Ceramic heater and manufacturing method thereof

Abstract

The present invention relates to a ceramic heater and a manufacturing method thereof. A ceramic heater according to the present invention comprises: a plate; a shaft; and a bonding layer formed between the plate and the shaft, wherein the plate includes yttria. Specifically, the ceramic heater according to the present invention includes the bonding layer formed between the plate and the shaft, and thus can prevent thermal stress by mitigating heat transferred from the plate to the shaft, and includes the shaft, which has a low thermal conductivity.

Description

Ceramic heater and manufacturing method thereof

[0001] The present invention relates to a ceramic heater and a method for manufacturing the same.

[0002] Conventionally, ceramic substrates have been used in semiconductor devices, semiconductor manufacturing equipment, and the like. For example, in semiconductor manufacturing equipment, a ceramic heater is used in which a flat plate having a heating element inside and a shaft supporting the plate are joined via a joint to hold and heat a semiconductor wafer. The plate and shaft constituting the ceramic heater are sometimes made of materials primarily composed of aluminum nitride (AlN). In this way, these ceramic-based components are joined together by a joint such as an adhesive, or by diffusion bonding, etc.

[0003] Typically, during diffusion bonding, the plate and shaft are composed of the same composition containing yttria, in which case the thermal conductivity of the shaft increases due to yttria. In addition, while the ceramic heater heats the wafer located on top of the heater plate, some of the heat is transferred to the shaft bonded to the heater plate, which causes uneven transfer of thermal energy to the wafer during the semiconductor deposition process, which may cause deterioration of the characteristics and yield of the final semiconductor product. In addition, as thermal stress accumulates at the bonding area during the process of heat leakage to the shaft, cracks may occur and the product lifespan may be shortened. When a shaft that does not contain yttria is bonded to alleviate heat transfer to the shaft, the thermal conductivity of the plate may be locally distorted as the yttria in the plate diffuses into the shaft during the diffusion bonding process, which may reduce the efficiency of heat relief to the wafer.

[0004] The background technology described above is something that the inventor possessed or acquired in the process of deriving the disclosure of the present application, and cannot necessarily be said to be a publicly known technology disclosed to the general public prior to the present application.

[0005] The present invention aims to solve the above-described problem by providing a diffusion-bonded ceramic heater including a shaft with low thermal conductivity and a method for manufacturing the same.

[0006] However, the problems to be solved by the present invention are not limited to the problems mentioned above, and other problems not mentioned can be clearly understood by a person having ordinary skill in the relevant technical field from the description below.

[0007] A ceramic heater according to the present invention comprises: a plate; a shaft; and a bonding layer formed between the plate and the shaft; wherein the plate comprises yttria.

[0008] In one embodiment, the yttria may be present in an amount of 0.01 wt% to 5 wt% of the plate.

[0009] In one embodiment, the shaft may be yttria-free or may contain 0.01 wt% or less of yttria in the shaft.

[0010] According to one embodiment, the bonding layer may be diffusion bonded to the plate and the shaft, and may include a first bonding surface where the plate and the bonding layer are bonded; and a second bonding surface where the bonding layer and the shaft are bonded.

[0011] According to one embodiment, the yttria content within the bonding layer may gradually decrease from the first bonding surface to the second bonding surface.

[0012] According to one embodiment, the bonding layer may include a diffusion layer in which yttria is diffused and distributed by the diffusion bonding, and may include a first diffusion layer including 1 / 3 of the bonding layer from the first bonding surface; a third diffusion layer including 1 / 3 of the bonding layer from the second bonding surface; and a second diffusion layer including a section of the bonding layer excluding the first diffusion layer and the third diffusion layer.

[0013] According to one embodiment, the average yttria content of the first diffusion layer, the average yttria content of the second diffusion layer, and the average yttria content of the third diffusion layer may gradually decrease.

[0014] According to one embodiment, the average yttria content of the first diffusion layer may be 50% to 70% of the average yttria content of the plate.

[0015] In one embodiment, the average yttria content of the second diffusion layer may be 40% to 49% of the average yttria content of the plate.

