Sputtering target assembly and film

Abstract

The purpose of the present disclosure is to provide a tungsten sputtering target assembly using a target having a low flexural strength. In one aspect, the present disclosure provides the following invention.　This sputtering target assembly comprises a target, a backing plate, and an insert, wherein: the target is composed of W; the backing plate contains Ti or a Ti alloy; the insert contains Cu or a Cu alloy; and the flexural strength of the target is at most 350 MPa.

Description

Sputtering target assembly and film

[0001] The present disclosure relates to sputtering target assemblies and films. Specifically, the present disclosure relates to tungsten sputtering target assemblies and films produced therewith.

[0002] In recent years, electrode and wiring materials have been required to have low electrical resistivity, and tungsten has attracted attention as a material that can meet this requirement.

[0003] Patent Document 1 discloses a tungsten sputtering target capable of forming a tungsten film with low resistivity. Specifically, Patent Document 1 discloses a tungsten sputtering target with an average grain size exceeding 100 μm in order to obtain a tungsten film with low resistivity.

[0004] Patent Document 2 discloses a sputtering target assembly. In the sputtering target assembly, a target and a backing plate are joined via an insert. It also discloses that metals such as W, Mo, Ti, Ta, Zr, Nb, Al, and Ti, and alloys thereof, can be used as the target material. It also discloses that Al, Ag, Cu, Ni, or alloys thereof can be used as the insert. It also discloses that Al and Al alloys, OFC (oxygen-free copper), Cu alloys, Ti, Ti alloys, SUS (stainless steel), and the like can be used as the backing plate.

[0005] JP 2019-090071 A JP 2000-239837 A

[0006] One of the technical difficulties encountered in manufacturing a sputtering target assembly is that when a brittle target is used to manufacture the sputtering target assembly, the target may crack. This problem is particularly pronounced when a target with low bending strength is used.

[0007] Therefore, an object of the present disclosure is to provide a tungsten sputtering target assembly using a target with low bending strength.

[0008] To achieve the above object, the present disclosure includes, in one aspect, the following inventions. (Invention 1) A sputtering target assembly including a target, a backing plate, and an insert, wherein the target is made of W, the backing plate contains Ti or a Ti alloy, and the insert contains Cu or a Cu alloy, and the target has a flexural strength of 350 MPa or less. (Invention 2) The sputtering target assembly of Invention 1, wherein the target has an average grain size of 100 μm or more. (Invention 3) The sputtering target assembly of Invention 1 or 2, wherein the target does not have any cracks. (Invention 4) The sputtering target assembly according to any one of Inventions 1 to 3, wherein the target is circular, and the minimum peel strength when measured at four points in the outer circumferential regions of the target and the backing plate is 6 kgf / mm 2 (Invention 5) The sputtering target assembly of Invention 4, wherein the average peel strength measured at 10 points in the entire area of ​​the target and the backing plate is 6 kgf / mm or more. 2 or more. (Invention 6) The sputtering target assembly according to any one of Inventions 1 to 5, wherein there are no traces of textured processing on the joining surface of the target. (Invention 7) The sputtering target assembly according to any one of Inventions 1 to 6, wherein the insert consists of Cu and unavoidable impurities, and the purity of the Cu is 99.9 mass% or more. (Invention 8) The sputtering target assembly according to any one of Inventions 1 to 7, wherein the insert consists of Cu and unavoidable impurities, and the oxygen content is 10 mass ppm or less. (Invention 9) A film produced using the sputtering target assembly according to any one of Inventions 1 to 8.

[0009] In one aspect, in the above invention, the insert contains Cu or a Cu alloy, which makes it possible to manufacture a sputtering target assembly by joining a target having low flexural strength and a backing plate without generating cracks.

[0010] 1 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 2 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 3 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 4 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 5 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 6 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 7 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment. 8 illustrates a location for measuring peel strength in a sputtering target assembly according to an embodiment.

[0011] 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.

[0012] 1. Sputtering Target Assembly In one embodiment, the present disclosure relates to a sputtering target assembly, which includes at least a target, a backing plate, and an insert.

