Sputtering target, method for producing same, and film

Abstract

Provided are: a sputtering target configured to suppress trouble that could occur at the time of sputtering; and a method for manufacturing the same. The sputtering target contains a binary alloy of Cu and Al, with the balance being unavoidable impurities. The content (at%) of Cu and Al satisfies the condition of: 0.48 ≤ Al / (Cu + Al) ≤ 0.70; and further satisfies at least one of conditions (1)-(3). Condition (1): 0.48 ≤ Al / (Cu + Al) < 0.55, and the area ratio of pores in the field of view when observed by SEM being 2.0% or less. Condition (2): 0.55 ≤ Al / (Cu + Al) ≤ 0.70, and the area ratio of pores in the field of view when observed by SEM being 1.0% or less. Condition (3): the oxygen content of the sputtering target is 1000 ppm by mass or less, and the bending strength of the sputtering target is 70 MPa or more.

Description

Sputtering target, its manufacturing method and film

[0001] The present disclosure relates to a sputtering target (hereinafter sometimes simply referred to as a "target"), a method for producing the same, and a film.

[0002] Some semiconductor devices have a multilayer wiring structure, which includes conductor wiring, an insulating film, a diffusion barrier layer, etc. Conventionally, pure Cu has often been used for conductor wiring, but in recent years, new problems such as electrical resistance have emerged as wiring becomes finer. Accordingly, new materials for conductor wiring are being sought.

[0003] Patent Document 1 discloses a Cu-Al binary alloy sputtering target with a high Al content that can suppress cracking of the sputtering target, and a method for manufacturing the same. Specifically, Patent Document 1 discloses the following sputtering target: a sputtering target constituted by a sintered body containing a binary alloy of Cu and Al, with the balance being unavoidable impurities, in which the contents (at %) of Cu and Al satisfy the relational expression 0.48≦Al / (Cu+Al)≦0.70, and the sputtering target has a relative density of 95% or more.

[0004] Japanese Patent Application Laid-Open No. 2023-124653

[0005] Patent Document 1 discloses a Cu-Al binary alloy sputtering target with a high Al content that is provided for the purpose of suppressing cracking during sputtering. However, the sputtering target disclosed in Patent Document 1 leaves room for further improvement from the perspective of suppressing problems during sputtering. Therefore, an object of the present disclosure is to provide a sputtering target that suppresses problems during sputtering, and a method for manufacturing the same.

[0006] To achieve the above object, one aspect of the present disclosure includes the following inventions: (Invention 1) A sputtering target containing a binary alloy of Cu and Al, with the balance being unavoidable impurities, wherein the contents (at %) of Cu and Al satisfy the following conditions: 0.48≦Al / (Cu+Al)≦0.70 (1) When 0.48≦Al / (Cu+Al)<0.55, the area ratio of pores within the field of view when observed with an SEM is 2.0% or less, and (2) When 0.55≦Al / (Cu+Al)≦0.70, the area ratio of pores within the field of view when observed with an SEM is 1.0% or less. (Invention 2) The sputtering target of Invention 1, wherein the Cu and Al contents (at %) satisfy the following conditions: 0.48≦Al / (Cu+Al)≦0.52, and the pore area ratio within the field of view when observed with an SEM is 2.0% or less. (Invention 3) The sputtering target of Invention 1, wherein the Cu and Al contents (at %) satisfy the following conditions: 0.65≦Al / (Cu+Al)≦0.69, and the pore area ratio within the field of view when observed with an SEM is 1.0% or less. (Invention 4) The sputtering target of any one of Inventions 1 to 3, having a flexural strength of 70 MPa or more. (Invention 5) The sputtering target of any one of Inventions 1 to 4, wherein the sputtering target has an oxygen content of 1000 ppm by mass or less. (Invention 6) A sputtering target containing a binary alloy of Cu and Al, with the balance being unavoidable impurities, wherein the Cu and Al contents (at %) satisfy the following conditions: 0.48≦Al / (Cu+Al)≦0.70, the oxygen content of the sputtering target is 1000 mass ppm or less, and the flexural strength is 70 MPa or more. (Invention 7) The sputtering target of Invention 6, wherein the Cu and Al contents (at %) satisfy the following conditions:0.65≦Al / (Cu+Al) ≦0.69 (Invention 8) The sputtering target of Invention 6, wherein the contents (at %) of Cu and Al satisfy the following conditions: 0.48≦Al / (Cu+Al) ≦0.52 The sputtering target has a flexural strength of 100 MPa or more. (Invention 9) A method for producing the sputtering target according to any one of Inventions 1 to 8, the method comprising: a step of providing an ingot; a step of producing powder from the ingot by a disk atomization method; and a step of producing a sintered body from the powder by hot pressing, and satisfies one or more of the following conditions: the step of producing powder comprises adjusting the particle size distribution to satisfy the following conditions: D50V 40.0 to 50.0 μm D90V 65.0 to 100.0 μm; the step of producing a sintered body comprises hot pressing under the following conditions: Temperature: 500 to 700°C Pressure: 200 to 450 kgf / cm. 2 Holding time: 9 hours or more. (Invention 10) A method for producing a sputtering target of Invention 9, wherein the step of producing a powder comprises adjusting the particle size distribution to satisfy the following condition: ((D90V - D10V) / D10V) >= 1.90. (Invention 11) A method for producing a sputtering target of Invention 9 or 10, wherein the step of producing a powder comprises adjusting the particle size distribution to satisfy the following condition: ((D90V - D10V) / D50V) >= 1.12. (Invention 12) A film produced using the sputtering target according to any one of Inventions 1 to 8.

