joint

Abstract

To provide a jointed structure of ceramic plates and MMC plates having high bonding strength. [Solution] This joint comprises a ceramic plate, an MMC plate provided opposite one side of the ceramic plate and composed of (i) Si, C and Ti, or (ii) Al, Si and C, and a bonding layer provided between the ceramic plate and the MMC plate, which bonds the ceramic plate and the MMC plate, and which mainly contains Al. The MMC plate is located at a predetermined depth D from the bonding interface between the bonding layer and the MMC plate. Al The MMC plate has an Al-enriched layer in which Al is distributed at a higher concentration than in other parts of the plate, and the depth of the Al-enriched layer D Al The size is 40 μm or larger.

Description

[Technical Field]

[0001] This disclosure relates to a joint. [Background technology]

[0002] Circuit formation in semiconductor device manufacturing is generally performed by plasma etching. Plasma etching is carried out by introducing an inert gas into a vacuum chamber within a plasma etching apparatus to create plasma. The plasma etching apparatus is equipped with an electrostatic chuck assembly that functions as a susceptor for which the wafer to be etched is placed. A typical electrostatic chuck assembly comprises an electrode-embedded ceramic plate that functions as an electrostatic chuck and a cooling plate that supports the bottom surface of the electrode-embedded ceramic plate. The wafer is electrostatically adsorbed onto the electrode-embedded ceramic plate and then plasma-etched while fixed to the electrostatic chuck assembly. The cooling plate, on the other hand, is provided on the bottom surface of the electrode-embedded ceramic plate and is configured to remove heat generated in the wafer by plasma etching. The electrode-embedded ceramic plate generally has a configuration in which internal electrodes such as electrostatic chuck (ESC) electrodes, RF electrodes, and heater electrodes are embedded inside a ceramic substrate made of aluminum oxide or aluminum nitride, which has excellent heat resistance and corrosion resistance.

[0003] As an example of an electrostatic chuck assembly, Patent Document 1 (Japanese Patent Application Publication No. 2009-141204) discloses a substrate holder in which a first substrate made of a first ceramic sintered body and a second substrate made of a second ceramic sintered body are joined via a bonding film of a metal containing Al. This document discloses that the first substrate and the second substrate are joined via a bonding film of a metal containing Al by heat welding at a pressure of 4 to 20 MPa while heating the metal with the bonding film sandwiched between the first substrate and the second substrate, and it is stated that it is desirable for the metal containing Al to be an Al alloy containing Mg in the range of 0.5 to 5% by weight.

[0004] Incidentally, metal matrix composites (MMCs) have been attracting attention in recent years. Metal matrix composites are materials that combine a metal matrix composed of metals such as Al or metallic Si with ceramic reinforcing materials such as SiC or TiC, and are known to have advantages such as being lightweight, having high rigidity, high thermal conductivity, and low thermal expansion. Methods for joining metal matrix composites (MMCs) and ceramic materials have been proposed, and Patent Document 2 (Japanese Patent No. 4373538) discloses a joint in which an MMC containing an aluminum alloy as a matrix and a ceramic material are joined via a brazing material made of an Al alloy containing Mg. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2009-141204 [Patent Document 2] Patent No. 4373538 [Patent Document 3] Japanese Patent Publication No. 2006-196864 [Overview of the Initiative]

[0006] For use as a cooling plate in electrostatic chuck assemblies, MMC plates are desirable due to their advantages such as high thermal conductivity and low thermal expansion. Therefore, there is a need to improve the bonding strength in the joint between the MMC plate and the ceramic plate.

[0007] The present inventors have now discovered that by providing a predetermined bonding layer between an MMC plate and a ceramic plate, and by having an Al-enriched layer on the MMC plate extending to a predetermined depth (thickness) from the bonding interface between the bonding layer and the MMC plate, it is possible to provide a bonded body of a ceramic plate and an MMC plate with high bonding strength.

[0008] Therefore, an object of the present invention is to provide a joint of ceramic plates and MMC plates having high bonding strength.

