Cr-Si-C sintered body

Abstract

The purpose of the present invention is to provide a high density Cr-Si-C-based sintered body containing chromium (Cr), silicon (Si), and carbon (C), and to provide at least one of a further high density Cr-Si-C-based sintered body, a sputtering target containing same, and a method for manufacturing a film using said sputtering target. With the present invention, it is possible to provide a Cr-Si-C-based sintered body that contains chromium (Cr), silicon (Si), and carbon (C), and that is characterized by having a relative density of 90% or more and a pore percentage of 13% or less.

Description

Technical Field

[0001] The present invention relates to a Cr—Si—C sintered body for film formation.

Background Art

[0002] In recent years, silicides such as chromium silicide like CrSi2 have been used as films (thin films) in many applications such as semiconductors and solar cells due to their characteristics. Industrially, the sputtering method is often adopted as a method for producing films, mainly thin films. However, since a composition (for example, a sintered body) containing a silicide such as CrSi2 generally has low strength, phenomena such as cracking occur during processing into a sputtering target and during film formation discharge. Therefore, it is known that it is difficult to use a composition containing a silicide as a sputtering target. Therefore, in Patent Document 1, a sputtering target of a crystal phase of Cr and Si (an alloy target mainly composed of a Cr phase and a Si phase) is produced by a spraying method. However, the sputtering target produced by the spraying method does not have sufficient strength in a composition region where the proportion of Cr is small. Similarly, a sputtering target produced by a spraying method using a powder of a silicide phase does not have sufficient strength.

[0003] In addition, in Patent Document 2, a composition having a fine eutectic structure is produced by a melting method. However, the composition obtained by the melting method does not have sufficient strength in a composition region where the proportion of the eutectic structure is small and the proportion of the primary crystal (that is, the crystal phase having the highest proportion in the composition) is large. Further, when such a composition is enlarged, due to the difference in the cooling rate between the phases, it is difficult to control the crystal structure, and the unevenness of the strength of the entire composition becomes large. Furthermore, since the silicide phase is brittle, Patent Documents 3 and 4 do not mention systems containing a large amount of silicide.

[0004] In recent years, as a sputtering target of a Cr—Si system with improved temperature change characteristics of the resistivity of a film (i.e., reduction of the temperature dependence of the resistivity), a sputtering target using a sintered body in which a third element such as carbon or boron is added to a Cr—Si system sintered body has been studied. However, it is difficult to increase the density of such a sintered body. Therefore, when a sintered body to which a third element is added is used as a sputtering target, a large amount of particles are generated, and the yield of the obtained film product, that is, the productivity, is low.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] An object of the present invention is to provide a high-density Cr—Si—C system sintered body containing chromium (Cr), silicon (Si), and carbon (C), and further to provide at least one of a high-density Cr—Si—C system sintered body, a sputtering target containing the same, and a method for manufacturing a film using the sputtering target. In particular, the present invention aims to provide at least one of a Cr—Si—C system sintered body in which particle generation is suppressed as compared with a conventional Cr—Si system sintered body, a method for manufacturing the same, a sputtering target containing the same, and a method for manufacturing a film using the sputtering target.

Means for Solving the Problems

[0007] The inventors of the present invention have intensively studied Cr-Si-C sintered compacts and their manufacturing processes. As a result, it has been found that by using rapidly solidified alloy powders (molten metal powders) such as gas atomized powders, high-density Cr-Si-C sintered compacts can be obtained, and that when a Cr-Si-C sintered compact having a specific structure is used as a sputtering target, the generation of particles is suppressed, leading to the completion of the present invention.

[0008] That is, the present invention is as described in the claims, and the gist and aspects of the present invention are as follows. (1) A Cr-Si-C sintered compact containing chromium (Cr), silicon (Si), and carbon (C), characterized in that the relative density of the sintered compact is 90% or more and the porosity is 13% or less. (2) The Cr-Si-C sintered compact according to (1), wherein the composition range is 1 to 20 wt% carbon, 20 to 70 wt% silicon, and the balance is chromium. (3) The Cr-Si-C sintered compact according to (1) or (2), containing chromium silicide and one or more selected from the group consisting of chromium carbide, silicon carbide, and carbon. (4) The Cr-Si-C sintered compact according to any one of (1) to (3), having one or more selected from the group consisting of CrSi, CrSi2, and Cr3Si as the main phase. (5) The Cr-Si-C sintered compact according to any one of (1) to (4), having an oxygen content of 1 wt% or less.

[0009] (6) The Cr-Si-C sintered compact according to any one of (1) to (5), having a flexural strength of 100 MPa or more. (7) A method for manufacturing a Cr-Si-C sintered compact according to any one of (1) to (6), comprising a step of mixing gas atomized powders of chromium and silicon and a carbon source containing at least one of chromium and silicon and carbon to obtain an alloy raw material powder, and a firing step of hot pressing the alloy raw material powder in a vacuum atmosphere at a pressure of 50 MPa or less and a firing temperature of 1350°C or more and 1800°C or less. (8) The production method according to (7), wherein the carbon source is a carbide containing at least one of chromium and silicon. (9) A sputtering target made of a Cr—Si—C sintered body according to any one of (1) to (6). (10) A method for producing a film by sputtering using the sputtering target according to (9). [Advantages of the Invention]

[0010] According to the present invention, there is provided a high-density Cr—Si—C sintered body containing chromium, silicon, and carbon. Further, there is provided at least one of a high-density Cr—Si—C sintered body, a sputtering target containing the same, and a method for producing a film using the sputtering target. Preferably, the Cr—Si—C sintered body of the present invention has a relative density of 90% or more. When used as a sputtering target, there are few particles when used as a sputtering target, and higher productivity can be obtained. In particular, the present invention provides at least one of a Cr—Si—C sintered body in which particle generation is suppressed as compared with a conventional Cr—Si sintered body, a production method thereof, a sputtering target containing the same, and a method for producing a film using the sputtering target. [Brief Description of the Drawings]

[0011]

Figure 1

[0012] Hereinafter, an example of an embodiment of the present invention will be shown and described in detail. The present invention is a Cr—Si—C sintered body containing chromium (Cr), silicon (Si), and carbon (C), and is characterized in that the relative density of the sintered body is 90% or more and the pore rate is 13% or less. The Cr-Si-C sintered body of the present invention (hereinafter, also referred to as "the sintered body of the present invention") is a sintered body mainly composed of chromium, silicon, and carbon, preferably a sintered body composed of chromium, silicon, and carbon. The sintered body of the present invention preferably contains chromium silicide and at least one selected from the group consisting of chromium carbide, silicon carbide, and carbon.

[0013] Examples of the chromium silicide contained in the sintered body of the present invention include one or more selected from the group consisting of chromium monosilicide, disilicide, and trisilicide, further one or more selected from the group consisting of CrSi, CrSi2, Cr3Si, and Cr5Si3, and still further one or more selected from the group consisting of CrSi, Cr3Si, and Cr5Si3. The sintered body of the present invention may contain two or more chromium silicides, preferably contains two or more selected from the group consisting of CrSi, CrSi2, Cr3Si, and Cr5Si3, more preferably contains two or more selected from the group consisting of CrSi, Cr3Si, and Cr5Si3, and still more preferably contains CrSi or Cr3Si and Cr5Si3.

