JP7628754B2 - Electrode-embedding member, its manufacturing method, and substrate holding member - Google Patents

Description

The present invention relates to an electrode-embedded member, a manufacturing method thereof, and a substrate-holding member.

Conventionally, electrode-embedded components such as susceptors, electrostatic chucks, and ceramic heaters, in which electrodes are embedded in a ceramic sintered body, have been proposed as components for semiconductor manufacturing equipment.

Patent Document 1 discloses a technology for providing a ceramic heater that has small variation in the resistance value of the heater electrode layer within the substrate and can uniformly heat semiconductor wafers, in which a heater electrode layer 5 is formed on an aluminum nitride green sheet using a conductive paste containing tungsten carbide particles, and then a heat treatment process is performed on the green sheet, in which the green sheet is heated in an inert gas atmosphere at a temperature range lower than the temperature at which tungsten carbide is formed, and then a firing process is performed to completely sinter the green sheet, completing the ceramic heater.

In Patent Document 1, a heater electrode layer is formed on a green sheet using a conductive paste containing tungsten carbide (WC) particles, which have the lowest resistivity among tungsten carbides. If such a conductive paste is used for the heat treatment process, uneven carbonization reactions in the green sheet are less likely to occur compared to conventional conductive pastes that do not contain any carbon in the particles, and the green sheet is then heated in a non-oxidizing atmosphere at a temperature range lower than that during main firing, and the organic matter contained in the sheet is decomposed and removed, resulting in a green sheet in a state suitable for main firing, and it is described that by main firing, a sintered aluminum nitride body with small variation in the resistance value of the heater electrode layer within the substrate can be obtained.

JP 2000-12194 A

When a ceramic sintered body is produced by simultaneously embedding an Mo electrode and a W connection member in a ceramic molded body and firing the body, the C component mixed in from the raw materials, jig, and environment inevitably reacts with the Mo electrode and the W connection member. In this case, for example, if the carbonization of Mo is actively promoted to increase the resistance value of the electrode, the W connection member also carbonizes at the same time, and the connection member itself becomes highly resistive and its function of electrically connecting the electrode and the (external) terminal deteriorates. Furthermore, the carbonization makes the connection member itself embrittled, and when the terminal is subsequently brazed to the connection member, cracks are likely to occur and the terminal strength decreases. Therefore, there has been a demand for an electrode embedding member and a manufacturing method thereof that simultaneously controls the carbonization of the Mo electrode and the W connection member when the Mo electrode and the W connection member are simultaneously embedded in a ceramic molded body and fired, thereby suppressing the above-mentioned deterioration in function.

However, although Patent Document 1 controls the carbonization of the electrode layer, it does not aim to actively carbonize the electrode layer, and is unable to control the carbonization of both the electrode layer and the connecting member.

The inventors noticed that the temperature at which carbonization begins is different between Mo and W, and discovered that by performing heat treatment at a temperature above the temperature at which Mo carbonizes and below the temperature at which W carbonizes, it is possible to promote carbonization of the Mo electrode while suppressing carbonization of the W connection member, thus completing the present invention.

In other words, the present invention has been made in consideration of these circumstances, and aims to provide an electrode embedding member, a manufacturing method thereof, and a substrate holding member that can increase the resistance of the electrode, increase the degree of freedom in electrode design, and keep the resistance of the connection member low, thereby improving the reliability of the electrical connection via the connection member.

(1) In order to achieve the above object, the present invention provides an electrode-embedded member comprising a flat base made of a sintered ceramic body, an electrode embedded in the base, and a connection member electrically connected to the electrode and embedded in the base, wherein the electrode is made of Mo carbide, the connection member contains W metal, and the connection member has a W carbide layer having a thickness of more than 0 μm and not more than 20 μm on its surface .

In this way, by constructing the electrodes from Mo carbide, the resistance of the electrodes can be increased, allowing for greater freedom in electrode design, while by making the connecting member contain W metal, the resistance of the connecting member can be kept low, improving the reliability of the electrical connection via the connecting member.

(2) As described above, in the electrode-embedded member of the present invention, the connection member has a W carbide layer having a thickness of more than 0 μm and not more than 20 μm on the surface.

In this way, by making the carbide layer on the surface of the connection member very thin, it is possible to prevent the connection member from becoming highly resistive, further improving the reliability of the electrical connection via the connection member, and also to prevent the connection member from becoming brittle, thereby reducing the risk of cracks occurring in the connection member.

(3) The electrode-embedded member of the present invention is further characterized by having a first member that is in contact with the connection member and is made of either Mo, Mo carbide, or a combination of Mo and Mo carbide.

This makes it possible to further suppress carbonization of the connection member, further improving the reliability of the electrical connection via the connection member, and further reducing the risk of cracks occurring in the connection member.

(4) In addition, in the electrode-embedded member of the present invention, the first member is a coating layer.

