JP7735269B2 - Sputtering target and method of manufacturing the same - Google Patents

Description

This disclosure relates to a sputtering target suitable for forming protective films on mask blanks, which serve as the original masks used in extreme ultraviolet (EUV) lithography using EUV light, or pellicle films for preventing foreign matter from adhering to the mask pattern surface.

In semiconductor devices, there is a demand for miniaturization of the electronic circuits that make up the electronic component IC chips, and techniques such as EUV lithography are being used to form fine circuit patterns. However, defects such as minute dust particles or scratches on the order of a few nanometers that occur during manufacturing can become fatal defects in operation, so the material of the thin film used in the mask blanks, which are the original plates for the masks, is also important.

Thin films called blanks or pellicles for EUV applications are made using alloy materials with ruthenium added because of their superiority in transmitting or absorbing EUV light and in thermal conductivity, and the thin films are formed using the sputtering method.

As a sputtering target used in producing reflective mask blanks for EUV lithography, a sputtering target made of a ruthenium compound containing ruthenium and at least one element selected from niobium, molybdenum, zirconium, titanium, lanthanum, silicon, boron, and yttrium has been disclosed (see, for example, Patent Document 1). Patent Document 1 states that the content of niobium, molybdenum, zirconium, titanium, lanthanum, and silicon in the compound is preferably in the range of 3 to 75 atomic %, and that a range of 40 to 75 atomic % is desirable, particularly from the perspective of improving chemical resistance. Patent Document 1 also states that the content of boron and yttrium in the compound is preferably in the range of 3 to 50 atomic %, because these metals are easily oxidized and high contents of these metals may form an oxide layer on the surface of the deposited ruthenium compound film, resulting in degradation of optical properties (e.g., reflectivity of EUV light). Furthermore, Patent Document 1 describes that among impurities, the oxygen content is 2000 ppm or less, and the carbon content is 200 ppm or less, and that the low oxygen and carbon contents reduce particles generated from the target during film formation.

Japanese Patent Application Laid-Open No. 2006-283054

However, if particles that cause defects in the film are generated during film formation, they will adhere to the film, causing defects and reducing film yield. Since blanks are patterned on top to form the blueprints for semiconductors, particle adhesion to the film is an extremely serious issue. Pellicles also have a reduced ability to transmit EUV light in areas where particles adhere, which affects the transfer of circuits and reduces yield. There are many factors that cause particles to be generated during film formation, but particles originating from the target include arcing from voids due to poor density or arcing from oxides on the target surface.

Furthermore, in the case of blanks or pellicles, the thickness of the film formed is extremely thin and the area of the formed film is relatively wide, so the in-plane uniformity of the film thickness and composition within the film surface are important. Therefore, up until now, sputtering targets have required improvements in target density and reductions in oxygen content. However, with the recent formation of finer circuit patterns, the particles that cause defects have become even smaller, and it has become suspected that not only the particle sources mentioned above but also the materials added to ruthenium themselves are being dispersed during film formation.

To reduce oxygen content or improve density, sputtering targets have been manufactured using a melting method. However, ruthenium and its additive elements are generally high-melting materials with melting points exceeding 1600°C, making them difficult to melt. Furthermore, ruthenium and additive elements form various intermetallic compounds (IMCs), which are prone to cracking during the solidification process and can cause cracks during processing after melting and solidification, making target material difficult to form. Even if the target material can be formed, the IMCs precipitate and coarsen during solidification, degrading the composition distribution in the target's in-plane and cross-sectional directions (also known as the target thickness direction). This results in varying sputtering rates within the target and reduced uniformity in the in-plane composition and thickness distribution of the deposited film. While hot-working of target materials is common to refine the structure, hot-working is not possible due to the precipitation and coarsening of IMCs, which can lead to cracking or fracture problems.

Sintering methods can also be used to highly disperse additive elements within the target. The finer the additive element powder, the easier it is to disperse it within the target. However, handling fine powders is difficult when using highly reactive additive elements, as they can cause fires. Furthermore, even for stable additive elements, the finer the powder, the larger the specific surface area, making oxidation more likely to occur, resulting in a high oxygen content in the target. Therefore, relatively coarse-grained powders must be used, but achieving high dispersion requires high-energy mixing processes. However, preventing oxidation of additive elements requires extensive atmospheric control and can lead to the introduction of impurities (contamination) from the mixing medium, making this method unsuitable for EUV sputtering targets, which require high purity.

The object of this disclosure is to provide a sputtering target and a method for manufacturing the same that can obtain a uniform composition distribution in the in-plane direction and thickness direction of the deposited film.

As a result of extensive research to solve the above-mentioned problems, the inventors discovered that by setting the major axis of dispersed particles in a sputtering target to a predetermined particle diameter, it is possible to obtain a uniform composition distribution in the in-plane direction of the film and in the thickness direction of the film formed, and thus completed the present invention. Specifically, the sputtering target according to the present invention is a sputtering target of an alloy composed of ruthenium as a first element and one selected from boron, aluminum, titanium , zirconium , vanadium, niobium, chromium , and molybdenum as a second element, characterized in that the sputtering target contains dispersed particles composed of two phases including an intermetallic compound phase composed of the first element and the second element, and the maximum major axis of the dispersed particles is 500 μm or less. Setting the predetermined particle diameter allows for high dispersion in the sputtering target, thereby enabling a uniform composition distribution in the in-plane direction of the film and in the thickness direction of the film formed using the target.

In the sputtering target of the present invention, the two phases include (1) a combination of the intermetallic compound phase and a metallic ruthenium phase, which is the metallic phase of the first element; (2) a combination of two types of intermetallic compound phases; or (3) a combination of the intermetallic compound phase and a metallic phase of the second element.

The sputtering target according to the present invention is an alloy sputtering target comprising ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element, the sputtering target having dispersed particles containing an intermetallic compound phase consisting of two elements, the first element and the second element, the maximum major axis of the dispersed particles being 500 μm or less, and satisfying (Condition 1) or (Condition 2). the sputtering target has at least one location where the relative integrated intensity of the second peak in the sputtering in-plane direction of the sputtering target by X-ray diffraction is 60% or more of the relative integrated intensity of the first peak; the compositions of the sputtering target in the sputtering in-plane direction and the target thickness direction under (Condition 3) or (Condition 4) both differ by within ±1.5% from a reference composition; the reference composition is an average value of compositions measured at a total of 18 locations according to (Condition 3) or (Condition 4); and the crystallite size of the first peak is 400 Å or less .
(Condition 1)
Sputtering in-plane direction: The sputtering target is a disk-shaped target with a center O and a radius r, and the measurement locations are nine locations in total, on virtual cross lines that intersect at right angles with the center O as the intersection point, including one location at the center O, four locations at a distance of 0.45r from the center O, and four locations at a distance of 0.9r from the center O.
(Condition 2)
Sputtering in-plane direction: The sputtering target is a rectangle with a vertical length of L1 and a horizontal length of L2 (however, this includes a square where L1 and L2 are equal. Alternatively, the rectangle includes a rectangle formed by unfolding the side of a cylinder with length J and perimeter K, and in this form, L2 corresponds to the length J, L1 corresponds to the perimeter K, and the length J and the perimeter K have the relationship J>K, J=K, or J<K), and the measurement locations are virtual cross lines that intersect at right angles with the center of gravity O as the intersection point, and when the virtual cross lines are perpendicular to the sides of the rectangle, there are a total of nine measurement locations: one location at the center of gravity O, two locations on the virtual cross lines that are 0.25L1 vertically from the center of gravity O, two locations that are 0.25L2 horizontally from the center of gravity O, two locations that are 0.45L1 vertically from the center of gravity O, and two locations that are 0.45L2 horizontally from the center of gravity O.
By reducing the difference between the relative integrated intensity of the second peak and the relative integrated intensity of the first peak and lowering the degree of anisotropy of the structure, it is possible to suppress differences in sputtering rate during film formation and obtain a uniform film thickness.
The composition of the sputtering target in the sputtering in-plane direction and the target thickness direction under (Condition 3) or (Condition 4) both differs by within ±1.5% from a reference composition, and the reference composition is the average value of the compositions measured at a total of 18 locations according to (Condition 3) or (Condition 4). By suppressing deviation in the target composition, it is possible to suppress differences in the sputtering rate during film formation and to suppress deviations in the composition and film thickness of the film after film formation. In addition, it is possible to suppress the inclusion of particles caused by microprotrusions due to differences in the sputtering rate.
(Condition 3)
Sputtering in-plane direction: The sputtering target is a disk-shaped target with a center O and a radius r, and the measurement locations are nine locations in total, on virtual cross lines that intersect at right angles with the center O as the intersection point, including one location at the center O, four locations at a distance of 0.45r from the center O, and four locations at a distance of 0.9r from the center O.
Target thickness direction: A cross section passing through one of the imaginary cross lines is formed, and the cross section is a rectangle with a length of t (i.e., the thickness of the target is t) and a width of 2r. The measurement points are the center X on a vertical transverse line passing through the center O, three points in total (referred to as points a, X, and b) that are 0.45t above and below the center X, two points on the cross section that are 0.9r away from point a towards the left and right sides, two points in total that are 0.9r away from point X towards the left and right sides, and two points in total that are 0.9r away from point b towards the left and right sides, for a total of nine measurement points.
(Condition 4)
Sputtering in-plane direction: The sputtering target is a rectangle with a vertical length of L1 and a horizontal length of L2 (however, this includes a square where L1 and L2 are equal. Alternatively, the rectangle includes a rectangle formed by unfolding the side of a cylinder with length J and perimeter K, and in this form, L2 corresponds to the length J, L1 corresponds to the perimeter K, and the length J and the perimeter K have the relationship J>K, J=K, or J<K), and the measurement locations are virtual cross lines that intersect at right angles with the center of gravity O as the intersection point, and when the virtual cross lines are perpendicular to the sides of the rectangle, there are a total of nine measurement locations: one location at the center of gravity O, two locations on the virtual cross lines that are 0.25L1 vertically from the center of gravity O, two locations that are 0.25L2 horizontally from the center of gravity O, two locations that are 0.45L1 vertically from the center of gravity O, and two locations that are 0.45L2 horizontally from the center of gravity O.
Target thickness direction: A cross section is formed that passes through a line parallel to either the vertical side L1 or the horizontal side L2 of the imaginary cross line, and when one side is horizontal L2, the cross section is a rectangle with a vertical length of t (i.e., the thickness of the target is t) and a horizontal length of L2, and the measurement points are the center X on a vertical transverse line that passes through the center of gravity O, three points in total (referred to as point a, point X, and point b) that are 0.45t above and below the center X, two points on the cross section that are 0.45L2 away from point a towards the left and right sides, two points in total that are 0.45L2 away from point X towards the left and right sides, and two points in total that are 0.45L2 away from point b towards the left and right sides, for a total of nine measurement points.

