Ceramic structure

Abstract

This ceramic structure comprises a body part, a wiring layer, and a via conductor. The body part is made from ceramic. The wiring layer is positioned along a first surface of the body part inside the body part. The via conductor is electrically and mechanically connected to the wiring layer and extends in a direction intersecting the first surface. The wiring layer and the via conductor each include a plurality of inorganic particles and a conductor mainly composed from the same metal. When inorganic particles included in the wiring layer are defined as first inorganic particles, the average equivalent circle diameter and area occupancy rate of the first inorganic particles in a cross-sectional view are defined as a first equivalent circle diameter and first area occupancy rate, respectively, the inorganic particles included in the via conductor are defined as second inorganic particles, and the average equivalent circle diameter and area occupancy rate of the second inorganic particles in a cross-sectional view are defined as a second equivalent circle diameter and second area occupancy rate, respectively, the first equivalent circle diameter is smaller than the second equivalent circle diameter, and the first area occupancy rate is smaller than the second area occupancy rate.

Description

Ceramic structures

[0001] The embodiments of the disclosure relate to ceramic structures.

[0002] In the process of manufacturing semiconductor components, sample holders are used to hold samples such as semiconductor wafers that are to be processed in various ways. As a ceramic structure that constitutes such a sample holder, for example, a ceramic structure is known that comprises a main body made of ceramic, a wiring layer located inside the main body, and, for example, cylindrical via conductors. The wiring layer is located along the main surface of the main body, and the via conductors extend in a direction intersecting the main surface.

[0003] Furthermore, in order to reduce the difference in thermal expansion coefficient with the main body which is made of ceramic, the wiring layer and via conductors have multiple inorganic particles in addition to conductive components.

[0004] Japanese Patent Publication No. 2016-225557

[0005] The ceramic structure of this disclosure comprises a main body, a wiring layer, and a via conductor. The main body is made of ceramic. The wiring layer is located inside the main body along a first surface of the main body. The via conductor is electrically and mechanically connected to the wiring layer and extends in a direction intersecting the first surface. The wiring layer and the via conductor each contain a plurality of inorganic particles and a conductor whose main component is the same metal. If the inorganic particles contained in the wiring layer are designated as first inorganic particles, and the average equivalent circle diameter and area occupancy of the first inorganic particles in a cross-sectional view are designated as the first equivalent circle diameter and the first area occupancy, respectively, and the inorganic particles contained in the via conductor are designated as second inorganic particles, and the average equivalent circle diameter and area occupancy of the second inorganic particles in a cross-sectional view are designated as the second equivalent circle diameter and the second area occupancy, respectively, then the first equivalent circle diameter is smaller than the second equivalent circle diameter, and the first area occupancy is smaller than the second area occupancy.

[0006] Figure 1 is a cross-sectional view showing an example of the configuration of a ceramic structure according to the embodiment. Figure 2 is a cross-sectional SEM image of a wiring layer and a via conductor according to the embodiment. Figure 3 is a diagram showing an example of the distribution of first inorganic particles in the wiring layer according to the embodiment. Figure 4 is a diagram showing an example of the distribution of second inorganic particles in the via conductor according to the embodiment. Figure 5 is a cross-sectional view showing an example of the configuration of a ceramic structure according to another embodiment 1. Figure 6 is a cross-sectional view showing an example of the configuration of a ceramic structure according to another embodiment 2.

[0007] Hereinafter, embodiments of the ceramic structure disclosed in this application will be described with reference to the attached drawings. However, this disclosure is not limited to the embodiments shown below. Furthermore, the embodiments can be combined as appropriate, provided that the processing details are not inconsistent. Also, the same parts are denoted by the same reference numerals in the following embodiments, and redundant descriptions are omitted.

[0008] Furthermore, in the embodiments described below, expressions such as "parallel" or "perpendicular" may be used, but these expressions do not require strict parallelism or perpendicularity. In other words, each of the above expressions allows for deviations such as manufacturing accuracy and installation accuracy.

[0009] Furthermore, in the drawings referenced below, for the sake of clarity, mutually orthogonal X, Y, and Z axis directions are sometimes defined, and a Cartesian coordinate system is shown in which the Z axis direction is the thickness direction of the main body of the ceramic structure.

