Bonded body

Abstract

The present invention provides a bonded body of a ceramic plate and an MMC plate, the bonded body having high bonding strength. This bonded body includes: a ceramic plate; an MMC plate which is provided so as to face one side of the ceramic plate and is composed of a metal matrix composite (MMC) containing (i) Si, C, and Ti, or (ii) Al, Si, and C; and a bonding layer which is provided between the ceramic plate and the MMC plate, and bonds the ceramic plate and the MMC plate to each other, the bonding layer containing Al as a main component. The MMC plate has an Al-concentrated layer, in which Al is distributed at a higher concentration than the other parts of the MMC plate, over a specific depth DAl from the bonding interface between the bonding layer and the MMC plate, and the depth DAl of the Al-concentrated layer is 40 μm or more.

Description

zygote

[0001] The present disclosure relates to conjugates.

[0002] Circuit formation in semiconductor device manufacturing is commonly performed using plasma etching. Plasma etching is performed by introducing an inert gas into a vacuum chamber in a plasma etching apparatus to generate plasma. The plasma etching apparatus is equipped with an electrostatic chuck assembly that functions as a susceptor on which a wafer to be etched is placed. A typical electrostatic chuck assembly includes 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 attracted to the electrode-embedded ceramic plate, and plasma etching is performed while the wafer is fixed to the electrostatic chuck assembly. Meanwhile, the cooling plate is attached to the bottom surface of the electrode-embedded ceramic plate and is configured to remove heat generated by the wafer during plasma etching. An electrode-embedded ceramic plate typically has an internal electrode, such as an electrostatic chuck (ESC) electrode, RF electrode, or heater electrode, embedded within a ceramic base made of a material such as aluminum oxide or aluminum nitride, which has excellent heat and corrosion resistance.

[0003] As an example of an electrostatic chuck assembly, Patent Document 1 (JP 2009-141204 A) discloses a substrate holder in which a first base made of a first ceramic sintered body and a second base made of a second ceramic sintered body are bonded via a bonding film made of a metal containing Al. This document discloses that the first base and the second base are bonded via the bonding film by sandwiching a bonding film made of a metal containing Al between the first and second bases and heating the metal while thermocompressing the metal at a pressure of 4 to 20 MPa, and it is stated that the metal containing Al is preferably an Al alloy containing 0.5 to 5 wt % of Mg.

[0004] Recently, metal matrix composites (MMCs) have been attracting attention. Metal matrix composites are materials in which a ceramic reinforcing material such as SiC or TiC is combined with a metal matrix composed of a metal such as Al or metallic Si. These materials are known to have advantages such as light weight, high rigidity, high thermal conductivity, and low thermal expansion. A method for joining a metal matrix composite (MMC) to a ceramic material has been proposed, and Patent Document 2 (Japanese Patent No. 4373538) discloses a joined body in which an MMC containing an aluminum alloy as a matrix and a ceramic material are joined via a brazing filler metal composed of an Al alloy containing Mg.

[0005] Japanese Patent Publication No. 2009-141204 Japanese Patent No. 4373538 Japanese Patent Publication No. 2006-196864

[0006] It is desirable to use an MMC plate as the cooling plate of an electrostatic chuck assembly because of its advantages of high thermal conductivity, low thermal expansion, etc. Therefore, there is a demand for improving the bonding strength of the bonded body between the MMC plate and the ceramic plate.

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

[0008] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a bonded assembly of a ceramic plate and an MMC plate having high bonding strength.

