Chromium sintered body, method for manufacturing the same, sputtering target, and method for manufacturing substrate with chromium film

Abstract

The present invention relates to a chromium sintered body, a method for manufacturing the same, a sputtering target, and a method for manufacturing a substrate with a chromium film. The chromium sintered body contains particles. The average KAM value of the particles is 2° or less, and the average particle diameter of the particles is greater than 150 μm and 400 μm or less.

Description

Technical Field

[0001] This disclosure relates to chromium sintered bodies and methods for manufacturing the same, sputtering targets, and methods for manufacturing substrates with chromium films. Background Technology

[0002] Chromium sputtering targets (hereinafter, also simply "targets") are widely used for forming chromium films. Chromium films are sometimes formed in mask blanks, which serve as substrates for semiconductor photomasks. If the target has a high oxygen content, impurity particles containing metal oxides, sometimes called microparticles, can be generated and mixed into the chromium film during sputtering. These microparticles can also be a major cause of short circuits in the fine wiring formed using the mask blank. Therefore, it is necessary to reduce the oxygen content of the target.

[0003] For example, Japanese Patent Application Publication No. 2015-196885 discloses an ultra-low oxygen / ultra-high purity chromium target that reduces the oxygen content to below 30 ppm. Summary of the Invention

[0004] The technical problem that the invention aims to solve

[0005] However, the target described in Japanese Patent Application Publication No. 2015-196885 has the following technical problems.

[0006] That is, although the target described in Japanese Patent Application Publication No. 2015-196885 has a low oxygen content, there is room for improvement in terms of the uniformity of chromium film thickness when forming chromium film by sputtering.

[0007] This disclosure was made in view of the above-mentioned technical problems, and its object is to provide a chromium sintered body and a method for manufacturing the same, a sputtering target, and a method for manufacturing a substrate with a chromium film. The chromium sintered body is capable of manufacturing a sputtering target that can improve the uniformity of the chromium film thickness when the chromium film is formed by sputtering, and has a low oxygen content.

[0008] The inventors have discovered that the above-mentioned technical problems can be solved through the following disclosure.

[0009] That is, the present invention is as described in the claims, and the main points of this disclosure are as follows.

[0010] (1) A chromium sintered body comprising particles having an average KAM value of less than 2° and an average particle size of more than 150 μm and less than 400 μm.

[0011] (2) The chromium sintered body according to (1) wherein the oxygen content is less than 100 ppm by mass and the relative density is greater than 99.6%.

[0012] (3) The chromium sintered body according to (1) or (2), wherein the Vickers hardness is 100 HV or higher.

[0013] (4) The chromium sintered body according to any one of (1) to (3), wherein the total content of metal impurities is less than 100 ppm by mass.

[0014] (5) A chromium sintered body according to any one of (1) to (4), wherein the average aspect ratio of the particles is 1 or more and 1.8 or less.

[0015] (6) A method for manufacturing a chromium sintered body, comprising the method for manufacturing a chromium sintered body as described in any one of (1) to (5), wherein the method comprises:

[0016] The heat treatment process involves heating the electrolytic chromium sheet at a temperature above 1200℃ and below 1400℃; and

[0017] In the firing process, after the heat treatment process, the electrolytic chromium sheet is filled into a container, and the resulting filler is fired by hot isostatic pressing.

[0018] (7) The method for manufacturing chromium sintered body according to (6), wherein the atmosphere for heat treatment is an inert gas atmosphere.

[0019] (8) The method for manufacturing chromium sintered body according to (6) or (7), wherein the oxygen content of the electrolytic chromium sheet is less than 130 ppm by mass.

[0020] (9) A sputtering target comprising any one of (1) to (5) a chromium sintered body.

[0021] (10) A method for manufacturing a substrate with a chromium film, wherein the substrate with a chromium film is manufactured by forming a chromium film on the substrate by sputtering using the sputtering target described in (9).

[0022] According to (1), a sputtering target can be manufactured that can improve the uniformity of chromium film thickness when forming chromium film by sputtering, and can also have a low oxygen content.

[0023] According to (2), the relative density of the chromium sintered body is higher than 99.6%, thereby suppressing abnormal discharge or particle generation and improving the film quality when a target obtained from the chromium sintered body is formed by sputtering. Furthermore, by having an oxygen content of less than 100 ppm by mass in the chromium sintered body, a target can be manufactured that reduces oxygen incorporation into the chromium film during film formation and suppresses particle generation caused by oxygen incorporation. Moreover, a target capable of forming a chromium film with higher crystallinity can also be manufactured.

[0024] According to (3), it is possible to suppress the generation of particles and to suppress the following situation: the target surface becomes high temperature due to the collision of plasma during sputtering, stress is generated on the surface, and the target cracks.

[0025] According to (4), it is possible to further suppress the brittleness of grain boundaries caused by metallic impurities in the target obtained by using chromium sintered body, further improve the strength of the target, and suppress the generation of particles when forming chromium film by sputtering.

[0026] According to (6), the above-mentioned chromium sintered body can be manufactured effectively.

[0027] According to (9), since the sputtering target of this disclosure has the above-mentioned chromium sintered body, it is possible to form a chromium film with low oxygen content when forming a chromium film by sputtering, thereby improving the uniformity of the chromium film thickness.

[0028] According to (10), since the above-mentioned sputtering target is used, when a chromium film is formed on a substrate by sputtering, a chromium film with low oxygen content can be formed, which can improve the uniformity of the chromium film thickness.