This makes it possible to further suppress carbonization of the connection member, further improving the reliability of the electrical connection via the connection member, and further reducing the risk of cracks occurring in the connection member.

(5) The substrate holding member of the present invention is characterized by comprising an electrode-embedded member according to any one of (1) to (4) above and a terminal electrically connected to the connection member.

This allows for the construction of a substrate holding member using an electrode-embedded member that provides a high degree of freedom in electrode design and improves the reliability of the electrical connection via the connection member, reducing the risk of connection problems occurring between the terminal and the connection member.

(6) The method for manufacturing an electrode-embedded member of the present invention is a method for manufacturing an electrode-embedded member formed of a ceramic sintered body, and is characterized by comprising a molded body forming process for forming a plurality of ceramic molded bodies from ceramic raw material powder, a degreasing process for degreasing the plurality of ceramic molded bodies at a predetermined temperature or higher for a predetermined time or longer to produce a plurality of ceramic degreased bodies, a preparation process for preparing an electrode formed of a mesh woven with Mo wires and a connection member formed of W, a precursor formation process for combining the electrode, the connection member, and the plurality of ceramic degreased bodies to form an electrode-embedded member precursor formed in a flat plate shape and having the electrode and the connection member embedded therein, a heat treatment process for heat-treating the electrode-embedded member precursor at 800°C to 1500°C for 14 hours or longer, and a firing process for firing the electrode-embedded member precursor after the heat treatment by uniaxial pressure firing in a direction perpendicular to the main surface of the electrode-embedded member precursor.

This promotes carbonization of the electrodes during the heat treatment process, allowing the entire electrode to be made of Mo carbide, while preventing the connection members from being carbonized at all. As a result, the resistance of the electrodes can be increased, allowing greater freedom in electrode design, while keeping the resistance of the connection members low and improving the reliability of the electrical connection via the connection members.

(7) The manufacturing method of the electrode-embedded member of the present invention is also characterized in that in the preparation step, a first member made of Mo is further prepared, and in the precursor formation step, the first member is placed in contact with the connection member, and the first member is embedded in the electrode-embedded member.

This makes it possible to further suppress carbonization of the connection member, suppress an increase in the resistance of the connection member, further improve the reliability of the electrical connection via the connection member, and suppress embrittlement of the connection member, thereby reducing the risk of cracks occurring in the connection member.

(8) In addition, in the manufacturing method of the electrode-embedded member of the present invention, the connection member prepared in the preparation step is characterized in that it is coated with Mo.

This makes it possible to further suppress carbonization of the connection member, suppress an increase in the resistance of the connection member, further improve the reliability of the electrical connection via the connection member, and suppress embrittlement of the connection member, thereby reducing the risk of cracks occurring in the connection member.

According to the present invention, by constructing the electrodes of the electrode-embedded member from Mo carbide, it is possible to increase the resistance of the electrodes and increase the degree of freedom in electrode design, and by making the connection member contain W metal, it is possible to keep the resistance of the connection member low and improve the reliability of the electrical connection via the connection member.

2 is a cross-sectional view showing an example of an electrode-embedded member according to the first embodiment. FIG. 2 is a cross-sectional view showing an example of a substrate holding member according to the first embodiment. FIG. 4 is a flowchart showing a method for manufacturing an electrode-embedded member according to the first embodiment. 3A to 3D are cross-sectional views each showing a schematic diagram of a step in the manufacturing process of the electrode-embedded member according to the first embodiment. 5A to 5C are cross-sectional views each showing a schematic diagram of a stage in the manufacturing process of the substrate holding member according to the first embodiment. FIG. 11 is a cross-sectional view showing an example of an electrode-embedded member according to a second embodiment. FIG. 11 is a partial cross-sectional view showing a modified example of an electrode-embedded member according to the second embodiment. 10 is a cross-sectional view showing an example of a substrate holding member according to a second embodiment. FIG. 1 is a table showing the production conditions and measurement results of Examples and Comparative Examples.

Next, an embodiment of the present invention will be described with reference to the drawings. To facilitate understanding of the description, the same reference numbers are used for the same components in each drawing, and duplicate descriptions will be omitted. Note that in the configuration diagrams, the size of each component is shown conceptually and does not necessarily represent the actual dimensional ratio.

[First embodiment]
[Configuration of electrode-embedded member]
First, the configuration of the electrode-embedded member according to the present embodiment will be described. Fig. 1 is a cross-sectional view showing an example of the electrode-embedded member according to the present embodiment. The electrode-embedded member 100 according to the present embodiment includes a base 110, an electrode 120, and a connection member 130. The electrode-embedded member 100 is applied to a heater, an electrostatic chuck, and the like.

The base 110 is made of a ceramic sintered body, formed in a flat plate shape, and has a mounting surface 112 on one of _its main surfaces for mounting a substrate. Various materials can be used for the material _of the base 110 depending on the application. For example, AlN, _Al2O3 , _Si3N4 , SiC, etc. can be used. The shape of the base 110 can be various shapes, such as a disk shape, a polygonal shape, an elliptical shape, etc.

