Ceramic susceptor

Abstract

To provide a ceramic susceptor.SOLUTION: The susceptor includes an insulating plate in which a heating element is disposed, and a shaft joined to a bottom portion of the insulating plate. The heating element includes a first heating element pattern including a first resistance section and a first connecting section connected between a first pair of terminals. In a plan view of the first resistance section projected onto the insulating plate, the first resistance section includes a first central resistance section disposed within a smaller diameter region than a joint portion between the insulating plate and the shaft.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] The present invention relates to a ceramic susceptor, and more particularly to a ceramic susceptor for improving temperature uniformity and improving the life of a heater pattern.

Background Art

[0002] Generally, a semiconductor device or a display device is manufactured by a method in which a plurality of thin film layers including a dielectric layer and a metal layer are sequentially laminated on a glass substrate, a flexible substrate, or a semiconductor wafer substrate and then patterned. These thin film layers are sequentially deposited on the substrate by a chemical vapor deposition (CVD) process or a physical vapor deposition (PVD) process. The CVD process includes a low pressure chemical vapor deposition (LPCVD) process, a plasma enhanced chemical vapor deposition (PECVD) process, a metal organic CVD (MOCVD) process, and the like. In such CVD apparatuses and PVD apparatuses, a ceramic susceptor for supporting a glass substrate, a flexible substrate, a semiconductor wafer substrate, etc. and generating predetermined heat or generating plasma by a radio frequency (RF) electrode is disposed. The ceramic susceptor is widely used in a plasma deposition process or the like in accordance with accurate temperature control and heat treatment requirements for high-precision processes such as wiring miniaturization of semiconductor elements, and is also used for plasma formation and substrate heating in an etching process of a thin film layer formed on a semiconductor wafer substrate or a baking process of a photoresist.

[0003] A general ceramic susceptor includes a heating element for heater function disposed between ceramic materials. In a ceramic susceptor structure, when the heating element receives power supply and generates heat to heat a semiconductor wafer substrate or the like, the temperature uniformity of the substrate is important for improving the yield by a stable semiconductor process.

[0004] FIG. 1 is a diagram illustrating a heating element pattern of a conventional ceramic susceptor.

[0005] Referring to FIG. 1, a conventional ceramic susceptor generally includes a heating element pattern 10 that extends while drawing an arc from terminal pairs 10a and 10b at the center on the same plane. The conventional heating element pattern 10 includes a hairpin section 20 that is a section that bends suddenly for bending in a narrow region at the center. That is, the hairpin section 20 near the terminal pairs 10a and 10b has a sharp curve form in which the radius of curvature is smaller than the radius of curvature of the adjacent bent section.

[0006] However, such a hairpin section 20 is an area where the pattern density per unit area is high and the heat generation density is high, so cracks are likely to occur due to long-term use. This is due to the thermal stress caused by the difference in the coefficient of thermal expansion of the heating element embedded in the ceramic material. The ceramic susceptor used particularly in the vapor deposition process in the semiconductor process is exposed to a repeated heat cycle environment, so cracks continue to occur on the surface of the ceramic susceptor, its function deteriorates, and it becomes unusable. SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Therefore, the present invention has been devised to solve the above-described problems, and an object of the present invention is to form a heating element pattern without a hairpin section in the central portion of a susceptor plate having a high embedding density of the heating element, thereby improving the temperature uniformity in the entire area of the upper surface of the susceptor and providing a ceramic susceptor for improving the life of the heater pattern. MEANS FOR SOLVING THE PROBLEMS

[0008] First, to summarize the features of the present invention, a susceptor according to one aspect of the present invention for achieving the above object includes an insulating plate on which a heating element is disposed; and a shaft joined to the lower portion of the insulating plate. The heating element includes a first heating element pattern including a first resistance portion and a first connection portion connected between a first terminal pair. The first resistance portion may include a first central resistance portion disposed within a diameter region smaller than a joint portion between the insulating plate and the shaft in a plan view of projecting the insulating plate.