In the sputtering target of the present invention, under (Condition 1) or (Condition 2), it is preferable that the relative integrated intensity of the second peak in the in-plane direction of the sputtering target be 60% or more of the relative integrated intensity of the first peak in 40% or more of the areas where this is the case. The presence of many areas where the difference between the relative integrated intensity of the second peak and the relative integrated intensity of the first peak is small reduces the degree of anisotropy in the structure, thereby suppressing differences in sputtering rate during film formation and achieving a uniform film thickness.

The sputtering target according to the present invention is an alloy sputtering target composed of ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element, characterized in that the sputtering target has dispersed particles containing an intermetallic compound phase composed of two elements, the first element and the second element, and the dispersed particles have a maximum major axis of 500 μm or less, and in (Condition 1) or (Condition 2), there is at least one location where the relative integrated intensity of the second peak measured by X-ray diffraction in the in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak, and in (Condition 1) or (Condition 2), there are 40% or more locations where the relative integrated intensity of the second peak measured by X-ray diffraction in the in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak, and the crystallite size of the first peak is 400 Å or less.

In the sputtering target of the present invention, it is preferable that the crystallite size of the first peak is 400 Å or less. By reducing the crystallite size, a homogeneous thin film can be formed.

In the sputtering target according to the present invention, it is preferable that the content of the second element is 3 to 70 atomic %. This improves the corrosion resistance of the composition of the deposited film while ensuring a reflectivity that satisfies the EUV standard.

The sputtering target according to the present invention preferably has an oxygen content of 500 ppm or less. This prevents oxygen from bonding with the second element to form an oxide of the second element within the sputtering target, thereby suppressing abnormal discharge caused by the oxide of the second element and thereby suppressing the generation of particles.

In the sputtering target according to the present invention, the carbon content is preferably 200 ppm or less. This prevents carbon from bonding with the second element to form carbides of the second element within the sputtering target, thereby suppressing abnormal discharge caused by carbides of the second element and thereby suppressing the generation of particles.

The method for manufacturing a sputtering target according to the present invention includes the steps of: preparing a raw material in which the first element and the second element are present in a predetermined element ratio; atomizing the raw material in a vacuum atmosphere of 1×10 ⁻² Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, to obtain an alloy powder by atomizing the raw material; and sintering the alloy powder by hot pressing (HP), spark plasma sintering (SPS), or hot isostatic pressing (HIP) in a vacuum atmosphere of 50 Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, to obtain a sintered body; and the alloy powder obtained by the atomizing method has a maximum major axis of 500 μm or less. Since the additive elements can be dispersed in the sputtering target while suppressing oxidation or carbonization, the composition of the film formed using the target can have a uniform composition distribution in the in-plane direction and in the film thickness direction while suppressing the inclusion of particles.

The method for manufacturing a sputtering target according to the present invention preferably further includes a classification step between the atomization step and the sintering step, in which particles with a maximum major axis exceeding 500 μm are removed from the alloy powder obtained by the atomization method. Because a high-density sputtering target can be formed in the step of obtaining a sintered body, the composition of the film formed using the target can have a uniform composition distribution in both the in-plane direction and the thickness direction of the film.

The present disclosure provides a sputtering target and a method for manufacturing the same that can achieve a uniform composition distribution in the formed film both in the in-plane direction and in the thickness direction of the film.

FIG. 2 is a schematic diagram showing measurement points in the in-plane direction of the disk-shaped target for sputtering. 1 is a schematic diagram showing measurement points in the target thickness direction of a disk-shaped target shown in the B-B cross section. FIG. FIG. 1 is a schematic diagram showing measurement points in the in-plane direction of a square plate-shaped target for sputtering. FIG. 1 is a schematic diagram showing measurement points in the target thickness direction of a square plate-shaped target shown in the CC cross section. FIG. 1 is a conceptual diagram for explaining measurement points on a cylindrical target.

The present invention will be described in detail below with reference to exemplary embodiments, but the present invention should not be construed as being limited to these descriptions. Various modifications to the exemplary embodiments may be made as long as the effects of the present invention are achieved.

The sputtering target according to this embodiment is an alloy sputtering target composed of ruthenium as a first element and one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element. The sputtering target has dispersed particles composed of two phases including an intermetallic compound phase composed of the first element and the second element, and the maximum major axis of the dispersed particles is 500 μm or less. For example, when the sputtering target is a sintered body, the dispersed particles present in the sputtering target correspond to the constituent particles of the sintered body. The dispersed particles have a plurality of crystal grains.

The maximum diameter of the dispersed particles is 500 μm or less, preferably 250 μm or less, more preferably 200 μm or less, and even more preferably 150 μm or less. If the maximum diameter of the dispersed particles is greater than 500 μm, the dispersed particles will be unevenly distributed within the sputtering target, resulting in compositional variations depending on the location on the sputtering target. If a sputtering target with compositional variations is used to form a film, compositional variations will occur in the in-plane direction and in the thickness direction of the film. Therefore, it is preferable to set the maximum diameter of the dispersed particles to 500 μm or less. Setting the maximum diameter to 500 μm or less means that no particles with a diameter exceeding 500 μm are included. The maximum diameter is determined by measuring the distance from one end of the largest dispersed particle to the other end of an SEM image within a 1200 μm x 1500 μm area, based on the image scale.

In the sputtering target according to this embodiment, the two-phase structure includes (1) a combination of an intermetallic compound phase and a metallic ruthenium phase, which is the metallic phase of the first element; (2) a combination of two types of intermetallic compound phases; or (3) a combination of an intermetallic compound phase and a metallic phase of the second element. In this embodiment, the number of phases is determined by the phases identified by X-ray diffraction. Furthermore, intermetallic compounds formed at grain boundaries are not included in the two-phase structure. The dispersed particles have two types of crystal grains corresponding to the two phases.

