Ceramic susceptor

Abstract

Provided is a ceramic susceptor comprising an RF / ESC electrode and a terminal rod connected thereto, the ceramic susceptor being capable of effectively preventing an excessive potential difference from being generated locally between a ceramic plate surface and a wafer. The ceramic susceptor comprises: a ceramic plate that has a first surface on which a wafer is placed, and a second surface facing the first surface; an inner electrode that is embedded in the ceramic plate and that is an RF electrode and / or an ESC electrode; a terminal rod that has one end electrically connected to the inner electrode and another end extending from the second surface; and a plurality of protrusions that are disposed on the first surface of the ceramic plate. If the ceramic plate is seen in a perspective plan view in the central axis direction of the ceramic plate, at least one of the protrusions is disposed at a location at least partially overlapping a terminal region defined by an outer periphery of a connecting portion, of the terminal rod, with the inner electrode.

Description

Ceramic Susceptor

[0001] The present disclosure relates to ceramic susceptors.

[0002] In semiconductor manufacturing processes, susceptors are used to support wafers in film deposition and etching equipment. A widely used susceptor includes a ceramic plate on which the wafer is placed and a cylindrical ceramic shaft attached to the ceramic plate. The ceramic plate typically has a ceramic base made of aluminum nitride (AlN) or other material with excellent heat and corrosion resistance, with internal electrodes embedded therein, such as heater electrodes, RF electrodes, and electrostatic chuck (ESC) electrodes.

[0003] A plasma CVD process uses a ceramic susceptor equipped with a ceramic plate in which RF electrodes and / or ESC electrodes (hereinafter collectively referred to as RF / ESC electrodes) and heater electrodes are embedded. FIGS. 15 and 16 schematically show examples of conventional film formation apparatuses 100, 100′ equipped with such a ceramic susceptor 110. The film formation apparatuses 100, 100′ include a chamber 102, a ceramic plate 112 in which an RF / ESC electrode 114 and a heater electrode 120 are embedded, and a plasma upper electrode 104. A wafer W is placed on the ceramic plate 112, and a ceramic shaft 124 is provided on the backside of the ceramic plate 112. In the film formation apparatus 100 shown in FIG. 15, the plasma upper electrode 104 is connected to an RF / ESC power supply 106, and the RF / ESC electrode 114 is connected to ground 108 via an RF / ESC terminal rod 116. In this configuration, RF is applied from the plasma upper electrode 104 to generate plasma, as represented by the arrows in Fig. 15, and RF current flows to ground 108 through the RF / ESC terminal rod 116. In a film formation apparatus 100' shown in Fig. 16, the plasma upper electrode 104 is connected to ground 108, while the RF / ESC electrode 114 is connected to the RF / ESC power supply 106 via the RF / ESC terminal rod 116. In this configuration, RF is applied from the RF / ESC electrode 114 to generate plasma, as represented by the arrows in Fig. 16, and RF / ESC current flows from the RF / ESC electrode 114 to the plasma upper electrode 104 via the RF / ESC terminal rod 116.

[0004] As an example of a ceramic susceptor equipped with an RF rod, Patent Document 1 (Japanese Patent No. 7129587) discloses a wafer support base that includes a ceramic base in which an RF electrode and a heater electrode are embedded, a hole that is provided from one surface of the ceramic base toward the RF electrode, and an RF rod that is bonded to the RF electrode exposed at the bottom of the hole.

[0005] On the other hand, susceptors having a plurality of embossed protrusions on their surface are known. For example, Patent Document 2 (Japanese Patent No. 6948458) discloses a Johnson-Rahbek electrostatic chuck heater used to form a conductive film on a wafer. This electrostatic chuck heater includes a disk-shaped ceramic base equipped with an electrostatic electrode and a resistance heating element, and a hollow shaft attached to the ceramic base. The surface of the ceramic base is provided with a plurality of embossed protrusions and convex portions in predetermined regions that can contact the wafer. It is said that these protrusions and convex portions (hereinafter collectively referred to as protrusions) enable stable chucking of the wafer.