[0016] According to one embodiment, the average yttria content of the third diffusion layer may be 0.1% to 39% of the average yttria content of the plate.

[0017] According to one embodiment, the average yttria content of the second bonding surface may be 0.01 wt% or less, the porosity of the second bonding surface may be 0.05% to 0.5%, and may include pores having a size of 1 μm or less.

[0018] In one embodiment, the thermal conductivity of the shaft may be 40 W / mK to 100 W / mK, and may be 50% or less of the thermal conductivity of the plate.

[0019] A method for manufacturing a ceramic heater according to the present invention comprises the steps of: preparing a plate, a joint, and a shaft; diffusion-bonding the plate and the joint; polishing one surface of the joint and one surface of the shaft; positioning the polished surfaces of the joint and the shaft so that they are in contact; and diffusion-bonding the joint and the shaft.

[0020] In one embodiment, the plate comprises yttria, and the joint and the shaft prior to diffusion bonding may be yttria-free or of the same composition comprising 0.01 wt% or less of yttria.

[0021] According to one embodiment, the plate includes yttria, the joint after diffusion bonding includes yttria, and the yttria content in the joint after diffusion bonding may gradually decrease from the joint surface with the plate to the joint surface with the shaft.

[0022] According to one embodiment, the step of diffusion bonding the joint and the shaft may be performed at a temperature of 1650° C. to 1850° C. at atmospheric pressure for 0.5 to 10 hours.

[0023] The present invention can provide a ceramic heater including a shaft having low thermal conductivity and a method for manufacturing the same.

[0024] Specifically, the ceramic heater according to the present invention can provide a ceramic heater that includes a joint layer formed between a plate and a shaft, thereby preventing thermal stress by alleviating heat transferred from the plate to the shaft, and including a shaft with low thermal conductivity.

[0025] Figure 1 is a cross-sectional schematic diagram of a ceramic heater according to the present invention.

[0026] Figure 2 is a schematic diagram showing the yttria diffusion distribution of the ceramic heater according to the present invention.

[0027] Figure 3 is an SEM image measuring the yttria content of the plate and bonding layer of the ceramic heater according to the present invention.

[0028] Hereinafter, embodiments are described in detail with reference to the attached drawings. However, the embodiments may be modified in various ways, and the scope of the patent application is not limited or restricted by these embodiments. It should be understood that all modifications, equivalents, or alternatives to the embodiments are included within the scope of the patent application.

[0029] The terms used in the examples are for illustrative purposes only and should not be construed as limiting. Singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, terms such as "comprise" or "have" are intended to specify the presence of a feature, number, step, operation, component, part, or combination thereof described in the specification, but should be understood to not preclude the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0030] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the embodiments pertain. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0031] In addition, when describing with reference to the attached drawings, the same components will be given the same reference numerals regardless of the drawing numbers, and redundant descriptions thereof will be omitted. When describing an embodiment, if it is determined that a detailed description of a related known technology may unnecessarily obscure the gist of the embodiment, the detailed description thereof will be omitted. In addition, when describing a component of an embodiment, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only to distinguish the component from other components, and the nature, order, or sequence of the component is not limited by the terms. When a component is described as being "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0032] Components included in one embodiment and components with common functions will be described using the same names in other embodiments. Unless otherwise stated, the descriptions given in one embodiment can be applied to other embodiments, and detailed descriptions will be omitted to the extent of overlap.

[0033]

[0034] A ceramic heater according to the present invention comprises: a plate; a shaft; and a bonding layer formed between the plate and the shaft; wherein the plate comprises yttria.

[0035] The ceramic heater according to the present invention may include a bonding layer to improve durability by alleviating heat transferred from the plate to the shaft. The plate may have yttria added thereto to increase thermal conductivity for heating the wafer.

