JP2020155449A - Manufacturing method of electrode embedded member - Google Patents

Abstract

To provide a manufacturing method of an electrode embedded member capable of stabilizing characteristics of an electrode constituted of a mesh body.SOLUTION: The present invention relates to a manufacturing method of an electrode embedded member 10 comprising a substrate 1 constituted of ceramics and an electrode 2 constituted of a mesh body embedded in the substrate 1. The manufacturing method includes: an electrode heat treatment step STEP1 of applying a heat treatment to the mesh body which is configured by weaving a wire constituted of molybdenum, tungsten or an alloy containing them as main components at a temperature equal to or higher than 900°C and lower than a recrystallization temperature of the wire and in a reduction atmosphere; an electrode cut step STEP3 of cutting the mesh body in a shape of the electrode 2; and a calcination step STEP4 of heating the mesh body at a temperature equal to or higher than the recrystallization temperature in a state where the cut mesh body to which the heat treatment is applied, is embedded in a ceramic powder to be the substrate 1, in a ceramic mold formed by molding the ceramic powder, in a defatted body formed by defatting the ceramic mold or in a calcined body formed by calcinating the ceramic mold or the defatted body.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for manufacturing an electrode-embedded member in which an electrode is embedded in a substrate.

In semiconductor manufacturing equipment, electrostatic chucks that hold substrates such as wafers on the surface, heaters that heat the substrates placed on the surface, susceptors, etc. are electrode-embedded members in which electrodes are embedded inside a substrate made of ceramics. It has.

In particular, in the electrode-embedded member provided in the heater, the electrode (heater electrode) that functions as a heating element is made of a mesh body (mesh body) made of Mo (molybdenum) or W (tungsten) cut into a predetermined shape. I often do it.

Further, Patent Document 1 discloses that the internal electrode of the electrostatic chuck is used as a mesh-like electrode (wire mesh-like electrode), and a large attractive force is stably exhibited by applying pressure in the thickness direction to plastically deform the electrode. Has been done. Further, Patent Document 2 discloses that an electrode functioning as a heating element is made by rolling a net-like material made of Mo, W or the like.

Further, Patent Document 3 describes the number of crystal grains having a desired aspect ratio by heating the Mo wire rod from 900 ° C. to 1200 ° C. in a non-oxidizing atmosphere to remove oxides on the surface. It is disclosed to ensure tensile strength, elongation, and number of bends.

Japanese Patent No. 3359582 JP-A-11-204238 Japanese Patent No. 5068986

For example, when the electrode is made to function as a heating element and the electrode-embedded member is configured as a heater from the above-mentioned conventional mesh-like body, individual differences in heater characteristics are large, and a desired temperature distribution may not be obtained. ..

The inventor has found that the cause of this is an unstable contact state at the intersection of the wires of the electrode, a local excessive deformation of the wire at the intersection, and a deformation such as bending over the entire electrode.

In order to eliminate the unstable contact state at the intersection of the wire rods, a large pressure may be applied in the thickness direction of the electrode with reference to Patent Documents 1 and 2 above. However, this may cause local excessive deformation of the wire rod at the intersection, and further cause cracks or the like in the wire rod to cause disconnection.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for manufacturing an electrode embedded member capable of stabilizing the characteristics of an electrode made of a mesh-like body.

The present invention is a method for manufacturing an electrode-embedded member including a substrate made of ceramics and an electrode made of a network-like body embedded inside the substrate, which is made of molybdenum, tungsten or an alloy containing these as main components. A step of heat-treating a network formed by weaving a wire in a reducing atmosphere at a temperature of 900 ° C. or higher and lower than the recrystallization temperature of the wire, a step of cutting the network into the shape of the electrode, and the above-mentioned In the ceramic powder to be the base, in the ceramic molded body formed by molding the ceramic powder, in the degreased body obtained by degreasing the ceramic molded body, or by calcining the ceramic molded body or the degreased body. It is characterized by comprising a step of heating the network at a temperature equal to or higher than the recrystallization temperature in a state where the heat treatment and the cut network are embedded in the body.