[0014] The sintered body of the present invention preferably contains at least one of chromium carbide (Cr3C2), silicon carbide (SiC), and carbon (C), further at least one of silicon carbide and carbon, and still further silicon carbide. The sintered body of the present invention may be a sintered body composed of chromium silicide and at least one selected from the group consisting of chromium carbide, silicon carbide, and carbon, but in addition to these, it may contain at least one of silicon (Si) and chromium (Cr), and further may contain silicon.

[0015] The sintered body of the present invention preferably has a main phase of chromsilicide, more preferably has one or more selected from the group of CrSi, CrSi2 and Cr3Si as the main phase, and still more preferably has CrSi as the main phase. The main phase in the present invention refers to the crystal phase with the highest proportion in the crystal phase of the sintered body. For example, the mass ratio of the crystal phase of the main phase to the mass of the sintered body is more than 50 wt%, 60 wt% or more, or 70 wt% or more. Further, the mass ratio (wt%) of chromsilicide in the sintered body of the present invention can be exemplified as 70 wt% or more or 75 wt% or more, and 80 wt% or less or 95 wt% or less.

[0016] In the present invention, the crystal phase contained in the sintered body such as chromsilicide can be identified from its powder X-ray diffraction (hereinafter also referred to as "XRD") pattern. The XRD pattern can be measured by a general XRD apparatus (for example, RINT Ultima III, manufactured by Rigaku Corporation). The following conditions can be mentioned as the XRD measurement conditions in the present invention.

[0017] Accelerating current and voltage: 40 mA·40 kV X-ray source: CuKα ray (λ = 1.5405 Å) Measurement mode: continuous scan Scan condition: 2° / min Measurement range: 2θ = 20° to 80° Divergence vertical limiting slit: 10 mm Divergence / incidence slit: 1 / 2° Receiving slit: 0.3 mm The crystal phase of the sintered body may be identified by comparing the obtained XRD pattern with the database of ICDD.

[0018] The relative density of the sintered body of the present invention is characterized by being 90% or more, preferably 92% or more, more preferably 94% or more, and particularly preferably 96% or more. Further, the relative density may be 100% or less or 99% or less. In a sintered body having a relative density lower than 90%, when forming a film (i.e., when forming a film using the sintered body), a part of the sintered body detaches as coarse particles (i.e., particles are generated). As a result, coarse pores (for example, pores having a maximum length of 50 μm or more; hereinafter, also referred to as "coarse pores") are generated in the sintered body. At the same time, a film is formed while particles adhere as a film (i.e., a film incorporating particles is formed). Since the film incorporating particles has non-uniform physical properties and characteristics, it cannot be used. Thus, a sintered body having a relative density lower than 90% reduces the productivity of the film.

[0019] The "relative density" (%) in the present invention is the ratio of the measured density to the true density, and is a value obtained from (measured density [g / cm 3 / true density [g / cm 3 )×100. The measured density is the bulk density obtained from the dry mass with respect to the volume measured by the Archimedes method in accordance with JIS R 1634. Prior to the Archimedes method, the pretreatment is preferably the boiling method, and the sintered body may be boiled in water.

[0020] The true density is the density obtained from the following formula. d = 1 / {(R1 / M1)+(R2 / M2)+(R3 / M3)+(R4 / M4)+(R5 / M5)+(R6 / M6)+(R7 / M7)+(R8 / M8)+(R9 / M9)} In the above formula, d is the true density of the sintered body [g / cm 3 , and M1 to M8 and R1 to R8 are the true densities [g / cm 3 of the respective crystal phases of Si, C, Cr, SiC, CrSi, CrSi2, Cr3Si, Cr3C2, and Cr5Si3 contained in the sintered body, and the mass ratios [wt%] of the respective crystal phases in the sintered body.

[0021] For the true density of each crystal phase, the values described in the ICDD (Version 2.1502) of each crystal phase may be used. The following values can be exemplified as the true density. Si: 2.33 g / cm 3 (=M1) C: 2.28 g / cm 3 (=M2) Cr: 7.20 g / cm 3 (=M3) SiC: 3.12 g / cm 3 (=M4) CrSi: 5.36 g / cm 3 (=M5) CrSi2: 4.98 g / cm 3 (=M6) Cr3C2: 6.66 g / cm 3 (=M7) Cr5Si3: 5.87 g / cm 3 (=M8) Cr3Si: 6.46 g / cm 3 (=M9)

[0022] It should be noted that the ICDD numbers of each crystal phase are as follows: Si is 00-026-1481, C is 00-026-1080, Cr is 01-077-759, SiC is 00-002-105, CrSi is 03-065-3298, CrSi2 is 01-072-6184, Cr3C2 is 01-071-2287, Cr5Si3 is 01-072-0347, and Cr3Si is 01-070-301.

[0023] The mass ratio of each crystal phase is the mass ratio [wt%] of each crystal phase obtained by multiplying the molar ratio [mol%] obtained from the following formula by the true density of each crystal phase, where the crystal phases contained in the XRD pattern of the sintered body measured under the above conditions are identified, and the composition of the sintered body obtained from the composition analysis is Cr at X mol%, Si at Y mol%, and C at Z mol%. For example, when the crystal phases contained in the XRD pattern of the sintered body are CrSi, Cr5Si3, and SiC, and the composition of the sintered body obtained from the composition analysis is Cr at X mol%, Si at Y mol%, and C at Z mol%.

[0024] X = 1×M CrSi + 5×M Cr5Si3 Y = 1×M CrSi + 3×M Cr5Si3 + 1×M SiC Z = 1×M SiC In the above formula, M CrSi is the molar ratio [mol%] of CrSi, M Cr5Si3 is the molar ratio [mol%] of Cr5Si3, and M SiC is the molar ratio [mol%] of SiC.

[0025] In addition, the true density of the sintered body of the present invention containing three crystal phases (crystal phases A to C) can be obtained from the following formula.

[0026] d = (a + b + c) / ((a / Ma) + (b / Mb) + (c / Mc)) Or, d = 1 / ((Ra / Ma) + (Rb / Mb) + (Rc / Mc))

[0027] In the above formula, d is the true density of the sintered body [g / cm 3 , a, b, and c are the masses [g] of crystal phases A, B, and C contained in the sintered body, respectively. Also, Ma, Mb, and Mc are the true densities of crystal phases A, B, and C contained in the sintered body [g / cm 3 , respectively. Also, Ra, Rb, and Rc are the mass ratios [wt%] of crystal phases A, B, and C contained in the sintered body, respectively. Crystal phases A, B, and C are three selected from the group consisting of Si, C, Cr, SiC, CrSi, CrSi2, Cr3C2, and Cr5Si3, preferably (1) CrSi, Cr5Si3, and SiC, (2) Cr3Si, Cr5Si3, and SiC, or (3) CrSi2, Si, and C, more preferably CrSi, Cr5Si3, and SiC.

[0028] The sintered body of the present invention is characterized in that the pore ratio is 13% or less. When the pore ratio exceeds 13%, the productivity of the film decreases sharply when a film is formed (i.e., when a film is produced using the sintered body). In order to stably obtain high productivity, the pore ratio is preferably 8% or less, more preferably 6% or less, and particularly preferably 4% or less. The sintered body of the present invention may contain pores, but preferably does not contain pores (i.e., the pore ratio is 0%). Examples of the pore ratio of the sintered body of the present invention include 0% or more, more than 0%, 0.5% or more, or 1% or more.

