Molybdenum-containing materials

Abstract

A molybdenum-containing material having a crystal grain size of 25 [mu] m or more, a density of 10.15 g / cm3 or more, a molybdenum content of 99.95 mass% or more, and a mass ratio of an intra-grain tungsten content / grain boundary tungsten content (intra-grain W / grain boundary W) of 0.8 or less.

Description

Technical Field

[0001] The present disclosure relates to molybdenum-containing materials. This application claims priority based on Japanese Patent Application No. 2023-176718 filed on October 12, 2023. All the descriptions recorded in the Japanese patent application are incorporated herein by reference. Background Art

[0002] Conventionally, molybdenum plates have been disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-69628 (Patent Document 1), International Publication No. 2019-176962 (Patent Document 2), Japanese Patent Application Laid-Open No. 2005-133198 (Patent Document 3), Japanese Patent Application Laid-Open No. 2015-221937 (Patent Document 4),

[0003] Japanese Patent Publication No. 2-24901 (Patent Document 5), and Japanese Patent Application Laid-Open No. 2012-201930 (Patent Document 6).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-69628

[0007] Patent Document 2: International Publication No. 2019-176962

[0008] Patent Document 3: Japanese Patent Application Laid-Open No. 2005-133198

[0009] Patent Document 4: Japanese Patent Application Laid-Open No. 2015-221937

[0010] Patent Document 5: Japanese Patent Publication No. 2-24901

[0011] Patent Document 6: Japanese Patent Application Laid-Open No. 2012-201930 Summary of the Invention

[0012] The molybdenum-containing material of the present disclosure has a crystal grain size of 25 μm or more, a density of 10.15 g / cm 3 or more, a molybdenum content of 99.95 mass% or more, and the ratio of the intragranular tungsten content to the

[0013] grain boundary tungsten content (intragranular W / grain boundary W) is 0.8 or less. Brief Description of the Drawings

[0014] Figure 1 Figure 1 is a photograph showing an example of the structure of primary recrystallized grains of the molybdenum-containing material.

[0015] ​​Figure 2 Figure 2 is a photograph showing an example of the structure of secondary recrystallized grains of a molybdenum-containing material.

[0016] Figure 3 Figure 3 is a diagram of an apparatus for measuring the ease of deformation at high temperatures. DETAILED DESCRIPTION

[0017] [Problems to be Solved by the Present Disclosure]

[0018] High-quality molybdenum materials are required.

[0019] [Description of Embodiments of the Present Disclosure]

[0020] First, embodiments of the present disclosure will be listed and described.

[0021] In Patent Document 1, a technique for suppressing particle generation by covering the side surface and the backplane (BP) surface of a sputtering target with a metal foil or plate is disclosed.

[0022] In Patent Document 2, it is disclosed that by making the content rate of the molybdenum-containing material 99.999%

[0023] or more, the relative density 98% or more, the average particle diameter 45 μm or less, and the radiation dose 0.03 cph / cm 2 or less, particles can be reduced.

[0024] In Patent Document 3, it is disclosed that by making the content rate of the molybdenum-containing material 99.99%

[0025] or more and the relative density 98% or more, particles can be reduced. Manufacture is performed using HIP.

[0026] In Patent Document 4, it is disclosed that by making the aspect ratio of the crystal structure of the molybdenum-containing material 3 or more, the sputtering rate can be adjusted to obtain a long-life target.

[0027] In Patent Document 5, it is disclosed that the average particle diameter of the molybdenum-containing material is in the range of 15 to 150 mm, and the thickness direction of the crystal grains is 1 / 5 or more of the plate thickness.

[0028] In Patent Document 6, it is disclosed that in the depth direction of the plate thickness, at a depth of 1 / 5 from the surface of the molybdenum-containing material, there is a region where the peak intensities of X-ray diffraction (110) and (220) are less than the peak intensity of (211).

[0029] 1. (Description of the Product)

[0030] ​​​​The present disclosure relates to a molybdenum-containing material in which the amount of grain boundary impurities, crystal grain size, density, and molybdenum content are controlled. It has been found that effects can be obtained by setting the following characteristic values within a specified range.