According to the present invention, it is possible to stabilize the characteristics of the electrode in the electrode-embedded member by heat-treating the network at 900 ° C. or higher and lower than the recrystallization temperature of the wire rod in a reducing atmosphere. ..

This was found by the inventor based on Examples and Comparative Examples described later, and the reason is not clear, but as a result of heat treatment at a temperature lower than the recrystallization temperature, the microstructure is not significantly changed. (Relative change is much smaller than recrystallization), mainly because some of the residual stress generated when weaving the wire is removed in the same way as annealing and normalizing. ..

Further, by heat-treating the network in a reducing atmosphere, the natural oxide film formed at the contact points between the wires constituting the network is reduced. As a result, the contact resistance between the wires is reduced and the resistance distribution in the plane of the network is stabilized. Further, since the mesh-like body after the heat treatment is distorted and has a flat shape, it is possible to obtain an electrode having a desired shape with high dimensional accuracy when the mesh-like body is cut after the heat treatment. On the other hand, when the heat treatment is performed after cutting the mesh-like body, it is possible to remove the processing strain at the time of cutting.

If the heat treatment temperature is less than 900 ° C., the residual stress of the network is not sufficiently removed, and if the heat treatment temperature is the recrystallization temperature, recrystallization may proceed and the network may be weakened. Further, the natural oxide film at the contact point between the wires constituting the network is not sufficiently removed, and the resistance distribution in the plane may become unstable.

In the present invention, the step of pressing the heat-treated network in the thickness direction is provided, and the pressed network is pressed in the ceramic powder, in the ceramic molded body, in the degreased body, or in the calcined body. It is preferable to carry out the heating in a state of being embedded in.

Further, in the present invention, it is preferable to heat-treat the network and simultaneously press the network in the thickness direction.

In these cases, it is possible to stabilize the contact state of the wire rod of the network, alleviate the local excessive deformation of the wire rod, and further suppress the deformation and distortion of the entire mesh body. .. As a result, the characteristics of the electrode are stabilized.

Further, in the present invention, it is preferable that the average particle size of molybdenum or tungsten in the wire rod after heating is 1 μm or more and 100 μm or less.

In this case, since the average particle size is as small as 100 μm or less and the particle size is not coarsened, it is possible to further make the contact resistance uniform in the contact state of the wire rod of the electrode.

Further, in the present invention, when the cross section of the wire rod before pressing is circular with a diameter d, the pressing is performed so that the thickness at the intersection of the wire rods of the cut mesh body is 1.95 d or less. It is preferable to do so.

In this case, as can be seen from Examples and Comparative Examples described later, it is possible to further stabilize the intersection of the wire rods.

The schematic cross-sectional view which shows the electrode embedded member manufactured by the manufacturing method of the electrode embedded member which concerns on embodiment of this invention. The flowchart which shows the manufacturing method of the electrode embedded member which concerns on embodiment of this invention. An enlarged schematic partial cross-sectional view of an electrode of an electrode embedded member.

The manufacturing method of the electrode embedded member 10 according to the embodiment of the present invention will be described with reference to the drawings. It should be noted that each drawing is deformed in order to clarify the electrode embedded member 10, the constituent elements, and the like, and does not represent the actual ratio, and the directions such as up and down are merely examples.

As shown in FIG. 1, the electrode-embedded member 10 manufactured by the method for manufacturing the electrode-embedded member 10 according to the embodiment of the present invention is made of a substrate 1 made of ceramics and a mesh-like body embedded inside the substrate 1. The electrode 2 is provided. The electrode embedded member 10 is used, for example, in a heater in a semiconductor manufacturing apparatus, and in this case, the electrode 2 functions as a heater electrode.