[0007] In one aspect of the above invention, the pore area ratio within the field of view observed with an SEM satisfies the following conditions: (1) when 0.48≦Al / (Cu+Al)<0.55, the pore area ratio within the field of view observed with an SEM is 2.0% or less; and (2) when 0.55≦Al / (Cu+Al)≦0.70, the pore area ratio within the field of view observed with an SEM is 1.0% or less. This provides a sputtering target with high Vickers hardness. Furthermore, the high Vickers hardness can suppress cracking.

[0008] In one aspect of the above invention, the target has a bending strength of 70 MPa or more and an oxygen content of 1000 mass ppm or less. A bending strength of 70 MPa or more can suppress warping during sputtering. As a result, problems caused by warping during sputtering (e.g., arcing) can be reduced. Furthermore, a low oxygen content can reduce other problems during sputtering (e.g., particles).

[0009] 1 is a diagram showing measurement points of a sputtering target for evaluating composition uniformity, FIG. 2 is a diagram showing a setting screen of image analysis software, FIG. 3 is a diagram showing SEM images of Test Example 1, and FIG. 4 is a diagram showing SEM images of Test Example 3.

[0010] Specific embodiments for carrying out the present invention will be described below. The following description is intended to facilitate understanding of the invention and is not intended to limit the scope of the present invention.

[0011] 1. Composition In one embodiment, the present disclosure relates to a sputtering target comprising a binary alloy of Cu and Al, with the balance consisting of unavoidable impurities. The sputtering target may include a backing plate and, in addition, may include a bonding layer.

[0012] The shape of the sputtering target is not particularly limited, but it may typically be a flat plate (for example, circular, rectangular, etc.).

[0013] In the sputtering target, the contents (at %) of Cu and Al satisfy the relational expression 0.48≦Al / (Cu+Al)≦0.70.

[0014] By setting the Al content to 48 at% or more and 70 at% or less relative to the total content of Cu and Al, a conductor made of an intermetallic compound of Cu and Al can be formed satisfactorily. This conductor can be expected to have properties such as excellent conductivity and adhesion between the conductor and the insulator. From this perspective, the Al content relative to the total content of Cu and Al is preferably 50 at% or more, more preferably 55 at% or more, even more preferably 62 at% or more, and even more preferably 66 at% or more.

[0015] From the same viewpoint, the content of Al relative to the total content of Cu and Al is preferably 69 at% or less, and more preferably 68 at% or less. From another viewpoint (for example, from the viewpoint of the type of alloy of Cu and Al), the content of Al relative to the total content of Cu and Al is preferably less than 55 at%.

[0016] Preferably, the sputtering target comprises a CuAl2 and / or CuAl intermetallic compound, and even more preferably, the sputtering target consists of a CuAl2 and / or CuAl intermetallic compound, i.e., the Cu and Al contents are preferably Al / (Cu+Al)=0.67±0.02 or Al / (Cu+Al)=0.50±0.02, even more preferably Al / (Cu+Al)=0.67±0.01 or Al / (Cu+Al)=0.50±0.01, and even more preferably Al / (Cu+Al)=0.67 or Al / (Cu+Al)=0.50.

[0017] If a target material of CuAl or a CuAl intermetallic compound can be produced, there is no need to separately produce pure metal targets of Cu and Al for forming a CuAl wiring material or a CuAl wiring material, and there is less risk of impurities being mixed in during sputtering. Therefore, the purity of the sputtering target in one embodiment is preferably 4N (99.99% by mass) or higher, more preferably 4N5 (99.995% by mass) or higher, and even more preferably 5N (99.999% by mass) or higher.

[0018] Here, the purity of the sputtering target being 4N (99.99% by mass) or higher means that, when a composition analysis is performed by glow discharge mass spectrometry (GDMS), the total amount of Na, P, S, K, Ca, Cr, Fe, Ni, As, Ag, Sb, Bi, Th, and U contained in the sputtering target is less than 0.01% by mass (100 ppm by mass).

[0019] When a sputtering target is produced from an ingot made of an intermetallic compound of Cu and Al as described below, the contents of Cu and Al can be the contents of Cu and Al in the ingot. When measuring from a sputtering target of a product, the composition of the sputtering target can be measured by inductively coupled plasma optical emission spectroscopy (ICP-OES).

