JP7804479B2 - Electrode-embedding member and method for manufacturing the same - Google Patents

Description

The present invention relates to an electrode-embedding member and a method for manufacturing the same.

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 structure that includes a first metal member joined to a conductive member with brazing material and having an average linear expansion coefficient equal to or greater than that of the conductive member, one or more second metal members having an average linear expansion coefficient greater than that of the first metal member, and a metal terminal joined to the second metal member and having an average linear expansion coefficient greater than that of the second metal member, and that can prevent cracks from occurring in the ceramic substrate or conductive member even after long-term use.

Japanese Patent Application Laid-Open No. 2019-182683

As noted in Patent Document 1, conventionally, attention has been focused on the linear expansion coefficient of the materials that make up the electrode-embedded member, and soldering has been performed with a buffer material interposed between them. In other words, cracks in the terminal structure have been suppressed from a mechanical standpoint.

However, when electrode-embedded components with these structures are used in actual processes, oxygen from the environment causes oxidation to progress from the surface to the interior of the connecting and buffering components, causing a deterioration in the strength of these components themselves. In other words, strength deterioration occurs due to chemical corrosion. As a result, the strength of the terminal structure deteriorates, causing the terminal to fall off or poor electrical contact. Therefore, there is a demand for a terminal structure that can prevent such problems.

The inventors discovered that by including a specified amount or more of Fe in the brazing material, deterioration of the connecting members and buffer members is less likely to occur even when the electrode-embedding member is used in an oxygen-containing environment, and the strength of the terminal structure is less likely to decrease, leading to the completion of this invention.

In other words, the present invention was made in consideration of these circumstances, and aims to provide an electrode-embedding member that is less susceptible to deterioration of connecting members and buffer members and less likely to reduce the strength of the terminal structure, as well as a method for manufacturing the same.

(1) In order to achieve the above object, the present invention provides an electrode-embedding member comprising: a flat substrate made of a ceramic sintered body; an electrode embedded in the substrate; a connecting member electrically connected to the electrode and embedded in the substrate; a terminal for supplying electricity to the electrode; a buffer member disposed between the connecting member and the terminal; and a brazing material for fixing the buffer member and the terminal, wherein the brazing material is mainly composed of Au and contains 4 atoms% or more of Fe in a surface layer that is a region 20 μm or less from the surface of the brazing material , and an oxide of Fe is formed on the surface of the brazing material .

In this way, by including 4 atoms% or more of Fe in the surface layer of the brazing material after brazing, oxidation of the connecting members and buffer members is suppressed. As a result, deterioration in the strength of the connecting members and buffer members is suppressed, and the strength of the terminal structure is maintained.

In this way, the formation of Fe oxide on the surface of the brazing material further suppresses oxidation of the connecting members and buffer members.

( 2 ) In addition, in the electrode-embedding member of the present invention, the brazing filler metal is characterized in that, in the intensity ratio of characteristic X-rays of O and Fe obtained by EPMA analysis or EDX analysis of a cross section perpendicular to the surface of the brazing filler metal, the value at the surface of the brazing filler metal is at least twice the value inside the brazing filler metal.

In this way, the intensity ratio of the characteristic X-rays of O and Fe obtained by EPMA or EDX analysis of a cross section perpendicular to the surface of the brazing material shows that the value at the surface of the brazing material is at least twice the value inside the brazing material, thereby further suppressing oxidation of the connecting members and buffer members.

( 3 ) In the electrode-embedding member of the present invention, the buffer member contains Fe.

In this way, by including Fe in the buffer material, even if the brazing material does not contain Fe, Fe will dissolve into the brazing material during brazing, resulting in the brazing material containing Fe after brazing, which can be used as a raw material for oxide films, etc.

( 4 ) In addition, in the electrode embedding member of the present invention, the buffer member includes a first buffer member arranged on the connecting member side and a second buffer member arranged on the terminal side, and the second buffer member is characterized in that it has Fe as its main component.

In this way, by using a second buffer member whose main component is Fe, even if the brazing material does not contain Fe, the brazing material will contain a sufficient amount of Fe after brazing.

( 5 ) The method for manufacturing an electrode-embedding member of the present invention is a method for manufacturing an electrode-embedding member, comprising: a flat-plate-shaped substrate made of a ceramic sintered body; an electrode embedded in the substrate; and a connecting member electrically connected to the electrode and embedded in the substrate, the method comprising the steps of: preparing an electrode-embedding member precursor having a terminal hole formed therein through which at least a part of one main surface of the connecting member is exposed; preparing a buffer member and a terminal, and arranging the buffer member and the terminal in the terminal hole of the electrode-embedding member precursor; and preparing a brazing material mainly composed of Au, and arranging the buffer member and the terminal in the terminal hole. and a brazing step of brazing and fixing the buffer member and the terminal placed on the buffer member with the brazing material, wherein the components and size of the buffer member prepared in the placing step or the area in contact with the brazing material are adjusted, or the components of the brazing material prepared in the brazing step are adjusted , so that the brazing material after the brazing step contains 4 atoms% or more of Fe in a surface layer that is a region 20 μm or less from the surface of the brazing material, and the brazing material after the brazing step is heated to form an oxide of Fe on the surface of the brazing material .

