Heat dissipating material, heat dissipating component, and method for manufacturing heat dissipating material

Abstract

To provide a heat dissipation material for a heat dissipation component that is suitably used in a processing step in which large heat input is applied; a heat dissipation component; an electrostatic chuck comprising the heat dissipation component; and a method for producing the heat dissipation material.SOLUTION: In a heat dissipation material, a Mo phase 1 and a Ti phase 2 coexist. The heat dissipation material contains Ti in an amount of 3-50 atom% with a remainder being Mo. A method for producing a heat dissipation material comprises a mixing step for mixing powder containing Mo and powder containing Ti to obtain a mixture and a sintering step for sintering the mixture.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat dissipating material that can be suitably used in processing steps with particularly large heat input, a heat dissipating component including the heat dissipating material, an electrostatic chuck, and a method for producing the heat dissipating material. [Background technology]

[0002] Generally, during the manufacture of semiconductor devices, a thin film formation process and an etching process are repeatedly performed on a silicon wafer, resulting in the formation of fine wiring and semiconductor elements. An electrostatic chuck is used to secure the wafer during the etching process. Specifically, the wafer is placed on a ceramic layer made of ceramic (e.g., Al2O3, Y2O3, etc.) and is secured by electrostatic force. During the etching process, the wafer is heated by the influence of plasma, etc. For this reason, a base plate, which serves as a heat dissipation material, is bonded below the ceramic layer to cool the wafer during the etching process.

[0003] Patent Document 1 discloses an electrostatic chuck in which aluminum or an aluminum alloy is used as the material for the base plate. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-103389 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in recent years, the integration density of semiconductors has increased, and the heat input during etching has been increasing.

[0006] The present invention has been made in view of the above-described problems, and has an object to provide a heat dissipation material, a heat dissipation component, an electrostatic chuck including the heat dissipation component, and a method for manufacturing the heat dissipation material, which are suitable for use in processing steps in which a large heat input is applied. [Means for solving the problem]

[0007] The above object of the present invention is achieved by the following configuration [1] relating to a heat dissipation material.

[0008] [1] Mo and Ti phases coexist, Contains 3 atomic % or more and 50 atomic % or less of Ti, A heat dissipation material, the balance of which is Mo.

[0009] Furthermore, preferred embodiments of the present invention relating to the heat dissipation material relate to the following [2] and [3].

[0010] [2] The heat dissipating material according to [1], characterized in that, when the proportion of the Mo phase in the heat dissipating material measured by X-ray diffraction is [Mo phase] in atomic %, and the concentration of all the Mo contained in the heat dissipating material is [total Mo] in atomic %, the alloying ratio A represented by the following formula (1) is 15% or more and 80% or less. Formula (1): A = (1 - [Mo phase] / [total Mo]) × 100

[0011] [3] A heat dissipation material used in an electrostatic chuck having a base plate, a ceramic layer provided on the base plate, and an electrode that generates static electricity on the surface of the ceramic layer, characterized in that the heat dissipation material according to [1] or [2] is used as a material for the base plate.

[0012] The above object of the present invention is achieved by the following configuration [4] relating to a heat dissipation component.

[0013] [4] A heat dissipation component comprising the heat dissipation material according to [1] or [2].

[0014] The above object of the present invention is achieved by the following configuration [5] relating to an electrostatic chuck.

[0015] [5] An electrostatic chuck comprising: a base plate made of the heat dissipation component according to [4]; a ceramic layer provided on the base plate; and an electrode for generating static electricity on the surface of the ceramic layer.

[0016] The above object of the present invention is achieved by the following configuration [6] relating to a method for producing a heat dissipating material.

[0017] [6] A method for producing the heat dissipating material according to any one of [1] to [3], a mixing step of mixing a powder containing Mo and a powder containing Ti to obtain a mixture; a sintering step of sintering the mixture. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide a heat dissipation material, a heat dissipation component, an electrostatic chuck including the heat dissipation component, and a method for manufacturing the heat dissipation material that are suitable for use in a processing step in which a large heat input is applied. [Brief explanation of the drawings]

[0019] [Figure 1] FIG. 1 is a photograph, taken with a scanning electron microscope, of the structure of the heat dissipation material according to this embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing an example of an electrostatic chuck according to an embodiment of the present invention. [Figure 3] FIG. 3 is a graph showing the measurement results of the invention examples and comparative examples, with the vertical axis representing the thermal conductivity and the horizontal axis representing the linear expansion coefficient. [Figure 4] FIG. 4 is a graph showing the relationship between relative density and alloying ratio, with the vertical axis representing relative density and the horizontal axis representing alloying ratio. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present inventors have conducted extensive research into materials for heat dissipation components that can be used in processing steps with particularly large heat input.

