WO2016047556A1 - Sputtering target and method for manufacturing same - Google Patents

Sputtering target and method for manufacturing same Download PDF

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WO2016047556A1
WO2016047556A1 PCT/JP2015/076515 JP2015076515W WO2016047556A1 WO 2016047556 A1 WO2016047556 A1 WO 2016047556A1 JP 2015076515 W JP2015076515 W JP 2015076515W WO 2016047556 A1 WO2016047556 A1 WO 2016047556A1
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Prior art keywords
phase
sputtering target
alloy
raw material
material powder
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PCT/JP2015/076515
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French (fr)
Japanese (ja)
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啓太 梅本
張 守斌
恒太郎 浦山
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三菱マテリアル株式会社
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Priority claimed from JP2015181053A external-priority patent/JP6634750B2/en
Application filed by 三菱マテリアル株式会社 filed Critical 三菱マテリアル株式会社
Priority to EP15845101.3A priority Critical patent/EP3199662A4/en
Priority to CN201580033520.5A priority patent/CN106471150B/en
Priority to US15/511,753 priority patent/US20170298499A1/en
Publication of WO2016047556A1 publication Critical patent/WO2016047556A1/en

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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22FWORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/12Metallic powder containing non-metallic particles
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C28/00Alloys based on a metal not provided for in groups C22C5/00 - C22C27/00
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C32/00Non-ferrous alloys containing at least 5% by weight but less than 50% by weight of oxides, carbides, borides, nitrides, silicides or other metal compounds, e.g. oxynitrides, sulfides, whether added as such or formed in situ
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C9/00Alloys based on copper
    • CCHEMISTRY; METALLURGY
    • C23COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23CCOATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/34Sputtering

Definitions

  • the present invention relates to a sputtering target used for forming a Cu—In—Ga—Se compound film (hereinafter sometimes abbreviated as CIGS film) for forming a light absorption layer of a CIGS thin film solar cell, and It relates to the manufacturing method.
  • CIGS film Cu—In—Ga—Se compound film
  • This application claims priority based on Japanese Patent Application No. 2014-192151 filed in Japan on September 22, 2014, and Japanese Patent Application No. 2015-181053 filed on September 14, 2015 in Japan. , The contents of which are incorporated herein.
  • a Mo electrode layer serving as a positive electrode is formed on a soda lime glass substrate, and a light absorption layer composed of a CIGS film is formed on the Mo electrode layer. It has a basic structure in which a buffer layer made of ZnS, CdS, or the like is formed on the light absorption layer, and a transparent electrode layer to be a negative electrode is formed on the buffer layer.
  • a sputtering method suitable for film formation on a large-area substrate has been proposed.
  • an In film is formed by sputtering using an In sputtering target.
  • a Cu—Ga binary alloy film is sputtered on the In film using a Cu—Ga binary alloy sputtering target, and then, the In film and the Cu—Ga binary alloy film thus obtained are formed.
  • a selenization method is employed as a method of forming a CIGS film by heat-treating the laminated precursor film in an Se atmosphere.
  • the order of forming the In film and the Cu—Ga binary alloy film may be reversed.
  • a Cu—Ga alloy is formed by sputtering to a thickness of about 500 nm, and a laminated film is formed on the film by sputtering an In film to a thickness of about 500 nm. Is heated in H 2 Se gas at 500 ° C., and Se is diffused into CuGaIn to form a Cu—In—Ga—Se compound film.
  • the Cu—Ga alloy sputtering target is indispensable for manufacturing a CIGS solar cell using a Cu—In—Ga—Se compound film (CIGS film) as a light absorption layer. It is.
  • the band gap changes depending on the ratio of In and Ga, and the light absorption wavelength varies. For example, when the Ga ratio increases, the light absorption wavelength shifts to the lower wavelength side. It is known. Therefore, a thin film solar cell using a Cu—Ga—Se 2 compound film not containing In is expected to be applied as a top cell in a tandem structure of a CIGS thin film solar cell. Therefore, a Cu—Ga alloy sputtering target containing a high concentration of Ga is required to form a Cu—Ga—Se 2 compound film.
  • Patent Documents 2 and 3 Various types of Cu—Ga alloy sputtering targets containing high concentrations of Ga have been proposed (see, for example, Patent Documents 2 and 3).
  • Patent Document 2 describes a Cu—Ga alloy containing a plurality of phases, containing 40 wt% or more and 60 wt% or less of Ga, with the balance being made of Cu and inevitable impurities.
  • a Cu—Ga alloy sputtering target containing a segregation phase containing 80% by weight or more is disclosed.
  • Patent Document 3 is composed of a Cu—Ga alloy material having an average composition of Ga of 32 wt% or more and 45 wt% or less, and the balance of Cu, unavoidable impurities, and unavoidable voids, and 65 wt%.
  • a Cu—Ga alloy sputtering target is disclosed in which a Cu—Ga alloy phase containing at least% gallium includes at least one of a ⁇ 1 phase, a ⁇ 2 phase, and
  • Japanese Laid-Open Patent Publication No. 10-135495 A) Japanese Unexamined Patent Publication No. 2010-280944 (A) Japanese Patent Application Laid-Open No. 2011-241452 (A)
  • the Cu—Ga alloy in the Cu—Ga alloy sputtering target disclosed in Patent Document 2 is manufactured by melting the raw material and then rapidly solidifying the molten raw material. Specifically, a melting step of heating and melting a mixture containing 40 wt% or more and 60 wt% or less of Ga and the balance of Cu and inevitable impurities in a melting furnace, cooling the molten mixture to 254 ° C. , A cooling step in which the ⁇ 3 phase of the Cu—Ga alloy is solidified in the melted mixture, followed by a temperature of 254 ° C. in the cooling step and then 200 ° C.
  • the Cu—Ga alloy sputtering target according to Patent Document 2 contains a segregation phase containing Ga: 80% by weight or more, although Ga is contained at a high concentration but relatively poor in workability.
  • a sputtering target obtained by adding an alkali metal such as Na to a Cu—Ga alloy has the same problem as described above.
  • the entire Cu—Ga alloy material having a volume in a region containing less than 47% by weight of copper is used.
  • a Cu—Ga alloy material having a volume ratio of 2% or less is proposed.
  • the portion excluding the region containing less than 47% by weight of copper becomes a region containing 32% by weight to 53% by weight or less of gallium. That is, when the gallium ratio is 32% by weight or more, the brittle ⁇ phase becomes the main phase, and thus there is a problem that cracks and chips are likely to occur during processing during the production of the sputtering target.
  • the present invention has been made in view of the above-described problems, and an object thereof is to provide a Cu—Ga alloy sputtering target that is difficult to break during processing even if it contains a high concentration of Ga, and a method for manufacturing the same. .
  • a sputtering target of one embodiment of the present invention contains 30.0 to 67.0 atomic% of Ga, with the balance being Cu and inevitable impurities.
  • the sputtering target of (1) is characterized in that the average crystal grain size of the ⁇ phase is 5.0 to 50.0 ⁇ m.
  • the sputtering target of (1) is characterized in that the average crystal grain size of the ⁇ phase is 5.0 to 100.0 ⁇ m.
  • the ⁇ phase relative to the main peak intensity of the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern of the sputtering surface The ratio of the main peak intensity of the assigned diffraction peak is 0.01 to 10.0.
  • the Na in the sputtering target of (5) is characterized by being contained in a state of at least one Na compound among sodium fluoride, sodium sulfide, and sodium selenide.
  • Another aspect of the present invention is a method for manufacturing a sputtering target according to any one of the above (1) to (4) (hereinafter referred to as “the manufacturing method of the sputtering target of the present invention”).
  • XRD X-ray diffraction
  • the firing temperature is 254 ° C. or higher and 450 ° C. or lower, preferably 254 ° C. or higher and lower than 400 ° C., and the main peak intensity ratio is higher than 0.5.
  • the firing temperature is 254 ° C. or higher and 450 ° C. or lower, preferably 254 ° C. or higher and lower than 400 ° C., and the main peak intensity ratio is higher than 0.5.
  • the mixing ratio of the raw material powder is 35% or less, preferably 30% or less, and contains 30.0 to 42.6 atomic% of Ga, with the balance being a component composition consisting of Cu and inevitable impurities.
  • the mixed powder is sintered in a non-oxidizing atmosphere or a reducing atmosphere at a temperature of 150 to 400 ° C. to produce a sintered body.
  • the present invention has the following effects. That is, according to the sputtering target of the present invention, the sintered body containing 30.0 to 67.0 atomic% of Ga and the balance of Cu and inevitable impurities is used as the sintered body of the Cu—Ga alloy. Since the phase matrix has a structure in which the ⁇ phase of the Cu—Ga alloy is dispersed, in the sintered body of the Cu—Ga alloy, it is possible to suppress the enlargement of the ⁇ phase crystal grains, and at the time of target processing The generation of cracks can be reduced.
  • a raw material powder containing 6 atomic% Ga and mixed so that the balance is composed of Cu and inevitable impurities is sintered at a temperature of 150 to 400 ° C.
  • the ⁇ phase matrix of the Cu—Ga alloy has a structure in which the ⁇ phase of the Cu—Ga alloy is dispersed, and particularly preferably, the average particle diameter of the ⁇ phase is 5.0 to 50.
  • the ratio of the main peak intensity of the diffraction peak attributed to the ⁇ phase to the main peak intensity of the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern ( ⁇ phase intensity / A sintered body having a ⁇ phase strength of 0.01 to 10.0 can be obtained.
  • the Cu—Ga alloy sputtering target containing high-concentration Ga which is one embodiment of the present invention, is difficult to break during processing, and the yield of target production can be improved.
  • a light absorption layer of a CIGS thin film solar cell containing a high concentration of Ga can be formed, which can contribute to improvement of photoelectric conversion efficiency in the light absorption layer, and manufacture a solar cell with high power generation efficiency. It becomes possible.
  • the sputtering target of the embodiment contains 30.0 to 67.0 atomic% of Ga, and the remainder has a component composition consisting of Cu and inevitable impurities.
  • Cu In the ⁇ phase matrix of the Cu—Ga alloy, Cu It is characterized by comprising a sintered body having a structure in which the ⁇ phase of a -Ga alloy is dispersed.
  • the structure in which the ⁇ phase is dispersed in the ⁇ phase matrix means that in the sintered body, the ⁇ phase and the ⁇ phase precipitated during sintering coexist, and among the ⁇ phase and the ⁇ phase, It refers to a state in which one phase surrounds the other phase and each phase is dispersed without being assembled into a macro.
  • the basis for setting the Ga content in the range of 30.0 to 67.0 atomic% is that when the Ga content is less than 30.0 atomic%, the ⁇ phase is almost eliminated, and the structure Is substantially a single phase of ⁇ phase, and the target processability is abruptly deteriorated.
  • the content exceeds 67.0 atomic%, the ⁇ phase exists, but pure Ga is present. This is because (melting point is 29.6 ° C.) is generated, Ga is melted by heat during target cutting, and target cracks are generated starting from the melted Ga.
  • the ⁇ phase in the present embodiment includes ⁇ and ⁇ 1 to ⁇ 3 in the state diagram shown in FIG.
  • FIG. 2 is an X-ray diffraction (XRD) pattern obtained by analyzing the above-described sputtering target by X-ray diffraction (XRD).
  • FIG. 3 is a photograph of a composition image (COMPO image) obtained by performing electron probe microanalysis (EPMA) on the above sputtering target.
  • XRD X-ray diffraction
  • the above-described sputtering target exists in a state where two phases of ⁇ phase and ⁇ phase are dispersed.
  • the whitest part shows the area
  • the dark gray area is the ⁇ phase.
  • the reason why two phases of ⁇ phase and ⁇ phase coexist in the crystal structure of the sputtering target is that the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern of the raw material Cu—Ga alloy powder. This is because the ratio between the main peak intensity of the diffraction peak and the main peak intensity of the diffraction peak attributed to the ⁇ phase is 0.01 to 10.0.
  • the firing temperature is set to 254 ° C.
  • the raw material Cu— A second Cu—Ga alloy raw material powder containing no ⁇ phase in the Ga alloy, ie, a ⁇ phase (Cu 1 ⁇ x Ga x : x 0.295 to 0.426),
  • the raw material powder is composed of the ⁇ phase from the Cu—Ga alloy raw material powder composed of the ⁇ phase.
  • the mixing ratio of the Cu—Ga alloy raw material powder with the ⁇ phase ratio exceeding 0.5 is preferably 30% or less.
  • the mixing ratio exceeds 30%, the amount of liquid phase from the ⁇ phase is large even if Ga diffuses from the Cu—Ga alloy raw material powder consisting of the ⁇ phase to the Cu—Ga alloy raw material powder consisting of the ⁇ phase. Therefore, it is difficult to maintain the shape of the sintered body.
  • the advantage of the coexistence of two phases, ⁇ phase and ⁇ phase is that the presence of the ⁇ phase suppresses the enlargement of the crystal grains of the ⁇ phase, reduces the average crystal grain size in the target structure, and allows the sputtering target to be processed. It is difficult to break.
  • XRD X-ray diffraction
  • the main phase of the matrix is formed of a single phase of ⁇ phase, and there is no ⁇ phase containing a relatively large amount of Ga. I understand that.
  • the average crystal grain size of the ⁇ phase is 5.0 to 50.0 ⁇ m
  • the average crystal grain size of the ⁇ phase is 5.0 to 100.0 ⁇ m
  • the ratio of the main peak intensity of the diffraction peak attributed to the ⁇ phase to the main peak intensity of the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern is A range of 0.01 to 10.0 is preferable.
  • the processing after the sputtering target is manufactured.
  • chipping breaking or chipping
  • the ⁇ phase ratio for representing the coexistence of two phases of the ⁇ phase and the ⁇ phase in the sputtering target is in the range of 0.01 to 10.0, the presence of the ⁇ phase causes the ⁇ phase to exist. Since the enlargement of the crystal grains is suppressed, it can be made difficult to break when the sputtering target is processed.