In this way, the composition and size of the buffer material prepared in the placement process or the area in contact with the buffer material are adjusted, or the composition of the buffer material prepared in the brazing process is adjusted, so that the surface layer of the brazing material after the brazing process contains 4 atoms% or more of Fe. This allows an Fe oxide film to form on the surface of the brazing material (at the boundary with the external environment) during use of the electrode-embedding member, suppressing oxidation of the connecting member and buffer material. As a result, deterioration in the strength of the connecting member and buffer material is suppressed, and the strength of the terminal structure is maintained.

This invention makes it possible to construct an electrode-embedding component that is less susceptible to deterioration of connection members and buffer members, and less likely to reduce the strength of the terminal structure.

FIG. 2 is a cross-sectional view showing an example of an electrode-embedded member according to the embodiment. 2 is an enlarged partial cross-sectional view showing a terminal structure of the electrode-embedded member of FIG. 1. FIG. 10 is an enlarged partial cross-sectional view showing a terminal structure of a modified example of the electrode-embedding member according to the embodiment. FIG. 1 is a flowchart illustrating an example of a method for manufacturing an electrode-embedded member according to an embodiment. 1 is a flowchart illustrating an example of a method for manufacturing an electrode-embedded member according to an 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. 3A to 3C 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. 1 is a table showing the manufacturing 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, the same reference numbers will be used in each drawing to refer to the same components, and duplicate explanations will be omitted. Note that in the structural 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-embedding member according to this embodiment will be described. Fig. 1 is a cross-sectional view showing an example of an electrode-embedding member according to this embodiment. Fig. 2 is a partial cross-sectional view showing an enlarged terminal structure of the electrode-embedding member of Fig. 1. An electrode-embedding member 100 according to this embodiment includes a base 110, an electrode 120, a connecting member 130, a terminal 140, a buffer member 150, and a brazing material 160. The electrode-embedding member 100 is applicable to heaters, electrostatic chucks, etc.

The base 110 is made of a ceramic sintered body, is formed in a flat plate shape, and has a mounting surface 112 on one main surface for mounting a substrate. Various materials can be used for 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, such _as a disk, a polygonal shape, or an elliptical shape.

The electrode 120 is embedded in the substrate 110. The electrode 120 can be made of Mo, W, or the like. The electrode 120 is preferably made of a mesh woven with wire. The wire forming the mesh preferably has a diameter of 0.02 mm or more and 0.15 mm or less. By constructing the electrode 120 from sufficiently thin wire in this way, the risk of the wire cracking during sintering can be further reduced. Furthermore, even if the ceramic on top of the electrode 120 is constructed as a thin insulating layer, the risk of cracks occurring in the insulating layer can be further reduced.

The base 110 may be provided with 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.

The connection member 130 is electrically connected to the electrode 120 and embedded in the base 110. This allows electricity to be supplied to the electrode 120 via the connection member 130. The connection member 130 can be made of Mo, W, or the like.

The thickness of the connecting 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 drilling the terminal holes 142 for connecting the terminals 140 to the base 110. If it is more than 5 mm, because the connecting member 130 is embedded in the base 110, there is an increased risk of cracks occurring in the base 110 due to differences in the contraction rate between the connecting member 130 and the ceramic of the base 110 during firing and the thermal expansion rate during use.

The terminal 140 is connected to an external power source (not shown) and supplies electricity to the electrode 120. The terminal 140 can be made of Ni or other materials. The terminal 140 is electrically connected to and fixed in place by the brazing material 160 to the electrode 120, the connecting member 130, or the buffer member 150.

The buffer member 150 is disposed between the connection member 130 and the terminal 140. Disposed between the connection member 130 and the terminal 140 means that the buffer member 150 is disposed in an area of the electrode-embedding member 100 below the lower surface of the connection member 130 and above the upper end of the terminal 140. It is preferable that brazing material 160 be present between the lower surface of the connection member 130 and the upper surface of the buffer member 150, and between the lower surface of the buffer member 150 and the upper end of the terminal 140.

The buffer member 150 can be formed from, for example, W, Mo, Kovar, Invar, Super Invar, or Niresist. The thickness of the buffer member 150 is preferably 0.2 mm or more and 2 mm or less.

The connecting member 130 and the buffer member 150 may be made of the same material. By doing so, the connecting member 130 is embrittled because it is embedded in the base 110 and fired, but because there is almost no difference in the expansion coefficients between the connecting member 130 and the buffer member 150, stress is less likely to act on the connecting member 130, making the connecting member 130 less likely to break. On the other hand, although there is a difference in the expansion coefficients between the buffer member 150 and the terminal 140, the buffer member 150 is not fixed in position during brazing and is fluid, so stress is less likely to occur between the buffer member 150 and the terminal 140. This makes it possible to suppress cracks in the terminal structure from a mechanical standpoint.