[0029] In the present invention, the "pore ratio" is the ratio of pores determined from an observation view of the surface of the sintered body, and is the ratio of pores measured by image analysis of an observation view of the surface of a sintered body with a surface roughness Ra ≦ 0.02 μm. The pore ratio can be determined from an observation view of the surface of the sintered body in any state value before and after sputtering, but it is preferably determined from an observation view of the surface of the sintered body in any state value before and after sputtering. In the observation view, the shape of the pores is arbitrary, and examples thereof include substantially spherical, substantially polyhedral, or irregular shapes. The observation view may be an observation view obtained by laser microscope observation using a general laser microscope (for example, VX-250, manufactured by Keyence Corporation). Examples of the observation conditions for laser microscope observation are as follows.

[0030] Observation magnification: 200 times Observation field of view: 5 fields of view or more, preferably 5 to 8 fields of view, More preferably 5 fields of view

[0031] Figure 1 shows one field of view of the observation image obtained by laser microscope observation. As shown in Figure 1, in the observation image (100), the pores are confirmed as black regions (10), and the sintered body is confirmed as a white region (11). The pore ratio (%) of each field of view may be obtained by calculating the ratio (%) of the black region to the total area of the black and white regions in each observation image. The average value of the pore ratios of the observed fields of view may be taken as the pore ratio of the present invention. Image analysis may be performed by analyzing the obtained observation image using general-purpose image analysis software (for example, Image-Pro, manufactured by Media Cybernetics). The following conditions are listed as image analysis conditions. Note that the contrast ratio takes a value between 0 and 100.

[0032] Measurement field of view: 5 fields of view or more, preferably 5 - 8 fields of view, more preferably 5 fields of view Contrast ratio: 100

[0033] In the sintered body of the present invention, the silicon (Si) content is preferably in the range of 20 - 70 wt%, more preferably 25 - 65 wt%, more preferably 30 - 60 wt%, and even more preferably 35 - 55 wt%. When the silicon content is lower than 20 wt%, the amount of the semiconductor phase (i.e., SiC phase and Si phase) in the entire sintered body tends to be small, and the temperature change of the resistivity tends to be large. Also, when the silicon content is higher than 70 wt%, or further higher than 50 wt%, the amount of the semiconductor phase increases, and the temperature change of the resistivity of the obtained film tends to be large. Preferred silicon contents of the sintered body of the present invention include 20 wt% or more, 25 wt% or more, or 30 wt% or more, and also 70 wt% or less, 65 wt% or less, 50 wt% or less, 45 wt% or less, or 40 wt% or less.

[0034] The silicon content in the sintered body of the present invention is the mass ratio (wt%) of silicon to the mass of the sintered body of the present invention obtained by mass measurement. The silicon contained in the sintered body of the present invention can be measured by general methods used in this technical field, for example, by ICP analysis.

[0035] The sintered body of the present invention preferably has a carbon (C) content in the range of 1 to 20 wt%, more preferably 1 to 15 wt%, still more preferably 1 to 10 wt%, and even more preferably 5 to 10 wt%. When the carbon content is lower than 1 wt%, the temperature change characteristics of the resistivity of the film are not improved (that is, it is difficult to reduce the temperature dependence). On the other hand, when the carbon content is more than 20 wt%, a large amount of SiC phase showing a high resistivity close to insulation is likely to be formed in the sintered body, and when the SiC phase undergoes DC discharge, it is likely to cause the generation of particles. Preferred carbon contents of the sintered body of the present invention include 1 wt% or more, 3 wt% or more, or 4 wt% or more, and also 20 wt% or less, 15 wt% or less, 10 wt% or less, or 9 wt% or less.

[0036] The carbon content in the sintered body of the present invention is the mass ratio (wt%) of carbon to the mass of the sintered body. Carbon can be measured by a general method used in the art. For example, it can be exemplified that carbon is measured by a combustion-infrared absorption method using a general carbon-sulfur analyzer (for example, LECO-CS844 carbon-sulfur analyzer).

[0037] The sintered body of the present invention only needs the balance of silicon and carbon to be chromium. Examples of the chromium content of the sintered body of the present invention include more than 10 wt% and less than 79 wt%, further 15 to 75 wt%, and still further 35 to 70 wt%. Also, a preferred composition range of the sintered body of the present invention includes carbon of 1 to 20 wt%, silicon of 20 to 70 wt%, and the balance being chromium.

[0038] The metal elements (including semi-metal elements; the same applies hereinafter in this specification) contained in the sintered body of the present invention are preferably chromium and silicon. However, the sintered body of the present invention may contain metal impurities such as iron (Fe) and aluminum (Al) in addition to chromium (Cr), silicon (Si), and carbon (C). Metal elements such as iron and aluminum are contained as inevitable impurities. That is, the sintered body of the present invention may contain inevitable impurities, and may contain metal impurities (metal elements other than chromium and silicon) as inevitable impurities, and further may contain iron and aluminum as inevitable impurities. These metal impurities (metal elements other than chromium and silicon) may be contained in a total amount of 1 wt% or less, preferably 0.5 wt% or less, and more preferably 0.3 wt% or less. It is preferable that the sintered body of the present invention does not contain metal impurities, and examples thereof include a total amount of metal elements other than chromium and silicon of 0 wt% or more, more than 0 wt%, or 0.1 wt% or more.

[0039] Furthermore, the sintered body of the present invention may contain oxygen as long as it does not deteriorate the characteristics when used as a sputtering target. The amount of oxygen (O) in the sintered body of the present invention is preferably small, for example, preferably 1 wt% or less. When the amount of oxygen exceeds 1 wt%, many insulating oxide-derived particles are likely to be generated during film formation. More preferably, the amount of oxygen in the sintered body of the present invention is 0.5 wt% or less, and particularly preferably 0.1 wt% or less. Although it is preferable that the sintered body of the present invention does not contain oxygen (that is, the amount of oxygen is 0 wt%), examples thereof include more than 0 wt% or 0.01 wt% or more.

[0040] The amount of oxygen in the sintered body of the present invention is the mass ratio (wt%) of oxygen to the mass of the sintered body. The oxygen contained in the sintered body of the present invention can be measured by a general method used in this technical field. For example, the oxygen content can be measured by analysis using the inert gas fusion-infrared absorption method. For the inert gas fusion-infrared absorption method, a general oxygen-nitrogen analyzer (for example, LECO-ON736 oxygen-nitrogen analyzer) may be used.

[0041] The sintered body of the present invention may have any shape according to the purpose, and examples thereof include one or more selected from the group consisting of a disc shape, a columnar shape, a plate shape, a rectangular parallelepiped shape, a cubic shape, a polyhedral shape, and a substantially polyhedral shape.

[0042] The sintered body of the present invention preferably has a flexural strength of 100 MPa or more, particularly preferably 150 MPa or more. When the sintered body of the present invention is produced as a large-sized sintered body with a size exceeding 300 mm, the risk of cracking during processing, such as the occurrence of defects during processing, can be reduced by the flexural strength being within this range. Further, the occurrence of defects such as cracking when used as a sputtering target is also easily suppressed. The flexural strength of the sintered body of the present invention can be exemplified as being 300 MPa or less, 250 MPa, or 200 MPa or less. The flexural strength in the present invention may be measured by a method conforming to JIS R 1601.