[0031] <Crystal grain size>

[0032] The crystal grain size is 25 μm or more and less than 1 mm.

[0033] As the primary recrystallization grain size, the preferred range is 45 μm or more and less than 1 mm.

[0034] As the secondary recrystallization grain size, the preferred range is 1 mm or more.

[0035] As the secondary recrystallization grain size, the more preferred range is 10 mm or more.

[0036] If it is within this range, W and K within the particles can be reduced, and the number of particles generated can be further reduced.

[0037] <Impurity content ratio: inside the grain / grain boundary>

[0038] The mass ratio of the tungsten content inside the grain to the tungsten content at the grain boundary (W inside the grain / W at the grain boundary) is 0.8 or less.

[0039] Preferably, in the case of primary recrystallization, the mass ratio of the potassium content inside the grain to the potassium content at the grain boundary (K inside the grain / K at the grain boundary) is 0.7 or less.

[0040] Preferably, in the case of secondary recrystallization, W inside the grain / W at the grain boundary is 0.7 or less.

[0041] More preferably, in the case of secondary recrystallization, K inside the grain / K at the grain boundary is 0.6 or less.

[0042] <Density>

[0043] The density is 10.15 g / cm 3 (relative density 99.5%) or more.

[0044] The preferred range is 10.18 g / cm 3 (relative density 99.8%) or more.

[0045] If it is within this range, the influence of voids in the target on film formation is small.

[0046] <Molybdenum content>

[0047] The molybdenum content is 99.95 mass% or more.

[0048] The preferred range is 99.999 mass% or more.

[0049] If it is within this range, the particles generated by impurities can be further reduced.

[0050] <Tungsten content>

[0051] The tungsten content is preferably 200 ppm or less. More preferably, it is 90 ppm or less. If it is within this range, the W segregated at the grain boundaries has no adverse effect on the generation of particles.

[0052] <Potassium content>

[0053] The potassium content is preferably 20 ppm or less. Preferably, it is 10 ppm or less. If it is within this range, the potassium segregated at the grain boundaries has no adverse effect on the generation of particles.

[0054] As their effect, the number of particles generated in the thin film formed using the sputtering target produced according to the present disclosure is, for example, 35 particles / mm 2 or less.

[0055] The sheet resistance (thickness 300 nm) of the thin film formed using the sputtering target produced according to the present disclosure is 1.5 Ω / square or less.

[0056] Preferably, the following characteristics are exhibited.

[0057] Number of particles generated: 15 particles / mm 2 or less.

[0058] Sheet resistance of thin film (thickness 300 nm): 1.2 Ω / square or less.

[0059] Regarding the number of particles generated, by setting the number of particles of 20 nm to 1 μm to 35 or less, a thin film with a quality suitable for a reflective mask blank can be obtained.

[0060] In addition, during heat treatment at 1800 °C, secondary recrystallization occurs, and the grains grow to 1 mm or more, more preferably 10 mm or more, and the grain boundaries are reduced. As a result, the number of particles generated can be further suppressed. In addition, the high-temperature deformation resistance of the plate is also improved.

[0061] 2. (Manufacturing method and examples)

[0062] <Manufacture of molybdenum sputtering target>

[0063] Based on Process 1: Molybdenum raw material powder, Process 2: CIP, Process 3: Sintering, Process 4: Hot rolling, Process 5: Heat treatment, Process 6: Cutting, Process 7: Cutting and grinding, Process 8: Bonding and joining, a molybdenum sputtering target is manufactured.

[0064] Process 1: Molybdenum raw material powder

[0065] As the molybdenum powder used as a raw material, a powder having a molybdenum content of 99.95 mass% or more and a particle size of 1 to 10 μm measured by the FSSS method is used as the starting raw material.

[0066] When the molybdenum content is less than 99.95 mass%, the molybdenum content in the sputtered thin film decreases, and defects caused by impurities also occur.

[0067] When the Fsss particle size is less than 1 μm, the fire hazard of the powder increases, and when it exceeds 10 μm, it is difficult to perform sintering in powder metallurgy.