[0006] Patent No. 7129587 Patent No. 6948458

[0007] In a plasma CVD process, a film may be formed by applying a voltage to the RF / ESC electrode and adsorbing a wafer onto the surface (particularly the protrusions) of the ceramic plate. At this time, as conceptually shown in FIG. 17 , even within the same plane of the RF / ESC electrode 114, a large amount of charge is supplied, particularly to the portion directly above the RF / ESC terminal rod 116. Directly above the RF / ESC terminal rod 116, a space is typically formed between the ceramic plate 112 and the wafer W via a plurality of protrusions 118 arranged on the ceramic plate 112. In such a conventional configuration, charge may concentrate on the surface of the ceramic plate 112 and the wafer W directly above the RF / ESC terminal rod 116, potentially creating a localized excessive potential difference between them. Such an excessive potential difference can cause arcing and should be avoided.

[0008] The present inventors have now discovered that in a ceramic susceptor equipped with an RF / ESC electrode and a terminal rod connected thereto, by arranging at least one protrusion at a predetermined position when viewed from above, it is possible to effectively prevent excessive local potential differences from occurring between the ceramic plate surface and the wafer.

[0009] Therefore, an object of the present invention is to provide a ceramic susceptor having an RF / ESC electrode and a terminal rod connected thereto, which can effectively prevent an excessive local potential difference from occurring between the ceramic plate surface and the wafer.

[0010] The present disclosure provides the following aspects. [Aspect 1] A ceramic susceptor comprising: a ceramic plate having a first surface on which a wafer is placed and a second surface opposite the first surface; an internal electrode which is an RF electrode and / or an ESC electrode embedded in the ceramic plate; a terminal rod having one end electrically connected to the internal electrode and the other end extending from the second surface; and a plurality of protrusions arranged on the first surface of the ceramic plate, wherein, when the ceramic plate is viewed from above in a perspective direction of the central axis of the ceramic plate, at least one of the protrusions is arranged at a position at least partially overlapping with a terminal region defined by the outer periphery of a connection portion of the terminal rod with the internal electrode. [Aspect 2] The ceramic susceptor according to Aspect 1, wherein the protrusions are cylindrical or polygonal prism-shaped. [Aspect 3] Each of the protrusions has a length of 0.19 mm or less when the ceramic plate is viewed from above in the central axis direction. ２ A ceramic susceptor according to any one of Aspects 1 to 3, wherein the projections have a height of 1 to 500 μm. A ceramic susceptor according to Aspect 4, wherein the projections have a height of 1 to 500 μm. A ceramic susceptor according to Aspect 5, wherein the connecting portion of the terminal rod with the internal electrode has an area of ​​3.00 to 80.0 mm in a plane perpendicular to the central axis. ２ A ceramic susceptor according to any one of Aspects 1 to 4, wherein the ceramic susceptor has a cross-sectional area of ​​0.5 to 3.0 mm. [Aspect 6] A ceramic susceptor according to any one of Aspects 1 to 5, wherein the separation distance between the upper surface of the protrusion and the internal electrode in the central axis direction is 0.5 to 3.0 mm. [Aspect 7] When the ceramic plate is seen through a plan view in the thickness direction, the overlapping area between the at least one protrusion and the terminal region is 0.36 mm. ２The ceramic susceptor according to any one of Aspects 1 to 6, wherein the at least one protrusion is disposed at a position that is completely contained within the terminal region when the ceramic plate is seen through a plan view in the thickness direction. [Aspect 9] The ceramic susceptor according to any one of Aspects 1 to 8, further comprising a heater electrode embedded in the ceramic plate at a depth different from that of the internal electrode. [Aspect 10] The ceramic susceptor according to any one of Aspects 1 to 9, further comprising a heater rod having one end electrically connected to the heater electrode and the other end extending from the second surface. [Aspect 11] The ceramic susceptor according to any one of Aspects 1 to 10, further comprising a cylindrical ceramic shaft attached to the second surface and having an internal space.