However, the electrode burying member 10 is not limited to the one used for the heater, and may be used for an electrostatic chuck, a susceptor, or the like. In this case, the electrode 2 is an electrostatic adsorption electrode, a high frequency generation electrode, or the like. Functions as. Further, a plurality of electrodes 2 may be embedded in the electrode embedded member 10, and these plurality of electrodes 2 may have the same function or may have different functions.

As shown in FIG. 2, this manufacturing method includes an electrode heat treatment step STEP1, an electrode pressing step STEP2, an electrode cutting step STEP3, and a firing step STEP4.

In the electrode heat treatment step STEP1, a network formed of a wire rod made of Mo (molybdenum), W (tungsten) or an alloy containing these as a main component is reduced at a temperature of 900 ° C. or higher and lower than the recrystallization temperature of the wire rod. This is a process of heat treatment in an atmosphere. The reducing atmosphere is, for example, an atmosphere composed of hydrocarbon gases such as H ₂ (hydrogen), CO (carbon monoxide), CH ₄ (methane), C ₃ H ₈ (propane), and C ₄ H ₁₀ (butane). is there. The alloy containing Mo and W as main components generally refers to an alloy having a total content of Mo and W of 50% by weight or more, preferably 70% by weight or more, and more preferably 80% by weight. % Or more.

The recrystallization temperature of Mo and Mo alloy is about 1000 ° C to 1200 ° C. For example, the recrystallization temperature of TZM alloy in which Mo is doped with Ti (titanium), zirconia (ZrO ₂ ) and C (carbon) is It is about 1300 ° C. The recrystallization temperature of W and W alloy is higher than that of Mo and Mo alloy. Therefore, in the electrode heat treatment step STEP1, the network may be heat-treated at 900 ° C. or higher and 1200 ° C. or lower, preferably 900 ° C. or higher and 1000 ° C. or lower.

The mesh-like body is preferably made of plain weave, but may be made of other weaves such as twill weave, tatami mat weave, and twill tatami weave.

Based on Examples and Comparative Examples described later, the inventor heat-treats the network at a temperature of 900 ° C. or higher and lower than the recrystallization temperature of the wire rod in a reducing atmosphere to develop the characteristics of the electrode 2 in the electrode embedded member 10. It was found that it is possible to stabilize the temperature.

The reason is not clear, but as a result of heat treatment at a temperature lower than the recrystallization temperature, the microstructure is mainly woven without significantly changing (relative change is significantly smaller than that of recrystallization). It is considered that this is because a part of the residual stress generated at that time is removed. If the heat treatment temperature is less than 900 ° C., the residual stress of the network is not sufficiently removed, and if the heat treatment temperature is the recrystallization temperature, recrystallization may proceed and the network may be weakened. Further, it is considered that the heat-treated mesh-like body has small deformation and distortion, and it is possible to cut the mesh-like body into a desired electrode 2 shape with high dimensional accuracy in the electrode cutting step STEP3 described later. ..

The electrode pressing step STEP2 is a step of pressing the heat-treated mesh-like body in the thickness direction. By pressing the heat-treated mesh-like body in the thickness direction in this way, the wires are surely brought into contact with each other over a wide range at the intersections of the wires, so that the contact state of the wires is further stabilized. It becomes possible.

With reference to FIG. 3, when the cross section of the wire rod before pressing is circular with a diameter d, pressing is performed so that the thickness t at the intersection of the wire rods of the cut mesh-like body is 1.95 d or less. preferable. As a result, as can be seen from Examples and Comparative Examples described later, it is possible to further stabilize the intersection of the wire rods. When pressing, a method of placing a heavy stone or a method of uniaxial pressing can be used.

The cross section of the wire rod before pressing is the cross section of the wire rod in the portion where the cross section is not deformed by the intersection during the intersection portion, and means the cross section of the wire rod before weaving. The cross section of the wire rod is not limited to a circular shape, and may be substantially or roughly circular, or may be an elliptical shape, or a high polygonal shape such as a hexagon or an octagon.