[0009] The first resistance portion includes a plurality of arc portions connected in the circumferential direction and a plurality of bent portions connecting the arc portions. The curve of the first central resistance portion may be formed to meet an extension line of a virtual straight line passing through a spaced space between adjacent bent portions.

[0010] The first resistance portion includes a plurality of arc portions connected in the circumferential direction and a plurality of bent portions connecting the arc portions. The curve of the first central resistance portion may be formed to meet an extension line extended from the bent portion closest to the first central resistance portion.

[0011] The curve of the first central resistance portion may be formed such that a curvature radius of a portion close to any one of the first terminal pair is larger than a curvature radius at the bent portion of the first resistance portion.

[0012] The curvature radius of a portion close to any one of the first terminal pair may be two times or more the maximum curvature radius of the bent portion of the first resistance portion.

[0013] The curve of the first central resistance portion may be formed such that a curvature radius of a portion close to any one of the first terminal pair is larger than a curvature radius of the closest bent portion among the bent portions of the first resistance portion.

[0014] The curve of the first central resistance portion is formed such that the radius of curvature of a portion close to any one of the first terminal pairs is larger than the radius of curvature of the most adjacent bent portion among the bent portions of the first resistance portion. The curve of the second central resistance portion may be formed such that the radius of curvature of a portion close to any one of the second terminal pairs is larger than the radius of curvature of the most adjacent bent portion among the bent portions of the second resistance portion.

[0015] The first terminal pair may be disposed within a diameter region smaller than the joint portion of the insulating plate and the shaft.

[0016] The heating element includes a second heating element pattern including a second resistance portion and a second connecting portion connected between the second terminal pairs. In a plan view of projecting the insulating plate, the first resistance portion and the second resistance portion are disposed within a diameter region smaller than the joint portion of the insulating plate and the shaft, and may include a second central resistance portion of the second resistance portion.

[0017] The second resistance portion includes a plurality of arc portions connected in the circumferential direction and a plurality of bent portions connecting the arc portions. One or more of the curves of the first central resistance portion and the second central resistance portion may be formed to meet an extension line of an imaginary straight line passing through a spaced space between adjacent bent portions.

[0018] The adjacent bent portions may include the bent portions of the first resistance portion and the bent portions of the second resistance portion where the bent portions are adjacent.

[0019] The second resistance portion includes a plurality of arc portions connected in the circumferential direction and a plurality of bent portions connecting the arc portions. One or more of the curves of the first central resistance portion and the second central resistance portion may be formed to meet an extension line extended from the bent portion of the first central resistance portion that is most adjacent to the first central resistance portion or the second central resistance portion.

[0020] The second resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bending parts connecting the arc parts. One or more of the curves of the first central resistance part and the curves of the second central resistance part may be formed to meet a virtual extension line extending from the bending part of the second central resistance part that is closest to the first central resistance part or the second central resistance part.

[0021] The second resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bending parts connecting the arc parts. One or more of the curves of the first central resistance part and the curves of the second central resistance part may be formed to meet the respective virtual extension lines extending from the bending parts of the first central resistance part and the second central resistance part that are closest to the first central resistance part and the second central resistance part, respectively.

[0022] For the curves of the first central resistance part and the curves of the second central resistance part, the radius of curvature of a part close to any one of the respective terminal pairs may be formed to be larger than the radius of curvature at the bending parts of the first resistance part and the second resistance part, respectively.

[0023] The radius of curvature of a part close to any one of the respective terminal pairs may be not less than twice the maximum radius of curvature of the bending parts of the first resistance part and the second resistance part.

[0024] The second terminal pair may be arranged within a diameter region smaller than the joint part of the insulating plate and the shaft.

Advantages of the Invention

[0025] According to the ceramic susceptor of the present invention, by forming a heating element pattern without a hairpin section in the central part of the susceptor plate with a high embedding density of the heating element, the temperature uniformity can be improved over the entire area of the upper surface of the susceptor, and the life of the heater pattern can be extended very significantly.

Brief Description of the Drawings

[0026] The accompanying drawings, which are included as a part of the detailed description to assist in understanding the present invention, provide examples of embodiments according to the present invention and explain the technical concept of the present invention together with the detailed description.