  • the sputtering target of this embodiment can be used when forming a CIGS film that becomes a light absorption layer of a solar cell
  • Na is added to the sputtering target in an amount of 0.05 to 0.05 in order to increase its photoelectric conversion efficiency.
  • the Na may be contained in an amount of 15 atomic%, and the Na may be contained in the form of at least one Na compound among sodium fluoride, sodium sulfide, and sodium selenide.
  • 0.05 to 15 atomic% of K is contained instead of Na, and the K is contained in potassium fluoride, potassium chloride, potassium bromide, potassium iodide, potassium sulfide, potassium selenide, niobium. It can also be made to contain in the state of at least 1 sort (s) of K compound among potassium acid. Na and K may be added simultaneously. In this case, the total of Na and K is 0.05 to 15 atomic%.
  • the method for producing a sputtering target according to this embodiment is a method for producing the sputtering target according to the above embodiment, which contains 40.0 to 67.0 atomic% of Ga, with the balance being Cu and inevitable impurities.
  • -Ga alloy powder the ratio of the main peak intensity of the diffraction peak attributed to the ⁇ phase to the main peak intensity of the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern ( ⁇ phase intensity / ⁇ If the ratio of the main peak intensities is 0.5 or less in a non-oxidizing atmosphere or a reducing atmosphere, the firing temperature is 254 ° C.
  • the method has a step of sintering at a firing temperature of less than 254 ° C. to produce a sintered body. That is, in this sputtering target manufacturing method, the crystal grain size in the sintered body can be easily adjusted by using Cu—Ga alloy powder.
  • the ratio of the main peak intensity of the diffraction peak attributed to the ⁇ phase to the main peak intensity of the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern ( ⁇ phase intensity / ⁇ phase intensity) is 0
  • the sintering temperature for obtaining the sintered body related to the sputtering target was set in the range of 150 to 450 ° C., so that the ⁇ phase of the Cu—Ga alloy was used in the sintered body.
  • a structure in which the ⁇ phase of the Cu—Ga alloy is dispersed in the matrix can be formed, and the average crystal grain size of the ⁇ phase can be made 50.0 ⁇ m or less.
  • Cu—Ga is included in the ⁇ phase matrix of the Cu—Ga alloy.
  • the ⁇ phase of the alloy can be made more dispersed, and the average crystal grain size of the ⁇ phase can be made 50.0 ⁇ m or less.
  • the manufacturing procedure of the Cu—Ga binary sputtering target of the present embodiment is, for example, as an alloy powder, Cu metal lump, Ga metal lump, and these are weighed to a predetermined amount, and each is melted in a crucible,
  • the Cu—Ga alloy atomized powder as the raw material powder is filled with a Cu metal lump and a Ga metal lump in a carbon crucible at a predetermined composition ratio, and a gas atomizing method using Ar gas. It is prepared with.
  • any one of hot press, hot isostatic pressing and atmospheric sintering is used, and the holding temperature at the time of sintering is set within a range of 150 to 450 ° C. did.
  • the non-oxidizing atmosphere refers to an atmosphere containing no oxygen such as an Ar atmosphere or a vacuum atmosphere.
  • the reducing atmosphere refers to an atmosphere containing a reducing gas such as H 2 or CO.
  • the surface portion and the outer peripheral portion of the obtained sintered body are turned to produce a sputtering target having a diameter of 50 mm and a thickness of 6 mm.
  • the processed sputtering target is bonded to a backing plate made of Cu or sus (stainless steel) or other metal (for example, Mo) using In as a solder, and is used for sputtering.
  • a vacuum pack or a pack obtained by replacing the entire target with a vacuum in order to prevent oxidation and moisture absorption.
  • the thus produced sputtering target is subjected to a DC magnetron sputtering apparatus using Ar gas as a sputtering gas.
  • direct current (DC) sputtering may be performed using a pulsed DC power source to which a pulse voltage is applied or a DC power source without a pulse.
  • the ⁇ phase is dispersed in the ⁇ phase matrix in the sintered body of the Cu—Ga alloy by the above manufacturing procedure.
  • the firing temperature is set to 254 ° C. or more, so that Cu— Since a liquid phase of the ⁇ phase appears from the Ga alloy powder and so-called liquid phase sintering is performed, densification easily occurs, and a high-density sintered body can be obtained while performing powder sintering by low-temperature hot pressing. In the process of cooling the sintered body, ⁇ phase precipitation occurs at around 254 ° C.
  • the liquid phase from the ⁇ phase can be set by setting the firing temperature to less than 254 ° C. Therefore, the ⁇ phase in the raw material Cu—Ga alloy is retained. At this time, if the firing temperature is set to 254 ° C. or higher, the amount of liquid phase from the ⁇ phase is too large, and it is difficult to maintain the shape of the sintered body. According to the Cu—Ga phase diagram described in “Binary Alloy Phase Diagrams (2nd edition)” described above, this phase separation is expected to occur whenever the atomic ratio of Ga is 42.6% or more. .
  • a structure in which the ⁇ phase of the Cu—Ga alloy is dispersed in the ⁇ phase matrix of the Cu—Ga alloy and can do.
  • the advantage of the two-phase coexistence is that the presence of the ⁇ phase suppresses the enlargement of the crystal grains of the ⁇ phase, reduces the average grain size of the target structure, and makes it difficult to break during sputtering target processing.
  • a 4N (purity 99.99%) Cu metal block and a 4N (purity 99.99%) Ga metal block were prepared.
  • Raw material powder A with a Ga content adjusted by a gas atomization method using Ar gas after weighing each component composition as shown in Table 1 to a total weight of 1200 g, filling each in a carbon crucible and dissolving it And raw material powder B was produced, and these raw material powders were classified by passing through a 125 ⁇ m sieve.
  • gas atomization conditions the melting temperature was 1000 to 1200 ° C.
  • the injection gas pressure was 28 kgf / cm 2
  • the nozzle diameter was 1.5 mm.
  • a CuGa raw material powder was prepared using a raw material powder A having a structure dispersed in a ⁇ phase matrix at a ⁇ phase ratio (mixing ratio 100%).
  • the mixing conditions using the rocking mixer were a rotational speed of 72 rpm and a mixing time of 30 minutes.
  • the raw material powder A and the Na additive shown in Table 2 were weighed at the mixing ratio of the raw material powder A shown in Table 1 and the Na additive shown in Table 2, and then rocked with a rocking mixer.
  • the raw material powder was obtained by mixing. Moreover, in Examples 8 and 11, Na additive shown in Table 2 was added to the mixture obtained by weighing the raw material powder A and the raw material powder B at the mixing ratio shown in Table 1 and mixing them with a rocking mixer. Were added at a mixing ratio shown in Table 2 and then mixed with a rocking mixer to obtain a CuGa raw material powder. As the Na additive, 3N (purity 99.9%) Na compound powder was used. In Examples 14 and 19 to 23, the raw material powder A and the K additive shown in Table 2 were weighed at the mixing ratio of the raw material powder A shown in Table 1 and the mixing ratio of the K additive shown in Table 2. And mixed with a rocking mixer to obtain a raw material powder.
  • Example 17 the raw material powder A, the raw material powder B, and the K additive shown in Table 2 were mixed, the mixing ratio of the raw material powder A and the raw material powder B shown in Table 1 and the mixing of the K additive shown in Table 2 After weighing in proportion, mixing was performed with a rocking mixer to obtain a raw material powder.
  • Example 18 the raw material powder A, the Na additive and the K additive shown in Table 2, the mixing ratio of the raw material powder A shown in Table 1, and the Na additive and K additive shown in Table 2 were mixed. Weighed at a ratio and mixed with a rocking mixer to obtain a raw material powder.
  • I obs ( ⁇ phase) is the measurement peak intensity of the ⁇ phase (102) plane
  • I obs ( ⁇ phase) is the measurement of the ⁇ phase (330) plane. Assuming the peak intensity, it is obtained by I obs ( ⁇ phase) / I obs ( ⁇ phase).
  • Example 14 shows a typical example in the case of adding a K compound instead of the Na compound.
  • a K compound instead of the Na compound.
  • the CuGa obtained previously was used.
  • a raw material powder and a K compound powder (KF) having a mixing ratio shown in Table 2 were prepared and mixed.
  • Na compound powder (NaF) and K compound powder (KCl) were similarly prepared and mixed.
  • Comparative Example 1 is a hot press at a high temperature outside the temperature range in the sputtering target manufacturing method of the present invention, in which the Ga content in the raw material powder A is smaller than that in the example and the ⁇ phase ratio is low.
  • Comparative Example 2 is a case where the content of Ga in the raw material powder A is larger than that in the Example, and there is no ⁇ phase.
  • Comparative Example 3 the raw material powder A and the raw material powder Although it is a case where B is used, it is a case where the mixing rate of the raw material powder B is high and the content of Ga in the CuGa raw material powder is smaller than in the case of the example. Moreover, although the comparative example 4 is a case where the raw material powder A and the raw material powder B are used, it is a case where the mixing ratio of the raw material powder A is high.
  • the maximum circumscribed circle is drawn for 20 crystals selected arbitrarily from the ⁇ phase (or ⁇ phase) of the image obtained by displaying the ⁇ phase (or ⁇ phase) in black, and the average of the diameters is drawn. Is the average crystal grain size in this image, and the average value of the five images is the average crystal grain size.
  • the measurement results are shown in the “ ⁇ phase average crystal grain size ( ⁇ m)” column and “ ⁇ phase average crystal grain size ( ⁇ m)” column of Table 4.
  • ⁇ Ratio of ⁇ phase For the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the main peak intensity of the diffraction peak attributed to the ⁇ phase obtained by the X-ray diffraction (XRD) pattern and the diffraction peak attributed to the ⁇ phase The ratio of the main peak intensity of the diffraction peak attributed to the ⁇ phase to the main peak intensity of the diffraction peak attributed to the ⁇ phase was calculated to determine the ratio of the ⁇ phase. The main peak intensity of the diffraction peak was the (102) plane in the ⁇ phase and the (330) plane peak intensity in the ⁇ phase.
  • This XRD pattern was measured after wet-polishing and drying the sputtering surface of the sputtering target with SiC-Paper (grit 180).
  • the apparatus and measurement conditions used for this analysis are shown below.
  • Ratio of ⁇ phase I obs ( ⁇ phase) / I obs ( ⁇ phase)
  • I obs ( ⁇ phase) is the measured intensity of the ⁇ phase (201) plane
  • I obs ( ⁇ phase) is the measured intensity of the ⁇ phase (330) plane.
  • composition images obtained by EPMA for the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the structure in which the ⁇ phase is dispersed in the ⁇ phase is indicated as “A”, One phase is shown as “B” in the “Target organization” column of Table 4.
  • the average particle diameter of the ⁇ phase is as small as 50.0 ⁇ m or less.
  • two phases of the ⁇ phase and the ⁇ phase are present. Observed, it was confirmed that the ratio of the ⁇ phase was 10.0 or less. In these examples, good results were obtained with respect to chipping during cutting, and improvement in workability was confirmed.
  • Comparative Example 1 although the raw material powder A was used as the raw material powder, the Ga component was small and hot pressing was performed at a high temperature outside the temperature range of the sputtering target manufacturing method of the present invention. No phase was generated, the target structure became a single ⁇ phase, and chipping occurred during cutting. In Comparative Example 2, Ga was too much out of the composition range of the sputtering target and the sputtering target manufacturing method of the present invention, so that Ga was eluted during processing, and the target was cracked.
  • Comparative Example 3 since the mixing ratio of the raw material powder B composed of a single phase of ⁇ phase is large, even if the raw material powder A composed of the ⁇ phase is used, the ⁇ phase is not generated, and the target structure is a single ⁇ phase. Phase and chipping occurred during cutting. In Comparative Example 4, the sputtering of the sputtering target could not be performed because the ⁇ phase melted during sintering and could not be molded. Thus, all of the comparative examples were inferior in workability.
  • the Ga content is in the range of 30.0 to 67.0 atomic% and sintered at a temperature of 150 to 400 ° C.
  • Cu -Both the diffraction peak attributed to the ⁇ phase and the diffraction peak attributed to the ⁇ phase of the Ga alloy are observed, and the ratio of the main peak intensity of the diffraction peak attributed to the ⁇ phase to the main peak intensity of the diffraction peak attributed to the ⁇ phase
  • the (ratio of the ⁇ phase) was in the range of 0.01 to 10.0.
  • the ⁇ phase containing a relatively large amount of Ga is dispersed in the matrix of ⁇ phase. It was confirmed that it had a crystal structure. Accordingly, it has been found that the occurrence of chipping (cracking, chipping) during processing can be suppressed by dispersing the ⁇ phase in the ⁇ phase matrix in the sintered body of the Cu—Ga alloy in the sputtering target of the present invention.
  • the sputtering target of the present invention has a surface roughness of 1.5 ⁇ m or less, an electric resistance of 1 ⁇ 10 ⁇ 4 ⁇ ⁇ cm or less, a metal impurity concentration of 0.1 atomic% or less, and a bending strength of 150 MPa or more. Preferably there is.
  • Each of the above-described embodiments satisfies these conditions.
  • the technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.
  • the sputtering target of the said embodiment and the said Example is a flat thing, it is good also as a cylindrical sputtering target.

Abstract

 This sputtering target comprises a sintered body having a composition containing 30.0-67.0% (atom basis) of Ga, the remainder made up by Cu and inevitable impurities; and the sintered body is provided with a structure in which a θ-phase of a Cu-Ga alloy is dispersed in a γ-phase matrix of the Cu-Ga alloy.

