JP7628358B2 - 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 ceramic heater technology for preventing the resistance heating element from increasing in resistance and breaking when the ceramic heater is used for a long period of time by repeatedly subjecting it to heating-cooling cycles, the ceramic heater having a base material made of ceramics and a resistance heating element embedded in the base material, the resistance heating element having a main body made of a high melting point metal and a coating film coating the main body, the thermal expansion coefficient of the coating film being greater than the thermal expansion coefficient of the main body, and the coating film having a thickness of 2 μm or more. Patent Document 1 also describes that the coating film is preferably made of a material selected from the group consisting of TiN, _Mo2C , NbC, TiC, VC, ZrC, WC, TaC, TaN, and ZrN, the high melting point metal is tungsten, and particularly preferably the coating film is made of TiN.

Patent Document 2 discloses a silicon nitride member and a manufacturing method thereof that can improve resistance changes during repeated temperature rise and fall tests and can produce highly reliable ceramic heaters, and discloses a silicon nitride member in which a high-melting point metal such as tungsten or molybdenum is embedded in a material whose main component is silicon nitride, and the high-melting point metal is coated with a high-melting point metal carbide, and a manufacturing method for a silicon nitride member in which a carbon-containing high-melting point metal such as tungsten or molybdenum is embedded in a silicon nitride molded body and then fired, and at least a high-melting point metal carbide is generated on the surface of the high-melting point metal during firing.

Patent Document 3 discloses a technology for manufacturing a ceramic heater, with the aim of providing a ceramic heater that has small variation in the resistance value of the heater electrode layer within the substrate and can uniformly heat a semiconductor wafer, in which a heater electrode layer is formed on an aluminum nitride green sheet using a conductive paste containing tungsten monocarbide 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 formation temperature of tungsten monocarbide, and then a firing process is performed to completely sinter the green sheet, completing the ceramic heater 1.

Japanese Patent Application Publication No. 07-135068 Japanese Patent Application Publication No. 04-087181 JP 2000-12194 A

When embedding a mesh electrode in a ceramic sintered body, it may be difficult to set the resistance of the electrode high depending on the shape of the mesh. This is due to the fact that the volume resistivity of the metal itself is essentially low. However, there are cases where the resistance value of the electrode is required to be high due to the specifications of the power supply and other usage constraints. In such cases, it is necessary to narrow the cutting width of the mesh and lengthen it in the longitudinal direction, but there is a limit to narrowing the cutting width because the number of wires within the cutting width directly affects the variation in the resistance value and reduces the reliability of the electrode. For example, when using an electrode-embedded member as a heater, if the cutting width is made too narrow, the temperature distribution within the substrate surface will vary, so simply narrowing the cutting width will not produce a reliable electrode with sufficient resistance and uniform temperature distribution within the substrate surface.

In addition, when Mo is used as a mesh electrode, the Mo mesh electrode must be embedded in a ceramic molded body and fired, but it reacts with the binder of the ceramic raw material, the carbon jig, and the C component mixed in from the environment. Therefore, the reactivity varies depending on the manufacturing conditions and the position of the electrode, so the degree of carbonization of Mo varies, and the resistance value of the Mo electrode varies within the substrate surface, which results in a variation in the temperature distribution within the substrate surface. This is because Mo has a small volume resistivity, but the volume resistivity of carbonized Mo ₂ C is large, and this effect becomes significant. In addition, although it is possible to embed carbide Mo ₂ C in advance to increase the volume resistivity, Mo ₂ C is brittle and has low strength and ductility, so it is not practical to weave Mo ₂ C into a mesh.

Therefore, there was a need for an electrode embedding material that would promote carbonization of the Mo mesh electrode when it is embedded in a ceramic molded body and sintered, thereby increasing the resistance value of the heater electrode by carbonizing the entire electrode, while suppressing variations in the temperature distribution within the substrate surface.

However, since Patent Document 1 aims to prevent the resistance heating element from increasing in resistance and breaking when the ceramic heater is used for a long period of time by repeatedly subjecting it to heating-cooling cycles, it is not possible to sufficiently carbonize the Mo mesh electrode. Patent Document 2 aims to improve the change in resistance during repeated heating and cooling tests, so it is not possible to sufficiently carbonize the Mo mesh electrode.