[0027]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4A

Figure 4B

Figure 5A

Figure 5B

DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. Here, the same reference numerals are given to the same components as much as possible in each figure. Further, detailed descriptions of already known functions and / or configurations are omitted. The content disclosed below focuses on the parts necessary for understanding the operations according to various embodiments, and omits the descriptions of the elements that may obscure the gist of the description. In addition, some of the components in the drawings can be illustrated exaggeratedly, omitted, or schematically. The size of each component does not entirely reflect the actual size, and therefore, the content described herein is not limited by the relative size and interval of the components depicted in each figure.

[0029] When describing embodiments of the present invention, if it is determined that a detailed description of the known technology related to the present invention may obscure the gist of the present invention, the detailed description thereof will be omitted. The terms described hereinafter are terms defined in consideration of the functions in the present invention, and they can be changed depending on the intention or convention of the user, operator, etc. Therefore, the definition should be given based on the content throughout this specification. The terms used in the detailed description are merely for describing the embodiments of the present invention and should never be restrictive. Unless otherwise specified, the singular form of the expression includes the meaning of the plural form. In this description, expressions such as "including" or "comprising" are for indicating a certain characteristic, number, step, operation, element, part thereof or combination, and should not be construed as excluding the existence or possibility of one or more other characteristics, numbers, steps, operations, elements, parts thereof or combinations other than those described.

[0030] Note that terms such as first and second may be used to describe various components, but these components are not limited by these terms, and these terms are only used for the purpose of distinguishing one component from another.

[0031] FIG. 2 is a schematic cross-sectional view showing a ceramic susceptor 100 according to an embodiment of the present invention.

[0032] Referring to FIG. 2, a (ceramic) susceptor 100 according to an embodiment of the present invention includes an insulating plate 110 and a shaft 120.

[0033] A ceramic susceptor 100 according to an embodiment of the present invention is a semiconductor device for supporting various target substrates for processing such as semiconductor wafers, glass substrates, flexible substrates, etc., and heating the target substrate to a predetermined temperature or using it in a semiconductor process using plasma for plasma enhanced chemical vapor deposition, dry etching, etc.

[0034] The insulating plate 110 may be configured such that electrodes 112 for plasma generation and / or a heating element (electrode) 114 for substrate heating are arranged (embedded) at a predetermined interval between ceramic materials. The insulating plate 110 is configured to enable semiconductor processes using substrate heating by the heating element 114 and / or plasma by the electrodes 112 while stably supporting the substrate to be processed.

[0035] In the ceramic susceptor 100 of the present invention, although not shown, it is also possible that the electrode 112 is used for plasma generation and, additionally, a chuck electrode with an electrostatic chuck function is further arranged to support the substrate 11 placed on the insulating plate 110. For example, the chuck electrode may be further configured to be arranged (embedded) at a predetermined interval above or below the electrode 112 or the heating element 114.

[0036] The insulating plate 110 may be formed of a plate-like structure having a predetermined shape. For example, the insulating plate 110 may be formed of a circular plate-like structure, but is not necessarily limited thereto. Here, the ceramic material may be at least one of Al2O3, Y2O3, Al2O3 / Y2O3, ZrO2, AlC (Autoclaved lightweight concrete), TiN, AlN, TiC, MgO, CaO, CeO2, TiO2, B x C y , BN, SiO2, SiC, YAG, mullite (Mullite), AlF3, and preferably may be aluminum nitride (AlN). Each ceramic powder may selectively contain about 0.1 to 10%, preferably about 1 to 5% of yttrium oxide powder.

[0037] The shaft 120 has a hollow shape with a through-hole and is joined or coupled to the lower surface of the insulating plate 110. The shaft 120 may be formed of the same ceramic material as the insulating plate 110 and joined or coupled.