[0029] Invention Effects

[0030] According to this disclosure, a chromium sintered body and a method for manufacturing the same, a sputtering target, and a method for manufacturing a substrate with a chromium film can be provided. The chromium sintered body is capable of manufacturing a sputtering target that can improve the uniformity of the chromium film thickness when the chromium film is formed by sputtering, and has a low oxygen content. Attached Figure Description

[0031] Figure 1 This is a top view schematic diagram used to illustrate the sintered body in observation area A.

[0032] Figure 2 This is a schematic cross-sectional view used to illustrate the sintered body of part B being measured.

[0033] Figure 3 It has the same Figure 1 Top view schematic diagram of sintered bodies with different end face shapes.

[0034] Figure 4 It has the same Figure 1 and Figure 3 Top view schematic diagram of sintered bodies with different end face shapes.

[0035] Figure 5 This is a diagram showing the measurement points on the surface of the chromium film on a substrate with a chromium film.

[0036] Explanation of reference numerals in the attached figures

[0037] 1…Sintered body, 10…Chromium film, 11…Surface, 12…Back side, 13…Cross section, A…Observation area, B…Measurement part. Detailed Implementation

[0038] This disclosure is described in detail with reference to one embodiment, but it is not limited to the following embodiments.

[0039] <Chromium Sintered Body>

[0040] The chromium sintered body disclosed herein is a sintered body with chromium as the matrix (main phase), and further, a sintered body mainly composed of chromium particles (grains), or a sintered body composed of particles containing only chromium grains.

[0041] The chromium sintered body disclosed herein comprises particles with an average KAM value of 2° or less and an average particle size greater than 150 μm and less than 400 μm.

[0042] According to the chromium sintered body disclosed herein, it is possible to manufacture a sputtering target with low oxygen content and improved film thickness uniformity when a chromium film is formed by sputtering.

[0043] The following is a detailed description of chromium sintered bodies.

[0044] (Average particle size)

[0045] The average particle size of the particles constituting the chromium sintered body is greater than 150 μm and less than 400 μm. By making the average particle size greater than 150 μm and less than 400 μm, a target with low oxygen content can be manufactured. In addition, during sputtering, abnormal discharge can be suppressed, and discharge can be stably induced. The average particle size is more preferably 200 μm or more and less than 400 μm, more preferably 230 μm or more and less than 350 μm, and particularly preferably 250 μm or more and less than 300 μm. The average crystal grain size (average particle size) can be determined by the cutting method according to Appendix C of JIS G 0551:2013, wherein the average particle size is a value determined by observing the microstructure of the chromium sintered body or target and based on the average segment length of each grain of a line segment that cross-cuts the grains constituting the chromium sintered body or target. Alternatively, after grinding the cross-section of the chromium sintered body or target, electrolytic etching is performed. For the observed 100 or more (preferably 120 ± 20) particles, a particle size distribution is created based on the particle size determined by the diameter method. In this case, the average particle size can be the median (D50) of this particle size distribution. Methods for observing the microstructure of the chromium sintered body or target include observation using an optical microscope or an electron microscope.

[0046] (Average aspect ratio)

[0047] The average aspect ratio of the particles constituting the chromium sintered body is not particularly limited, but is preferably 1 or more and 1.8 or less, more preferably 1.0 or more and 1.6 or less, and even more preferably 1.05 or more and 1.2 or less. The aspect ratio refers to the ratio of the major axis to the minor axis when the particles constituting the chromium sintered body are approximately elliptical; it is a parameter indicating the isotropic nature of the particle shape. By making the average aspect ratio of the particles 1 or more, the unevenness of the target surface during film formation can be reduced, thus reducing the number of particles. On the other hand, by making the average aspect ratio of the particles 1.8 or less, the in-plane strength of the sintered body structure increases, which can suppress target breakage during film formation. Furthermore, by making the average aspect ratio 1 or more and 1.8 or less, the film formation rate is more stable when forming a chromium film by sputtering. The average aspect ratio is as follows: Using SEM-EBSD (Scanning Electron Microscope-Electron Backscatter Diffraction System, e.g., SEM: NEC, EBSD: Oxford), the microstructure of the sintered body is observed under the following measurement conditions and procedures. For all particles with uninterrupted observed contours, the major axis / minor axis values ​​when approximately elliptical are calculated, and these values ​​are arithmetically averaged to obtain the average aspect ratio. The number of observed particles is 100 or more, preferably 150 ± 20.

[0048] (Measurement conditions)

[0049] Beam conditions: accelerating voltage 20kV, irradiation current 100μA

[0050] Working distance: 10mm

[0051] Step size: 5μm

[0052] (Using the program)

[0053] Measurement Procedure: AZtec

[0054] Analysis program: AZtec Crystal

[0055] (Average KAM value)

[0056] The average KAM value of the chromium sintered body is 2° or less. KAM (Kernel Average Misorientation) is a parameter representing the residual strain within the particles; a larger value indicates a greater residual strain within the particles (grains). By keeping the average KAM value below 2°, the internal strain of the chromium sintered body can be reduced, suppressing the non-uniformity of the chromium film thickness caused by stress release during sputtering. As a result, the uniformity of the chromium film thickness is improved. From the viewpoint of improving the uniformity of the chromium film thickness, the average KAM value is preferably 1.8° or less, more preferably 1.2° or less. The average KAM value can be 1.0° or less, 0.8° or less, 0.6° or less, 0.5° or less, 0.4° or less, or 0.3° or less.

[0057] The average KAM value exceeds 0°, and examples include 0.10° or more or 0.20° or more. As particularly preferred average KAM values, examples include values ​​exceeding 0° and below 2°, 0.10° or more and below 1.0°, 0.1° or more and below 0.5°, 0.1° or more and below 0.3°, or 0.20° or more and below 0.3°.