[0013] 1-1. Target (Shape) The shape of the target is not particularly limited, but is typically a flat plate. Preferably, the shape of the target when viewed from above is either rectangular (e.g., square, oblong, etc.) or circular, and more preferably circular.

[0014] (Composition) The target is made of tungsten (W).

[0015] (Impurities) However, the target may contain unavoidable impurities other than tungsten. The type of unavoidable impurity is not particularly limited, and may be, for example, one or more types selected from the group consisting of carbon and oxygen. The upper limit of the amount of unavoidable impurities is not particularly limited, and may be, for example, 50 ppm by mass or less, preferably 30 ppm by mass or less, more preferably 20 ppm by mass or less, and most preferably 10 ppm by mass or less. Preferably, among the unavoidable impurities, the amount of oxygen may be 10 ppm by mass or less. The lower limit of the amount of unavoidable impurities is not particularly limited, and may be, for example, 0 ppm by mass or more, and typically 1 ppm by mass or more.

[0016] By suppressing the amount of unavoidable impurities (particularly carbon and oxygen), the effect of the impurities on the resistivity of the tungsten film is reduced.

[0017] The method for measuring unavoidable impurities is not particularly limited, and known methods used in the art may be used. For example, the carbon concentration may be measured by preparing a sample from the target or a material of the same origin as the target (e.g., scrap wood) and applying an inert gas fusion method to the sample using a carbon analyzer [CSLS600, manufactured by LECO Corporation]. For example, the oxygen concentration may be measured by preparing a sample from the target or a material of the same origin as the target (e.g., scrap wood) and applying an inert gas fusion method to the sample using an oxygen / nitrogen simultaneous analyzer [TC-600, manufactured by LECO Corporation].

[0018] (Purity) As described above, the target is made of tungsten. The purity of the target is not particularly limited, but may be 99.999 mass % (5N) or more, and preferably 99.9999 mass % (6N) or more. By increasing the purity, a tungsten film with low resistivity can be formed.

[0019] (Surface Shape) When the target has a flat shape, the target has two surfaces. The first surface is the surface to be sputtered, and the second surface is the bonding surface, i.e., the surface on the backing plate side. The surface shape of the second surface is not particularly limited.

[0020] In a preferred embodiment, the second surface is free of textured processing marks. In this specification, the term "free of textured processing marks" means that no recesses are present, and / or that even if recesses are present, the depth of the recesses is less than 0.05 mm. The depth of the recesses may be measured, for example, using a depth gauge. The location where the depth is measured is not particularly limited. For example, a straight line of a specific length (e.g., 5 cm) may be drawn at any location on the surface, and the recesses observed on the line may be measured. If multiple recesses are present on the line, the average depth of each of these recesses may be calculated.

[0021] (Relative Density) The relative density of the target is not particularly limited, but may be, for example, 99.2% or more. The reason for this is that the gas components contained in the target are reduced, which makes it possible to suppress the specific resistance of the film when it is formed. Another reason is that the generation of dust due to abnormal discharge is also suppressed. The relative density of the target is preferably 99.5% or more, more preferably 99.7% or more, and even more preferably 99.9% or more.

[0022] The relative density referred to in this specification refers to the ratio of the measured density to the theoretical density. The measured density refers to a value measured by the Archimedes method using pure water as a solvent. The theoretical density is the theoretical density when the tungsten content is 100%.

[0023] (Flexural Strength) In one embodiment, the target used in the sputtering target assembly of the present disclosure is relatively brittle. Specifically, the flexural strength of the target may be 350 MPa or less. Preferably, the flexural strength of the target may be 300 MPa or less. Although the lower limit is not particularly limited, the flexural strength of the target may be, for example, 250 MPa or more.

[0024] 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

[0025] (Average grain size) As described above, the target is made of tungsten. Here, the average grain size of the tungsten crystals is 100 μm or more. By having an average grain size equal to or greater than a predetermined value, it is possible to sufficiently reduce the resistivity when a film is formed. Because extremely low resistivity is sometimes required in the semiconductor field, the lower limit of the average grain size of the tungsten crystals may preferably be 110 μm or more, and more preferably 130 μm or more. The upper limit of the average grain size is not particularly limited, but may be, for example, 300 μm or less.