[0009] The following aspects are provided according to this disclosure. [Aspect 1] Ceramic plate and An MMC plate is provided opposite one side of the ceramic plate and is composed of (i) Si, C and Ti, or (ii) Al, Si and C, A bonding layer provided between the ceramic plate and the MMC plate, which joins the ceramic plate and the MMC plate, comprising a bonding layer mainly composed of Al, The MMC plate is provided with a predetermined depth D from the bonding interface between the bonding layer and the MMC plate. Al The MMC plate has an Al-enriched layer in which Al is distributed at a higher concentration than in other parts of the plate, and the depth of the Al-enriched layer D Al A composite body in which the diameter is 40 μm or larger. [Aspect 2] The bonded body according to embodiment 1, wherein the metal matrix composite material (MMC) further comprises Al, or Al and N, in addition to Si, C, and Ti. [Aspect 3] The bonded body according to embodiment 1 or 2, wherein the metal matrix composite material (MMC) comprises Al, Si, and C. [Aspect 4] The bonded body according to any one of embodiments 1 to 3, wherein the bonding layer further contains Si as a minor component. [Aspect 5] The bonded body according to any one of embodiments 1 to 4, wherein the bonding layer further contains Mg as a minor component. [Aspect 6] The MMC plate extends to a predetermined depth D from the bonding interface between the bonding layer and the MMC plate. Mg The bonded body according to embodiment 5, having a Mg diffusion layer in which Mg originating from the bonding layer is diffused over the bonded layer. [Aspect 7] Depth D of the Al-enriched layer Al The depth D of the Mg diffusion layer Mg Larger than, that is, D Al >DMg The bonded body according to Aspect 6, which satisfies [Aspect 8] The bonded body according to any one of Aspects 1 to 7, wherein the ceramic plate contains aluminum oxide and / or aluminum nitride and has internal electrodes embedded therein. [Aspect 9] The bonded body according to any one of Aspects 1 to 8, wherein the bonding of the ceramic plate, the bonding layer, and the MMC plate is thermocompression bonding. [Aspect 10] The bonded body according to any one of Aspects 1 to 9, wherein the surface of the MMC plate on the bonding interface side has an arithmetic mean roughness Ra of 0.01 to 1.0 μm. [Aspect 11] The bonded body according to any one of Aspects 1 to 10, which exhibits a bonding strength of 200 MPa or more in a four-point bending test.

Brief Description of Drawings

[0010] [Figure 1] It is a schematic cross-sectional view showing an example of the bonded body according to the present invention. [Figure 2] It is a schematic cross-sectional view showing another example of the bonded body according to the present invention. [Figure 3A] An SEM image (Compo image) of a cross-section including the ceramic plate 12, the bonding interface 20, and the bonding layer 16 in the bonded body of Example 7, and Si, C, and Ti mapping images of the corresponding region are shown. [Figure 3B] An SEM image (Compo image) of a cross-section including the ceramic plate 12, the bonding interface 20, and the bonding layer 16 in the bonded body of Example 7, and O, Mg, and Al mapping images of the corresponding region are shown. [Figure 4A] An SEM image (Compo image) of a cross-section including the bonding layer 16, the bonding interface 22, and the MMC plate 14 in the bonded body of Example 7, and Si, C, and Ti mapping images of the corresponding region are shown. [Figure 4B] An SEM image (Compo image) of a cross-section including the bonding layer 16, the bonding interface 22, and the MMC plate 14 in the bonded body of Example 7, and O, Mg, and Al mapping images of the corresponding region are shown. [Figure 5A] SEM image (Compo image) of a cross-section including the bonding layer 16, the bonding interface 22, and the MMC plate 14 in the bonded body of Example 7, and a reduced version of the concentration scale of the Si, C, and Ti mapping images of the corresponding region are shown. [Figure 5B] SEM image (Compo image) of a cross-section including the bonding layer 16, the bonding interface 22, and the MMC plate 14 in the bonded body of Example 7, and a reduced version of the concentration scale of the O, Mg, and Al mapping images of the corresponding region are shown.

Embodiments for Carrying Out the Invention

[0011] zygote FIG. 1 shows an example of a bonded body according to the present invention. The bonded body 10 shown in FIG. 1 includes a ceramic plate 12, an MMC plate 14, and a bonding layer 16. Preferably, the ceramic plate 12 contains aluminum oxide and / or aluminum nitride, and an internal electrode 18 is embedded therein. The MMC plate 14 is a plate made of a metal matrix composite (MMC), and is provided facing one side of the ceramic plate 12. The metal matrix composite (MMC) contains (i) Si, C, and Ti, or (ii) Al, Si, and C. The bonding layer 16 is a layer that bonds the ceramic plate 12 and the MMC plate 14, and is provided between the ceramic plate 12 and the MMC plate 14. The bonding layer 16 mainly contains Al. As specifically shown in FIG. 2, the MMC plate 14 has an Al-enriched layer 26 in which Al is distributed at a higher concentration than other parts of the MMC plate 14 over a predetermined depth D from the bonding interface 22 between the bonding layer 16 and the MMC plate 14. The depth D of the Al-enriched layer 26 Al over which Al is distributed at a higher concentration than other parts of the MMC plate 14. AlThe thickness is 40 μm or more. In this way, by providing a predetermined bonding layer 16 between the MMC plate 14 and the ceramic plate 12, and by having an Al-enriched layer 26 extending to a predetermined depth (thickness) from the bonding interface 22 between the bonding layer 16 and the MMC plate 14, it is possible to provide a bonded body 10 of a ceramic plate 12 and an MMC plate 14 with high bonding strength. In other words, high bonding strength can be achieved between the MMC plate 14 and the ceramic plate 12 not only by employing a predetermined bonding layer 16, but also by providing an Al-enriched layer 26.