[0058] It should be noted that the average KAM value refers to the following: For the measurement portion B within observation area A of the cross-section of the sintered body, after observing the microstructure of the sintered body using SEM-EBSD (SEM: NEC, EBSD: Oxford Instruments) under the aforementioned measurement conditions and procedures, the KAM values ​​of all particles in measurement portion B whose outlines are not interrupted are measured. These KAM values ​​are then arithmetically averaged to obtain the average KAM value. The number of observed particles is 100 or more, preferably 150 ± 20.

[0059] Here, use Figure 1 and Figure 2 The observation area A and the measurement section B are described.

[0060] Figure 1 and Figure 2 A schematic diagram of the sintered body is shown in the figure. Figure 1 This is a top view schematic diagram used to illustrate the sintered body in observation area A. Figure 2 This is a schematic cross-sectional view used to illustrate the measurement of part B of the sintered body. The shape of the sintered body is not particularly limited. Figure 1 and Figure 2 In this context, the sintered body is described as a circular plate. For example... Figure 2 As shown, the surface 11 and the back surface 12, which are the end faces of the sintered body, are both equivalent to the plane of the circular plate.

[0061] like Figure 1 As shown, the annular region on the circular surface 11 of the sintered body 1 is the observation region A. Specifically, when the distance from the center O of the circle to the outer perimeter (the radius of the circular surface 11) is set to R, the observation region A is the oblique region enclosed by the circumference C1 of the circle centered at O ​​and with a radius of 0.5R, and the circumference C2 of the circle centered at O ​​and with a radius of 0.75R.

[0062] It should be noted that, as Figure 3As shown, when the surface 11 of the sintered body is a quadrilateral, and the distance from the intersection point P of the diagonals to a point Q on the outer periphery of the quadrilateral (the outer periphery of the surface 11) is set as PQ, the observation area A is the oblique region enclosed by the periphery D1 of the quadrilateral with P as the intersection point of the diagonals of the surface 11 and a distance of 0.5PQ from P to the outer periphery, and the periphery D2 of the quadrilateral with P as the intersection point of the diagonals and a distance of 0.75PQ from P to the outer periphery.

[0063] like Figure 4 As shown, when the surface 11 of the sintered body has other planar shapes (e.g., triangles), the oblique region enclosed by perimeters E1 and E2 can be used as observation region A. Perimeter E1 is a region with a centroid at point G on the surface 11 of the sintered body that forms the center of gravity of the planar shape, and similar to the planar shape with a similarity ratio of 0.5. Perimeter E2 is a region with a centroid at point G on the surface 11 of the sintered body that forms the center of gravity of the planar shape, and similar to the planar shape with a similarity ratio of 0.75. In this case, if the distance between the line segment connecting point H on the periphery of the surface 11 and the centroid G is set to GH, the distance along this line segment from the centroid G to perimeter E1 is 0.5GH, and the distance along this line segment from the centroid G to perimeter E2 is 0.75GH.

[0064] On the other hand, the measured part B refers to the area with a width of 2 mm × total thickness t (mm) in the observation area A of the cross section 13 of the sintered body 1 (refer to...). Figure 2 ).

[0065] (Relative density)

[0066] The relative density of the chromium sintered body is preferably higher than 99.6%. A relative density higher than 99.6% allows for suppression of abnormal discharge or particle generation during chromium film formation by sputtering, further improving the film quality. A relative density of 99.7% or higher is more preferred, and particularly preferred is 99.9% or higher. While a high relative density is desirable, it is acceptable as long as it is below 100%. The relative density of the chromium sintered body disclosed herein is preferably higher than 99.6% and below 100%, or higher than 99.8% and below 100%. The relative density of the chromium sintered body can be determined by the following method: The measured density of the chromium sintered body is determined according to JIS R 1634, and then divided by the true density of chromium to calculate the relative density. In this embodiment, the true density of chromium can be set to 7.19 g / cm³. 3 .

[0067] (Oxygen content)

[0068] The oxygen content of the chromium sintered body is preferably 100 ppm by mass or less, more preferably 30 ppm by mass or less, and even more preferably 20 ppm by mass or less. By having an oxygen content of 100 ppm by mass or less in the chromium sintered body, oxygen incorporation into the chromium film during film formation can be reduced. This allows for the manufacture of targets that suppress the generation of particulate matter caused by oxygen incorporation. Furthermore, the low oxygen content enables the manufacture of targets from which sputtered films with higher crystallinity can be obtained.

[0069] It is preferred to have a low oxygen content, but it can be 0.1 ppm or more, 2 ppm or more, or 5 ppm or more.

[0070] Examples of preferred oxygen contents include 0.1 ppm or more and 100 ppm or less, 0.1 ppm or more and 30 ppm or less, or 2 ppm or more and 20 ppm or less.

[0071] The oxygen content is a value measured using an oxygen / nitrogen analyzer (e.g., ON736, manufactured by LECO).

[0072] (Vickers hardness)

[0073] The Vickers hardness of the chromium sintered body is preferably 100 HV or higher. In this case, it is possible to suppress target breakage caused by surface stress generated by the collision of plasma during sputtering, and also to suppress the generation of microparticles.

[0074] The Vickers hardness of the chromium sintered body is more preferably 110 HV or higher, and particularly preferably 120 HV or higher.