[0021] As mentioned above, the recent trend toward higher integration of semiconductors has led to increased heat input during etching. However, aluminum alloys, which have traditionally been used as base plate materials, have poor heat resistance, and heat treatment (aging treatment) during the manufacturing stage of aluminum alloys is generally carried out at temperatures up to 200°C. Therefore, if the temperature of the base plate exceeds 200°C during the etching process, the material properties of the aluminum alloy cannot be maintained.

[0022] Furthermore, when heat dissipation components are used in processes with large heat inputs, the thermal expansion of the heat dissipation components can have a large effect, and the size change rates of the heat dissipation components and the surrounding materials can differ significantly. As a result, strain occurs between the heat dissipation components and the surrounding materials, which can cause peeling or cracking of the surrounding materials.

[0023] Furthermore, in order to apply heat dissipation components to processing steps with large heat input, they must exhibit high heat dissipation properties.

[0024] That is, in order to apply a heat dissipation component to a processing process with a large heat input, it is important that the heat dissipation component has high heat resistance, an appropriate thermal expansion coefficient, and a high thermal conductivity. The inventors have discovered that a heat dissipation component having desired properties can be obtained by using a material in which a Mo phase and a Ti phase coexist and the Ti content is appropriately controlled. Furthermore, the inventors have discovered that by controlling the alloying ratio of Mo and Ti within an appropriate range, a good relative density can be obtained and a highly reliable heat dissipation material can be manufactured. The present invention was made based on these findings.

[0025] Hereinafter, embodiments of the heat dissipation material for realizing high heat resistance, an appropriate coefficient of linear expansion, and high thermal conductivity will be described in detail.

[0026] [Heat dissipation material] Among aluminum alloys, the tensile strength of 2000 series aluminum alloys, which are said to have high heat resistance, drops to 200 MPa at a temperature of 200°C (Katsumi Koyama, "High-Strength, Heat-Resistant Aluminum Alloys," Furukawa-Sky Review, No. 6, 2010, p. 13, Figure 7). On the other hand, Mo is a high-melting-point metal with a melting point of 2623°C, and has extremely excellent heat resistance at temperatures of around 200°C. Specifically, the tensile strength of Mo is 550 MPa or more at 200°C (Takashi Murakami et al., "Molybdenum and Molybdenum Alloys," Journal of the Japan Welding Society, Vol. 57 (1988), No. 4, p. 293, Figure 2).

[0027] The heat dissipation material according to this embodiment contains Mo as its main component, which significantly improves its heat resistance. Mo is also one of the pure metals with high thermal conductivity, more than twice that of iron and more than eight times that of titanium. Therefore, by using Mo as its main component, the heat dissipation material can exhibit high heat dissipation properties.

[0028] Furthermore, the inventors have found that, in order to obtain a heat dissipation material with a desired linear expansion coefficient, it is effective to allow a Mo phase and a Ti phase to coexist rather than completely dissolving Ti in Mo. More specifically, Ti has a larger linear expansion coefficient than Mo, and the linear expansion coefficient of the resulting alloy can be made closer to that of the ceramic layer material. However, if the Ti phase is not dispersed, the effect of adding Ti is weakened, and the linear expansion coefficient of the heat dissipation material approaches that of Mo.

[0029] As will be described in detail later, the heat dissipation material according to this embodiment is a sintered body obtained by mixing and sintering Mo powder and Ti powder, and more specifically, it is a sintered composite having a structure in which a Mo phase (body-centered cubic structure) and a Ti phase (hexagonal close-packed structure or body-centered cubic structure) coexist. This sintered composite has characteristics such as the inclusion of pores, and therefore it can be confirmed that it is a sintered body by observing the structure.

[0030] FIG. 1 is a photograph, taken with a scanning electron microscope, of the structure of the heat dissipating material according to Example No. 3, described below. As shown in FIG. 1, the heat dissipating material according to this embodiment has a black Ti phase 2 dispersed in a Mo phase 1, which is the main component. This indicates that a metal / metal composite material is formed in this embodiment. Furthermore, since this Ti phase 2 has the effect of increasing the linear expansion coefficient, adjusting the Ti content can provide a heat dissipating material for heat dissipating components that is suitable for use in processes involving large heat inputs.

[0031] The contents of the components contained in the heat dissipation material of this embodiment will be described below.