Patent Document 3 aims to provide a ceramic heater that has small variation in the resistance value of the heater electrode layer within the substrate and can uniformly heat a semiconductor wafer, but the technology uses a conductive paste containing tungsten monocarbide particles to prevent the generation of ditungsten monocarbide, and when this technology is applied to a Mo mesh electrode, it is not possible to sufficiently carbonize the Mo mesh electrode.

The inventors discovered that Mo mesh electrodes can be sufficiently carbonized by coating them with C and subjecting them to heat treatment at an appropriate temperature, in addition to the C components that are mixed in from the binder of the ceramic raw materials, the carbon jig, and the environment, and thus completed the present invention.

In other words, the present invention has been made in consideration of the above circumstances, and aims to provide an electrode embedding member, a manufacturing method thereof, and a substrate holding member that can increase the resistance of an electrode without compromising the reliability of the electrode, increase the degree of freedom in electrode design, and suppress variation in the resistance value of the electrode within the substrate surface.

(1) In order to achieve the above object, the present invention provides an electrode-embedded member comprising a flat base made of a ceramic sintered body, and an electrode formed of a mesh woven with wires and embedded in the base, the electrode being made of a bulk of Mo carbide , and further comprising a connection member containing W metal embedded in the base and electrically connected to the electrode, the connection member having a W carbide layer on its surface .

In this way, by forming the electrode from a bulk of Mo carbide (Mo ₂ C), the volume resistivity becomes high, so that the resistance of the electrode can be increased without compromising the reliability of the electrode, and the degree of freedom in electrode design can be increased. Also, the variation in the resistance value of the electrode in the plane can be suppressed.

(2) As described above , the electrode-embedded member of the present invention further comprises a connection member electrically connected to the electrode and containing W metal embedded in the base, and the connection member has a W carbide layer on its surface.

In this way, by constructing the connection member electrically connected to the electrode from a material containing W metal and having a W carbide layer on the surface, it is possible to prevent the connection member from becoming highly resistive, improve the reliability of the electrical connection with the connection member, and also prevent the connection member from becoming embrittled, thereby reducing the risk of cracks occurring in the connection member.

(3) In addition, in the electrode embedding member of the present invention, the wire diameter of the wire forming the mesh of the electrode is 0.02 mm or more and 0.15 mm or less.

This makes it easier to design the electrode resistance to a high value, allowing greater freedom in electrode design. It also makes it possible to shorten the heat treatment time relatively, reducing manufacturing costs.

(4) The substrate holding member of the present invention is characterized by comprising an electrode-embedded member according to any one of (1) to (3) above, and a terminal electrically connected to the electrode.

This allows for the creation of a substrate holding member using an electrode-embedded member that allows for a high degree of freedom in electrode design and suppresses variation in the resistance value of the electrodes within the surface.

(5) 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 coated with carbon, a precursor formation process for combining the electrode and the plurality of ceramic degreased bodies to form an electrode-embedded member precursor formed in a flat plate shape with an electrode embedded therein, a heat treatment process for heat-treating the electrode-embedded member precursor at 800°C to 1500°C for 7 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 electrode during the heat treatment process, allowing the electrode to be constructed from a bulk of Mo carbide. As a result, the volume resistivity of the electrode material increases, making it possible to increase the resistance of the electrode even with a design that does not impair the reliability of the electrode, thereby increasing the degree of freedom in electrode design. In addition, it is possible to suppress variation in the resistance value of the electrode within the surface.

According to the present invention, the electrode of the electrode-embedded member is made of a bulk of Mo carbide, which increases the volume resistivity. This allows the electrode resistance to be increased even with a design that does not impair the reliability of the electrode, thereby increasing the degree of freedom in electrode design. In addition, the variation in the resistance value of the electrode within the surface can be suppressed.