[0036] When using a high thermal conductivity plate containing yttria, the heat from the plate may be lost to the shaft during the semiconductor manufacturing process, which may result in uneven heat transfer to the wafer, ultimately leading to deterioration of the characteristics and yield of the final semiconductor product. Accordingly, while a shaft with low thermal conductivity may be desirable for uniform heat transfer to the wafer, local yttria content non-uniformity may occur at the plate joint as the yttria contained in the plate diffuses into the shaft during the shaft bonding process. This may cause non-uniform thermal conductivity of the plate and non-uniform thermal energy transferred to the wafer. Ultimately, this may lead to non-uniform characteristics of the semiconductor produced at different locations on the wafer. In other words, during heating by the ceramic heater, some of the heat may be transferred to the shaft bonded to the plate, which may accumulate thermal stress at the bonding area, causing cracks and shortening the product's lifespan. Alternatively, during diffusion bonding, the yttria in the plate may diffuse into the shaft, increasing the thermal conductivity of the shaft and reducing the heat transfer mitigation efficiency.

[0037] Accordingly, in order to obtain a shaft with low thermal conductivity, the bonding layer of the present invention can act as a buffer to alleviate diffusion of yttria from the plate and alleviate heat transferred to the shaft, and can improve the reliability of the ceramic heater by alleviating thermal stress.

[0038] The ceramic heater may preferably be an aluminum nitride (AlN) ceramic heater. The plate, shaft, and bonding layer may be composed of an AlN material.

[0039] Fig. 1 is a cross-sectional schematic diagram of a ceramic heater according to the present invention. Referring to Fig. 1, the structure of a ceramic heater (100) including a plate (110), a shaft (120), and a bonding layer (130) can be confirmed. The present invention includes a ceramic material structure used in a ceramic heater, and the ceramic heater may include general components such as electrodes and an electric supply rod. The plate (110) may include a high-frequency electrode (not shown), and the shaft (120) may include an electric supply rod (not shown). The plate (110), the bonding layer (130), and the shaft (120) may be diffusion-bonded.

[0040]

[0041] In one embodiment, the yttria may be present in an amount of 0.01 wt% to 5 wt% of the plate.

[0042] The above plate can increase thermal conductivity by including yttria. If the yttria content is below the above range, there may be a problem in which the thermal conductivity is not sufficiently increased, and if it exceeds the above range, there may be a problem in which the thermal conductivity does not increase further and instead decreases.

[0043] The above plate may further include additives such as magnesium oxide or titanium oxide.

[0044]

[0045] In one embodiment, the shaft may be yttria-free or may contain 0.01 wt% or less of yttria in the shaft.

[0046] Preferably, the shaft may be yttria-free. To ensure uniform heat transfer from the plate to the wafer, the shaft may be formed with low thermal conductivity by containing very small amounts of yttria or no yttria at all.

[0047] The above shaft may preferably contain 99.99 wt% or more of aluminum nitride (AlN) among the above shafts.

[0048]

[0049] According to one embodiment, the bonding layer may be diffusion bonded to the plate and the shaft, and may include a first bonding surface where the plate and the bonding layer are bonded; and a second bonding surface where the bonding layer and the shaft are bonded.

[0050] The ceramic heater according to the present invention may be manufactured by diffusion bonding one side of the bonding layer to a plate and the other side to a shaft. By diffusion bonding the bonding layer to the plate and the shaft, a high bonding strength can be secured between the plate and the shaft, thereby ensuring structural stability for long-term use of the ceramic heater. The bonding surface can be formed by the diffusion bonding.

[0051]

[0052] According to one embodiment, the yttria content within the bonding layer may gradually decrease from the first bonding surface to the second bonding surface.

[0053] The above bonding layer may be a result of yttria diffusion from the plate due to diffusion bonding with the plate containing yttria. That is, the first bonding surface, which is the bonding surface with the plate, is adjacent to the plate and has the highest yttria content due to yttria diffusion, and the second bonding surface, which is the bonding surface with the shaft not containing yttria, is far from the plate and has the lowest yttria content due to yttria diffusion. Since the bonding layer is a result of yttria diffusion from the plate, the yttria content may gradually decrease from the first bonding surface to the second bonding surface.

[0054] The yttria content within the above plate may decrease near the first bonding surface. This may be because the yttria within the plate near the first bonding surface has diffused into the bonding layer.