[0012] The ceramic plate 12 is a plate-shaped member containing a ceramic sintered body, and may have a similar structure to ceramic plates used in known ceramic susceptors (e.g., electrostatic chuck assemblies and ceramic heaters). Typically, an internal electrode 18 is embedded in the ceramic plate 12. The ceramic sintered body constituting the main part of the ceramic plate 12 other than the internal electrode 18 (i.e., the ceramic substrate) preferably contains aluminum oxide and / or aluminum nitride from the viewpoint of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics close to those of silicon. In addition to aluminum oxide and / or aluminum nitride, the ceramic sintered body constituting the ceramic plate 12 may contain additives such as MgO. In this case, the content of aluminum oxide and / or aluminum nitride in the ceramic sintered body constituting the ceramic plate 12 is typically 50 to 100% by mass, and the remainder may contain additives such as MgO. The thickness of the ceramic plate 12 can be the thickness of a general ceramic plate and is not particularly limited, but is typically 2 to 10 mm, and more typically 2 to 5 mm.

[0013] Examples of internal electrodes 18 embedded in the ceramic plate 12 include ESC electrodes, heater electrodes, and RF electrodes. Two types of internal electrodes 18 may be provided within the ceramic plate 12. ESC electrodes are an abbreviation for electrostatic chuck (ESC) electrodes and are also called electrostatic electrodes. ESC electrodes are preferably thin, circular electrodes with a diameter slightly smaller than the ceramic plate 12, and can be, for example, mesh electrodes made by weaving thin metal wires into a mesh to form a sheet. ESC electrodes may also be used as plasma electrodes. That is, by applying high frequency to the ESC electrodes, they can also be used as plasma electrodes, and film deposition can be performed by a plasma CVD process. When a voltage is applied by an external power supply, the ESC electrodes chucking the wafer placed on the surface of the ceramic plate 12 by the Johnson-Larbek force. Heater electrodes are not particularly limited, but for example, they can be conductive coils wired across the entire surface of the ceramic plate 12 in a single continuous line. The heater electrode generates heat when power is supplied from the heater power supply, heating the wafer placed on the surface of the ceramic plate 12. The heater electrode is not limited to a coil, but may also be, for example, a ribbon (a long, thin plate) or a mesh. The ribbon-shaped heater electrode may be formed by a printing method.

[0014] The MMC plate 14 is composed of a metal matrix composite (MMC). The MMC may be a known material in which a ceramic reinforcing material is composited in a metal matrix, and is not particularly limited. Examples of metal matrices include aluminum and metallic silicon. Examples of ceramic reinforcing materials include SiC and TiC. In a preferred embodiment of the present invention, the MMC may contain Si, C, and Ti. An example of an MMC containing Si, C, and Ti is a composite material containing 37 to 60% by mass of silicon carbide, and containing titanium silicon carbide and titanium carbide in amounts less than the silicon carbide content (by mass). Another example of an MMC containing Si, C, and Ti is a composite material containing 42 to 65% by mass of titanium silicide (TiSi2), and containing SiC, titanium silicon carbide, and titanium carbide in amounts less than the titanium silicide (TiSi2) content. The MMC containing Si, C, and Ti may further contain Al, or Al and N. In other words, MMC containing Si, C, and Ti may further contain Al, and Al may be contained in a form with N, such as AlN. The additional Al has the advantage of increasing the bonding strength. An example of MMC containing Si, C, Ti, Al, and N is a composite material containing 42-60 mass% titanium silicide and containing SiC, titanium silicon carbide, titanium carbide, alumina, and aluminum nitride in amounts less than the titanium silicide content (mass%). In another preferred embodiment of the present invention, the MMC contains Al, Si, and C. An example of MMC containing Al, Si, and C is a composite material containing 60-80 volume% SiC and containing aluminum in an amount less than the SiC content (vol%). The thickness of the MMC plate 14 is not particularly limited, but is typically 5-35 mm.

[0015] The surface of the MMC plate 14 on the side of the bonding interface 22 preferably has an arithmetic mean roughness Ra of 0.01 to 1.0 μm, and more preferably 0.05 to 0.70 μm. An arithmetic mean roughness Ra within the above range can more effectively increase the bonding strength. This is thought to be because not having too high an Ra improves the adhesion between the MMC plate 14 and the bonding layer 16, and not having too low an Ra provides an anchoring effect due to the surface roughness or irregularities of the MMC plate 14.

[0016] The bonding layer 16 is a metal layer mainly composed of Al. Preferably, the bonding layer 16 further contains Si and / or Mg as minor components, and more preferably contains Si, or Si and Mg as minor components. Here, "main component" means a component that accounts for 80% by weight or more of the bonding layer 16. "Minor component" means a component that is included in a lower content than the main component (excluding unavoidable impurities). Therefore, the bonding material constituting the bonding layer 16 is preferably a Si-containing Al alloy that does not contain Mg, or an Al alloy that contains Si and Mg. The Si content in this Al alloy is preferably 5 to 15% by weight. If Mg is included, the Mg content in the aluminum alloy is preferably 0.1 to 5.0% by weight. That is, the bonding layer 16 is preferably composed of an Al alloy containing Si: 5 to 15% by weight, Mg: 0.5 to 5.0% by weight, with the remainder being Al and unavoidable impurities. If Mg is not included, the bonding layer 16 is preferably composed of an Al alloy containing 5-15% by weight of Si, with the remainder being Al and unavoidable impurities.