[0020] (2. Relative Density) The relative density is not particularly limited, but in a preferred embodiment, the relative density of the sputtering target of the present disclosure may be 95.0% or more. A higher relative density of the target is preferable for stable sputtering with less arcing. The relative density is preferably 97% or more, more preferably 98.0% or more, and even more preferably 99.0% or more. There is no particular upper limit to the relative density, but it can be, for example, 100% or less, or 99.9% or less, or 99.5% or less, or 99.0% or less.

[0021] The relative density is calculated by the formula: relative density = measured density ÷ theoretical density × 100 (%). Here, the measured density is the value obtained by dividing the weight by the volume, and the volume is measured by the Archimedes method. The theoretical density is calculated by assuming that the entire sputtering target is made of CuAl (θ phase) and CuAl (η phase), and the theoretical density of CuAl (θ phase) is 4.35 g / cm. 3 , the theoretical density of CuAl (η phase) is 5.36 g / cm 3 The relative density calculated using this theoretical density may exceed 100%.

[0022] (3. Uniformity of Composition) In one embodiment of the present disclosure, when the Al content at a total of five points on the sputtering surface of a flat sputtering target, which are aligned on two mutually perpendicular straight lines extending from the center to the periphery, including the central position, the peripheral position, and an intermediate position between them, is measured by ICP-OES, it is preferable that the difference between the maximum and minimum values ​​of each content be 0.2 at% or less. The peripheral position is defined as a position extending from the outermost periphery of the sputtering target toward the center, which is 1 / 8 of the length from the center to the outermost periphery. The intermediate position between the central position and the peripheral position is defined as a position at the center point of the line connecting the central position and the peripheral position. In this way, small differences in Al content at measurement points and high uniformity of composition make the composition of the sputtering target uniform at each point, which is useful for forming a uniform conductive layer.

[0023] From this viewpoint, it is more preferable that the difference between the maximum and minimum values ​​of the Al content measured by the above method is 0.1 at% or less. This uniformity of composition cannot be achieved, for example, with a sputtering target in which elemental Cu and elemental Al are alternately arranged or mixed, but a high level of uniformity can be achieved by producing atomized powder as described below.

[0024] Explaining with reference to Figure 1, when the sputtering surface of the sputtering target is circular, its center A is the center of the circle, and the five points of the center position A, peripheral positions E and C, and intermediate positions B and D between them are arranged in an L-shape. The peripheral positions E and C are located at 1 / 8 of the length from the center A to the center A of the outermost periphery of the sputtering target. When the sputtering surface of the sputtering target is rectangular, its center is the intersection of the diagonals. Furthermore, when the sputtering surface of the sputtering target is rectangular, the peripheral position is located at 1 / 8 of the length from the center (intersection of the diagonals) to the corner.

[0025] (4. Crystal Structure) The crystal structure of a sputtering target can be identified by analyzing the sputtering surface with an XRD (X-ray diffractometer). The mass ratio of each crystal phase can be obtained by quantitatively analyzing the results of the XRD analysis using the RIR (Reference Intensity Ratio) method. Here, the RIR method is a method for determining the mass ratio of the crystal phases from the ratio between the RIR value and the value of the strongest peak intensity of each crystal phase obtained from the XRD results. When the sputtering target contains crystal phases A, B, C, ..., the mass ratio X of the crystal phase A is A is calculated using the following formula: A =I A k A / (I A k A +I B k B +I C k C + ...) where I represents the intensity of the strongest X-ray peak of each crystalline phase, and k represents the RIR value of each crystalline phase. The RIR values ​​can be those listed in the Powder Diffraction File (PDF) database of the International Center for Diffraction Data (ICSD Nos. 01-071-5027 and 03-065-1228). Quantitative analysis using the RIR method can obtain quantitative values ​​for the Cu, Al, CuAl2, and CuAl phases, and therefore the mass ratio of the total value of CuAl2 + CuAl can also be obtained.

[0026] The mass ratio of the total value of CuAl2 + CuAl is preferably 95% or more, more preferably 98% or more. This allows for the satisfactory formation of a conductor consisting of an intermetallic compound of Cu and Al. Furthermore, when CuAl2 is the main phase, the mass ratio of CuAl2 is preferably 70% or more, more preferably 90% or more, and even more preferably 95% or more. Here, the main phase refers to the crystalline phase that is most abundant among the crystalline phases contained in the sputtering target. When CuAl is the main phase, the mass ratio of CuAl is preferably 70% or more, more preferably 90% or more, and even more preferably 95% or more. This allows for the satisfactory formation of a conductor consisting of an intermetallic compound of Cu and Al. Furthermore, in a preferred embodiment of the present disclosure, the mass ratio of the total value of CuAl2 + CuAl is 100%, i.e., no single Cu phase or single Al phase is present.