[0043] As a preferred embodiment of the sintered body of the present invention, there is provided a sintered body characterized by having a porosity of 13% or less and containing one or more selected from the group consisting of chromsilicide and one or more selected from the group consisting of chromium carbide, silicon carbide, and carbon. The porosity is preferably 11% or less, 10% or less, or 6% or less, and preferably 0% or more, more than 0%, or 0.3% or more. Further, the chromsilicide preferably contains two or more selected from the group consisting of CrSi, CrSi2, Cr3Si, and Cr5Si3, more preferably contains one or more selected from the group consisting of CrSi, CrSi2, and Cr3Si, and more preferably is CrSi and Cr3Si and Cr5Si3. The sintered body more preferably contains CrSi and Cr3Si and silicon carbide. Furthermore, the sintered body preferably has a relative density of 90% or more, more preferably 93% or more and 100% or less. Furthermore, the sintered body preferably has a flexural strength of 150 MPa or more and 250 MPa or less, and more preferably 180 MPa or more and 220 MPa or less.

[0044] The manufacturing method of the sintered body of the present invention can be manufactured by a process including: (1) an alloy raw material powder preparation step of mixing powders using chromium, silicon, and carbon; and (2) a firing step of firing the obtained alloy raw material powder using a pressure sintering furnace such as a hot press furnace at a pressure of 50 MPa or less and a firing temperature of 1200°C to 1800°C.

[0045] Hereinafter, the manufacturing method of the sintered body of the present invention will be described for each step.

[0046] (1) Alloy raw material preparation step The raw materials used in the alloy raw material preparation step (hereinafter, also referred to as "starting materials") are chromium, silicon, and carbon. Chromium is preferably high-purity chromium, for example, 3N (purity 99.9% or more), and more preferably 4N (purity 99.99% or more) chromium. Silicon is preferably high-purity silicon, for example, 3N (purity 99.9% or more), more preferably 4N (purity 99.99% or more), and even more preferably 5N (purity 99.999% or more) silicon. Carbon (carbon source) may be carbon (C) and its compounds, and is preferably at least one carbide of chromium and silicon, and examples include one or more selected from the group consisting of chromium carbide (Cr3C2), silicon carbide (SiC), and carbon (C), and more preferably at least one of chromium carbide and silicon carbide. Chromium carbide and silicon carbide can also be regarded as starting materials for chromium and silicon, respectively.

[0047] For example, chromium (Cr), silicon (Si), chromium carbide (Cr3C2), silicon carbide (SiC), and carbon (C) can be used as the starting materials. Furthermore, in addition to chromium and silicon, or instead of chromium and silicon, the starting materials may include an alloy of chromium and silicon, and preferably include molten metal powders of chromium and silicon.

[0048] In the present invention, the "molten metal powder" refers to a powder in a state where the molten metal has cooled, and further to a powder in a state where the molten metal has been rapidly cooled, and is a powder having a fine structure. As the molten metal powder, for example, a powder obtained by one or more selected from the group consisting of rapidly quenched ribbons, arc melting, gas atomization, water atomization, centrifugal atomization, and vacuum atomization, further a powder obtained by one or more selected from the group consisting of rapidly quenched ribbons, arc melting, and gas atomization, and still further a powder obtained by gas atomization can be mentioned. Since the molten metal powder is a powder obtained without necessarily going through a pulverization process, and further a powder obtained without going through a pulverization process, the amount of impurities is more likely to be less than that of a powder obtained through a pulverization process.

[0049] The starting material preferably includes a powder obtained by gas atomization (hereinafter also referred to as "gas atomized powder"), and particularly preferably includes gas atomized powders of chromium and silicon. The particles produced by the gas atomization method become spherical with a diameter of about several tens of μm and have a fine crystal phase inside the sphere. Since the gas atomized powder is a powder having a small surface area and consisting of fine particles, it can be used to make the sintered body after firing have low oxygen and high strength, that is, to have a small amount of oxygen, and to be used as an alloy raw material powder from which a sintered body with high strength can be obtained.

[0050] As the gas atomized powder, for example, a powder having an average particle diameter of 5 μm or more and 100 μm or less, and also a powder having at least one of spherical and substantially spherical shapes, and further a powder composed of polycrystalline particles of chromide silicide, and still further a powder composed of particles containing polycrystals of chromide silicide having different crystal phases from each other can be exemplified.

[0051] The gas atomized powder preferably contains at least CrSi2 in the crystal phase, more preferably contains one or more selected from the group consisting of Si, Cr, CrSi, Cr3C2, and Cr5Si3 and CrSi2 in the crystal phase, and still more preferably contains at least one of Si and CrSi and CrSi2 in the crystal phase.

[0052] The conditions of the gas atomization method are arbitrary. For example, the treatment temperature for melting chromium and silicon is preferably the melting temperature + 50 to 300°C, and more preferably the melting temperature + 100 to 250°C. Thereby, a molten metal, that is, a metal in a liquid state, is obtained.

[0053] Here, the "melting temperature" is the temperature at which precursors such as raw material powders and flakes of chromium and silicon melt, and is a value specific to the substance. As the melting temperature, 1300°C to 1500°C can be exemplified. Therefore, the treatment temperature can be exemplified as 1350°C or higher and 1800°C or lower, and can be 1350°C or higher, 1370°C or higher, or 1390°C or higher, and can also be 1800°C or lower, 1700°C or lower, 1550°C or lower, or 1470°C or lower. When the difference between the melting temperature and the treatment temperature is small (for example, when the difference is less than 50°C), it is difficult to refine the alloy particles constituting the obtained powder, such as the melting point of the two-phase crystal phase with the higher melting point precipitating first. On the other hand, when the difference between the melting temperature and the treatment temperature is large, the particles sinter together after atomization, and the particles adhere to the wall surface of the gas atomization device, resulting in a poor powder recovery rate (poor yield).

[0054] For the gas atomization method, it is only necessary to supply a precursor from which gas atomized powders of chromium and silicon to be used as starting materials can be obtained. The precursor may be at least any one of chromium, silicon, and their compounds, and may be a powder, flake, or bulk of chromium and silicon, and is preferably a flake of chromium and silicon.

[0055] The precursor of chromium is preferably a frame of high-purity chromium, for example, flakes of chromium of 3N (purity 99.9% or more), and further 4N (purity 99.99% or more). The precursor of silicon is preferably a flake of high-purity silicon. For example, flakes of silicon of 3N (purity 99.9% or more), further 4N (purity 99.99% or more), and still further 5N (purity 99.999% or more) can be exemplified.

[0056] In the gas atomization method, gas atomized powder is obtained by dropping the obtained molten metal into a gas stream so as to pass through the gas stream. The gas stream may be an inert gas, and examples thereof include one or more selected from the group consisting of argon (Ar), nitrogen (N2), and helium (He), and further preferably argon. The pressure of the gas stream (hereinafter, also referred to as "gas pressure") may be 1 MPa or more, 4 MPa or more, or 6 MPa or more, and may be 10 MPa or less, and further preferably 9 MPa or less.