[0038] The electrode 112 or the chuck electrode may be made of tungsten (W), molybdenum (Mo), silver (Ag), gold (Au), niobium (Nb), titanium (Ti), aluminum nitride (AlN), or an alloy thereof, and preferably may be made of molybdenum (Mo). The electrode 112 may be connected to an RF (Radio) power source or grounded via a connecting rod 121 housed in the hollow shaft 120, and the chuck electrode may be connected to a power source for driving the chuck electrode (DC or AC power source) via another connecting rod housed in the hollow shaft 120. The electrode 112 may have a wire type or sheet typ mesh structure. Here, the mesh structure is a net-like structure formed such that a plurality of metals arranged in a first direction and a plurality of metals arranged in a second direction are shifted from each other and intersect.

[0039] The heating element 114 is made of tungsten (W), molybdenum (Mo), or an alloy or carbide thereof, and has a high melting point and high resistivity. The heating element 114 may be formed in a plate-like coil form by a heating wire (or a resistance wire or a heating electrode). Further, the heating element 114 may be formed in a multilayer structure for precise temperature control. Such a heating element 114 is connected to a power source via a connecting rod 123 housed in the hollow shaft 120 in a semiconductor manufacturing process, and can function to heat a substrate to be processed on the insulating plate 110 to a predetermined constant temperature in order to perform a smooth deposition process and an etching process.

[0040] In the ceramic susceptor 100 according to an embodiment of the present invention, a heating element 114 made of a heating wire (or a resistance wire) forms a heating element pattern without a hairpin section as shown in FIG. 1 in the central portion SR of the susceptor plate with a high embedding density, that is, in a diameter region SR smaller than the joint portion between the insulating plate 110 and the shaft 120, as shown in FIGS. 3A to 5B. This makes it possible to improve the temperature uniformity in the entire region of the susceptor upper surface and to very significantly extend the life of the heater pattern.

[0041] That is, the heating element pattern disposed in the diameter region SR smaller than the joint portion between the insulating plate 110 and the shaft 120 is formed of a curve that bends at 90° or more (for example, 90 to 270°) without a sharp curve. Here, the sharp curve may include a case where the radius of curvature decreases and then increases, or increases and then decreases.

[0042] Hereinafter, such a configuration of the present invention will be specifically described with reference to FIGS. 3A to 4B.

[0043] FIG. 3A is an example of the pattern of the heating element 114 of the ceramic susceptor 100 of the present invention.

[0044] Referring to FIG. 3A, the heating element 114 may include a heating element pattern including a first resistance portion 91 and a first connection portion 92 connected between the first terminal pair 71a and 71b. The resistance portion 91 may include a plurality of arc portions 85 connected in the circumferential direction and a plurality of bent portions 86 connecting the arc portions.

[0045] The first connection portion 92 is a connection line portion for electrically connecting to the first terminal pair 71a and 71b at both ends of the first resistance portion 91. The first resistance portion 91 and the first connection portion 92 are made of a material with high resistance, such as tungsten (W), molybdenum (Mo), or their alloys and carbides. The resistance portion 91 is a portion where the above material is processed into a coil shape (in some cases, a sawtooth zigzag shape is also possible) to increase the resistance by increasing the electron movement distance.

[0046] In a plan view of the first resistance portion 91 when projected onto the insulating plate 110, the first central resistance portion 910 disposed within the diameter region SR smaller than the joint portion between the insulating plate 110 and the shaft 120 may be formed of a curve that bends at 90° or more (for example, 90 to 270°) without a sharp curve. The first terminal pair 71a and 71b are preferably also disposed within the diameter region SR smaller than the joint portion between the insulating plate 110 and the shaft 120, but may be disposed in other regions in some cases.

[0047] That is, the curve of the first central resistance portion 910 means a curve without a sharp curve in the pattern of the first resistance portion 91 disposed in the region SR smaller than the joint portion of the shaft 120. When a sharp curve section as described above appears, a hairpin section as shown in FIG. 1 is generated, which is disadvantageous to the temperature uniformity and the life of the heating element pattern. Therefore, the curve of the first central resistance portion 910 may be composed of a portion where the extension lines before and after it bend at 90° or more (for example, 90 to 270°) at the bending points B1 and B2 of the curve, that is, without a sharp curve.