[0009] According to the present disclosure, the following aspects are provided: [Aspect 1] A ceramic plate, an MMC plate provided opposite one side of the ceramic plate and made of a metal matrix composite (MMC) containing (i) Si, C, and Ti, or (ii) Al, Si, and C, and a bonding layer provided between the ceramic plate and the MMC plate, bonding the ceramic plate and the MMC plate, the bonding layer containing Al as a main component, wherein 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 MMC plate, and the Al-enriched layer has a depth D Ａｌ A joined body having a thickness of 40 μm or more. [Aspect 2] The joined body according to Aspect 1, wherein the metal matrix composite (MMC) further contains Al, or Al and N, in addition to Si, C, and Ti. [Aspect 3] The joined body according to Aspect 1 or 2, wherein the metal matrix composite (MMC) contains Al, Si, and C. [Aspect 4] The joined body according to any one of Aspects 1 to 3, wherein the bonding layer further contains Si as a minor component. [Aspect 5] The joined body according to any one of Aspects 1 to 4, wherein the bonding layer further contains Mg as a minor component. [Aspect 6] The MMC plate has a thickness of 40 μm or more from the bonding interface between the bonding layer and the MMC plate at a predetermined depth D Ｍｇ The joined body according to Aspect 5, further comprising an Mg diffusion layer in which Mg originating from the joining layer is diffused throughout the entire Al-enriched layer. Ａｌ is the depth D of the Mg diffusion layer Ｍｇ is greater than D Ａｌ >D ＭｇThe joined body according to Aspect 6, which satisfies the above. [Aspect 8] The joined body according to any one of Aspects 1 to 7, wherein the ceramic plate contains aluminum oxide and / or aluminum nitride, and has an internal electrode embedded therein. [Aspect 9] The joined body according to any one of Aspects 1 to 8, wherein the ceramic plate, the bonding layer, and the MMC plate are bonded by thermocompression welding. [Aspect 10] The joined 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 joined 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.

[0010] 1 is a schematic cross-sectional view showing an example of a bonded body according to the present invention; 2 is a schematic cross-sectional view showing another example of a bonded body according to the present invention; 3 is 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; 4 is 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; 5 is 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; 6 is 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; 1 shows 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 a reduced-concentration-scale version of the Si, C, and Ti mapping images of the corresponding region. 1 shows 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 a reduced-concentration-scale version of the O, Mg, and Al mapping images of the corresponding region.

[0011] FIG. 1 shows an example of a joined body according to the present invention. The joined 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 includes 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) material and is provided opposite one side of the ceramic plate 12. The metal matrix composite (MMC) material includes (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 contains Al as a main component. As shown more specifically in FIG. 2, the MMC plate 14 is formed at a predetermined depth D from a bonding interface 22 between the bonding layer 16 and the MMC plate 14. Ａｌ The MMC plate 14 has an Al-enriched layer 26 in which Al is distributed at a higher concentration than in other parts of the MMC plate 14. Ａｌ 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 making the MMC plate 14 have an Al-enriched layer 26 extending from the bonding interface 22 between the bonding layer 16 and the MMC plate 14 to a predetermined depth (thickness), it is possible to provide a bonded body 10 of the ceramic plate 12 and the MMC plate 14 with high bonding strength. In other words, by not only employing the predetermined bonding layer 16 but also providing the Al-enriched layer 26, it is possible to achieve high bonding strength between the MMC plate 14 and the ceramic plate 12.

[0012] The ceramic plate 12 is a plate-shaped member including a ceramic sintered body and may have a configuration similar to that of ceramic plates used in known ceramic susceptors (e.g., electrostatic chuck assemblies, ceramic heaters, etc.). Typically, an internal electrode 18 is embedded in the ceramic plate 12. The ceramic sintered body constituting the main portion 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 viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon. The ceramic sintered body constituting the ceramic plate 12 may contain additives such as MgO in addition to aluminum oxide and / or aluminum nitride. In this case, the content of aluminum oxide and / or aluminum nitride in the ceramic sintered body constituting the ceramic plate 12 may be typically 50 to 100 mass %, with the remainder containing additives such as MgO. The thickness of the ceramic plate 12 may be the same as that of a typical ceramic plate and is not particularly limited, but may typically be 2 to 10 mm, more typically 2 to 5 mm.