[0032] (Ti: 3 atomic% or more and 50 atomic% or less) If the Ti content in the heat dissipation material is less than 3 atomic %, the effect of increasing the linear expansion coefficient of the heat dissipation material cannot be sufficiently obtained, and there is a risk that the ceramic layer (such as an Al2O3 layer or a YO3 layer) will peel off from the base plate or that the ceramic layer will crack. Therefore, the Ti content in the heat dissipation material should be 3 atomic % or more, preferably 4 atomic % or more, and more preferably 8 atomic % or more. On the other hand, if the Ti content in the heat dissipation material exceeds 50 atomic %, the thermal conductivity decreases and the required properties of the heat dissipation material cannot be obtained. Therefore, the Ti content in the heat dissipation material is set to 50 atomic % or less, preferably 45 atomic % or less, and more preferably 35 atomic % or less. In this way, by appropriately adjusting the Ti content in the heat dissipation material, it is possible to match the linear expansion coefficient to that of the ceramic layer (Al2O3 layer, Y2O3 layer, etc.), which makes it possible to prevent the ceramic layer (Al2O3 layer, Y2O3 layer, etc.) from peeling off from the base plate and also achieves excellent heat dissipation properties.

[0033] In this specification, when the proportions of Ti and Mo in the heat dissipation material are expressed in atomic %, the proportions of Ti atoms and Mo atoms are expressed in atomic % when the total of Ti atoms and Mo atoms in the heat dissipation material is 100 atomic %.

[0034] (Remainder: Mo) The thermally conductive material according to this embodiment contains Ti in the above range, with the remainder being Mo. Therefore, it is possible to obtain excellent heat resistance, as well as the properties of high thermal conductivity and an appropriate linear expansion coefficient.

[0035] The heat dissipation material according to this embodiment does not contain Cu. If Cu is present in the chamber during the etching process, the chamber may be contaminated with Cu, which may affect the wiring structure. Therefore, the heat dissipation material according to this embodiment, which does not contain Cu, is particularly suitable for use in the etching process.

[0036] The heat dissipation material according to this embodiment may contain various impurities to the extent that the effects of the present invention are not impaired. Possible impurities include, for example, oxygen, nitrogen, carbon, etc. derived from the powder raw materials. Other impurities may also be present, such as Fe, Si, Mn, Mg, Cl, Al, V, Mn, Ni, and Nb. Empirically, it is considered preferable to limit the amount of oxygen to 3% by mass or less and each of the other elements to 0.3% by mass or less. The content of the impurities is expressed in mass % when the total amount of Mo content and Ti content in the heat dissipation material according to this embodiment is taken as 100 mass %. Furthermore, as long as these elements are within the above-mentioned numerical ranges, the effects of this embodiment are not hindered even if they are contained as unavoidable impurities or even if they are intentionally added.

[0037] The inventors have found that by controlling the alloying ratio of Mo and Ti within an appropriate range, it is possible to obtain not only excellent thermal conductivity and linear expansion coefficient but also good relative density. The alloying ratio of Mo and Ti will be described in more detail below.

[0038] <Alloying rate A: 15% or more and 80% or less> In a mixed powder of pure Mo powder and pure Ti powder, atomic diffusion occurs during the sintering stage, forming an alloyed region between Mo and Ti. The inventors discovered that this alloyed region has lower hot deformation resistance than pure Mo alone, and that the sintering is promoted as the alloying ratio increases, improving the relative density. In other words, if a heat dissipation component containing a heat dissipation material with a low relative density is used as a base plate, there is a concern that the refrigerant used to cool the base plate may leak, or that cracks or fractures may be promoted due to thermal stress or mechanical stress associated with repeated use of the base plate. Therefore, obtaining a heat dissipation material with a good relative density leads to the production of a highly reliable base plate. In this specification, the alloying ratio is defined as the ratio of Mo consumed by alloying to the total Mo contained in the heat dissipation material.

[0039] The method for measuring the alloying ratio is explained below. First, the heat dissipation material after sintering is measured by X-ray diffraction (XRD). Next, the spectrum obtained by XRD is analyzed by whole powder pattern fitting (WPPF) to identify the Mo phase, Mo x Ti y The atomic fractions (atomic %) of the Al phase and the Ti phase are then determined. These values can then be used to calculate the alloying ratio according to equation (1) described below.

[0040] In this embodiment, a heat dissipation material with good relative density can be obtained by specifying the alloying ratio A represented by the following formula (1): In the following formula (1), [Mo phase] is the proportion of Mo phase in the heat dissipation material, as determined by X-ray diffraction, expressed in atomic %, and [Total Mo] is the concentration of all Mo contained in the heat dissipation material, expressed in atomic %.