The connecting member 130 and the buffer member 150 may be made of different materials. In this case, it is preferable to increase the linear expansion coefficients of the connecting member 130, buffer member 150, and terminal 140 in that order. This can help prevent cracks in the terminal structure from a mechanical standpoint. Increasing the linear expansion coefficients in this order also includes cases where the linear expansion coefficients of the two members are equal.

Figure 3 is a partial cross-sectional view showing an enlarged view of the terminal structure of a modified example of the electrode-embedding member 100 according to the embodiment. As shown in Figure 3, the buffer member 150 preferably includes a first buffer member 151 arranged on the connecting member 130 side and a second buffer member 152 arranged on the terminal 140 side. In this case, it is preferable to increase the linear expansion coefficients of the connecting member 130, first buffer member 151, second buffer member 152, and terminal 140 in that order. This makes it possible to suppress cracks in the terminal structure from a mechanical standpoint.

Furthermore, when the buffer member 150 is configured to include a first buffer member 151 and a second buffer member 152, the connecting member 130 and the first buffer member 151 may be configured from the same material, and the linear expansion coefficients of the first buffer member 151, the second buffer member 152, and the terminal 140 may increase in that order.

The brazing material 160 secures the buffer member 150 and the terminal 140. The brazing material 160 electrically connects the connecting member 130, the terminal 140, or the buffer member 150 to each other.

The brazing material 160 is primarily composed of Au, with the surface layer containing 4 atoms% or more of Fe. This makes it easier for an oxide film of Fe to form on the surface of the brazing material 160 (at the boundary with the external environment) during use of the electrode-embedding member 100, or because the Fe selectively bonds with oxygen, oxidation of the connecting member 130 and buffer member 150 is suppressed. As a result, deterioration in the strength of the connecting member 130 and buffer member 150 is suppressed, and the strength of the terminal structure is maintained.

The brazing material 160 being primarily composed of Au means that the concentration of Au contained in the brazing material 160 is 80 wt% or more. Furthermore, the brazing material 160 containing 4 atoms% or more of Fe in the surface layer means that the concentration of metallic Fe contained in the brazing material 160 in the surface layer of the brazing material 160 after brazing (a region 20 μm or less from the surface of the brazing material 160) is 4 atoms% or more. This makes it easier for an oxide film of Fe to form on the surface of the brazing material 160 during use of the electrode-embedding member 100.

The Fe contained in the brazing material 160 may be added to the brazing material 160 before brazing. This makes it easier to include a predetermined amount of Fe in the brazing material 160. When adding Fe to the brazing material 160 before brazing, if the leaching of Fe from other components is not a consideration, it is preferable to add Fe to the brazing material 160 to achieve a predetermined concentration of, for example, 0.16 wt% or more and 10 wt% or less.

Furthermore, the Fe contained in the brazing material 160 may be dissolved from other components into the brazing material 160 during brazing, and then contained in the brazing material 160 after brazing. This is because even if the Fe is dissolved into the brazing material 160 during brazing, the formation of an oxide film on the Fe and selective bonding with oxygen will still occur during use of the electrode-embedded member 100.

When configuring the brazing material 160 so that Fe is eluted during brazing, the amount of Fe originally contained in or added to the brazing material 160 may be zero, and the entire amount of Fe contained in the brazing material 160 after brazing may be Fe eluted from other components. Alternatively, the brazing material 160 may be configured so that a smaller amount of Fe is contained or added than the target amount, with the shortfall being made up by Fe eluted from other components.

When the buffer member 150 is configured to leach Fe into the brazing material 160 during brazing, the other component that supplies Fe is preferably the buffer member 150. That is, the buffer member 150 preferably contains Fe. By including Fe in the buffer member 150, even if the brazing material 160 does not contain Fe, Fe is leached into the brazing material during brazing. As a result, the brazing material 160 after brazing contains Fe, which can be used as a raw material for oxide films, etc. In this case, to ensure that the brazing material 160 contains the desired amount of Fe after brazing, it is necessary to adjust the Fe concentration in the buffer member 150, the size of the buffer member 150, the area of contact with the brazing material 160, and other factors. When the buffer member 150 is configured to contain Fe, the buffer member 150 can be formed from, for example, W with Fe addition, Mo with Fe addition, or a Ni-containing alloy such as Kovar, Invar, Super Invar, or Niresist. This is because the Ni content facilitates the leaching of Fe into the brazing material.