[0048] FIG. 3B is a diagram for explaining the sharp curve portion of the curve of the conventional resistance portion in FIG. 1. Referring to FIG. 3B, the resistance portion at the center of the conventional plate as shown in FIG. 1 has a sharp curve form in which the radius of curvature at the bending point A1 of the curve of the hairpin section near the terminal pairs 10a and 10b is smaller than the radius of curvature of the adjacent bent portion. Such a sharp curve form may be, for example, a form in which the extension lines A1-1 and A1-2 before and after the bending point A1 bend at less than 90°. Since this is a region where the pattern density per unit area is high and the heat generation density is high, cracks are likely to occur due to long-term use.

[0049] FIG. 3C is a diagram for explaining the change of the curve of the central resistance portion 910 of the present invention. Referring to FIG. 3C, the curve of the first central resistance portion 910 of the present invention is composed of a portion that bends at the one or more bending points B1 and B2 of the curve such that the extension lines before and after it intersect at 90° or more (for example, 90 to 270°), so it can be designed without a sharp curve section. For example, the extension lines before and after at the bending point B1 may be a first extension line connecting the terminal (for example, 71a) or a previous bending point (not shown) and the bending point B1, and a second extension line connecting the bending points B1 and B2. Also, the extension lines before and after at the bending point B2 may be a first extension line connecting the bending points B1 and B2, and a second extension line connecting the bending point B2 and the next bending point (not shown).

[0050] In addition, the curve of the first central resistance portion 910 disposed within the region SR smaller than the joint portion of the shaft 120 is preferably formed so as to meet at least once with an extension line of a virtual straight line LL passing through a spaced-apart space between adjacent bent portions 86 of the resistance portion 91, like the point PL in FIG. 3A. The spaced-apart space between the adjacent bent portions 86 includes the spaced-apart space between at least a pair of opposing bent portions 86. However, the opposing bent portions 86 do not necessarily have to be formed symmetrically with respect to a line as shown in the drawing, and it is sufficient that they are spaced apart. In FIG. 3A, it is assumed that the spaced-apart space between the adjacent bent portions 86 is the spaced-apart space between three pairs of opposing bent portions 86.

[0051] Thus, when the meeting points PL / PL1 / PL2 exist, the empty space without the resistance portion 91 pattern between the bent portions 86 is not extended into the region SR smaller than the joint portion of the shaft 120. In this case, it becomes possible to improve the temperature uniformity around the resistance portion 91 pattern at the meeting point PL / PL1 / PL2 portion.

[0052] FIG. 4A is an example of a two-zone arrangement structure of the pattern of the heating element 114 of the ceramic susceptor 100 of the present invention.

[0053] FIG. 4B is another example of a two-zone arrangement structure of the pattern of the heating element 114 of the ceramic susceptor 100 of the present invention.

[0054] In FIGS. 4A and 4B, the arrangement positions of the central resistance portions 910-1 and 910-2 are different.

[0055] Referring to FIGS. 4A and 4B, the heating element 114 may include a first heating element pattern 411 including a first resistance portion 91-1 and a first connection portion 92-1 connected between a first terminal pair 81a, 81b, and a second heating element pattern 412 including a second resistance portion 91-2 and a second connection portion 92-2 connected between a second terminal pair 82a, 82b. Each of the resistance portions 91-1 / 91-2 may include a plurality of arc portions 85-1 / 85-2 connected in the circumferential direction and a plurality of bent portions 86-1 / 86-2 connecting the arc portions to each other.

[0056] Each of the connection portions 92-1 / 92-2 is a connection line portion for electrically connecting to the terminal pairs 81a, 81b / 82a, 82b at both ends of each of the resistance portions 91-1 / 91-2. The first resistance portion 91 and the first connection portion 92 are made of a material with high resistance, such as tungsten (W), molybdenum (Mo), or their alloys or carbides. The resistance portion 91 is a portion where the above material is processed into a coil shape (in some cases, a sawtooth zigzag shape is also possible) to increase the electron movement distance and thus enhance the resistance.