Description

スパッタリングターゲット及びその製造方法Sputtering target and manufacturing method thereof
 本願発明は、CIGS薄膜型太陽電池の光吸収層を形成するためのCu-In-Ga-Se化合物膜(以下、CIGS膜と略記することがある。)を形成するときに使用するスパッタリングターゲット及びその製造方法に関するものである。
 本願は、2014年9月22日に、日本に出願された特願2014-192151号、および2015年9月14日に、日本に出願された特願2015-181053号に基づき優先権を主張し、その内容をここに援用する。
The present invention relates to a sputtering target used for forming a Cu—In—Ga—Se compound film (hereinafter sometimes abbreviated as CIGS film) for forming a light absorption layer of a CIGS thin film solar cell, and It relates to the manufacturing method.
This application claims priority based on Japanese Patent Application No. 2014-192151 filed in Japan on September 22, 2014, and Japanese Patent Application No. 2015-181053 filed on September 14, 2015 in Japan. , The contents of which are incorporated herein.
 近年、光吸収層としてCIGS膜に代表されるカルコパイライト系の化合物半導体膜を用いた薄膜型太陽電池が実用に供せられるようになった。この化合物半導体膜を用いた薄膜型太陽電池は、ソーダライムガラス基板の上にプラス電極となるMo電極層を形成し、このMo電極層の上にCIGS膜からなる光吸収層が形成され、この光吸収層上にZnS、CdSなどからなるバッファ層が形成され、このバッファ層上にマイナス電極となる透明電極層が形成された基本構造を有している。 In recent years, thin film solar cells using a chalcopyrite compound semiconductor film typified by a CIGS film as a light absorption layer have come into practical use. In the thin film solar cell using this compound semiconductor film, a Mo electrode layer serving as a positive electrode is formed on a soda lime glass substrate, and a light absorption layer composed of a CIGS film is formed on the Mo electrode layer. It has a basic structure in which a buffer layer made of ZnS, CdS, or the like is formed on the light absorption layer, and a transparent electrode layer to be a negative electrode is formed on the buffer layer.
 上記光吸収層の形成方法としては、大面積の基板への成膜に適したスパッタリング法が提案されている。このスパッタリング法により上記光吸収層を形成するには、先ず、Inスパッタリングターゲットを使用してIn膜をスパッタリング成膜する。このIn膜上にCu-Ga二元系合金スパッタリングターゲットを使用してCu-Ga二元系合金膜をスパッタリング成膜し、次いで、得られたIn膜及びCu-Ga二元系合金膜からなる積層プリカーサ膜をSe雰囲気中で熱処理してCIGS膜を形成する方法としては、セレン化法が採用されている。 As a method for forming the light absorption layer, a sputtering method suitable for film formation on a large-area substrate has been proposed. In order to form the light absorption layer by this sputtering method, first, an In film is formed by sputtering using an In sputtering target. A Cu—Ga binary alloy film is sputtered on the In film using a Cu—Ga binary alloy sputtering target, and then, the In film and the Cu—Ga binary alloy film thus obtained are formed. As a method of forming a CIGS film by heat-treating the laminated precursor film in an Se atmosphere, a selenization method is employed.
 セレン化法では、In膜とCu-Ga二元系合金膜の成膜順序は逆でもよい。例えば、特許文献1に記載のセレン化法では、Cu-Ga合金を厚さ約500nmにスパッタリング成膜し、その膜上に、In膜を厚さ約500nmにスパッタリングした積層膜を形成し、これを500℃のHSeガス中で加熱し、SeをCuGaInに拡散させ、Cu-In-Ga-Se化合物膜を形成している。
 このセレン化法による場合には、Cu-Ga合金スパッタリングターゲットは、Cu-In-Ga-Se化合物膜(CIGS膜)を光吸収層に用いたCIGS系太陽電池を製造するために、必須なものである。
In the selenization method, the order of forming the In film and the Cu—Ga binary alloy film may be reversed. For example, in the selenization method described in Patent Document 1, a Cu—Ga alloy is formed by sputtering to a thickness of about 500 nm, and a laminated film is formed on the film by sputtering an In film to a thickness of about 500 nm. Is heated in H 2 Se gas at 500 ° C., and Se is diffused into CuGaIn to form a Cu—In—Ga—Se compound film.
In the case of this selenization method, the Cu—Ga alloy sputtering target is indispensable for manufacturing a CIGS solar cell using a Cu—In—Ga—Se compound film (CIGS film) as a light absorption layer. It is.
 ところで、カルコパイライト系のCIGS膜は、InとGaの比によってバンドギャップが変化して、光の吸収波長が変動すること、例えば、Ga比が高くなると、光の吸収波長が低波長側ヘシフトすることが知られている。そこで、Inを含まないCu-Ga-Se化合物膜による薄膜型太陽電池は、CIGS系薄膜型太陽電池のタンデム構造におけるトップセルとしての応用が期待されている。そのため、Cu-Ga-Se化合物膜を成膜するため、高濃度のGaを含有したCu-Ga合金スパッタリングターゲットが要求される。 By the way, in the chalcopyrite CIGS film, the band gap changes depending on the ratio of In and Ga, and the light absorption wavelength varies. For example, when the Ga ratio increases, the light absorption wavelength shifts to the lower wavelength side. It is known. Therefore, a thin film solar cell using a Cu—Ga—Se 2 compound film not containing In is expected to be applied as a top cell in a tandem structure of a CIGS thin film solar cell. Therefore, a Cu—Ga alloy sputtering target containing a high concentration of Ga is required to form a Cu—Ga—Se 2 compound film.
 この高濃度のGaを含有したCu-Ga合金スパッタリングターゲットは、種々提案されている(例えば、特許文献2、3を参照)。特許文献2には、複数の相を含むCu-Ga合金であって、40重量%以上60重量%以下のGaを含み、残部がCu及び不可避的不純物からなり、その複数相には、Gaを80重量%以上含む偏析相を含んだCu-Ga合金スパッタリングターゲットが開示されている。また、特許文献3には、平均組成が32重量%以上45重量%以下のGaと、残部がCu、不可避的不純物、及び不可避的な空隙とからなるCu-Ga合金材で構成され、65重量%以上のガリウムを含むCu-Ga合金相が、γ1相、γ2相、及びγ3相のうちの少なくとも一つの相を含んだCu-Ga合金スパッタリングターゲットが開示されている。 Various types of Cu—Ga alloy sputtering targets containing high concentrations of Ga have been proposed (see, for example, Patent Documents 2 and 3). Patent Document 2 describes a Cu—Ga alloy containing a plurality of phases, containing 40 wt% or more and 60 wt% or less of Ga, with the balance being made of Cu and inevitable impurities. A Cu—Ga alloy sputtering target containing a segregation phase containing 80% by weight or more is disclosed. Further, Patent Document 3 is composed of a Cu—Ga alloy material having an average composition of Ga of 32 wt% or more and 45 wt% or less, and the balance of Cu, unavoidable impurities, and unavoidable voids, and 65 wt%. A Cu—Ga alloy sputtering target is disclosed in which a Cu—Ga alloy phase containing at least% gallium includes at least one of a γ1 phase, a γ2 phase, and a γ3 phase.
日本国特開平10-135495号公報(A)Japanese Laid-Open Patent Publication No. 10-135495 (A) 日本国特開2010-280944号公報(A)Japanese Unexamined Patent Publication No. 2010-280944 (A) 日本国特開2011-241452号公報(A)Japanese Patent Application Laid-Open No. 2011-241452 (A)
 上記の従来技術によるCu-Ga合金スパッタリングターゲットには、以下の課題が残されている。
 即ち、特許文献2に開示されたCu-Ga合金スパッタリングターゲットにおけるCu-Ga合金は、原料を溶融した後に、溶融した原料を急冷凝固することにより製造される。具体的には、40重量%以上60重量%以下のGaを含み、残部がCu及び不可避的不純物からなる混合物を溶解炉中において加熱して溶融させる溶融工程、溶融した混合物を254℃まで冷却し、Cu-Ga合金のγ3相が、溶融させた混合物中に凝固して形成される冷却工程、続いて、冷却工程において温度が254℃に達した後、水冷鋳型又はルツボに対して、200℃以上254℃未満の温度で熱処理を施し、γ3相の間にCu-Ga合金のε相を析出させる熱処理工程、を経ることにより、80重量%以上のGaを含有する偏析相を含むCu-Ga合金(γ3相とε相とを含む)が製造される。
The following problems remain in the above-described conventional Cu—Ga alloy sputtering target.
That is, the Cu—Ga alloy in the Cu—Ga alloy sputtering target disclosed in Patent Document 2 is manufactured by melting the raw material and then rapidly solidifying the molten raw material. Specifically, a melting step of heating and melting a mixture containing 40 wt% or more and 60 wt% or less of Ga and the balance of Cu and inevitable impurities in a melting furnace, cooling the molten mixture to 254 ° C. , A cooling step in which the γ3 phase of the Cu—Ga alloy is solidified in the melted mixture, followed by a temperature of 254 ° C. in the cooling step and then 200 ° C. relative to the water-cooled mold or crucible. By performing a heat treatment at a temperature of less than 254 ° C. and precipitating the ε phase of the Cu—Ga alloy between the γ3 phases, a Cu—Ga containing a segregation phase containing 80 wt% or more of Ga is obtained. Alloys (including γ3 and ε phases) are produced.
 しかしながら、特許文献2によるCu-Ga合金スパッタリングターゲットには、Gaが高濃度に含有されてはいるが、比較的加工性に乏しいGa:80重量%以上含む偏析相が存在するため、スパッタリングターゲットを加工する際に、この偏析相を起点として割れが発生しやすいという問題がある。また、Cu-Ga合金に、Na等のアルカリ金属を添加したスパッタリングターゲットでも、上記と同様な課題がある。 However, the Cu—Ga alloy sputtering target according to Patent Document 2 contains a segregation phase containing Ga: 80% by weight or more, although Ga is contained at a high concentration but relatively poor in workability. When processing, there is a problem that cracks are likely to occur starting from this segregation phase. Further, a sputtering target obtained by adding an alkali metal such as Na to a Cu—Ga alloy has the same problem as described above.
 また、特許文献3に開示されたCu-Ga合金スパッタリングターゲットでは、特許文献2に記載のような偏析相を減らすため、47重量%未満の銅を含む領域の体積のCu-Ga合金材全体の体積に占める割合が2%以下のCu-Ga合金材を提案している。この場合、47重量%未満の銅を含む領域を除いた部分は、32重量%から53重量%以下のガリウムを含む領域となる。即ち、ガリウムの割合が32重量%以上になると脆性を有するγ相が主相となってしまうため、スパッタリングターゲット製造時の加工の際に、割れや欠けが発生しやすいという問題がある。 Further, in the Cu—Ga alloy sputtering target disclosed in Patent Document 3, in order to reduce the segregation phase as described in Patent Document 2, the entire Cu—Ga alloy material having a volume in a region containing less than 47% by weight of copper is used. A Cu—Ga alloy material having a volume ratio of 2% or less is proposed. In this case, the portion excluding the region containing less than 47% by weight of copper becomes a region containing 32% by weight to 53% by weight or less of gallium. That is, when the gallium ratio is 32% by weight or more, the brittle γ phase becomes the main phase, and thus there is a problem that cracks and chips are likely to occur during processing during the production of the sputtering target.
 本願発明は、前述の課題に鑑みてなされたもので、高濃度のGaを含有していても、加工の際に割れ難いCu-Ga合金スパッタリングターゲット及びその製造方法を提供することを目的とする。 The present invention has been made in view of the above-described problems, and an object thereof is to provide a Cu—Ga alloy sputtering target that is difficult to break during processing even if it contains a high concentration of Ga, and a method for manufacturing the same. .
 本願発明は、前記課題を解決するために、以下の態様を採用した。
 (1)本願発明の一態様のスパッタリングターゲット(以下、「本願発明のスパッタリングターゲット」と称する)は、30.0~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成を有し、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散している組織を備えた焼結体からなることを特徴とする。
 (2)前記(1)のスパッタリングターゲットにおいて、前記γ相の平均結晶粒径が、5.0~50.0μmであることを特徴とする。
 (3)前記(1)のスパッタリングターゲットにおいて、前記θ相の平均結晶粒径が、5.0~100.0μmであることを特徴とする。
 (4)前記(1)乃至(3)のいずれかのスパッタリングターゲットにおいて、スパッタ面のX線回折(XRD)パターンで得られた前記γ相に帰属する回折ピークの主ピーク強度に対する前記θ相に帰属する回折ピークの主ピーク強度の比が、0.01~10.0であることを特徴とする。
 (5)前記(1)乃至(4)のいずれかのスパッタリングターゲットにおいて、さらに、Naを0.05~15原子%の範囲内で含有することを特徴とする。
 (6)前記(5)のスパッタリングターゲットにおける前記Naは、フッ化ナトリウム、硫化ナトリウム、セレン化ナトリウムのうち少なくとも1種のNa化合物の状態で含有されていることを特徴とする。
 (7)本願発明の他態様は、前記(1)乃至(4)のいずれかのスパッタリングターゲットの製造方法(以下、「本願発明のスパッタリングターゲットの製造方法と称する」)であり、40.0~67.0原子%、好ましくは42.6~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなるCu-Ga合金粉末であって、X線回折(XRD)パターンで得られた前記γ相に帰属する回折ピークの主ピーク強度に対する前記θ相に帰属する回折ピークの主ピーク強度の比が、0.01~10.0である粉末を、非酸化雰囲気若しくは還元性雰囲気中で、前記主ピーク強度の比が0.5以下の場合には、焼成温度を254℃以上450℃以下、好ましくは254℃以上400℃未満で、主ピーク強度の比が0.5より大きい場合には、焼成温度を254℃未満で焼結して焼結体を作製する工程を有していることを特徴とする。
 (8)本願発明の他態様は、前記(1)乃至(4)のいずれかのスパッタリングターゲットの製造方法(以下、「本願発明のスパッタリングターゲットの製造方法と称する」)であり、γ相(Cu1-xGa:x=0.295~0.426)からなる原料粉とθ相(Cu1-xGa:x=0.646~0.667)からなる原料粉を、θ相からなる原料粉の混合比率を35%以下、好ましくは30%以下で、かつ、30.0~42.6原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成となるように混合した混合粉末を、非酸化雰囲気若しくは還元性雰囲気中で、温度:150~400℃で焼結して焼結体を作製する工程を有していることを特徴とする。
The present invention employs the following aspects in order to solve the above problems.