[0055]

[0056] According to one embodiment, the bonding layer may include a diffusion layer in which yttria is diffused and distributed by the diffusion bonding, and may include a first diffusion layer including 1 / 3 of the bonding layer from the first bonding surface; a third diffusion layer including 1 / 3 of the bonding layer from the second bonding surface; and a second diffusion layer including a section of the bonding layer excluding the first diffusion layer and the third diffusion layer.

[0057] The bonding layer may be formed by diffusion bonding with a plate containing yttria, resulting in yttria from the plate diffusing into the bonding layer. The bonding layer may include diffusion layers depending on the degree of yttria diffusion, and may include a first diffusion layer, a second diffusion layer, and a third diffusion layer, sequentially from the first bonding surface.

[0058]

[0059] According to one embodiment, the average yttria content of the first diffusion layer, the average yttria content of the second diffusion layer, and the average yttria content of the third diffusion layer may gradually decrease.

[0060] The first diffusion layer closest to the plate may have the highest average yttria content due to yttria diffusion in the plate, while the third diffusion layer closest to the shaft, which contains little yttria, and furthest from the plate may have the lowest average yttria content due to low yttria diffusion. In other words, since the diffusion layers are yttria diffusion from the plate to the bonding layer, the average yttria content may gradually decrease from the first diffusion layer to the third diffusion layer.

[0061]

[0062] According to one embodiment, the average yttria content of the first diffusion layer may be 50% to 70% of the average yttria content of the plate.

[0063] The first diffusion layer may be adjacent to the plate and may have a high yttria diffusion content. Preferably, the average yttria content may be 50% to 65%; 50% to 60%; 50% to 55%; 55% to 70%; 55% to 65%; 55% to 60%; 60% to 70%; 60% to 65%; or 65% to 70%.

[0064]

[0065] In one embodiment, the average yttria content of the second diffusion layer may be 40% to 49% of the average yttria content of the plate.

[0066] Preferably, the average yttria content may be 40% to 47%; 40% to 45%; 40% to 43%; 43% to 49%; 43% to 47%; 43% to 45%; 45% to 49%; 45% to 47%; or 47% to 49%.

[0067]

[0068] According to one embodiment, the average yttria content of the third diffusion layer may be 0.1% to 39% of the average yttria content of the plate.

[0069] The third diffusion layer may be one that is farther from the plate and thus has less yttria diffusion. Preferably, the average yttria content may be 0.1% to 30%; 0.1% to 20%; 0.1% to 10%; 0.1% to 1%; 1% to 39%; 1% to 30%; 1% to 20%; 1% to 10%; 10% to 39%; 10% to 30%; 10% to 20%; 20% to 39%; 20% to 30%; or 30% to 39%.

[0070] If the average yttria content of the third diffusion layer exceeds the above range, there may be a problem of yttria diffusing into the shaft, thereby increasing thermal conductivity.

[0071]

[0072] According to one embodiment, the average yttria content of the second bonding surface may be 0.01 wt% or less, the porosity of the second bonding surface may be 0.05% to 0.5%, and may include pores having a size of 1 μm or less.

[0073] Preferably, the average yttria content of the second bonding surface may be yttria-free. By including a very small or 0 wt% yttria content in the second bonding surface, yttria diffusion from the plate to the shaft can be prevented. This can address the problem of increased thermal conductivity of the shaft as yttria from the plate migrates toward the shaft.

[0074] Preferably, the porosity may be 0.05% to 0.2%. By exhibiting a porosity and pore size within the above range, excellent physical properties can be exhibited even after bonding.

[0075]

[0076] In one embodiment, the thermal conductivity of the shaft may be 40 W / mK to 100 W / mK, and may be 50% or less of the thermal conductivity of the plate.

[0077] The shaft of the ceramic heater according to the present invention contains a very small amount of yttria or is yttria-free, and thus has low thermal conductivity, enabling uniform heat transfer from the plate to the wafer when the ceramic heater is heated. Preferably, the room temperature thermal conductivity of the shaft may be 80 W / mK to 100 W / mK, and the high temperature thermal conductivity may be 40 W / mK to 60 W / mK.