[0027] (5. Pore Area) In the structure of the sputtering target according to one embodiment of the present disclosure, the pore area ratio within the field of view when observed with an SEM is 2.0% or less, preferably 1.0% or less, more preferably 0.5% or less, and most preferably 0.1% or less. In another embodiment, the pore area ratio is 2.00% or less, preferably 1.00% or less, more preferably 0.50% or less, and most preferably 0.10% or less.

[0028] In one embodiment, the upper limit of the pore area may vary depending on the composition. In one example, when 0.48≦Al / (Cu+Al)<0.55, the pore area ratio is 2.0% or less (e.g., 2.00% or less). In another example, when 0.55≦Al / (Cu+Al)≦0.70, the pore area ratio is 1.0% or less (e.g., 1.00% or less). While the tendency of the pore area varies depending on the composition, in one embodiment, the sputtering target of the present disclosure makes it possible to achieve a pore area that is lower than the pore area conventionally achieved when compared with the same composition.

[0029] The lower limit is not particularly limited, but may be, for example, 0.01% or more. In one example, when 0.48≦Al / (Cu+Al)<0.55 (preferably, 0.48≦Al / (Cu+Al)≦0.52), the lower limit of the pore area ratio may be 1.00% or more, typically 1.50% or more. In another example, when 0.55≦Al / (Cu+Al)≦0.70 (preferably, 0.65≦Al / (Cu+Al)≦0.69), the lower limit of the pore area ratio may be 0.01% or more, typically 0.80% or more. Here, the measurement location is not particularly limited. For example, the measurement points may be on the outer periphery of the sputtering target (for example, if the sputtering target has a circular shape, a portion of the circumference (for example, a portion corresponding to C and E in FIG. 1 ), or if the sputtering target has a rectangular shape, a position that is 1 / 8 of the length from the center (intersection of the diagonals) to a corner). Furthermore, a plurality of measurement points may be used, and in this case, the pore area ratio may be an average value of the measurement points.

[0030] By making the pore area ratio 2.0% or less (or 1.0% or less, depending on the composition), the sputtering target has a Vickers hardness of at least a certain level. And, by having a Vickers hardness of at least a certain level, cracking can be suppressed.

[0031] The pore area ratio can be measured by the following method. A sample is cut out from the sputtering target (for example, at the outer periphery) (for example, the sample size may be 10 mm x 10 mm x thickness: 3 to 20 mm). Prior to observation, the observation surface of the sample (the surface parallel to the sputtering surface) is polished with sandpaper #2000. Thereafter, the observation surface of the sample is buffed using a compound (abrasive). Pores are detected from secondary electron images obtained when observing the structure with an SEM (accelerating voltage 15.0 kV, observation area 350 μm x 500 μm, magnification 250x). The detected pores are subjected to image processing to calculate the pore area. The total pore area is divided by the area of ​​the field of view in the SEM.

[0032] Here, when detecting pores, the contrast is adjusted to detect the pores. This is because, depending on the contrast, certain pores may be easier to see, while other certain pores may be harder to see. In one example, the pore area is detected using a Hitachi High-Technologies Corporation, Model SU3500 scanning electron microscope, with the contrast adjusted using the instrument's manual operation panel. Then, in practice, the conditions under which the area ratio is highest as a result of adjusting the contrast are found, and the pore area ratio under those conditions is calculated. Furthermore, when performing image processing, the image analysis software Nikon NIS-Elements D is used. In Nikon NIS-Elements D, pore detection is performed using an object count tool. At this time, the brightness is set using the threshold panel. In this software, the brightness setting is automatically assigned to a range of 0 to 255, but here, the upper limit brightness setting is set to 50 or less (see Figure 2). Then, using the measurement function built into this software, the area of ​​the detected objects (pores) is measured and the total area is calculated.

[0033] (6. Flexural Strength) In one embodiment, the flexural strength of the sputtering target of the present disclosure is 70 MPa or more, preferably 80 MPa or more, more preferably 100 MPa or more, and even more preferably 110 MPa or more. High flexural strength can suppress warping during sputtering, resulting in the advantage of reducing problems (e.g., arcing) during sputtering. The upper limit is not particularly limited, but may be, for example, 100 MPa or less, or 150 MPa or less. The tendency of flexural strength varies depending on the composition. However, in one embodiment related to a specific composition (e.g., when the Al content (at %) is higher than the Cu content, e.g., when 0.55≦Al / (Cu+Al)≦0.70), the sputtering target of the present disclosure can achieve a flexural strength higher than that conventionally achieved.

[0034] Here, the flexural strength can be measured in accordance with JIS R 1601. The JIS standard stipulates that the thickness of the sample is 3 mm. To process the target to this thickness, the same amount is ground from the front and back surfaces of the target. Then, a sample is cut out from any part to have a rectangular size of 4 x 40 mm. The specific conditions are as follows. (Measurement conditions for flexural strength) Test method: Three-point bending test Distance between supports: 30 mm Sample size: 3 x 4 x 40 mm Support curvature radius: 5 mm Head speed: 0.5 mm / min

[0035] Here, the measurement points for the bending strength are not particularly limited, and for example, the measurement points for the bending strength may be the same as the measurement points for the pore area described above.