(1) A sputtering target of one embodiment of the present invention (hereinafter referred to as “sputtering target of the present invention”) contains 30.0 to 67.0 atomic% of Ga, with the balance being Cu and inevitable impurities. A sintered body having a composition and having a structure in which a θ phase of a Cu—Ga alloy is dispersed in a γ phase matrix of a Cu—Ga alloy.
(2) The sputtering target of (1) is characterized in that the average crystal grain size of the γ phase is 5.0 to 50.0 μm.
(3) The sputtering target of (1) is characterized in that the average crystal grain size of the θ phase is 5.0 to 100.0 μm.
(4) In the sputtering target of any one of (1) to (3), the θ phase relative to the main peak intensity of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction (XRD) pattern of the sputtering surface The ratio of the main peak intensity of the assigned diffraction peak is 0.01 to 10.0.
(5) The sputtering target according to any one of (1) to (4), further comprising Na in a range of 0.05 to 15 atomic%.
(6) The Na in the sputtering target of (5) is characterized by being contained in a state of at least one Na compound among sodium fluoride, sodium sulfide, and sodium selenide.
(7) Another aspect of the present invention is a method for manufacturing a sputtering target according to any one of the above (1) to (4) (hereinafter referred to as “the manufacturing method of the sputtering target of the present invention”). A Cu—Ga alloy powder containing 67.0 atomic%, preferably 42.6 to 67.0 atomic% of Ga, with the balance being Cu and inevitable impurities, obtained by an X-ray diffraction (XRD) pattern A powder having a ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase in the range of 0.01 to 10.0 in a non-oxidizing atmosphere or a reducing atmosphere. When the main peak intensity ratio is 0.5 or less, the firing temperature is 254 ° C. or higher and 450 ° C. or lower, preferably 254 ° C. or higher and lower than 400 ° C., and the main peak intensity ratio is higher than 0.5. In Has a step of producing a sintered body by sintering at a firing temperature of less than 254 ° C.
(8) Another aspect of the present invention is a method for producing a sputtering target according to any one of the above (1) to (4) (hereinafter referred to as “the method for producing a sputtering target of the present invention”), and a γ phase (Cu 1-x Ga x : x = 0.295 to 0.426) raw material powder and θ phase (Cu 1-x Ga x : x = 0.646 to 0.667) The mixing ratio of the raw material powder is 35% or less, preferably 30% or less, and contains 30.0 to 42.6 atomic% of Ga, with the balance being a component composition consisting of Cu and inevitable impurities. The mixed powder is sintered in a non-oxidizing atmosphere or a reducing atmosphere at a temperature of 150 to 400 ° C. to produce a sintered body.
 本願発明によれば、以下の効果を奏する。
 即ち、本願発明に係るスパッタリングターゲットによれば、30.0~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成を有する焼結体は、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散している組織を備えているので、Cu-Ga合金焼結体中において、γ相の結晶粒の肥大化を抑制でき、ターゲット加工時の割れ発生を低減することができる。
The present invention has the following effects.
That is, according to the sputtering target of the present invention, the sintered body containing 30.0 to 67.0 atomic% of Ga and the balance of Cu and inevitable impurities is used as the sintered body of the Cu—Ga alloy. Since the phase matrix has a structure in which the θ phase of the Cu—Ga alloy is dispersed, in the sintered body of the Cu—Ga alloy, it is possible to suppress the enlargement of the γ phase crystal grains, and at the time of target processing The generation of cracks can be reduced.
 また、本願発明のスパッタリングターゲットの製造方法によれば、40.0~67.0原子%、好ましくは42.6~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなるCu-Ga合金のアトマイズ粉末を、還元性雰囲気中で温度:150~450℃、好ましくは150~400℃で焼結して焼結体を作製する工程を有し、或いは、γ相(Cu1-xGa:x=0.295~0.426)からなる原料粉とθ相(Cu1-xGa:x=0.646~0.667)からなる原料粉を、30.0~42.6原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成となるように混合した原料粉末を、非酸化雰囲気若しくは還元性雰囲気中で、温度:150~400℃で焼結して焼結体を作製する工程を有しているので、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散している組織を備え、特に好ましくは、前記γ相の平均粒径が、5.0~50.0μmであり、さらに好ましくは、X線回折(XRD)パターンで得られた前記γ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相強度/γ相強度)が、0.01~10.0である焼結体を得ることができる。 Further, according to the method of manufacturing a sputtering target of the present invention, Cu containing 40.0 to 67.0 atomic%, preferably 42.6 to 67.0 atomic% of Ga, with the balance being Cu and inevitable impurities. A step of producing a sintered body by sintering an atomized powder of a Ga alloy in a reducing atmosphere at a temperature of 150 to 450 ° C., preferably 150 to 400 ° C., or a γ phase (Cu 1− The raw material powder made of xGa x : x = 0.295 to 0.426) and the raw material powder made of θ phase (Cu 1-x Ga x : x = 0.646 to 0.667) A raw material powder containing 6 atomic% Ga and mixed so that the balance is composed of Cu and inevitable impurities is sintered at a temperature of 150 to 400 ° C. in a non-oxidizing atmosphere or a reducing atmosphere. Have a process to produce a sintered body Therefore, the γ phase matrix of the Cu—Ga alloy has a structure in which the θ phase of the Cu—Ga alloy is dispersed, and particularly preferably, the average particle diameter of the γ phase is 5.0 to 50. The ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction (XRD) pattern (θ phase intensity / A sintered body having a γ phase strength of 0.01 to 10.0 can be obtained.
 したがって、本願発明の一態様である高濃度Gaを含有するCu-Ga合金スパッタリングターゲットは、加工の際に割れ難くなり、ターゲット製造の歩留まりを向上させることができ、このスパッタリングターゲットを用いてスパッタリング成膜すると、高濃度のGaを含有するCIGS薄膜型太陽電池の光吸収層を成膜でき、光吸収層中の光電変換効率の向上に寄与することができ、発電効率の高い太陽電池を製造することが可能となる。 Therefore, the Cu—Ga alloy sputtering target containing high-concentration Ga, which is one embodiment of the present invention, is difficult to break during processing, and the yield of target production can be improved. When the film is formed, a light absorption layer of a CIGS thin film solar cell containing a high concentration of Ga can be formed, which can contribute to improvement of photoelectric conversion efficiency in the light absorption layer, and manufacture a solar cell with high power generation efficiency. It becomes possible.
Cu-Ga合金に係る状態図である。It is a phase diagram concerning a Cu-Ga alloy. 本願発明の一実施形態のスパッタリングターゲットのX線回折パターンである。It is an X-ray-diffraction pattern of the sputtering target of one Embodiment of this invention. 本願発明の一実施形態のスパッタリングターゲットの組成像の写真である。It is a photograph of the composition image of the sputtering target of one embodiment of the present invention. 比較例のスパッタリングターゲットのX線回折パターンである。It is an X-ray diffraction pattern of the sputtering target of a comparative example. 比較例のスパッタリングターゲットの組成像の写真である。It is a photograph of the composition image of the sputtering target of a comparative example.
 以下、本願発明に係るスパッタリングターゲット及びその製造方法の実施形態を説明する。 Hereinafter, embodiments of the sputtering target and the manufacturing method thereof according to the present invention will be described.
 実施形態のスパッタリングターゲットは、30.0~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成を有しており、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散している組織を備えている焼結体からなることを特徴としている。ここで、γ相マトリックス中にθ相が分散している組織とは、焼結体中において、焼結の際に析出したγ相とθ相とが共存し、γ相及びθ相のうち、一方の相がもう片方の相を囲む状態であって、かつ、それぞれの相がマクロに集合することなく分散している状態のことを指す。 The sputtering target of the embodiment contains 30.0 to 67.0 atomic% of Ga, and the remainder has a component composition consisting of Cu and inevitable impurities. In the γ phase matrix of the Cu—Ga alloy, Cu It is characterized by comprising a sintered body having a structure in which the θ phase of a -Ga alloy is dispersed. Here, the structure in which the θ phase is dispersed in the γ phase matrix means that in the sintered body, the γ phase and the θ phase precipitated during sintering coexist, and among the γ phase and the θ phase, It refers to a state in which one phase surrounds the other phase and each phase is dispersed without being assembled into a macro.
 本実施形態において、Gaの含有量を、30.0~67.0原子%の範囲にする根拠は、Gaの含有量が30.0原子%未満であると、θ相がほとんど消失し、組織が実質的にγ相単相になってしまい、ターゲット加工性が急激に悪くなるからであり、一方、その含有量が、67.0原子%を超えると、θ相は存在するが、純Ga(融点が29.6℃)が生成してしまい、ターゲット切削加工中の熱によって、Gaの溶け出しが発生し、この溶け出したGaを起点として、ターゲット割れが発生してしまうからである。 In the present embodiment, the basis for setting the Ga content in the range of 30.0 to 67.0 atomic% is that when the Ga content is less than 30.0 atomic%, the θ phase is almost eliminated, and the structure Is substantially a single phase of γ phase, and the target processability is abruptly deteriorated. On the other hand, when the content exceeds 67.0 atomic%, the θ phase exists, but pure Ga is present. This is because (melting point is 29.6 ° C.) is generated, Ga is melted by heat during target cutting, and target cracks are generated starting from the melted Ga.
 なお、本実施形態における前記γ相及びθ相は、本明細書に添付した図1に示されるCu-Ga合金に係る状態図[Binary Alloy Phase Diagrams(第2版),Copyright 1990 by ASM International(R), ISBN : 0-87170-405-6の1410頁に記載されているP. R. SubramanianとD. E. LaughlinとによるCu-Ga系の項目を参照]におけるγ相(Cu1-xGa:x=0.295~0.426)及びθ相(Cu1-xGa:x=0.646~0.667)にそれぞれ対応している。ここで、本実施形態における前記γ相は、図1に示される状態図におけるγとγ1~γ3を含む。 In the present embodiment, the γ phase and the θ phase are phase diagrams related to the Cu—Ga alloy shown in FIG. 1 attached to this specification [Binary Alloy Phase Diagrams (2nd edition), Copyright 1990 by ASM International ( R), ISBN: 0-87170-405-6, page 1410 of PR Subramanian and DE Laughlin (see Cu-Ga system item)] in the γ phase (Cu 1-x Ga x : x = 0 .295 to 0.426) and the θ phase (Cu 1-x Ga x : x = 0.646 to 0.667). Here, the γ phase in the present embodiment includes γ and γ1 to γ3 in the state diagram shown in FIG.
 ここで、本実施形態のスパッタリングターゲットの代表例として、Gaの含有量が50.0原子%のCu-Ga合金のアトマイズ粉を、10L/minでArガスを流しつつ、50MPaの圧力、165℃の焼成温度で2時間保持してホットプレス焼結して得たCu-Ga合金焼結体からなるスパッタリングターゲットを例にとり、その組織を図2と図3を用いて説明する。図2は、上記のスパッタリングターゲットにX線回折(XRD)による分析を実施して得たX線回折(XRD)パターンである。図3は、上記のスパッタリングターゲットに電子線プローブマイクロ分析(EPMA)を実施し、得られた組成像(COMPO像)の写真である。 Here, as a typical example of the sputtering target of the present embodiment, atomized powder of a Cu—Ga alloy having a Ga content of 50.0 atomic% is applied at a pressure of 50 MPa and 165 ° C. while flowing Ar gas at 10 L / min. An example of a sputtering target made of a Cu—Ga alloy sintered body obtained by hot press sintering while being held at a firing temperature of 2 hours will be described with reference to FIGS. 2 and 3. FIG. 2 is an X-ray diffraction (XRD) pattern obtained by analyzing the above-described sputtering target by X-ray diffraction (XRD). FIG. 3 is a photograph of a composition image (COMPO image) obtained by performing electron probe microanalysis (EPMA) on the above sputtering target.
 図2のXRDパターンからわかるように、上記のスパッタリングターゲットから、Cu-Ga合金のγ相(CuGa相)に帰属する回折ピークとθ相(CuGa相)に帰属する回折ピークの両方が観察された。γ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相強度/γ相強度:「θ相の割合」とも称す。)は、0.80であった。また、図3のCOMPO像の写真から、上記のスパッタリングターゲットは、γ相とθ相との2相がそれぞれ分散した状態で存在していることが明確にわかる。また、図3に示したCOMPO像の写真においては、最も白い部分がGaの含有量が相対的に高い領域を示しており、同図中で矢示したように、淡い灰色の領域が、θ相であり、濃い灰色の領域が、γ相である。
 以上から、上記のスパッタリングターゲットは、γ相のマトリックス中に、相対的にGaが多く含有されているθ相が存在する結晶組織を有していることが分かる。なお、スパッタリングターゲット中に、NaあるいはKが添加された場合でも、上記と同様に、その結晶組織は、γ相とθ相との2相共存組織を有する。
As can be seen from the XRD pattern in FIG. 2, both the diffraction peak attributed to the γ phase (Cu 9 Ga 4 phase) and the diffraction peak attributed to the θ phase (CuGa 2 phase) of the Cu—Ga alloy are obtained from the above sputtering target. Was observed. The ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase (θ phase intensity / γ phase intensity: also referred to as “ratio of θ phase”) is 0.80. there were. In addition, it can be clearly seen from the photograph of the COMPO image in FIG. 3 that the above-described sputtering target exists in a state where two phases of γ phase and θ phase are dispersed. Moreover, in the photograph of the COMPO image shown in FIG. 3, the whitest part shows the area | region where content of Ga is relatively high, and as shown by the arrow in the same figure, the light gray area | region is (theta). The dark gray area is the γ phase.