[0075] The Vickers hardness of the chromium sintered body is preferably 180 HV or less, more preferably 150 HV or less, and even more preferably 130 HV or less. Examples of preferred Vickers hardness include 100 HV or more and 180 HV or less, 110 HV or more and 150 HV or less, or 110 HV or more and 130 HV or less.

[0076] Vickers hardness can be determined using a method based on JIS-Z-2244-1:2009. Examples of conditions for measuring Vickers hardness are as follows.

[0077] Test sample thickness: 5 ± 0.5 mm

[0078] Measurement load: 10 kgf

[0079] (Content of metallic impurities)

[0080] The total content of metallic impurities in the chromium sintered body can be less than 150 ppm by mass or less than 100 ppm by mass.

[0081] The total content of metallic impurities in the chromium sintered body is preferably less than 100 ppm by mass. In this case, the brittleness of grain boundaries caused by metallic impurities can be further suppressed, the strength of the target can be further improved, and as a result, the generation of particulate matter during the formation of the chromium film by sputtering can be suppressed.

[0082] Chromium sintered bodies may contain metallic impurities as long as a target with practical strength can be obtained. Examples of total metallic impurity content in chromium sintered bodies include 0 ppm or more by mass, 20 ppm or more by mass, 50 ppm or more by mass, or 80 ppm or more by mass. Examples of total metallic impurity content in the chromium sintered bodies of this disclosure include 0 ppm or more and 150 ppm or less by mass, 50 ppm or more and 150 ppm or less by mass, or 80 ppm or more and 100 ppm or less by mass.

[0083] The aforementioned metallic impurities may include metals other than chromium (Cr), such as Fe, Al, Si, and Cu. It should be noted that the total content of metallic impurities in this disclosure is the sum of the contents of Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Th, and U.

[0084] It is preferable to have fewer metallic impurities, but the following ranges can be cited as examples of the ranges for the content of each metallic impurity.

[0085] The Fe content must be above 0.5 ppm by mass and below 40 ppm by mass, or above 0.5 ppm by mass and below 25 ppm by mass.

[0086] The Pb content can be 0.05 ppm or more and 1 ppm or more, or 0.05 ppm or more and 0.3 ppm or less.

[0087] The Ca content can be 5 ppm or less by mass, or 3 ppm or less by mass, preferably 0 ppm or more and 1.2 ppm or less by mass, and more preferably 0 ppm or more and 1 ppm or less by mass.

[0088] The Mg content can be 5 ppm or less by mass, or 3 ppm or less by mass, preferably 0 ppm or more and 5 ppm or less by mass, and more preferably more than 0 ppm by mass and 0.1 ppm or less by mass.

[0089] The Na content can be 10 ppm or less, 5 ppm or less, or 3 ppm or less, preferably 0 ppm or more and 8 ppm or less, or more than 0 ppm or less and 5 ppm or less.

[0090] The K content can be 5 ppm or less by mass, or 3 ppm or less by mass, preferably 0 ppm or more and 5 ppm or less by mass, or more than 0 ppm and less than 1 ppm by mass.

[0091] The preferred ranges for the content of each non-metallic impurity are described below. Examples of non-metallic impurities include sulfur, carbon, oxygen, hydrogen, and chlorine. It should be noted that oxygen has a greater impact than sulfur and carbon; therefore, for convenience, oxygen is not included in the list of non-metallic impurities in this specification.

[0092] Examples of sulfur content include 0.1 ppm by mass or more and 30 ppm by mass or 0.1 ppm by mass or more and 20 ppm by mass.

[0093] Examples of carbon content include 0.1 ppm by mass or more and 30 ppm by mass or 0.1 ppm by mass or more and 20 ppm by mass.

[0094] <Method for manufacturing chromium sintered bodies>

[0095] The method for manufacturing chromium sintered bodies disclosed herein includes: a heat treatment step in which an electrolytic chromium sheet is heat-treated at a temperature above 1200°C and below 1400°C; and a firing step in which, after the heat treatment step, the electrolytic chromium sheet is filled into a container, and the resulting filler is fired by HIP treatment (hot isostatic pressing).

[0096] The above manufacturing method can effectively manufacture the chromium sintered body.

[0097] The following is a detailed description of the above-mentioned heat treatment process and firing process.

[0098] (Heat treatment process)

[0099] Through a heat treatment process, electrolytic chromium sheets are brought to a state suitable for use in the firing process. Electrolytic chromium sheets used in the heat treatment process refer to flake-shaped metallic chromium that has been purified by electrolysis.

[0100] The electrolytic chromium sheet can be either an uncrushed or a pulverized sheet, but is preferably an uncrushed sheet. In this case, oxidation of the electrolytic chromium sheet caused by pulverization energy, the introduction of impurities from the pulverizing medium into the electrolytic chromium sheet, and strain generated in the electrolytic chromium sheet due to pulverization can be prevented. Therefore, it is also possible to manufacture a chromium sintered body that produces a target with reduced oxygen and impurity content, and suppresses non-uniformity in the chromium film thickness caused by stress release during sputtering.

[0101] The average particle size of the electrolytic chromium sheet is not particularly limited, but is preferably 250 μm or more, more preferably 5000 μm or more, and even more preferably 10000 μm or more. The average particle size of the electrolytic chromium sheet is preferably 100000 μm or less, more preferably 50000 μm or less. Examples of preferred average particle sizes include 250 μm or more and 10 cm or less, 1 mm or more and 15 mm or less, or 5 mm or more and 15 mm or less.

[0102] The average particle size of electrolytic chromium flakes is determined from the median particle size when the raw material is screened using a multi-stage sieve based on JIS Z8815.