[0011] 1 is a schematic top view showing an example of a ceramic susceptor according to the present disclosure. FIG. 1 is a cross-sectional view taken along line A-A of the ceramic susceptor shown in FIG. 1. FIG. 2 is a schematic cross-sectional view conceptually showing the distribution of charges and electrons in the ceramic susceptor of the present disclosure. FIG. 3 is a schematic plan view showing an example of the positional relationship between the connection portion of a terminal rod and the protrusion of a ceramic plate in the ceramic susceptor of the present disclosure. FIG. 4 is a cross-sectional view taken along line B-B of the ceramic susceptor shown in FIG. 4. FIG. 5 is a schematic plan view showing another example of the positional relationship between the connection portion of a terminal rod and the protrusion of a ceramic plate in the ceramic susceptor of the present disclosure. FIG. 6 is a cross-sectional view taken along line C-C of the ceramic susceptor shown in FIG. 6. FIG. 7 is a schematic plan view showing an example of a test piece produced in Examples 1 and 2. FIG. 8 is a schematic side view of the test piece shown in FIG. 9. FIG. 9 is a back view of the test piece shown in FIG. 9. FIG. 10 is a schematic configuration diagram showing a measurement system using the test piece shown in FIG. 9. FIG. 11 is a plan perspective view showing an example in which the connection portion of a terminal rod and the protrusion of a ceramic plate completely overlap. FIG. 12 is a plan perspective view showing an example in which the connection portion of a terminal rod and the protrusion of a ceramic plate partially overlap. 1 is a plan view perspective view showing an example in which a connection portion of a terminal rod and a protrusion of a ceramic plate do not overlap. 2 is a schematic cross-sectional view showing an example of a conventional film formation apparatus. 3 is a schematic cross-sectional view showing another example of a conventional film formation apparatus. 4 is a schematic cross-sectional view conceptually showing the distribution of charges and electrons in a conventional ceramic susceptor.

[0012] The ceramic susceptor according to the present invention is a ceramic platform for supporting a wafer in a semiconductor manufacturing apparatus. For example, the ceramic susceptor according to the present invention may be a ceramic heater for a semiconductor film formation apparatus or an electrostatic chuck for a semiconductor etching apparatus. Typical examples of film formation apparatuses include CVD (chemical vapor deposition) apparatuses (e.g., thermal CVD apparatuses, plasma CVD apparatuses, photo-CVD apparatuses, and MOCVD apparatuses) and PVD (physical vapor deposition) apparatuses, with plasma CVD apparatuses being particularly preferred.

[0013] 1 to 5 show an example of a ceramic susceptor 10. The ceramic susceptor 10 includes a ceramic plate 12, an internal electrode 14, a terminal rod 16, and a plurality of protrusions 18. The ceramic plate 12 has a first surface 12a on which a wafer W is placed and a second surface 12b opposite the first surface 12a. The internal electrode 14 is an RF electrode and / or an ESC electrode (i.e., an RF / ESC electrode) and is embedded in the ceramic plate 12. One end of the terminal rod 16 is electrically connected to the internal electrode 14, and the other end extends from the second surface 12b. A plurality of protrusions 18 are disposed on the first surface 12a of the ceramic plate 12. At least one protrusion 18 is disposed at a position at least partially overlapping a terminal region defined by the outer periphery of a connection portion 16a of the terminal rod 16 with the internal electrode 14, when the ceramic plate 12 is viewed from above in the direction of its central axis C. In a ceramic susceptor having an internal electrode 14 (RF / ESC electrode) and a terminal rod 16 connected thereto, when viewed from above, by arranging at least one protrusion 18 at a predetermined position, it is possible to effectively prevent excessive local potential differences from occurring between the ceramic plate surface and the wafer W.