Grain boundaries include the boundary between a dispersed particle and its neighboring dispersed particle, and the boundary between a crystal grain and its neighboring crystal grain.

Taking the case where there are three types of intermetallic compounds, _Ru2AE , RuAE, and _RuAE2 , as an example, the following will be explained: "the two phases are (1) a combination of an intermetallic compound phase and a metallic ruthenium phase, which is a metal phase of the first element,""the two phases are (2) a combination of two types of intermetallic compound phases," and "the two phases are (3) a combination of an intermetallic compound phase and a metal phase of the second element." In this case, the morphologies of the phases that appear include a metallic ruthenium phase only (including a solid solution of ruthenium with a second element), a Ru phase (including a solid solution of ruthenium with a second element) and any one of the Ru ₂ AE phase, RuAE phase, and RuAE ₂ phase, a Ru ₂ AE phase only, a Ru ₂ AE phase and RuAE phase, a Ru ₂ AE phase and RuAE ₂ phase, a RuAE phase only, a RuAE phase and RuAE ₂ phase, a RuAE _{2 phase only, a RuAE 2 phase} , a RuAE phase, and Ru ₂ The AE phases include a combination of any one of the AE phases and the AE phase (including a solid solution of ruthenium in the second element), and a combination of only the metal phase of the second element (including a solid solution of ruthenium in the second element). Of these, "the two phases are (1) a combination of an intermetallic compound phase and a metallic ruthenium phase, which is the metal phase of the first element" refers to a combination of an Ru phase and any one of the _Ru2AE phase, RuAE phase, and _RuAE2 phase. Furthermore, "the two phases are (2) a combination of two types of intermetallic compound phases" refers to a combination of the _Ru2AE phase and the RuAE phase, a combination of the _Ru2AE phase and the _RuAE2 phase, or a combination of the RuAE phase and the _RuAE2 phase. Furthermore, "the two phases are a combination of (3) an intermetallic compound phase and a metal phase of a second element" means a combination of any one of the RuAE2 _phase , RuAE phase, and _Ru2AE phase and an AE phase. Cases in which there are two or four or more types of intermetallic compounds can be classified in the same way.

The two phases appear due to two types of crystal grains with different compositions in the dispersed particles. An example will be described using three types of intermetallic compounds: _Ru2AE , RuAE, and _RuAE2 . When "the two phases are (1) a combination of an intermetallic compound phase and a metallic ruthenium phase, which is the metallic phase of the first element," crystal grains of the Ru phase and crystal grains of any one of the _Ru2AE phase, RuAE phase, and RuAE2 _phase are present in the dispersed particles. Furthermore, "the two phases are (2) a combination of two types of intermetallic compound phases" refers to a form in which crystal grains of the _Ru2AE phase and crystal grains of the RuAE phase are present in the dispersed particles, a form in which crystal grains of the _Ru2AE phase and crystal grains of the _RuAE2 phase are present in the dispersed particles, or a form in which crystal grains of the RuAE phase and crystal grains of the _RuAE2 phase are present in the dispersed particles. Furthermore, "the two phases are a combination of (3) an intermetallic compound phase and a metal phase of the second element" means that crystal grains of any one of the RuAE2 _phase , RuAE phase, and _Ru2AE phase and crystal grains of the AE phase are present in the dispersed particles. Cases in which there are two or four or more types of intermetallic compounds can also be classified according to the same concept.

The sputtering target according to this embodiment is an alloy sputtering target composed of ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element, the sputtering target having dispersed particles containing an intermetallic compound phase composed of two elements, the first element and the second element, the maximum major axis of the dispersed particles being 500 μm or less, and (Condition 1) or (Condition 2), at least one location exists where the relative integrated intensity of the second peak by X-ray diffraction in the in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak. The first peak is the highest peak among the peaks derived from an alloy of the first element and the second element that appear in the CuKα, 2θ = 20 to 90° region in the X-ray diffraction spectrum. The second peak is the second highest peak among the peaks resulting from an alloy of the first element and the second element that appear in the CuKα, 2θ=20 to 90° region in the X-ray diffraction spectrum.
(Condition 1)
Sputtering in-plane direction: The sputtering target is a disk-shaped target with a center O and a radius r, and the measurement locations are nine locations in total, on virtual cross lines that intersect at right angles with the center O as the intersection point, including one location at the center O, four locations at a distance of 0.45r from the center O, and four locations at a distance of 0.9r from the center O.
(Condition 2)
Sputtering in-plane direction: The sputtering target is a rectangle with a vertical length of L1 and a horizontal length of L2 (however, this includes a square where L1 and L2 are equal. Alternatively, the rectangle includes a rectangle formed by unfolding the side of a cylinder with length J and perimeter K, and in this form, L2 corresponds to the length J, L1 corresponds to the perimeter K, and the length J and the perimeter K have the relationship J>K, J=K, or J<K), and the measurement locations are virtual cross lines that intersect at right angles with the center of gravity O as the intersection point, and when the virtual cross lines are perpendicular to the sides of the rectangle, there are a total of nine measurement locations: one location at the center of gravity O, two locations on the virtual cross lines that are 0.25L1 vertically from the center of gravity O, two locations that are 0.25L2 horizontally from the center of gravity O, two locations that are 0.45L1 vertically from the center of gravity O, and two locations that are 0.45L2 horizontally from the center of gravity O.

For X-ray diffraction, under (Condition 1) or (Condition 2), it is preferable that each of the nine measurement ranges be 10 mm x 10 mm. To determine whether the relative integrated intensity of the second peak obtained by X-ray diffraction in the in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak, the first and second peaks are separated based on the graph obtained by X-ray diffraction, and the relative integrated intensities of the first and second peaks are calculated using X-ray diffraction waveform analysis software, and it is determined whether the relative integrated intensity of the second peak is 60% or more of the relative integrated intensity of the first peak.

The relative integrated intensity of the second peak in the in-plane direction of the sputtering target by X-ray diffraction is 60% or more, preferably 65% or more, and more preferably 70% or more, of the relative integrated intensity of the first peak. In (Condition 1) or (Condition 2), if the relative integrated intensity of the second peak in X-ray diffraction is less than 60% of the relative integrated intensity of the first peak, variations in the thickness of the deposited film will occur. Therefore, it is preferable that the relative integrated intensity of the second peak in X-ray diffraction be 60% or more of the relative integrated intensity of the first peak.

In the sputtering target according to this embodiment, under (Condition 1) or (Condition 2), it is preferable that 40% or more, and more preferably 50% or more, of the sputtering target have a region where the relative integrated intensity of the second peak in the in-plane direction of the sputtering target's X-ray diffraction is 60% or more of the relative integrated intensity of the first peak. The presence of many regions where the difference between the relative integrated intensity of the second peak and the relative integrated intensity of the first peak is small reduces the degree of anisotropy in the structure, thereby suppressing differences in sputtering rate during film formation and achieving a uniform film thickness. In (Condition 1) or (Condition 2), "there are 40% or more of the locations where the relative integrated intensity of the second peak by X-ray diffraction in the sputtering in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak" means that, out of the nine measurement locations in (Condition 1) or (Condition 2), "there are 40% or more of the locations where the relative integrated intensity of the second peak by X-ray diffraction in the sputtering in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak" and "there are 9 measurement locations where the relative integrated intensity of the second peak by X-ray diffraction in the sputtering in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak" If there are four or more "locations where the relative integrated intensity of the second peak due to X-ray diffraction in the sputtering in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak" out of nine locations, then "40% or more of the locations where the relative integrated intensity of the second peak due to X-ray diffraction in the sputtering in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak" is satisfied.