FIG. 2 is a cross-sectional view showing an example of an electrode-embedded member according to the embodiment. 11 is a cross-sectional view showing a modified example of an electrode-embedded member according to the embodiment. FIG. 2 is a cross-sectional view showing an example of a substrate holding member according to an embodiment. FIG. 11 is a cross-sectional view showing a modified example of the substrate holding member according to the embodiment. FIG. 4 is a flowchart showing a method for manufacturing an electrode-embedded member according to the embodiment. 3A to 3D are cross-sectional views each showing a schematic diagram of a step in the manufacturing process of an electrode-embedded member according to an embodiment. 5A to 5C are cross-sectional views each showing a schematic diagram of a stage in a manufacturing process of a substrate holding member according to an embodiment. 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.

[Embodiment]
[Configuration of electrode-embedded member]
First, the configuration of an electrode-embedded member according to the present embodiment will be described. Fig. 1 is a cross-sectional view showing an example of an electrode-embedded member according to an embodiment of the present invention. The electrode-embedded member 100 according to the present embodiment includes a base body 110 and an electrode 120. The electrode-embedded member 100 is applied to heaters, electrostatic chucks, etc.

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 formed of a mesh with woven wires and is embedded in the base 110. The wires forming the mesh preferably have a wire diameter of 0.02 mm or more and 0.15 mm or less. This makes it easier to design the resistance of the electrode to a high value, allowing for greater freedom in electrode design. In addition, the heat treatment time can be relatively shortened, reducing manufacturing costs. Mo has a high melting point and is difficult to process, so wires with a wire diameter of less than 0.02 mm are difficult to manufacture. In addition, if a mesh is formed by weaving wires with a wire diameter of more than 0.15 mm, it may be difficult to increase the resistance value and design the required resistance value.

Furthermore, if the wire diameter is greater than 0.15 mm, there is a high risk of the wire cracking during sintering. Also, if the thickness of the mesh at the wire intersection is greater than 0.3 mm, there is an increased risk of cracking in the insulating layer when the ceramics on the top of the electrode 120 are configured as a thin insulating layer. In this way, by configuring the electrode 120 with a sufficiently thin wire, it is possible to further reduce the risk of the wire cracking during sintering, and even if the ceramics on the top of the electrode 120 are configured as a thin insulating layer, it is possible to further reduce the risk of cracking in the insulating layer.

The electrode 120 is made of a bulk body of Mo carbide (Mo ₂ C). In this way, by making the electrode 120 of Mo carbide, the volume resistivity can be increased. In addition, by making the electrode 120 of a bulk body, the risk of disconnection can be reduced even when the width of the electrode 120 is designed to be narrow, compared to an electrode made by firing a paste of an electrode material, and the reliability of the electrode 120 can be increased. That is, by making the electrode 120 of a bulk body of Mo carbide, the volume resistivity is high, the reliability is not impaired even when the width of the electrode is narrowed, and the variation in the resistance in the plane is unlikely to occur, so the resistance of the electrode 120 can be increased and the degree of freedom in the electrode design can be increased.

The electrode 120 is composed of Mo carbide when an elemental mapping analysis is performed on the entire cross section of the electrode 120 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 being made of a bulk body means that the porosity of the electrode 120 is 5% or less. The porosity of the electrode 120 can be measured, for example, by photographing a cross section of the electrode 120 with a scanning electron microscope (SEM) at a magnification of 1000 to 5000 times, and then binarizing a 30 μm x 30 μm field of view from the photographed data using free software "ImageJ" developed by the National Institutes of Health (NIH). Note that five fields of view can be observed at random as measurement points.

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 electrode-embedded member 100 may further include a connection member 130. FIG. 2 is a cross-sectional view showing a modified example of the electrode-embedded member according to the embodiment. 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, and allows for a stable supply of electricity. The connection member 130 preferably 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 analysis.

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.