[0014] That is, as described above, in a plasma CVD process, film formation can be performed in a state in which a voltage is applied to the RF / ESC electrode to electrostatically attract a wafer to the surface (particularly the protrusions) of the ceramic plate. At this time, as conceptually shown in FIG. 17 , even within the same plane of the RF / ESC electrode 114, a large amount of charge is supplied, particularly to the portion directly above the RF / ESC terminal rod 116. Directly above the RF / ESC terminal rod 116, a space is typically formed between the ceramic plate 112 and the wafer W via a plurality of protrusions 118 arranged on the ceramic plate 112. In such a conventional configuration, charge concentrates on the surface of the ceramic plate 112 and the wafer W directly above the RF / ESC terminal rod 116, potentially creating a localized excessive potential difference between them. Such an excessive potential difference can cause arcing. Arcing can damage the ceramic plate 12, so it is desirable to avoid it. In this regard, in the present invention, as conceptually shown in Fig. 3, by arranging protrusions 18 on the first surface 12a of the ceramic plate 12 directly above the terminal rods 16, it is possible to actively pass current between the protrusions 18 and the wafer W. In other words, it is possible to actively release electric charge from the protrusions 18 directly above the terminal rods 16 to the wafer W. In this way, it is possible to effectively prevent excessive local potential differences from occurring between the surface of the ceramic plate 12 and the wafer W.

[0015] The ceramic plate 12 preferably contains aluminum nitride and / or aluminum oxide, more preferably aluminum nitride, in its main portion (i.e., the ceramic substrate) other than the embedded members such as the internal electrode 14 and the heater electrode 20, from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

[0016] The ceramic plate 12 is disk-shaped. However, the planar shape of the disk-shaped ceramic plate 12 does not need to be a perfect circle; for example, it may be an incomplete circle with a portion missing, such as an orientation flat. The size of the ceramic plate 12 is not particularly limited and can be determined appropriately depending on the diameter of the wafer to be used. However, when the ceramic plate 12 is circular, the diameter is typically 150 to 450 mm, and particularly for 300 mm silicon wafers, the diameter is typically 320 to 380 mm. The thickness of the ceramic plate 12 is typically 10 to 25 mm.

[0017] The internal electrode 14 is an RF electrode and / or an ESC electrode embedded in the ceramic plate 12. When a high frequency is applied to the RF electrode, film formation by a plasma CVD process is possible. The ESC electrode is an abbreviation for an electrostatic chuck (ESC) electrode and is also called an electrostatic electrode. When a voltage is applied to the ESC electrode from an external power source, the ESC electrode chucks a wafer placed on the first surface 12a of the ceramic plate 12 by the Johnsen-Rahbek force. The ESC electrode is preferably a circular thin-layer electrode with a diameter slightly smaller than that of the ceramic plate 12. For example, it may be a mesh electrode formed by weaving thin metal wires into a net shape into a sheet. The ESC electrode may also be used as a plasma electrode. That is, by applying a high frequency to the ESC electrode, the ESC electrode can also be used as an RF electrode, and film formation by a plasma CVD process can also be performed.

[0018] The internal electrode 14 can be embedded at any depth in the ceramic plate 12. In this regard, the distance between the upper surfaces of the projections 18 and the internal electrode 14 in the direction of the central axis C (i.e., the depth position of the internal electrode 14 with respect to the upper surfaces of the projections 18) is preferably 0.5 to 3.0 mm, and more preferably 0.5 to 2.0 mm. Within these ranges, the internal electrode 14 can effectively function as an RF electrode and / or an ESC electrode.

[0019] A terminal rod 16 for power supply is connected to the internal electrode 14, and the internal electrode 14 can be connected to an external power source (not shown) via the terminal rod 16. The terminal rod 16 is not particularly limited as long as it is a rod-shaped member that functions as a terminal as a whole. The terminal itself may be rod-shaped, or it may be a composite member in which a rod-shaped member is connected to a non-rod-shaped terminal, or a composite member in which a rod-shaped member is connected to a rod-shaped terminal. Furthermore, as shown in FIGS. 5 and 7 , the connection portion 16a of the terminal rod 16 with the internal electrode 14 may have a smaller cross-sectional area (e.g., a smaller diameter) than the other main portions. The cross-sectional area of ​​the connection portion 16a of the terminal rod 16 in a plane perpendicular to the central axis C is 3.00 to 80.0 mm ２ Preferably, the thickness is 3.0 to 30.0 mm. ２ , more preferably 5.0 to 10.0 mm ２ If the cross-sectional area is within these ranges, sufficient connection strength can be obtained while effectively alleviating internal stress.