When the buffer member 150 is configured to leach Fe into the brazing material 160 during brazing, and the buffer member 150 includes a first buffer member 151 and a second buffer member 152, it is preferable that the second buffer member be primarily Fe. By using a second buffer member primarily Fe, the brazing material 160 after brazing contains a sufficient amount of Fe, even if the brazing material does not contain Fe. Furthermore, when the brazing material 160 is configured to leach Fe into the brazing material during brazing, the concentration of Fe contained in the brazing material 160 after brazing will vary depending on the part. However, by using a material in which the second buffer member 152 located on the terminal 140 side is primarily Fe, the brazing material 160 will contain more Fe near its surface, making it more suitable as a raw material for oxide films, etc. If the second buffer member 152 is composed primarily of Fe, the second buffer member 152 can be formed from an alloy containing Ni, such as Kovar, Invar, Super Invar, or Niresist.

When the brazing material 160 is configured to leach Fe during brazing, the other component that supplies Fe may be a foil or other component (Fe supply component) that contains Fe or is primarily composed of Fe, and almost all of the Fe dissolves in the brazing material 160 during brazing. This allows the Fe concentration in the intended region of the brazing material 160 to be increased regardless of the buffer member 150, making it more suitable as a raw material for oxide films, etc. When an Fe supply component is used, it may be located anywhere. For example, it may be located at the position of the first buffer member 151 or the second buffer member 152. In other words, the Fe supply component may be located between the connecting member 130 and the buffer member 150, or between the buffer member 150 and the terminal 140. While other locations are possible, since the Fe supply component has a certain size, placing it in these locations facilitates manufacturing.

It is preferable that the brazing material 160 have an iron oxide film on its surface. This further suppresses oxidation of the connecting member 130 and the buffer member 150.

When measuring the intensity ratio of characteristic X-rays of O (oxygen) and Fe (iron) in EPMA or EDX analysis of a cross section perpendicular to the surface of the brazing material 160, it is preferable that the value at the surface of the brazing material 160 (ratio of characteristic X-ray spectra (O intensity/Fe intensity)) is at least twice the value at the interior of the brazing material 160. This further suppresses oxidation of the connecting member 130 and buffer member 150. The surface of the brazing material 160 refers to the region 20 μm or less from the surface of the brazing material 160, and the interior of the brazing material 160 refers to the region 100 μm or more away from the surface of the brazing material 160.

The electrode-embedding member 100 of the present invention is less susceptible to deterioration of the connecting member 130 and buffer member 150, and the strength of the terminal structure is less likely to decrease. As a result, the terminal 140 is less likely to fall off or cause poor electrical contact.

[Method of manufacturing electrode-embedded member]
Next, a method for manufacturing an electrode-embedded member according to this embodiment will be described. Figures 4 and 5 are flowcharts showing an example of a method for manufacturing an electrode-embedded member according to this embodiment. As shown in Figure 4, the method for manufacturing an electrode-embedded member according to this embodiment includes a preparation step S1, an arrangement step S2, and a brazing step S3.

More specifically, as shown in Figure 5, preparation step S1 comprises compact formation step T1, degreasing step T2, electrode preparation step T3, laminate formation step T4, firing step T5, and terminal hole processing step T6. The following describes a manufacturing method using a compact hot press method in which compacts are stacked, but since the Fe concentration in the brazing material after brazing step S3 is important in the present invention, each step may be replaced with a different method as long as it can adjust this concentration.

Figures 6(a)-(d) and 7(a)-(c) 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 of the present invention. Figures 6 and 7 show the manufacturing of the electrode-embedded member of Figure 1. First, we will explain the steps from the compact formation step T1 to the terminal hole processing step T6, which detail the preparation step S1.

In the compact formation step T1, multiple ceramic compacts 11 and 12 are formed from ceramic raw material powder. While the ceramic compact is divided into two components in FIG. 6 , it may be divided into three or more components depending on the design. For example, additives such as binders, plasticizers, and dispersants may be appropriately added to and mixed with the ceramic raw material powder to prepare a slurry. Granules (granulated powder) are then formed by spray drying or other methods, and the resulting mixture is then pressure-molded to form the multiple ceramic compacts 11 and 12. Various materials can be used as the ceramic raw material powder depending on the application of the electrode-embedded member. For example, AlN, Al ₂ O ₃ , Si ₃ N ₄ , SiC, etc. can be used. A sintering aid powder may be added to the ceramic raw material powder as needed.

The ceramic raw material powder is preferably highly pure, preferably 96% or higher, and more preferably 98% or higher. The average particle size of the ceramic raw material powder is preferably 0.1 μm or higher and 1.0 μm or lower.

The mixing method may be either wet or dry, and a mixer such as a ball mill or vibration mill may be used. Furthermore, known forming methods such as uniaxial pressing or cold isostatic pressing (CIP) may be used. The method of forming the ceramic compact is not limited to pressure forming; for example, green sheet lamination or slip casting can also be used. The ceramic compact can be manufactured by degreasing these as appropriate or by further calcining. A laminate may also be formed using a powder hot press method.