[0013] Examples of the internal electrode 18 embedded in the ceramic plate 12 include an ESC electrode, a heater electrode, and an RF electrode. Two types of internal electrodes 18 may be provided within the ceramic plate 12. The ESC electrode is an abbreviation for electrostatic chuck (ESC) electrode and is also referred to as an electrostatic electrode. The ESC electrode is preferably a circular thin-layer electrode with a diameter slightly smaller than the ceramic plate 12, and may be, for example, a mesh electrode formed by weaving thin metal wires into a sheet. The ESC electrode may also be used as a plasma electrode. That is, by applying high frequency to the ESC electrode, the ESC electrode can also be used as a plasma electrode, allowing for film formation using a plasma CVD process. When a voltage is applied from an external power source, the ESC electrode chucks a wafer placed on the surface of the ceramic plate 12 by the Johnsen-Rahbek force. The heater electrode is not particularly limited, but may be, for example, a conductive coil wired in a single stroke across the entire surface of the ceramic plate 12. When power is supplied from the heater power supply, the heater electrode generates heat and heats the wafer placed on the surface of the ceramic plate 12. The heater electrode is not limited to a coil, but may be, for example, a ribbon (a long, thin plate) or a mesh. A ribbon-shaped heater electrode may be formed by a printing method.

[0014] The MMC plate 14 is made of a metal matrix composite (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 the metal matrix include aluminum and metallic silicon. Examples of the ceramic reinforcing material 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 mass % of silicon carbide, and containing titanium silicon carbide and titanium carbide in amounts (mass %) less than the silicon carbide content. Another example of an MMC containing Si, C, and Ti is titanium silicide (TiSi ２) in an amount of 42 to 65 mass %, and SiC, titanium silicon carbide, and titanium carbide are each replaced with titanium silicide (TiSi ２ Examples of suitable MMCs include composite materials containing Si, C, and Ti in amounts less than the total mass % of the titanium silicide (SiC), SiC, and Ti. MMCs containing Si, C, and Ti may further contain Al, or Al and N. That is, MMCs containing Si, C, and Ti may further contain Al, and Al may be contained in a form accompanied by N, such as AlN. The additional inclusion of Al has the advantage of increasing bonding strength. Examples of MMCs containing Si, C, Ti, Al, and N include composite materials containing 42 to 60 mass % of titanium silicide and SiC, titanium silicon carbide, titanium carbide, alumina, and aluminum nitride in amounts less than the total mass % of titanium silicide (SiC). In another preferred embodiment of the present invention, the MMC contains Al, Si, and C. Examples of MMCs containing Al, Si, and C include composite materials containing 60 to 80 volume % of SiC and aluminum in an amount less than the total volume % of SiC (SiC). The thickness of the MMC plate 14 is not particularly limited, but is typically 5 to 35 mm.

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

[0016] The bonding layer 16 is a metal layer containing Al as its primary component. The bonding layer 16 preferably further contains Si and / or Mg as secondary components, more preferably Si or Si and Mg as secondary components. Here, "primary component" refers to a component that accounts for 80% or more by weight of the bonding layer 16. "Secondary component" refers to a component that is contained in a lower amount than the primary 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 contained, 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 5 to 15% by weight of Si and 0.5 to 5.0% by weight of Mg, with the remainder being Al alloy containing Al and unavoidable impurities. If no Mg is contained, the bonding layer 16 preferably contains 5 to 15 wt % Si, with the remainder being an Al alloy containing Al and unavoidable impurities.

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

[0018] The ceramic plate 12, the bonding layer 16, and the MMC plate 14 are preferably bonded by thermocompression bonding. Thermocompression bonding is a method in which a metal bonding film (corresponding to the bonding layer 16) is sandwiched between two members to be bonded, and the two members are pressure-bonded while being heated to a temperature below the liquidus temperature of the metal bonding film (see Patent Document 1).