[0068] At this time, in order to make W and K slightly segregate toward the grain boundary due to grain boundary migration during the sintering stage, molybdenum powder with excellent sinterability can be used (for example, a molybdenum-containing powder having an average particle size of 0.1 μm or more and 10 μm or less based on the Fsss method, a molybdenum content of 99.99 mass% or more, and a compressive deformation strength of 100 MPa or more and 200 MPa or less).

[0069] Process 2: CIP

[0070] The above molybdenum powder is filled into a specified rubber container and pressure formed by isostatic pressing (CIP). The CIP pressure is set to 1 to 3 tons / cm 2 , preferably set to 2.0 tons / cm 2 .

[0071] When the pressure is lower than this pressure, sintering fracture caused by insufficient strength of the compact occurs, and a pressure higher than this pressure is not practical industrially.

[0072] Process 3: Sintering

[0073] When the above-obtained compact is sintered in a hydrogen atmosphere at a sintering temperature of 1600 °C or higher and 2300 °C or lower, preferably 1800 °C, for 3 to 20 hours, a molybdenum sintered body having a density of about 9.7 g / cm 3 is obtained.

[0074] At a temperature lower than 1600 °C, the density after sintering is insufficient, and a temperature of 2300 °C or higher is not practical industrially.

[0075] At this time, in the case of using molybdenum powder with poor sinterability, it is difficult for W and K to slightly segregate toward the grain boundary due to grain boundary migration during the sintering stage. However, even in the case of using molybdenum powder with poor sinterability, by adjusting the length of the sintering time, the same effect as when using molybdenum powder with excellent sinterability can be obtained. This is an effect manifested by sintering, and the adjustment of sintering conditions can adjust not only the time but also the hydrogen amount and temperature.

[0076] Process 4: Hot rolling

[0077] The molybdenum sintered body obtained above was inserted into a hydrogen heating furnace at 1100-1400°C and then hot rolled. When the material cooled, it was heated and rolled repeatedly until the target thickness was reached. The density after hot rolling reached 10.15-10.22 g / cm 3 , molybdenum plate with fibrous structure extending in the rolling direction.

[0078] Process 5: Heat treatment

[0079] The molybdenum plate obtained above is heat-treated at a temperature of 950° C. or higher for 0.5 to 10 hours. Recrystallization occurs by the heat treatment, and a molybdenum plate having an equiaxed grain structure is obtained.

[0080] Figure 1 This is a photograph showing an example of the structure of primary recrystallized grains of a material containing molybdenum.

[0081] Figure 2 This is a photograph showing an example of the structure of secondary recrystallized grains of a material containing molybdenum.

[0082] <Primary recrystallization>

[0083] like Figure 1 As shown, although the primary recrystallization temperature of the molybdenum plate varies somewhat depending on the manufacturing conditions, it is usually around 950°C to 1700°C, because the fibrous structure after hot pressing and stretching grows into equiaxed grains with a grain size of tens to hundreds of μm (several mm depending on the manufacturing conditions / temperature).

[0084] <Secondary recrystallization>

[0085] like Figure 2 As shown, the secondary recrystallization of the molybdenum plate needs to be raised to a temperature higher than the primary recrystallization, which usually occurs at a temperature above 1700°C. However, the difficulty of secondary recrystallization varies depending on the manufacturing conditions. Secondary recrystallization is a phenomenon in which one of the adjacent primary recrystallization grains swallows up other grains and grows. When heated for a long time (for example, 5 hours or 10 hours) at a certain temperature (for example, 1800°C or 2000°C) or above, the grain growth proceeds rapidly and grows into a huge crystal of more than 10 mm. Usually, heat treatment at a high temperature of more than 2000°C will cause secondary recrystallization in a short time, but in view of energy costs, etc., the benchmark is whether the grain size reaches more than 1 mm at 1800°C×5h, which is easy to implement in industry.

[0086] Process 6: Cutting

[0087] The recrystallized molybdenum plate obtained above is cut into a circular plate using water jetting to obtain a molybdenum circular plate. At this time, in order to improve the cutting efficiency, abrasive grains or the like can also be used. In the case where the shape of the target is square, it is cut into a square plate.