The ceramic sintered body forming the base 110 is preferably composed mainly of AlN. The term "composed mainly of AlN" means that the ceramic sintered body contains 90 wt% or more of AlN. In order to increase the thermal conductivity of AlN ceramics, sintering aids made of oxides of 2a group elements or 3a group elements are often added. In general, it is known that the thermal conductivity increases when the amount of sintering aid added is increased, but adding more than a certain amount causes a decrease in thermal conductivity. Therefore, it is desirable to set the content of the sintering aid made of oxides of 2a group elements or 3a group elements to 10 wt% or less. Examples of additives of 2a group elements include Mg, Ca, Sr, Ba, etc., and examples of additives of 3a group elements include Y, La, Sm, Ce, etc.

Ceramic sintered bodies mainly composed of AlN have high thermal conductivity and excellent heat resistance and plasma resistance, and the thermal conductivity can be easily adjusted by adjusting the type and amount of sintering aid added. Therefore, by forming the base 110 from a ceramic sintered body mainly composed of AlN, it is possible to form a base 110 with an adjustable thermal conductivity, excellent heat resistance and plasma resistance.

The electrode 120 is embedded in the substrate 110 and is made of Mo carbide. By making the electrode 120 out of Mo carbide in this way, the resistance of the electrode 120 can be increased, and the degree of freedom in electrode design can be increased. The electrode 120 being made of Mo carbide means that an element mapping analysis of the entire cross section of the electrode 120 is performed in an EPMA analysis, C and Mo are quantified in atom % terms using the ZAF method, and the C/(C+Mo) ratio is found to be 0.20 or more.

The electrode 120 is preferably formed of a mesh in which wires are woven. The wires forming the mesh preferably have a wire diameter of 0.02 mm or more and 0.15 mm or less. Mo and Mo carbide have a high melting point and are difficult to process, so wires with a wire diameter of less than 0.02 mm are difficult to manufacture. If wires with a wire diameter of more than 0.15 mm are woven to form a mesh, there is a high risk of the wires cracking during sintering. In addition, the thickness of the mesh at the intersections of the wires is greater than 0.25 mm, and when the ceramics on the upper part of the electrode 120 are configured as a thin insulating layer, there is an increased risk of cracking the insulating layer. In this way, by forming the electrode 120 with sufficiently thin wires, the risk of the wires cracking during sintering can be further reduced, and even if the ceramics on the upper part of the electrode 120 are configured as a thin insulating layer, the risk of cracking the insulating layer can be further reduced.

The substrate 110 may have multiple electrodes. For example, by providing a heater electrode and an electrostatic attraction electrode, the electrode-embedded member 100 can be used as a heater-equipped electrostatic chuck. In that case, at least one of the electrodes may be the electrode 120 of the present invention. Two or more electrodes may be the electrode 120 of the present invention.

The connection member 130 is embedded in the base 110 and electrically connected to the electrode 120. This allows electricity to be supplied to the electrode 120 via the connection member 130. The connection member 130 contains W metal. The connection member 130 contains W metal when this is confirmed by detecting 0.9 or more W in a cross section of the connection member 130 in a quantitative analysis using the ZAF method of EPMA.

The thickness of the connection member 130 is preferably 0.2 mm or more and 5 mm or less. If it is less than 0.2 mm, there is an increased risk of breakage when forming the terminal hole 142 for connecting the terminal 140. If it is more than 5 mm, there is an increased risk of cracks occurring in the base 110 due to the difference in contraction rate between the base 110 and the ceramics during firing and the difference in thermal expansion rate during use.

It is preferable that the connection member 130 has a W carbide layer on the surface that is greater than 0 μm and not greater than 20 μm. In this way, by making the carbide layer on the surface of the connection member 130 very thin, it is possible to prevent the connection member 130 from becoming highly resistive, further improving the reliability of the electrical connection via the connection member 130, and also to prevent the connection member 130 from becoming brittle, thereby reducing the risk of cracks occurring in the connection member 130. Since the manufacturing method of the present invention makes it difficult for W to be carbonized, it is possible to make the W carbide layer on the surface of the connection member 130 thin.

The electrode-embedded member of the present invention is made of Mo carbide, which increases the resistance of the electrode and allows for greater freedom in electrode design. In addition, the connection member contains W metal, which keeps the resistance of the connection member low and improves the reliability of the electrical connection via the connection member.

[Configuration of the substrate holding member]
2 is a cross-sectional view showing an example of the substrate holding member according to the first embodiment. The substrate holding member 200 according to this embodiment is provided with a terminal hole 142 in the electrode embedding member 100 according to this embodiment, and is provided with a terminal 140. The terminal 140 is electrically connected to the connection member 130. This allows power to be supplied to the electrode 120. The terminal 140 can be made of Ni or the like. The terminal 140 is brazed to the connection member 130 with Au solder or the like. An intermediate member 150 made of Kovar or the like may be provided between the connection member 130 and the terminal 140.