[0019] As shown in FIG. 2, the MMC plate 14 is formed at a predetermined depth D from the bonding interface 22 between the bonding layer 16 and the MMC plate 14. Ａｌ Preferably, the MMC plate 14 has an Al-enriched layer 26 in which Al is distributed at a higher concentration throughout the MMC plate 14 than in other portions of the MMC plate 14. As described above, providing the Al-enriched layer 26 can achieve high bonding strength between the MMC plate 14 and the ceramic plate 12. The Al-enriched layer 26 is typically a layer enriched by diffusion of Al originating from the bonding layer 16. However, since the MMC plate 14 itself may contain Al, the origin of the Al in the Al-enriched layer 26 is not important. As illustrated in FIG. 5B (described later), the Al-enriched layer 26 is identified as a layer containing Al at a higher concentration (than other regions of the MMC plate 14) observed in a region adjacent to the bonding interface 22 of the MMC plate 14 in an Al elemental mapping image acquired by EPMA. That is, when pixels showing a high concentration of Al are distributed continuously from the bonding layer 16 throughout a region adjacent to the bonding interface 22 of the MMC plate 14 in the Al elemental mapping image, 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. In this way, the Al-enriched layer 26 is identified. Ａｌ is preferably 40 μm or more, more preferably 40 to 600 μm, even more preferably 50 to 500 μm, and particularly preferably 250 to 500 μm.

[0020] As shown in FIG. 2 , in addition to the Al-enriched layer 26 , the MMC plate 14 has a predetermined depth D ＭｇThe MMC plate 14 may have an Mg diffusion layer 28 in which Mg derived from the bonding layer 16 is diffused throughout the entire MMC plate 14. In this case, the Al-enriched layer 26 and the Mg diffusion layer 28 at least partially overlap (i.e., the MMC plate 14 has portions corresponding to both the Al-enriched layer 26 and the Mg diffusion layer 28). It is believed that the Mg diffusion layer 28, together with the Al-enriched layer 26, can contribute to achieving high bonding strength. As illustrated in FIG. 5B , the Mg diffusion layer 28 is identified as a layer containing a higher concentration of Mg (than other regions of the MMC plate 14) observed in a region adjacent to the bonding interface 22 of the MMC plate 14 in an Mg elemental mapping image acquired by EPMA. That is, when pixels showing a high concentration of Mg are distributed continuously from the bonding layer 16 throughout a region adjacent to the bonding interface 22 of the MMC plate 14 in the Mg elemental mapping image, it can be said that the Mg observed in high concentration in the adjacent region of the MMC plate 14 is Mg derived from the bonding layer 16. In this way, the Mg diffusion layer 28 is identified. Ｍｇ The depth D 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. Ａｌ is the depth D of the Mg diffusion layer 28 Ｍｇ is greater than (i.e., D Ａｌ >D Ｍｇ satisfy).

[0021] The MMC plate 14 may have an internal space such as a flow path through which a coolant can flow, thereby making the MMC plate 14 suitable for use as a cooling plate for an electrostatic chuck assembly.

[0022] In a four-point bending test, the bonded body 10 preferably exhibits a bond strength of 200 MPa or more, more preferably 250 MPa or more, and even more preferably 300 MPa or more. The four-point bending test is performed according to the procedures and conditions disclosed in the Examples described below, and the maximum bending stress obtained therefrom is used as the bond strength. Since a high bond strength is desired, the upper limit is not particularly limited, but is typically 500 MPa or less, more typically 450 MPa or less.

[0023] Method for Producing the Bonded Body The bonded body of the present invention may be produced by any method as long as it can produce a bonded body having a predetermined layer structure, but a preferred production method will be described below.

[0024] First, a ceramic plate with an embedded internal electrode, an MMC plate, and a bonding layer are prepared. Details of each component are as described above. The ceramic plate, the MMC plate, and the bonding layer may be any known material, or may be manufactured by a known method.

[0025] Next, the ceramic plate, MMC plate, and bonding layer are each subjected to ultrasonic cleaning using an organic solvent. Ultrasonic cleaning can remove contaminants adhering to the surfaces of each component, improving the bonding between each component and the bonding layer, resulting in high bonding strength. Preferred examples of organic solvents include acetone and isopropyl alcohol (IPA). Increasing the ultrasonic cleaning time can further remove contaminants and promote the migration and diffusion of elements such as Mg and Al during thermocompression bonding. Therefore, by controlling the ultrasonic cleaning time, it is possible to control the formation / non-formation of an Mg-containing layer in the subsequent thermocompression bonding and to change the depth (thickness) of the Al-enriched layer and the depth (thickness) of the Mg-containing layer. For example, increasing the ultrasonic cleaning time can form an Mg-containing layer or increase the depth of the Al-enriched layer and the Mg-containing layer. From the perspective of more effectively removing contaminants adhering to the surfaces of each component, it is desirable to perform both ultrasonic cleaning using acetone and ultrasonic cleaning using isopropyl alcohol (IPA). The ceramic plate and MMC plate that have been subjected to ultrasonic cleaning are then washed with running pure water and N ２ It is preferable to further clean the bonding layer by blowing with gas, wiping with a wipe sheet impregnated with an organic solvent (e.g., IPA), and drying. ２ Preferably, further cleaning is achieved by blowing with gas.