The connection member 130 may have a W carbide layer on the surface. In that case, the W carbide layer is preferably greater than 0 μm and less than 20 μm. In this way, by configuring the connection member 130 to have a W carbide layer on the surface and making the thickness very thin, it is possible to suppress the connection member 130 from becoming highly resistant, further improving the reliability of the electrical connection via the connection member 130, and suppressing embrittlement of the connection member 130, thereby reducing the risk of cracks occurring in the connection member 130. In the manufacturing method of the present invention, the heat treatment temperature is relatively lower than the temperature at which carbonization of W progresses, so carbonization of W is less likely to progress, and even if the connection member 130 made of W is embedded, the W carbide layer on its surface can be made thin.

The electrode embedding member of the present invention has a high volume resistivity due to the electrode being made of a bulk of Mo carbide, so the electrode resistance can be increased even with a design that does not impair the reliability of the electrode, allowing for greater freedom in electrode design and suppressing variation in the resistance value of the electrode within the surface.

[Configuration of the substrate holding member]
FIG. 3 is a cross-sectional view showing an example of a substrate holding member according to an embodiment of the present invention. FIG. 4 is a cross-sectional view showing a modified example of the substrate holding member according to the embodiment. The substrate holding member 200 according to the present embodiment is provided with a terminal hole 142 in the electrode embedding member 100 according to the present embodiment and is provided with a terminal 140. The terminal 140 is electrically connected to the electrode 120. The terminal 140 is electrically connected to the electrode 120 includes both the terminal 140 being directly connected to the electrode 120 and the terminal 140 being connected to the electrode 120 via the connection member 130 or the like. This allows power to be supplied to the electrode 120. The terminal 140 can be formed of Ni or the like. The terminal 140 is brazed to the electrode 120 or the connection member 130 with Au brazing or the like. An intermediate member 150 formed of Kovar or the like may be provided between the electrode 120 or the connection member 130 and the terminal 140.

The substrate holding member of the present invention can increase the resistance of the electrodes even with a design that does not impair the reliability of the electrodes, allowing for greater freedom in electrode design and suppressing variation in the resistance value of the electrodes within the surface. In addition, when using an electrode embedding member that uses a connecting member, the risk of defective connection between the terminal and the connecting member can be reduced.

[Method of manufacturing electrode-embedded member]
Next, a manufacturing method of the electrode-embedded member according to the present embodiment will be described. FIG. 5 is a flow chart showing a manufacturing method of the electrode-embedded member according to the embodiment of the present invention. As shown in FIG. 5, the manufacturing method of the electrode-embedded member according to the 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. 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, it is important to coat the Mo electrode with C in the preparation step STEP 3 and the temperature and time of the heat treatment step STEP 5, and the other steps may be replaced with other methods.

Figures 6(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 6(a) to (d) show the case of manufacturing the electrode-embedded member of Figure 2.

In the compact formation step STEP 1, a plurality of ceramic compacts 11, 12 are formed from ceramic raw material powder. In FIG. 6, the ceramic compact is divided into two members, but it may be three or more depending on the design. For example, additives such as binder, plasticizer, dispersant, etc. 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 a plurality of ceramic compacts 11, 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 process described later. It is presumed that this C component also causes carbonization, but since the present invention promotes carbonization by coating the Mo mesh electrode with C, the amount of C component in the ceramic degreased body is not that important. Since the purpose of the present invention is to sufficiently carbonize the Mo of the electrode, there is no problem even if this amount of C component remains in the degreased body. If necessary, powders that act as sintering aids may be added to the ceramic raw material powder.

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 formed bodies 11, 12, the shape of the formed bodies may be adjusted by machining. Also, as shown in FIG. 6(b), a recess may be formed on one side of the ceramic formed body 12 (the joining surface with the other ceramic formed 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 formed body 11, or on both sides. The machining may be performed after degreasing.

In the degreasing step STEP 2, the multiple ceramic molded bodies 11, 12 are degreased at a predetermined temperature or higher for a predetermined time or longer to produce multiple 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 longer and 120 hours or shorter. An atmospheric furnace or a nitrogen atmosphere furnace can be used for degreasing.

In the preparation step STEP 3, an electrode 120 is prepared, which is made of a mesh woven with Mo wire and coated with carbon. Also, a connection member 130 is prepared as necessary.