[0057] The gas atomization method may be at least one of a crucible type and an electrode type, and preferably the crucible type. The crucible used in the gas atomization method by the crucible type is, for example, a crucible made of one or more selected from the group consisting of carbon, alumina, magnesia, silicon nitride, zirconia, and boron nitride, or a crucible in which at least one of boron nitride and silicon carbide is coated on a main body made of one or more selected from the group consisting of carbon, alumina, magnesia, and zirconia.

[0058] The powder after gas atomization (gas atomized powder) is preferably managed (stored) in a vacuum atmosphere or an inert atmosphere such as nitrogen or argon, and is preferably not exposed to an oxidizing atmosphere before being subjected to the subsequent firing process. If the powder is exposed to an oxidizing atmosphere, such as by placing the powder in the air, oxidation occurs from the surface of the atomized powder, and the oxygen content of the powder increases.

[0059] It has been conventionally known to use, instead of molten metal powder, a mixed powder obtained by mixing chromium and silicon by a powder mixing method as a starting material for a sintered body. For example, even in fine powder mixing (physical mixing of fine powders), a high-strength sintered body can be produced. However, the sintered body obtained by firing the powder obtained by this method has a large amount of oxygen. On the contrary, by coarse grain mixing (physical mixing of powders containing coarse grains), low oxygenation of the obtained sintered body is possible, but its strength is low. Examples of production methods of other raw materials (molten metal powder) include rapid cooling methods such as rapid solidification strip and arc melting.

[0060] The oxygen content of the starting material is preferably low. If the oxygen content in the starting material is high, the oxygen content in the sputtering target using the sintered body of the present invention will increase. Such a large amount of oxygen is likely to cause the generation of particles. Each of the starting materials preferably has an oxygen content of 0.5 wt% or less, more preferably 0.1 wt% or less, and can be exemplified as 0 wt% or more, more than 0 wt% or 0.01 wt% or more.

[0061] Particularly preferred starting materials to be subjected to the alloy raw material preparation process include gas atomized powders of chromium and silicon, carbides of chromium and silicon, and further gas atomized powders of chromium and silicon, and chromium carbide.

[0062] The shape of the starting material is arbitrary, but it may be a powder. As a method for mixing the powder (starting material), any method may be used as long as the starting materials are uniformly mixed, and any mixer such as a V-type mixer or a mixer can be used. The mixing method may be at least either dry mixing or wet mixing, preferably dry mixing, and more preferably dry mixing using a V-type mixer. Thereby, an alloy raw material powder is obtained.

[0063] The mixing atmosphere is preferably an atmosphere in which the starting materials are less likely to be oxidized, and examples include at least one of a vacuum atmosphere and an inert atmosphere, further including at least one of a nitrogen atmosphere and an argon atmosphere, and further preferably an argon atmosphere.

[0064] Examples of the mixing speed, such as the rotation speed and stirring speed of the mixer, are 10 rpm or more and 200 rpm or less, and further preferably 50 rpm or more and 100 rpm or less. Also, the mixing time is 30 minutes or more and 5 hours or less, and further preferably 45 minutes or more and 3 hours or less.

[0065] The purity of the raw material (alloy raw material powder) obtained by the alloy raw material preparation process is preferably 99% or more, and more preferably 99.9% or more. If the raw material alloy powder contains a large amount of impurities (i.e., the purity is low), these impurities are likely to cause abnormal grain growth in the firing process. Also, these abnormally grown grains are likely to be the source of particles during film formation.

[0066] A preferred alloy raw material preparation process includes a step of mixing a molten metal powder of chromium and silicon (molten alloy powder of chromium and silicon) and a starting material containing a carbon source in at least one of a vacuum atmosphere and an inert atmosphere to obtain an alloy raw material powder. The molten metal powder is preferably a gas atomized powder of chromium and silicon. The carbon source preferably contains a carbide containing at least one of chromium and silicon, more preferably at least one of chromium carbide (Cr3C2) and silicon carbide (SiC), and even more preferably chromium carbide.

[0067] (2) Firing process In the firing process, the obtained alloy raw material powder is fired at a pressure of 50 MPa or less and a firing temperature of 1200°C to 1800°C using a pressure firing furnace such as a hot press furnace. It is preferable to use a pressure firing furnace such as a hot press furnace for firing. Since the diffusion coefficient of silicon is low, it is difficult to densify the obtained sintered body in a non-pressure furnace. In the firing process, the alloy raw material powder is fired by pressure sintering. As the pressure sintering in this process, at least one of hot pressing and hot isostatic pressing, preferably hot pressing, can be mentioned.

[0068] The hot pressing pressure during firing (hereinafter simply referred to as "pressure") is preferably 50 MPa or less. When it exceeds 50 MPa, it is difficult to prepare a hot pressing mold (press die) that can be pressurized (it is difficult to use a general-purpose mold). As a general-purpose mold, a carbon mold can be exemplified. When producing a large sintered body, the hot pressing pressure is preferably 5 to 45 MPa, more preferably 10 to 40 MPa, and particularly preferably 15 to 40 MPa. In this process, the preferable hot pressing pressure is 5 MPa or more, 10 MPa or more, or 15 MPa or more, and 50 MPa or less, 45 MPa or less, or 40 MPa or less.

[0069] The firing temperature is set to 1350°C to 1800°C. If it is less than 1350°C, the density of the obtained sintered body will not increase sufficiently. On the other hand, if the firing temperature exceeds 1800°C, there is a possibility that the material (sintered body) will dissolve during firing. Particularly preferable firing temperatures include 1300°C or higher, 1325°C or higher, or 1350°C or higher, and 1800°C or lower, 1600°C or lower, or 1400°C or lower.

[0070] The heating rate and the cooling rate are not particularly limited and can be appropriately determined in consideration of the volume of the firing furnace, the size and shape of the sintered body, and the ease of cracking. As the heating rate, for example, it can be 100°C / hour or higher or 150°C / hour or higher, and 300°C / hour or lower or 250°C / hour or lower.

[0071] The holding time during firing can be 1 to 5 hours, and more preferably 1.5 hours or more and 3.5 hours or less. By setting it to 1 hour or more, the temperature unevenness in the firing furnace and in the hot pressing mold (press die) is suppressed, and it becomes easier to obtain a sintered body having a uniform structure. By setting the holding time to 5 hours or less, sintering with industrial productivity becomes possible. The firing atmosphere is preferably a vacuum atmosphere, a vacuum reduced pressure atmosphere, or an inert atmosphere such as argon, more preferably an argon atmosphere or a vacuum atmosphere, and even more preferably a vacuum atmosphere. By firing in a vacuum atmosphere, it becomes easier to obtain a sintered body having a composition equivalent to that of the raw material alloy powder. In the present invention, the vacuum atmosphere and the vacuum reduced pressure atmosphere are used interchangeably.

[0072] Particularly preferred firing steps include a step of hot-pressing the alloy raw material powder in a vacuum atmosphere at a pressure of 50 MPa or less and a firing temperature of 1350°C or higher and 1800°C or lower. The hot pressing is preferably a hot press treatment, and the alloy raw material powder preferably contains molten metal powders of chromium and silicon, and more preferably is a powder composition containing molten metal powders of chromium and silicon and carbides of at least one of chromium and silicon.