[0041] The Mo concentration in the heat dissipating material is the proportion of Mo atoms in atomic percent when the total of Ti atoms and Mo atoms in the heat dissipating material is 100 atomic percent. The proportion of Mo phase in the heat dissipating material is the proportion of Mo phase, Mo x Ti y This is the ratio of Mo atoms constituting the Mo phase, expressed in atomic %, when all atoms constituting the Mo phase and the Ti phase are taken as 100 atomic %. More specifically, [Mo phase] is the Mo phase obtained by the above-mentioned full pattern fitting method, Mo x Ti y The alloying ratio A can be calculated from the mass fraction of the Mo phase in the mass fractions of the Mo phase and the Ti phase (total of 100 mass%) using the following formula (2): In the following formula (1), the alloying ratio A calculated using atomic % is the same as the alloying ratio calculated using mass % instead of atomic %.

[0042] As will be described in detail later, the thermally conductive material can be manufactured by mixing a powder containing Mo with a powder containing Ti to form a mixture, and then sintering this mixture. Therefore, the concentrations of Ti powder and Mo powder at the time of mixing generally become the Ti and Mo concentrations in the thermally conductive material after sintering. Therefore, if it is confirmed that there is only a margin of error between the concentrations at the time of mixing and the concentrations in the thermally conductive material after sintering, the Mo concentration at the time of powder mixing can be used as the Mo concentration ([total Mo]) in the thermally conductive material.

[0043] Formula (1): A = (1 - [Mo phase] / [total Mo]) × 100 Equation (2): [Mo phase] = ({Mo phase} / atomic weight of Mo) / ([Mo content] / atomic weight of Mo + [Ti content] / atomic weight of Ti) In the above formula (2), the [Mo phase] is the proportion of the Mo phase in the heat dissipating material, as determined by X-ray diffraction, expressed in atomic %. {Mo phase} is the mass fraction of the Mo phase obtained by XRD. x Ti yThis is a value expressed in mass % of the proportion of the Mo phase when the total of the Mo phase and the Ti phase is taken as 100 mass %. [Mo content] is the total content of Mo contained in the thermally conductive material expressed in mass %. [Ti content] is the total content of Ti contained in the thermal interface material expressed in mass %.

[0044] When the alloying ratio A calculated by the above formula (1) is 15% or more, a higher relative density can be obtained, and the occurrence of cracks, breakage, etc. due to the load of thermal stress or mechanical stress can be suppressed. Therefore, the alloying ratio A calculated by the above formula (1) is preferably 15% or more, more preferably 30% or more, and even more preferably 40% or more. Furthermore, when the alloying ratio A calculated by the above formula (1) is 80% or less, the sintering temperature and time can be prevented from becoming too high or too long, thereby suppressing wear on the sintering mold and maintaining good productivity. Therefore, the alloying ratio A calculated by the above formula (1) is preferably 80% or less, more preferably 70% or less, and even more preferably 60% or less. By controlling the alloying ratio to such a level, a heat dissipation material can be obtained that has good thermal conductivity and linear expansion coefficient, as well as high relative density. Furthermore, when a heat dissipation component containing such a heat dissipation material is used in a base plate, the performance and reliability of the base plate can be improved.

[0045] Here, we will explain example manufacturing conditions for a heat dissipation material having an alloying ratio within the above range. The alloying ratio is due to atomic diffusion between Mo and Ti, and can be controlled by changing the temperature and time required for post-processing that applies thermal load, such as the sintering process or bonding, which is performed as needed. For example, the thermal load for sintering and bonding is approximately 800°C to 1400°C, a holding time of 5 minutes to 16 hours, and a pressure of 2 MPa to 50 MPa, and can be performed under conditions suited to the equipment and powder characteristics.

[0046] Furthermore, the relative density will be explained below. In this embodiment, by controlling the alloying ratio A within an appropriate range, a good relative density can be obtained, and as a result, a highly reliable heat dissipation material can be obtained. The relative density D is calculated by multiplying the density d obtained by the water displacement method (Archimedes method) or the like. m The value of the theoretical density d t That is, the relative density D can be expressed by the following formula (3).

[0047] Equation (3): D=(d m / d t ) x 100

[0048] In addition, the theoretical density d t can be calculated by the following formula (4).

[0049] Formula (4):d t =100 / ([Ti content] / [Ti specific gravity]+[Mo content] / [Mo specific gravity]) In the above formula (4), the "Ti content" is the content of Ti contained in the thermally conductive material expressed in mass%, the "Ti specific gravity" is the specific gravity of pure Ti, the "Mo content" is the content of Mo contained in the thermally conductive material expressed in mass%, and the "Mo specific gravity" is the specific gravity of pure Mo.