The substrate holding member of the present invention allows for a high degree of freedom in electrode design, and can be configured to use electrode-embedded members that improve the reliability of electrical connections via connection members, thereby reducing the risk of connection problems occurring between the terminals and connection members.

[Method of manufacturing electrode-embedded member]
Next, a manufacturing method of the electrode-embedded member according to the present embodiment will be described. FIG. 3 is a flow chart showing a manufacturing method of the electrode-embedded member according to the first embodiment of the present invention. As shown in FIG. 3, the manufacturing method of the electrode-embedded member according to the first embodiment of the present invention includes a molded body forming step STEP 1, a degreasing step STEP 2, a preparation step STEP 3, a precursor forming step STEP 4, a heat treatment step STEP 5, and a firing step STEP 6. Note that, in the following, a manufacturing method using a molded body hot pressing method in which molded bodies are stacked and manufactured will be described, but in the present invention, the temperature and time of the heat treatment step STEP 5 are important, and the other steps may be replaced with other methods.

Figures 4(a) to (d) are cross-sectional views each showing a schematic diagram of one stage in the manufacturing process of the electrode-embedded member according to this embodiment. Figures 4(a) to (d) show the case of manufacturing the electrode-embedded member of Figure 1.

In the molded body forming step STEP 1, multiple ceramic molded bodies 11 and 12 are formed from ceramic raw material powder. In FIG. 4, the ceramic molded body is divided into two members, but it may be three or more depending on the design. For example, additives such as binder, plasticizer, and dispersant are appropriately added to the ceramic raw material powder and mixed to prepare a slurry, and granules (ceramic raw material powder) are granulated by a spray drying method or the like, and then pressure-molded to form multiple ceramic molded bodies 11 and 12. When using a manufacturing method using a binder like this, the C component derived from the binder will remain in the ceramic degreased body at about 100 ppm to 500 ppm even after the degreasing step described below. It is presumed that this C component causes carbonization. In the present invention, since it is necessary to sufficiently carbonize the Mo of the electrode, it is preferable that this amount of C component remains in the degreased body. Powder that serves as a sintering aid may be added to the ceramic raw material powder as necessary.

The ceramic raw material powder is preferably of high purity, preferably 96% or more, more preferably 98% or more. The average particle size of the ceramic raw material powder is preferably 0.1 μm or more and 1.0 μm or less.

The mixing method may be either wet or dry, and a mixer such as a ball mill or a vibration mill may be used. The forming method may be a known method such as uniaxial pressing or cold isostatic pressing (CIP). The method of forming the ceramic molded body is not limited to pressing, and may be, for example, green sheet lamination or casting, which may be appropriately degreased or further calcined to produce the ceramic molded body. A powder hot pressing method may also be used to form the electrode embedding member precursor.

After forming the multiple ceramic molded bodies 11, 12, the shape of the molded bodies may be adjusted by machining. Also, as shown in FIG. 4(b), a recess may be formed on one side of the ceramic molded body 12 (the joining surface with the other ceramic molded body 11) in a shape that matches the shape of the electrode 120 and the connecting member 130. The recess may be provided on the ceramic molded body 11, or on both sides. The machining may be performed after degreasing.

In the degreasing step STEP 2, the ceramic molded bodies 11, 12 are degreased at a predetermined temperature or higher for a predetermined time or longer to produce a plurality of ceramic degreased bodies 21, 22. The ceramic molded bodies 11, 12 are heat treated at a temperature of, for example, 400°C or higher and 800°C or lower to become the ceramic degreased bodies 21, 22. The degreasing time is preferably 1 hour or higher and 120 hours or lower. For degreasing, an atmospheric furnace or a nitrogen atmosphere furnace can be used, but an atmospheric furnace is preferable to remove unnecessary components of the binder.

In the preparation step STEP 3, an electrode 120 formed from a mesh woven with Mo wire and a connection member 130 formed from W are prepared.

The material of the electrode 120 is mainly composed of Mo. The term "mainly composed of Mo" means that the purity is 98 wt% or more, and the total of other transition metals, rare earth elements, or their compounds, and C is 2 wt% or less. The electrode 120 mainly composed of Mo undergoes a heat treatment process STEP 5 and a firing process STEP 6 described below, and becomes an electrode 120 composed of Mo carbide. The electrode 120 is prepared by processing into a shape according to the design of the electrode embedding member 100. The shape is preferably a mesh with wires woven in consideration of ease of carbonization. When the electrode 120 is in the shape of a mesh, the wire diameter of the wire forming the mesh is preferably 0.02 mm or more and 0.15 mm or less.