[0010] In the process of manufacturing semiconductor components, sample holders are used to hold samples such as semiconductor wafers that are to be processed in various ways. As a ceramic structure that constitutes such a sample holder, for example, a ceramic structure is known that comprises a main body made of ceramic, a wiring layer located inside the main body, and, for example, cylindrical via conductors. The wiring layer is located along the main surface of the main body, and the via conductors extend in a direction intersecting the main surface.

[0011] Furthermore, in order to reduce the difference in thermal expansion coefficient with the main body which is made of ceramic, the wiring layer and via conductors have multiple inorganic particles in addition to conductive components.

[0012] On the other hand, in the conventional technology described above, the thickness of the wiring layer is small compared to the thickness of the via conductor, so the influence of inorganic particles on the conductive paths within the wiring layer is greater than that of the via conductor. As a result, there was a risk that the variation in electrical resistance due to the distribution of inorganic particles in the wiring layer would become large.

[0013] Therefore, there is a need for a technology that can solve the above problems and reduce variations in electrical resistance in the wiring layer of ceramic structures.

[0014] First, the configuration of the ceramic structure 1 according to the embodiment will be described with reference to Figures 1 to 4. Figure 1 is a cross-sectional view showing an example of the configuration of the ceramic structure 1 according to the embodiment. As shown in Figure 1, the ceramic structure 1 according to the embodiment may include a main body portion 10, a wiring layer 20, and a via conductor 30.

[0015] The main body 10 may be made of ceramic. The main body 10 may be formed from a ceramic-containing raw material into a flat plate shape, for example, a roughly circular disc shape. The main body 10 may be made of, for example, aluminum oxide (Al ２ O ３ ), aluminum nitride (AlN), or yttrium oxide (Y ２ O ３ ) may also contain as a main component.

[0016] The main body 10 may have, for example, a first surface 10a which is the main surface and a second surface 10b which is the back surface. The first surface 10a may be, for example, the surface that holds the sample when the ceramic structure 1 is used as a sample holder. The second surface 10b may be located on the opposite side from the first surface 10a.

[0017] The wiring layer 20 may be located inside the main body 10. The wiring layer 20 may be located along the first surface 10a of the main body 10, for example, parallel to the first surface 10a. For example, in the example shown in Figure 1, two wiring layers 20 are located inside the main body 10.

[0018] In this disclosure, the wiring layer 20 is not limited to being located inside the main body 10; for example, it may be partially or entirely exposed from the main body 10.

[0019] Figure 2 is a cross-sectional SEM image of the wiring layer 20 and via conductor 30 according to the embodiment, and is a cross-sectional SEM image of region A shown in Figure 1. Note that the cross-sectional SEM image in Figure 2 was taken with the main body 10 removed. In other words, the main body 10 is not visible in the cross-sectional SEM image in Figure 2. As shown in Figure 2, the wiring layer 20 may have, for example, a plurality of first inorganic particles 20a and a first conductor 20b.

[0020] The plurality of first inorganic particles 20a may be composed mainly of inorganic materials such as aluminum oxide, aluminum nitride, or yttrium oxide. The first conductor 20b may be composed mainly of metals such as platinum (Pt), molybdenum (Mo), or tungsten (W).

[0021] Thus, by having a plurality of first inorganic particles 20a in addition to the first conductor 20b in the wiring layer 20, the difference in thermal expansion coefficient between the ceramic body portion 10 and the metal-containing wiring layer 20 can be reduced. Therefore, according to this embodiment, the peeling of the wiring layer 20 from the body portion 10 can be reduced.

[0022] Returning to the explanation of Figure 1, the via conductor 30 may be electrically and mechanically connected to the wiring layer 20, for example. The via conductor 30 may extend in a direction intersecting the first surface 10a of the main body 10, for example, in a direction perpendicular to the first surface 10a. For example, in the example of Figure 1, two via conductors 30 are positioned to electrically connect two stacked wiring layers 20.

[0023] As shown in Figure 2, the via conductor 30 may have, for example, a plurality of second inorganic particles 30a and a second conductor 30b. The plurality of second inorganic particles 30a may be mainly composed of an inorganic material such as aluminum oxide, aluminum nitride, or yttrium oxide.

[0024] The second conductor 30b may be composed mainly of a metal such as platinum, molybdenum, or tungsten.