[0088] Process 7: Cutting and grinding

[0089] The surface of the above molybdenum circular plate is cut to a specified thickness by cutting, the oxide film on the surface is removed, and the flatness is improved. The outer periphery is also cut to a specified size. Then, for example, the surface is ground using a GC grindstone and finished to a Ra of 1.6 μm or less.

[0090] Process 8: Bonding and joining

[0091] A back plate (made of Cu or the like) and a joining material (made of In or the like) that match the sputtering device are prepared, and the above molybdenum circular plate and the back plate are heated using a hot plate and pasted together with the joining material. By performing this bonding and joining, a molybdenum sputtering target is obtained.

[0092] <Summary of the embodiment>

[0093] Molybdenum plates are made from various molybdenum raw material powders, heat-treated at 1300 °C for 1 h, and the crystal grain size is evaluated.

[0094] In addition, it was also evaluated whether each material undergoes secondary recrystallization by heat treatment at 1800 °C for 5 h without the above heat treatment at 1300 °C for 1 h.

[0095] Sputtering targets were manufactured using these materials. A film formation test was performed using the target, and the number of particles generated and the film resistance of the thin film were measured.

[0096] [Details of the embodiments of the present disclosure]

[0097] <Embodiment>

[0098] As raw materials, powders containing molybdenum were grouped according to each characteristic in Table 1 below and multiple were prepared.

[0099] [Table 1]

[0100]

[0101] The "powder W content rate" is the tungsten content rate in the molybdenum-containing powder. The "powder K content rate" is the potassium content rate in the molybdenum-containing powder. The five groups of powder raw materials are molybdenum-containing powders: having an average particle size of 0.1 μm or more and 10 μm or less based on the Fsss method, a molybdenum content rate of 99.99 mass% or more, and a compressive deformation strength of 100 MPa or more and 200 MPa or less, which were filed on the same day as this application. The "Fsss particle size" is the average particle size based on the Fsss method.

[0102] Among all the raw materials, the tungsten content rate did not change during sintering, but the potassium content rate decreased.

[0103] The above molybdenum raw material powder was subjected to Processes 1 to 8 to obtain a molybdenum target with a diameter φ of 4 inches (4 × 2.54 cm). The details are shown in Tables 2 to 5.

[0104] [Table 2]

[0105]

[0106] Heat treatment at 1300°C × 1 h

[0107] [Table 3]

[0108]

[0109] Heat treatment at 1800°C × 5 h [Table 4]

[0110]

[0111] [Table 5]

[0112]

[0113] In order to perform the heat treatment process (Process 5) under two conditions, the same plate was produced by hot rolling through Processes 1 to 4, the plate was cut, and two circular plates of the same quality were taken from each. Any one of the first heat treatment condition or the second heat treatment condition was applied to each circular plate.

[0114] First heat treatment condition: Specimen numbers 101 - 117, 201 - 212

[0115] Second heat treatment condition: Specimen numbers 118 - 136, 213 - 222

[0116] Process 1: Molybdenum raw material powder

[0117] Powder containing molybdenum with an Fsss average particle size of 4 - 5 μm was prepared.

[0118] Process 2: CIP

[0119] CIP was carried out under a pressure of 2.0 tons / cm 2 of.

[0120] Process 3: Sintering

[0121] The sintering temperature was set at 1800°C. In a hydrogen atmosphere, the sintering time was adjusted at intervals of 3, 6, 10, 15, and 20 hours to obtain a sintered body with a thickness T of 10 - 40 mm. The thickness of the sintered body here affects the density after hot rolling.

[0122] Process 4: Hot rolling

[0123] Heat the molybdenum sintered body at 1300 °C and roll it until the thickness T reaches 7 mm.

[0124] Process 5: Heat treatment

[0125] To recrystallize the obtained rolled material, heat treatment is carried out under two conditions. The first heat treatment condition is heat treatment at a temperature of 1300 °C for 1 h aiming at the primary recrystallization of molybdenum. Samples under the second condition do not undergo the first heat treatment. The second heat treatment is heat treatment at a temperature of 1800 °C for 5 h aiming to study whether secondary recrystallization occurs.