The material of the connection member 130 is mainly composed of W. "Mainly composed of W" indicates that the purity is 97 wt% or more, and that the total of other transition metals and rare earth elements or their compounds and C is 3 wt% or less. The connection member 130 mainly composed of W is less likely to carbonize even after undergoing the heat treatment process STEP 5 and the firing process STEP 6 described below, and therefore becomes a connection member 130 containing W metal. In addition, the connection member 130 is prepared by processing it into a shape according to the design of the electrode embedding member 100, and is embedded in a position according to the design.

In the precursor formation process STEP 4, the prepared electrode 120, connection member 130, and multiple ceramic degreased bodies 21, 22 are combined to form an electrode-embedded member precursor 30 formed in a flat plate shape with the electrode 120 and connection member 130 embedded therein.

In the heat treatment step STEP 5, the formed electrode embedding member precursor 30 is heat treated at 800°C to 1500°C for 14 hours or more. As a result, the Mo in the electrode 120 is carbonized to become Mo carbide. On the other hand, since the heat treatment is performed at a temperature lower than the carbonization temperature of W, the W in the connection member 130 is less likely to be carbonized.

In the firing step STEP6, the heat-treated electrode-embedded member precursor 30 is uniaxially pressurized and fired in a direction perpendicular to the main surface (mounting surface) to obtain the electrode-embedded member 100. The pressure is preferably 1 MPa or more. The firing temperature is preferably greater than 1500°C and less than 2000°C. The firing time is preferably 1 hour or more and less than 12 hours. The firing atmosphere is, for example, a nitrogen or inert gas atmosphere, but may also be a vacuum atmosphere. As a result, the multiple ceramic degreased bodies 21 after the heat treatment are sintered to become ceramic sintered bodies, which are integrated to obtain the electrode-embedded member 100 in which the electrodes 120 and the connecting members 130 are embedded. The firing may be performed by increasing the temperature continuously from the heat treatment.

In this way, it is possible to manufacture an electrode-embedded member that can increase the resistance of the electrode, allowing for greater freedom in electrode design, while keeping the resistance of the connection member low and improving the reliability of the electrical connection via the connection member.

A ceramic calcined body preparation step may be provided between the degreasing step STEP 2 and the precursor formation step STEP 4. When the ceramic calcined body preparation step is provided, the ceramic degreased body is calcined at a temperature of 1200°C to 1700°C to prepare a ceramic calcined body. This allows for higher dimensional accuracy of the outer shape of the electrode-embedded member and the embedded positions of the electrodes and connecting members. The calcination time is preferably 0.5 hours to 12 hours. The calcination atmosphere is preferably a nitrogen or inert gas atmosphere, but may be a vacuum atmosphere or the like. When the calcined body preparation step is provided, machining may be performed after the calcined body preparation step.

[Method of manufacturing the substrate holding member]
5(a) to 5(c) are cross-sectional views each showing a schematic diagram of a step in the manufacturing process of the substrate holding member according to the present embodiment, in which the substrate holding member shown in FIG.

A terminal hole 142 is provided in the electrode-embedded member 100 after firing to expose the surface of the connection member 130. At this time, if a W carbide layer (not shown) is formed on the surface of the connection member 130, the W carbide layer in the area of the terminal hole is also removed. This allows the terminal 140 to be connected to the W metal of the connection member 130, whose resistance is kept low. The terminal 140 is connected to the exposed connection member 130 with brazing material or the like. Ni or the like can be used for the terminal. Au brazing material or the like can also be used for the brazing material. An intermediate member 150 made of Kovar or the like can be placed between the connection member 130 and the terminal 140 and brazed.

In this way, it is possible to construct a substrate holding member using an electrode-embedded member that provides a high degree of freedom in electrode design and improves the reliability of the electrical connection via the connection member, and it is possible to manufacture a substrate holding member 200 that can reduce the risk of problems occurring in the connection between the terminal and the connection member.

Second Embodiment
[Configuration of electrode-embedded member]
Next, the configuration of an electrode-embedded member according to the second embodiment will be described. Fig. 6 is a cross-sectional view showing an example of an electrode-embedded member according to this embodiment. The electrode-embedded member 100 according to this embodiment includes a base 110, an electrode 120, a connection member 130, and a first member 160. The electrode-embedded member 100 is applied to heaters, electrostatic chucks, and the like. Except for the inclusion of the first member 160, the basic configuration of the electrode-embedded member 100 is the same as that of the first embodiment, and only the different parts will be described.

The first member 160 is in contact with the connection member 130 and is made of either Mo, Mo carbide, or a combination of Mo and Mo carbide. This makes it possible to further suppress carbonization of the connection member 130, further improving the reliability of the electrical connection via the connection member 130 and further reducing the risk of cracks occurring in the connection member 130.

When the first member 160 is provided as a plate-like member, it is preferable that the shape of the first member 160 is the same as that of the connection member 130, and the thickness is 0.2 mm to 5 mm. If it is less than 0.2 mm, the forming process and the arrangement process become difficult. If it is more than 5 mm, the risk of cracks occurring in the base 110 increases due to the difference in contraction rate between the base 110 and the ceramics during firing and the difference in thermal expansion rate during use. When the first member 160 is provided as a plate-like member, it is preferable that the first member 160 is arranged on the side of the connection member 130 that is connected to the terminal 140.