[0073] A particularly preferred manufacturing method of the sintered body of the present invention includes a step of mixing gas atomized powders of chromium and silicon and a carbon source containing at least one of chromium and silicon and carbon to obtain an alloy raw material powder, and a firing step of hot pressing the alloy raw material powder in a vacuum atmosphere at a pressure of 50 MPa or less and a firing temperature of 1350°C or higher and 1800°C or lower. The carbon source is preferably a carbide containing at least one of chromium and silicon, and more preferably chromium carbide.

[0074] The sintered body of the present invention can be ground into a plate shape using a machining machine such as a surface grinding machine, a cylindrical grinding machine, a lathe, a cutting machine, or a machining center. Thereby, any shape according to the purpose may be adopted.

[0075] The sintered body of the present invention can be used for known silicide applications such as structural materials, electrode materials, and semiconductor materials, and is particularly preferably used as a sputtering target (hereinafter, also simply referred to as "target"). It can be used as a sputtering target made of the sintered body of the present invention.

[0076] The method for manufacturing the sputtering target is arbitrary. The sintered body of the present invention may be directly used as the sputtering target. Alternatively, if necessary, a backing plate made of oxygen-free copper, titanium, or the like, and indium solder or the like may be used for the backing tube to bond (bond) the sintered body of the present invention and the backing plate, thereby making the sintered body of the present invention into a sputtering target.

[0077] Also, a film (thin film) can be manufactured by sputtering using the obtained sputtering target. That is, the sintered body of the present invention can be made into a sputtering target including the sintered body of the present invention, a backing plate, and a backing tube, and can be used in a method for manufacturing a film by sputtering using the sputtering target.

[0078] The sputtering conditions are arbitrary, and for example, the following conditions can be mentioned.

[0079] Film formation power: 100 W or more and 800 W or less, Preferably 150 W or more and 300 W or less Gas pressure: 0.2 Pa or more and 1.0 Pa or less, Preferably 0.3 Pa or more and 0.7 Pa or less Gas atmosphere: Inert atmosphere, preferably argon atmosphere Film formation time: 0.5 hours or more and 3 hours or less, Preferably 0.5 hours or more and 1.5 hours or less

[0080] In order to reduce the temperature dependence of the resistivity, it is preferable to perform heat treatment (annealing treatment) on the film after sputtering. The following conditions can be mentioned as the annealing treatment conditions.

[0081] Annealing atmosphere: Vacuum atmosphere Annealing time: 1 hour Annealing temperature: Any temperature from 200°C to 600°C

[0082] The film obtained by using the sintered body of the present invention (hereinafter, also referred to as "the film of the present invention") may have any thickness. For example, the film thickness is 5 nm or more or 10 nm or more, and may be 1 μm or less or 500 nm or less.

[0083] The film of the present invention is a Si-Cr-C-based film, and is an amorphous film of chromium silicide and one or more selected from the group consisting of chromium carbide, silicon carbide, and carbon. Preferably, it is an amorphous film of chromium silicide and silicon carbide or carbon.

[0084] The film of the present invention is a film present on a substrate, that is, a film in a state formed on the substrate, and is particularly a sputtered film. Therefore, unlike a self-standing film, the film of the present invention can also be regarded as a laminate in which the film of the present invention and the substrate are laminated. The substrate may be a substrate made of any material according to the purpose, and examples include a substrate made of one or more selected from the group consisting of metals, semimetals, ceramics, glass, and polymers, further a substrate made of one or more selected from the group consisting of metals, semimetals, and glass, and still further a substrate made of glass.

[0085] The film of the present invention preferably has a small change rate of resistivity when the temperature of the film changes by 1°C, that is, a so-called temperature coefficient of resistance (hereinafter, also referred to as "TCR"). The maximum value of TCR (hereinafter, also referred to as "maximum TCR") at a measurement temperature of 40°C to 150°C is preferably 100 ppm / °C or less or 98 ppm / °C or less.

[0086] In addition, the minimum value of TCR (hereinafter, also referred to as "minimum TCR") at a measurement temperature of 40°C to 150°C may be -25 ppm / °C or more or 0 ppm / °C or more.

[0087] In the present invention, the TCR can be obtained from the following formula using the value of the resistivity of the film measured with a general resistivity measuring device (for example, the 8403 type AC / DC Hall measurement system, manufactured by Toyo Technica Co., Ltd.).

[0088] TCR = (R - R 30 ) / {R 30 × (T - 30)} × 10 6 In the above formula, TCR is the temperature coefficient of resistance [ppm / °C], R is the resistivity [Ω·cm] at the measurement temperature, R 30 is the resistivity [Ω·cm] at 30°C, and T is the measurement temperature [°C]. The film of the present invention preferably has an average value of TCR (hereinafter, also referred to as "average TCR") of 100 ppm / °C or less, 50 ppm / °C or less, or 15 ppm / °C or less at a measurement temperature of 40°C to 150°C. The average TCR can be 0 ppm / °C or more, 1 ppm / °C or more, or 10 ppm / °C or more.

[0089] The average TCR is the average of the absolute values of TCR measured at 10°C intervals at a measurement temperature of 40°C to 150°C, and can be obtained from the following formula. Average TCR = (TCR 40 + TCR 50 + … + TCR 150 ) / 12

[0090] In the above formula, TCR 40 is the absolute value of TCR [ppm / °C] at a measurement temperature of 40°C, TCR 50 is the absolute value of TCR [ppm / °C] at a measurement temperature of 50°C, etc., and is the absolute value of TCR [ppm / °C] at each measurement temperature measured at 10°C intervals.

[0091] The film of the present invention preferably has a slope of the straight line (hereinafter, also referred to as "TCR slope") of the linear approximation formula (linear approximation) obtained from 13 points of the plot of TCR measured at 10°C intervals in the temperature range of 30°C to 150°C of ±0.7 ppm / °C 2 and preferably ±0.5 ppm / °C 2 , ±0.3 ppm / °C2 , ±0.2 ppm / °C 2 , ±0.1 ppm / °C 2 or 0 (zero) ppm / °C 2 is preferable. When the TCR slope is within this range, the detection sensitivity in sensor applications used in environments with large temperature changes such as in-vehicle sensors is stabilized.

Example

[0092] Hereinafter, the present invention will be described more specifically by way of examples, but the present invention is not limited thereto. Each measurement in this example was performed as follows.

[0093] (1) Crystal phase of the sintered body The crystal phase of the sintered body was measured and identified by an XRD pattern under the above-described conditions.

[0094] (2) Relative density of the sintered body The relative density of the sintered body was determined as the ratio (%) of the measured density to the true density. First, in accordance with JIS R 1634, the bulk density obtained from the dry mass with respect to the volume measured by the Archimedes method was measured, and this was taken as the measured density.

[0095] The true density was determined from the following formula. d = 1 / {(R1 / M1)+(R2 / M2)+(R3 / M3)+(R4 / M4)+(R5 / M5)+(R6 / M6)+(R7 / M7)+(R8 / M8)+(R9 / M9)}

[0096] In the above formula, d is the true density of the sintered body [g / cm 3 , and M1 to M9, and R1 to R9 are the true densities [g / cm 3 and mass ratios [wt%] of Si, C, Cr, SiC, CrSi, CrSi2, Cr3Si, Cr3C2, and Cr5Si3 contained in the sintered body, respectively.