After forming, the multiple ceramic compacts 11, 12 may be machined to adjust the shape of the compacts. Furthermore, as shown in FIG. 6(b), one side of the ceramic compact 12 (the surface to be bonded to another ceramic compact 11) may have a recess formed in a shape that matches the shape of the electrode 120 and connecting member 130. The recess may be formed in the ceramic compact 11, or in both. Machining may be performed after degreasing.

In the debinding step T2, multiple ceramic molded bodies 11, 12 are debound at a predetermined temperature or higher for a predetermined time or longer to produce multiple ceramic debound bodies 21, 22. The ceramic molded bodies 11, 12 are heat-treated, for example, at a temperature of 400°C or higher and 800°C or lower to form ceramic debound bodies 21, 22. The debinding time is preferably 1 hour or higher and 120 hours or lower. An atmospheric or nitrogen atmosphere furnace can be used for debinding, but an atmospheric furnace is preferred to remove unnecessary components from the binder.

In the electrode preparation process step T3, electrodes 120 made of Mo, W, or the like and cut to a predetermined shape, and connecting members 130 made of Mo, W, or the like and processed to a predetermined shape are prepared.

In the laminate formation process step T4, the prepared electrodes 120, connecting members 130, and multiple ceramic degreased bodies 21, 22 are combined to form a flat laminate 30 shown in Figure 6(c) in which the electrodes 120 and connecting members 130 are embedded.

In the firing process step T5, the formed laminate 30 is uniaxially pressurized and fired in a direction perpendicular to the main surface (mounting surface) to obtain the fired body 40 shown in FIG. 6(d). The pressure applied is preferably 1 MPa or greater. The firing temperature and firing time vary depending on the type of ceramic used as the base material. For example, when the base is made of AlN, a temperature of 1500°C to 2000°C is preferred. The firing time is preferably 1 hour to 12 hours. The firing atmosphere is, for example, a nitrogen or inert gas atmosphere, but a vacuum atmosphere is also acceptable. As a result, the multiple ceramic degreased bodies 21 after heat treatment are sintered into a ceramic sintered body, which is then integrated to obtain the fired body 40 in which the electrodes 120 and connecting members 130 are embedded.

In the terminal hole processing step T6, the sintered body 40 is ground, polished, etc. to give it a predetermined outer shape, and the surface roughness of the mounting surface 112 is adjusted to a predetermined range, thereby producing the electrode embedding member precursor 50 shown in Figure 7(b). In addition, terminal holes 142 of a predetermined shape are drilled from the back side of the sintered body 40 to the terminal positions, reaching the connecting member 130.

A calcination step may be performed between the degreasing step T2 and the laminate formation step T4. When performing the calcination step, the degreased ceramic body is calcined to produce a calcined ceramic 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 and temperature vary depending on the type of ceramic used for the substrate. For example, when the substrate is made of AlN, calcination is preferably performed at a temperature of 1200°C to 1700°C for 0.5 to 12 hours. The calcination atmosphere is preferably a nitrogen or inert gas atmosphere, but a vacuum atmosphere or other atmosphere may also be used. When performing the calcination step, machining may be performed after the calcination step.

By following the steps shown in the above example, it is possible to prepare an electrode-embedding component precursor 50 comprising a flat substrate 110 made of a sintered ceramic body (preparation step S1), an electrode 120 embedded in the substrate 110, and a connecting member 130 electrically connected to the electrode 120 and embedded in the substrate 110, with a terminal hole 142 drilled through which at least a portion of one main surface of the connecting member 130 is exposed. Next, the placement step S2 and the brazing step S3 will be described.

In the placement process step S2, the buffer member 150 and the terminal 140 are prepared and placed in the terminal hole 142 of the electrode-embedding member precursor 50. The buffer member 150 to be placed may be thin, such as foil. Furthermore, foil may be placed in addition to the buffer member 150.

The prepared buffer member 150 may include a first buffer member 151 arranged on the connection member 130 side and a second buffer member 152 arranged on the terminal 140 side. The first buffer member 151 or second buffer member 152 may be thin, such as foil. Also, foil may be arranged in addition to the first buffer member 151 and second buffer member 152.

In the brazing process step S3, a brazing material 160 containing Au as its main component is prepared, and the buffer member 150 and terminal 140 placed in the terminal hole 142 are brazed and fixed using the brazing material 160, thereby producing the electrode-embedded member 100 shown in Figure 7(c).