From the above, it can be seen that the above sputtering target has a crystal structure in which a θ phase containing a relatively large amount of Ga exists in a γ phase matrix. Even when Na or K is added to the sputtering target, the crystal structure has a two-phase coexistence structure of γ phase and θ phase as described above.
 スパッタリングターゲットの結晶組織中に、γ相とθ相との2相が共存する理由は、原料のCu-Ga合金粉末のX線回折(XRD)パターンで得られた前記θ相に帰属する回折ピークの主ピーク強度と前記γ相に帰属する回折ピークの主ピーク強度との比が、0.01~10.0であるためである。原料のCu-Ga合金中のθ相が少ない場合、具体的には、上記θ相の割合が0.5以下の場合、焼成温度を254℃以上に設定することで、焼成の際にCu-Ga合金粉末からθ相の液相が出現し、所謂、液相焼結となるため、緻密化が容易に起こり、低温ホットプレスによる粉末焼結でありながら高密度な焼結体からなるスパッタリングターゲットが得られる。その焼結体が冷却される過程において、254℃付近でθ相の析出が起こる。原料のCu-Ga合金中のθ相が多い場合、具体的には、上記θ相の割合が0.5を超える場合、焼成温度を254℃未満に設定することで、θ相からの液相の析出がないため、原料のCu-Ga合金中のθ相が保持される。このとき、焼成温度を254℃以上に設定すると、θ相からの液相量が多すぎるため、焼結体の形状を保持することが困難である。 The reason why two phases of γ phase and θ phase coexist in the crystal structure of the sputtering target is that the diffraction peak attributed to the θ phase obtained by the X-ray diffraction (XRD) pattern of the raw material Cu—Ga alloy powder. This is because the ratio between the main peak intensity of the diffraction peak and the main peak intensity of the diffraction peak attributed to the γ phase is 0.01 to 10.0. When the θ phase in the raw material Cu—Ga alloy is small, specifically, when the proportion of the θ phase is 0.5 or less, the firing temperature is set to 254 ° C. or more, so that Cu— A sputtering target consisting of a high-density sintered body while being powder-sintered by low-temperature hot pressing, because the θ-phase liquid phase appears from the Ga alloy powder and so-called liquid-phase sintering occurs. Is obtained. In the process of cooling the sintered body, precipitation of the θ phase occurs around 254 ° C. When there are many θ phases in the raw material Cu—Ga alloy, specifically, when the proportion of the θ phases exceeds 0.5, the liquid phase from the θ phase can be set by setting the firing temperature to less than 254 ° C. Therefore, the θ phase in the raw material Cu—Ga alloy is retained. At this time, if the firing temperature is set to 254 ° C. or higher, the amount of liquid phase from the θ phase is too large, and it is difficult to maintain the shape of the sintered body.
 また、前記θ相の割合が0.5を超える場合、即ち、θ相(Cu1-xGa:x=0.646~0.667)からなる原料粉の場合においては、原料のCu-Ga合金中にθ相を含まない、即ち、γ相(Cu1-xGa:x=0.295~0.426)からなる第二のCu-Ga合金原料粉とを、30.0~42.6原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成となるように混合した原料粉を用いることで、θ相からなるCu-Ga合金原料粉から、γ相からなるCu-Ga合金原料粉へのGaの拡散が起こり、Gaの液相の析出を抑制することが可能となり、254℃以上の焼結温度においても焼結体を得ることができる。このとき、前記θ相の割合が0.5を超えるCu-Ga合金原料粉の混合比率は30%以下であることが好ましい。混合比率が30%を超えると、θ相からなるCu-Ga合金原料粉からγ相からなるCu-Ga合金原料粉へのGaの拡散があったとしても、θ相からの液相量が多すぎるため焼結体の形状を保持することが困難である。
 γ相とθ相の2相が共存する利点は、θ相の存在によって、γ相の結晶粒の肥大化が抑制され、ターゲット組織中の平均結晶粒径が小さくなり、スパッタリングターゲットの加工の際に割れ難いものとなる。
When the ratio of the θ phase exceeds 0.5, that is, in the case of the raw material powder composed of the θ phase (Cu 1-x Ga x : x = 0.646 to 0.667), the raw material Cu— A second Cu—Ga alloy raw material powder containing no θ phase in the Ga alloy, ie, a γ phase (Cu 1−x Ga x : x = 0.295 to 0.426), By using raw material powder containing 42.6 atomic% Ga and mixed so that the balance is composed of Cu and inevitable impurities, the raw material powder is composed of the γ phase from the Cu—Ga alloy raw material powder composed of the θ phase. Ga diffusion into the Cu—Ga alloy raw material powder occurs, so that precipitation of the Ga liquid phase can be suppressed, and a sintered body can be obtained even at a sintering temperature of 254 ° C. or higher. At this time, the mixing ratio of the Cu—Ga alloy raw material powder with the θ phase ratio exceeding 0.5 is preferably 30% or less. When the mixing ratio exceeds 30%, the amount of liquid phase from the θ phase is large even if Ga diffuses from the Cu—Ga alloy raw material powder consisting of the θ phase to the Cu—Ga alloy raw material powder consisting of the γ phase. Therefore, it is difficult to maintain the shape of the sintered body.
The advantage of the coexistence of two phases, γ phase and θ phase, is that the presence of the θ phase suppresses the enlargement of the crystal grains of the γ phase, reduces the average crystal grain size in the target structure, and allows the sputtering target to be processed. It is difficult to break.
 以上の本実施形態のスパッタリングターゲットと比較するための例として、Gaの含有量が33.0原子%のCu-Ga合金のアトマイズ粉を、10L/minでArガスを流しつつ、60MPaの圧力、700℃の焼成温度で2時間保持してホットプレス焼結したCu-Ga合金焼結体について、X線回折(XRD)による分析を実施し、その測定結果を、図4のXRDパターンを示し、更には、電子線プローブマイクロ分析(EPMA)を実施し、得られた組成像(COMPO像)の写真を、図5に示した。図4のXRDパターンでは、Cu-Ga合金のγ相に帰属する回折ピークが観察されるのみであり、図5のCOMPO像の写真でも、画像全体が灰色を呈しており、濃淡がほとんど見られない。なお、像中に存在する黒点は、ポアである。これらのことから、この例によるスパッタリングターゲットにおける焼結体では、そのマトリックスの主相は、γ相の単一相で形成され、相対的にGaが多く含有されているθ相が存在していないことが分かる。 As an example for comparison with the sputtering target of the present embodiment as described above, an atomized powder of a Cu—Ga alloy having a Ga content of 33.0 atomic%, a pressure of 60 MPa while flowing Ar gas at 10 L / min, A Cu—Ga alloy sintered body that was held at a firing temperature of 700 ° C. for 2 hours and hot-press-sintered was analyzed by X-ray diffraction (XRD), and the measurement results are shown in the XRD pattern of FIG. Furthermore, the electron-beam probe microanalysis (EPMA) was implemented and the photograph of the obtained composition image (COMPO image) was shown in FIG. In the XRD pattern of FIG. 4, only the diffraction peak attributed to the γ phase of the Cu—Ga alloy is observed, and even in the photograph of the COMPO image of FIG. Absent. A black spot existing in the image is a pore. Therefore, in the sintered body of the sputtering target according to this example, the main phase of the matrix is formed of a single phase of γ phase, and there is no θ phase containing a relatively large amount of Ga. I understand that.
 また、本実施形態のスパッタリングターゲットでは、前記γ相の平均結晶粒径が、5.0~50.0μmであり、前記θ相の平均結晶粒径が、5.0~100.0μmであり、さらには、X線回折(XRD)パターンで得られたγ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相強度/γ相強度)が、0.01~10.0の範囲であることが好ましい。
 即ち、本実施形態のスパッタリングターゲットにおけるγ相の平均結晶粒径が、50.0μmを、更には、θ相の平均結晶粒径が、100.0μmを超えると、スパッタリングターゲット製造後の加工の際に、チッピング(割れや欠け)が発生しやすくなる。さらに、そのスパッタリングターゲット中で、γ相とθ相との2相が共存することを表すためのθ相割合を、0.01~10.0の範囲とすると、θ相の存在によって、γ相の結晶粒の肥大化が抑制されるので、スパッタリングターゲットの加工の際に割れ難いものとすることができる。
In the sputtering target of the present embodiment, the average crystal grain size of the γ phase is 5.0 to 50.0 μm, the average crystal grain size of the θ phase is 5.0 to 100.0 μm, Furthermore, the ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction (XRD) pattern (θ phase intensity / γ phase intensity) is A range of 0.01 to 10.0 is preferable.
That is, when the average crystal grain size of the γ phase in the sputtering target of this embodiment exceeds 50.0 μm, and further the average crystal grain size of the θ phase exceeds 100.0 μm, the processing after the sputtering target is manufactured. In addition, chipping (breaking or chipping) is likely to occur. Furthermore, if the θ phase ratio for representing the coexistence of two phases of the γ phase and the θ phase in the sputtering target is in the range of 0.01 to 10.0, the presence of the θ phase causes the γ phase to exist. Since the enlargement of the crystal grains is suppressed, it can be made difficult to break when the sputtering target is processed.
 さらに、本実施形態のスパッタリングターゲットは、太陽電池の光吸収層となるCIGS膜を形成するときに使用され得るので、その光電変換効率を高めるため、このスパッタリングターゲットに、Naを、0.05~15原子%含有させ、さらには、そのNaを、フッ化ナトリウム、硫化ナトリウム、セレン化ナトリウムのうち少なくとも1種のNa化合物の状態で含有させてもよい。このスパッタリングターゲットに、Naの代わりに、Kを、0.05~15原子%含有させ、そのKを、フッ化カリウム、塩化カリウム、臭化カリウム、ヨウ化カリウム、硫化カリウム、セレン化カリウム、ニオブ酸カリウムのうち少なくとも1種のK化合物の状態で含有させることもできる。また、NaとKは同時に添加してもよく、その場合NaとKの合計が0.05~15原子%とする。 Furthermore, since the sputtering target of this embodiment can be used when forming a CIGS film that becomes a light absorption layer of a solar cell, Na is added to the sputtering target in an amount of 0.05 to 0.05 in order to increase its photoelectric conversion efficiency. The Na may be contained in an amount of 15 atomic%, and the Na may be contained in the form of at least one Na compound among sodium fluoride, sodium sulfide, and sodium selenide. In this sputtering target, 0.05 to 15 atomic% of K is contained instead of Na, and the K is contained in potassium fluoride, potassium chloride, potassium bromide, potassium iodide, potassium sulfide, potassium selenide, niobium. It can also be made to contain in the state of at least 1 sort (s) of K compound among potassium acid. Na and K may be added simultaneously. In this case, the total of Na and K is 0.05 to 15 atomic%.
 次に、本実施形態に係るスパッタリングターゲットの製造方法について説明する。
 本実施形態に係るスパッタリングターゲットの製造方法は、上記実施形態のスパッタリングターゲットを製造する方法であって、40.0~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなるCu-Ga合金粉末であって、X線回折(XRD)パターンで得られたγ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相強度/γ相強度)が、0.01~10.0である粉末を、非酸化性雰囲気若しくは還元性雰囲気中で、前記主ピーク強度の比が0.5以下の場合には、焼成温度を254℃以上450℃以下で、主ピーク強度の比が0.5より大きい場合には、焼成温度を254℃未満で焼結して焼結体を作製する工程を有していることを特徴としている。
 即ち、このスパッタリングターゲットの製造方法では、Cu-Ga合金粉末を用いることで、焼結体中の結晶粒径を調整しやすくした。また、X線回折(XRD)パターンで得られたγ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相強度/γ相強度)を、0.01~10.0にし、さらに、そのスパッタリングターゲットに係る焼結体を得るときの焼結温度を、150~450℃の範囲としたので、その焼結体において、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散した組織とすることができ、前記γ相の平均結晶粒径を、50.0μm以下にすることができる。
Next, the manufacturing method of the sputtering target which concerns on this embodiment is demonstrated.
The method for producing a sputtering target according to this embodiment is a method for producing the sputtering target according to the above embodiment, which contains 40.0 to 67.0 atomic% of Ga, with the balance being Cu and inevitable impurities. -Ga alloy powder, the ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction (XRD) pattern (θ phase intensity / γ If the ratio of the main peak intensities is 0.5 or less in a non-oxidizing atmosphere or a reducing atmosphere, the firing temperature is 254 ° C. or more. When the ratio of main peak intensities is 450 ° C. or less and larger than 0.5, the method has a step of sintering at a firing temperature of less than 254 ° C. to produce a sintered body.
That is, in this sputtering target manufacturing method, the crystal grain size in the sintered body can be easily adjusted by using Cu—Ga alloy powder. The ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction (XRD) pattern (θ phase intensity / γ phase intensity) is 0 Further, the sintering temperature for obtaining the sintered body related to the sputtering target was set in the range of 150 to 450 ° C., so that the γ phase of the Cu—Ga alloy was used in the sintered body. A structure in which the θ phase of the Cu—Ga alloy is dispersed in the matrix can be formed, and the average crystal grain size of the γ phase can be made 50.0 μm or less.