[0025] Thus, by having a plurality of second inorganic particles 30a in addition to the second conductor 30b in the via conductor 30, the difference in thermal expansion coefficient between the ceramic body portion 10 and the metal-containing via conductor 30 can be reduced. Therefore, according to this embodiment, the peeling of the via conductor 30 from the body portion 10 can be reduced.

[0026] In this embodiment, the average equivalent diameter of the first inorganic particle 20a in cross-sectional view is defined as the first equivalent diameter, and the area occupancy rate of the first inorganic particle 20a in cross-sectional view is defined as the first area occupancy rate. Similarly, in this embodiment, the average equivalent diameter of the second inorganic particle 30a in cross-sectional view is defined as the second equivalent diameter, and the area occupancy rate of the second inorganic particle 30a in cross-sectional view is defined as the second area occupancy rate.

[0027] In this disclosure, "equivalent circular diameter of inorganic particles" refers to the diameter of a circle having the same area as the projected area of ​​the inorganic particles in question, i.e., the projected area equivalent circular diameter. Furthermore, in this disclosure, "area occupancy rate of inorganic particles" refers to the ratio of the area occupied by inorganic particles to the total area of ​​a single unit area.

[0028] Furthermore, in this embodiment, the first equivalent diameter may be smaller than the second equivalent diameter, and the first area occupancy rate may be smaller than the second area occupancy rate.

[0029] Figure 3 shows an example of the distribution of first inorganic particles 20a in the wiring layer 20 according to the embodiment. Figure 4 shows an example of the distribution of second inorganic particles 30a in the via conductor 30 according to the embodiment.

[0030] For example, in the example shown in Figure 3, which is an enlarged view of the wiring layer 20, the first equivalent diameter was 0.58 μm, and the first area occupancy rate was 7.2 area%. Also, in the example shown in Figure 4, which is an enlarged view of the via conductor 30, the second equivalent diameter was 5.58 μm, and the second area occupancy rate was 24.3 area%.

[0031] Thus, in this embodiment, the average equivalent circle diameter and area occupancy rate of the first inorganic particles 20a in the wiring layer 20 may be smaller than the average equivalent circle diameter and area occupancy rate of the second inorganic particles 30a in the via conductor 30. This makes it possible to reduce the influence of the first inorganic particles 20a on the conductive paths within the wiring layer 20, even when the wiring layer 20 is thin.

[0032] Therefore, according to this embodiment, even when the wiring layer 20 is made thinner, variations in electrical resistance in the wiring layer 20 can be reduced.

[0033] Furthermore, in this embodiment, the wiring layer 20 can be made thinner while suppressing variations in electrical resistance, thereby reducing the internal stress of the wiring layer 20. Therefore, according to this embodiment, the peeling of the wiring layer 20 from the main body 10 can be reduced.

[0034] In this disclosure, it is not necessary for the first equivalent diameter to be smaller than the second equivalent diameter and the first area occupancy rate to be smaller than the second area occupancy rate in all regions of the wiring layer 20 and via conductor 30 in the ceramic structure 1.

[0035] For example, in this disclosure, in some areas of the wiring layer 20 and via conductor 30, the first equivalent diameter is smaller than the second equivalent diameter, and the first area occupancy is smaller than the second area occupancy. Even in this case, variations in electrical resistance in the wiring layer 20 can be reduced in the relevant areas.

[0036] Furthermore, in this embodiment, the first conductor 20b of the wiring layer 20 and the second conductor 30b of the via conductor 30 may be primarily composed of the same metal. This allows for good bonding at the interface between the wiring layer 20 and the via conductor 30. Therefore, according to this embodiment, the reliability of the ceramic structure 1 is improved.

[0037] Furthermore, this disclosure is not limited to cases where the first conductor 20b and the second conductor 30b are primarily composed of the same metal, but may be primarily composed of different metals.

[0038] Also, in the embodiment, the first inorganic particles 20a of the wiring layer 20 and the second inorganic particles 30a of the via conductor 30 may have the same inorganic material as the main component. Thereby, good bonding can be obtained at the interface between the wiring layer 20 and the via conductor 30. Therefore, according to the embodiment, the reliability of the ceramic structure 1 is improved.

[0039] Also, in the embodiment, the first inorganic particles 20a of the wiring layer 20, the second inorganic particles 30a of the via conductor 30, and the main body portion 10 may all have the same inorganic material as the main component. Thereby, good bonding can be obtained at the interfaces of the wiring layer 20, the via conductor 30, and the main body portion 10. Therefore, according to the embodiment, the reliability of the ceramic structure 1 is improved.