[0103] The oxygen content of the electrolytic chromium sheet is preferably 100 ppm by mass or less, more preferably 30 ppm by mass or less, even more preferably 20 ppm by mass or less, even more preferably 10 ppm by mass or less, and particularly preferably 7 ppm by mass or less. By reducing the oxygen content of the electrolytic chromium sheet, the oxygen content of the target can be reduced. A low oxygen content is preferred, but it can be more than 0 ppm by mass or more than 1 ppm by mass. Examples of preferred oxygen contents for the electrolytic chromium sheet include more than 0 ppm by mass and less than 100 ppm by mass, more than 0 ppm by mass and less than 30 ppm by mass, or more than 1 ppm by mass and less than 20 ppm by mass.

[0104] The oxygen content is a value measured using an oxygen / nitrogen analyzer (e.g., ON736, manufactured by LECO).

[0105] The content of metallic impurities in the electrolytic chromium sheet is preferably 130 ppm by mass or less, more preferably 100 ppm by mass or less. By reducing the content of metallic impurities in the electrolytic chromium sheet, the impurity content of the target can be reduced. It is preferable to have a low content of metallic impurities, but it can be more than 0 ppm by mass, or more than 1 ppm by mass, more than 10 ppm by mass, or more than 50 ppm by mass. Examples of preferred metallic impurity contents include more than 0 ppm by mass and less than 130 ppm by mass, or more than 50 ppm by mass and less than 130 ppm by mass.

[0106] The electrolytic chromium sheet preferably has high chromium purity, preferably 99.95% (3N5) ​​or higher, more preferably 99.99% (4N) or higher. In particular, when the average particle size of the electrolytic chromium sheet is 250 μm or higher, the specific surface area of ​​the resulting chromium sintered body can be reduced, resulting in low oxidation. Then, by HIP treatment and sintering, a low-oxygen / high-purity chromium target with reduced oxygen content can be manufactured without compromising the quality of the high-purity, low-oxygen chromium metal used as the starting material.

[0107] The heating temperature T1 for the electrolytic chromium sheet is above 1200°C and below 1400°C. By setting the heating temperature T1 within this range, the residual stress generated within the sheet during electrolytic deposition can be mitigated, and the strain in the resulting chromium sintered body can be reduced. Further heat treatment facilitates the filling of the electrolytic chromium sheet into the tank for HIP processing, and increases the packing density into the tank during HIP processing.

[0108] The heating temperature T1 is preferably above 1200℃ and below 1300℃.

[0109] There is no particular limitation on the heating time, but from the viewpoint of reducing strain, it is preferably 1 hour or more, more preferably 3 hours or more. The heating time can be adjusted appropriately according to the amount of starting material supplied for the heat treatment. If the productivity of chromium sintered body is taken into consideration, it is preferably 15 hours or less, more preferably 10 hours or less, and even more preferably 7 hours or less. Examples include 1 hour or more and 15 hours or less, or 3 hours or more and 10 hours or less.

[0110] The heat treatment is preferably carried out in a neutral gas atmosphere or in a vacuum. Under these conditions, oxidation of the electrolytic plate can be suppressed, and the increase in oxygen content can be prevented.

[0111] Inert gases refer to rare gases such as nitrogen or argon. Argon is preferred as an inert gas. The atmosphere for heat treatment is preferably an inert gas atmosphere, and more preferably an argon atmosphere.

[0112] (Firing process)

[0113] The firing process involves filling the electrolytic chromium sheet after the heat treatment process into a container, and then firing the resulting filler at a firing temperature T2 after HIP treatment.

[0114] Examples of containers mentioned above include cans made of soft iron.

[0115] During the firing process, the filling density of the starting material into the container is preferably 50% or more, and can be between 50% and 80%. The filling density is calculated based on the measured density of the filler and the true density of chromium (7.19 g / cm³). 3 The value is calculated based on the relative density.

[0116] Measured density = Weight of filler in the can (g) / Volume of the can (cm³) 3 )

[0117] Filler density = Measured density / True density of chromium

[0118] The firing temperature T2 is not particularly limited as long as it is the sintering temperature of the electrolytic chromium sheet. Relative to the heating temperature T1 of the electrolytic chromium sheet, it is preferably T1-100 (°C) or higher and T1+100 (°C) or lower (satisfying T2 (°C) = T1±100°C). In this case, it is possible to suppress abnormal grain growth during the firing process while suppressing strain generation, and to sinter the electrolytic chromium sheet.

[0119] As long as the sintering of electrolytic chromium sheets is carried out, there are no particular restrictions on the pressure during the firing process. From the viewpoint of effectively reducing bubbles and increasing density, the pressure during the firing process is preferably 50 MPa or more, more preferably 100 MPa or more. From the viewpoint of protecting the equipment, the pressure during the firing process is preferably 400 MPa or less, more preferably 300 MPa or less. Examples of preferred pressures during the firing process include 50 MPa or more and 400 MPa or less, or 100 MPa or more and 200 MPa or less.

[0120] There is no particular limitation on the holding time (holding time at the firing temperature) during the firing process, but from the viewpoint of stable sintering, it is preferably 1 hour or more, more preferably 3 hours or more. From the viewpoint of controlling particle size, the holding time during the firing process is preferably 10 hours or less, more preferably 5 hours or less. Examples of preferred holding times include 1 hour or more and 10 hours or less, or 3 hours or more and 5 hours or less.

[0121] (Other processes)

[0122] The filler material (heat-treated body) fired through the firing process can also be machined as needed. If it is not machined, the fired filler material will become a chromium sintered body. If it is machined, the material obtained by machining the fired filler material, excluding the fired filler material itself, will become a chromium sintered body.