[0097] The crystal phases contained in the sintered body were identified from the XRD patterns measured under the above conditions, and the composition of the sintered body was determined by ICP analysis. From the measured elements and the obtained crystal phases, the mass ratio of each crystal phase was determined.

[0098] Also, for a sintered body composed of three phases, the true density of the sintered body was calculated from the following formula using the mass a [g] of crystal phase A, the mass b [g] of crystal phase B, the mass c [g] of crystal phase C, and their respective true densities Ma [g / cm 3 , Mb [g / cm 3 , Mc [g / cm 3 . d = (a + b + c) / ((a / Ma) + (b / Mb) + (c / Mc))

[0099] (3) Porosity of the sintered body The sintered body was mirror-polished, observed with a laser microscope, and measured by image analysis from the obtained sintered body microstructure image. The mirror polishing was performed using DP-suspension 1 μm (manufactured by Marumoto Striar Co., Ltd.) so that the surface roughness Ra ≤ 2 μm. At least five arbitrary fields of view were observed, the area of pores was calculated by image analysis, the porosity was measured five times (i.e., once for each field of view), and the average value of the measurement results of the porosity of each field of view was taken as the porosity.

[0100] Measurement field of view (observation magnification): 200 times Porosity of each field of view (%) = (Area of pores calculated by image analysis / Measured area) × 100

[0101] (4) Number of large pores A sintered body with a diameter of 10.16 cm was cut out from an arbitrary location of the sintered body, In bonding was performed, and it was used as a sputtering target. Under the following conditions, a sputtering test was conducted, and the number of holes with a maximum length of 50 μm or more in the target after sputtering was counted with a laser microscope and regarded as large pores.

[0102] (5) Oxygen content After grinding the surface of the sintered body by 1 mm or more, the oxygen content in a sample cut out from an arbitrary part of the sintered body (a rectangular shape with a length of 3 mm, a width of 20 mm, and a thickness of 4 mm) was measured by the fusion-infrared absorption method.

[0103] Measurement method: Impulse furnace melting-infrared absorption method Apparatus: LECO ON736 oxygen and nitrogen analyzer

[0104] (6) Flexural strength The flexural strength of the sintered body was measured by a method conforming to JIS R 1601. Test method: Three-point bending test Span: 30 mm Specimen size: 3×4×40 mm Crosshead speed: 0.5 mm / min.

[0105] (Example 1) As the precursor, Cr flakes (4N): 33 wt% and Si flakes (5N): 67 wt% were used. Cr flakes and Si flakes were melted in a carbon crucible at a treatment temperature of 1650 °C to obtain a molten metal of chromium and silicon. Then, powder (gas atomized powder) was produced by the gas atomization method in which the molten metal was dropped so as to pass an argon gas stream with a gas pressure of 7 MPa, and this was used as the starting material for chromium and silicon. The gas atomized powder had a crystal phase composed of CrSi2 and Si. Then, the gas atomized powder and Cr3C2 powder (product name: Chromium Carbide, manufactured by PPM) were dry-mixed at 60 rpm for 1 hour using a V-type mixer in an argon atmosphere so that the gas atomized powder was 62 wt% and the Cr3C2 powder was 38 wt%, and an alloy raw material powder with Cr being 55 wt%, Si being 39 wt%, and C being 6 wt% was obtained.

[0106] Next, this alloy raw material powder was put into a carbon mold (press die: diameter 15.2 cm) and fired by the hot pressing method to obtain the sintered body of this example. The firing conditions are shown below.

[0107] Firing furnace: Hot press furnace Heating rate: 200 °C / hour Heating atmosphere: Vacuum reduced pressure atmosphere (vacuum atmosphere) Firing atmosphere: Vacuum reduced pressure atmosphere (vacuum atmosphere) Firing temperature: 1350 °C Pressure: 40 MPa Firing time: 3 hours

[0108] As a result, a disk-shaped sintered body with a sintered body size of diameter 15.2 cm × thickness 7 mm and no microcracks was obtained.

[0109] From the results of XRD measurement, it was confirmed that the sintered body of this example is a Cr-Si-C system sintered body composed of CrSi, Cr5Si3 and SiC. From the measurement results of the XRD, the relative density of the sintered body of this example is that the crystal phase A: CrSi (true density 5.36 [g / cm 3 ) is 52 wt%, the crystal phase B: Cr5Si3 (true density 5.87 / cm 3 ) is 27 wt%, and the crystal phase C: SiC (true density 3.21 / cm 3 ) is 21 wt%, calculated using the true density calculated as such.

[0110] (Examples 2 to 7) A sintered body (Cr-Si-C system sintered body) was produced in the same manner as in Example 1 except that the firing conditions were changed to the conditions shown in Table 1. All of the obtained sintered bodies were Cr-Si-C system sintered bodies composed of CrSi, Cr5Si3 and SiC.

[0111] (Example 8) As precursors, Cr flakes (4N): 59 wt% and Si flakes (5N): 41 wt% were used. These were melted in a carbon crucible at a processing temperature of 1650 °C to obtain a molten metal. Gas atomized powder was produced by the gas atomization method by dropping the molten metal so as to pass an argon gas stream with a gas pressure of 7 MPa. The gas atomized powder had a crystal phase composed of CrSi2 and CrSi. Thereafter, the alloy raw material powder of this example with Cr being 69 wt%, Si being 26 wt%, and C being 5 wt% was obtained by mixing in the same manner as in Example 1 except that the Cr3C2 powder and the gas atomized powder were mixed so that the gas atomized powder was 62 wt% and the Cr3C2 powder was 36 wt%.

[0112] The alloy raw material powder was fired in the same manner as in Example 1 except that the alloy raw material powder was used, and a Cr-Si-C sintered body was obtained, which was used as the sintered body of this example. From the results of XRD measurement, the relative density of the sintered body was calculated using the true density calculated with crystal phase A: Cr5Si3 (true density 5.87 [g / cm 3 ) being 23 wt%, crystal phase B: Cr3Si (true density 6.46 / cm 3 ) being 61 wt%, and crystal phase C: SiC (true density 3.21 / cm 3 ) being 16 wt%.

[0113] (Example 9) As precursors, Cr flakes (4N): 42 wt% and Si flakes (5N): 58 wt% were used. These were melted in a carbon crucible at a processing temperature of 1650 °C to obtain a molten metal. Gas atomized powder was produced by the gas atomization method by dropping the molten metal so as to pass an argon gas stream with a gas pressure of 7 MPa. The gas atomized powder had a crystal phase composed of CrSi2 and Si. Thereafter, the alloy raw material powder of this example with Cr being 40 wt%, Si being 55 wt%, and C being 5 wt% was obtained by mixing in the same manner as in Example 1 except that the C powder and the gas atomized powder were mixed so that the gas atomized powder was 95 wt% and the C powder was 5 wt%.

[0114] The sintered body was fired in the same manner as in Example 1 except that the alloy raw material powder was used, and a disk-shaped sintered body with a size of 15.2 cm in diameter and 7 mm in thickness and no microcracks was obtained, which was used as the sintered body of this example.

[0115] From the results of XRD measurement, it was confirmed that the sintered body of this example was a Cr-Si-C-based sintered body composed of CrSi2, Si, and C. From the results of the XRD measurement, the relative density of the sintered body of this example was calculated using the true density calculated with CrSi2 being 83 wt%, Si being 12 wt%, and C being 5 wt%.