Figure 7 is a partial cross-sectional view showing a modified example of the electrode-embedded member according to this embodiment. In the example of Figure 6, the first member 160 is provided as a member separate from the connection member 130, but the first member 160 may be provided as a coating layer 162 that coats the connection member 130, as in the example of Figure 7.

The thickness of the coating layer 162 is preferably 0.1 μm or more and 100 μm or less. A layer thinner than 0.1 μm is difficult to manufacture and consumes less C component, so the carbonization suppression effect of the connection member 130 is reduced. If a layer thicker than 100 μm is to be provided, it is easier to use a separate member instead of the coating layer 162.

When the connection member 130 is formed as a plate-like member, the coating layer 162 is preferably provided on both main surfaces of the connection member 130 from the viewpoint of suppressing carbonization of the connection member 130, but may be provided on only one surface. When provided on only one surface, the coating layer 162 is preferably provided on the side of the connection member 130 that is connected to the terminal 140. Note that the connection member 130 provided with the coating layer 162 may be used in combination with the plate-like first member 160.

This allows the first member 160 to be provided in advance as a coating layer 162 on the connection member 130, facilitating manufacturing and consuming the C component closer to the connection member 130. As a result, carbonization of the connection member 130 can be further suppressed, the reliability of the electrical connection via the connection member 130 can be further improved, and the risk of cracks occurring in the connection member 130 can be further reduced.

[Configuration of the substrate holding member]
8 is a cross-sectional view showing an example of the substrate holding member according to the present embodiment. The substrate holding member 200 according to the present embodiment is provided with a terminal hole 142 in the electrode-embedded member 100 according to the present embodiment and is provided with a terminal 140. At this time, it is preferable to remove the first member 160 or the coating layer 162 in the range of the terminal hole 142. The first member 160 or the coating layer 162 other than the range of the terminal hole 142 may be left as it is. If a W carbide layer (not shown) is formed on the surface of the connection member 130 after removing the first member 160 or the coating layer 162, the W carbide layer in the range of the terminal hole is also removed. This allows the terminal 140 to be connected to the W metal of the connection member 130, whose resistance is kept low.

[Method of manufacturing electrode-embedded member and substrate-holding member]
The method of manufacturing the electrode-embedded member and the substrate-holding member according to this embodiment is almost the same as the method of manufacturing the electrode-embedded member and the substrate-holding member according to the first embodiment, so only the different parts will be explained.

In the manufacturing method of the electrode-embedded member and the substrate-holding member according to this embodiment, in addition to the electrode 120 and the connection member 130, a first member 160 made of Mo or a connection member 130 made of Mo-coated W is prepared in the preparation step.

Thereby, the C component near the connection member 130 is consumed by the first member 160 or the coating layer 162 during heat treatment and firing. As a result, carbonization of the connection member 130 can be further suppressed, the reliability of the electrical connection via the connection member 130 can be further improved, and the risk of cracks occurring in the connection member 130 can be further reduced. The coating layer 162 can be provided on the W connection member 130 by plating or spraying. When forming a recess in a ceramic molded body or a ceramic degreased body, it is preferable to form the recess while taking into consideration the thickness of the first member 160 or the coating layer 162.

[Examples and Comparative Examples]
Example 1
A ceramic raw material powder mainly composed of AlN _to which 5 wt% _Y2O3 was added was used to perform CIP molding (pressure 1 ton/ ^cm2 ) to obtain an ingot of a molded body. This was machined to mold a ceramic molded body with a diameter of 340 mm and a thickness of 5 mm, and a ceramic molded body with a diameter of 340 mm and a thickness of 30 mm. Then, on one side of the ceramic molded body with a thickness of 30 mm, a recess with a diameter of 300 mm and a depth of 0.1 mm was provided to share the center of the molded body and to accommodate an electrode. Furthermore, a recess with a diameter of 8.5 mm and a depth of 0.25 mm was provided to accommodate a connecting member at a predetermined position to form a terminal.

Next, the ceramic molded body was degreased at 550°C for 12 hours to prepare a ceramic degreased body. Next, a molybdenum mesh (wire diameter 0.1 mm, plain weave, mesh size #50) made of molybdenum with a diameter of 294 mm was cut into a specified shape to prepare an electrode. In addition, two connecting members with a size of φ8 mm x 0.2 mmt were made from W pellets. Next, the connecting members and electrodes were placed in the recesses of the ceramic degreased body with recesses, and sandwiched between the other ceramic degreased body to prepare an electrode-embedded member precursor.

Next, the electrode-embedded member precursor was placed in a hot press furnace and heat-treated from 800°C to 1500°C for 14 hours. Next, the electrode-embedded member precursor was uniaxially hot-pressed and sintered at 1800°C for 2 hours while applying a force of 10 MPa in a direction perpendicular to the main surface (mounting surface) of the electrode-embedded member precursor. In this manner, the electrode-embedded member was sintered.