In the manufacturing method of the present invention, the composition and size of the buffer member 150 prepared in the placement step S2 or the area in contact with the brazing material are adjusted, or the composition of the brazing material 160 prepared in the brazing step S3 is adjusted, so that the brazing material 160 after the brazing step S3 contains 4 atoms% or more of Fe in the surface layer. At this time, brazing may be performed by placing an Fe supplying member such as foil containing Fe or consisting primarily of Fe, which dissolves almost entirely in the brazing material 160 during brazing. When adjusting the Fe concentration contained in the buffer member 150, the size of the buffer member 150, the area in contact with the brazing material, etc., for example, a larger area in contact with the brazing material is preferable, and a thinner thickness is preferable. However, if the entire amount of Fe contained in the brazing material 160 after brazing is configured to be Fe eluted from the buffer member 150, if the buffer member 150 is too thin, much of it may dissolve in the brazing material, preventing the buffer member from functioning as a buffer member after brazing. Therefore, when configured in this manner, the thickness is preferably 0.2 mm or more and 2 mm or less. Furthermore, it is preferable that the corners of the ends of the main surface be chamfered, and that the chamfered corners be C0.5 mm or more. Furthermore, it is preferable that the buffer member 150 has high wettability with the brazing material 160, and it is more preferable that the surface be roughened to Ra 1 μm or more. When using an Fe supply member, if the thickness is too thin, the amount of eluted Fe may be insufficient. Therefore, it is preferable that the thickness of the Fe supply member be 0.05 mm or more and less than 2 mm.

By doing this, it is possible to manufacture an electrode-embedding member 100 that is less likely to deteriorate during use in the actual process, that is less likely to reduce the strength of the terminal structure, and that is less likely to cause the terminal 140 to fall off or to have poor electrical contact.

[Examples and Comparative Examples]
Example 1
A ceramic raw material powder primarily composed of AlN _with 5 wt% _Y2O3 was subjected to CIP molding (pressure 1 ton/ ^cm2 ) to obtain a green body ingot. This was then machined to form a ceramic green body with a diameter of 340 mm and a thickness of 20 mm, and another ceramic green body with a diameter of 340 mm and a thickness of 10 mm. A recess with a diameter of 300 mm and a depth of 0.1 mm was provided on one side of the 20 mm green body, sharing the center of the green body, for accommodating an electrode. Furthermore, a recess with a diameter of 8.5 mm and a depth of 0.25 mm was provided at a predetermined position where a terminal would be formed to accommodate a connecting member.

Next, the ceramic compact was degreased at 550°C for 12 hours to produce a ceramic degreased body. Next, a 294mm diameter molybdenum mesh (wire diameter 0.1mm, plain weave, mesh size #50) was cut to the specified shape to prepare electrodes. Additionally, two connecting members measuring φ8mm x 0.2mm were produced from W pellets. Next, the connecting members and electrodes were placed in the recesses of a ceramic degreased body with a recess, and sandwiched between the other ceramic degreased body to produce an electrode-embedded member precursor.

Next, the electrode-embedding member precursor was placed in a hot press furnace and heat-treated from 800°C to 1500°C for 14 hours. Next, a force of 10 MPa was applied in a direction perpendicular to the main surface (mounting surface) of the electrode-embedding member precursor, and it was uniaxially hot-press fired at 1800°C for 2 hours. In this way, the substrate with the electrodes and connecting members embedded was fired.

The entire surface was then ground and polished to form a wafer-mounting surface with a total thickness of 20 mm, an insulating layer thickness of 1.0 mm, and a surface roughness of Ra 0.4 μm. Flat-bottom holes with a diameter of φ5.5 mm were drilled from the back side of the ceramic base to the terminal positions, reaching the connecting members.

Next, Fe was added to the BAu-4 brazing filler metal to prepare an Au-Ni brazing filler metal containing 1 wt% Fe. A 5 mm diameter, 2 mm thick W buffer member and a 5 mm diameter, 50 mm long cylindrical Ni power supply terminal were attached to the exposed bottom surface of the connecting member via the prepared Au-Ni brazing filler metal. Brazing was then performed in a vacuum furnace at 1050°C using the Au-Ni brazing filler metal to complete the embedded electrode member. In this way, the embedded electrode member of Example 1 was produced.

Example 2
In Example 2, instead of the W buffer member used in Example 1, a first W buffer member with a diameter of 5 mm and a thickness of 2 mm and a second Kovar buffer member with a diameter of 5 mm and a thickness of 2 mm were used. The corners of the end of the main surface on the terminal side of the second buffer member were processed to C0.5 mm to increase the area in contact with the brazing material, and the surface was roughened to Ra 4 μm to improve the wettability of the buffer member with the brazing material. Furthermore, instead of the Au—Ni-based brazing material containing 1 wt % Fe, a BAu-4 brazing material with no added Fe was used. Otherwise, the electrode-embedded member of Example 2 was produced under the same conditions as Example 1.

Example 3
In Example 3, instead of the W buffer member used in Example 1, a W buffer member with a diameter of 5 mm and a thickness of 2 mm containing 1 wt % Fe was used. The buffer member was processed in the same manner as the second buffer member of Example 2. In addition, instead of the Au-Ni based brazing material containing 1 wt % Fe, a BAu-4 brazing material with no added Fe was used. Except for this, the electrode-embedded member of Example 3 was produced under the same conditions as Example 1.