[0017] The bonding interface 20 between the ceramic plate 12 and the bonding layer 16 may include a Mg-containing layer 24. The presence of the Mg-containing layer 24 at the bonding interface 20 is thought to improve the bonding strength between the ceramic plate 12 and the bonding layer 16, thereby achieving high bonding strength between the ceramic plate 12 and the MMC plate 14. The Mg-containing layer 24 is identified in the elemental mapping image obtained by EPMA (electron probe microanalyzer) as a layer containing a higher concentration of Mg at the bonding interface 20 than its surroundings. The Mg-containing layer 24 preferably further contains Al and O. In this case, the weight ratio of Al:Mg:O in the Mg-containing layer 24 is preferably in the range of 1:0.01~0.50:0.001~0.100, and more preferably in the range of 1:0.05~0.30:0.005~0.050. The weight ratio of Al:Mg:O can be measured by EPMA. The thickness of the Mg-containing layer 24 is preferably 1 to 10 μm, and more preferably 1 to 7 μm, from the viewpoint of improving bonding strength.

[0018] It is preferable that the ceramic plate 12, the bonding layer 16, and the MMC plate 14 are joined by hot pressure welding. Hot pressure welding is a method of joining two members by sandwiching a metal bonding film (corresponding to the bonding layer 16) between the two members to be joined and pressing the two members together while heating the metal bonding film to a temperature below the liquidus temperature (see Patent Document 1).

[0019] As shown in Figure 2, the MMC plate 14 extends from the bonding interface 22 between the bonding layer 16 and the MMC plate 14 to a predetermined depth D AlIt is preferable to have an Al-enriched layer 26 in which Al is distributed at a higher concentration than in other parts of the MMC plate 14. As mentioned above, by providing an Al-enriched layer 26, high bonding strength can be achieved between the MMC plate 14 and the ceramic plate 12. The Al-enriched layer 26 can typically be said to be a layer in which Al originating from the bonding layer 16 has diffused and become concentrated, but since the MMC plate 14 itself can contain Al, the origin of the Al in the Al-enriched layer 26 is not considered. As illustrated in Figure 5B described later, the Al-enriched layer 26 is identified in the Al elemental mapping image obtained by EPMA as a layer containing a higher concentration of Al (than other parts of the MMC plate 14) in the region adjacent to the bonding interface 22 of the MMC plate 14. That is, in the Al elemental mapping image, if pixels showing a high concentration of Al are distributed continuously from the bonding layer 16 to the region adjacent to the bonding interface 22 of the MMC plate 14, then the Al observed at a high concentration in the adjacent region of the MMC plate 14 can be said to be Al originating from the bonding layer 16. Thus, the Al-enriched layer 26 is identified. Depth D of the Al-enriched layer 26 Al The particle size is preferably 40 μm or larger, more preferably 40 to 600 μm, even more preferably 50 to 500 μm, and particularly preferably 250 to 500 μm.

[0020] As shown in Figure 2, the MMC plate 14, in addition to the Al-enriched layer 26, extends to a predetermined depth D from the bonding interface 22 between the bonding layer 16 and the MMC plate 14. MgThe MMC plate 14 may have a Mg diffusion layer 28 in which Mg originating from the bonding layer 16 is diffused over the entire surface. In this case, the Al-enriched layer 26 and the Mg diffusion layer 28 overlap at least partially (i.e., the MMC plate 14 has parts corresponding to both the Al-enriched layer 26 and the Mg diffusion layer 28). The Mg diffusion layer 28, along with the Al-enriched layer 26, is also considered to contribute to achieving high bonding strength. As illustrated in Figure 5B, described later, the Mg diffusion layer 28 is identified in the Mg elemental mapping image obtained by EPMA as a layer containing a higher concentration of Mg (than other areas of the MMC plate 14) in the region adjacent to the bonding interface 22 of the MMC plate 14. That is, in the Mg elemental mapping image, if pixels showing a high concentration of Mg are distributed continuously from the bonding layer 16 over the region adjacent to the bonding interface 22 of the MMC plate 14, the Mg observed in the above adjacent region of the MMC plate 14 can be said to be Mg originating from the bonding layer 16. In this way, the Mg diffusion layer 28 is identified. Depth D of Mg diffusion layer 28 Mg The depth of the Al-enriched layer 26 is preferably 10 to 300 μm, more preferably 20 to 200 μm, and even more preferably 90 to 180 μm. Typically, the depth D of the Al-enriched layer 26 Al The depth D of the Mg diffusion layer 28 Mg Larger than (i.e., D Al >D Mg (Meets the requirements).

[0021] The MMC plate 14 may have internal spaces such as flow channels through which a refrigerant can pass. This configuration makes the MMC plate 14 suitable as a cooling plate for an electrostatic chuck assembly.

[0022] The joint 10 exhibits a joint strength of preferably 200 MPa or more, more preferably 250 MPa or more, and even more preferably 300 MPa or more in a four-point bending test. The four-point bending test shall be performed according to the procedure and conditions disclosed in the examples described later, and the maximum bending stress obtained therefrom shall be adopted as the joint strength. Since a high joint strength is desired, the upper limit is not particularly limited, but it is typically 500 MPa or less, and more typically 450 MPa or less.