In the sputtering target according to this embodiment, the composition of the sputtering target in the in-plane direction and the target thickness direction under (Condition 3) or (Condition 4) is preferably within ±1.5% of a reference composition, and the reference composition is preferably the average value of the compositions measured at a total of 18 locations according to (Condition 3) or (Condition 4).
(Condition 3)
Sputtering in-plane direction: The sputtering target is a disk-shaped target with a center O and a radius r, and the measurement locations are nine locations in total, on virtual cross lines that intersect at right angles with the center O as the intersection point, including one location at the center O, four locations at a distance of 0.45r from the center O, and four locations at a distance of 0.9r from the center O.
Target thickness direction: A cross section passing through one of the imaginary cross lines is formed, and the cross section is a rectangle with a length of t (i.e., the thickness of the target is t) and a width of 2r. The measurement points are the center X on a vertical transverse line passing through the center O, three points in total (referred to as points a, X, and b) that are 0.45t above and below the center X, two points on the cross section that are 0.9r away from point a towards the left and right sides, two points in total that are 0.9r away from point X towards the left and right sides, and two points in total that are 0.9r away from point b towards the left and right sides, for a total of nine measurement points.
(Condition 4)
Sputtering in-plane direction: The sputtering target is a rectangle with a vertical length of L1 and a horizontal length of L2 (however, this includes a square where L1 and L2 are equal. Alternatively, the rectangle includes a rectangle formed by unfolding the side of a cylinder with length J and perimeter K, and in this form, L2 corresponds to the length J, L1 corresponds to the perimeter K, and the length J and the perimeter K have the relationship J>K, J=K, or J<K), and the measurement locations are virtual cross lines that intersect at right angles with the center of gravity O as the intersection point, and when the virtual cross lines are perpendicular to the sides of the rectangle, there are a total of nine measurement locations: one location at the center of gravity O, two locations on the virtual cross lines that are 0.25L1 vertically from the center of gravity O, two locations that are 0.25L2 horizontally from the center of gravity O, two locations that are 0.45L1 vertically from the center of gravity O, and two locations that are 0.45L2 horizontally from the center of gravity O.
Target thickness direction: A cross section is formed that passes through a line parallel to either the vertical side L1 or the horizontal side L2 of the imaginary cross line, and when one side is horizontal L2, the cross section is a rectangle with a vertical length of t (i.e., the thickness of the target is t) and a horizontal length of L2, and the measurement points are the center X on a vertical transverse line that passes through the center of gravity O, three points in total (referred to as point a, point X, and point b) that are 0.45t above and below the center X, two points on the cross section that are 0.45L2 away from point a towards the left and right sides, two points in total that are 0.45L2 away from point X towards the left and right sides, and two points in total that are 0.45L2 away from point b towards the left and right sides, for a total of nine measurement points.

In the sputtering target according to this embodiment, the composition of the sputtering target in the sputtering plane direction and the target thickness direction under (Condition 3) or (Condition 4) preferably differs from the reference composition by within ±1.5%, more preferably within ±1.25%, and even more preferably within ±1%. The reference composition is the average value of the composition measured at a total of 18 locations according to (Condition 3) or (Condition 4). If the difference from the reference composition is greater than ±1.5%, there will be significant compositional variation depending on the location on the sputtering target. Therefore, if a film is formed using a sputtering target with such compositional variation, compositional variation will occur in the film's in-plane direction and thickness direction. Therefore, it is preferable that the composition of the sputtering target in the sputtering plane direction and the target thickness direction both differ by within ±1.5% from the reference composition.

In terms of composition, under (Condition 3) or (Condition 4), it is preferable that the measurement ranges at the nine points are each 700 μm x 900 μm.

Figure 1 is a schematic diagram showing measurement points (hereinafter simply referred to as measurement points) in the in-plane direction of the sputtering disk-shaped target. The measurement points in the in-plane direction of the sputtering targets under (Condition 1) and (Condition 3) will be explained with reference to Figure 1. For disk-shaped targets, the radius is preferably 25 to 225 mm, and more preferably 50 to 200 mm. The target thickness is preferably 3 to 30 mm, and more preferably 5 to 26 mm. This embodiment is expected to be more effective for larger targets.

In Figure 1, the sputtering target 200 is a disk-shaped target with a center O and a radius r. The measurement locations are nine locations on imaginary cross lines (L) that intersect at right angles with the center O as the intersection point: one location (S1) at the center O, four locations (S3, S5, S6, and S8) 0.45r away from the center O, and four locations (S2, S4, S7, and S9) 0.9r away from the center O.

Figure 2 is a schematic diagram showing the measurement points in the target thickness direction of the disk-shaped target shown in the B-B cross section of Figure 1. Referring to Figure 2, the measurement points in the target thickness direction of the sputtering target (Condition 3) will be explained.

In Figure 2, the B-B cross section of Figure 1 is a rectangle with a length of t (i.e., the thickness of the target is t) and a width of 2r. The measurement points are the center X (C1) on the vertical cross line passing through the center O shown in Figure 1, three points 0.45t above and below the center X (referred to as point a (C4), point X (C1), and point b (C5)), two points (C6, C7) on the cross section 0.9r away from point a towards the left and right sides, two points (C2, C3) 0.9r away from point X towards the left and right sides, and two points (C8, C9) 0.9r away from point b towards the left and right sides, for a total of nine measurement points.

Figure 3 is a schematic diagram showing measurement points in the in-plane direction of sputtering for a square plate-shaped target. The measurement points in the in-plane direction of sputtering for sputtering targets under (Condition 2) and (Condition 4) will be explained with reference to Figure 3. For rectangular or square targets, the vertical and horizontal lengths are preferably 50 to 450 mm, and more preferably 100 to 400 mm. The target thickness is preferably 3 to 30 mm, and more preferably 5 to 26 mm. This embodiment is expected to be more effective for larger targets.

Sputtering target 300 is a rectangular target (including squares where L1 and L2 are equal) with a vertical length of L1 and a horizontal length of L2. Figure 3 shows sputtering target 300 in a configuration where L1 = L2. Measurement locations are nine in total: one location (P1) at the center of gravity O, two locations (P6, P8) on the virtual crosshairs that are 0.25L1 vertically from the center of gravity O, two locations (P3, P5) that are 0.25L2 horizontally from the center of gravity O, two locations (P7, P9) that are 0.45L1 vertically from the center of gravity O, and two locations (P2, P4) that are 0.45L2 horizontally from the center of gravity O, forming an imaginary crosshair (Q) that intersects at right angles with the sides of the rectangle (or square). When the sputtering target is rectangular, L1 and L2 can be appropriately selected regardless of the length of the sides.

Figure 4 is a schematic diagram showing measurement points in the target thickness direction of a square plate-shaped target shown in the C-C cross section of Figure 3.With reference to Figure 4, the measurement points in the target thickness direction of the sputtering target (condition 4) will be explained.

In Figure 4, the C-C cross section of Figure 3 forms a cross section passing through a line parallel to the horizontal side, and the cross section is a rectangle with a length of t (i.e., the thickness of the target is t) and a width of L2. The measurement points are the center X on a vertical transverse line passing through the center of gravity O, three points in total 0.45t above and below the center X (referred to as point a (D4), point X (D1), and point b (D5)), two points on the cross section 0.45L2 away from point a towards the left and right sides (D6, D7), two points in total 0.45L2 away from point X towards the left and right sides (D2, D3), and two points 0.45L2 away from point b towards the left and right sides (D8, D9), for a total of nine measurement points.

(Cylindrical sputtering target)
FIG. 5 is a conceptual diagram illustrating the measurement location of a cylindrical target. When the sputtering target is cylindrical, the side surface of the cylinder is the sputtering surface, and the developed view is rectangular (including square). Therefore, (Condition 2) or (Condition 4) can be considered in the same manner as in FIGS. 3 and 4. The rectangle includes a rectangle obtained by developing the side surface of a cylinder with length J and perimeter K. In this form, L2 corresponds to length J, L1 corresponds to perimeter K, and the relationship between length J and perimeter K is J > K, J = K, or J < K. In FIG. 5, if the sputtering target 400 is cylindrical with a height (length) J and a perimeter of the barrel K, consider the E-E cross section and the D-D developed surface so that the cross section is at both ends. First, the measurement location in the target thickness direction is considered in the E-E cross section in the same manner as in FIG. 4. That is, the height J of the cylindrical material corresponds to L2 in FIG. 4, and the thickness of the cylindrical material corresponds to thickness t in FIG. 4, and these are the measurement locations. The measurement points in the sputtering in-plane direction are considered to be the same as those in FIG. 3 on the D-D expanded plane. That is, the measurement points are determined by considering that the height J of the cylindrical material corresponds to L2 in FIG. 3 and the circumferential length K of the cylindrical material's barrel corresponds to L1 in FIG. 3. In the case of a cylindrical target, the circumferential length of the cylindrical barrel is preferably 100 to 350 mm, more preferably 150 to 300 mm. The length of the cylinder is preferably 300 to 3000 mm, more preferably 500 to 2000 mm. The thickness of the target is preferably 3 to 30 mm, more preferably 5 to 26 mm. This embodiment is expected to be more effective for large targets.