[0026] The thus-cleaned ceramic plate, MMC plate, and bonding layer are then used to prepare a bonded structure by thermocompression bonding. For example, the bonding layer is sandwiched between the ceramic plate and the MMC plate, and the ceramic plate and the MMC plate are bonded via the bonding layer by thermocompression bonding at a pressure of 4 MPa to 30 MPa while being heated to a temperature below the liquidus temperature of the bonding material film. The thermocompression bonding 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 10 wt% Si and 1 wt% Mg is approximately 590°C, and the solidus temperature is approximately 560°C. Therefore, the thermocompression bonding temperature in this case is preferably in the range of approximately 520°C to less than approximately 540°C. In this way, a bonded structure of the present invention can be obtained in which the ceramic plate and the MMC plate are bonded via the bonding layer.

[0027] The present invention will be explained in more detail by the following examples, but the present invention is not limited to the following examples.

[0028] Examples 1 to 9 (1) Preparation of Ceramic Plates A disc-shaped aluminum oxide sintered body (thickness: 5 mm, diameter: 300 mm) with an embedded ESC electrode was prepared as a ceramic plate as follows. First, disc-shaped first and second alumina green sheets were prepared. An ESC electrode was formed on one surface of the first green sheet by screen printing, while a heater electrode was 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 on the surface of the first green sheet on which the ESC electrode was formed, and the second green sheet was laminated on top of that so that the heater electrode was in contact with the third green sheet. The resulting laminate was fired by a hot press method to obtain a ceramic sintered body with an embedded ESC electrode and heater electrode. Both surfaces of the obtained ceramic sintered body were subjected to grinding, blasting, etc. to adjust the shape and thickness, and a flat electrostatic chuck was obtained as a ceramic plate. The specific manufacturing conditions for this electrostatic chuck were set with reference to the conditions described in Japanese Patent Application Laid-Open No. 2006-196864.

[0029] (2) Preparation of MMC Plates A plate containing Si, C, and Ti (SiSiCTi plate) was prepared as an MMC plate as follows. First, as raw materials, SiC raw material (commercially available product with a purity of 97% or more and an average particle size of 15.5 μm), metal Si raw material (commercially available product with a purity of 97% or more and an average particle size of 9.0 μm), and metal Ti raw material (commercially available product with a purity of 99.5% or more and an average particle size of 31.1 μm) were prepared. The SiC raw material, metal Si raw material, and metal Ti raw material were weighed to a blend ratio of 49.5 mass% SiC, 20.0 mass% Si, and 30.5 mass% Ti, and then placed in a nylon pot together with isopropyl alcohol as a solvent. The mixture was wet-mixed for 4 hours using a 10 mm diameter nylon ball with an iron core. 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 / cm. ２ The molded product was then uniaxially pressed at a pressure of 200 kgf / cm under vacuum to produce a disk-shaped molded product with a diameter of 50 mm and a thickness of 17 mm, which was then placed in a graphite mold for sintering. The disk-shaped molded product was then hot-pressed and sintered to obtain an MMC plate. This hot-press sintering was carried out in a vacuum atmosphere at a pressure of 200 kgf / cm. ２ The firing was carried out by holding the material at a firing temperature (maximum temperature) of 1400° C. for 4 hours while applying a pressing pressure of 1.0 MPa.