[0050] The relative density D is preferably 98% or more, more preferably 98.5% or more, even more preferably 99% or more, and even more preferably 99.5% or more. Furthermore, the relative density D is preferably 100.0% or more, more preferably 100.5% or more, and even more preferably 101.0% or more.

[0051] [Heat dissipation parts] The heat dissipation component according to this embodiment is obtained by machining the heat dissipation material (sintered composite) according to this embodiment. It has excellent heat resistance, high thermal conductivity, and an appropriate linear expansion coefficient. Therefore, when this heat dissipation component is used, it can dissipate heat sufficiently in a processing process with a large heat input. Furthermore, because this heat dissipation component has an appropriate linear expansion coefficient, even when the effects of thermal expansion are significant in a process with a large heat input, the size change rate of the heat dissipation component is close to that of the surrounding material. Therefore, distortion between the heat dissipation component and the surrounding material can be suppressed, preventing peeling or cracking of the surrounding material.

[0052] [Electrostatic chuck] Fig. 2 is a schematic cross-sectional view showing an example of an electrostatic chuck according to an embodiment of the present invention. As shown in Fig. 2, an electrostatic chuck 10 includes a base plate 11 made of the heat dissipation component described above, a ceramic layer 12 provided on the base plate 11, and an electrode 14 that generates static electricity on a surface 12a of the ceramic layer 12. A coolant flow path 13 is provided inside the base plate 11. Note that an electrostatic chuck is a device that grips a member using electrostatic force, and can be applied to semiconductor manufacturing equipment, electrostatic robot hands, etc.

[0053] Various types of semiconductor manufacturing equipment are available, including polishing equipment, developing equipment, exposure equipment, and etching equipment. For example, an etching equipment includes the electrostatic chuck 10 according to the present embodiment and a plasma generation / processing chamber in which the electrostatic chuck 10 is disposed. When the electrostatic chuck 10 according to the present embodiment is used in an etching equipment, a silicon wafer (not shown) is placed on the electrostatic chuck 10 disposed in the plasma generation / processing chamber, and a voltage is applied to the electrode 14 to generate static electricity on the surface of the ceramic layer 12, thereby securing the silicon wafer. The wafer surface is then etched using plasma in a vacuum atmosphere within the plasma generation / processing chamber. Because plasma generates high temperatures, the temperature rises during etching. Therefore, the wafer is cooled by flowing a coolant through a coolant flow path 13 formed in the base plate 11.

[0054] As described above, the recent trend toward higher integration of semiconductors has resulted in increased heat input during etching, requiring base plates with high heat resistance. The heat dissipation material and heat dissipation member according to this embodiment are suitable for use in processes involving high heat input. That is, the electrostatic chuck according to this embodiment can effectively cool silicon wafers even during high-temperature etching processes that correspond to the miniaturization and high integration of semiconductor devices. Furthermore, because the heat dissipation component has an appropriate linear expansion coefficient, distortion between the ceramic layer and the base plate can be suppressed during the etching process, preventing peeling and cracking of the ceramic layer. Furthermore, because the heat dissipation component constituting the base plate does not contain Cu, contamination of the etching chamber can be prevented even when used in the etching process. Therefore, the electrostatic chuck according to this embodiment is particularly suitable for use in etching equipment.

[0055] [Method of manufacturing heat dissipation materials] The method for producing a heat dissipation material according to this embodiment is a method for producing the heat dissipation material, and includes a mixing step of mixing a powder containing Mo and a powder containing Ti to obtain a mixture, and a sintering step of sintering the mixture.

[0056] The sintering method in the sintering step is not particularly limited, and for example, spark plasma sintering (SPS), hot pressing, hot isostatic pressing (HIP), etc. can be used. In addition, the sintering conditions in the sintering step are also not particularly limited, and the sintering can be carried out under conditions according to the characteristics of the equipment and the characteristics of the powder, with the sintering temperature being approximately 800°C to 1600°C, the sintering holding time being 5 minutes to 3 hours, and the pressure being 10 MPa to 50 MPa as guidelines.

[0057] In this specification, the Mo-containing powder and Ti-containing powder used as the heat dissipation material include powders containing oxygen, nitrogen, carbon, etc. derived from the powder raw materials as impurities. For example, alloy powders may be used as the heat dissipation material as long as the effects of the present invention are not impaired.

[0058] Furthermore, by performing contour machining and groove machining on the material sintered by the SPS method or the hot pressing method, or on the material sintered by the HIP method and then forged, a heat dissipation component such as a base plate can be manufactured. Furthermore, by forming a ceramic layer on the upper surface of the obtained heat dissipation component by diffusion bonding and then performing finishing by cutting, an electrostatic chuck in which the base plate and the ceramic layer are bonded can be manufactured. In addition to the diffusion bonding, methods for bonding the base plate and ceramic include brazing, bonding with an adhesive, and fastening with screws.