[0126] Process 6: Cutting

[0127] Use a water jet to cut the plate after primary or secondary recrystallization into a circular plate with a diameter φ of 4 inches.

[0128] Process 7: Cutting and grinding

[0129] Carry out cutting on both sides of the circular plate with a thickness T of 7 mm manufactured in Process 6 and finish machining to a thickness T of about 5.5 mm. Finish machining to a thickness T of 5.0 mm by grinding using a GC grindstone, thereby obtaining a molybdenum circular plate of φ4 inches × T5.0 mm. At this time, the flatness is 0.2 mm or less, and the surface roughness is consistent with about Ra 1.0 μm.

[0130] Process 8: Bonding and joining

[0131] Use indium as the joining material to bond and join the molybdenum circular plate, which is the molybdenum-containing material after finish machining in Process 7, to the copper backplane. Thus, a sputtering target is obtained.

[0132] <Evaluation method>

[0133] <Molybdenum content rate / Impurity content rate>

[0134] Calculate with the molybdenum content rate (mass%) = 100% - 14 elements [Al, Ca, Cr, Cu, Fe, Mg, Mn, Ni, Pb, Si, Sn, Na, K, W]. Tungsten (W) is an impurity.

[0135] Na, K: Measure the content rate using atomic absorption spectrometry (contrAA 300 manufactured by Analytik Jena Co., Ltd.).

[0136] For the rest: Measure the content rate using inductively coupled plasma emission spectrometry (ICP-AES) (ICPS-8100CL type manufactured by Shimadzu Corporation).

[0137] Using oxygen as the reference value, measurement is carried out by the infrared absorption method (ON836 manufactured by LECO Corporation).

[0138] <Density>

[0139] The density is measured by the water immersion method (Archimedes' method). The plate after the heat treatment in Process 5 is cut into any size of 10 g or more. Measure the weight in air, the weight in water, and the temperature of the water. Calculate by the following formula. This is the method described in JIS Z8807.

[0140] Density = {Weight in air / (Weight in air - Weight in water)} × (Density of water - Density of air) + Density of air

[0141] In addition, for the relative density, the theoretical density of molybdenum is set to 10.22 g / cm 3 and is expressed by the following formula.

[0142] Relative density [%] = (Density / 10.22) × 100

[0143] <Crystal grain size (less than 1 mm)>

[0144] The crystal grain size is measured using the cutting method specified in JIS G 0551 (2020).

[0145] The metal structure is observed using a microscope, and the test line is set to 1500 μm. Count the number of grain boundaries (P) crossing this test line, and set the average line segment length per grain as the average crystal grain size.

[0146] Specifically, the observation surface is set to the surface equivalent to the sputtering surface. In the case of a rolled material, it is the ND surface (rolled surface).

[0147] The test lines are set to a total of 4 lines, 2 lines each vertically and horizontally, with respect to the observation surface. The area surrounded by the 4 test lines forms a square of 1500 μm × 1500 μm. The crystal grain size is calculated by the following formula.

[0148] Average crystal grain size per test line = 1500 μm / P

[0149] Crystal grain size = Average value of the average grain sizes calculated by the 4 test lines

[0150] When the crystal grain size is 1 mm or more, the above method cannot be used for measurement. First, when the crystal grain size is 1 mm, measure the crystal grain size according to the measurement method. If the crystal grain size exceeds 1 mm, the accurate crystal grain size is obtained by the following method.

[0151] <Crystal grain size (1 mm or more)>

[0152] The longitudinal and transverse lengths of the grain boundaries of 5 grains are measured visually or with a low-magnification microscope, and the average line segment length of each grain is obtained in the same manner as described above. The value obtained by averaging the average line segment lengths in the longitudinal and transverse directions respectively is taken as the crystal grain size.