Example 4
In Example 4, instead of the W buffer member used in Example 1, a first buffer member made of W with a diameter of 5 mm and a thickness of 2 mm and containing 1 wt % Fe, and a second buffer member made of Kovar with a diameter of 5 mm and a thickness of 2 mm, were used. The second buffer member was processed in the same manner as in Example 2. In addition, instead of the Au-Ni-based brazing material containing 1 wt % Fe, a BAu-4 brazing material with no added Fe was used. The electrode-embedded member of Example 4 was fabricated under the same conditions as in Example 1 except for the above.

Example 5
In Example 5, instead of the W buffer member used in Example 1, a first buffer member made of Mo with a diameter of 5 mm and a thickness of 2 mm and a second buffer member made of Kovar with a diameter of 5 mm and a thickness of 2 mm were used. The second buffer member was processed in the same manner as in Example 2. In addition, instead of the Au-Ni based brazing material containing 1 wt% Fe, a BAu-4 brazing material with no added Fe was used. The electrode-embedded member of Example 5 was fabricated under the same conditions as in Example 1 except for the above.

Example 6
In Example 6, instead of the W connecting member used in Example 1, a Mo connecting member was embedded and fired. Furthermore, instead of the W buffer member used in Example 1, a first Mo buffer member with a diameter of 5 mm and a thickness of 2 mm and a second Kovar buffer member with a diameter of 5 mm and a thickness of 2 mm were used. The second buffer member was processed in the same manner as in Example 2. Furthermore, instead of the Au—Ni-based brazing material containing 1 wt % Fe, a BAu-4 brazing material with no added Fe was used. The electrode-embedded member of Example 6 was fabricated under the same conditions as in Example 1, except for the above.

Example 7
In Example 7, instead of the W buffer member used in Example 1, a Kovar foil with a diameter of 5 mm and a thickness of 0.1 mm was placed as the first buffer member, and a W buffer member with a diameter of 5 mm and a thickness of 2 mm was placed as the second buffer member, and brazing was performed. Also, instead of the Au-Ni-based brazing material containing 1 wt % Fe, a BAu-4 brazing material with no added Fe was used. Otherwise, the electrode-embedded member of Example 7 was produced under the same conditions as Example 1.

(Example 8)
In Example 8, a buffer member made of Ni-resist was placed in place of the W buffer member used in Example 1, and brazing was performed. The buffer member was processed in the same manner as the second buffer member in Example 2. In addition, a BAu-4 brazing material with no added Fe was used instead of the Au-Ni brazing material containing 1 wt % Fe. The electrode-embedded member of Example 8 was produced under the same conditions as Example 1 except for the above.

(Comparative Example 1)
In Comparative Example 1, a BAu-4 brazing filler metal with no added Fe was used instead of the Au—Ni brazing filler metal containing 1 wt % Fe used in Example 1. Except for this, the electrode-embedded member of Comparative Example 1 was produced under the same conditions as in Example 1.

(Comparative Example 2)
In Comparative Example 2, a Kovar foil with a diameter of 5 mm and a thickness of 0.03 mm was placed between the W buffer member and the terminal used in Example 1, and brazing was performed. Also, instead of the Au-Ni brazing material containing 1 wt % Fe, a BAu-4 brazing material with no added Fe was used. Otherwise, the electrode-embedded member of Comparative Example 2 was produced under the same conditions as in Example 1.

[Performance evaluation]
(Temperature cycle test)
The terminals were connected to an external power source, and power was applied, heating the surface temperature of the mounting surface of the electrode-embedded member to 650° C., maintaining this temperature for 2 hours, and then cooling to 200° C. This cycle was repeated 20 times. The temperature cycle test was carried out in an environment exposed to the atmosphere.

(Tensile strength test)
After the temperature cycle test, the base of the electrode-embedded member was fixed to a strength tester, and the terminal was pulled vertically to measure the strength at which it broke.

(Composition analysis of brazing filler material)
The electrode-embedded member was cut along 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 connecting member, electrode, buffer member, and brazing material were exposed and polished, after which the composition of the brazing material was analyzed using EPMA. Specifically, the cross section was magnified 1000 times using the EPMA device, and elemental mapping of the cross section was performed. The elements detected were Fe and O. Note that the composition analysis of the brazing material can also be performed using an EDX-SEM device.

The degree of Fe oxidation was also evaluated by measuring (O intensity/Fe intensity) from the characteristic X-ray spectrum measured at the analysis point. The area evaluated was an approximately 20 μm square area within a specified range (100 μm to 120 μm) of the brazing material surface (area 20 μm or less from the surface) and the interior of the brazing material (area 100 μm or more from the surface).