[0026] In this specification, the average grain size of tungsten crystals refers to a value measured based on the cutting method of JIS G 0551:2013. Specifically, the average grain size of tungsten crystals refers to a value determined by the following procedure: The target surface is etched using a 0.5 mol / L aqueous sodium hydroxide solution. The structure of the target surface is observed using an optical microscope, and the data of the structure image is saved. Three parallel lines are drawn in the structure image. The length of each line is not particularly limited, but is preferably long enough to include at least 10 crystal grains. The number of particles present on each line (N) and the total length of the lines (L) are used to calculate L / N, and the average of each calculation result is considered to be the average grain size of the observed area.

[0027] 1-2. Backing Plate The backing plate contains Ti or a Ti alloy. In a preferred embodiment, the backing plate is made of Ti or a Ti alloy. When the backing plate contains or is made of Ti, the term "Ti" means pure Ti. However, the Ti of the backing plate may contain unavoidable impurities (e.g., 2N5 or higher).

[0028] Ti and Ti alloys can help prevent cracking through reduced warpage during diffusion bonding with the target.

[0029] A specific example of the Ti alloy is Ti-6Al-4V. The upper limit of the thermal expansion coefficient of the Ti alloy is 11×10 -6 / °C or less, and 9 × 10 -6 / ° C. or less is more preferable. The thermal expansion coefficient of a backing plate containing Ti or a Ti alloy is also preferably within the above-mentioned upper limit range.

[0030] 1-3. Insert The insert is located between the target and the backing plate and serves to bond plates that cannot be bonded by the target and the backing plate alone, preventing cracks and other problems. In one embodiment, the insert contains Cu or a Cu alloy. In a preferred embodiment, the insert is made of Cu or a Cu alloy. Cu or a Cu alloy is suitable for promoting bonding between a tungsten target and a backing plate containing Ti or a Ti alloy. Furthermore, Cu or a Cu alloy is a metal with a relatively high melting point. Therefore, it is possible to perform processing (e.g., pressing) at a high temperature when bonding the target and the backing plate. Furthermore, processing at a high temperature increases the peel strength between the target and the backing plate.

[0031] The insert containing Cu or a Cu alloy is not particularly limited. For example, the Cu content in the Cu alloy or the Cu content in the insert is preferably 80% by mass or more, and more preferably 90% by mass or more. The melting point of the Cu or Cu alloy used in the insert, or the melting point of the insert containing the Cu or Cu alloy, is 1000°C to 1200°C. Specific examples of Cu alloys include red brass (e.g., JIS H 3100, C2100, JIS H 3100, C2200, etc.).

[0032] Preferably, the insert is made of Cu, but the insert may contain unavoidable impurities other than Cu.

[0033] The purity of Cu in the insert is preferably high, for example, the purity of Cu may be 99.9% by mass or more, preferably 99.90% by mass or more, more preferably 99.95% by mass or more, and most preferably 99.99% by mass or more.

[0034] Examples of Cu include tough pitch copper and oxygen-free copper. Of these, oxygen-free copper is preferred. The oxygen-free copper may be Cu specified by, for example, JIS H 3100, C1020, JIS H 3510, or C1011 according to the Japanese Industrial Standards. Alternatively, the oxygen-free copper may be Cu specified by, for example, C10100, C10200, or C11000 in the UNS (unified numbering system) database.

[0035] Increasing the purity can improve the peel strength between the target and the backing plate. In a particularly preferred example, reducing the amount of oxygen as an impurity can improve the peel strength between the target and the backing plate. Another advantage is that cracks do not occur when a sputtering target assembly is manufactured using a target with low bending strength.

[0036] When the insert is made of Cu, the upper limit of the amount of oxygen as an unavoidable impurity may be 100 ppm by mass or less, preferably 10 ppm by mass or less. The lower limit of the amount of oxygen is not particularly limited, but may be, for example, 0 ppm by mass or more, typically 1 ppm by mass or more. The oxygen concentration may be measured by preparing a sample from the insert and then subjecting the sample to an inert gas fusion method using an oxygen / nitrogen simultaneous analyzer [TC-600, manufactured by LECO Corporation].

[0037] 1-4 Peel Strength of Sputtering Target Assembly In the sputtering target assembly according to one embodiment of the present disclosure, the peel strength between the target and the backing plate is high.