[0153] <Impurity ratios W, K>

[0154] When the crystal grain size is less than 1 mm

[0155] Amount of impurities in the particles: The plate manufactured in Step 7 is finely pulverized at an extremely low temperature. Thereby, the grain boundaries are broken. Then, by acid etching, the grain boundaries are preferentially corroded. As a result, an intragranular sample is obtained. It is collected and dissolved again, and analyzed by ICP, whereby the contents of tungsten and potassium are determined and taken as the impurity content rate in the particles.

[0156] Specifically, 10 samples of 1×20×20 mm are prepared. The sample cooled with liquid nitrogen is crushed in a mortar. This is to expose the grain boundaries. Then, a sieve treatment with a mesh size of 150 μm is carried out. The acid is a mixed acid prepared by mixing hydrochloric acid (12.0 mol / dm 3 ) and nitric acid (13.8 mol / dm 3 ) in a volume ratio of 1:3 and diluting the volume to 2 times with pure water. Hereinafter, the "mixed acid" in this specification refers to this acid. The particles (the material passing through a sieve with a mesh size of 150 μm) separated by sieving after crushing are put into the mixed acid and dissolved for 8 minutes. For the remaining undissolved material, the grain boundaries are removed and used as an intragranular impurity analysis sample. This sample is further dissolved with the mixed acid, and the dissolved solution is analyzed by ICP.

[0157] Amount of impurities in the grain boundaries: The plate is finely pulverized at an extremely low temperature. Thereby, the grain boundaries are broken. After that, by acid etching, the grain boundaries are preferentially corroded. Then, by analyzing the dissolved solution containing the grain boundary components by ICP, the contents of tungsten and potassium are determined and taken as the impurity content rate of the grain boundaries.

[0158] Specifically, 10 samples of 1×20×20 mm are prepared. The sample cooled with liquid nitrogen is crushed in a mortar. This is to expose the grain boundaries. A sieve treatment with a mesh size of 150 μm is carried out. The acid used is a mixed acid containing hydrochloric acid, nitric acid and water. The particles (the material passing through a sieve with a mesh size of 150 μm) separated by sieving after crushing are put into the mixed acid and dissolved for 15 minutes to obtain a dissolved solution for grain boundary impurity analysis. The dissolved solution is analyzed by ICP.

[0159] When the crystal grain size is 1 mm or more

[0160] Amount of impurities in particles: Cut the plate into pieces with a size of 1×1×1 mm or more in a way that does not include grain boundaries to prepare samples. Set the size to 1×1×1 mm or more corresponding to the grain size. Prepare samples with a total weight of 1 g or more. For example, if the size of one sample is 1×1×1 mm, prepare 100 samples. Dissolve the samples with a total weight of 1 g or more in acid. The acid used is a mixed acid containing hydrochloric acid, nitric acid and water. Analyze the dissolved solution by ICP.

[0161] Amount of impurities in grain boundaries: Cut the plate into pieces with a size of 2×2×2 mm or more in a way that includes one grain boundary to prepare samples. Set the size to 2×2×2 mm or more corresponding to the grain size. Prepare samples with a total weight of 1 g or more. For example, if the size of one sample is 2×2×2 mm, prepare 13 samples. Dissolve the samples with a total weight of 1 g or more in acid. The acid used is a mixed acid containing hydrochloric acid, nitric acid and water. Analyze the dissolved solution by ICP.

[0162] <Sputtering film formation test>

[0163] For the sputtering of molybdenum, a SRV-4320 type magnetron sputtering device manufactured by Shinko Seiki Co., Ltd. was used. A Si substrate was opposed to a molybdenum target, and a molybdenum thin film with a target thickness of 300 nm was formed thereon. The inside of the chamber was evacuated to 5×10 -4 Pa or less. Then, argon gas was flowed at 25 sccm, and the output power was set to 500 W. The target size used was φ4 inches × T5 mm.

[0164] <Number of particles generated>

[0165] In the measurement of the number of particles in the formed molybdenum thin film, a laser microscope OPTELICS HYBRID+ manufactured by Lasertech Co., Ltd. was used. The surface unevenness was measured in a range of 1 mm×1 mm, and the unevenness with a height of 20 nm to 1 μm was defined as particles and the number thereof was counted.