(Measurement of the thickness of the Fe oxide on the surface)
After the temperature cycle test, the cross section of the brazing material was observed under an SEM (1000x magnification) to measure the thickness of the oxide on the surface. Five points per field of view were measured, and the average value was taken as the thickness. When the thickness was 1 μm or more, it was judged that Fe oxide had formed, and when it was less than 1 μm or when it was difficult to measure, it was judged that there was no oxide on the surface.

Figure 8 is a table showing the manufacturing conditions and measurement results for the examples and comparative examples. It was confirmed that examples 1 to 8 maintained high terminal strength after the thermal cycle test compared to comparative examples 1 and 2.

In the composition analysis of the surface layer of the brazing filler metal in Examples 1 to 8, Fe was found to be 4 atoms% or more. In contrast, Comparative Example 1 was found to be below the detection limit and therefore could be considered to contain no Fe. Furthermore, Comparative Example 2 had an Fe content of 3.5 atoms%, which did not meet the standard. In cross-sectional observation, the Kovar foil in both Example 7 and Comparative Example 2 was almost completely melted. On the other hand, the Fe content in the surface layer of the brazing filler metal in Comparative Example 2 did not meet the standard. This is thought to be because the Kovar foil in Comparative Example 2 was too thin. It is presumed that the connection or buffer material in Comparative Examples 1 and 2 deteriorated during the thermal cycle test due to the lack of Fe or the low Fe content in the brazing filler metal, resulting in weakened terminal strength. Furthermore, in Examples 1 to 8, an Fe oxide film was observed on the surface of the brazing filler metal after the thermal cycle.

Furthermore, the ratio of characteristic X-ray spectra (O intensity/Fe intensity) in the surface layer of the brazing filler metals in Examples 1 to 8 was greater than the value inside the brazing filler metal, with the difference being more than twice the value inside. Furthermore, in Comparative Example 2, the value was 1.4 times higher. This also confirmed that an Fe oxide film was formed on the surface of the brazing filler metal in the examples after the thermal cycle.

These results confirm that the electrode-embedding member of the present invention is less susceptible to deterioration of the connecting members and buffering members, and less likely to reduce the strength of the terminal structure, making it less likely for the terminal to fall off or for poor electrical contact to occur. It was also confirmed that the manufacturing method of the present invention can be used to manufacture such an electrode-embedding member.

The present invention is not limited to the above-described embodiments, and naturally includes 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.

11, 12 Ceramic formed bodies 21, 22 Ceramic degreased body 30 Laminate 40 Sintered body 50 Electrode-embedding member precursor 100 Electrode-embedding member 110 Base 112 Mounting surface 120 Electrode 130 Connecting member 140 Terminal 142 Terminal hole 150 Cushioning member 151 First cushioning member 152 Second cushioning member 160 Brazing material

Claims (5)

An electrode-embedding member,
a flat substrate made of a ceramic sintered body;
an electrode embedded in the substrate;
a connecting member electrically connected to the electrode and embedded in the substrate;
a terminal for supplying electricity to the electrode;
a buffer member disposed between the connection member and the terminal;
a brazing material for fixing the buffer member and the terminal,
The brazing material contains Au as a main component and contains 4 atoms% or more of Fe in a surface layer that is a region of 20 μm or less from the surface of the brazing material ,
An electrode-embedding member, characterized in that an oxide of Fe is formed on the surface of the brazing material . 2. The electrode-embedding member according to claim 1, wherein the strength ratio of characteristic X-rays of O and Fe in the surface layer of the brazing material is at least twice the strength ratio in the interior of the brazing material as determined by EPMA analysis or EDX analysis of a cross section perpendicular to the surface of the brazing material. 3. The electrode-embedding member according to claim 1, wherein the buffer member contains Fe. the buffer member includes a first buffer member disposed on the connection member side and a second buffer member disposed on the terminal side,
4. The electrode-embedding member according to claim 1, wherein the second buffer member is mainly composed of Fe. A method for manufacturing an electrode-embedded member,
a preparation step of preparing an electrode-embedding member precursor, the electrode-embedding member precursor comprising a flat-plate-shaped substrate made of a ceramic sintered body, an electrode embedded in the substrate, and a connection member electrically connected to the electrode and embedded in the substrate, the electrode-embedding member precursor having a terminal hole formed therein through which at least a portion of one main surface of the connection member is exposed;
an arrangement step of preparing a buffer member and a terminal, and arranging the buffer member and the terminal in the terminal hole of the electrode-embedding member precursor;
a brazing step of preparing a brazing material containing Au as a main component, and brazing and fixing the buffer member and the terminal disposed in the terminal hole using the brazing material,
the components and size of the buffer member prepared in the disposing step or the area in contact with the brazing material are adjusted, or the components of the brazing material prepared in the brazing step are adjusted, so that the brazing material after the brazing step contains 4 atoms% or more of Fe in a surface layer that is a region of 20 μm or less from the surface of the brazing material;
The method for manufacturing an electrode-embedded member, comprising heating the brazing material after the brazing step to form an oxide of Fe on the surface of the brazing material.