Further, the electrode heat treatment step STEP1 and the electrode pressing step STEP2 may be performed simultaneously or partially at the same time. That is, the mesh-like body may be pressed in the thickness direction simultaneously or partially at the same time as the heat treatment of the network-like body. In this case, using a hot press furnace, _{N 2} atmosphere, it is preferable to pressurize a pressure 1MPa～10MPa.

By heat-treating the mesh-like body while pressing in this way, the contact state of the wire rod of the mesh-like body is stabilized, the local excessive deformation of the wire rod is alleviated, and the deformation of the entire mesh-like body is suppressed. It will be possible to further improve the system. However, the electrode pressing step STEP2 does not necessarily have to be performed and may be omitted.

The electrode cutting step STEP3 is a step of cutting the heat-treated mesh-like body to obtain an electrode 2 made of the mesh-like body having a predetermined shape. Cutting can be performed, for example, by laser processing.

The firing step STEP4 is performed in the ceramic powder to be the substrate 1, in the ceramic molded body formed by molding the ceramic powder, in the degreased body obtained by degreasing the ceramic molded body, or by calcining the ceramic molded body or the degreased body. A substrate 1 made of a ceramic sintered body in which an electrode 2 is embedded is formed by heating the mesh-like body at a temperature equal to or higher than the recrystallization temperature in a state where the heat-treated and cut mesh-like body is embedded in the calcined body. This is the process of obtaining.

Ceramic powder, for example, aluminum nitride (AlN), yttrium oxide _(Y 2 _{O 3)} in which the like is added.

When a ceramic molded body is used, for example, a plurality of plate-shaped ceramic molded bodies are prepared by molding the ceramic raw material by a cold isostatic pressing method (CIP). Specifically, for example, a binder, a plasticizer, a sintering aid, a dispersant and the like are added to the above ceramic powder, mixed with a solvent, and then spray-dried to obtain ceramic granules. Then, an ingot is obtained by CIP molding the ceramic granules, and the ingot is machined to form a predetermined outer shape to produce a ceramic molded body.

When a degreased body is used, the degreased body is produced by performing a degreasing treatment by heating the above-mentioned ceramic molded product at a temperature of 500 ° C. or higher and lower than 900 ° C. When a calcined body is used, the calcined body is produced by calcining the above-mentioned ceramic molded body or degreased body at a temperature of 900 ° C. or higher and lower than the recrystallization temperature of the wire rod.

When embedding a network in a ceramic molded body, a plurality of ceramic molded bodies are prepared, and the surface of at least one of the ceramic molded bodies has a shape along the outer shape of the meshed body by machining. A plurality of ceramic molded bodies may be laminated in a state where a recess is formed and a mesh-like body is housed in the recess. In this case, it is preferable that the direction in which the plurality of ceramic molded bodies are laminated is the thickness direction of the mesh-like body, and heating is performed while pressurizing in this thickness direction. When a degreased body or a calcined body is used instead of the ceramic molded body, it may be embedded, laminated, and heated in the same manner as the ceramic molded body.

When the mesh-like body is housed in the recess, it is desirable that the depth of the recess is about the same as the thickness of the mesh-like body. This is because if the recess is too shallow, the mesh-like body may be excessively crushed, and if the recess is too deep, a recess may be formed in the upper part of the mesh-like body.

In the case of the powder hot press method, it is not necessary to perform degreasing treatment and calcining, and a ceramic molded product is produced by filling a mold with ceramic powder and then performing uniaxial pressurization. After that, the ceramic powder may be filled in the ceramic molded body on which the mesh-like body is placed, and the mesh-like body may be embedded in the ceramic powder by uniaxially pressing at a pressure of 1 MPa or more and 20 MPa or less. In this case, the pressurizing direction is preferably performed in the thickness direction of the network.

The inventor has found that the electrode 2 is deformed due to an unstable contact state of the wire rod at the intersection of the electrode 2 made of a mesh-like body, a local excessive deformation of the wire rod at the difference portion, and a deformation such as bending over the entire electrode 2. It has been found that the characteristics such as the heater characteristics are affected, and the problem that the desired temperature distribution cannot be obtained on the surface of the substrate 1 occurs.