[0036] (7. Vickers Hardness) In one embodiment, the Vickers hardness of the sputtering target of the present disclosure is 460.0 or more, preferably 470.0 or more, and more preferably 700.0 or more. A high Vickers hardness can suppress cracking of the sputtering target. The upper limit is not particularly limited, but may be, for example, 550.0 or less, or 800.0 or less. The tendency of Vickers hardness varies depending on the composition, but in one embodiment, the sputtering target of the present disclosure makes it possible to achieve a Vickers hardness higher than the Vickers hardness conventionally achieved when compared with the same composition.

[0037] The Vickers hardness refers to a value measured based on the Vickers hardness test specified in JIS Z2244 (2009). Specifically, the Vickers hardness measurement conditions are as follows: Test force: 2.0 N, Indenter approach speed: 60 μm / sec, Test force holding time: 10 sec, Test temperature: Room temperature

[0038] Here, the location where the Vickers hardness is measured is not particularly limited, and for example, the location where the Vickers hardness is measured may be the same as the location where the pore area is measured as described above.

[0039] (8. Oxygen Concentration) In one embodiment, the oxygen concentration of the sputtering target of the present disclosure is 1000 ppm by mass or less, preferably 850 ppm by mass or less, more preferably 300 ppm by mass or less, and most preferably 200 ppm by mass or less. Sputtering targets with low oxygen concentrations tend to have fewer impurities. Furthermore, fewer impurities can suppress adverse effects during sputtering (for example, the possibility of particles being generated during sputtering). The lower limit of the oxygen concentration is not particularly limited, but may be 100 ppm by mass or more, or 150 ppm by mass or more.

[0040] In the manufacturing method described below, the particle size distribution of the raw material powder may be adjusted, but as the particle size decreases, the surface area per volume increases. This may result in a reaction with more oxygen, which may increase the oxygen content of the sputtering target. However, the sputtering target of the present disclosure has the characteristic of suppressing the pore area while avoiding an increase in the oxygen concentration.

[0041] The oxygen content of the sputtering target can be measured by an inert gas fusion-infrared absorption method (for example, TCH600 manufactured by LECO Corporation). Furthermore, during measurement, the entire sputtering target may be analyzed, or a portion of the target may be sampled and analyzed. When a portion of the sputtering target is sampled and analyzed, samples may be sampled from multiple locations and an average value may be calculated. Here, the location at which the oxygen concentration is measured is not particularly limited. For example, the location at which the oxygen concentration is measured may be the same as the location at which the pore area is measured as described above.

[0042] (9. Manufacturing Method) The manufacturing method of the sputtering target of the present disclosure is not particularly limited, but the manufacturing method in one embodiment includes at least the following steps: - A step of providing an ingot - A step of manufacturing a powder from the ingot by a disk atomization method - A step of manufacturing a sintered body from the powder by hot pressing

[0043] The method may have any one or more of the following additional features:

[0044] The process of producing the powder includes adjusting the particle size distribution to meet the following conditions: D50V 40.0 to 50.0 μm D90V 65.0 to 100.0 μm

[0045] The process for producing a sintered body includes hot pressing under the following conditions: Temperature: 500 to 700°C Pressure: 200 to 450 kgf / cm 2 Retention time: 9 hours or more

[0046] Each step will be described in detail below.

[0047] (9-1. Step of Providing an Ingot) In some embodiments of the present disclosure, the provided ingot may be an ingot in which the contents (at %) of Cu and Al satisfy the relational expression 0.48≦Al / (Cu+Al)≦0.70. In another embodiment of the present disclosure, the provided ingot may be an ingot made of Cu and an ingot made of Al in amounts that satisfy the relational expression 0.48≦Al / (Cu+Al)≦0.70. From the viewpoint of uniformity, the former embodiment is preferred.

[0048] In the former embodiment, it is preferable to melt the desired Cu and Al or melt the desired Cu-Al alloy to prepare an ingot so that the Cu and Al contents (at%) satisfy the relational expression 0.48≦Al / (Cu+Al)≦0.70. In this case, the material to be melted can be selected according to the final target composition described above. For example, if the target composition is CuAl2, a CuAl2 alloy may be melted, or the material may be added and melted so that the atomic ratio of Cu to Al is 1:2. In another example, if the target composition is CuAl, a CuAl alloy may be melted, or the material may be added and melted so that the atomic ratio of Cu to Al is 1:1. By melting the material to prepare an ingot, the raw materials are stirred once, which promotes homogenization.

[0049] The melting temperature is not particularly limited, but is preferably 800 to 1000°C, more preferably 850 to 950°C.

[0050] The molten metal can be tapped into a mold to produce the desired ingot.