[0038] When bonding a target to a backing plate, it is important to have a high bonding strength, especially in the outer peripheral region, because the area of ​​the outer peripheral region is larger than the area of ​​the central region, and high bonding strength in the larger area significantly contributes to improving the strength of the bond between the target and the backing plate.

[0039] In this respect, in one embodiment, the minimum peel strength measured at four points in the outer peripheral region between the target and the backing plate of the present disclosure is 6 kgf / mm 2 It may be more than that.

[0040] When the target is circular, the four measurement points are identified using the following procedure: (A) As shown in Figure 1, draw two lines that intersect at right angles and pass through the center of the circle (first line, second line). (B) As shown in Figure 2, on the first line, identify a point whose distance from the center of the circle (the circle in Figure 1) is 8R / 10 (R is the radius). (C) As shown in Figure 2, draw a perpendicular line perpendicular to the first line from that point (third line). (D) As shown in Figure 2, from the intersection of the first line and the third line, identify two points along the third line that are 1R / 10 (first measurement point, second measurement point). (E) The same procedures (B) to (D) above are performed on the second line to identify two points that are 1R / 10 (third measurement point, fourth measurement point).

[0041] As shown in Fig. 3, in the case of a rectangle, the distance from the center position to the vertex may be regarded as the radius R of the circular pattern, and the above-mentioned steps (A) to (E) may be carried out. Alternatively, as shown in Fig. 4, in the case of a rectangle, the distance from the center position to each side may be regarded as the radius R of the circular pattern, and the above-mentioned steps (A) to (E) may be carried out. Then, test pieces may be taken from these measurement points, and a tensile test may be carried out on each test piece, and the minimum strength may be adopted.

[0042] In one embodiment, the minimum peel strength measured at four points in the outer peripheral region between the target and backing plate of the present disclosure is 6 kgf / mm 2 It may be more than 7 kgf / mm 2 More preferably, 8 kgf / mm 2 The upper limit is not particularly limited, but is preferably 10 kgf / mm 2 It may be the following:

[0043] In a further embodiment, when the target and the backing plate are bonded together, it is preferable that the bonding strength is high not only in the outer peripheral region but also in the entire region.

[0044] In this respect, the average peel strength measured at 10 points in the entire area of ​​the target and backing plate is 6 kgf / mm 2 It may be more than 8 kgf / mm 2 More preferably, 9 kgf / mm 2 The upper limit is not particularly limited, but is preferably 12 kgf / mm 2 It may be the following:

[0045] In the case of a circle, the ten measurement points are set as follows (see Figures 5 and 6). (a) The procedure for specifying the four measurement points described above is carried out (first to fourth measurement points). (b) The procedures (A) to (E) for specifying the four measurement points described above are carried out, with "8R / 10" changed to "5R / 10" (fifth to eighth measurement points). (c) The procedures (A) to (D) for specifying the two measurement points described above are carried out, with "8R / 10" changed to "1R / 10" (ninth to tenth measurement points).

[0046] On the other hand, in the case of a rectangle, for example, a square, the distance from the center position to the vertex may be regarded as the radius R of the circular pattern, as shown in FIG. 7, and the above-described steps (a) to (c) may be performed. Alternatively, in the case of a rectangle, for example, a square, the distance from the center position to each side may be regarded as the radius R of the circular pattern, as shown in FIG. 8, and the above-described steps (a) to (c) may be performed. Test specimens may then be taken from these measurement points, and a tensile test may be performed on each test specimen, and the average strength may be adopted. Note that, in the case of a rectangular target, step (c) can be performed on either the long side or the short side. Typically, step (c) is performed on the long side (see FIG. 9).

[0047] The tensile test is carried out as follows: A test piece of a laminate consisting of a target, an insert, and a backing plate is prepared, and the maximum load (kgf) at which the target and the backing plate peel off is measured. The test speed is set to 0.5 mm / min. The measured maximum load is converted into the adhesive area (mm 2 ) and divide by .