On the other hand, as can be seen from the examples described later, if the inventor heat-treats the network in a reducing atmosphere at a temperature of 900 ° C. or higher and lower than the recrystallization temperature, the principle is only speculation, but normalizing Similar to normalizing, it was found by removing the residual stress due to the structural change due to thermal stress.

The average particle size of molybdenum or tungsten in the wire rod after the firing step STEP4 is preferably 1 μm or more and 100 μm or less. This is because if the average particle size is as small as 100 μm or less and the particle size is not coarse, it is possible to make the contact resistance of the wire rod of the electrode 2 uniform in the contact state.

(Example 1)
Aluminum nitride (AlN) yttrium oxide as a sintering aid powder 95% by weight of (Y ₂ O ₃ was added 5 wt%, were mixed with a binder and a solvent, to obtain a ceramic granules by spray-drying drying Then, the ceramic granules were CIP-molded at a pressure of 98 MPa (1 ton / cm ² ) to obtain an ingot of a ceramic molded body. Next, the ingot was machined to have a diameter of 370 mm and a thickness of 5 mm. A plurality of disc-shaped members having a thickness of ~ 20 mm were obtained. At this time, a recess having a depth of 0.2 mm for accommodating the electrode 2 was formed on the surface of the disc-shaped member. A plurality of degreased bodies were obtained by degreasing in an atmosphere at a temperature of 500 ° C. or higher for 2 hours.

After heat-treating the electrode 2 and arranging the cut mesh-like body in the recess of the degreased body, a laminated body was obtained by laminating a plurality of degreased bodies so as to sandwich the mesh-like body. Carbon type of arranging the laminated body inside placed in a hot press furnace, while pressurized with 1MPa or more pressure in the laminating direction of the laminate was fired by keeping the furnace temperature 1800 ° C. for 2 hours in N ₂ atmosphere, A ceramic sintered body was obtained. Then, by grinding and polishing the surface of the ceramics sintered body, a terminal hole for connecting the electrode 2 embedded in the ceramics sintered body and an external power source is formed, and then the electrode 2 and the terminal are formed in the terminal hole. The electrode embedded member 10 was manufactured by brazing.

Here, for the mesh-like body to be the electrode 2, a wire rod having a diameter d of 0.1 mm made of Mo having a recrystallization temperature of about 1200 ° C. is used, and the mesh size is 50 made of 50 wires per inch. A plain weave was used.

Then, after the mesh-like body is heat-treated at 1000 ° C. in a hydrogen atmosphere, the network-like body is cut into a predetermined pattern by laser processing, so that the resistance value at room temperature is 6.02Ω and it functions as a heating element. Electrode 2 was obtained.

The produced electrode-embedded member 10 supplies power to the electrode 2 from an external power source, and after the temperature of the electrode-embedded member 10 becomes steady, the temperature distribution on the surface is measured with an IR camera, and the temperature in a predetermined measurement region having a diameter of 300 mm is measured. The difference between the maximum and minimum values of was measured as the temperature distribution.

Further, after the temperature distribution was measured, the electrode embedded member 10 was cut, and image processing was performed in a field view magnified 500 times or 1000 times the cross section of the electrode 2, so that the average particle size of the electrode 2 was measured. The results are summarized in Table 1.

(Example 2)
The electrode-embedded member 10 of Example 2 was produced according to the same method as that of Example 1 except that the network body to be the electrode 2 was cut into a predetermined pattern having a resistance value of 5.45 Ω at room temperature.

(Example 3)
That thickness t of the intersection of the wire rod under a N ₂ atmosphere using a hot press furnace were subjected to a heat treatment while pressing so as to 0.185mm when a reticulated body serving as an electrode 2 is subjected to heat treatment at 1000 ° C. Except, the electrode-embedded member 10 of Example 3 was produced according to the same method as that of Example 1.

