homogeneous Cu-Ga type alloy film was obtained.

(Example 3)

First, 20 kg of copper (Cu: purity 4N) raw materials were put into a carbon crucible, the inside of the crucible was made into nitrogen gas atmosphere, and it heated to 1250 degreeC. This high temperature heating is for welding a dummy bar and molten Cu-Ga alloy.

Next, Ga (purity: 4N) which is an additional element was adjusted so that it might become a composition ratio whose Ga concentration is 20 at%, and it introduce | transduced into the heating crucible. A resistance heating device (graphite element) was used for heating the crucible. The shape of the melting crucible was 140 mmφ × 400 mmφ, the material of the mold was made of graphite, and the shape of the cast mass was continuously cast as a 65 mm w × 12 mmt plate.

After the raw materials are dissolved, the molten metal temperature is lowered to 1080 ° C, and drawing is started when the molten metal temperature and the mold temperature are stabilized. Since the dummy bar is inserted in the front end of the mold, the solidified casting piece is taken out by pulling out the dummy bar.

The drawing pattern was repeated with 0.5 second drive and 2.5 second stop, the frequency was changed, and the drawing speed was 50 mm / min. The drawing speed (mm / min) and the cooling rate (° C / min) are proportional to each other. When the drawing speed (mm / min) is increased, the cooling rate also increases. As a result, it became the cooling rate of 350 degreeC / min.

The obtained cast piece had a structure in which Ga was dissolved in Ga (α phase), the oxygen concentration was less than 10 wtppm, and fine dendrite structures were formed. The secondary dendrite arm spacing was 48 µm, the length of the secondary dendrites was 45 µm, and the width was 25 µm.

Between secondary dendrite arms, a phase with high Ga concentration (segregation phase, abnormality) was observed. Since this is a structure sandwiched between secondary dendrite arms, since the dendrites are formed finely, this segregation phase (above) was also uniformly dispersed.

The results are shown in Table 1. Next, the photomicrograph of the surface which machined this casting piece into target shape, grind | polishing further, and the grinding | polishing surface etched with the hydrochloric acid solution containing ferric chloride is shown in FIG. As a result, a cast structure in which the Ga phase (segregation phase) was uniformly dispersed could be obtained. Thus, sputtering using the Cu-Ga alloy target which has a small amount of oxygen and the cast structure which Ga phase (segregation phase) disperse | distributed uniformly was produced, and the particle | grains generate | occur | produced little and the homogeneous Cu-Ga type alloy film was obtained.

(Example 4)

First, 20 kg of copper (Cu: purity 4N) raw materials were put into a carbon crucible, the inside of the crucible was made into nitrogen gas atmosphere, and it heated to 1250 degreeC. This high temperature heating is for welding a dummy bar and molten Cu-Ga alloy.

Next, Ga (purity: 4N) which is an additional element was adjusted so that it might become a composition ratio whose Ga concentration is 20 at%, and it introduce | transduced into the heating crucible. A resistance heating device (graphite element) was used for heating the crucible. The shape of the melting crucible was 140 mmφ × 400 mmφ, the material of the mold was made of graphite, and the shape of the cast mass was continuously cast as a 65 mm w × 12 mmt plate.

After the raw materials are dissolved, the molten metal temperature is lowered to 1080 ° C, and drawing is started when the molten metal temperature and the mold temperature are stabilized. Since the dummy bar is inserted in the front end of the mold, the solidified casting piece is taken out by pulling out the dummy bar.

The drawing pattern was performed by repetition of 0.5 second drive and 2.5 second stop, frequency was changed, and the drawing speed was 90 mm / min. The drawing speed (mm / min) and the cooling rate (° C / min) are proportional to each other. When the drawing speed (mm / min) is increased, the cooling rate also increases. As a result, it became the cooling rate of 650 degreeC / min.

The obtained cast piece had a structure in which Ga was dissolved in Ga (α phase), the oxygen concentration was less than 10 wtppm, and fine dendrite structures were formed. The secondary dendrite arm spacing was 32 탆, the length of the secondary dendrites was 35 탆, and the width was 21 탆.

Between secondary dendrite arms, a phase with high Ga concentration (segregation phase, abnormality) was observed. Since this is a structure sandwiched between secondary dendrite arms, since the dendrites are formed finely, this segregation phase (above) was also uniformly dispersed.

The results are shown in Table 1. Next, the photomicrograph of the surface which machined this casting piece into target shape, grind | polishing further, and the grinding | polishing surface etched with the hydrochloric acid solution containing ferric chloride is shown in FIG. Moreover, the surface analysis result of FE-EPMA is shown in the upper figure of FIG. As shown in this figure, the cast structure in which the Ga phase (segregation phase) was uniformly dispersed was obtained.