[0078] The plate may have a thermal conductivity of 150 W / mK to 200 W / mK to transfer heat to the wafer. The plate may have a high thermal conductivity and the shaft may have a low thermal conductivity.

[0079] The thermal conductivity of the shaft may be similar to the thermal conductivity of bulk aluminum nitride (AlN). The bulk aluminum nitride (AlN) may be manufactured under the same conditions as the shaft manufacturing process. Preferably, the difference between the thermal conductivity of the shaft and the thermal conductivity of the aluminum nitride (AlN) may be 7% or less. More preferably, the difference in thermal conductivity at room temperature may be 3% to 7%, and the difference in thermal conductivity at high temperature may be 1% to 2%.

[0080]

[0081] A method for manufacturing a ceramic heater according to the present invention comprises the steps of: preparing a plate, a joint, and a shaft; diffusion-bonding the plate and the joint; polishing one surface of the joint and one surface of the shaft; positioning the polished surfaces of the joint and the shaft so that they are in contact; and diffusion-bonding the joint and the shaft.

[0082] The diffusion bonding of the above ceramic heater can be performed separately for the diffusion bonding of the plate and the joint, and for the diffusion bonding of the joint and the shaft, or can be performed simultaneously if necessary.

[0083] The method for manufacturing a ceramic heater according to the present invention can provide a method for manufacturing a joint by diffusion bonding, in order to solve the problem of cracks caused by thermal stress due to the difference in thermal conductivity between the plate and the shaft and the problem of increased thermal conductivity of the shaft, in order to provide a ceramic heater including a plate having high thermal conductivity and a shaft having low thermal conductivity.

[0084] The above-described preparation step may preferably be preparing a sintered body of each of the plate, the joint, and the shaft. Here, the joint body is a sintered body that forms a joint layer for joining the plate and the shaft, and may have a shape identical to the shape of the shaft joint surface, and may be in the shape of a ring or disk that is larger than or equal to the area of ​​the shaft's contact surface.

[0085] The above polishing process step may be to polish the non-diffusion-bonded surface of the plate and the diffusion-bonded joint and one surface of the shaft to obtain a flat surface, thereby preventing problems of pores and cracks occurring during diffusion bonding.

[0086] The method for manufacturing a ceramic heater according to the present invention can prevent degradation of properties or secure physical properties through diffusion bonding. Since diffusion bonding does not significantly change the microstructure based on the bonding interface, it can prevent degradation of properties due to bonding and secure physical properties such as maintaining mechanical strength similar to the bulk state of the base material and the component. In addition, the present invention can prevent yttria from diffusing into the shaft even after diffusion bonding, including the bonded body.

[0087]

[0088] In one embodiment, the plate comprises yttria, and the joint and the shaft prior to diffusion bonding may be yttria-free or of the same composition comprising 0.01 wt% or less of yttria.

[0089] The joint and shaft prior to diffusion bonding may preferably be yttria-free. More preferably, they may be pure aluminum nitride (AlN). The joint and the shaft may be composed of the same composition.

[0090] The above shaft can form a low thermal conductivity by containing or not containing a very small amount of yttria, and the joint can prevent yttria from diffusing from the plate to the shaft by containing or not containing a very small amount of yttria, thereby providing an effect of alleviating heat transferred to the shaft.

[0091]

[0092] According to one embodiment, the plate includes yttria, the joint after diffusion bonding includes yttria, and the yttria content in the joint after diffusion bonding may gradually decrease from the joint surface with the plate to the joint surface with the shaft.

[0093] The joint after diffusion bonding may contain yttria as yttria diffuses from the plate containing yttria. The joint surface with the plate may have the highest yttria content due to yttria diffusion, and the joint surface with the shaft may have the lowest yttria content due to yttria diffusion. Accordingly, the yttria content in the joint may gradually decrease toward the joint surface with the shaft as yttria diffuses from the plate. As the yttria content approaches 0% near the joint surface with the shaft, a shaft with low thermal conductivity can be secured.