(Example 4)
The electrode-embedded member 10 of Example 4 was used in the same manner as in Example 1 except that a wire rod made of W having a recrystallization temperature of about 1200 ° C. was used as the network body to be the electrode 2. Was produced.

(Example 5)
The electrode-embedded member 10 of Example 5 was produced in the same manner as in Example 1 except that the reticulated body to be the electrode 2 was heat-treated at 900 ° C.

(Example 6)
The same as in Example 1 except that a wire rod made of W to which 300 ppm of K (potassium) added at a recrystallization temperature of about 1200 ° C. was used as the network body to be the electrode 2. The electrode-embedded member 10 of Example 6 was produced according to the method.

(Comparative Example 1)
The electrode embedded member 10 of Comparative Example 1 was cut into the same pattern as in Example 1 according to the same method as in Example 1 except that the mesh-like body to be the electrode 2 was not heat-treated. Was produced.

(Comparative Example 2)
The electrode embedded member 10 of Comparative Example 1 was cut into the same pattern as in Example 2 according to the same method as in Example 1 except that the mesh-like body to be the electrode 2 was not heat-treated. Was produced.

(Comparative Example 3)
The electrode embedded member 10 of Comparative Example 3 was produced according to the same method as in Example 1 except that the reticulated body to be the electrode 2 was heat-treated at 700 ° C.

By comparing Example 1 and Comparative Example 1 and Example 2 and Comparative Example 2, it was confirmed that the temperature distribution on the surface of the electrode embedded member 10 was reduced by performing the heat treatment of the network.

By comparing Example 5 and Comparative Example 3, it was confirmed that the effect of reducing the temperature distribution on the surface of the electrode embedded member 10 becomes remarkable by heat-treating the network at 900 ° C. or higher.

By comparing Example 5 and Example 6, it was confirmed that when the average particle size of the wire rod is 1 μm or more and 100 μm or less, the temperature distribution on the surface of the electrode embedded member 10 is further reduced.

By comparing Example 1 and Example 3, it was confirmed that the electrode pressing step STEP2 has the effect of further reducing the temperature distribution on the surface of the electrode embedded member 10.

1 ... Base, 2 ... Electrode, 10 ... Electrode embedded member.

Claims (5)

A method for manufacturing an electrode-embedded member including a substrate made of ceramics and an electrode made of a mesh-like body embedded inside the substrate.
A step of heat-treating a network formed of a wire rod made of molybdenum, tungsten, or an alloy containing these as a main component in a reducing atmosphere at a temperature of 900 ° C. or higher and lower than the recrystallization temperature of the wire rod.
A step of cutting the network into the shape of the electrode, and
In the ceramic powder serving as the substrate, in the ceramic molded body obtained by molding the ceramic powder, in the degreased body obtained by degreasing the ceramic molded body, or temporarily baking the ceramic molded body or the degreased body. A method for producing an electrode-embedded member, which comprises a step of heating the network at a temperature equal to or higher than the recrystallization temperature in a state where the heat treatment and the cut network are embedded in the burnt body. .. A step of pressing the heat-treated network in the thickness direction is provided.
The electrode according to claim 1, wherein the pressed mesh body is heated while being embedded in the ceramic powder, the ceramic molded body, the degreased body, or the calcined body. Manufacturing method of buried members. The method for manufacturing an electrode-embedded member according to claim 1, wherein the mesh-like body is heat-treated and the mesh-like body is pressed in the thickness direction at the same time. The method for manufacturing an electrode-embedded member according to claim 2 or 3, wherein the average particle size of molybdenum or tungsten in the wire rod after heating is 1 μm or more and 100 μm or less. When the cross section of the wire rod before pressing is circular with a diameter d, the pressing is performed so that the thickness at the intersection of the wire rods of the cut mesh-like body is 1.95 d or less. The method for manufacturing an electrode embedded member according to claim 2 or 3.