 さらに、本実施形態に係るスパッタリングターゲットの別の製造方法は、上記のスパッタリングターゲットを製造する方法であって、γ相(Cu1-xGa:x=0.295~0.426)からなる原料粉とθ相(Cu1-xGa:x=0.646~0.667)からなる原料粉を、30.0~42.6原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成となるように混合した混合粉末を、非酸化雰囲気若しくは還元性雰囲気中で、温度:150~400℃で焼結して焼結体を作製する工程を有していることを特徴としている。
 即ち、このスパッタリングターゲットの製造方法では、γ相(Cu1-xGax:=0.295~0.426)からなる原料粉とθ相(Cu1-xGa:x=0.646~0.667)からなる原料粉を用いることで、焼結体において、30.0~42.6原子%のGaを含有した組成においても、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相をより分散した組織とすることができ、前記γ相の平均結晶粒径を、50.0μm以下にすることができる。
Furthermore, another method for producing a sputtering target according to the present embodiment is a method for producing the above-described sputtering target, which comprises a γ phase (Cu 1-x Ga x : x = 0.295 to 0.426). Raw material powder consisting of raw material powder and θ phase (Cu 1-x Ga x : x = 0.646 to 0.667) contains 30.0 to 42.6 atomic% of Ga, with the balance being Cu and inevitable impurities Characterized in that it has a step of sintering the mixed powder mixed so as to have a component composition consisting of the above in a non-oxidizing atmosphere or a reducing atmosphere at a temperature of 150 to 400 ° C. to produce a sintered body. It is said.
That is, in this sputtering target manufacturing method, the raw material powder composed of the γ phase (Cu 1-x Gax: x = 0.295 to 0.426) and the θ phase (Cu 1−x Ga x : x = 0.646− By using the raw material powder consisting of 0.667), even in a composition containing 30.0 to 42.6 atomic% Ga in the sintered body, Cu—Ga is included in the γ phase matrix of the Cu—Ga alloy. The θ phase of the alloy can be made more dispersed, and the average crystal grain size of the γ phase can be made 50.0 μm or less.
 本実施形態のCu-Ga二元系スパッタリングターゲットの製造手順は、例えば、合金粉末として、Cu金属塊と、Ga金属塊と、これらを所定量に秤量し、それぞれを坩堝内で溶解した後、ガスアトマイズ法により、原料粉末を作製する工程と、該原料粉末と必要に応じてNa化合物原料粉、K化合物原料粉とを非酸化雰囲気で混合させる工程と、該原料粉末を非酸化雰囲気若しくは還元性雰囲気中で、低温で焼結させる工程と、該焼結工程で得られた焼結体の表面を切削する工程と、を有している。
 ここで、原料粉末を作製する工程では、原料粉末であるCu-Ga合金アトマイズ粉末が、カーボン坩堝にCu金属塊と、Ga金属塊とを所定の組成比でそれぞれ充填し、Arガスによるガスアトマイズ法で調製される。
 低温で焼結させる工程では、ホットプレス、熱間等方加圧焼結及び常圧焼結のいずれかが用いられ、その焼結する時の保持温度を、150~450℃の範囲内で設定した。非酸化雰囲気は、Ar雰囲気、真空雰囲気などの酸素を含まない雰囲気をいう。還元性雰囲気は、H、COなどの還元性ガスを含む雰囲気をいう。
The manufacturing procedure of the Cu—Ga binary sputtering target of the present embodiment is, for example, as an alloy powder, Cu metal lump, Ga metal lump, and these are weighed to a predetermined amount, and each is melted in a crucible, A step of producing a raw material powder by a gas atomizing method, a step of mixing the raw material powder with a Na compound raw material powder and a K compound raw material powder as required in a non-oxidizing atmosphere, and the raw material powder in a non-oxidizing atmosphere or reducing property It has the process of sintering at low temperature in atmosphere, and the process of cutting the surface of the sintered compact obtained by this sintering process.
Here, in the step of producing the raw material powder, the Cu—Ga alloy atomized powder as the raw material powder is filled with a Cu metal lump and a Ga metal lump in a carbon crucible at a predetermined composition ratio, and a gas atomizing method using Ar gas. It is prepared with.
In the process of sintering at a low temperature, any one of hot press, hot isostatic pressing and atmospheric sintering is used, and the holding temperature at the time of sintering is set within a range of 150 to 450 ° C. did. The non-oxidizing atmosphere refers to an atmosphere containing no oxygen such as an Ar atmosphere or a vacuum atmosphere. The reducing atmosphere refers to an atmosphere containing a reducing gas such as H 2 or CO.
 焼結体の表面を切削する工程では、得られた焼結体の表面部と外周部とを旋盤加工して直径50mm、厚み6mmのスパッタリングターゲットを作製する。 In the step of cutting the surface of the sintered body, the surface portion and the outer peripheral portion of the obtained sintered body are turned to produce a sputtering target having a diameter of 50 mm and a thickness of 6 mm.
 次に、加工後のスパッタリングターゲットを、Inを半田としてCu又はsus(ステンレス)またはその他金属(例えば、Mo)からなるバッキングプレートにボンディングし、スパッタリングに供する。
 なお、加工済みのターゲットを保管する際には、酸化、吸湿を防止するため、ターゲット全体を真空パック又は不活性ガス置換したパックを施すことが好ましい。
Next, the processed sputtering target is bonded to a backing plate made of Cu or sus (stainless steel) or other metal (for example, Mo) using In as a solder, and is used for sputtering.
In addition, when storing the processed target, it is preferable to apply a vacuum pack or a pack obtained by replacing the entire target with a vacuum in order to prevent oxidation and moisture absorption.
 このように作製したスパッタリングターゲットは、Arガスをスパッタガスとして用いるDCマグネトロンスパッタリング装置に供する。このときの直流(DC)スパッタリングは、パルス電圧を付加するパルスDC電源を用いることでもよいし、パルスなしのDC電源でも可能である。 The thus produced sputtering target is subjected to a DC magnetron sputtering apparatus using Ar gas as a sputtering gas. In this case, direct current (DC) sputtering may be performed using a pulsed DC power source to which a pulse voltage is applied or a DC power source without a pulse.
 本実施形態では、上記の製造手順により、Cu-Ga合金の焼結体におけるγ相マトリックス中に、θ相を分散させるようにした。このγ相とθ相との2相が共存する理由は、原料のCu-Ga合金粉末のX線回折(XRD)パターンで得られたγ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相強度/γ相強度=θ相の割合)が、0.01~10.0であるためである。原料のCu-Ga合金中のθ相が少ない場合、具体的には、上記θ相の割合が0.5以下の場合、焼成温度を254℃以上に設定することで、焼成の際にCu-Ga合金粉末からθ相の液相が出現し、所謂、液相焼結となるため、緻密化が容易に起こり、低温ホットプレスによる粉末焼結でありながら高密度な焼結体が得られる。その焼結体が冷却される過程において、254℃付近で、θ相の析出が起こる。原料のCu-Ga合金中のθ相が多い場合、具体的には、上記θ相の割合が0.5を超える場合、焼成温度を254℃未満に設定することで、θ相からの液相の析出がないため、原料のCu-Ga合金中のθ相が保持される。このとき、焼成温度を254℃以上に設定すると、θ相からの液相量が多すぎるため、焼結体の形状を保持することが困難である。前述の「Binary Alloy Phase Diagrams(第2版)」に記載されたCu-Ga系状態図によると、この相分離はGaの原子比率が42.6%以上の場合には必ず起こると予想される。また、Gaの原子比率が30.0~42.6%の場合においても、原料粉としてγ相(Cu1-xGa:x=0.295~0.426)からなる原料粉とθ相(Cu1-xGa:x=0.646~0.667)からなる原料粉を用いることで、Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散した組織とすることができる。2相共存の利点は、θ相の存在によって、γ相の結晶粒の肥大化が抑制され、ターゲット組織の平均粒径が小さくなり、スパッタリングターゲットの加工の際に割れ難いものとなる。 In the present embodiment, the θ phase is dispersed in the γ phase matrix in the sintered body of the Cu—Ga alloy by the above manufacturing procedure. The reason why the two phases of γ phase and θ phase coexist is that the θ phase with respect to the main peak intensity of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction (XRD) pattern of the raw material Cu—Ga alloy powder. This is because the ratio of the main peak intensity of the assigned diffraction peak (θ phase intensity / γ phase intensity = θ phase ratio) is 0.01 to 10.0. When the θ phase in the raw material Cu—Ga alloy is small, specifically, when the proportion of the θ phase is 0.5 or less, the firing temperature is set to 254 ° C. or more, so that Cu— Since a liquid phase of the θ phase appears from the Ga alloy powder and so-called liquid phase sintering is performed, densification easily occurs, and a high-density sintered body can be obtained while performing powder sintering by low-temperature hot pressing. In the process of cooling the sintered body, θ phase precipitation occurs at around 254 ° C. When there are many θ phases in the raw material Cu—Ga alloy, specifically, when the proportion of the θ phases exceeds 0.5, the liquid phase from the θ phase can be set by setting the firing temperature to less than 254 ° C. Therefore, the θ phase in the raw material Cu—Ga alloy is retained. At this time, if the firing temperature is set to 254 ° C. or higher, the amount of liquid phase from the θ phase is too large, and it is difficult to maintain the shape of the sintered body. According to the Cu—Ga phase diagram described in “Binary Alloy Phase Diagrams (2nd edition)” described above, this phase separation is expected to occur whenever the atomic ratio of Ga is 42.6% or more. . Further, even when the atomic ratio of Ga is 30.0 to 42.6%, the raw material powder composed of a γ phase (Cu 1-x Ga x : x = 0.295 to 0.426) as a raw material powder and the θ phase By using a raw material powder made of (Cu 1-x Ga x : x = 0.646 to 0.667), a structure in which the θ phase of the Cu—Ga alloy is dispersed in the γ phase matrix of the Cu—Ga alloy, and can do. The advantage of the two-phase coexistence is that the presence of the θ phase suppresses the enlargement of the crystal grains of the γ phase, reduces the average grain size of the target structure, and makes it difficult to break during sputtering target processing.
 次に、本実施形態に係るスパッタリングターゲット及びその製造方法について、実施例及び比較例により、具体的に説明する。 Next, the sputtering target and the manufacturing method thereof according to the present embodiment will be specifically described with reference to examples and comparative examples.
 先ず、4N(純度99.99%)のCu金属塊と、4N(純度99.99%)のGa金属塊を用意した。表1に示されるような成分組成で全体重量が1200gとなるように秤量し、それぞれをカーボン坩堝に充填して溶解した後、Arガスによるガスアトマイズ法により、Ga含有量が調整された原料粉A及び原料粉Bを作製し、これらの原料粉末を125μmの篩にかけて分級した。ガスアトマイズの条件として、溶解時の温度を1000~1200℃、噴射ガス圧を28kgf/cm、ノズル径を1.5mmとした。 First, a 4N (purity 99.99%) Cu metal block and a 4N (purity 99.99%) Ga metal block were prepared. Raw material powder A with a Ga content adjusted by a gas atomization method using Ar gas, after weighing each component composition as shown in Table 1 to a total weight of 1200 g, filling each in a carbon crucible and dissolving it And raw material powder B was produced, and these raw material powders were classified by passing through a 125 μm sieve. As gas atomization conditions, the melting temperature was 1000 to 1200 ° C., the injection gas pressure was 28 kgf / cm 2 , and the nozzle diameter was 1.5 mm.
 実施例1、3、5、9、15、16では、上述のガスアトマイズ法により作製され、θ相(Cu1-xGa:x=0.646~0.667)が、表1に記載のθ相割合で、γ相マトリックス中に分散された組織を有する原料粉Aを使用してCuGa原料粉末とした(混合比率100%)。
 実施例2、4、10、13では、θ相が、表1に記載のθ相割合で、γ相マトリックス中に分散された組織を有する原料粉Aと、γ相(Cu1-xGa:x=0.295~0.426)の単一相からなる原料粉Bとを、表1に記載の混合比率で秤量した後、ロッキングミキサーにより混合し、CuGa原料粉末を得た。ロッキングミキサーによる混合条件は、回転数72rpm、混合時間を30分とした。
 実施例6、7では、原料粉Aと表2に示されるNa添加剤とを、表1に記載の原料粉Aと表2に記載のNa添加剤の混合比率で秤量した後、ロッキングミキサーにより混合し、原料粉末を得た。また、実施例8、11では、原料粉Aと原料粉Bとを、表1に記載の混合比率にて秤量してロッキングミキサーにより混合して得た混合物に、表2に示されるNa添加剤を、表2に記載の混合比率にて加えた後、ロッキングミキサーにより混合し、CuGa原料粉末を得た。Na添加剤としては、3N(純度99.9%)のNa化合物粉末を用いた。
 実施例14、19~23では、原料粉Aと表2に示されるK添加剤とを、表1に記載の原料粉Aの混合比率と表2に記載のK添加剤の混合比率にて秤量し、ロッキングミキサーにより混合して、原料粉末を得た。
 実施例17では、原料粉Aと原料粉Bと表2に示されるK添加剤とを、表1に示される原料粉Aと原料粉Bの混合比率と表2に示されるK添加剤の混合比率で秤量した後、ロッキングミキサーにより混合し、原料粉末を得た。
 実施例18では、原料粉Aと表2に示されるNa添加剤とK添加剤とを、表1に示される原料粉Aの混合比率と表2に示されるNa添加剤とK添加剤の混合比率で秤量し、ロッキングミキサーにより混合して、原料粉末を得た。
In Examples 1, 3, 5, 9, 15, and 16, they were prepared by the gas atomization method described above, and the θ phase (Cu 1-x Ga x : x = 0.646 to 0.667) is described in Table 1. A CuGa raw material powder was prepared using a raw material powder A having a structure dispersed in a γ phase matrix at a θ phase ratio (mixing ratio 100%).
In Examples 2, 4, 10, and 13, the raw material powder A having a structure in which the θ phase is the θ phase ratio shown in Table 1 and dispersed in the γ phase matrix, and the γ phase (Cu 1-x Ga x : X = 0.295 to 0.426) raw material powder B consisting of a single phase was weighed at the mixing ratio shown in Table 1, and then mixed with a rocking mixer to obtain CuGa raw material powder. The mixing conditions using the rocking mixer were a rotational speed of 72 rpm and a mixing time of 30 minutes.