Then, the entire surface was ground and polished to form a wafer mounting surface with a total thickness of 25 mm, an insulating layer thickness of 1.0 mm, and a surface roughness of Ra 0.4 μm. A flat-bottom hole with a hole diameter of φ5.5 mm was drilled from the back side of the ceramic base to the terminal position of the connection member. A Kovar buffer member with a diameter of 5 mm and a thickness of 2 mm and a cylindrical Ni power supply terminal with a diameter of 5 mm and a length of 30 mm were installed on the exposed bottom surface of the connection member via brazing material, and brazing was performed at 1050°C with Au-Ni-based brazing material in a vacuum furnace to complete the substrate holding member. In this way, the substrate holding member of Example 1 was produced.

Example 2
In Example 2, a connecting member in which Mo was plasma sprayed onto the surface of W to form a coating having a thickness of 20 μm was used instead of the W connecting member used in Example 1. A substrate holding member for Example 2 was produced under the same conditions as in Example 1 except for the above.

Example 3
In Example 3, a Mo member (first member) was embedded in the W connection member of Example 1. The Mo member had a diameter of 8 mm and a thickness of 0.8 mm. After firing, the Mo member in the area of the terminal hole was removed by processing. The substrate holding member of Example 3 was produced under the same conditions as Example 1.

Example 4
In Example 4, a substrate holding member of Example 4 was produced under the same conditions as in Example 1, except that the heat treatment time was 20 hours.

(Example 5)
In Example 5, a substrate holding member of Example 5 was produced under the same conditions as in Example 1, except that the heat treatment time was 12 hours.

(Comparative Example 1)
In Comparative Example 1, no long-term heat treatment was performed. That is, the temperature was raised from 800° C. to 1500° C. for 7 hours, the same as in the conventional method, and then uniaxial pressure firing was performed for 2 hours at 1800° C. The substrate holder of Comparative Example 1 was produced under the same conditions as in Example 1.

(Comparative Example 2)
In Comparative Example 2, a Mo-coated connecting member similar to that in Example 2 was used. A substrate holding member for Comparative Example 2 was produced under the same conditions as in Comparative Example 1 except for the above.

(Comparative Example 3)
In Comparative Example 3, a Mo member (first member) was embedded in a W connection member in the same manner as in Example 3. The substrate holding member of Comparative Example 3 was produced under the same conditions as in Comparative Example 1 except for the above.

[Performance evaluation]
(Measurement of temperature distribution)
After installing the fabricated substrate holding member (heater) in the evaluation chamber, the temperature was controlled at 400°C by self-heating, and the surface distribution was measured with an IR camera. The measurement area was within a Φ290 mm range, and the temperature variation was evaluated as ΔT = maximum value - minimum value.

(Evaluation of resistance variation)
After the temperature distribution measurement, terminal holes for resistance measurement were provided at predetermined positions to expose the heater electrodes. A tester probe was brought into contact with the heater electrodes exposed in the predetermined terminal holes, and the heater resistance between the predetermined terminals was measured at eight locations (four locations on the outer periphery at a radius of 135 mm, and four locations on the inner periphery at a radius of 50 mm). The ratio (Rm/Rd) of the design resistance value Rd to the measured resistance value Rm at the eight locations (maximum value - minimum value)/average value was evaluated as the resistance variation of the electrodes.

(Composition analysis of electrodes and connecting materials)
The heater was cut in a vertical cross section passing through the center of the mounting surface and the center of the connecting member, and the cross sections of the electrodes and connecting members were exposed and polished, after which elemental analysis was performed using EMPA and qualitative analysis was performed using XRD. Elemental analysis of the electrodes was performed on three positions: the position closest to the center of the mounting surface, the position closest to the outer periphery, and the position closest to the midpoint of the two.

EPMA analysis of the electrode involved performing elemental mapping analysis of the cross section of the electrode using a FE-EPMA (field emission electron microanalyzer), and carbides were determined using the ZAF method based on the C/(C+Mo) ratio converted into atom %. When the C/(C+Mo) ratio was 0.20 or greater, it was determined to be composed of Mo carbides, and when the C/(C+Mo) ratio was less than 0.20, it was determined that uncarbonized Mo remained. In addition, XRD involved performing X-ray diffraction of the cross section (a region with a diameter of approximately 3100 μm, including the diameter of the electrode) using μ-XRD (micro X-ray diffraction).

The EPMA analysis of the connection member was carried out by performing elemental mapping analysis of the cross section of the end of the connection member using a FE-EPMA (field emission electron microanalyzer). The formation of carbides was confirmed based on the presence or absence of areas where C was detected, and the thickness of the W carbide layer was measured based on the contrast difference between areas where carbides had formed and areas where they had not in the SEM images.