[0057] In a plan view of projecting the insulating plate 110 onto each of the first resistance portion 91-1 and the second resistance portion 91-2, a first central resistance portion 910-1 of the first resistance portion 91-1 and a second central resistance portion 910-2 of the second resistance portion 91-2 disposed within a diameter region SR smaller than the joint portion between the insulating plate 110 and the shaft 120 may each consist only of curves without sharp curves or straight portions. The first terminal pair 81a, 81b and the second terminal pair 82a, 82b are preferably disposed within a diameter region SR smaller than the joint portion between the insulating plate 110 and the shaft 120, but may be disposed in other regions in some cases.

[0058] That is, the curves of the central resistance portions 910-1, 910-2 may each consist of curves where the respective resistance portion 91-1 / 91-2 patterns disposed within the region SR smaller than the joint portion of the shaft 120 are bent at 90° or more (for example, 90 to 270°) without sharp curves.

[0059] Note that, among the central resistance portions 910-1 and 910-2 arranged in the region SR smaller than the joint portion of the shaft 120, one or more (for example, 910-2) of the curves are preferably formed so as to meet one or more times with an extension line of a virtual straight line LL passing through a spaced space between adjacent bent portions 86-1 and 86-2 of the resistance portions 91-1 and 91-2, like the point PL in FIG. 4A. The spaced space between the adjacent bent portions 86-1 and 86-2 of the resistance portions 91-1 and 91-2 includes at least a spaced space between the bent portion 86-1 of the first resistance portion 91-1 and the bent portion 86-2 of the second resistance portion 91-2 that face each other. However, the facing bent portions 86-1 and 86-2 do not necessarily have to be formed symmetrically with respect to a line as shown in the drawing, and it is sufficient that they are spaced apart. FIG. 4A shows that the spaced space between the adjacent bent portions 86-1 and 86-2 is a spaced space between three pairs of facing bent portions 86.

[0060] FIG. 5A is an enlarged view of the PP1 portion in FIG. 4A.

[0061] Referring to FIG. 5A, one or more of the curves of any one of the central resistance portions 910-1 and 910-2 arranged in the region SR smaller than the joint portion of the shaft 120 may be formed so as to meet with a virtual extension line LL1 extending from the bent portion 86-11 of the first central resistance portion 910-1 that is closest to the first central resistance portion 910-1 or the second central resistance portion 910-2, like the point PL1. Also, one or more of the curves of any one of the central resistance portions 910-1 and 910-2 arranged in the region SR smaller than the joint portion of the shaft 120 may be formed so as to meet with a virtual extension line LL2 extending from the bent portion 86-21 of the second central resistance portion 910-2 that is closest to the first central resistance portion 910-1 or the second central resistance portion 910-2, like the point PL2.

[0062] FIG. 5B is an enlarged view of the PP2 portion in FIG. 4B.

[0063] Referring to FIG. 5B, any one or more of the curves of the central resistance portions 910-1 and 910-2 disposed within the region SR smaller than the joint portion of the shaft 120 may be formed to meet the virtual extension lines LL1 and LL2 extending from the bent portions 86-11 of the first central resistance portion 910-1 and the bent portions 86-21 of the second central resistance portion 910-2 that are respectively closest to the first central resistance portion 910-1 and the second central resistance portion 910-2, like the points PL1 and PL2.

[0064] When there are such meeting points PL / PL1 / PL2 as described above, the empty space without the resistance portion 91 pattern between the bent portions 86 does not extend into the region SR smaller than the joint portion of the shaft 120. In this case, it becomes possible to improve the temperature uniformity around the meeting points PL / PL1 / PL2 by the pattern of the resistance portion 91 at these points.

[0065] Also, in FIGS. 5A and 5B, the respective curves of the central resistance portions 910-1 and 910-2 disposed within the region SR smaller than the joint portion of the shaft 120 include a section with a radius of curvature RC1 (e.g., R7) close to the terminal side of the central resistance portion, a section with a radius of curvature RC2 (e.g., R2.5) between the central resistance portion and the bent portion 86-1, a section with a radius of curvature RC3 (e.g., R3.5) between the other arc portion 85 and the bent portion 86-1, and so on. Here, the unit of the numerical value of the radius of curvature for R7, R3.5, and R2.5 is mm.