In the sputtering target according to this embodiment, the crystallite size of the first peak is preferably 400 Å or less, more preferably 350 Å or less, and even more preferably 300 Å or less. If the crystallite size of the first peak is larger than 400 Å, the orientation of the crystallites will be biased, resulting in differences in sputtering rate and film thickness depending on the location, so it is preferable to set the crystallite size of the first peak to 400 Å or less. The crystallite size is measured using X-ray diffraction waveform analysis software.

The sputtering target according to this embodiment preferably has a second element content of 3 to 70 atomic %, more preferably 5 to 65 atomic %, and even more preferably 10 to 60 atomic %. If the content is less than 3 atomic %, improvement in the reflectivity of the film cannot be expected when a thin film is formed using the target. If the content is more than 70 atomic %, the chemical resistance will be reduced due to the small amount of ruthenium, making it difficult to use the film even when formed using the target. Therefore, a content of 3 to 70 atomic % is preferred.

The boron content is preferably 25 to 65 atomic percent, more preferably 30 to 60 atomic percent. The aluminum content is preferably 20 to 60 atomic percent, more preferably 30 to 55 atomic percent. The titanium content is preferably 10 to 65 atomic percent, more preferably 25 to 50 atomic percent. The zirconium content is preferably 15 to 65 atomic percent, more preferably 20 to 50 atomic percent. The hafnium content is preferably 15 to 65 atomic percent, more preferably 20 to 50 atomic percent. The vanadium content is preferably 35 to 65 atomic percent, more preferably 40 to 60 atomic percent. The niobium content is preferably 15 to 60 atomic percent, more preferably 20 to 50 atomic percent. The tantalum content is preferably 10 to 65 atomic percent, more preferably 25 to 40 atomic percent. The chromium content is preferably 30 to 65 atomic %, more preferably 40 to 60 atomic %, the molybdenum content is preferably 25 to 65 atomic %, more preferably 30 to 60 atomic %, and the tungsten content is preferably 10 to 65 atomic %, more preferably 15 to 60 atomic %.

The sputtering target according to this embodiment preferably has an oxygen content of 500 ppm or less, more preferably 400 ppm or less, and even more preferably 300 ppm or less. If the oxygen content is greater than 500 ppm, the added components in the target will combine with oxygen to form oxides. This can result in particles being mixed into the film when a thin film is formed using the target, or the sputtering rate will vary from location to location, resulting in uneven film thickness. Therefore, it is preferable to keep the oxygen content at 500 ppm or less.

The sputtering target according to this embodiment preferably has a carbon content of 200 ppm or less, more preferably 150 ppm or less, and even more preferably 100 ppm or less. If the carbon content is greater than 200 ppm, the carbon will bond with the additive components in the target to form carbides. This can result in particles being mixed into the film when a thin film is formed using the target, or the sputtering rate will vary from location to location, resulting in uneven film thickness. Therefore, it is preferable to keep the carbon content at 200 ppm or less.

The filling rate of the sputtering target according to this embodiment is preferably 80% or more, more preferably 95% or more, and even more preferably 98% or more. Increasing the filling rate allows for a sputtering target with fewer voids. When a film is formed using this sputtering target, particle contamination can be suppressed, and the sputtering rate is less likely to vary from location to location, allowing for the formation of a thin film with minimal variation in film thickness and composition. In this embodiment, a sputtering target with such a high filling rate can be achieved by setting the maximum major axis of the dispersed particles to 500 μm or less.

The method for manufacturing a sputtering target according to this embodiment will be described. The method for manufacturing a sputtering target according to this embodiment is a method for manufacturing a sputtering target of an alloy composed of ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element, and includes the steps of: preparing a raw material in which the first element and the second element are in a predetermined element ratio (first step) ^; The method includes an atomization step (second step) in which the raw materials are used to obtain alloy powder by atomization in a vacuum atmosphere of 50 Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol% or less of hydrogen gas; and a sintering step (third step) in which the alloy powder is sintered by hot pressing (HP), spark plasma sintering (SPS), or hot isostatic pressing (HIP) in a vacuum atmosphere of 50 Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, to obtain a sintered body, wherein the alloy powder obtained by the atomization method has a maximum major axis of 500 μm or less.

[First step (preparation step)]
This step is a step of preparing the raw material (hereinafter also simply referred to as the "raw material") used when producing the alloy powder of the first element and the second element in the second step. The raw material is a raw material for a ruthenium-boron alloy, a raw material for a ruthenium-aluminum alloy, a raw material for a ruthenium-titanium alloy, a raw material for a ruthenium-zirconium alloy, a raw material for a ruthenium-hafnium alloy, a raw material for a ruthenium-vanadium alloy, a raw material for a ruthenium-niobium alloy, a raw material for a ruthenium-tantalum alloy, a raw material for a ruthenium-chromium alloy, a raw material for a ruthenium-molybdenum alloy, or a raw material for a ruthenium-tungsten alloy. The raw materials for producing the powder prepared in the first step can be exemplified by (1A) preparing the individual metals of the constituent elements of the alloy target as starting raw materials and mixing them to form the raw material, (2A) preparing an alloy of the same composition as the alloy target as the starting raw material and using this as the raw material, or (3A) preparing an alloy of the same or partially missing constituent elements as the alloy target as the starting raw material, whose composition ratio deviates from the desired composition ratio, and mixing these with the individual metals to adjust to the desired composition to form the raw material. As the starting raw materials, ruthenium and boron, ruthenium and aluminum, ruthenium and titanium, ruthenium and zirconium, ruthenium and hafnium, ruthenium and vanadium, ruthenium and niobium, ruthenium and tantalum, ruthenium and chromium, ruthenium and molybdenum, or ruthenium and tungsten are introduced into a melting device and melted to produce the raw material. It is preferable to use materials with low impurities for the melting device and containers to prevent large amounts of impurities from being mixed into the raw material after melting. The melting method should be selected according to the following melting temperatures: 1400 to 2400°C for ruthenium-boron alloy raw materials, 1600 to 2400°C for ruthenium-aluminum alloy raw materials, 1700 to 2400°C for ruthenium-titanium alloy raw materials, 1700 to 2400°C for ruthenium-zirconium alloy raw materials, 2000 to 2500°C for ruthenium-hafnium alloy raw materials, 1700 to 2400°C for ruthenium-zirconium alloy raw materials, 2000 to 2500°C for ruthenium-zirconium ...1700 to 2400°C for ruthenium-zirconium alloy raw materials, 1700 to 2400°C for ruthenium-zirconium alloy raw materials, 1700 to 2400°C for ruthenium-zirconium alloy raw materials, 1700 to 2400°C for ruthenium-zirconium alloy raw materials, 1700 to 2400°C for The raw materials for the ruthenium-vanadium alloy, the raw materials for the ruthenium-niobium alloy at 1600 to 2400° C., the raw materials for the ruthenium-tantalum alloy at 1900 to 2800° C., the raw materials for the ruthenium-chromium alloy at 1600 to 2400° C., the raw materials for the ruthenium-molybdenum alloy at 1900 to 2400° C., or the raw materials for the ruthenium-tungsten alloy at 2200 to 2900° C. The atmosphere inside the melting apparatus may be a vacuum atmosphere with a degree of vacuum of 1×10 ⁻² Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol % or less of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol % or less of hydrogen gas.

In addition to the three raw material forms described above in (1A), (2A), and (3A), the alloy powder raw material may be in the form of alloy grains or alloy ingots, or a combination of powder, grains, and ingots. Powder, grains, and ingots represent different particle sizes, but there are no particular restrictions on the particle size as long as they can be used in the powder manufacturing equipment used in the second step. Specifically, since the raw materials are melted within the powder manufacturing equipment used in the second step, there are no particular restrictions on the size of the raw materials as long as they can be fed into the powder manufacturing equipment.