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 a bulk of Mo carbide. The electrode 120 is prepared by processing the electrode 120 into a shape according to the design of the electrode embedding member 100. The shape is a mesh with wires woven in consideration of ease of carbonization. The wire diameter forming the mesh of the electrode 120 is preferably 0.02 mm or more and 0.15 mm or less.

It is preferable that 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 relatively less likely to carbonize than Mo 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 7 hours or more. As a result, the carbonization of Mo in the C-coated Mo mesh electrode 120 progresses, and the electrode becomes a bulk of Mo carbide. The heat treatment time may be a predetermined time according to the wire diameter of the Mo mesh electrode. For example, when the wire diameter is greater than 0.15 mm and less than or equal to 0.2 mm, the heat treatment time may be 20 hours. When using a connection member 130 containing W as a main component, the W in the connection member 130 is not easily carbonized regardless of the heat treatment time, since the heat treatment is performed at a temperature relatively lower than the temperature at which W carbonization progresses.

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 electrode 120 or the electrode 120 and the connection member 130 are embedded. The firing may be performed by increasing the temperature continuously from the heat treatment.

In this way, it is possible to increase the resistance of the electrode without compromising the reliability of the electrode, allowing for greater freedom in electrode design, and also to manufacture an electrode-embedded component that can suppress variation in the resistance value of the electrode within the surface.

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]
7(a) to 7(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. The terminal can be made of Ni or the like. The brazing material can also be Au brazing material or the like. An intermediate member 150 made of Kovar or the like may be placed between the connection member 130 and the terminal 140 and brazed. If the connection member 130 is not used, the terminal 140 is brazed directly to the electrode 120, or brazed to the electrode 120 via the intermediate member 150.

In this way, it is possible to manufacture a substrate holding member 200 that can increase the resistance of the electrodes even with a design that does not impair the reliability of the electrodes, that allows for greater freedom in electrode design, and that can suppress variation in the resistance value of the electrodes within the surface. Furthermore, when using an electrode embedding member that uses a connecting member, it is possible to manufacture a substrate holding member 200 that can reduce the risk of problems occurring in the connection between the terminals and the connecting member.

[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 produce 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. This was coated with carbon to a thickness of 1 μm by vacuum deposition to prepare an electrode. In addition, two connecting members with a size of φ8 mm x 0.2 mmt were produced 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 produce 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 7 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 5 mm diameter, 2 mm thick Kovar buffer member (intermediate member) and a 5 mm diameter, 30 mm long cylindrical Ni power supply terminal were installed on the exposed bottom surface of the connection member via brazing material, and brazing was performed at 1050°C with Au-Ni 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, the electrode used in Example 1 was changed to an electrode in which the wire diameter of the mesh was 0.03 mm. Otherwise, the substrate holding member of Example 2 was produced under the same conditions as Example 1.

Example 3
In Example 3, the electrode used in Example 1 was changed to an electrode in which the wire diameter of the mesh was 0.15 mm. Otherwise, the substrate holding member of Example 3 was produced under the same conditions as Example 1.

Example 4
In Example 4, the electrode used in Example 1 was changed to a Mo mesh electrode coated with carbon to a thickness of 1 μm by DLC (Diamond-like Carbon) coating. Otherwise, a substrate holding member of Example 4 was produced under the same conditions as Example 1.

Example 5
In Example 5, the electrode used in Example 1 was changed to a Mo mesh electrode coated with carbon to a thickness of 10 μm by carbon spraying. Otherwise, a substrate holding member of Example 5 was produced under the same conditions as in Example 1.

Example 6
In Example 6, the electrode used in Example 1 was changed to an electrode in which a Mo mesh electrode was coated with graphite having a thickness of 10 μm, the graphite being obtained by pyrolyzing methane gas at 2000° C. A substrate holding member for Example 6 was produced under the same conditions as in Example 1 except for the above.

(Example 7)
In Example 7, the electrode used in Example 1 was changed to an electrode in which the wire diameter of the mesh was 0.2 mm, and the heat treatment time was changed to 20 hours. Otherwise, the substrate holding member of Example 7 was produced under the same conditions as Example 1.