[0040] Note that in the present disclosure, it is not limited to the case where the first inorganic particles 20a, the second inorganic particles 30a, and the main body portion 10 all have the same inorganic material as the main component, and at least one part may have a different inorganic material as the main component from other parts.

[0041] Also, in the embodiment, in a cross-sectional view, the number of the first inorganic particles 20a per unit area may be larger than the number of the second inorganic particles 30a per unit area. In the present disclosure, the "number of inorganic particles" refers to the number of inorganic particles observed in the entire area of one unit area. The specific unit area may be an area where 5 or more first inorganic particles 20a and second inorganic particles 30a can be observed respectively in a cross-sectional view.

[0042] For example, in the example of FIG. 3 in which the wiring layer 20 is enlarged, the number of the first inorganic particles 20a was 9. Also, in the example of FIG. 4 in which the via conductor 30 is enlarged, the number of the second inorganic particles 30a was 63. It is better to compare these on a per unit area basis. The observation range of the first inorganic particles 20a is 33.4 μm ２ and the observation range of the second inorganic particles 30a is 6.362 μm ２ is.

[0043] Therefore, when comparing the same area, the number of the first inorganic particles 20a is 1.714 particles / 6.362 μm ２ and the number of the second inorganic particles 30a is 63 particles / 6.362 μm ２is obtained. In addition, inorganic particles with an area smaller than 0.1 μm ２ were not targeted.

[0044] Thus, by increasing the number of the first inorganic particles 20a contained in the wiring layer 20, even when the average equivalent circle diameter and the area occupancy rate of the first inorganic particles 20a are reduced, the difference in the coefficient of thermal expansion between the main body portion 10 made of ceramic and the wiring layer 20 containing metal can be reduced. Therefore, according to the embodiment, peeling of the wiring layer 20 from the main body portion 10 can be reduced.

[0045] Further, in the present disclosure, if the ceramic structure 1 is used as an electrostatic chuck, the wiring layer 20 may be used as an electrostatic adsorption electrode. Further, if the ceramic structure 1 is used as a heater, the wiring layer 20 may be used as a resistance heating electrode. Further, if the ceramic structure 1 is used as a support for a plasma device, the wiring layer 20 may be used as an electrode for plasma generation.

[0046] The ceramic structure 1 according to the embodiment can be manufactured, for example, by the following steps.

[0047] First, a ceramic green sheet that will be the main body portion 10 is manufactured. Specifically, a ceramic powder such as aluminum oxide, a binder, and a solvent are mixed to produce a ceramic slurry.

[0048] Then, a ceramic green sheet is manufactured by using a tape casting method such as a doctor blade method, a roll compaction method, or a calendar roll method from this ceramic slurry.

[0049] Further, a conductive paste that will be the wiring layer 20 may be manufactured by mixing a metal powder such as platinum, a ceramic powder such as aluminum oxide, a binder, and a solvent. In the embodiment, for example, the particle size of the metal powder that is the raw material of the wiring layer 20 is in the nano size to several μm, and the particle size of the ceramic powder is in the nano size.

[0050] Similarly, another conductive paste that becomes the via conductor 30 may be prepared by mixing metal powder such as platinum, ceramic powder such as aluminum oxide, a binder, and a solvent. In this embodiment, for example, the particle size of the metal powder that is the raw material for the via conductor 30 is several μm to several tens of μm, and the particle size of the ceramic powder is several μm.

[0051] In this way, by controlling the particle sizes of the raw materials, the metal powder and ceramic powder, the electrical resistance of the conductive paste that forms the wiring layer 20 becomes lower than the electrical resistance of the conductive paste that forms the via conductor 30.

[0052] Next, holes are formed in the ceramic green sheet using a laser, drill, or punching, and conductive paste, which will become via conductors 30, is filled into the holes. Then, conductive paste, which will become the wiring layer 20, is applied to the surface of the ceramic green sheet using a printing method such as screen printing.

[0053] Next, multiple ceramic green sheets, each containing a conductive paste that will form the wiring layer 20 and via conductors 30, are stacked to create a raw laminate. Then, after a binder removal treatment is performed at a predetermined temperature, the laminate is fired at another predetermined temperature to produce a fired body.