[0123] Oxides sometimes form on the surface of the heat-treated body (chromium sintered body) obtained during the sintering process, and the surface roughness tends to increase. Therefore, surface grinding is preferred as a machining process. There are no particular limitations on the processing method; grinding using a surface grinder is an example. To remove the oxide scale from the surface of the heat-treated body, it is preferable to cut a portion of 0.5 mm or more from the surface.

[0124] When a modified layer is formed by machining, the thickness of the modified layer is preferably 100 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less. By making the thickness of the modified layer 100 μm or less, it is possible to further suppress the generation of microparticles due to the peeling of the modified layer. Examples of modified layers include those with a thickness of 0 μm or more and 100 μm or less, or those with a thickness of 0 μm or more and 5 μm or less.

[0125] The so-called processed altered layer refers to the layer on the surface side of the chromium sintered body, which is a layer with fine cracks formed through mechanical processing.

[0126] When there are defects in the chromium sintered body, the maximum size of the defect is preferably less than 1 mm.

[0127] Here, a scratch refers to an unevenness formed on the surface of a chromium sintered body, such as linear depressions or collision marks with an object. Furthermore, the size of a scratch refers to the maximum distance between two points on the same scratch when viewed from above.

[0128] <Splash Target>

[0129] The target disclosed herein comprises the aforementioned chromium sintered body. The target disclosed herein may further comprise a back plate attached to the aforementioned chromium sintered body.

[0130] The sputtering target disclosed herein has the aforementioned chromium sintered body, and therefore has a low oxygen content, which can improve the uniformity of chromium film thickness when forming chromium film by sputtering.

[0131] A bonding material can also be used between the target and the backing plate. Various materials can be used as the bonding material, but indium is preferred from the perspective of heat diffusion and suppression of thermal expansion during sputtering.

[0132] As a method of joining the chromium sintered body to the back plate, one or more methods selected from the group consisting of diffusion bonding, solder bonding and friction stir bonding can be cited. However, as long as the chromium sintered body and the back plate are joined with the strength required for sputtering, the joining method is not particularly limited.

[0133] There are no particular limitations on the bonding rate at the interface between the chromium sintered body and the back plate, but the bonding rate is preferably 95% or more, more preferably 99% or more, and particularly preferably 99.5% or more. The bonding rate refers to the proportion calculated by the following formula.

[0134] Bonding rate (%) = 100 × S1 / S

[0135] (In the above formula, S represents the area of ​​the overlapping surface of the chromium sintered body and the back plate when observed along the thickness direction of the back plate in the target, and S1 represents the area of ​​the part of the chromium sintered body and the back plate that are bonded together.)

[0136] By setting the bonding rate to 95% or higher, heat conduction can be promoted, and the modification and particle generation caused by heat generated during the sputtering of the chromium sintered body can be suppressed. A high bonding rate is preferred, but it is acceptable to have a bonding rate of 95% or higher and 100% or lower, 99% or higher and 100% or lower, or 99.5% or higher and 100% or lower.

[0137] The smaller the warpage of the target, the better. Specifically, it is preferred to be less than 0.5 mm. Examples include 0 mm or more and less than 0.5 mm, 0.05 mm or more and less than 0.3 mm, and 0.10 mm or more and less than 0.15 mm.

[0138] Warpage refers to the distance from the point of contact between the sputtering surface and the plane to the point on the surface of the sputtering surface that is furthest from the plane when the sputtered surface of the chromium sintered body is placed face down on a plane.

[0139] <Method for manufacturing a substrate with a chromium film>

[0140] In the method for manufacturing a substrate with a chromium film disclosed herein, the above-mentioned target is used to form a chromium film on the substrate by sputtering, thereby manufacturing a substrate with a chromium film.

[0141] According to the method for manufacturing a substrate with a chromium film disclosed herein, since the above-mentioned sputtering target is used, when a chromium film is formed on the substrate by sputtering, a chromium film with a low oxygen content can be formed, thereby improving the uniformity of the chromium film thickness.

[0142] There are no particular limitations on the substrates mentioned above; for example, at least one of glass substrates and quartz substrates can be cited, with glass substrates being preferred.

[0143] There are no particular restrictions on the temperature of the substrate when forming the chromium film; for example, it can be room temperature (25°C).

[0144] There are no particular restrictions on the type of gas used in film formation as long as it is sputtered by electrical discharge; for example, it can be argon.

[0145] There are no particular restrictions on the gas pressure during film formation; for example, it can be above 0.2 Pa and below 2 Pa.

[0146] There are no particular limitations on the power density during film formation; for example, it can be 2.5 W / cm³. 2 Above and 50W / cm 2 Below, or 5W / cm 2 Above and 10W / cm 2 the following.

[0147] Ideally, the number of abnormal discharges during film formation should be low, preferably 3 times / h or less, more preferably 1 time / h or less, and examples include 0 times / h or more and 3 times / h or 0 times / h or more and 1 time / h or less.

[0148] The smaller the standard deviation σ of the chromium film thickness, the better. Specifically, it is preferably 10 or less, and examples include 0 or more and 10 or less, or 1 or more and 8 or less. In addition, the smaller the NU as defined by the following formula, the better. Specifically, it is preferably 10% or less, and more preferably 8% or less, and examples include 0% or more and 10% or less, or 1% or more and 8% or less.