In Examples 6 and 7, the raw material powder A and the Na additive shown in Table 2 were weighed at the mixing ratio of the raw material powder A shown in Table 1 and the Na additive shown in Table 2, and then rocked with a rocking mixer. The raw material powder was obtained by mixing. Moreover, in Examples 8 and 11, Na additive shown in Table 2 was added to the mixture obtained by weighing the raw material powder A and the raw material powder B at the mixing ratio shown in Table 1 and mixing them with a rocking mixer. Were added at a mixing ratio shown in Table 2 and then mixed with a rocking mixer to obtain a CuGa raw material powder. As the Na additive, 3N (purity 99.9%) Na compound powder was used.
In Examples 14 and 19 to 23, the raw material powder A and the K additive shown in Table 2 were weighed at the mixing ratio of the raw material powder A shown in Table 1 and the mixing ratio of the K additive shown in Table 2. And mixed with a rocking mixer to obtain a raw material powder.
In Example 17, the raw material powder A, the raw material powder B, and the K additive shown in Table 2 were mixed, the mixing ratio of the raw material powder A and the raw material powder B shown in Table 1 and the mixing of the K additive shown in Table 2 After weighing in proportion, mixing was performed with a rocking mixer to obtain a raw material powder.
In Example 18, the raw material powder A, the Na additive and the K additive shown in Table 2, the mixing ratio of the raw material powder A shown in Table 1, and the Na additive and K additive shown in Table 2 were mixed. Weighed at a ratio and mixed with a rocking mixer to obtain a raw material powder.
 上記混合で得られたCuGa原料粉末について、成分組成の分析を行った結果が、表2の「CuGa原料粉組成」欄に示されている。ここで、Cuに関しては、「残部」と表記したが、この残部には、F、Cl、Br、I、S、Se、Nb、Oの成分が除かれている。 The results of analyzing the component composition of the CuGa raw material powder obtained by the above mixing are shown in the “CuGa raw material powder composition” column of Table 2. Here, Cu is described as “remainder”, but the components of F, Cl, Br, I, S, Se, Nb, and O are removed from this remainder.
 次いで、作製された原料粉末を100g秤量し、表3に示される焼結条件に従って焼結し、Cu-Ga合金焼結体を得た。得られた焼結体の表面部と外周部とを旋盤加工して直径50mm、厚み6mmの実施例1~23のスパッタリングターゲットを作製した。なお、上記θ相の割合の求め方については、後述するが、Iobs(θ相)をθ相(102)面の測定ピーク強度、Iobs(γ相)をγ相(330)面の測定ピーク強度とすると、Iobs(θ相)/Iobs(γ相)で求められる。また、実施例14は、Na化合物の代わりに、K化合物を添加する場合の代表例を示しており、Naの添加の場合と同様に、ロッキングミキサーにより混合する際に、先に得られたCuGa原料粉末と、表2に示される混合比率によるK化合物粉末(KF)とを用意して混合した。実施例18の場合も、同様にして、Na化合物粉末(NaF)とK化合物粉末(KCl)とを用意し、混合した。 Next, 100 g of the prepared raw material powder was weighed and sintered according to the sintering conditions shown in Table 3 to obtain a Cu—Ga alloy sintered body. The surface portion and the outer peripheral portion of the obtained sintered body were turned to produce sputtering targets of Examples 1 to 23 having a diameter of 50 mm and a thickness of 6 mm. The method for obtaining the ratio of the θ phase will be described later. I obs (θ phase) is the measurement peak intensity of the θ phase (102) plane, and I obs (γ phase) is the measurement of the γ phase (330) plane. Assuming the peak intensity, it is obtained by I obs (θ phase) / I obs (γ phase). In addition, Example 14 shows a typical example in the case of adding a K compound instead of the Na compound. Similarly to the case of addition of Na, when mixing with a rocking mixer, the CuGa obtained previously was used. A raw material powder and a K compound powder (KF) having a mixing ratio shown in Table 2 were prepared and mixed. In the case of Example 18, Na compound powder (NaF) and K compound powder (KCl) were similarly prepared and mixed.
 〔比較例〕
 一方、比較例として、上記実施例の範囲から外れた条件に基づいて焼結された焼成体を得て、比較例1~4のCu-Ga合金スパッタリングターゲットを作製した。
 比較例1は、原料粉AにおけるGaの含有量が実施例の場合に比較して少なく、かつ、θ相割合が低く、本願発明のスパッタリングターゲットの製造方法における温度範囲外の高い温度でホットプレスした場合であり、比較例2は、原料粉AにおけるGaの含有量が実施例の場合に比較して多く、γ相が無い場合であり、そして、比較例3は、原料粉A及び原料粉Bを使用した場合であるが、原料粉Bの混合割合が高く、CuGa原料粉末におけるGaの含有量が、実施例の場合に比較して少ない場合である。また、比較例4は、原料粉A及び原料粉Bを使用した場合であるが、原料粉Aの混合割合が高い場合である。
[Comparative Example]
On the other hand, as a comparative example, a fired body sintered based on conditions outside the range of the above examples was obtained, and Cu—Ga alloy sputtering targets of Comparative Examples 1 to 4 were produced.
Comparative Example 1 is a hot press at a high temperature outside the temperature range in the sputtering target manufacturing method of the present invention, in which the Ga content in the raw material powder A is smaller than that in the example and the θ phase ratio is low. Comparative Example 2 is a case where the content of Ga in the raw material powder A is larger than that in the Example, and there is no γ phase. In Comparative Example 3, the raw material powder A and the raw material powder Although it is a case where B is used, it is a case where the mixing rate of the raw material powder B is high and the content of Ga in the CuGa raw material powder is smaller than in the case of the example. Moreover, although the comparative example 4 is a case where the raw material powder A and the raw material powder B are used, it is a case where the mixing ratio of the raw material powder A is high.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
 以上のように作製した実施例1~23及び比較例1、3のスパッタリングターゲットに関して、焼結体の密度と、Cu-Ga合金のγ相、θ相に係る平均結晶粒径と、θ相の割合と、表面粗さとを測定し、ターゲット組織と、切削時チッピングの発生とを観察し、ターゲット加工性について調べた。なお、比較例2の場合には、加工時にGaが溶出し、割れが発生したため、そして、比較例4の場合には、焼結時にθ相の溶け出しがあり、成型できなかったため、各種の評価を実施しなかった。 Regarding the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3 manufactured as described above, the density of the sintered body, the average crystal grain size related to the γ phase and θ phase of the Cu—Ga alloy, and the θ phase The ratio and the surface roughness were measured, the target structure and the occurrence of chipping during cutting were observed, and the target processability was examined. In the case of Comparative Example 2, Ga was eluted at the time of processing and cracking occurred, and in the case of Comparative Example 4, since the θ phase was melted during sintering and could not be molded, various types were obtained. Evaluation was not performed.
<焼結体密度の測定>
 上記実施例1~23及び比較例1、3のスパッタリングターゲットについて、焼結体の密度を測定した。各焼結体の寸法から算出した体積と重量とを用いて寸法密度(g/cm)を計算して求めた。
 この測定結果を、表4の「密度(g/cm)」欄に示した。
<Measurement of sintered body density>
For the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the density of the sintered body was measured. The dimensional density (g / cm 3 ) was calculated using the volume and weight calculated from the dimensions of each sintered body.
The measurement results are shown in the “Density (g / cm 3 )” column of Table 4.
<γ、θ相平均結晶粒径の測定>
 上記実施例1~23及び比較例1、3のスパッタリングターゲットについて、Cu-Ga合金のγ相及びθ相に係る平均結晶粒径について測定した。
 この測定にあたっては、スパッタリングターゲットから切り出した試料面を鏡面に研磨し、硝酸と純水とからなるエッチング液にてエッチングした後、EPMAにて結晶粒界を判別することができる倍率:50~1000倍の範囲内の組成像(COMPO像)を5枚撮る。市販の画像解析ソフト例えば、WinRoof(三谷商事社製)等により、撮影した画像をモノクロ画像に変換すると共に、しきい値を使用して二値化する。これによりγ相(或いは、θ相)を黒く表示させ得られた画像のγ相(或いは、θ相)のうち任意に選択した20個の結晶に対して最大外接円を描き、この直径の平均をこの画像での平均結晶粒径とし、さらに5枚の画像の平均値を平均結晶粒径とする。
 この測定結果を、表4の「γ相平均結晶粒径(μm)」欄及び「θ相平均結晶粒径(μm)」欄に示した。
<Measurement of average grain size of γ and θ phases>
For the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the average crystal grain size related to the γ phase and the θ phase of the Cu—Ga alloy was measured.
In this measurement, the sample surface cut out from the sputtering target is polished to a mirror surface, etched with an etching solution composed of nitric acid and pure water, and then the grain boundary can be determined by EPMA: 50 to 1000 Five composition images (COMPO images) within the double range are taken. A commercially available image analysis software such as WinRoof (manufactured by Mitani Corporation) or the like converts the captured image into a monochrome image and binarizes it using a threshold value. As a result, the maximum circumscribed circle is drawn for 20 crystals selected arbitrarily from the γ phase (or θ phase) of the image obtained by displaying the γ phase (or θ phase) in black, and the average of the diameters is drawn. Is the average crystal grain size in this image, and the average value of the five images is the average crystal grain size.
The measurement results are shown in the “γ phase average crystal grain size (μm)” column and “θ phase average crystal grain size (μm)” column of Table 4.
<θ相の割合>
 上記実施例1~23及び比較例1、3のスパッタリングターゲットについて、X線回折(XRD)パターンで得られた前記θ相に帰属する回折ピークの主ピーク強度と、前記γ相に帰属する回折ピークの主ピーク強度とを測定し、γ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比を算出して、θ相の割合を求めた。なお、回折ピークの主ピーク強度は、θ相では(102)面を、γ相では(330)面のピーク強度とした。
 このXRDパターンは、スパッタリングターゲットのスパッタ面をSiC-Paper(grit 180)にて湿式研磨、乾燥の後、測定した。この分析に使用した装置及び測定条件を以下に示す。
 装置:理学電気社製(RINT-Ultima/PC)
 管球:Cu
 管電圧:40kV
 管電流:40mA
 走査範囲(2θ):20゜~120°
 スリットサイズ:発散(DS)2/3度、散乱(SS)2/3度、受光(RS)0.8mm
 測定ステップ幅:2θで0.02度
 スキャンスピード:毎分2度
 試料台回転スピード:30rpm
 以上の条件で取得した回折ピークグラフ(例えば、図2)におけるγ相の(102)面の強度とθ相の(330)面強度とから、θ相の割合を求めた。即ち、強度比からθ相の割合を、下記の計算式で求めた。
 θ相の割合=Iobs(θ相)/Iobs(γ相)
 ここで、Iobs(θ相)は、θ相(201)面の測定強度、Iobs(γ相)は、γ相(330)面の測定強度である。
 以上の測定結果を、表4の「θ相割合」欄に示した。
<Ratio of θ phase>
For the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the main peak intensity of the diffraction peak attributed to the θ phase obtained by the X-ray diffraction (XRD) pattern and the diffraction peak attributed to the γ phase The ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase was calculated to determine the ratio of the θ phase. The main peak intensity of the diffraction peak was the (102) plane in the θ phase and the (330) plane peak intensity in the γ phase.
This XRD pattern was measured after wet-polishing and drying the sputtering surface of the sputtering target with SiC-Paper (grit 180). The apparatus and measurement conditions used for this analysis are shown below.
Equipment: Rigaku Electric Co., Ltd. (RINT-Ultima / PC)
Tube: Cu
Tube voltage: 40 kV
Tube current: 40 mA
Scanning range (2θ): 20 ° ~ 120 °
Slit size: Divergence (DS) 2/3 degrees, Scattering (SS) 2/3 degrees, Light reception (RS) 0.8mm
Measurement step width: 0.02 degrees at 2θ Scan speed: 2 degrees per minute Sample stage rotation speed: 30 rpm
The ratio of the θ phase was determined from the intensity of the (102) plane of the γ phase and the (330) plane intensity of the θ phase in the diffraction peak graph (for example, FIG. 2) obtained under the above conditions. That is, the ratio of the θ phase was determined from the intensity ratio by the following calculation formula.
Ratio of θ phase = I obs (θ phase) / I obs (γ phase)
Here, I obs (θ phase) is the measured intensity of the θ phase (201) plane, and I obs (γ phase) is the measured intensity of the γ phase (330) plane.
The above measurement results are shown in the “θ phase ratio” column of Table 4.
<ターゲット組織の観察>
 上記実施例1~23及び比較例1、3のスパッタリングターゲットについて、EPMAによって得られた組成像(COMPO像)の写真から、γ相中にθ相が分散した組織を「A」、γ相単一相を「B」として表4の「ターゲット組織」欄に示した。
<Observation of target tissue>
From the photographs of composition images (COMPO images) obtained by EPMA for the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the structure in which the θ phase is dispersed in the γ phase is indicated as “A”, One phase is shown as “B” in the “Target organization” column of Table 4.
<ターゲット加工性の評価>
 上記実施例1~23及び比較例1、3のスパッタリングターゲットの加工性の評価として、切削時のチッピング発生と、ターゲット表面の粗さとについて測定した。
(切削時チッピング発生の測定)
 作製されたスパッタリングターゲットを旋盤加工し、その後に、チッピング(割れ又は欠損)の有無を測定し、さらに、加工後のターゲット表面の粗さ(Ra:算術平均粗さ)を測定した。旋盤加工の条件としては、回転数100rpm、切り込み量0.7mm、送り0.097mm/revとした。インサートには、市販の超硬材料のものを用いた。
 この測定結果を、表4の「切削時チッピング」欄に示した。表4の同欄では、最大チッピングサイズが0.3mm以下の場合を、「S(Smallの略)」、最大チッピングサイズが0.3mm超え0.5mm以下の場合を、「M(Mediumの略)」、最大チッピングサイズ0.5mm超えの場合を、「L(Largeの略)」と表記し、0.5mm以下を加工性良好とした。
<Evaluation of target processability>
As an evaluation of the workability of the sputtering targets of Examples 1 to 23 and Comparative Examples 1 and 3, the occurrence of chipping during cutting and the roughness of the target surface were measured.