[0023] Manufacturing method of the joint The bonded body of the present invention may be manufactured by any method as long as a bonded body with a predetermined layer structure is obtained, but preferred manufacturing methods are described below.

[0024] First, a ceramic plate with embedded internal electrodes, an MMC plate, and a bonding layer are prepared. Details of each component are as described above. While known ceramic plates, MMC plates, and bonding layers can all be used, they may also be manufactured as appropriate based on known methods.

[0025] Next, ultrasonic cleaning is performed on each of the ceramic plate, MMC plate, and bonding layer using an organic solvent. Ultrasonic cleaning removes dirt adhering to the surface of each component, improving the bonding between each component and the bonding layer, and as a result, achieving high bonding strength. Preferred examples of organic solvents include acetone and isopropyl alcohol (IPA). Increasing the ultrasonic cleaning time can remove even more dirt, promoting the movement and diffusion of elements such as Mg and Al during hot-pressure welding. Therefore, by controlling the ultrasonic cleaning time, it is possible to control the formation or non-formation of the Mg-containing layer during subsequent hot-pressure welding, and to change the depth (thickness) of the Al-enriched layer and the Mg-containing layer. For example, by increasing the ultrasonic cleaning time, it is possible to form a Mg-containing layer or increase the depth of the Al-enriched layer and the Mg-containing layer. From the viewpoint of more effectively removing dirt adhering to the surface of each component, it is desirable to perform both ultrasonic cleaning using acetone and ultrasonic cleaning using isopropyl alcohol (IPA). It is preferable that the ceramic plates and MMC plates that have been ultrasonically cleaned be further purified by running water with pure water, blowing with N2 gas, wiping with a wipe sheet impregnated with an organic solvent (such as IPA), and drying. Furthermore, it is preferable that the bonding layer that has been ultrasonically cleaned be further purified by blowing with N2 gas.

[0026] A joint is then fabricated by hot-pressure welding using the cleaned ceramic plate, MMC plate, and bonding layer. For example, the bonding layer can be placed between the ceramic plate and the MMC plate, and the joint can be joined to the ceramic plate and the MMC plate via the bonding layer by hot-pressure welding at a pressure of 4 MPa to 30 MPa while heating to a temperature below the liquidus temperature of the bonding material film. The hot-pressure welding temperature is preferably below the liquidus temperature of the bonding layer and at least about 30°C lower than the solidus temperature. For example, the liquidus temperature of an aluminum alloy containing Si: 10 wt% and Mg: 1 wt% is about 590°C, and the solidus temperature is about 560°C. Therefore, in this case, a hot-pressure welding temperature in the range of about 520°C to less than about 540°C is desirable. In this way, a joint of the present invention can be obtained in which the ceramic plate and the MMC plate are joined via the bonding layer. [Examples]

[0027] The present invention will be further described in detail by the following examples. However, the present invention is not limited to the following examples.

[0028] Examples 1-9 (1) Preparation of ceramic plates A disc-shaped aluminum oxide sintered body (thickness: 5 mm, diameter: 300 mm) with embedded ESC electrodes was fabricated as a ceramic plate in the following manner. First, two disc-shaped alumina green sheets were prepared. ESC electrodes were formed on one surface of the first green sheet by screen printing, while heater electrodes were formed on one surface of the second green sheet by screen printing. Next, another alumina green sheet (hereinafter referred to as the third green sheet) was laminated onto the surface of the first green sheet where the ESC electrodes were formed, and the second green sheet was laminated on top of that so that the heater electrodes were in contact with the third green sheet. The resulting laminate was fired by a hot press to obtain a ceramic sintered body with embedded ESC electrodes and heater electrodes. The shape and thickness of the obtained ceramic sintered body were adjusted by grinding, blasting, etc., on both sides to obtain a flat electrostatic chuck as a ceramic plate. The specific manufacturing conditions for this electrostatic chuck were set with reference to the conditions described in Japanese Patent Application Publication No. 2006-196864.

[0029] (2) Preparation of MMC plates As an MMC plate, a plate containing Si, C, and Ti (SiSiCTi plate) was prepared as follows. First, as raw materials, SiC raw material (commercially available product with a purity of 97% or higher and an average particle size of 15.5 μm), metallic Si raw material (commercially available product with a purity of 97% or higher and an average particle size of 9.0 μm), and metallic Ti raw material (commercially available product with a purity of 99.5% or higher and an average particle size of 31.1 μm) were prepared. The SiC raw material, metallic Si raw material, and metallic Ti raw material were weighed to a blending ratio of SiC: 49.5 mass%, Si: 20.0 mass%, and Ti: 30.5 mass%, and placed in a nylon pot with isopropyl alcohol as a solvent. Wet mixing was performed for 4 hours using a nylon ball with an iron core and a diameter of 10 mm. The resulting slurry was removed, dried at 110°C in a nitrogen stream, and then passed through a 30-mesh sieve to obtain a blended powder. The blended powder was subjected to a pressure of 200 kgf / cm². 2Uniaxial pressure molding was performed to produce a disc-shaped molded body with a diameter of approximately 50 mm and a thickness of approximately 17 mm, which was then placed in a graphite mold for firing. An MMC plate was obtained by hot-press firing of the disc-shaped molded body. This hot-press firing was performed under a vacuum atmosphere at 200 kgf / cm². 2 This was carried out by applying press pressure while maintaining a firing temperature (maximum temperature) of 1400°C for 4 hours.