[0054] Next, the fired body is ground using a surface grinder, machining center, etc., to obtain a predetermined shape, and then cleaning and shipping inspection are performed to complete the ceramic structure 1 according to the embodiment.

[0055] Furthermore, the first equivalent circle diameter and first area occupancy rate of the wiring layer 20 in the ceramic structure 1, and the second equivalent circle diameter and second area occupancy rate of the via conductor 30 can be calculated, for example, by the following process.

[0056] First, the ceramic structure 1 is cut, and the cut surface is ground, polished, etc. using a predetermined method to obtain an observation surface of the ceramic structure 1. Then, this observation surface is observed with a scanning electron microscope (SEM) at a magnification of approximately 500 to 5000 times, and surface analysis of the observation surface is performed using an electron beam microanalyzer (EPMA).

[0057] Next, through this surface analysis mapping, the areas in the wiring layer 20 and via conductor 30 where the presence of elements contained in the ceramic powder, such as aluminum, is confirmed are considered to be the first inorganic particles 20a and the second inorganic particles 30a, respectively.

[0058] Similarly, by mapping this surface analysis, the areas in the wiring layer 20 and via conductor 30 where the presence of elements contained in the metal powder, such as platinum, is confirmed are considered to be the first conductor 20b and the second conductor 30b, respectively.

[0059] Then, image analysis is performed on the image data obtained by capturing the observation surface using SEM and EPMA, by applying the image analysis software Image Pro ver.10 (hereinafter referred to as Image Pro) manufactured by MEDIA CYBERNETICS. This makes it possible to determine the average equivalent circle diameter and area occupancy rate of the first inorganic particle 20a and the second inorganic particle 30a.

[0060] First, the EPMA observation data is imported into Image Pro. Next, the size is calibrated using the scale bar that indicates the reference length shown in the observation data. After that, the image is binarized. Binarization is performed by adjusting the contrast so that the particle sizes of the first inorganic particle 20a and the second inorganic particle 30a observed with SEM and EPMA are the same.

[0061] After determining the observation range, the area of ​​each particle of the first inorganic particle 20a and the second inorganic particle 30a shown within the observation range is measured. The equivalent circular diameter is then calculated from these area measurements. By calculating the average value of the equivalent circular diameters based on these values, the first equivalent circular diameter and first area occupancy rate of the first inorganic particle 20a in the wiring layer 20, and the second equivalent circular diameter and second area occupancy rate of the second inorganic particle 30a in the via conductor 30 are calculated.

[0062] Image Pro was also used to count the number of first inorganic particles 20a and second inorganic particles 30a. The quantity measured by area as described above was used as the number of particles. Area measurement was performed using a 0.1 μm scale. ２The following first inorganic particles 20a and second inorganic particles 30a were not counted. Note that Image Pro was used as the image analysis software here, but other image analysis software may be used.

[0063] Note that the cross-sectional shape of the ceramic structure 1 according to the embodiment is not limited to the example in Figure 1. Figure 5 is a cross-sectional view showing an example of the configuration of the ceramic structure 1 according to another embodiment 1. As shown in Figure 5, in the other embodiment 1, the configuration of the main body 10 and the wiring layer 20 differs from that of the embodiment described above.

[0064] Specifically, in another embodiment 1, a recess 10c may be provided on the second surface 10b of the main body 10. Furthermore, in another embodiment 1, the wiring layer 20 on the second surface 10b side may be omitted, and the lower end of the via conductor 30 may be exposed at the bottom surface 10d of the recess 10c.

[0065] Even with this cross-sectional shape, by making the average equivalent circle diameter and area occupancy rate of the first inorganic particles 20a (see Figure 2) in the wiring layer 20 smaller than the average equivalent circle diameter and area occupancy rate of the second inorganic particles 30a (see Figure 2) in the via conductor 30, variations in electrical resistance in the wiring layer 20 can be reduced.

[0066] Figure 6 is a cross-sectional view showing an example of the configuration of the ceramic structure 1 according to another embodiment 2. As shown in Figure 6, in another embodiment 2, in addition to the configuration of another embodiment 1 described above, external wiring 40 may be provided on the bottom surface 10d of the recess 10c. This external wiring 40 may be electrically and mechanically connected to the via conductor 30 exposed on the bottom surface 10d.