[0048] The equipment used for the tensile test is not particularly limited, but for example, a 6 mm diameter tensile test sample piece can be prepared and the peel strength can be measured using a precision universal testing machine (autograph) AG-100kNX plus manufactured by Shimadzu Corporation. The tensile test sample piece is prepared to a length that includes the target, insert, and backing plate, with the bonding surfaces of each being parallel to the surface of the tensile test sample piece.

[0049] In one embodiment, the target of the present disclosure has the above-mentioned peel strength, and this characteristic is particularly useful when the target has a large grain size (e.g., an average grain size of 40 μm or more, preferably 100 μm or more). While a large target grain size offers the advantage of lower resistance, it also tends to lower the target's strength, increasing the likelihood of cracking. One method for reducing cracking is to eliminate stress concentration points. However, a shape that eliminates stress concentration points reduces the bond strength between the target and the backing plate. In one embodiment, the target of the present disclosure contributes to avoiding or compensating for such a decrease in bond strength.

[0050] As described above, in one embodiment, the target used in the sputtering target assembly of the present disclosure is relatively brittle, which can lead to cracks in the target during manufacturing of the sputtering target assembly (e.g., when stress is applied during HIP processing, etc.).

[0051] However, in one embodiment, the sputtering target assembly of the present disclosure is manufactured using an appropriate insert and backing plate (the manufacturing method is described below), thereby reducing the likelihood of cracks occurring in the target. Thus, in one embodiment, the target is crack-free. Here, crack-free means that there are no cracks on the target surface (actually, the sputtering surface of the target) that are visible to the naked eye (0.5 cm or longer).

[0052] 2. Method of Manufacturing In one embodiment, the present disclosure relates to a method of manufacturing the sputtering target assembly described above.

[0053] The method may include, for example, the following steps: - Providing a target, an insert, and a backing plate; - Stacking the target, the insert, and the backing plate in this order from above, and bonding them by hot isostatic pressing (HIP).

[0054] The method may include steps other than those described above. For example, the method may include a step of performing machining (e.g., cutting, surface processing, surface roughening, etc.) on either the target or the backing plate. For example, the method may further include a step of coating the surface of either the target or the backing plate with another component. Alternatively, the method may further include a step of forming a layer made of another component on the surface of either the target or the backing plate.

[0055] 2-1. Target Manufacturing The step of providing the target, insert, and backing plate may include manufacturing the target. The target may be manufactured by melting and casting. In this case, further processing such as rolling and cutting may be performed. Alternatively, the target may be manufactured by sintering powder. Preferably, the target is manufactured by powder sintering.

[0056] When the target is produced by powder sintering, the production conditions are not particularly limited, and production conditions known in the art can be adopted.

[0057] Preferably, the powder sintering process may include the following steps: - Performing HP (hot pressing) - Performing HIP or rolling treatment

[0058] First, in the HP process, a predetermined mold is filled with raw tungsten powder and heat-treated under a load. The tungsten powder used here preferably has a particle size of 5 μm or less. In the HP process, the temperature is increased at an appropriate heating rate, and an appropriate load is applied for each temperature range until the temperature reaches the HP temperature, at which point it is maintained for a predetermined time. The heating rate is preferably approximately 2–10°C / min. In this HP process, it is preferable to appropriately adjust and change the applied load between the temperature range of 600–1200°C and the temperature range of 1200°C or higher. Because degassing occurs during the initial heating phase of the HP process, applying a high load during this process can result in sintering proceeding without sufficient degassing, resulting in a sintered body that does not densify and contains a large amount of residual gas components, such as oxygen, inside. Therefore, in the HP process, a low load is applied in the low-temperature range and a higher load is applied in the high-temperature range, thereby increasing the density of the sintered body and reducing the amount of residual oxygen. Specifically, the load pressure in the temperature range of 600 to less than 1200°C is 80 to 150 kgf / cm 2 The load pressure in the temperature range above 1200°C is 200 to 350 kgf / cm 2 It is preferable to set the temperature at about 1600 to 1900°C. Furthermore, incorporating several steps of maintaining the temperature at a constant temperature for a certain period of time during the heating process is effective in obtaining a high-density, randomly oriented sintered body. The HP temperature in this case is preferably about 1600 to 1900°C. A low HP temperature does not increase the density sufficiently, while a high HP temperature is undesirable because it promotes the formation of a carbide layer on the tungsten surface. A too fast heating rate is undesirable because degassing during HP does not proceed sufficiently. It is clear that a too slow heating rate is also undesirable because it leads to a decrease in productivity. The holding time in this process is about 30 to 480 minutes, and can be adjusted appropriately taking into account conditions such as temperature. The holding time at the HP temperature can also be set and adjusted in a similar manner. A vacuum atmosphere is preferred for the HP process.