[0030] The arithmetic mean roughness Ra of the surface to which the bonding layer of the prepared MMC plate was to be bonded was measured using a stylus-type surface roughness measuring instrument, in accordance with JIS B 0601-2001. The results are shown in Table 1.

[0031] (3) Preparation of the bonding layer A 0.12 mm thick Si and Mg-containing Al alloy sheet (alloy composition: Si: 10 wt%, Mg: 1 wt%, remainder: Al and unavoidable impurities) was prepared to serve as the bonding layer.

[0032] (4) Cleaning process The following cleaning steps (i) to (vi) were performed sequentially on the ceramic plate and the MMC plate, while only the following cleaning steps (i), (ii), and (iv) were performed sequentially on the Si and Mg-containing Al alloy sheet. <Purification Process> (i) Ultrasonic cleaning using acetone (not performed in Example 9) (ii) Ultrasonic cleaning using isopropyl alcohol (IPA) (not performed in Example 9) (iii) Washing with pure water (iv) Blowing with N2 gas (v) Dry at 120°C for 10 minutes.

[0033] In this experiment, the total cleaning time for (i) ultrasonic cleaning using acetone and (ii) ultrasonic cleaning using isopropyl alcohol (IPA), i.e., the total ultrasonic cleaning time with organic solvents, was varied for each experimental example as shown in Table 1. Therefore, as stated above, ultrasonic cleaning (i) and (ii) were not performed in Example 9.

[0034] (5) Thermocompression Bonding Thermocompression bonding was performed as follows using the cleaned ceramic plate, MMC plate, and bonding sheet. That is, a bonding sheet was sandwiched as a bonding layer between the ceramic plate and the MMC plate, and heated to 530 °C (a temperature lower than the liquidus temperature of the Si- and Mg-containing Al alloy and higher than a temperature about 30 °C lower than the solidus temperature) while applying a pressure of 20 MPa in a vacuum for thermocompression bonding, thereby joining the ceramic plate, the bonding sheet (bonding layer), and the MMC plate to each other. Thus, a joined body in which the ceramic plate and the MMC plate were joined via the bonding layer was obtained.

[0035] (6) Evaluation of the Joined Body The following evaluations were performed on the fabricated joined body.

[0036] <Obtaining an elemental mapping image by EPMA> After cutting out a cross section of the obtained joined body and performing mirror polishing, flat ion milling with Ar ions was carried out to obtain an observation cross section. A 75 μm × 75 μm region including the ceramic plate 12, the bonding interface 20, and the bonding layer 16 in the obtained observation cross section was observed with a SEM (scanning electron microscope), and elemental analysis of the region was performed by EPMA (manufactured by JEOL Ltd.) under measurement conditions of an acceleration voltage of 15 kV to obtain elemental mapping images of Si, C, Ti, O, Mg, and Al. FIGS. 3A and 3B show a SEM image (Compo image) of a cross section including the ceramic plate 12, the bonding interface 20, and the bonding layer 16 in the joined body of Example 7 and elemental mapping images of various elements in the corresponding region. As a result, as shown in Table 1 and FIGS. 3A and 3B, in the joined bodies of Examples 1 to 7, a Mg-containing layer 24 containing Mg at a higher concentration than its surroundings was observed at the bonding interface 20, and it was also confirmed that this Mg-containing layer 24 further contained Al and O. On the other hand, in the joined bodies of Examples 8 and 9 (comparative examples), such a Mg-containing layer was not observed.

[0037] Also, for a 75 μm × 75 μm region including the bonding layer 16, the bonding interface 22, and the bonding interface 22 between the MMC plate 14 in the obtained observation cross-section, SEM observation and EPMA elemental analysis were performed in the same manner as above. Figures 4A and 4B show SEM images (Compo images) of a cross-section including the bonding layer 16, the bonding interface 22, and the MMC plate 14 in the bonded body of Example 7 and various elemental mapping images of the corresponding regions. As a result, in all of the bonded bodies of Examples 1 to 9, as shown in Figures 4A and 4B, a microstructure having TiC particles (see the black particles in the figure), a TiSi2 matrix phase (see the gray portion in the figure), and SiC particles (see the white particles in the figure) was observed in the MMC plate 14 (SiSiCTi plate). Further, in the bonded bodies of Examples 1 to 7, it was also confirmed that Mg and Al were diffused in the SiSiCTi constituting the MMC plate 14.

[0038] Furthermore, for a wider cross-sectional region of 300 μm × 300 μm including the bonding layer 16, the bonding interface 22, and the bonding interface 22 between the MMC plate 14, SEM observation and EPMA elemental analysis were performed in the same manner as above, except that the magnification was lowered and the concentration scale was reduced. Figures 5A and 5B show a version with the concentration scale reduced of the SEM image (Compo image) of a cross-section including the bonding layer 16, the bonding interface 22, and the MMC plate 14 in the bonded body of Example 7 and various elemental mapping images of the corresponding regions. As a result, in the bonded bodies of Examples 1 to 9, the presence of an Al enrichment layer 26 and a Mg diffusion layer 28 in which Al and Mg derived from the bonding layer 16 were respectively diffused over the depth direction of the MMC plate 14 from the bonding interface 22 was confirmed within the MMC plate 14. The depth D of the Al enrichment layer 26 from the bonding interface 22 Al and the depth D of the Mg diffusion layer 28 from the bonding interface 22 Mg were measured, and values as shown in Table 1 were obtained.