[0020] The protrusions 18 are for contacting the rear surface of the wafer W to support the wafer W, and a plurality of protrusions 18 are arranged on the first surface 12a of the ceramic plate 12. The shape of each protrusion 18 is not particularly limited, and may be cylindrical or polygonal prism (e.g., square prism, pentagonal prism, hexagonal prism, etc.). When the ceramic plate 12 is viewed in a plane in the direction of the central axis C, the area of ​​each of the protrusions 18 (i.e., the upper surface area) is 0.19 mm ２ It is preferably 0.19 to 80.0 mm or more, and more preferably 0.19 to 80.0 mm ２ , and more preferably 0.38 to 20.0 mm ２ The protrusions 18 are preferably integrally formed with the ceramic plate 12 by embossing or the like. Therefore, like the ceramic plate 12, the protrusions 18 preferably contain aluminum nitride and / or aluminum oxide, more preferably aluminum nitride. The height of the protrusions 18 is not particularly limited, but is preferably 1 to 500 μm, more preferably 1 to 350 μm.

[0021] The plurality of protrusions 18 are preferably arranged according to any regular pattern. For example, as shown in FIG. 1 , they may be arranged according to a regular radial pattern. Alternatively, they may be arranged according to (or to form) a regular pattern having a constituent unit selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon. That is, the centers of the plurality of protrusions 18 may be arranged so as to be located on a virtual line (e.g., a vertex in the case of a polygon) that forms a regular pattern in which a plurality of the above constituent units are repeated. In other words, a virtual figure drawn by connecting the centers of adjacent protrusions 18 may form a regular pattern having a constituent unit selected from the group consisting of a circle, a square, an equilateral triangle, and a regular hexagon.

[0022] As described above, at least one protrusion 18 is arranged at a position at which it at least partially overlaps with the terminal area defined by the outer periphery of the connection portion 16a when the ceramic plate 12 is viewed in a plan view in the direction of its central axis C. Therefore, the at least one protrusion 18 may be arranged at a position where it is completely contained within the terminal area (connection portion 16a) (when the ceramic plate 12 is viewed in a plan view in the thickness direction) as shown in Figures 4 and 5, or may be arranged at a position where only a portion of the at least one protrusion 18 overlaps with the terminal area (connection portion 16a) as shown in Figures 6 and 7. In the latter case, when the ceramic plate 12 is viewed in a plan view in the thickness direction, the overlapping area between the at least one protrusion 18 and the terminal area (connection portion 16a) is 0.36 mm ２ It is preferably 0.76 mm or more, and more preferably 0.76 mm ２ More preferably, 0.79 mm ２ The upper limit of the overlapping area between at least one projection 18 and the terminal area (connection portion 16a) is not particularly limited, but is typically 80 mm ２ less than or equal to 20 mm, more typically ２Such an overlap of a predetermined area or more can more effectively prevent excessive localized potential differences from occurring between the surface of the ceramic plate 12 and the wafer W. Since it is most preferable that the protrusions 18 be disposed at positions that are completely contained within the terminal regions (connection portions 16 a), the upper limit of the overlapping area can be the area of ​​the top surfaces of the protrusions 18.

[0023] Preferably, the heater electrode 20 is embedded in the ceramic plate 12 at a different depth from the internal electrode 14. The heater electrode 20 is not particularly limited, but may be, for example, a conductive coil wired in a single stroke across the entire surface of the ceramic plate 12. The single-stroke shape may be various known shapes, such as a spiral shape or an alternating forward and backward stroke. Heater rods 22 are connected to both ends of the heater electrode 20 for power supply, and the heater rods 22 are connected to a heater power supply (not shown) via the internal space S of the ceramic shaft 24. Each heater rod 22 may be configured such that one end is electrically connected to the heater electrode 20 and the other end extends from the second surface 12b. When power is supplied from the heater power supply, the heater electrode 20 generates heat to heat the wafer W placed on the first surface 12a. The heater electrode 20 is not limited to a coil and may be, for example, a ribbon (a thin, elongated plate) or a mesh.