[0116] (Example 10) An alloy raw material powder of this example with Cr being 36 wt%, Si being 49 wt%, and C being 15 wt% was obtained in the same manner as in Example 9 except that C powder and gas atomized powder were mixed so that the C powder was 15 wt%.

[0117] The sintered body was fired in the same manner as in Example 1 except that the alloy raw material powder was used, and a disk-shaped sintered body with a size of 15.2 cm in diameter and 7 mm in thickness and no microcracks was obtained. From the results of XRD measurement, it was confirmed that the sintered body of this example was a Cr-Si-C-based sintered body composed of CrSi2, Si, and C. From the results of the XRD measurement, the relative density of the sintered body of this example was calculated using the true density calculated with CrSi2 being 74 wt%, Si being 11 wt%, and C being 15 wt%.

[0118] (Comparative Example 1) A sintered body composed of crystal phases of CrSi, Cr5Si3, and SiC was obtained in the same manner as in Example 1 except that powder mixing was performed with a V-type mixer to obtain an alloy raw material powder with Cr powder: 31 wt%, CrSi2 powder: 48 wt%, and SiC powder: 21 wt%.

[0119] (Comparative Example 2) In the same manner as in Example 9, a gas atomized powder with Cr being 42 wt% and Si being 58 wt% and having a crystal phase composed of CrSi2 and Si was obtained. A sintered body was produced in the same manner as in Comparative Example 1, except that the gas atomized powder was used, the firing temperature was 1250 °C, and the pressure was 15 MPa.

[0120] From the results of XRD measurement, it was identified that the sintered body of this example was a Cr-Si based sintered body (sintered body of chromium silicide) composed of CrSi2 and Si. From the results of the XRD measurement and the composition analysis by ICP, the relative density of the sintered body of this comparative example was calculated using the true density calculated with CrSi2 being 87 wt% and Si being 13 wt%.

[0121] The production conditions of Examples 1 to 10 and Comparative Examples 1 and 2 are shown in Table 1, and the evaluation results of the obtained sintered bodies are shown in Table 2.

[0122]

Table 1

[0123]

Table 2

[0124] <Confirmation of large pores> The sintered bodies of Example 1 and 8 and Comparative Example 1 were each lathe processed, and a disk-shaped sintered body with a diameter of 10.16 mm and a thickness of 5 mm was cut out from the sintered body. By bonding the obtained sintered body to a backing plate, a sputtering target was formed, and film formation (sputtering) was performed on a glass substrate (product name: non-alkali glass C, manufactured by Mitsuru Kogaku Kenkyusho) under the following conditions. Film formation power: 800 W Gas pressure: 0.5 Pa Gas atmosphere: Ar only (argon atmosphere) Film formation time: 1 hour

[0125] The surface of the target after film formation was observed with a laser microscope. As a result, it was confirmed that no holes (large pores) with a pore diameter of 50 μm or more were generated in the target of the example.

[0126]

Table 3

[0127] <Film formation> Sputtering was performed and film formation was carried out in the same manner as <Confirmation of large pores>, except that the sintered bodies of Example 7, 9 and 10, and Comparative Example 2 were used, and the following conditions were applied. Film formation power: 200 W Gas pressure: 0.5 Pa Gas atmosphere: Argon atmosphere Film formation time: 1 hour

[0128] Film formation was performed multiple times to obtain a plurality of films (sputtering films). The obtained films (sputtering films) were each annealed in a vacuum atmosphere for 1 hour at any temperature in the range of 200 °C to 600 °C in 10 °C increments. As a result, a plurality of sputtering films with a film thickness of 100 nm were obtained for each example. The films after annealing were evaluated under the following conditions.

[0129] (Resistivity) The resistivity of the film was measured at 30 °C using an 8403 type AC / DC Hall measurement system (manufactured by Toyo Technica). The measurement was performed on a glass substrate with a sputtering film cut out in a 1 cm square.

[0130] (TCR) The resistivity of the film was measured at intervals of 10 °C from 30 °C to 150 °C, and the TCR at each temperature was obtained from the following formula. TCR (ppm / °C) = (R - R 30 ) / (R 30 × (T - 30)) × 10 6

[0131] The maximum value in the TCR measured at 40 °C to 150 °C was defined as the maximum TCR, the minimum value as the minimum TCR, and the average of the absolute values of the TCR as the average TCR.

[0132] (TCR slope) The TCR values from 40 °C to 150 °C obtained by the measurement of TCR were plotted with temperature - TCR, and a linear approximation formula obtained from the plot was determined. The value of the slope of the linear approximation formula was defined as the TCR slope.

[0133] The annealing temperature at which the average TCR value was the smallest and the evaluation results of the film after annealing treatment at the annealing temperature are shown in the following table.

[0134]

Table 4

[0135] From the above table, it can be seen that compared with the examples, Comparative Example 2 has a higher relative density and a lower porosity rate, yet the obtained film has a large TCR slope and a large change in resistivity with temperature change.

[0136] The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2020 - 129947 filed on July 31, 2020, and Japanese Patent Application No. 2021 - 63955 filed on April 5, 2021 are hereby incorporated by reference as the disclosure of the specification of the present disclosure.

Explanation of reference signs

[0137] 100 Observation diagram 10 Black region (pores) 11 White region (sintered body)

Claims

1. A Cr—Si—C based sintered body containing chromium (Cr), silicon (Si), and carbon (C), wherein the relative density of the sintered body is 90% or more and the porosity is 13% or less, and containing chromium silicide and at least one selected from the group consisting of chromium carbide, silicon carbide, and carbon. The Cr—Si—C based sintered body is characterized by this.

2. The Cr—Si—C based sintered body according to Claim 1, wherein the composition range is 1 to 20 wt% of carbon, 20 to 70 wt% of silicon, and the balance is chromium.

3. The Cr—Si—C based sintered body according to Claim 1 or 2, wherein the chromium silicide is at least one selected from the group consisting of CrSi, CrSi₂, Cr₃Si, and Cr₅Si₃.

4. CrSi, CrSi ２ and Cr ３ The Cr—Si—C sintered compact according to any one of claims 1 to 3, comprising as a main phase one or more selected from the group consisting of Si and CrSi.

5. The Cr—Si—C based sintered body according to any one of Claims 1 to 4, wherein the oxygen content is 1 wt% or less.

6. The Cr—Si—C based sintered body according to any one of Claims 1 to 5, wherein the flexural strength is 100 MPa or more.

7. A step of obtaining alloy raw material powder by mixing gas atomized powder of chromium and silicon, and a carbon source containing at least one of chromium and silicon and carbon, and a firing step of hot pressing the alloy raw material powder in a vacuum atmosphere at a pressure of 50 MPa or less and a firing temperature of 1350°C or more and 1800°C or less. The manufacturing method of the Cr—Si—C based sintered body according to any one of Claims 1 to 6.

8. The manufacturing method according to Claim 7, wherein the carbon source is a carbide containing at least one of chromium and silicon.

9. A sputtering target made of the Cr—Si—C based sintered body according to any one of Claims 1 to 6.

10. A method for manufacturing a film by sputtering using the sputtering target according to Claim 9.

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