[0166] <Sheet resistance of thin film>

[0167] In the measurement of the film resistance, an RT-70V type manufactured by Napson Corporation was used. The sheet resistance was measured by bringing the measurement probe into contact with the 300 nm molybdenum thin film after film formation.

[0168] <Evaluation>

[0169] The "powder group" in Tables 2 and 3 is the powder group in Table 1.

[0170] "Overall" in the "W content" column is the mass fraction of tungsten in the overall molybdenum-containing material. "Intragranular" refers to the mass fraction of tungsten within the grains. "Grain boundary" refers to the mass fraction of tungsten at the grain boundaries. "Intragranular W" / "Grain boundary W" is the ratio of W.

[0171] "Overall" in the "K content" column is the mass fraction of potassium in the overall molybdenum-containing material. "Intragranular" refers to the mass fraction of potassium within the grains. "Grain boundary" refers to the mass fraction of potassium at the grain boundaries. "Intragranular K" / "Grain boundary K" is the ratio of K.

[0172] Among sample numbers 101 to 117, the number of particles is 34 or less, and the thin film sheet resistance is 1.5 Ω or less, showing good results. In contrast, it can be seen that among sample numbers 201 to 212, the number of particles and the film resistance increase.

[0173] Among sample numbers 118 to 136, the number of particles is 29 or less, and the thin film sheet resistance is 1.5 Ω or less, showing good results. In contrast, it can be seen that among sample numbers 213 to 222, the number of particles and the film resistance increase.

[0174] The ease of secondary recrystallization and the deformation at high temperatures caused by secondary recrystallization were evaluated.

[0175] As described above, "secondary recrystallization" in Table 5 is based on whether the crystal grain size reaches 1 mm or more at 1800 °C × 5 h, which is easy to implement industrially. Moreover, in Table 5, samples with a thickness T of 1 mm, a width B of 20 mm, and a length L of 120 mm were fabricated for sample numbers 118 to 212, regardless of whether secondary recrystallization was performed.

[0176] Figure 3 It is a diagram of a device for measuring the ease of deformation at high temperatures. As Figure 3 shown, the distance between the two struts 401 is set to 100 mm. A sample 402 is placed thereon. At a temperature of 1800 °C, the state of applying a force of 150 g to the center of the sample in the direction shown by the arrow 403 is maintained for 10 hours. In the "High-temperature deformation 1800 °C × 10 h" column of Table 5, samples with a deformation amount Z less than 1 mm are designated as "A", and samples with a deformation amount Z of 1 mm or more are designated as "B". It can be seen that when secondary recrystallization is performed, the deformation amount becomes smaller.

[0177] <Effect on density>

[0178] Next, in order to study the influence on density, raw materials 1 to 5 were used in Processes 1 to 3, and the thickness of the sintered body was changed to T15 mm, T12 mm, and T10 mm to fabricate a sintered body. By rolling it to T7 mm in Process 4, the change in density after hot rolling was studied. The heat treatment temperature in Process 5 was set to 1300 °C × 1 h as the first heat treatment condition. The obtained molybdenum plate was processed into a molybdenum target through Processes 5 to 8, and film formation was carried out by sputtering.

[0179] [Table 6]

[0180] Specimen number Powder group Density adjustment method 137 1 T15mm sintered body → Rolling 138 2 T15mm sintered body → Rolling 139 3 T15mm sintered body → Rolling 140 3 T12mm sintered body → Rolling 141 4 T15mm sintered body → Rolling 142 5 T15mm sintered body → Rolling 223 1 T12mm sintered body → Rolling 224 1 T10mm sintered body → Rolling 225 1 HP 226 2 T12mm sintered body → Rolling 227 2 T10mm sintered body → Rolling 228 2 HP 229 3 T10mm sintered body → Rolling 230 3 HP 231 4 T12mm sintered body → Rolling 232 4 T10mm sintered body → Rolling 233 4 HP 234 5 T12mm sintered body → Rolling 235 5 T10mm sintered body → Rolling 236 5 HP

[0181] As a further comparison, it was manufactured by hot pressing (HP), which is usually used as a method for manufacturing molybdenum targets. In the HP of molybdenum, HP was carried out under the conditions of 1600 °C × 40 MPa × 3 h, and a molybdenum sintered body was obtained. Similarly to the rolled material, the obtained sintered body was processed into a molybdenum target through Processes 5 to 8, and film formation was carried out by sputtering. The heat treatment temperature in Process 5 was set to 1300 °C × 1 h as the first heat treatment condition.