[0066] Here, for the sake of convenience, the radius of curvature for the first resistance portion 91-1 and the first central resistance portion 910-1 is exemplified, but such a relationship may also be applied to the radius of curvature for the second resistance portion 91-2 and the second central resistance portion 910-2. Note that such a relationship may be applied to both the first resistance portion 91-1 and the first central resistance portion 910-1, and the second resistance portion 91-2 and the second central resistance portion 910-2.

[0067] Similarly, such a relationship may also be applied to the first resistance portion 91 and the first central resistance portion 910 in FIG. 3A. That is, in FIG. 3A, among one or more of the curves of the central resistance portion 910 connected to the first terminal pair 71a, 71b within the region SR smaller than the joint portion of the shaft 120, the curvature radius RC1 (e.g., R7) section close to the terminal side (e.g., 71a) of the central resistance portion 910, the curvature radius RC2 (e.g., R2.5) section between the central resistance portion 910 and the bent portion 86, the curvature radius RC3 (e.g., R3.5) section between the other arc portion 85 and the bent portion 86, etc. are included.

[0068] In other words, for each of the curves of the central resistance portions 910-1, 910-2 arranged within the region SR smaller than the joint portion of the shaft 120, the curvature radius (e.g., R7) of a portion close to any one of the terminal pairs 81a, 81b / 82a, 82b may be formed larger than the curvature radii (e.g., R2.5, R3.5, etc.) at all other bent portions 86-1, 86-2. At this time, the curvature radius (e.g., R7) of a portion close to any one of the terminal pairs 81a, 81b / 82a, 82b may be formed more than twice as large as the maximum curvature radius (e.g., R3.5) at all other bent portions 86-1, 86-2.

[0069] Note that for the curve of the first central resistance portion 910-1, the curvature radius (e.g., RC1 = R7) of a portion close to any one of the first terminal pair 81a, 81b may be formed larger than the curvature radius (e.g., RC2 = R2.5) of the most adjacent bent portion among the bent portions of the first resistance portion 91-1. Similarly, for the curve of the second central resistance portion 910-2, the curvature radius (e.g., RC1 = R7) of a portion close to any one of the second terminal pair 82a, 82b may be formed larger than the curvature radius (e.g., RC2 = R2.5) of the most adjacent bent portion among the bent portions of the second resistance portion 91-2.

[0070] As described above, the ceramic susceptor 100 of the present invention forms a heating element pattern without a hairpin section in the central portion of the susceptor plate 110 where the embedding density of the heating element 114 is high, thereby improving the temperature uniformity in the entire area of the upper surface of the susceptor and greatly extending the life of the heater pattern.

[0071] As described above, the present invention has been described with specific matters such as specific components, limited embodiments, and drawings, but this is only provided to assist in a more general understanding of the present invention. The present invention is not limited to the above embodiments, and those with ordinary knowledge in the field to which the present invention pertains can make various modifications and deformations without departing from the essential characteristics of the present invention. Therefore, the idea of the present invention should not be defined only by the described embodiments, and not only the scope of the following claims, but also any technical ideas with modifications equivalent or equivalent to this scope of claims should be interpreted as being included in the scope of rights of the present invention.

Explanation of Reference Numerals

[0072] 110 Insulating plate 114 Heating element 71a, 71b, 81a, 81b, 82a, 82b Terminal pairs 85 Arc portion 86 Bending portion 91, 91-1, 91-2 Resistance portions 92, 92-1, 92-2 Connecting portions 910, 910-1, 910-2 Central resistance portions

Claims

1. An insulating plate on which a heating element is disposed, and a shaft joined to the lower part of the insulating plate, comprising the heating element includes a first heating element pattern including a first resistance part and a first connection part connected between a first pair of terminals, A susceptor including a first central resistance part disposed within a diameter region smaller than a joint portion between the insulating plate and the shaft in a plan view of the insulating plate with the first resistance part projected thereon.