(Comparative Example 1)
In Comparative Example 1, the electrode used in Example 1 was changed to a Mo mesh electrode not coated with carbon. Otherwise, the substrate holding member of Comparative Example 1 was produced under the same conditions as in Example 1.

(Comparative Example 2)
In Comparative Example 2, the electrode used in Example 1 was changed to an electrode in which the wire diameter of the mesh was 0.2 mm, and the heat treatment time was changed to 14 hours. Otherwise, the substrate holding member of Comparative Example 2 was produced under the same conditions as in Example 1.

[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 heater resistance and 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. In addition, the resistance value of the entire heater electrode was measured.

(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 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).

(Measurement of Electrode Porosity)
The porosity of the electrode was measured by photographing the cross section of the electrode with a scanning electron microscope (SEM) at 1000 times magnification, and binarizing a 30 μm × 30 μm field of view from the photographed data using free software "ImageJ" developed by the National Institutes of Health (NIH). Five fields of view were randomly selected as measurement points and observed. When the porosity was 5% or less, it was determined to be a bulk body.

In Examples 1 to 7, Mo carbide was found all the way to the center of the electrode at all three measured locations by both EPMA and XRD. It was also confirmed that the electrode was a bulk body. As a result, the variation in resistance of the heater electrode was suppressed, and the surface temperature distribution was also suppressed accordingly. From the results of Examples 1 and 2, it was found that when the wire diameter was 0.1 mm or less, the electrode could be completely carbonized by heat treatment for 7 hours. On the other hand, from the results of Examples 4 and 7, it was found that when the wire diameter was 0.15 mm, heat treatment for 14 hours was required, and when it was 0.2 mm, heat treatment for 20 hours was required.

The results of Examples 1, 4, 5, and 6 also showed that the C coating method did not affect the carbonization of the Mo mesh electrode. It was also found that a C coating thickness of 1 μm was sufficient.

In Comparative Examples 1 and 2, the electrode closest to the center of the mounting surface had a mixed structure of Mo and Mo ₂ C. As a result, it is believed that the resistance of the heater electrode varied, and the surface temperature distribution became larger accordingly. Comparative Example 1 was produced using the conventional method, but due to a shortage of carbon source, the electrode was not completely carbonized and had a mixed structure of Mo and Mo ₂ C.

In Comparative Example 2, a comparison with Example 7 shows that although the carbon source was sufficient, the wire diameter was large and the heat treatment time was insufficient to carbonize the center. Therefore, if the wire diameter is 0.1 mm or less, the electrode can be carbonized with the same heat treatment time as before, and if the wire diameter is 0.15 mm or less, although the heat treatment time is longer than the conventional heat treatment time, the electrode can be carbonized with a heat treatment time that is commensurate with the effect, and therefore manufacturing costs can be reduced.

As a result, it was confirmed that in Examples 1 to 7, the electrodes were able to be carbonized sufficiently compared to Comparative Examples 1 and 2, and the variation in the resistance of the heater electrodes was suppressed, and the surface temperature distribution was accordingly suppressed to a small extent. It was also 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 200 Substrate holding member

Claims (4)

An electrode embedding member,
A flat plate-shaped base body made of a ceramic sintered body;
an electrode formed of a mesh of woven wires and embedded in the substrate;
The electrode is made of a bulk of Mo carbide ,
A connection member including a W metal electrically connected to the electrode and embedded in the base body is further provided,
The connection member has a W carbide layer on a surface thereof . 2. The electrode-embedding member according to claim 1, wherein the wire diameter of the wire forming the electrode mesh is 0.02 mm or more and 0.15 mm or less. The electrode-embedding member according to claim 1 or 2,
and a terminal electrically connected to the electrode. A method for manufacturing an electrode-embedded member made 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 of woven Mo wires and coated with carbon;
The electrode and the plurality of ceramic degreased bodies are combined to form a flat plate,
a precursor forming step of forming an electrode-embedded member precursor having an electrode embedded therein;
a heat treatment step of heat treating the electrode-embedded member precursor at 800° C. or more and 1500° C. or less for 7 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.

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