[0051] (9-2. Step of Producing Atomized Powder from Ingot) The obtained ingot can be subjected to atomization to obtain atomized powder. It is preferable to use the above-mentioned ingot as the raw material (i.e., an ingot whose Cu and Al contents (at%) satisfy the relational expression 0.48≦Al / (Cu+Al)≦0.70), but there are no particular limitations as long as atomized powder having the desired atomic ratio of Cu to Al can be produced. For example, if the provided ingot contains a binary alloy of Cu and Al, with the remainder consisting of unavoidable impurities (and has the same composition as the desired target), it may be directly introduced into an atomization device and melted to produce atomized powder. In another example, the provided ingot may be two types of ingots, one consisting of a Cu ingot and one consisting of an Al ingot. For example, if the target component is CuAl2, Cu and Al may be charged into an atomizing device and melted so that the atomic ratio is 1:2 to produce atomized powder. In another example, if the target component is CuAl, Cu and Al may be charged into an atomizing device and melted so that the atomic ratio is 1:1 to produce atomized powder. By producing a powder through atomization, it can be subjected to hot pressing in the subsequent process, making it possible to produce a target. Furthermore, producing atomized powder can promote the homogenization of the material.

[0052] The atomization process can be performed by disk atomization, water atomization, gas atomization, etc., but disk atomization is used for production. The conditions for disk atomization are not particularly limited. By producing the powder by disk atomization, the shape of the powder tends to be suitable for packing (for example, high sphericity). This increases the packing rate, and as a result, a sputtering target with a small pore area can be obtained.

[0053] (9-3. Treatment of Atomized Powder) After obtaining the atomized powder, it may be further pulverized or not pulverized. The latter is preferable because there is a possibility that the oxygen concentration may increase.

[0054] The particle size distribution of the obtained atomized powder is not particularly limited. For example, the particle size distribution may satisfy the following conditions: D50V: 40.0 to 80.0 μm (preferably, 40.0 to 70.0 μm) D90V: 65.0 to 125.0 μm (preferably, 67.0 to 120.0 μm)

[0055] In a preferred embodiment, the particle size of the obtained atomized powder may be adjusted. For example, the particle size may be adjusted to satisfy the following conditions: D50V: 40.0 to 50.0 μm (preferably, 40.0 to 45.0 μm) D90V: 65.0 to 100.0 μm (preferably, 67.0 to 72.0 μm)

[0056] Here, D50V is the median diameter (volume basis) in the particle size distribution, while D90V is the particle size that accounts for 90% (volume basis).

[0057] The above-mentioned particle size distribution and its related values ​​(for example, D50V, D90V, etc.) can be measured by a laser diffraction / scattering method (LD).

[0058] The method for adjusting the particle size is not particularly limited, but typically, a sieve with a specific mesh size may be used. The mesh size of the sieve is not particularly limited and may be, for example, 70 to 170 μm. Preferably, the mesh size of the sieve may be 130 to 170 μm, or 80 to 100 μm.

[0059] By adjusting the particle size, the gaps when the powder is packed become smaller, leading to a reduction in the pore area.

[0060] In yet another preferred embodiment, the particle size distribution after adjustment is broad. For example, it is preferable that the width of the peak expressed in a particle size distribution graph is broad. The breadth of the particle size distribution is expressed by any of the following: ((D90V-D10V) / D10V) (Equation 1) or ((D90V-D10V) / D50V) (Equation 2)

[0061] When the breadth of the particle size distribution is expressed by the above formula 1, the value is preferably 1.90 or more, more preferably 2.00 or more. The upper limit is not particularly limited, but is typically 2.50 or less.

[0062] When the breadth of the particle size distribution is expressed by the above formula 2, the value is preferably 1.12 or more, more preferably 1.13 or more. The upper limit is not particularly limited, but is typically 1.20 or less.

[0063] If the particles are fine, the packing density tends to increase. However, if the particle size distribution is too biased toward extremely fine particles, it becomes difficult to increase the packing density, and pores may occur. As described above, by providing a certain degree of breadth in the particle size distribution, the possibility of pores occurring can be reduced. Furthermore, the finer the particles, the higher the bending strength tends to be, but if the particles are too fine, the bending strength will decrease, and further, there will be the disadvantage that the oxygen content of the sintered body will increase. From this perspective, as described above, it is preferable to adjust the particle size to an appropriate range.

[0064] (9-4. Hot Pressing Step) The atomized powder or a powder obtained by pulverizing the atomized powder is placed in a hot press container and hot pressed to obtain a sintered body. The hot pressing conditions are at least 500°C or higher, and preferably 550°C or higher. Pressing at 500°C or higher improves processability (for example, the possibility of cracking during manufacturing can be reduced). Pressing at 500°C or higher also improves relative density. The upper limit of the temperature is not particularly limited, but is 700°C or lower, typically 600°C or lower. It is more preferably 560 to 580°C.