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

[0031] (3) Preparation of Bonding Layer A 0.12 mm thick Al alloy sheet containing Si and Mg (alloy composition: Si: 10 wt %, Mg: 1 wt %, balance: Al and inevitable impurities) was prepared as a bonding layer.

[0032] (4) Cleaning Step The following cleaning steps (i) to (vi) were sequentially performed on each of the ceramic plate and the MMC plate, while only the following cleaning steps (i), (ii) and (iv) were sequentially performed on the Si- and Mg-containing Al alloy sheet. <Cleaning Step> (i) Ultrasonic cleaning using acetone (not performed in Example 9) (ii) Ultrasonic cleaning using isopropyl alcohol (IPA) (not performed in Example 9) (iii) Cleaning with running pure water (iv) N ２ Blow with gas (v) Dry at 120°C for 10 minutes

[0033] At this time, the total cleaning time of (i) ultrasonic cleaning using acetone and (ii) ultrasonic cleaning using isopropyl alcohol (IPA), i.e., the ultrasonic cleaning time with an organic solvent, was changed for each experimental example as shown in Table 1. Therefore, as described above, the ultrasonic cleanings (i) and (ii) above were not performed for Example 9.

[0034] (5) Thermocompression welding Thermocompression welding was performed using the cleaned ceramic plate, MMC plate, and bonding sheet as follows. That is, a bonding sheet was sandwiched between the ceramic plate and the MMC plate as a bonding layer, and the ceramic plate, MMC plate, and bonding sheet (bonding layer) were bonded to each other by thermocompression welding at a pressure of 20 MPa in a vacuum while heating to 530°C (a temperature lower than the liquidus temperature of the Si- and Mg-containing Al alloy and equal to or higher than a temperature approximately 30°C lower than the solidus temperature). In this way, a bonded body was obtained in which the ceramic plate and MMC plate were bonded via the bonding layer.

[0035] (6) Evaluation of the Bonded Structure The bonded structures thus produced were evaluated as follows.

[0036] <Obtaining Elemental Mapping Images by EPMA> A cross section of the resulting bonded body was cut out and mirror-polished, followed by flat ion milling with Ar ions to obtain an observation cross section. A 75 μm × 75 μm region of the obtained observation cross section, including the ceramic plate 12, the bonding interface 20, and the bonding layer 16, was observed with a SEM (scanning electron microscope). Elemental analysis of the region was performed with an EPMA (manufactured by JEOL Ltd.) at an acceleration voltage of 15 kV to obtain elemental mapping images of Si, C, Ti, O, Mg, and Al. Figures 3A and 3B show SEM images (Compo images) of a cross section of the bonded body of Example 7, including the ceramic plate 12, the bonding interface 20, and the bonding layer 16, and various elemental mapping images of the corresponding regions. As a result, as shown in Table 1 and Figures 3A and 3B, in the joined bodies of Examples 1 to 7, an Mg-containing layer 24 containing Mg at a higher concentration than the surrounding area was observed at the bonded 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 an Mg-containing layer was not observed.

[0037] In addition, 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 on the obtained observed cross section was also subjected to SEM observation and EPMA elemental analysis 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 element mapping images of the corresponding region. As a result, in all of the bonded bodies of Examples 1 to 9, as shown in Figures 4A and 4B, TiC particles (see black particles in the figure), TiSi ２ A microstructure containing a matrix (see the gray area in the figure) and SiC particles (see the white particles in the figure) was observed. In addition, it was confirmed that Mg and Al were diffused into the SiSiCTi constituting the MMC plate 14 in the joined bodies of Examples 1 to 7.

[0038] Furthermore, SEM observation and EPMA elemental analysis were performed in the same manner as above on a larger cross-sectional area of ​​300 μm × 300 μm, including the bonding layer 16, the bonding interface 22, and the bonding interface 22 between the MMC plate 14, except that the magnification was lowered and the concentration scale was reduced. Figures 5A and 5B 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 elemental mapping images of the corresponding region, with the concentration scale reduced. As a result, in the bonded bodies of Examples 1 to 9, the presence of an Al-enriched layer 26 and an Mg-diffused layer 28, which are considered to be formed by diffusion of Al and Mg, respectively, originating from the bonding layer 16, was confirmed in the MMC plate 14 from the bonding interface 22 in the depth direction of the MMC plate 14. The depth D of the Al-enriched layer 26 from the bonding interface 22 was 100 μm. Ａｌ and the depth D of the Mg diffusion layer 28 from the bonding interface 22 Ｍｇ When the values ​​were measured, the values ​​shown in Table 1 were obtained.