[0059] In order to increase the average grain size of the tungsten crystals in the HP-treated compact and to densify the compact, it is effective to subject the HP-treated compact to HIP treatment. In one embodiment, the temperature during HIP treatment may be 1600°C or higher, and the treatment time may be 2 hours or longer. Preferably, the temperature during HIP treatment may be 1800°C or higher, and the treatment time may be 5 hours or longer. By setting the HIP treatment conditions to the above-mentioned preferred conditions, a tungsten sputtering target with an average grain size of the tungsten crystals exceeding 100 μm can be obtained. The pressure during HIP treatment is 1600 to 1900 kgf / cm. 2 The temperature can be adjusted based on the above. There is no particular upper limit on the temperature during the HIP treatment, but from the viewpoint of cost, it is preferably 2200°C or less. There is no particular upper limit on the time for the HIP treatment, but from the viewpoint of cost, it is preferably 8 hours or less. The atmosphere for the HIP treatment is preferably an inert atmosphere such as an argon atmosphere.

[0060] 2-2. Manufacturing of sputtering target assembly After manufacturing the target, the target, insert, and backing plate are assembled to manufacture the sputtering target assembly. Specifically, the target, insert, and backing plate are stacked in this order from top to bottom, and then subjected to HIP treatment to bond them together.

[0061] Regarding the HIP treatment conditions, the pressure of the HIP treatment is 1000 to 2200 kgf / cm 2 The pressure of the HIP treatment can be adjusted based on the above. Preferably, the pressure is 1700 kgf / cm 2 The temperature may be 400°C or higher, and preferably 500°C or higher. There is no particular upper limit, but it is preferable to set the temperature at a temperature that does not exceed the melting point of at least one of the insert and the backing plate, and it may be, for example, 800°C or lower.

[0062] The time may be 2 hours or more, preferably 4 hours or more. The upper limit is not particularly limited, but may be, for example, 10 hours or less.

[0063] 3. Applications The sputtering target assembly 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 tungsten film produced using the sputtering target assembly described above, and a method for producing the same. Preferably, in one embodiment, the present disclosure relates to a semiconductor having a tungsten film produced using the sputtering target assembly described above, and a method for producing the same.

[0064] For example, the manufacturing method may include steps of placing a substrate and a sputtering target assembly 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.

[0065] In a sputtering target assembly according to an embodiment of the present disclosure, cracks do not occur despite the use of a target with low bending strength. Furthermore, the sputtering target assembly according to an embodiment of the present disclosure has high peel strength. Therefore, the sputtering target assembly according to an embodiment of the present disclosure is advantageous in that it reduces the occurrence of problems during sputtering.

[0066] Multiple types of tungsten targets were prepared. Specifically, multiple tungsten targets with various average particle sizes were prepared (see "(Average particle size)" in "1-1. Target" for particle size measurement methods). In Examples 1, 2, and 3 and Comparative Examples 1 and 2, the optical microscope was set to 50x magnification, three lines of approximately 1900 μm were drawn, L / N was calculated, and the average of each calculation result was calculated in 5 μm increments (for example, 130 μm when the ratio was 127.5 μm or greater but less than 132.5 μm). In Reference Example 1, the optical microscope was set to 200x magnification, three lines of approximately 475 μm were drawn, L / N was calculated, and the average of each calculation result was calculated in 5 μm increments.

[0067] The flexural strength was measured using scraps of the target (see "(Flexural Strength)" in "1-1. Target" for the measurement of flexural strength). Ten scraps were taken from the 1R / 2 portion of the target and measured, and the average value of the maximum stress is shown in Table 1. The arithmetic mean roughness Ra of the scraps is, for example, 2 to 5.5 μm. Note that the flexural strength of the sample of Comparative Example 2 was not measured, but it is considered to be similar to that of the samples of Examples 1 to 3 and Comparative Example 1.