[0149] NU(%) = (Standard deviation of film thickness σ(nm) / Average film thickness (nm)) × 100

[0150] The film thickness was measured using a film thickness measuring instrument (DEKTAK) on the surface 10a of the chromium film 10 on the substrate with the chromium film. For example... Figure 5 As shown, the film thickness is measured at a point L on the surface 10a of the chromium film 10, and at 31 measurement points: 5 points, 10 points, and 15 points respectively arranged on three concentric circles J1, J2, and J3 centered on point L. Here, the outermost concentric circle J3 of the three concentric circles J1, J2, and J3 is arranged such that it surrounds an area covering at least 60% of the total area of ​​the surface 10a of the chromium film 10. The average film thickness refers to the arithmetic mean of the film thicknesses measured as described above. Furthermore, the standard deviation σ of the film thickness refers to the standard deviation calculated from the film thickness distribution obtained from the measured film thicknesses.

[0151] Example

[0152] The present disclosure will be described in more detail with reference to the embodiments and comparative examples, but the present disclosure is not limited to the following embodiments.

[0153] The methods for determining the parameters used in the examples and comparative examples are as follows.

[0154] <Average particle size of raw materials>

[0155] When raw material screening is carried out using a multi-stage sieve based on JIS Z8815, the average particle size of the raw material is the median particle size.

[0156] <Oxygen content>

[0157] The oxygen content in the raw materials and chromium sintered body was determined using an oxygen / nitrogen analyzer (ON736, manufactured by LECO).

[0158] <Impurity content>

[0159] The content of metallic impurities in the raw materials and chromium sintered bodies was determined by glow discharge mass spectrometry (GDMS) for Li, Be, B, Na, Mg, Al, Si, P, K, Ca, Sc, Ti, V, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, Th, and U. In addition, the content of non-metallic impurities (sulfur and carbon) was determined by instrumental gas analysis (IGA).

[0160] <Fill density>

[0161] The packing density is calculated based on the measured density of the packing and the true density of chromium (7.19 g / cm³) using the following formula. 3 The relative density is calculated based on ).

[0162] Measured density = Weight of filler in the can (g) / Volume of the can (cm³) 3 )

[0163] Filler density = Measured density / True density of chromium

[0164] <Average KAM Value>

[0165] like Figure 1 As shown, the annular region on the circular surface 11 of the sintered body 1 is taken as the observation region A. The measurement portion B in the observation region A of the cross-section of the sintered body (refer to...) Figure 2 The KAM values ​​of all particles (120±20) with unbroken profiles observed in measurement section B were measured using SEM-EBSD (Scanning Electron Microscope-Electron Backscatter Diffraction System, SEM: NEC, EBSD: Oxford). The arithmetic mean of their KAM values ​​was taken as the average KAM value.

[0166] (Measurement conditions)

[0167] Beam conditions: accelerating voltage 20kV, irradiation current 100μA

[0168] Working distance: 10mm

[0169] Step size: 5μm

[0170] (Using the program)

[0171] Measurement Procedure: AZtec

[0172] Analysis program: AZtec Crystal

[0173] <Average Particle Size>

[0174] After cutting and grinding the sintered body, electrolytic etching is performed. For particles (grains) with more than 100 points (120±10 points) observed by SEM, the particle size distribution is made based on the particle size determined by the diameter method, and the median (D50) of the particle size distribution is used as the average particle size of the particles constituting the sintered body.

[0175] <Average Aspect Ratio>

[0176] After cutting and grinding the sintered body, electrolytic etching is performed. For more than 100 (120±10) particles (grains) observed by SEM, the aspect ratio (= major axis / minor axis) when they are approximately elliptical is calculated, and the arithmetic mean of these aspect ratios is obtained as the average aspect ratio.

[0177] <Relative density of sintered body>

[0178] The relative density of the chromium sintered body was determined by the following method: The measured density of the chromium sintered body was determined according to JIS R 1634, and the relative density was calculated by dividing it by the true density of chromium. The true density of chromium is 7.19 g / cm³. 3 .

[0179] <Vickers Hardness>

[0180] Vickers hardness was determined according to JIS-Z-2244-1. The conditions for determining Vickers hardness were set as follows.

[0181] Test sample thickness: 5 ± 0.5 mm

[0182] Measurement load: 10 kgf

[0183] <Mean and standard deviation of film thickness>

[0184] On the surface of the chromium film on a substrate with a chromium film, the film thickness is measured using a film thickness gauge (DEKTAK), and the average value is calculated as the average film thickness. For example... Figure 5As shown, the film thickness was measured at a point L on the surface 10a of the chromium film 10, and at a total of 31 measurement points: 5 points, 10 points, and 15 points respectively arranged on three concentric circles J1, J2, and J3 centered on point L. At this time, the outermost concentric circle J3 occupies 72% of the total area of ​​the surface 10a of the chromium film 10.

[0185] In addition, the film thickness distribution is obtained based on the measured film thickness, and the standard deviation is calculated from the film thickness distribution.

[0186] <Abnormal discharge>

[0187] Abnormal discharges are detected using an arc counter. The number of abnormal discharges detected during film formation is then divided by the film formation time to determine the number of abnormal discharges per hour.

[0188] (Example 1)

[0189] 30 kg of commercially available electrolytic chromium sheet with a purity of 99.995% (4N5) and the average particle size shown in Table 1 was used as the starting material. The electrolytic chromium sheet was heat-treated at 1200°C for 10 hours in an argon atmosphere.

[0190] Next, the heat-treated starting material was filled into a soft iron can (400mm × 400mm × 200mm) at the filling density shown in Table 2. After vacuum sealing, the material was subjected to HIP treatment under the firing conditions shown in Table 2, and thus fired. After firing, a chromium sintered body (ingot) with a diameter of 216mm × 6.35mm was obtained by machining.