[0065] The pressure is not particularly limited, but is preferably 200 to 450 kgf / cm 2 is preferred, and 250 to 350 kgf / cm 2 More preferably, 325 kgf / cm 2The following is most preferable. The holding time is also not particularly limited, but is preferably 3 to 20 hours, and more preferably 9 to 11 hours. Setting the holding time within this more preferable range leads to a reduction in the pore area. Furthermore, setting the holding time within this more preferable range can reduce the oxygen content in the sintered body.

[0066] (9-5. Other Steps) After the sintered body is obtained by hot pressing, other processing steps may be carried out as appropriate. For example, hot isostatic pressing may be carried out to further improve the relative density. Furthermore, in order to finish the sintered body into the shape of a product for shipping, machining such as grinding and / or cutting may be carried out as appropriate. The sintered body may then be bonded to a backing plate to form a final product. The conditions for these other steps are not particularly limited, and conditions known in the art may be used as appropriate.

[0067] As mentioned above, the above manufacturing method does not necessarily include the rolling step and the forging step because the powder is sintered.

[0068] The sputtering target according to one embodiment of the present invention has excellent processability and is less likely to crack during processing (e.g., grinding, cutting, etc.) during manufacturing. Furthermore, since the relative density is relatively high, wetting with grinding oil, etc., can be avoided. Furthermore, since it is manufactured as a sintered body, there is no need to perform rolling and forging processes, and the possibility of cracking due to these processes can be eliminated.

[0069] Furthermore, the sputtering target according to one embodiment of the present invention has excellent material uniformity, and exhibits little unevenness in appearance (e.g., color unevenness). For example, when observing the structure using a means such as an SEM, there is little difference in shading depending on the observation location.

[0070] (10. Applications) The sputtering target described above can be used for the purpose of forming a thin film by sputtering. Accordingly, in one embodiment, the present disclosure relates to a film containing a binary alloy of Al and Cu or a film made of the binary alloy, which is produced using the sputtering target described above, and a method for producing the same. Preferably, in one embodiment, the present disclosure relates to a semiconductor having a film of a binary alloy of Al and Cu, which is produced using the sputtering target described above, and a method for producing the same.

[0071] For example, the manufacturing method may include steps of placing a substrate and a sputtering target in a chamber so that they face each other, introducing an inert gas (e.g., Ar), and applying a voltage to form a thin film.

[0072] The present invention will be specifically described below with reference to examples, but the description here is for the purpose of illustration only and is not intended to be limiting.

[0073] Test Example 1 An ingot was prepared by melting (900° C.) a CuAl intermetallic compound having a composition of 66.7 at %±0.5 at % Al, with the remainder being Cu and unavoidable impurities. Next, the ingot was subjected to an atomization process (disk atomization).

[0074] The atomized powder was passed through a sieve with a mesh size of 150 μm, and the atomized powder that passed through the sieve was collected. The particle size of the collected atomized powder was measured by the method described above.

[0075] Furthermore, the collected atomized powder was subjected to hot pressing under the following conditions.

[0076] Temperature: 570℃ Surface pressure: 350kgf / cm 2 Holding time: 5 hours

[0077] The obtained sintered body (the shape of the sintered body is disk-like) was machined to obtain the center part of the sintered body as a target. The remaining part other than the target was obtained as scrap material. The Vickers hardness, flexural strength, pore area ratio, and oxygen content of the scrap material were then measured using the methods described above. Note that the distance between the scrap material and the outer periphery of the target after machining is only a few centimeters. Therefore, when measurements are made using a target instead of scrap material, the measurement points may be as follows: Vickers hardness: 2 outer periphery positions; flexural strength: 5 outer periphery positions; Pore area ratio: 1 outer periphery position; Oxygen content: 1 outer periphery position

[0078] (Test Example 2) A test was carried out under the same conditions as in Test Example 1. However, two conditions relating to the hot press were changed as follows: Surface pressure: 300 kgf / cm 2 Holding time: 10 hours

[0079] (Test Example 3) A test was carried out under the same conditions as in Test Example 1. However, one condition related to the hot pressing was changed as follows: surface pressure: 300 kgf / cm 2

[0080] Furthermore, in Test Example 3, the recovered atomized powder was sieved through a sieve with a mesh size of 90 μm, and the atomized powder that passed through the sieve was recovered. Then, the recovered atomized powder was subjected to hot pressing.

[0081] Test Example 4 A test was carried out under the same conditions as Test Example 3. However, after passing the atomized powder through a sieve with a mesh size of 90 μm, the recovered atomized powder was passed through a sieve with a mesh size of 63 μm, and the atomized powder that passed through the sieve was recovered. The recovered atomized powder was then subjected to hot pressing.

[0082] Test Example 5 A test was carried out under the same conditions as Test Example 2, except that the composition was changed to a CuAl intermetallic compound of 50.0 at %±0.5 at % Al, with the balance being Cu and unavoidable impurities.

[0083] Test Example 6 A test was carried out under the same conditions as Test Example 5, except that the holding time of the hot press was changed to 5 hours.

[0084] The results are shown in Table 1. SEM photographs of Test Examples 1 and 3 are shown in FIGS.