In Examples 1 to 5, the thickness of the carbonized layer on the surface of the W connection member could be reduced compared to Comparative Example 1. This is presumably because the time required for the process to reach 800 to 1500°C was sufficiently longer than that required for the conventional manufacturing method, and at least the C component near the connection member was consumed by the Mo electrode, Mo coating layer, and Mo first member, among the C components from the raw material, jig, and environment. At the same time, it was confirmed by both EPMA and XRD that the wire of the heater electrode was Mo carbide (Mo ₂ C) at all of the above three points. The value of the C/(C+Mo) ratio in FIG. 9 indicates the value at the point where the value was the smallest among the above three points. Therefore, it was found that a heat treatment time of 12 hours or more is sufficient to carbonize all the electrodes.

On the other hand, in Example 5, the thickness of the carbonized layer of the connection member was greater when compared with Examples 1 and 4, which were identical in conditions except for the heat treatment time. Since it is preferable for the carbonized layer of the connection member to be as thin as possible, it was found that the heat treatment time is preferably 14 hours or more, and more preferably 20 hours or more. The reason why the thickness of the carbonized layer becomes thinner as the heat treatment time is longer is presumably because the C component is not only consumed by Mo during the heat treatment, but is also emitted as gas such as CO.

In contrast, the carbonized layer on the surface of the W connecting member was thicker in Comparative Examples 1 to 3. At the same time, there were some parts of the wire cross section of the heater electrode that had a composite structure of Mo and Mo ₂ C. Comparative Examples 2 and 3, which used Mo-coated connecting members or Mo pellets (first members), had thinner carbonized layers on the connecting members than Comparative Example 1, but the electrodes could not be carbonized entirely, so the variation in electrode resistance was large, just like Comparative Example 1, and the temperature distribution on the heater surface was also large.

As a result, it was confirmed that, compared to the comparative example, in Examples 1 to 5, the mixture of Mo and Mo ₂ C was eliminated, the variation in heater resistance was improved, and the heater surface temperature distribution was improved. In addition, it was confirmed that the carbonization and embrittlement of the W connection member were suppressed, so that the reliability of brazing the terminal to the connection member could be improved. Furthermore, it was confirmed that the manufacturing method of the present invention can manufacture such electrode-embedded members and substrate holding members.

The present invention is not limited to the above-described embodiment, and it goes without saying that it covers various modifications and equivalents that fall within the spirit and scope of the present invention. Furthermore, the structure, shape, number, position, size, etc. of the components shown in each drawing are for convenience of explanation and may be changed as appropriate.

Reference Signs List 11, 12 Ceramic molded bodies 21, 22 Ceramic degreased body 30 Electrode-embedding member precursor 100 Electrode-embedding member 110 Base body 112 Mounting surface 120 Electrode 130 Connection member 140 Terminal 142 Terminal hole 150 Intermediate member 160 First member 162 Coating layer 200 Substrate holding member

Claims (7)

An electrode embedding member,
A flat plate-shaped base body made of a ceramic sintered body;
an electrode embedded in the substrate;
a connection member electrically connected to the electrode and embedded in the base,
The electrode is made of Mo carbide,
The connection member includes a W metal, and has a W carbide layer having a thickness of more than 0 μm and not more than 20 μm on a surface of the connection member . 2. The electrode-embedded member according to claim 1, further comprising a first member in contact with the connection member and made of any one of Mo, Mo carbide, or a combination of Mo and Mo carbide. 3. The electrode-embedded member according to claim 2 , wherein the first member is a coating layer. An electrode-embedded member according to any one of claims 1 to 3 ,
a terminal electrically connected to the connection member. A method for manufacturing an electrode-embedded member formed of a ceramic sintered body, comprising the steps of:
a compact forming step of forming a plurality of ceramic compacts from the ceramic raw material powder;
a degreasing step of degreasing the plurality of ceramic molded bodies at a predetermined temperature or higher for a predetermined time or longer to produce a plurality of ceramic degreased bodies;
A preparation step of preparing an electrode formed of a mesh woven with Mo wires and a connection member formed of W;
a precursor forming step of combining the electrodes, the connection members, and the plurality of ceramic degreased bodies to form a plate-shaped electrode-embedded member precursor in which the electrodes and the connection members are embedded;
a heat treatment step of heating the electrode-embedded member precursor from 800° C. to 1500° C. over 14 hours or more;
a firing step of uniaxially pressurizing and firing the heat-treated electrode-embedded member precursor in a direction perpendicular to a main surface of the electrode-embedded member precursor to obtain an electrode-embedded member. In the preparation step, a first member made of Mo is further prepared;
6. The method for producing an electrode-embedded member according to claim 5 , wherein in the precursor formation step, the first member is disposed in contact with the connection member, and the first member is embedded in the electrode-embedded member. 7. The method for manufacturing an electrode-embedded member according to claim 5 , wherein the connection member prepared in the preparation step is coated with Mo.

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