[0094] After diffusion bonding, the yttria content within the plate near the bonding surface of the plate and the bonding body may decrease compared to before diffusion bonding as the yttria within the plate diffuses into the bonding layer.

[0095]

[0096] According to one embodiment, the step of diffusion bonding the joint and the shaft may be performed at a temperature of 1650° C. to 1850° C. at atmospheric pressure for 0.5 to 10 hours.

[0097] Preferably, the temperature may be 1650°C to 1800°C; 1650°C to 1750°C; 1650°C to 1700°C; 1700°C to 1850°C; 1700°C to 1800°C; 1700°C to 1750°C; 1750°C to 1850°C; 1750°C to 1800°C; or 1800°C to 1850°C.

[0098] Preferably, the time may be 0.5 hours to 8 hours; 0.5 hours to 6 hours; 0.5 hours to 4 hours; 0.5 hours to 2 hours; 2 hours to 10 hours; 2 hours to 8 hours; 2 hours to 6 hours; 2 hours to 4 hours; 4 hours to 10 hours; 4 hours to 8 hours; 4 hours to 6 hours; 6 hours to 10 hours; 6 hours to 8 hours; or 8 hours to 10 hours. The time may include the time after charging, operation, and cooling before charging.

[0099] Temperature and time can affect the properties of a product after diffusion bonding. Diffusion bonding performed within the above conditions can produce a low porosity and small pore size, resulting in an excellent product.

[0100] If the temperature and time are below the above range, there may be a problem with poor bonding, and if they exceed the above range, there may be a problem with changes in the microstructure of the bonding interface. Specifically, if the temperature is low, the interfacial diffusion activity of the microstructure required for diffusion bonding may not occur, or if a situation occurs where more pressure than necessary must be applied for sufficient diffusion activity, it may cause deformation of the shape of the pressurized area, and if the time is insufficient, the problem with poor bonding may occur due to difficulty in securing sufficient diffusion activity. If the temperature is high, it may cause changes in the microstructure, such as excessive grain growth, at the bonding interface, so that the microstructures (crystal grains) of the bonded and non-bonded surfaces may be different, which may locally cause changes in the thermal, electrical, and physical properties of the plate. If the time is exceeded, the problem of changes in the microstructure of the bonding interface may occur due to excessive diffusion activity.

[0101]

[0102] Hereinafter, the present invention will be described in more detail by way of examples and comparative examples.

[0103] However, the following examples are only intended to illustrate the present invention, and the content of the present invention is not limited to the following examples.

[0104]

[0105] Example

[0106] A plate sintered body was prepared by adding 3.5 wt% of yttria to aluminum nitride (AlN) raw powder and sintering under pressure sintering conditions, and an yttria-free joint body composed of aluminum nitride that underwent the same process as the plate was prepared. The shaft sintered body was prepared by pressureless sintering through a general ceramic process. After diffusion bonding the plate and joint body, polishing was performed, and a shaft was diffusion bonded to manufacture a ceramic heater.

[0107]

[0108] Experimental example

[0109] The yttria distribution in the ceramic heater was confirmed.

[0110] Fig. 2 is a schematic diagram showing the yttria diffusion distribution of the ceramic heater according to the present invention, in which the higher the yttria content, the darker the drawing is. It shows that the markings of each layer become lighter as it goes from the first bonding surface (140) to the second bonding surface (150). Fig. 3 is a SEM image measuring the yttria content of the plate and bonding layer of the ceramic heater according to the present invention, and the yttria distribution can be confirmed. The EDS measurement values ​​measuring the change in yttria content and the yttria distribution map compared to the plate are shown in Table 1 below.

[0111] Plate 1st diffusion layer (131) 2nd diffusion layer (132) 3rd diffusion layer (133) EDS Yttria content 2.52 1.51.19 0.94 Yttria distribution (%) 100 60 47 37

[0112] Referring to Figures 2, 3, and Table 1, it can be confirmed that the yttria content decreases with distance from the plate. Accordingly, it can be confirmed that yttria does not diffuse into the shaft, resulting in low thermal conductivity. Table 2 below shows a comparison of the thermal conductivities of the AlN bulk material and the shaft.