[0067] Even with this cross-sectional shape, by making the average equivalent circle diameter and area occupancy rate of the first inorganic particles 20a (see Figure 2) in the wiring layer 20 smaller than the average equivalent circle diameter and area occupancy rate of the second inorganic particles 30a (see Figure 2) in the via conductor 30, variations in electrical resistance in the wiring layer 20 can be reduced.

[0068] Although the embodiments of this disclosure have been described above, this disclosure is not limited to the embodiments described above, and various modifications are possible as long as they do not deviate from the spirit of the disclosure.

[0069] For example, in the above embodiment, it was shown that the ceramic structure 1 is applicable to a sample holder, but the members to which the ceramic structure 1 of this disclosure is applicable are not limited to sample holders. For example, the ceramic structure 1 of this disclosure may be applied to a wiring board for mounting optical elements and electronic elements, or to antenna elements such as array antennas.

[0070] This also reduces variations in electrical resistance in the wiring layer 20 by making the average equivalent circle diameter and area occupancy rate of the first inorganic particles 20a in the wiring layer 20 smaller than the average equivalent circle diameter and area occupancy rate of the second inorganic particles 30a in the via conductor 30.

[0071] Further effects and other embodiments can be readily derived by those skilled in the art. Therefore, broader embodiments of this disclosure are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the spirit or scope of the overall concept of the invention as defined by the appended claims and their equivalents.

[0072] Furthermore, this technology can also take the following configuration: (1) A ceramic structure comprising: a main body made of ceramic; a wiring layer located inside the main body along a first surface of the main body; and via conductors electrically and mechanically connected to the wiring layer and extending in a direction intersecting the first surface, wherein the wiring layer and the via conductor each contain a plurality of inorganic particles and a conductor mainly composed of the same metal, and the inorganic particles contained in the wiring layer are designated as first inorganic particles, and the average equivalent circle diameter and area occupancy rate of the first inorganic particles in a cross-sectional view are designated as the first equivalent circle diameter and the first area occupancy rate, respectively, and the inorganic particles contained in the via conductor are designated as second inorganic particles, and the average equivalent circle diameter and area occupancy rate of the second inorganic particles in a cross-sectional view are designated as the second equivalent circle diameter and the second area occupancy rate, respectively, wherein the first equivalent circle diameter is smaller than the second equivalent circle diameter, and the first area occupancy rate is smaller than the second area occupancy rate. (2) The ceramic structure according to (1), wherein, in a cross-sectional view, the number of first inorganic particles per unit area is greater than the number of second inorganic particles per unit area. (3) The ceramic structure according to (1) or (2), wherein the first inorganic particles and the second inorganic particles are mainly composed of the same inorganic material. (4) The ceramic structure according to any one of (1) to (3), wherein the first inorganic particles, the second inorganic particles and the main body are mainly composed of the same inorganic material.

[0073] 1 Ceramic structure 10 Main body 10a First surface 10b Second surface 20 Wiring layer 20a First inorganic particles 20b First conductor 30 Via conductor 30a Second inorganic particles 30b Second conductor

Claims

1. A ceramic structure comprising: a main body made of ceramic; a wiring layer located inside the main body along a first surface of the main body; and via conductors electrically and mechanically connected to the wiring layer and extending in a direction intersecting the first surface, wherein the wiring layer and the via conductor each contain a plurality of inorganic particles and a conductor mainly composed of the same metal, and the inorganic particles contained in the wiring layer are designated as first inorganic particles, and the average equivalent circle diameter and area occupancy rate of the first inorganic particles in a cross-sectional view are designated as the first equivalent circle diameter and the first area occupancy rate, respectively, and the inorganic particles contained in the via conductor are designated as second inorganic particles, and the average equivalent circle diameter and area occupancy rate of the second inorganic particles in a cross-sectional view are designated as the second equivalent circle diameter and the second area occupancy rate, respectively, wherein the first equivalent circle diameter is smaller than the second equivalent circle diameter, and the first area occupancy rate is smaller than the second area occupancy rate.

2. The ceramic structure according to claim 1, wherein, in a cross-sectional view, the number of first inorganic particles per unit area is greater than the number of second inorganic particles per unit area.

3. The ceramic structure according to claim 1 or 2, wherein the first inorganic particles and the second inorganic particles are mainly composed of the same inorganic material.

4. The ceramic structure according to any one of claims 1 to 3, wherein the first inorganic particles, the second inorganic particles, and the main body are mainly composed of the same inorganic material.

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