[0039] <Weight ratio of Al:Mg:O in the Mg-containing layer> From the EPMA measurement results, semi-quantitative values ​​of each element were calculated for each pixel corresponding to 0.24 μm × 0.24 μm, and the weight ratio of Al:Mg:O was calculated by calculating the weight ratio from the average value of 300 pixels. As a result, the weight ratios of Al:Mg:O in the Mg-containing layer were 1:0.134:0.0238 (Example 1), 1:0.413:0.0961 (Example 2), 1:0.253:0.0479 (Example 3), 1:0.250:0.0532 (Example 4), 1:0.233:0.0196 (Example 5), 1:0.018:0.0099 (Example 6), and 1:0.141:0.0321 (Example 7).

[0040] <Joining strength> From the obtained joint, a long specimen was cut out so that the joint layer was located in the center in the longitudinal direction, and the surface of the specimen was ground to prepare a test piece with dimensions of 1.5 mm × 2.0 mm × 20 mm. A four-point bending test was performed on this test piece with the joint interface as the center, under the conditions of a lower span of 15 mm, an upper span of 5 mm, and a crosshead speed of 0.5 mm / min, and the maximum bending stress (MPa) obtained was defined as the joint strength. The results are shown in Table 1.

[0041] [Table 1]

[0042] Examples 10-12 The joint was fabricated and evaluated in the same manner as in Example 1, except that i) a plate containing Si, C, Ti, and Al (SiSiCTi+Al plate) prepared as described below was used as the MMC plate, and ii) the ultrasonic cleaning time with organic solvent was as shown in Table 2. The results are shown in Table 2.

[0043] (Fabrication of MMC plates) As an MMC plate, a plate containing Si, C, Ti, and Al (however, Al may be in the form of AlN) was prepared as follows. First, as raw materials, SiC raw material (commercially available product with a purity of 97% or higher and an average particle size of 15.5 μm), metallic Si raw material (commercially available product with a purity of 97% or higher and an average particle size of 9.0 μm), metallic Ti raw material (commercially available product with a purity of 99.5% or higher and an average particle size of 31.1 μm), and AlN raw material (commercially available product with a purity of 97% or higher and an average particle size of 1.1 μm) were prepared. The SiC raw material, metallic Si raw material, metallic Ti raw material, and AlN raw material were weighed to the following proportions: SiC: 49.5% by mass, Si: 10.0% by mass, Ti: 30.5% by mass, and AlN: 10.0% by mass. These were then placed in a nylon pot with isopropyl alcohol as a solvent and wet-mixed for 4 hours using a nylon ball with an iron core and a diameter of 10 mm. The obtained slurry was removed, dried at 110°C in a nitrogen stream, and then passed through a 30-mesh sieve to obtain a compound powder. The compound powder was then subjected to a pressure of 200 kgf / cm³. 2 Uniaxial pressure molding was performed to produce a disc-shaped molded body with a diameter of approximately 50 mm and a thickness of approximately 17 mm, which was then placed in a graphite mold for firing. An MMC plate was obtained by hot-press firing of the disc-shaped molded body. This hot-press firing was performed under a vacuum atmosphere at 200 kgf / cm². 2 This was carried out by applying press pressure while maintaining a firing temperature (maximum temperature) of 1400°C for 4 hours.

[0044] Examples 13-18 The joint was fabricated and evaluated in the same manner as in Example 1, except that i) an Al-Si bond layer without Mg prepared as described below was used, ii) hot pressure welding was performed as described below, and iii) the ultrasonic cleaning time with an organic solvent was as shown in Table 2. The results are shown in Table 2.

[0045] (Preparation of the bonding layer) A 0.12 mm thick Si and Al alloy sheet (alloy composition: Si: 10 wt%, remainder: Al and unavoidable impurities) was prepared to serve as the bonding layer.

[0046] (thermal pressure welding) The following thermal pressure welding was performed using cleaned ceramic plates, MMC plates, and bonding sheets. Specifically, a bonding sheet was placed between the ceramic plate and the MMC plate as a bonding layer, and the two were heated to 560°C (a temperature below the liquidus temperature of Si and Al alloys, and at least 30°C lower than the solidus temperature) while thermal pressure welding was performed under a pressure of 20 MPa in a vacuum, thereby joining the ceramic plate, bonding sheet (bonding layer), and MMC plate to each other. In this way, a bonded body was obtained in which the ceramic plate and the MMC plate were joined via the bonding layer.