[0182] [Table 7]

[0183]

[0184] [Table 8]

[0185]

[0186] As a result, it was found that: when the density is 10.15 g / cm 3 or less, the number of particle generations increases. In addition, even though the HP product used the same raw material powder as the rolled material, the number of particle generations was larger than that of the rolled material.

[0187] In the rolled material, significant grain boundary migration occurs during recrystallization in the heat treatment after rolling, while only sintering treatment is carried out in the HP product, so the grain boundary segregation of W and K is insufficient.

[0188] (Supplementary Note 1)

[0189] A molybdenum-containing material having a crystal grain size of 25 μm or more, a density of 10.15 g / cm 3 or more, a molybdenum content rate of 99.95 mass% or more, and a mass ratio of the in-grain tungsten content rate to the grain-boundary tungsten content rate (in-grain W / grain-boundary W) of 0.8 or less.

[0190] (Supplementary Note 2)

[0191] The molybdenum-containing material according to Note 1, wherein the crystal grain size is 1 mm or more, and the value of W in the grain / W at the grain boundary is 0.7 or less.

[0192] (Note 3)

[0193] The molybdenum-containing material according to Note 1 or 2, wherein the ratio of the potassium content rate in the grain to the potassium content rate at the grain boundary, i.e., the value of K in the grain / K at the grain boundary, is 0.7 or less.

[0194] (Note 4)

[0195] The molybdenum-containing material according to Note 3, wherein the value of K in the grain / K at the grain boundary is 0.6 or less.

[0196] (Note 5)

[0197] The molybdenum-containing material according to any one of Notes 1 to 4, having a density of 10.18 g / cm 3 (99.8%) or more.

[0198] (Note 6)

[0199] The molybdenum-containing material according to any one of Notes 1 to 5, wherein the molybdenum content rate is 99.999 mass% or more.

[0200] (Note 7)

[0201] The molybdenum-containing material according to any one of Notes 1 to 6, wherein the tungsten content rate is 200 ppm or less.

[0202] (Note 8)

[0203] The molybdenum-containing material according to any one of Notes 1 to 7, wherein the total potassium content rate is 20 ppm or less.

[0204] (Note 9)

[0205] The molybdenum-containing material according to any one of Notes 1 to 8, having the shape of a plate or a target.

[0206] It should be considered that the embodiments and examples disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is represented by the claims rather than the above description, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A molybdenum-containing material having a crystal grain size of 25 μm or more and a density of 10.15 g / cm 3 In the above, the molybdenum content is 99.95 mass % or more, and the mass ratio of the intra-grain tungsten content / the grain boundary tungsten content (intra-grain W / grain boundary W) is 0.8 or less.

2. The molybdenum-containing material according to claim 1, wherein The crystal grain size is 1 mm or more, and the value of the intra-grain W / grain boundary W is 0.7 or less.

3. The molybdenum-containing material according to claim 1 or 2, wherein: The ratio of the potassium content within the grain to the potassium content within the grain boundary, that is, the value of intra-grain K / grain boundary K is 0.7 or less.

4. The molybdenum-containing material according to claim 3, wherein: The value of the intragranular K / grain boundary K is 0.6 or less.

5. The molybdenum-containing material according to claim 1 or 2, having a density of 10.18 g / cm 3 (99.8%) or above.

6. The molybdenum-containing material according to claim 1 or 2, wherein: The content of molybdenum is 99.999 mass % or more.

7. The molybdenum-containing material according to claim 1 or 2, wherein: The tungsten content is 200 ppm or less.

8. The molybdenum-containing material according to claim 1 or 2, wherein: The potassium content is 20 ppm or less. 9 . The molybdenum-containing material according to claim 1 , which has a shape of a plate or a target.

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