2. The first resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bent parts connecting the arc parts, The susceptor according to claim 1, wherein a curve of the first central resistance part is formed to meet an extension line of a virtual straight line passing through a spaced space between adjacent bent parts.

3. The first resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bent parts connecting the arc parts, The susceptor according to claim 1, wherein a curve of the first central resistance part is formed to meet an extension line extended from a bent part closest to the first central resistance part.

4. The susceptor according to claim 1, wherein a curvature radius of a part of the first central resistance part close to any one of the first pair of terminals is formed to be larger than a curvature radius at a bent part of the first resistance part.

5. The susceptor according to claim 4, wherein a curvature radius of a part of the first central resistance part close to any one of the first pair of terminals is at least twice as large as a maximum curvature radius of a bent part of the first resistance part.

6. The susceptor according to claim 1, wherein a curvature radius of a part of the first central resistance part close to any one of the first pair of terminals is formed to be larger than a curvature radius of a bent part closest to the first central resistance part among the bent parts of the first resistance part.

7. The susceptor according to claim 1, wherein the first pair of terminals is disposed within a diameter region smaller than a joint portion between the insulating plate and the shaft.

8. The heating element includes a second heating element pattern including a second resistance part and a second connection part connected between a second pair of terminals, The susceptor according to claim 1, further including a second central resistance part of the second resistance part, wherein in a plan view of the insulating plate with the first resistance part and the second resistance part projected thereon, the first resistance part and the second resistance part are disposed within a diameter region smaller than a joint portion between the insulating plate and the shaft.

9. The second resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bending parts connecting the arc parts to each other. The susceptor according to claim 8, wherein at least one of the curve of the first central resistance part and the curve of the second central resistance part is formed so as to meet an extension line of a virtual straight line passing through a spaced space between adjacent bending parts.

10. The susceptor according to claim 9, wherein the adjacent bending parts include the bending parts of the first resistance part and the bending parts of the second resistance part where the bending parts of the first resistance part and the second resistance part are adjacent to each other.

11. The second resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bending parts connecting the arc parts to each other. The susceptor according to claim 8, wherein at least one of the curve of the first central resistance part and the curve of the second central resistance part is formed so as to meet an extension line of a virtual line extended from the bending part of the first central resistance part that is closest to the first central resistance part or the second central resistance part.

12. The second resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bending parts connecting the arc parts to each other. The susceptor according to claim 8, wherein at least one of the curve of the first central resistance part and the curve of the second central resistance part is formed so as to meet an extension line of a virtual line extended from the bending part of the second central resistance part that is closest to the first central resistance part or the second central resistance part.

13. The second resistance part includes a plurality of arc parts connected in the circumferential direction and a plurality of bending parts connecting the arc parts to each other. The susceptor according to claim 8, wherein at least one of the curve of the first central resistance part and the curve of the second central resistance part is formed so as to meet the respective extension lines of virtual lines extended from the bending part of the first central resistance part and the bending part of the second central resistance part that are closest to the first central resistance part and the second central resistance part, respectively.

14. The susceptor according to claim 8, wherein the curves of the first central resistance part and the second central resistance part are each formed such that the radius of curvature of a part close to any one of the respective terminal pairs is larger than the radius of curvature at the bending parts of the first resistance part and the second resistance part.

15. The susceptor according to claim 14, wherein the radius of curvature of a part close to any one of the respective terminal pairs is at least twice the maximum radius of curvature of the bending parts of the first resistance part and the second resistance part.

16. The curve of the first central resistance portion is formed such that the radius of curvature of a portion close to any one of the first terminal pairs is larger than the radius of curvature of the most adjacent bent portion among the bent portions of the first resistance portion. The susceptor according to claim 8, wherein the curve of the second central resistance portion is formed such that the radius of curvature of a portion close to any one of the second terminal pairs is larger than the radius of curvature of the most adjacent bent portion among the bent portions of the second resistance portion.

17. The susceptor according to claim 8, wherein the second terminal pair is disposed within a diameter region smaller than a joint portion between the insulating plate and the shaft.

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