[0047] Examples 19-21 The joint was fabricated and evaluated in the same manner as in Example 13, except that i) a plate containing Si, C, Ti, and Al(AlN) prepared in the same manner as in Example 10 (SiSiCTi+Al(AlN) plate) was used as the MMC plate, and ii) the ultrasonic cleaning time with the organic solvent was as shown in Table 2. The results are shown in Table 2.

[0048] Examples 22-24 The joint was fabricated and evaluated in the same manner as in Example 13, except that i) a plate containing Si, C, and Al (AlSiC plate) prepared as described below was used as the MMC plate, and ii) the ultrasonic cleaning time with an organic solvent was as shown in Table 2. The results are shown in Table 2.

[0049] (Fabrication of MMC plates) As an MMC plate, a plate containing Si, C, and Al was prepared as follows. First, 5 parts by mass of PVB (polyvinyl butyral) and 5 parts by mass of colloidal silica were added to 100 parts by mass of SiC raw material as raw material powder, and a porous ceramic molded body (preform) was prepared by pressing the resulting mixture. The obtained preform was preheated to 700°C, and the preheated preform was placed inside the mold of a pressurizing device. Next, molten aluminum alloy (AC3A) at 750°C was poured into the mold, and a pressure of 30 MPa was applied to permeate the molten aluminum alloy into the preform. The permeation treatment was carried out for 10 minutes. After that, the composite material in which the aluminum alloy had permeated the SiC was removed from the mold, and excess Al alloy adhering to the surrounding area of ​​the composite material was ground off to obtain an MMC plate made of Al-SiC composite material with SiC at 70 volume%.

[0050] Examples 25-27 The joint was fabricated and evaluated in the same manner as in Example 19, except that i) an aluminum nitride sintered body prepared as described below was used as the ceramic plate, and ii) the ultrasonic cleaning time with an organic solvent was as shown in Table 2. The results are shown in Table 2.

[0051] (Ceramic plate fabrication) A disc-shaped aluminum nitride sintered body (thickness: 5 mm, diameter: 300 mm) with embedded ESC electrodes was fabricated as a ceramic plate in the following manner. First, two disc-shaped aluminum nitride green sheets were prepared. ESC electrodes were formed on one surface of the first green sheet by screen printing, while heater electrodes were formed on one surface of the second green sheet by screen printing. Next, another aluminum nitride green sheet (hereinafter referred to as the third green sheet) was laminated onto the surface of the first green sheet where the ESC electrodes were formed, and the second green sheet was laminated on top of that so that the heater electrodes were in contact with the third green sheet. The resulting laminate was fired by a hot press to obtain a ceramic sintered body with embedded ESC electrodes and heater electrodes. The shape and thickness of the obtained ceramic sintered body were adjusted by grinding, blasting, etc., on both sides to obtain a flat electrostatic chuck as a ceramic plate.

[0052] [Table 2] [Explanation of symbols]

[0053] 10 zygote 12 Ceramic Plates 14 MMC Plates 16 Bonding layer 18 Internal electrode 20,22 Joint interface 24 Mg-containing layer 26 Al enriched layer 28 Mg diffusion layer

Claims

1. Ceramic plate and A metal matrix composite (MMC) plate is provided opposite one side of the ceramic plate and is composed of (i) Si, C and Ti, or (ii) Al, Si and C. A bonding layer provided between the ceramic plate and the MMC plate, which joins the ceramic plate and the MMC plate, comprising a bonding layer mainly composed of Al, The MMC plate is provided with a predetermined depth D from the bonding interface between the bonding layer and the MMC plate. Ａｌ The MMC plate has an Al-enriched layer in which Al is distributed at a higher concentration than in other parts of the plate, and the depth of the Al-enriched layer D Ａｌ A composite body in which the diameter is 40 μm or larger.

2. The bonded body according to claim 1, wherein the metal matrix composite material (MMC) further comprises Al, or Al and N, in addition to Si, C, and Ti.

3. The bonded body according to claim 1, wherein the metal matrix composite material (MMC) comprises Al, Si, and C.

4. The bonded body according to claim 1, wherein the bonding layer further contains Si as a minor component.

5. The bonded body according to claim 4, wherein the bonding layer further contains Mg as a minor component.

6. The MMC plate extends to a predetermined depth D from the bonding interface between the bonding layer and the MMC plate. Ｍｇ The bonded body according to claim 5, further comprising a Mg diffusion layer in which Mg originating from the bonding layer is diffused over the bonded layer.

7. Depth D of the Al-enriched layer Ａｌ The depth D of the Mg diffusion layer Ｍｇ Larger than, i.e., D Ａｌ >D Ｍｇ The joint according to claim 6, satisfying the requirements.

8. The joint according to any one of claims 1 to 7, wherein the ceramic plate contains aluminum oxide and / or aluminum nitride, and has an embedded internal electrode.

9. The bonded body according to any one of claims 1 to 7, wherein the bonding of the ceramic plate, the bonding layer, and the MMC plate is performed by hot pressure welding.

10. The bonded body according to any one of claims 1 to 7, wherein the surface of the MMC plate on the bonding interface side has an arithmetic mean roughness Ra of 0.01 to 1.0 μm.

11. A joint according to any one of claims 1 to 7, which exhibits a joint strength of 200 MPa or more in a four-point bending test.

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