[0068] Regarding the inserts, inserts made of Al (Comparative Example 2 and Reference Example 1) and inserts made of Cu (Examples 1 to 3 and Comparative Example 1) were prepared. For the inserts made of Cu, inserts made of oxygen-free copper (JIS H 3100, C1020) and tough pitch copper (JIS H 3100, C1100) were used.

[0069] In Comparative Example 2 and Reference Example 1, in order to strengthen the bond between the target and the backing plate, the bonding surface on the target side was subjected to uneven processing by the method described in WO2016 / 017432.

[0070] Regarding the backing plates, a backing plate made of CuZn (Comparative Examples 1 and 2 and Reference Example 1, Cu 63 mass %, Zn 37 mass %), a backing plate made of Ti (Examples 1 and 2), and a backing plate made of a Ti alloy (specifically, Ti-6Al-4V) (Example 3) were prepared.

[0071] [Correction based on Rule 91 17.09.2025] Based on the combination conditions shown in Table 1, the target, insert, and backing plate were stacked in this order from top to bottom. The stack was then subjected to HIP treatment. The HIP treatment pressure was 1800 kgf / cm. 2 The temperature was set to 100 to 300°C / h. The atmosphere was set to argon gas. The temperature and time were set as shown in Table 1.

[0072] After bonding by HIP treatment, the presence or absence of cracks on the sputtering surface of the target was visually confirmed. Then, from the sputtering target assembly where no cracks occurred, sample pieces were cut out at the locations shown in Figure 5. Then, each sample piece was pulled in a direction perpendicular to the bonding surface of the target at a speed of 0.5 mm / min, and the peel strength was measured. The measurement was performed using a precision universal testing machine (autograph) AG-100kNX plus manufactured by Shimadzu Corporation.

[0073] Table 1 shows the minimum peel strength when measured at four points in the outer peripheral region (see FIGS. 1 and 2) and the average peel strength when measured at 10 points in the entire region (see FIGS. 5 and 6).

[0074]

[0075] Compared with the sputtering target assembly (Comparative Example 1) in which the backing plate was made of CuZn, the sputtering target assemblies (Examples 1 to 3) in which the backing plate was made of Ti or a Ti alloy were manufactured without cracking. Similarly, compared with the sputtering target assembly (Comparative Example 2) in which the insert was made of Al, the sputtering target assemblies (Examples 1 to 3) in which the insert was made of Cu were manufactured without cracking. Furthermore, the sputtering target assemblies of Examples 1 to 3 ensured sufficient peel strength in the outer peripheral region and the entire region. Comparing Reference Example 1 with Examples 1 to 3, it was found that Examples 1 to 3 achieved even higher peel strength than Reference Example 1, in which the peel strength was enhanced by roughening.

[0076] 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.

Claims

1. A sputtering target assembly comprising a target, a backing plate, and an insert, wherein the target is made of W, the backing plate contains Ti or a Ti alloy, the insert contains Cu or a Cu alloy, and the flexural strength of the target is 350 MPa or less.

2. The sputtering target assembly of claim 1, wherein the average grain size of the target is 100 μm or more.

3. The sputtering target assembly of claim 1 or 2, wherein the target is free of cracks.

4. A sputtering target assembly according to any one of claims 1 to 3, wherein the target is circular, and the minimum peel strength measured at four points on the outer circumferential region of the target and the backing plate is 6 kgf / mm 2 This completes the sputtering target assembly.

5. The sputtering target assembly of claim 4, wherein the average peel strength measured at 10 points across the entire area of ​​the target and the backing plate is 6 kgf / mm 2 This completes the sputtering target assembly.

6. A sputtering target assembly according to any one of claims 1 to 5, wherein the joining surface of the target is free from uneven processing marks.

7. A sputtering target assembly according to any one of claims 1 to 6, wherein the insert consists of Cu and unavoidable impurities, and the purity of the Cu is 99.9 mass % or more.

8. A sputtering target assembly according to any one of claims 1 to 7, wherein the insert consists of Cu and unavoidable impurities, and the amount of oxygen is 10 mass ppm or less.

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

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