[0085] A comparison of Test Example 1 and Test Example 2 showed that the pore area could be reduced by increasing the holding time during hot pressing. It was also shown that the Vickers hardness increased accordingly.

[0086] A comparison of Test Examples 1, 3, and 4 showed that the pore area can be reduced by appropriately adjusting the particle size distribution of the atomized powder. It was also shown that the Vickers hardness increases accordingly.

[0087] In particular, the fact that the pore area ratio was large in Test Examples 1 and 4 indicates that simply shifting the particle size distribution of the atomized powder toward smaller sizes does not necessarily result in a smaller pore area ratio. In other words, it was shown that appropriate adjustment of the particle size distribution of the atomized powder is necessary.

[0088] A comparison of Test Example 5 and Test Example 6 showed that the pore area could be reduced by increasing the holding time during hot pressing. It was also shown that the Vickers hardness increased accordingly.

[0089] Furthermore, similar effects were observed in a comparison between Test Example 1 and Test Example 2, and a comparison between Test Example 5 and Test Example 6. This indicates that effects such as a reduction in pore area and an increase in Vickers hardness can be obtained regardless of the composition.

[0090] Specific embodiments of the invention have been described above. The above embodiments are merely illustrative examples, and the present invention is not limited to these embodiments. For example, technical features disclosed in one of the above embodiments may be applied to other embodiments. Furthermore, unless otherwise specified, for a particular method, the order of some steps may be interchanged, and additional steps may be added between two specific steps. The scope of the present invention is defined by the claims.

[0091] Potential Contribution to SDGs According to one embodiment of the present disclosure, cracking during sputtering can be suppressed, potentially improving product yield. Improving product yield leads to a stable supply of products and reduced loss of metal raw materials, which are limited resources. Therefore, one embodiment of the present disclosure may contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), "Build resilient infrastructure, promote inclusive and sustainable industrialization, and foster innovation," and Goal 12, "Ensure sustainable consumption and production patterns."

Claims

1. A sputtering target containing a binary alloy of Cu and Al, with the remainder consisting of unavoidable impurities, wherein the Cu and Al contents (at %) satisfy the following conditions: 0.48≦Al / (Cu+Al)≦0.70 (1) When 0.48≦Al / (Cu+Al)<0.55, the area ratio of pores within the field of view when observed with an SEM is 2.0% or less, and (2) When 0.55≦Al / (Cu+Al)≦0.70, the area ratio of pores within the field of view when observed with an SEM is 1.0% or less.

2. A sputtering target according to claim 1, wherein the contents (at%) of Cu and Al satisfy the following conditions: 0.48≦Al / (Cu+Al)≦0.52, and the area ratio of pores within the field of view when observed with an SEM is 2.0% or less.

3. A sputtering target according to claim 1, wherein the contents (at%) of Cu and Al satisfy the following conditions: 0.65≦Al / (Cu+Al)≦0.69, and the area ratio of pores within the field of view when observed with an SEM is 1.0% or less.

4. The sputtering target according to any one of claims 1 to 3, which has a bending strength of 70 MPa or more.

5. The sputtering target according to any one of claims 1 to 4, wherein the oxygen content of the sputtering target is 1000 mass ppm or less.

6. A sputtering target containing a binary alloy of Cu and Al, with the remainder being unavoidable impurities, wherein the Cu and Al contents (at%) satisfy the following conditions: 0.48≦Al / (Cu+Al)≦0.70; the oxygen content of the sputtering target is 1000 mass ppm or less; and the flexural strength is 70 MPa or more.

7. The sputtering target according to claim 6, wherein the contents (at %) of Cu and Al satisfy the following condition: 0.65≦Al / (Cu+Al)≦0.69 8. A sputtering target according to claim 6, wherein the contents (at %) of Cu and Al satisfy the following conditions: 0.48≦Al / (Cu+Al) ≦0.52; and the flexural strength is 100 MPa or more.

9. A method for producing the sputtering target according to any one of claims 1 to 8, comprising: a step of providing an ingot; a step of producing powder from the ingot by disk atomization; and a step of producing a sintered body from the powder by hot pressing, and satisfying one or more of the following conditions: the step of producing powder comprises adjusting the particle size distribution to satisfy the following conditions: D50V 40.0 to 50.0 μm D90V 65.0 to 100.0 μm; the step of producing a sintered body comprises hot pressing under the following conditions: Temperature: 500 to 700°C Pressure: 200 to 450 kgf / cm 2 Retention time: 9 hours or more Method.

10. The method for producing a sputtering target according to claim 9, wherein the step of producing the powder includes adjusting the particle size distribution to satisfy the following condition: ((D90V - D10V) / D10V) >= 1.

90.

11. The method for producing a sputtering target according to claim 9 or 10, wherein the step of producing a powder includes adjusting the particle size distribution to satisfy the following condition: ((D90V - D10V) / D50V) >= 1.

12.

12. A film produced using the sputtering target according to any one of claims 1 to 8.

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