[0113] Temperature (℃) Room temperature 100 200 300 400 500 AlN bulk thermal conductivity (W / mK) 109.78 8.47 5.43 64.95 6.87 50.52 Shaft thermal conductivity (W / mK) 102.39 88.77 74.66 5.55 7.47 51 Reduction rate compared to bulk (%, absolute value) 6.66 0.41 1.10.92 1.06 0.95

[0114] Referring to Table 2, it can be confirmed that the thermal conductivity of the shaft is similar to that of pure AlN material without yttria, and thus, no loss in the thermal conductivity of the shaft occurs.

[0115] Although the embodiments have been described above, those skilled in the art will appreciate that various technical modifications and variations can be applied based on the above. For example, appropriate results can still be achieved even if the described techniques are performed in a different order than described, and / or components of the described systems, structures, devices, circuits, etc. are combined or combined in a different manner than described, or are replaced or substituted with other components or equivalents.

[0116] Therefore, other implementations, other embodiments, and equivalents to the claims also fall within the scope of the claims described below.

Claims

1. A plate; a shaft; and a bonding layer formed between the plate and the shaft; The above plate contains yttria, Ceramic heater.

2. In paragraph 1, The above yttria is 0.01 wt% to 5 wt% of the plate, Ceramic heater.

3. In paragraph 1, The above shaft, It is Itria-free, or The shaft contains yttria in an amount of 0.01 wt% or less, Ceramic heater.

4. In paragraph 1, The above bonding layer is diffusion bonded to the plate and the shaft, It comprises a first bonding surface where the plate and the bonding layer are bonded; a second bonding surface where the bonding layer and the shaft are bonded; Ceramic heater.

5. In paragraph 4, The yttria content in the above bonding layer is It gradually decreases from the first bonding surface to the second bonding surface, Ceramic heater.

6. In paragraph 4, The above bonding layer includes a diffusion layer in which yttria is diffused and distributed by the diffusion bonding, A first diffusion layer including 1 / 3 of the section of the bonding layer from the first bonding surface; A third diffusion layer including 1 / 3 of the section of the bonding layer from the second bonding surface; A second diffusion layer including a section excluding the first diffusion layer and the third diffusion layer of the above bonding layer; Ceramic heater.

7. In paragraph 6, The average yttria content of the first diffusion layer, the average yttria content of the second diffusion layer, and the average yttria content of the third diffusion layer gradually decrease. Ceramic heater.

8. In paragraph 6, The average yttria content of the first diffusion layer is 50% to 70% of the average yttria content of the plate. Ceramic heater.

9. In paragraph 6, The average yttria content of the second diffusion layer is 40% to 49% of the average yttria content of the plate. Ceramic heater.

10. In paragraph 6, The average yttria content of the third diffusion layer is 0.1% to 39% of the average yttria content of the plate. Ceramic heater.

11. In paragraph 5, The average yttria content of the second bonding surface is 0.01 wt% or less, The porosity of the second bonding surface is 0.05% to 0.5%, Containing pores having a size of 1 ㎛ or less, Ceramic heater.

12. In paragraph 1, The thermal conductivity of the above shaft is 40 W / mK to 100 W / mK, The thermal conductivity of the above plate is 50% or less, Ceramic heater.

13. Step of preparing the plate, joint and shaft; A step of diffusion bonding the above plate and the above joint; A step of polishing one side of the joint and one side of the shaft; A step of positioning the polishing surfaces of the above joint and the shaft so that they are in contact; and A step of diffusion bonding the above joint and the shaft; comprising; Method for manufacturing a ceramic heater.

14. In paragraph 13, The above plate contains yttria, The joint and the shaft before the diffusion bonding are yttria-free or have the same composition containing 0.01 wt% or less of yttria. Method for manufacturing a ceramic heater.

15. In paragraph 14, The above plate contains yttria, The above-mentioned joint after the diffusion bonding contains yttria, The yttria content in the joint after the diffusion bonding gradually decreases from the joint surface with the plate to the joint surface with the shaft. Method for manufacturing a ceramic heater.

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