[0191] Next, the obtained chromium sintered body is bonded to the back plate using indium as a bonding material to fabricate the target.

[0192] Using the obtained target, sputtering was performed under the sputtering conditions shown in Table 4 to form a chromium film (chromium sputtered film) on a glass substrate, thus manufacturing a substrate with a chromium film. During film formation, the substrate temperature was set to room temperature (RT).

[0193] (Example 2)

[0194] As the electrolytic chromium sheet, an electrolytic chromium sheet having the average particle size shown in Table 1 was used. Otherwise, it was heat-treated in the same way as in Example 1. The heat-treated electrolytic chromium sheet was filled with a filling density shown in Table 2, and HIP treatment was performed under the firing conditions shown in Table 2. Otherwise, a chromium sintered body, a target, and a substrate with a chromium film were fabricated in the same way as in Example 1.

[0195] (Example 3)

[0196] As electrolytic chromium sheets, electrolytic chromium sheets having the average particle size shown in Table 1 were used, and heat treatment was performed at the heating temperature shown in Table 1. The heat-treated electrolytic chromium sheets were then filled with a filling density shown in Table 2, and HIP treatment was performed under the firing conditions shown in Table 2. Otherwise, the chromium sintered body and target were prepared in the same manner as in Example 1.

[0197] (Comparative Example 1)

[0198] Prepare 125 kg of commercially available chromium powder (average particle size 150 μm) with a purity of 99.99% (4N) and the physical properties shown in Table 1 as the starting material.

[0199] The aforementioned chromium powder was filled into a soft iron can (400mm × 400mm × 200mm) at the filling density shown in Table 2 without heat treatment. After vacuum sealing, the filler was subjected to HIP treatment under the firing conditions shown in Table 2, thereby completing the firing process. The resulting HIP-treated body was then machined to obtain a chromium sintered body (ingot) with a diameter of 216mm × 6.35mm.

[0200] The evaluation results of the obtained chromium sintered bodies are shown in Table 2.

[0201] (Comparative Example 2)

[0202] Electrolytic chromium sheets with the properties shown in Table 1 were filled into a soft iron can without heat treatment at the filling density shown in Table 2. HIP treatment was performed under the firing conditions shown in Table 2. Otherwise, a chromium sintered body was made in the same manner as in Example 1.

[0203] (Comparative Example 3)

[0204] As raw material, metallic chromium sheets with the average particle size shown in Table 1 are used.

[0205] Next, the raw material is put into a melting furnace without preheating and heated to a temperature above 1950°C to melt it. After cooling, the melt is obtained.

[0206] Next, the melt was machined to obtain an ingot with a diameter of 216mm × 6.35mm.

[0207] Table 1 shows the heat treatment conditions and the properties of the starting materials; Table 2 shows the firing conditions and the evaluation results of the chromium sintered body; Table 3 shows the evaluation results of the target; and Table 4 shows the film-forming conditions and the evaluation results of the film-forming characteristics. It should be noted that in Comparative Examples 1 to 3, since the metallic chromium was not heat-treated, the "heating temperature" in Table 1 is indicated as "-". Additionally, in Table 2, "-" in Comparative Example 2 indicates that no measurement was performed. It should be noted that in Tables 1 and 2, "ppm" represents "mass ppm". Furthermore, in Comparative Example 3, the metallic chromium used as the raw material was melted instead of fired; therefore, the "firing conditions" in Table 2 are recorded as "melted product".

[0208] [Table 1]

[0209]

[0210] [Table 2]

[0211]

[0212] [Table 3]

[0213]

[0214] [Table 4]

[0215]

[0216] The results shown in Table 4 confirm that the chromium sintered bodies of Examples 1 and 2 can be used to manufacture sputtering targets that improve the uniformity of chromium film thickness when forming chromium films by sputtering, and have low oxygen content.

Claims

1. A chromium sintered body, characterized in that, Contains particles with an average KAM value of less than 2°. The average particle size is greater than 150 μm and less than 400 μm. The average aspect ratio of the particles is greater than 1 and less than 1.

8.

2. The chromium sintered body according to claim 1, wherein, The oxygen content is below 100 ppm by mass, and the relative density is above 99.6%.

3. The chromium sintered body according to claim 1 or 2, wherein, Its Vickers hardness is above 100 HV.

4. The chromium sintered body according to claim 1 or 2, wherein, The total content of metallic impurities is less than 100 ppm by mass.

5. The chromium sintered body according to claim 1 or 2, wherein, The average aspect ratio of the particles is greater than 1.0 and less than 1.

6.

6. The method for manufacturing the chromium sintered body according to claim 1, characterized in that, have: The heat treatment process includes heating the electrolytic chromium sheet at a temperature above 1200°C and below 1400°C; and The firing process involves filling the electrolytic chromium sheet into a container after the heat treatment process, and firing the resulting filler by hot isostatic pressing.

7. The method for manufacturing a chromium sintered body according to claim 6, wherein, The atmosphere for heat treatment is an inert gas atmosphere.

8. The method for manufacturing a chromium sintered body according to claim 6 or 7, wherein, The oxygen content of the electrolytic chromium sheet is below 130 ppm by mass.

9. A sputtering target comprising the chromium sintered body as described in claim 1 or 2.

10. A method for manufacturing a substrate with a chromium film, wherein, Using the sputtering target as described in claim 9, a substrate with a chromium film is manufactured by sputtering to form a chromium film on the substrate.

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