[0059] The heat dissipation material, heat dissipation component, electrostatic chuck, and method for manufacturing a heat dissipation material according to the present invention are not limited to the above-described embodiments, and can be modified as desired within the scope of the present invention. In the above-described embodiment, the heat dissipation component is used as a base plate of an electrostatic chuck used during etching in a semiconductor manufacturing device, but the present invention is not limited to this, and the heat dissipation material and heat dissipation component of the present invention can be used as any heat dissipation material or heat dissipation component. Because the heat dissipation material of the present invention has the above-described characteristics, it is particularly suitable for use as a material for heat dissipation components used in processing steps that involve a large heat input. [Example]

[0060] The heat dissipating material according to the present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples, and modifications can be made within the scope of the present invention, and all such modifications are included within the technical scope of the present invention. Furthermore, the heat dissipating material and its manufacturing conditions described below are merely examples, and the present invention is not limited to the following examples.

[0061] [First Example] (Manufacturing of heat dissipating materials) First, Mo powder and Ti powder were mixed to obtain mixtures so as to form Mo-Ti sintered composites with various compositions. The resulting mixtures were then sintered by a powder sintering method using a hot press method or an SPS method to produce sintered bodies of Invention Examples No. 1 to No. 4. A sintered body was also produced by sintering only Mo powder, which was designated Comparative Example No. 1. Comparative Examples No. 2, No. 3, and No. 4 were made of known alumina (Al2O3), pure aluminum, and 2024-T6 alloy, a 2000-series aluminum alloy known as duralumin, respectively. Inventive Example No. 1, Inventive Example No. 2, and Comparative Example No. 1 were sintered by hot pressing, and Inventive Example No. 3 and Inventive Example No. 4 were sintered by SPS.

[0062] (Component analysis) The components of Invention Examples No. 1 to No. 4 were analyzed by inductively coupled plasma (ICP) optical emission spectroscopy. The analysis results of the components of the heat dissipation materials in the invention examples and the materials of the sintered bodies in the comparative examples are shown in Tables 1 and 2 below. Note that the compositions shown in Table 1 are expressed in atomic % as the proportions of Ti atoms and Mo atoms when the total of Ti atoms and Mo atoms is 100 atomic %.

[0063] (Measurement of thermal conductivity) The specific heat of the obtained sintered body at room temperature was measured by a differential scanning calorimetry (DSC) and the thermal diffusivity was measured by a flash method, and the thermal conductivity was calculated from these values.

[0064] (Measurement of linear expansion coefficient) The linear expansion coefficient of the obtained sintered body at 40° C. to 400° C. was measured by thermomechanical analysis (TMA method).

[0065] (Observation of material structure) The obtained sintered body was mirror-polished, and the material structure was observed by taking a backscattered electron image using a scanning electron microscope.

[0066] The measurement results of the thermal conductivity and linear expansion coefficient are shown in Tables 1 and 2 below. The thermal conductivity and linear expansion coefficient of Al2O3 of Comparative Example No. 2 can be found on the KYOCERA Japan website ("Alumina Al2O3", [searched December 13, 2022], Internet<URL;https: / / www.kyocera.co.jp / prdct / fc / material-property / material / alumina / index.html> ) were used to cite the values for the material code "AO476O." Furthermore, for the thermal conductivity and linear expansion coefficient of pure Al in Comparative Example No. 3, the values were used to cite the values listed in "Metal Data Book" (edited by the Japan Institute of Metals, Maruzen, 2004). Furthermore, for the thermal conductivity and linear expansion coefficient of Al alloy (2024-T6) in Comparative Example No. 4, the values were used to cite the values listed in "Aluminum Handbook," Japan Aluminum Association, 2007.

[0067] The thermal conductivity of pure Al shown in Table 2 below is measured at 200°C, and the linear expansion coefficient is measured at 20 to 400°C. The linear expansion coefficient of Al alloy shown in Table 2 below is measured at 20 to 300°C.