[Second process (atomization process)]
This step is a step of producing an alloy powder of a first element and a second element. The alloy powder of the first element and the second element is a ruthenium-boron alloy powder, a ruthenium-aluminum alloy powder, a ruthenium-titanium alloy powder, a ruthenium-zirconium alloy powder, a ruthenium-hafnium alloy powder, a ruthenium-vanadium alloy powder, a ruthenium-niobium alloy powder, a ruthenium-tantalum alloy powder, a ruthenium-chromium alloy powder, a ruthenium-molybdenum alloy powder, or a ruthenium-tungsten alloy powder. The raw materials produced in the first step are charged into a powder production apparatus and melted to form a molten metal. Then, a gas is blown into the molten metal, causing it to scatter and rapidly solidify, producing a powder. It is preferable to use materials with low impurities for the equipment and container used in the powder production apparatus so that a large amount of impurities are not mixed into the alloy powder of the first element and the second element after melting. As a melting method, a method capable of handling the following melting temperatures is selected. The melting temperatures are 1400 to 2400°C for ruthenium-boron alloy raw materials, 1600 to 2400°C for ruthenium-aluminum alloy raw materials, 1700 to 2400°C for ruthenium-titanium alloy raw materials, 1700 to 2400°C for ruthenium-zirconium alloy raw materials, 2000 to 2500°C for ruthenium-hafnium alloy raw materials, and 1700 to 2400°C for ruthenium-zirconium alloy raw materials. The raw materials for the ruthenium-vanadium alloy, the raw materials for the ruthenium-niobium alloy at 1600 to 2400° C., the raw materials for the ruthenium-tantalum alloy at 1900 to 2800° C., the raw materials for the ruthenium-chromium alloy at 1600 to 2400° C., the raw materials for the ruthenium-molybdenum alloy at 1900 to 2400° C., or the raw materials for the ruthenium-tungsten alloy at 2200 to 2900° C. The atmosphere inside the powder manufacturing equipment is a vacuum atmosphere with a degree of vacuum of 1×10 ⁻² Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol% or less of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol% or less of hydrogen gas. The temperature of the molten metal during spraying is preferably "at least 100°C above the melting point of the first and second elements, depending on the type of alloy." It is more preferable to spray at "at least 150 to 250°C above the melting point of the first and second elements, depending on the type of alloy." If the temperature is too high, cooling during granulation is insufficient, making it difficult to obtain powder and resulting in poor production efficiency. If the temperature is too low, nozzle clogging during spraying is likely to occur. Gases used during spraying include, but are not limited to, nitrogen and argon. In the case of alloy powder, the precipitated particle size corresponding to the islands in a sea-island structure may be small. This state is already achieved in the alloy powder stage and is maintained even after sintering or when the target is formed. Therefore, by producing alloy powder through this process, the generation of phases containing a large amount of additives, which occurs when a sputtering target is produced by a melting method, can be suppressed. When a sputtering target is produced using the alloy powder produced through this process and a film is formed, the difference in sputtering rate from other locations can be suppressed. The quenched powder has the same element ratio of the first element to the second element as the raw material prepared in the first step. In this case, the maximum major axis of the powder obtained by the atomization method is 500 μm or less, preferably 400 μm or less, and more preferably 300 μm or less. If the maximum major axis of the powder is greater than 500 μm, the density will be insufficient even after sintering in the third step, and when a thin film is formed using the target, particles will be mixed in, resulting in uneven film thickness. Therefore, it is preferable to set the maximum major axis of the powder to 500 μm or less. Here, setting the maximum major axis to 500 μm or less means that the powder does not contain particles with a major axis exceeding 500 μm.

The method for manufacturing a sputtering target according to this embodiment preferably further includes a classification step between the atomization step and the sintering step to remove particles with a maximum major axis exceeding 500 μm from the alloy powder obtained by the atomization method. By adjusting the particle size through classification, a sputtering target with higher density can be formed in the step of obtaining a sintered body, and the composition of the film formed using this target can have a uniform composition distribution in both the in-plane direction and the thickness direction of the film.

[Third step (sintering step)]
This step is a step of obtaining a sintered body that will become a target from the powder obtained in the second step. Sintering is performed by hot pressing (HP), spark plasma sintering (SPS), or hot isostatic pressing (HIP). Sintering is performed using the alloy powder of the first element and the second element obtained in the second step or the alloy powder classified in the classification step. It is preferable to pack any of the powders listed above into a mold, seal the powder with a mold and punch, etc., using a preliminary pressure of 10 to 30 MPa, and then sinter. In this case, the sintering temperature is preferably 1100 to 2000°C, and the applied pressure is preferably 40 to 196 MPa. The sintering temperature is 1150 to 1300°C for ruthenium-boron alloy powder, 1150 to 1500°C for ruthenium-aluminum alloy powder, 1150 to 1600°C for ruthenium-titanium alloy powder, 1150 to 1300°C for ruthenium-zirconium alloy powder, 1250 to 1400°C for ruthenium-hafnium alloy powder, and 1250 to 1400°C for ruthenium-vanadium alloy powder. For ruthenium-niobium alloy powder, the temperature is 1250 to 1400°C, for ruthenium-tantalum alloy powder, 1400 to 1800°C, for ruthenium-chromium alloy powder, 1100 to 1250°C, for ruthenium-molybdenum alloy powder, or more preferably, 1400 to 1800°C, or for ruthenium-tungsten alloy powder, the temperature is 1500 to 2000°C. The atmosphere inside the sintering apparatus may be a vacuum atmosphere with a degree of vacuum of 50 Pa or less, a nitrogen gas atmosphere containing 4 vol% or less of hydrogen gas, or an inert gas atmosphere containing 4 vol% or less of hydrogen gas. The hydrogen gas content is preferably 0.1 vol% or more.

By going through at least steps 1 to 3, it is possible to reduce compositional deviations in the in-plane direction and thickness direction of the sputtering target, and to produce a sputtering target with a low content of impurities that affect thin film formation.

In this embodiment, the method of composition analysis under (Condition 3) or (Condition 4) may be energy dispersive X-ray spectroscopy (EDS), inductively coupled plasma optical emission spectroscopy (ICP), or X-ray fluorescence spectroscopy (XRF), but composition analysis by EDS is preferred.

The present invention will be explained in more detail below with reference to examples, but the present invention should not be construed as being limited to these examples.

Example 1
A 3N5up purity Ru raw material and a 3N purity Nb raw material were placed in a powder manufacturing apparatus, and the inside of the powder manufacturing apparatus was adjusted to a vacuum atmosphere of 5 × 10 ^-3 Pa or less. The Ru raw material and the Nb raw material were melted at a melting temperature of 1900 ° C to form a molten metal. Argon gas was then sprayed onto the molten metal, causing the molten metal to scatter and rapidly solidify. Ru-20 atomic % Nb powder (in this case, Ru is 80 atomic % Ru, but the atomic percentage of Ru is omitted. The same applies hereinafter) having a maximum diameter of 500 μm or less was produced. Here, the Ru-20 atomic % Nb powder having a maximum diameter of 500 μm or less was adjusted by classification. The Ru-20 atomic % Nb powder was then filled into a carbon mold for spark plasma sintering (hereinafter also referred to as SPS sintering). Next, the alloy powder was sealed using a mold and punch under a preliminary pressure of 30 MPa, and the mold filled with the alloy powder was placed in an SPS apparatus (model number: SPS-825, manufactured by SPS Syntex Co., Ltd.). Sintering was carried out under the following conditions: a sintering temperature of 1250°C, a pressure of 55 MPa, and a vacuum atmosphere of 20 Pa or less inside the sintering apparatus. The Ru-20 atomic % Nb sintered body was processed using a grinding machine, lathe, etc. to produce a Φ50.8 mm x 5 mmt Ru-20 atomic % Nb target of Example 1.

(Comparative Example 1)
In Example 1, instead of spraying argon gas onto the molten metal, scattering the molten metal, and rapidly solidifying it to produce Ru-20 atomic % Nb powder with a maximum diameter of 500 μm or less, argon gas was sprayed onto the molten metal, scattering the molten metal, and rapidly solidifying it to produce Ru-20 atomic % Nb powder with a maximum diameter of more than 500 μm. Except for this, a Ru-20 atomic % Nb sintered body was obtained in the same manner as in Example 1. Here, the Ru-20 atomic % Nb powder with a maximum diameter of more than 500 μm was adjusted by classification. An attempt was made to process the Ru-20 atomic % Nb sintered body using a grinding machine, but chips occurred on the outer periphery of the plate during grinding, and cracks occurred in the plate starting from the chips, making it impossible to produce a sputtering target.