(Measurement of chipping during cutting)
The produced sputtering target was turned, and then the presence or absence of chipping (cracking or chipping) was measured, and the roughness (Ra: arithmetic average roughness) of the target surface after processing was further measured. As lathe processing conditions, the rotation speed was 100 rpm, the cutting depth was 0.7 mm, and the feed was 0.097 mm / rev. A commercially available super hard material was used for the insert.
The measurement results are shown in the “chipping during cutting” column of Table 4. In the same column of Table 4, when the maximum chipping size is 0.3 mm or less, “S (abbreviation for Small)”, and when the maximum chipping size is more than 0.3 mm and 0.5 mm or less, “M (abbreviation for Medium) ) ”, When the maximum chipping size exceeds 0.5 mm, it was expressed as“ L (abbreviation for Large) ”, and 0.5 mm or less was considered as good workability.
 (表面粗さRaの測定)
 作製されたスパッタリングターゲットを旋盤加工し、加工後のターゲット表面の粗さ(Ra:算術平均粗さ)を表面粗さ測定器(Mitsutoyo社製Surf Test SV-3000H4)にて測定した。この測定では、触針先端曲率半径2μm、触針先端角度60゜の針を用い、JIS B 0651:2001に従い、加工跡の線に対して垂直に交わる線分にて測定を行った。
 この測定結果を、表4の「表面粗さRa(μm)」欄に示した。
(Measurement of surface roughness Ra)
The produced sputtering target was turned, and the roughness (Ra: arithmetic average roughness) of the processed target surface was measured with a surface roughness measuring instrument (Surf Test SV-3000H4 manufactured by Mitsutoyo). In this measurement, a needle having a radius of curvature of the stylus tip of 2 μm and a stylus tip angle of 60 ° was used, and measurement was performed on a line segment perpendicular to the line of the processing trace according to JIS B 0651: 2001.
The measurement results are shown in the “Surface roughness Ra (μm)” column of Table 4.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
 表4の結果によれば、本願発明の実施例1~23は、いずれもγ相の平均粒径が50.0μm以下と小さく、X線回折においては、γ相とθ相との2相が観察され、上記θ相の割合が、10.0以下であることが確認できた。また、これら実施例では、切削時チッピングに関して、良好な結果が得られ、加工性の向上が確認された。 According to the results in Table 4, in Examples 1 to 23 of the present invention, the average particle diameter of the γ phase is as small as 50.0 μm or less. In X-ray diffraction, two phases of the γ phase and the θ phase are present. Observed, it was confirmed that the ratio of the θ phase was 10.0 or less. In these examples, good results were obtained with respect to chipping during cutting, and improvement in workability was confirmed.
 これらに対して、比較例1では、原料粉Aを原料粉末とした場合であるが、Ga成分が少なく、本願発明のスパッタリングターゲットの製造方法の温度範囲を外れた高い温度でホットプレスしたため、θ相が生成されず、ターゲット組織がγ相単一相となり、切削時にチッピングが発生した。また、比較例2では、Gaが、本願発明のスパッタリングターゲットおよびスパッタリングターゲットの製造方法の組成範囲から外れて多すぎるため、加工時に、Gaが溶出し、ターゲットの割れが発生した。比較例3では、γ相の単一相からなる原料粉Bの混合割合が大きいため、θ相からなる原料粉Aを用いたとしても、θ相が生成されず、ターゲット組織がγ相単一相となり、切削時にチッピングが発生した。比較例4では、焼結時にθ相の溶け出しがあり、成型できなかったため、スパッタリングターゲットを作製できなかった。この様に、比較例のいずれも、加工性が劣るものであった。 On the other hand, in Comparative Example 1, although the raw material powder A was used as the raw material powder, the Ga component was small and hot pressing was performed at a high temperature outside the temperature range of the sputtering target manufacturing method of the present invention. No phase was generated, the target structure became a single γ phase, and chipping occurred during cutting. In Comparative Example 2, Ga was too much out of the composition range of the sputtering target and the sputtering target manufacturing method of the present invention, so that Ga was eluted during processing, and the target was cracked. In Comparative Example 3, since the mixing ratio of the raw material powder B composed of a single phase of γ phase is large, even if the raw material powder A composed of the θ phase is used, the θ phase is not generated, and the target structure is a single γ phase. Phase and chipping occurred during cutting. In Comparative Example 4, the sputtering of the sputtering target could not be performed because the θ phase melted during sintering and could not be molded. Thus, all of the comparative examples were inferior in workability.
 以上の結果からわかるように、本願発明のスパッタリングターゲットにおいては、Gaの含有量が30.0~67.0原子%の範囲であって、温度:150~400℃で焼結されると、Cu-Ga合金のγ相に帰属する回折ピークとθ相に帰属する回折ピークとが両方観察され、γ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比(θ相の割合)が、0.01~10.0の範囲内にあることが確認された。例えば、図3に示されたEPMA画像の写真や、図2に示されたXRD回折結果のグラフからも、γ相のマトリックス中に、相対的にGaが多く含有されているθ相が分散した結晶組織を有していることを確認できた。
 従って、本願発明のスパッタリングターゲットについて、Cu-Ga合金の焼結体におけるγ相マトリックス中に、θ相を分散させることにより、加工時のチッピング(割れ、欠け)の発生を抑制できることが分かった。
As can be seen from the above results, in the sputtering target of the present invention, when the Ga content is in the range of 30.0 to 67.0 atomic% and sintered at a temperature of 150 to 400 ° C., Cu -Both the diffraction peak attributed to the γ phase and the diffraction peak attributed to the θ phase of the Ga alloy are observed, and the ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase It was confirmed that the (ratio of the θ phase) was in the range of 0.01 to 10.0. For example, from the photograph of the EPMA image shown in FIG. 3 and the graph of the XRD diffraction results shown in FIG. 2, the θ phase containing a relatively large amount of Ga is dispersed in the matrix of γ phase. It was confirmed that it had a crystal structure.
Accordingly, it has been found that the occurrence of chipping (cracking, chipping) during processing can be suppressed by dispersing the θ phase in the γ phase matrix in the sintered body of the Cu—Ga alloy in the sputtering target of the present invention.
 なお、本願発明のスパッタリングターゲットは、面粗さ:1.5μm以下、電気抵抗:1×10-4Ω・cm以下、金属系不純物濃度:0.1原子%以下、抗折強度:150MPa以上であることが好ましい。上記各実施例は、いずれもこれらの条件を満たしたものである。
 また、本願発明の技術範囲は上記実施形態および上記実施例に限定されるものではなく、本願発明の趣旨を逸脱しない範囲において種々の変更を加えることが可能である。
 例えば、上記実施形態及び上記実施例のスパッタリングターゲットは、平板状のものであるが、円筒状のスパッタリングターゲットとしても構わない。
The sputtering target of the present invention has a surface roughness of 1.5 μm or less, an electric resistance of 1 × 10 −4 Ω · cm or less, a metal impurity concentration of 0.1 atomic% or less, and a bending strength of 150 MPa or more. Preferably there is. Each of the above-described embodiments satisfies these conditions.
The technical scope of the present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the spirit of the present invention.
For example, although the sputtering target of the said embodiment and the said Example is a flat thing, it is good also as a cylindrical sputtering target.
 加工性の高いCIGS薄膜形成用スパッタリングターゲットを提供することができるようになり、高性能太陽電池の生産の効率化に役立つ。 It becomes possible to provide a sputtering target for forming a CIGS thin film with high workability, which helps to increase the efficiency of production of high-performance solar cells.
 A  θ相
 B  γ相
A θ phase B γ phase

Claims (8)

  1.  30.0~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成を有し、
     Cu-Ga合金のγ相マトリックス中に、Cu-Ga合金のθ相が分散している組織を備えた焼結体からなることを特徴とするスパッタリングターゲット。
    Containing 30.0 to 67.0 atomic% of Ga, with the balance being composed of Cu and inevitable impurities,
    A sputtering target comprising a sintered body having a structure in which a θ phase of a Cu—Ga alloy is dispersed in a γ phase matrix of a Cu—Ga alloy.
  2.  前記γ相の平均結晶粒径が、5.0~50.0μmであることを特徴とする請求項1に記載のスパッタリングターゲット。 The sputtering target according to claim 1, wherein an average crystal grain size of the γ phase is 5.0 to 50.0 µm.
  3.  前記θ相の平均結晶粒径が、5.0~100.0μmであることを特徴とする請求項1に記載のスパッタリングターゲット。 2. The sputtering target according to claim 1, wherein an average crystal grain size of the θ phase is 5.0 to 100.0 μm.
  4.  スパッタ面のX線回折パターンで得られた前記γ相に帰属する回折ピークの主ピーク強度に対する前記θ相に帰属する回折ピークの主ピーク強度の比が、0.01~10.0であることを特徴とする請求項1乃至3のいずれか一項に記載のスパッタリングターゲット。 The ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the main peak intensity of the diffraction peak attributed to the γ phase obtained from the X-ray diffraction pattern of the sputter surface is 0.01 to 10.0. The sputtering target according to any one of claims 1 to 3, wherein:
  5.  さらに、Naを0.05~15原子%の範囲内で含有することを特徴とする請求項1乃至4のいずれか一項に記載のスパッタリングターゲット。 5. The sputtering target according to claim 1, further comprising Na in a range of 0.05 to 15 atomic%.
  6.  前記Naは、フッ化ナトリウム、硫化ナトリウム、セレン化ナトリウムのうち少なくとも1種のNa化合物の状態で含有されていることを特徴とする請求項5に記載のスパッタリングターゲット。 The sputtering target according to claim 5, wherein the Na is contained in a state of at least one Na compound among sodium fluoride, sodium sulfide, and sodium selenide.
  7.  40.0~67.0原子%のGaを含有し、残部がCu及び不可避不純物からなるCu-Ga合金粉末であって、X線回パターンで得られたγ相に帰属する回折ピークの主ピーク強度に対するθ相に帰属する回折ピークの主ピーク強度の比が、0.01~10.0である粉末を、非酸化雰囲気若しくは還元性雰囲気中で、前記主ピーク強度の比が0.5以下の場合には、焼成温度を254℃以上450℃以下で、主ピーク強度の比が0.5より大きい場合には、焼成温度を254℃未満で焼結して焼結体を作製する工程を有していることを特徴とするスパッタリングターゲットの製造方法。 The main peak of the diffraction peak attributed to the γ phase obtained by the X-ray diffraction pattern, which is a Cu—Ga alloy powder containing 40.0 to 67.0 atomic% of Ga, the balance being Cu and inevitable impurities The ratio of the main peak intensity of the diffraction peak attributed to the θ phase to the intensity is 0.01 to 10.0 in a non-oxidizing atmosphere or a reducing atmosphere, and the ratio of the main peak intensity is 0.5 or less. In this case, when the firing temperature is 254 ° C. or more and 450 ° C. or less and the ratio of the main peak intensity is larger than 0.5, the step of sintering at a firing temperature of less than 254 ° C. to produce a sintered body is performed. A method for producing a sputtering target, comprising:
  8.  組成式がCu1-xGa、但しx=0.295~0.426で表されるCu-Ga合金のγ相からなる原料粉と、組成式がCu1-xGa、但し、x=0.646~0.667で表されるCu-Ga合金のθ相からなる原料粉を、θ相からなる原料粉の混合比率を35%以下で、かつ、30.0~42.6原子%のGaを含有し、残部がCu及び不可避不純物からなる成分組成となるように混合した混合粉末を、非酸化雰囲気若しくは還元性雰囲気中で、温度:150~400℃で焼結して焼結体を作製する工程を有していることを特徴とするスパッタリングターゲットの製造方法。 A raw material powder composed of a γ phase of a Cu—Ga alloy represented by a composition formula of Cu 1−x Ga x , where x = 0.295 to 0.426, and a composition formula of Cu 1−x Ga x , where x = The raw material powder composed of the θ phase of the Cu-Ga alloy represented by 0.646 to 0.667, the mixing ratio of the raw material powder composed of the θ phase is 35% or less, and 30.0 to 42.6 atoms Sintered by sintering a mixed powder containing 1% Ga and mixed so that the balance is composed of Cu and inevitable impurities in a non-oxidizing or reducing atmosphere at a temperature of 150 to 400 ° C. A method for producing a sputtering target, comprising a step of producing a body.
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JP2011149039A (en) * 2010-01-20 2011-08-04 Sanyo Special Steel Co Ltd Cu-Ga-BASED SPUTTERING TARGET MATERIAL HAVING HIGH STRENGTH, AND METHOD FOR MANUFACTURING THE SAME
WO2012098722A1 (en) * 2011-01-17 2012-07-26 Jx日鉱日石金属株式会社 Cu-ga target and method for manufacturing same, as well as light-absorbing layer formed from cu-ga alloy film, and cigs solar cell using light-absorbing layer

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JP2008138232A (en) * 2006-11-30 2008-06-19 Mitsubishi Materials Corp HIGH Ga CONTENT Cu-Ga BINARY ALLOY SPUTTERING TARGET, AND ITS MANUFACTURING METHOD
WO2011055537A1 (en) * 2009-11-06 2011-05-12 三菱マテリアル株式会社 Sputtering target and process for production thereof
JP2011149039A (en) * 2010-01-20 2011-08-04 Sanyo Special Steel Co Ltd Cu-Ga-BASED SPUTTERING TARGET MATERIAL HAVING HIGH STRENGTH, AND METHOD FOR MANUFACTURING THE SAME
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