[0039] <Weight Ratio of Al:Mg:O in Mg-Containing Layer> From the EPMA measurement results, semi-quantitative values ​​of each element were calculated for each pixel equivalent to 0.24 μm × 0.24 μm, and the weight ratio of Al:Mg:O was calculated 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] <Bonding Strength> A long sample was cut from the resulting bonded body so that the bonding layer was located at the center of the longitudinal direction, and the surface of the sample 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 bonding interface at the center under 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 obtained maximum bending stress (MPa) was taken as the bonding strength. The results are shown in Table 1.

[0041]

[0042] Examples 10 to 12: Bonded bodies were produced and evaluated in the same manner as in Example 1, except that i) a plate containing Si, C, Ti, and Al (SiSiCTi+Al plate) produced as follows was used as the MMC plate, and ii) the ultrasonic cleaning time with an organic solvent was set as shown in Table 2. The results are shown in Table 2.

[0043] (Preparation of MMC Plate) An MMC plate containing Si, C, Ti, and Al (wherein Al may be in the form of AlN) was prepared as follows. First, as raw materials, a SiC raw material (commercially available product with a purity of 97% or more and an average particle size of 15.5 μm), a metal Si raw material (commercially available product with a purity of 97% or more and an average particle size of 9.0 μm), a metal Ti raw material (commercially available product with a purity of 99.5% or more and an average particle size of 31.1 μm), and an AlN raw material (commercially available product with a purity of 97% or more and an average particle size of 1.1 μm) were prepared. The SiC raw material, the metal Si raw material, the metal Ti raw material, and the AlN raw material were weighed out to a blend ratio of 49.5% by mass of SiC, 10.0% by mass of Si, 30.5% by mass of Ti, and 10.0% by mass of AlN, and then placed in a nylon pot together with isopropyl alcohol as a solvent. The mixture was wet-mixed for 4 hours using a 10 mm diameter nylon ball with an iron core. The obtained slurry was taken out, dried at 110°C in a nitrogen stream, and then passed through a 30-mesh sieve to obtain a blended powder. ２ The molded product was then uniaxially pressed at a pressure of 200 kgf / cm under vacuum to produce a disk-shaped molded product with a diameter of 50 mm and a thickness of 17 mm, which was then placed in a graphite mold for sintering. The disk-shaped molded product was then hot-pressed and sintered to obtain an MMC plate. This hot-press sintering was carried out in a vacuum atmosphere at a pressure of 200 kgf / cm. ２ The firing was carried out by holding the material at a firing temperature (maximum temperature) of 1400° C. for 4 hours while applying a pressing pressure of 1.0 MPa.

[0044] Examples 13 to 18: Bonded bodies were produced and evaluated in the same manner as in Example 1, except that i) an Mg-free Al—Si bonding layer prepared as follows was used, ii) thermocompression bonding was performed as follows, and iii) the ultrasonic cleaning time with an organic solvent was set as shown in Table 2. The results were as shown in Table 2.

[0045] (Preparation of Bonding Layer) A 0.12 mm thick Si and Al alloy sheet (alloy composition: Si: 10 wt %, balance: Al and inevitable impurities) was prepared as a bonding layer.

[0046] (Thermal Compression Welding) The ceramic plate, MMC plate, and bonding sheet were each cleaned and subjected to thermal compression welding as follows. A bonding sheet was sandwiched between the ceramic plate and the MMC plate as a bonding layer, and the ceramic plate, MMC plate, and bonding sheet (bonding layer) were bonded to each other by thermal compression welding at a pressure of 20 MPa in a vacuum while heating to 560°C (a temperature lower than the liquidus temperature of the Si and Al alloys and equal to or higher than a temperature approximately 30°C lower than the solidus temperature). This resulted in a bonded assembly in which the ceramic plate and MMC plate were bonded via the bonding layer.