(Comparative Example 2)
Pure Ru powder with a particle size of 100 μm or less and a purity of 3N5 up was used, and Nb powder with a particle size of 100 μm or less and a purity of 3N5 up was used, and the amounts of each powder were adjusted to obtain Ru-20 atomic % Nb, and then mixed. Thereafter, a Ru-20 atomic % Nb sintered body was produced in the same manner as in the examples. The sintered Ru-20 atomic % Nb sintered body was processed using a grinding machine, lathe, etc., to produce a Φ50.8 mm x 5 mmt Ru-20 atomic % Nb target of Comparative Example 2.

(Comparative Example 3)
A 3N5up purity Ru raw material and a 3N purity Nb raw material were weighed to give Ru-20 atomic % Nb, and melted in an arc melting apparatus (AME-300 model, manufactured by ULVAC) to obtain a melted plate of approximately 60 mm square x 6 mm. Next, an attempt was made to machine this plate to produce a sputtering target of Φ50.8 mm x 5 mmt, but grinding caused chipping on the outer periphery of the plate, and cutting by wire electric discharge machining caused cracks in the plate, making it impossible to produce a sputtering target.

(Maximum major axis of dispersed particles observed by SEM)
For the targets of Example 1, Comparative Example 1, and Comparative Example 2, the major axis of the dispersed particles was measured by direct observation in a 1200 μm × 1500 μm SEM image using an electron microscope (model number JSM-6010: manufactured by JEOL). The measurement results are shown in Table 1. As a result of the observation, the maximum major axis of the dispersed particles in Example 1 was 250 μm, and it was confirmed that the dispersed particles were dispersed in the sputtering target. On the other hand, the maximum major axis of the dispersed particles in Comparative Example 1 was 984 μm. The maximum major axis of the dispersed particles in Comparative Example 2 was 80 μm.

(Content survey by EDS)
For the targets of Example 1 and Comparative Example 2, compositional analysis was performed by energy dispersive X-ray spectroscopy (EDS) to measure the Nb content of S1 to S9 in FIG. 1 and the Nb content of C1 to C9 in FIG. 2 . The measurement range was 700 μm × 900 μm. The measurement results are shown in Tables 2 to 5. From Table 2, the average Nb content of S1 to S9 in Example 1 was 19.95%, and the difference between the Nb content of each point S1 to S9 and the average Nb content of S1 to S9 in Example 1 was a maximum of 0.41 and a minimum of 0.03. From Table 2, the average Nb content of C1 to C9 in Example 1 was 20.04%, and the difference between the Nb content of each point C1 to C9 and the average Nb content of C1 to C9 in Example 1 was a maximum of 0.52 and a minimum of 0.03. The target of Example 1 had small variations in composition due to differences in location in both the in-plane direction of sputtering and the thickness direction of the target. Furthermore, as shown in Table 3, the average Nb content of S1 to S9 and C1 to C9 in Example 1 was 19.99%, and the difference between the Nb content at each point of S1 to S9 and C1 to C9 and the average value of the Nb content of S1 to S9 and C1 to C9 in Example 1 was a maximum of 0.47 and a minimum of 0.00. The target of Example 1 had small variations in composition at each point, i.e., the variations in composition due to differences in location in the in-plane direction and thickness direction of the target were small. On the other hand, from Table 4, the average value of the Nb content of S1 to S9 in Comparative Example 2 was 20.00%, and the difference between the Nb content of each point S1 to S9 and the average value of the Nb content of S1 to S9 was a maximum of 0.98 and a minimum of 0.25 in Comparative Example 2. From Table 4, the average value of the Nb content of C1 to C9 in Comparative Example 2 was 20.24%, and the difference between the Nb content of each point C1 to C9 and the average value of the Nb content of C1 to C9 was a maximum of 1.03 and a minimum of 0.06 in Comparative Example 2. The target of Comparative Example 2 had small deviations in composition due to location in both the sputtering in-plane direction and the target thickness direction. Furthermore, from Table 5, the average value of the Nb content of S1 to S9 and C1 to C9 in Comparative Example 2 was 20.12%, and the difference between the Nb content of each point of S1 to S9 and C1 to C9 and the average value of the Nb content of S1 to S9 and C1 to C9 was a maximum of 1.10 and a minimum of 0.18 in Comparative Example 2. The target of Comparative Example 2 had small deviations in composition at each point, that is, the deviations in composition due to differences in location in the in-plane direction and thickness direction of the target were small.

(XRD peak intensity)
X-ray diffraction was performed on the targets of Example 1 and Comparative Example 2 at positions S1 to S9 under Condition 1. The relative integrated intensity of the first peak and the relative integrated intensity of the second peak derived from the Ru-20 atomic % Nb alloy were compared over the CuKα, 2θ = 20 to 90° range, and the ratio of the relative integrated intensity of the second peak to the relative integrated intensity of the first peak was calculated. The calculation results are shown in Table 6. From the results in Table 6, in Example 1, the ratio of the relative integrated intensity of the second peak to the relative integrated intensity of the first peak was high, ranging from 81.8% to 84.9%, and therefore the relative integrated intensity of the second peak was 60% or more of the relative integrated intensity of the first peak at all positions S1 to S9 under Condition 1, confirming that the sputtering target of Example 1 has a low degree of anisotropy. The composition of the film deposited using this target was able to obtain a uniform composition distribution in both the in-plane direction and the thickness direction of the film. On the other hand, in Comparative Example 2, the ratio of the relative integrated intensity of the second peak to the relative integrated intensity of the first peak was low at 38.4% to 52.6%, and therefore the relative integrated intensity of the second peak was lower than 60% of the relative integrated intensity of the first peak at all points S1 to S9 of (Condition 1), confirming that the sputtering target of Comparative Example 2 had a strong orientation in the (101) direction and a high degree of anisotropy. When a thin film was formed using this target, the sputtering rate varied depending on the point, resulting in variations in film thickness.

(oxygen and carbon content)
The oxygen and carbon contents of the targets of Example 1 and Comparative Example 2 were measured using a mass spectrometer (model number: Element GD, manufactured by Thermo Fisher Scientific). The measurement results are shown in Table 7. The oxygen content of Example 1 was 43 ppm, and the carbon content was 9 ppm, indicating low oxygen and carbon contents. Therefore, the additive elements could be dispersed in the sputtering target while suppressing oxidation and carbonization, and the film formed using this target had a uniform composition distribution in both the in-plane direction and the film thickness direction. Furthermore, particle contamination could be reduced, thereby suppressing film thickness variation. On the other hand, the oxygen content of Comparative Example 2 was 695 ppm, and the carbon content was 13 ppm, indicating a high oxygen content. For this reason, when the target is heated during film formation, the additive components in the target combine with oxygen to form oxides, and when a thin film is formed using the target, the sputtering rate varies from place to place, resulting in variations in film thickness.

(filling rate)
The packing fractions of the targets of Example 1, Comparative Example 1, and Comparative Example 2 were calculated using the Archimedes method. The calculation results are shown in Table 8. The calculation method was to divide (the actual density of the sintered body measured by the Archimedes method) by (the theoretical density of the sintered body), and then multiply this by 100 to convert to a percentage, to obtain the packing fraction. The packing fraction of Example 1 was 99.7%, and a sputtering target with a high packing fraction and few voids was obtained. In contrast, the packing fraction of Comparative Example 1 was 75.2%, and a sputtering target with a low packing fraction and many voids was obtained. The packing fraction of Comparative Example 2 was 99.9%, and a sputtering target with a high packing fraction and few voids was obtained.

The results of Example 1 and Comparative Examples 1 to 3 show that in Example 1, the maximum diameter of the dispersed particles, compositional deviation, ratio of the relative integrated intensity of the second peak to the relative integrated intensity of the first peak, oxygen content, carbon content, and packing ratio were all satisfactory. Therefore, a thin film with minimal variation in the target Nb concentration was formed. Furthermore, particle contamination was suppressed, and the sputtering rate was minimally varied from location to location, resulting in the formation of a thin film with minimal variation in film thickness and composition. Because the additive elements could be dispersed in the sputtering target while suppressing oxidation and carbonization, particle contamination into the film was suppressed when this target was used for film formation. Furthermore, the film formed using this target achieved a uniform composition distribution in both the in-plane and thickness directions. Furthermore, the film formed using this target achieved a uniform film thickness. On the other hand, in Comparative Example 1, the dispersed particles had a large diameter and a low packing ratio, which resulted in cracks occurring during the grinding process, making it impossible to produce a film. In Comparative Example 2, the ratio of the relative integrated intensity of the second peak to the relative integrated intensity of the first peak was small, and the oxygen content was high, so when a film was formed using the sputtering target, the film thickness varied. In Comparative Example 3, the dissolved ruthenium was too hard, so cracks occurred during grinding and cutting, making it impossible to produce a film.