[0068] [Table 1]

[0069] [Table 2]

[0070] (Evaluation of Examples and Comparative Examples) Figure 3 is a graph showing the measurement results for the invention examples and comparative examples, with the vertical axis representing thermal conductivity and the horizontal axis representing linear expansion coefficient. The dotted line in the figure indicates the linear expansion coefficient of alumina. Figure 1 is a micrograph of the structure of invention example No. 3. Observation of the material structures of invention examples Nos. 1 to 4 confirmed the coexistence of Mo and Ti phases in all invention examples, as in the micrograph shown in Figure 1. Furthermore, as shown in Tables 1 and 2 above, the linear expansion coefficients of the sintered bodies of invention examples Nos. 1 to 4 were higher than those of comparative example No. 1, which does not contain Ti, and were closer to those of Al2O3, which is used as a material for electrostatic chucks. In particular, the linear expansion coefficients of the sintered bodies of invention examples Nos. 1 to 4 were significantly closer to those of alumina, comparative example No. 2, than those of the conventional materials of comparative examples Nos. 3 and 4. Furthermore, when the sintered bodies of invention examples Nos. 1 to 4 were compared, it was confirmed that the linear expansion coefficient increased with an increase in the Ti concentration in the sintered body, approaching the linear expansion coefficient of Al2O3.

[0071] The above results show that when heat dissipation components are manufactured using the sintered bodies of invention examples 1 to 4, the resulting heat dissipation components have excellent heat dissipation properties. Furthermore, because the linear expansion coefficient is close to that of the ceramic layer made of alumina bonded to the heat dissipation component, it is possible to prevent cracking or peeling of the ceramic layer. Furthermore, the sintered bodies of invention examples 1 to 4 are primarily composed of Mo and contain a predetermined amount of Ti, both of which are highly heat-resistant components, and therefore have high heat resistance. Furthermore, because the sintered bodies of invention examples 1 to 4 do not contain Cu, when heat dissipation components made of these sintered bodies are used in the etching process of semiconductor manufacturing equipment, contamination inside the chamber can be suppressed.

[0072] [Second Example] (Manufacturing of heat dissipating materials) Mo-Ti sintered compacts (heat dissipation materials) were produced by mixing pure Mo powder and pure Ti powder and sintering them using a powder process that involved hot pressing and SPS.

[0073] (Measurement of Ti powder concentration during mixing and Ti concentration in the heat dissipation material after sintering) Separately from the production of the heat dissipation material described above, Mo powder and Ti powder were mixed in various ratios, and the Ti powder concentration was calculated when the Mo powder and Ti powder were mixed. The mixed mixture was then sintered using a powder process that involved hot pressing and SPS to produce sintered test pieces. The Ti concentration of each test piece was then analyzed using inductively coupled plasma (ICP) atomic emission spectroscopy, and compared with the Ti powder concentration described above. The calculated concentration at the time of mixing and the analysis results of the Ti concentration after sintering are shown in Table 3 below.

[0074] [Table 3]

[0075] As shown in Table 3, when the analytical values of the Ti powder concentration when Mo powder and Ti powder were mixed and the Ti concentration in the sintered heat dissipation material were compared, only a slight difference was found, approximately within the margin of error. Therefore, in this example, the concentrations of Ti powder and Mo powder when mixed were considered to be the Ti and Mo concentrations in the sintered heat dissipation material.

[0076] (Calculation of relative density D and alloying ratio A) The relative density D and alloying ratio A of the obtained Mo—Ti sintered body (heat dissipation material) were calculated. The relative density D can be calculated by the following formula (3).

[0077] Equation (3): D=(d m / d t ) x 100 However, d m is the density of the sintered body measured by the underwater displacement method, and d t is the theoretical density d calculated by the following formula (4) t is.

[0078] Formula (4):d t =100 / ([Ti content] / [Ti specific gravity]+[Mo content] / [Mo specific gravity]) In the above formula (4), [Ti content] refers to the amount of Ti contained in the thermally conductive material, and here, the value used is the amount of Ti powder contained in the raw material powder expressed in mass%. [Ti specific gravity] refers to the specific gravity of pure Ti. [Mo content] refers to the amount of Mo contained in the thermally conductive material, and here, the value used is the amount of Mo powder contained in the raw material powder expressed in mass%. [Mo specific gravity] refers to the specific gravity of pure Mo. The specific gravity of pure Ti was set to 4.508, and the specific gravity of pure Mo was set to 10.222.

[0079] In addition, to calculate the alloying ratio A, the sintered body was measured by X-ray diffraction (XRD), and the spectrum with a 2θ angle of 20 to 140° was analyzed by the WPPF method to determine the Mo phase, Mo x Ti y The concentrations of the Ti and Ti phases were measured. The conditions of the program used for the analysis by the WPPF method and the measurement conditions by XRD are shown below.