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

[0048] Examples 22 to 24: Bonded bodies were produced and evaluated in the same manner as in Example 13, except that i) a plate containing Si, C, and Al (AlSiC plate) produced as follows was used as the MMC plate, and ii) the ultrasonic cleaning time with an organic solvent was set as shown in Table 2. The results are shown in Table 2.

[0049] (Preparation of MMC Plate) A plate containing Si, C, and Al was prepared as an MMC plate as follows. First, 5 parts by mass of PVB (polyvinyl butyral) as a binder and 5 parts by mass of colloidal silica were added to 100 parts by mass of SiC raw material as raw material powder, and the resulting mixture was press-molded to prepare a porous ceramic molded body (preform). The obtained preform was preheated to 700°C and placed inside a mold of a pressure device. Next, an aluminum alloy (AC3A) molten at 750°C was poured into the mold, and a pressure of 30 MPa was applied to infiltrate the molten aluminum alloy into the preform. The infiltration treatment was carried out for 10 minutes. Thereafter, the composite material in which the aluminum alloy had infiltrated the SiC was removed from the mold, and excess Al alloy adhering to the periphery of the composite material was ground off, yielding an MMC plate made of an Al-SiC composite material containing 70% by volume of SiC.

[0050] Examples 25 to 27 Bonded bodies were produced and evaluated in the same manner as in Example 19, except that i) an aluminum nitride sintered body produced as follows was used as the ceramic plate, and ii) the ultrasonic cleaning time with an organic solvent was set as shown in Table 2. The results are shown in Table 2.

[0051] (Fabrication of Ceramic Plate) A disc-shaped aluminum nitride sintered body (thickness: 5 mm, diameter: 300 mm) with an embedded ESC electrode was fabricated as a ceramic plate as follows. First, disc-shaped first and second aluminum nitride green sheets were prepared. An ESC electrode was formed on one surface of the first green sheet by screen printing, while a heater electrode was 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 on the surface of the first green sheet on which the ESC electrode was formed, and then the second green sheet was laminated on top of that so that the heater electrode was in contact with the third green sheet. The resulting laminate was fired by hot pressing to obtain a ceramic sintered body with an embedded ESC electrode and heater electrode. Both surfaces of the resulting ceramic sintered body were subjected to grinding, blasting, etc. to adjust the shape and thickness, and a flat electrostatic chuck was obtained as a ceramic plate.

[0052]

[0053] REFERENCE SIGNS LIST 10 Joined body 12 Ceramic plate 14 MMC plate 16 Joining layer 18 Internal electrode 20, 22 Joining interface 24 Mg-containing layer 26 Al-enriched layer 28 Mg-diffused layer

Claims

1. A ceramic plate; an MMC plate that is provided opposite one side of the ceramic plate and is made of a metal matrix composite (MMC) containing (i) Si, C, and Ti, or (ii) Al, Si, and C; and a bonding layer that is provided between the ceramic plate and the MMC plate and bonds the ceramic plate and the MMC plate, the bonding layer containing Al as a main component, wherein the MMC plate is located at a predetermined depth D from a 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 MMC plate, and the Al-enriched layer has a depth D Ａｌ The bonded body, wherein the thickness is 40 μm or more.

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

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

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

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

6. The MMC plate is bonded to a predetermined depth D from the bonding interface between the bonding layer and the MMC plate. Ｍｇ The joined body according to claim 5 , further comprising an Mg diffusion layer in which Mg derived from the joining layer is diffused throughout the joined body.

7. Depth D of the Al-enriched layer Ａｌ is the depth D of the Mg diffusion layer Ｍｇ That is, D Ａｌ >D Ｍｇ The joint body according to claim 6 , which satisfies the above.

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

9. The joint according to any one of claims 1 to 7, wherein the ceramic plate, the joint layer and the MMC plate are joined by thermocompression bonding.

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

11. The 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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