Thus, sputtering using the Cu-Ga alloy target which has a small amount of oxygen and the cast structure which Ga phase (segregation phase) disperse | distributed uniformly was produced, and the particle | grains generate | occur | produced little and the homogeneous Cu-Ga type alloy film was obtained.

(Comparative Example 1)

First, 20 kg of copper (Cu: purity 4N) raw materials were put into a carbon crucible, the inside of the crucible was made into nitrogen gas atmosphere, and it heated to 1250 degreeC. This high temperature heating is for welding a dummy bar and molten Cu-Ga alloy.

Next, Ga (purity: 4N) which is an additional element was adjusted so that it might become a composition ratio whose Ga concentration is 15 at%, and it introduce | transduced into the heating crucible. A resistance heating device (graphite element) was used for heating the crucible. The shape of the melting crucible was 140 mmφ × 400 mmφ, the material of the mold was made of graphite, and the shape of the cast mass was continuously cast as a 65 mm w × 12 mmt plate.

After the raw materials are dissolved, the molten metal temperature is lowered to 1080 ° C, and drawing is started when the molten metal temperature and the mold temperature are stabilized. Since the dummy bar is inserted in the front end of the mold, the solidified casting piece is taken out by pulling out the dummy bar.

The drawing pattern was repeated with 0.5 second drive and 2.5 second stop, the frequency was changed, and the drawing speed was 30 mm / min. The drawing speed (mm / min) and the cooling rate (° C / min) are proportional to each other. When the drawing speed (mm / min) is increased, the cooling rate also increases. As a result, it became the cooling rate of 200 degreeC / min.

The obtained cast piece had a structure in which Ga was dissolved (Ga phase) in Cu, the oxygen concentration was less than 10 wtppm, and coarse dendrite structures were formed. The secondary dendrite arm spacing was 94 µm, the length of the secondary dendrites was 64 µm, and the width was 61 µm. The phase (segregation phase, abnormality) with high Ga concentration was observed between secondary dendrite arms, but since the dendrites were large, the segregation phase (ideality) was also large.

The results are shown in Table 1. Next, the photomicrograph of the surface which machined this casting piece into target shape, grind | polishing further, and the grinding | polishing surface etched with the hydrochloric acid solution containing ferric chloride is shown in FIG. As described above, although the amount of oxygen is small, the Ga phase (segregation phase) became a Cu-Ga alloy target having a coarse cast structure. By sputtering using this target, generation | occurrence | production of a particle increased and the homogeneous Cu-Ga type alloy film was not obtained.

(Comparative Example 2)

First, 20 kg of copper (Cu: purity 4N) raw materials were put into a carbon crucible, the inside of the crucible was made into nitrogen gas atmosphere, and it heated to 1250 degreeC. This high temperature heating is for welding a dummy bar and molten Cu-Ga alloy.

Next, Ga (purity: 4N) which is an additional element was adjusted so that it might become a composition ratio whose Ga concentration is 20 at%, and it introduce | transduced into the heating crucible. A resistance heating device (graphite element) was used for heating the crucible. The shape of the melting crucible was 140 mmφ × 400 mmφ, the material of the mold was made of graphite, and the shape of the cast mass was continuously cast as a 65 mm w × 12 mmt plate.

After the raw materials are dissolved, the molten metal temperature is lowered to 1080 ° C, and drawing is started when the molten metal temperature and the mold temperature are stabilized. Since the dummy bar is inserted in the front end of the mold, the solidified casting piece is taken out by pulling out the dummy bar.

The drawing pattern was repeated with 0.5 second drive and 2.5 second stop, the frequency was changed, and the drawing speed was 30 mm / min. The drawing speed (mm / min) and the cooling rate (° C / min) are proportional to each other. When the drawing speed (mm / min) is increased, the cooling rate also increases. As a result, it became the cooling rate of 200 degreeC / min.

The obtained cast piece had a structure in which Ga was dissolved (Ga) in Cu, the oxygen concentration was less than 10 wtppm, and coarse dendrites were formed. The secondary dendrite arm spacing was 98 µm, the length of the secondary dendrites was 62 µm, and the width was 65 µm.

The phase (segregation phase, abnormality) with high Ga concentration was observed between secondary dendrite arms, but since the dendrites were large, the segregation phase (ideality) was also large.

The results are shown in Table 1. Next, the photomicrograph of the surface which machined this casting piece into target shape, grind | polishing further, and the grinding | polishing surface etched with the hydrochloric acid solution containing ferric chloride is shown in FIG. As described above, although the amount of oxygen is small, the Ga phase (segregation phase) became a Cu-Ga alloy target having a coarse cast structure. By sputtering using this target, generation | occurrence | production of a particle increased and the homogeneous Cu-Ga type alloy film was not obtained.