200, 300, 400 Sputtering target O Center, center of gravity L, Q Virtual cross lines S1 to S9 Measurement points in the sputtering in-plane direction C1 to C9 Measurement points in the target thickness direction P1 to P9 Measurement points in the sputtering in-plane direction D1 to D9 Measurement points in the target thickness direction

Claims (10)

A sputtering target of an alloy comprising ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, vanadium , niobium, chromium , and molybdenum as a second element,
the sputtering target has dispersed particles composed of two phases including an intermetallic compound phase composed of two elements, the first element and the second element,
A sputtering target characterized in that the dispersed particles have a maximum major axis of 500 μm or less. The sputtering target of claim 1, characterized in that the two phases are (1) a combination of the intermetallic compound phase and a metallic ruthenium phase, which is the metallic phase of the first element, (2) a combination of two types of the intermetallic compound phases, or (3) a combination of the intermetallic compound phase and a metallic phase of the second element. A sputtering target of an alloy comprising ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element,
the sputtering target has dispersed particles containing an intermetallic compound phase consisting of two elements, the first element and the second element,
The dispersed particles have a maximum major axis of 500 μm or less,
In (Condition 1) or (Condition 2), there is at least one location where the relative integrated intensity of the second peak in the in-plane direction of the sputtering target by X-ray diffraction is 60% or more of the relative integrated intensity of the first peak,
The composition of the sputtering target in the in-plane direction and the thickness direction of the target under (Condition 3) or (Condition 4) is within ±1.5% of a reference composition, and the reference composition is an average value of the compositions measured at a total of 18 locations under (Condition 3) or (Condition 4),
A sputtering target characterized in that the crystallite size of the first peak is 400 Å or less .
(Condition 1)
Sputtering in-plane direction: The sputtering target is a disk-shaped target with a center O and a radius r, and the measurement locations are nine locations in total, on virtual cross lines that intersect at right angles with the center O as the intersection point, including one location at the center O, four locations at a distance of 0.45r from the center O, and four locations at a distance of 0.9r from the center O.
(Condition 2)
Sputtering in-plane direction: The sputtering target is a rectangle with a vertical length of L1 and a horizontal length of L2 (however, this includes a square where L1 and L2 are equal. Alternatively, the rectangle includes a rectangle formed by unfolding the side of a cylinder with length J and perimeter K, and in this form, L2 corresponds to the length J, L1 corresponds to the perimeter K, and the length J and the perimeter K have the relationship J>K, J=K, or J<K), and the measurement locations are virtual cross lines that intersect at right angles with the center of gravity O as the intersection point, and when the virtual cross lines are perpendicular to the sides of the rectangle, there are a total of nine measurement locations: one location at the center of gravity O, two locations on the virtual cross lines that are 0.25L1 vertically from the center of gravity O, two locations that are 0.25L2 horizontally from the center of gravity O, two locations that are 0.45L1 vertically from the center of gravity O, and two locations that are 0.45L2 horizontally from the center of gravity O.
(Condition 3)
Sputtering in-plane direction: The sputtering target is a disk-shaped target with a center O and a radius r, and the measurement locations are nine locations in total, on virtual cross lines that intersect at right angles with the center O as the intersection point, including one location at the center O, four locations at a distance of 0.45r from the center O, and four locations at a distance of 0.9r from the center O.
Target thickness direction: A cross section passing through one of the imaginary cross lines is formed, and the cross section is a rectangle with a length of t (i.e., the thickness of the target is t) and a width of 2r. The measurement points are the center X on a vertical transverse line passing through the center O, three points in total (referred to as points a, X, and b) that are 0.45t above and below the center X, two points on the cross section that are 0.9r away from point a towards the left and right sides, two points in total that are 0.9r away from point X towards the left and right sides, and two points in total that are 0.9r away from point b towards the left and right sides, for a total of nine measurement points.
(Condition 4)
Sputtering in-plane direction: The sputtering target is a rectangle with a vertical length of L1 and a horizontal length of L2 (however, this includes a square where L1 and L2 are equal. Alternatively, the rectangle includes a rectangle formed by unfolding the side of a cylinder with length J and perimeter K, and in this form, L2 corresponds to the length J, L1 corresponds to the perimeter K, and the length J and the perimeter K have the relationship J>K, J=K, or J<K), and the measurement locations are virtual cross lines that intersect at right angles with the center of gravity O as the intersection point, and when the virtual cross lines are perpendicular to the sides of the rectangle, there are a total of nine measurement locations: one location at the center of gravity O, two locations on the virtual cross lines that are 0.25L1 vertically from the center of gravity O, two locations that are 0.25L2 horizontally from the center of gravity O, two locations that are 0.45L1 vertically from the center of gravity O, and two locations that are 0.45L2 horizontally from the center of gravity O.
Target thickness direction: A cross section is formed that passes through a line parallel to either the vertical side L1 or the horizontal side L2 of the imaginary cross line, and when one side is horizontal L2, the cross section is a rectangle with a vertical length of t (i.e., the thickness of the target is t) and a horizontal length of L2, and the measurement points are the center X on a vertical transverse line that passes through the center of gravity O, three points in total (referred to as point a, point X, and point b) that are 0.45t above and below the center X, two points on the cross section that are 0.45L2 away from point a towards the left and right sides, two points in total that are 0.45L2 away from point X towards the left and right sides, and two points in total that are 0.45L2 away from point b towards the left and right sides, for a total of nine measurement points. The sputtering target according to claim 3, characterized in that, under (Condition 1) or (Condition 2), there are 40% or more locations where the relative integrated intensity of the second peak in the in-plane direction of the sputtering target by X-ray diffraction is 60% or more of the relative integrated intensity of the first peak. A sputtering target of an alloy comprising ruthenium as a first element and any one selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element,
the sputtering target has dispersed particles containing an intermetallic compound phase consisting of two elements, the first element and the second element,
The dispersed particles have a maximum major axis of 500 μm or less,
In (Condition 1) or (Condition 2), there is at least one location where the relative integrated intensity of the second peak in the in-plane direction of the sputtering target by X-ray diffraction is 60% or more of the relative integrated intensity of the first peak,
In (Condition 1) or (Condition 2), there are 40% or more portions where the relative integrated intensity of the second peak by X-ray diffraction in the sputtering in-plane direction of the sputtering target is 60% or more of the relative integrated intensity of the first peak,
A sputtering target characterized in that the crystallite size of the first peak is 400 Å or less . 6. The sputtering target according to claim 1 , wherein the content of the second element is 3 to 70 atomic %. 7. The sputtering target according to claim 1, wherein the oxygen content is 500 ppm or less. 8. The sputtering target according to claim 1, wherein the carbon content is 200 ppm or less. A method for producing a sputtering target of an alloy comprising ruthenium as a first element and any one element selected from boron, aluminum, titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, and tungsten as a second element, comprising:
a preparation step of preparing a raw material in which the first element and the second element have a predetermined element ratio;
an atomization step of obtaining alloy powder by atomization using the raw materials in a vacuum atmosphere of 1×10 ⁻² Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol % of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol % of hydrogen gas;
a sintering step of sintering the alloy powder by hot pressing, spark plasma sintering (SPS), or hot isostatic pressing (HIP) in a vacuum atmosphere of 50 Pa or less, a nitrogen gas atmosphere containing 0 to 4 vol% of hydrogen gas, or an inert gas atmosphere containing 0 to 4 vol% of hydrogen gas to obtain a sintered body,
The method for producing a sputtering target, wherein the alloy powder obtained by the atomization method has a maximum major axis of 500 μm or less. Between the atomizing step and the sintering step,
The method for producing a sputtering target according to claim 9 , further comprising a classification step of removing particles having a maximum major axis exceeding 500 μm from the alloy powder obtained by the atomization method.