[0080] Analysis conditions using the WPPF method Analysis program: JADE by Materials Data Inc. (MDI) PRO (version 8) Database: ICDD PDF-4+ XRD measurement conditions Micro X-ray diffraction equipment: Rigaku Corporation RINT-RAPIDII Collimator diameter: 300 μm ω angle: 20~25°(2° / sec) φ angle: rotation (1° / sec)

[0081] The alloying ratio A was calculated using the following formula (1) from the content of the Mo phase in the sintered body obtained by the above XRD analysis and the concentration of all Mo contained in the sintered body ([Total Mo] (atomic %)). In the following formulas (1) and (2), [Mo phase] is a value expressed in atomic % of the proportion of Mo atoms constituting the Mo phase in the sintered body as identified by X-ray diffraction, and [Total Mo] is a value expressed in atomic % of the concentration of all Mo contained in the sintered body. Furthermore, {Mo phase} is the mass fraction of the Mo phase obtained by XRD, and the total Mo content is expressed in atomic %. x Ti y The Mo content is the percentage of the Mo phase expressed in mass% when the total of the Mo phase and the Ti phase is taken as 100 mass%. The Mo content is the total Mo content contained in the sintered body expressed in mass%. The Ti content is the total Ti content contained in the sintered body expressed in mass%. As mentioned above, the concentration of Mo powder in the raw material powder can be used as the Mo concentration in the sintered body.

[0082] Formula (1): A = (1 - [Mo phase] / [total Mo]) × 100 Equation (2): [Mo phase] = ({Mo phase} / atomic weight of Mo) / ([Mo content] / atomic weight of Mo + [Ti content] / atomic weight of Ti)

[0083] (Measurement of thermal conductivity and linear expansion coefficient) The thermal conductivity and linear expansion coefficient were measured using the same method as in Example 1. The various measurement and calculation results for Examples 21 to 29 are shown in Table 4 below. In Table 4 below, Example 21 corresponds to Example 4 in Example 1 above, and Example 29 corresponds to Example 3 in Example 1 above.

[0084] [Table 4]

[0085] (Evaluation of invention examples) Figure 4 is a graph showing the relationship between relative density and alloying ratio, with the vertical axis representing relative density and the horizontal axis representing alloying ratio. As shown in Figure 4, as the alloying ratio increases, the relative density value also increases, approaching 100%. Furthermore, the inventive examples with alloying ratios of 15 to 80%, shown by the arrows in Figure 4, showed particularly good relative densities. Furthermore, when the alloying ratio was in the range of 30% or more, the relative density became even higher, and values approaching or exceeding 100% could be obtained.

[0086] As shown in the first and second examples, a heat dissipation material in which a Mo phase and a Ti phase coexist can be obtained by controlling the Ti content within a predetermined range and further controlling the alloying ratio within an appropriate range, thereby providing a sound heat dissipation material that not only has excellent thermal conductivity and linear expansion coefficient but also has a high relative density. Furthermore, a base plate using the heat dissipation material obtained in this way does not have to worry about refrigerant leakage, and can suppress the occurrence of cracks or fractures that occur when thermal or mechanical stress is applied, thereby extending the life of the base plate and improving its reliability. [Explanation of symbols]

[0087] 1 Mo phase 2 Ti phase 10 Electrostatic chuck 11 Base Plate 13 Refrigerant flow path 12 ceramic layers 14 electrodes

Claims

1. Mo phase and Ti phase coexist, Contains 3 atomic % or more and 50 atomic % or less of Ti, A heat dissipation material, the balance of which is Mo, for use as a heat dissipation component or a part thereof.

2. 2. The heat dissipation material according to claim 1, characterized in that, when the proportion of the Mo phase in the heat dissipation material measured by an X-ray diffraction method is defined as [Mo phase] in atomic %, and the concentration of all the Mo contained in the heat dissipation material is defined as [total Mo] in atomic %, an alloying ratio A represented by the following formula (1) is 15% or more and 80% or less: Formula (1): A = (1 - [Mo phase] / [total Mo]) × 100

3. A Mo phase and a Ti phase coexist, Contains 3 atomic % or more and 50 atomic % or less of Ti, A heat dissipation component comprising a heat dissipation material, the balance of which is Mo.

4. In the heat dissipation material, 4. The heat dissipation component according to claim 3, wherein the proportion of the Mo phase in the heat dissipation material measured by an X-ray diffraction method is defined as [Mo phase] in atomic %, and the concentration of all the Mo contained in the heat dissipation material is defined as [total Mo] in atomic %, the alloying ratio A represented by the following formula (1) is 15% or more and 80% or less: Formula (1): A = (1 - [Mo phase] / [total Mo]) × 100

5. A method for producing the thermal interface material according to claim 1 or 2, comprising: a mixing step of mixing a powder containing Mo and a powder containing Ti to obtain a mixture; a sintering step of sintering the mixture.

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