According to the present invention, there is a great advantage that the gas component such as oxygen can be reduced in comparison with the sintered compact target, and the oxygen is reduced by solidifying the sputtering target having this cast structure continuously under the solidification conditions at a constant cooling rate, Moreover, it has the effect that the target of the quality casting structure which formed many fine dendrites can be obtained.

By sputtering using a Cu-Ga alloy target having a casting structure in which a small amount of fine resinous crystals are dispersed in such a small amount of oxygen, it is possible to obtain a homogeneous Cu-Ga-based alloy film with little generation of particles. It has the effect that a manufacturing cost of -Ga alloy target can be greatly reduced.

Since the light absorption layer and the CIGS solar cell can be manufactured from such a sputter film, the fall of the conversion efficiency of a CIGS solar cell is suppressed and it has the outstanding effect that a low cost CIGS solar cell can be manufactured. Since a light absorption layer and a CIGS solar cell can be manufactured from such a sputter film, it is useful for the solar cell for suppressing the fall of the conversion efficiency of a CIGS solar cell.

Claims (14)

Ga is 15 at% or more and 22 at% or less, and the remainder is a plate-shaped Cu-Ga alloy sputtering target composed of Cu and unavoidable impurities. The dendrite structure is dispersed in the structure which consists of the alpha phase or the mixed phase of the alpha phase and the ζ phase, The dendrite structure (resin phase top) is 2 which grew laterally from the primary arm and the primary arm. Cu- which consists of a primary arm, the average length of a secondary arm is 30-60 micrometers, the average width of a secondary arm is 10-30 micrometers, and the average space | interval between the secondary arms is 20-80 micrometers. Ga alloy sputtering target. The method of claim 1,
The maximum diameter of a primary arm is 5-30 micrometers, Cu-Ga alloy sputtering target characterized by the above-mentioned. The method of claim 1,
A Cu-Ga alloy sputtering target, having a Ga concentration that is thicker than a dendrite structure between secondary arms of the dendrite structure. 3. The method of claim 2,
A Cu-Ga alloy sputtering target, having a Ga concentration that is thicker than a dendrite structure between secondary arms of the dendrite structure. The method of claim 3, wherein
A Ga-Ga alloy sputtering target, wherein a Ga concentration is higher than a dendrite structure is an α phase or a ζ phase. 5. The method of claim 4,
A Ga-Ga alloy sputtering target, wherein a Ga concentration is higher than a dendrite structure is an α phase or a ζ phase. 7. The method according to any one of claims 1 to 6,
An Cu-Ga alloy sputtering target, wherein the oxygen content is 20 wtppm or less. The target raw material is dissolved in a graphite crucible, and the molten metal is poured into a mold having a water-cooled probe to continuously manufacture a plate-shaped casting made of a Cu-Ga alloy, which is further machined to form a plate-shaped Cu-Ga. A method for producing an alloy target, the method of producing a Cu-Ga alloy sputtering target, characterized by controlling the solidification rate from the melting point of the cast body to 300 ° C at 300 to 1000 ° C / min. The target raw material is dissolved in a graphite crucible, and the molten metal is poured into a mold having a water-cooled probe to continuously manufacture a plate-shaped casting made of a Cu-Ga alloy, which is further machined to form a plate-shaped Cu-Ga. A method for producing an alloy target, wherein the target according to any one of claims 1 to 6 is produced by controlling the solidification rate from the melting point of the cast body to 300 ° C at 300 to 1000 ° C / min. The manufacturing method of the Cu-Ga alloy sputtering target characterized by the above-mentioned. The target raw material is dissolved in a graphite crucible, and the molten metal is poured into a mold having a water-cooled probe to continuously manufacture a plate-shaped casting made of a Cu-Ga alloy, which is further machined to form a plate-shaped Cu-Ga. A method for producing an alloy target, wherein the target according to claim 7 is produced by controlling the solidification rate from the melting point of the cast body to 300 ° C. at 300 to 1000 ° C./min. Method for producing an alloy sputtering target. The method of claim 8,
A manufacturing method of the Cu-Ga alloy sputtering target characterized by drawing with a drawing speed of 50 mm / min-150 mm / min. The method of claim 8,
It manufactures using a horizontal continuous casting method, The manufacturing method of the Cu-Ga alloy sputtering target characterized by the above-mentioned. The method of claim 8,
By controlling the solidification rate from the melting point of the cast to 300 ℃ to 300 ~ 1000 ℃ / min, it is characterized by adjusting the amount and concentration of the α phase or the mixed phase of the α phase and ζ phase formed during casting Method for producing a Cu-Ga alloy sputtering target. The method of claim 11,
By controlling the solidification rate from the melting point of the cast to 300 ℃ to 300 ~ 1000 ℃ / min, it is characterized by adjusting the amount and concentration of the α phase or the mixed phase of the α phase and ζ phase formed during casting Method for producing a Cu-Ga alloy sputtering target.

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