[0024] The ceramic shaft 24 is a cylindrical shaft attached to the second surface 12b of the ceramic plate 12 and may have a configuration similar to that of ceramic shafts used in known ceramic susceptors or ceramic heaters. The internal space S is configured to allow elongated members such as the terminal rod 16 and heater rod 22 to pass therethrough. The ceramic shaft 24 is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the ceramic shaft 24 preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride. The upper end surface of the ceramic shaft 24 is preferably joined to the second surface 12b of the ceramic plate 12 by solid-state bonding or diffusion bonding. The outer diameter of the ceramic shaft 24 is not particularly limited, but is preferably 40 to 60 mm. The inner diameter of the ceramic shaft 24 (the diameter of the internal space S) is also not particularly limited, but is preferably 33 to 55 mm.

[0025] The present invention will be explained in more detail by the following examples, but the present invention is not limited to the following examples.

[0026] Examples 1 to 9 (1) Preparation of Test Pieces Ten test pieces 10' having the structure shown in Figures 8 to 10 or modified structures thereof were prepared for each example by a known method. These test pieces 10' have a basic configuration that mimics the ceramic susceptor 10 of the present disclosure, but the diameter of the projections 18 and the minimum separation distance and positional relationship between the projections 18 and the connection portions 16a of the terminal rods 16 were changed according to each example, as shown in Table 1 (and Figures 12 to 14 referred to therein). The components and specifications of the test pieces 10' are as follows:

[0027] <Constituent members and their specifications> Ceramic plate 12: disc-shaped aluminum nitride sintered body (diameter: 50 mm, thickness: 20 mm, with internal electrode 14 and terminal rod 16 embedded inside) Protrusions 18: seven columnar protrusions (diameter: value shown in Table 1, height: 50 μm) made of aluminum nitride sintered body formed on the first surface 12 a of the ceramic plate 12. Six of the protrusions 18 are arranged at equal intervals around the outer periphery of the first surface 12 a along a circumference with a pitch circle diameter (PCD) of 39 mm, and the remaining one protrusion 18 is arranged at or near the center of the first surface 12 a so as to satisfy the positional relationship shown in Table 1. Internal electrode 14 (RF / ESC electrode): a molybdenum mesh (diameter: 40 mm) embedded in ceramic plate 12 at a depth of 1 mm from the top surface of protrusion 18. Terminal rod 16 (RF / ESC terminal rod): a nickel rod inserted into a terminal hole formed in second surface 12 b of ceramic plate 12 and joined to internal electrode 14 (diameter of connecting portion 16 a with internal electrode 14: 3 mm, diameter of other main portions: 5 mm).

[0028] (2) Evaluation As shown in FIG. 11 , a stainless steel plate was placed as a metal electrode 30 on the seven protrusions 18 of the test piece 10′, and the metal electrode 30 and the lower end of the terminal rod 16 were each connected to a power supply 32. A voltage of 1 kV was applied between the metal electrode 30 and the terminal rod 16, and the occurrence of an excessive potential difference directly above the connection portion 16a of the terminal rod 16 was determined by the occurrence of arcing. The number of test pieces in which arcing occurred was counted among the 10 test pieces. The results were applied to the following criteria to rank and evaluate the effectiveness of preventing localized excessive potential differences between the ceramic plate surface and the wafer. <Evaluation Criteria> - Rating A: No arcing occurred in any of the 10 test pieces. In other words, the effectiveness of preventing excessive potential differences was particularly excellent. - Rating B: Arcing occurred in one or two of the 10 test pieces. In other words, the effectiveness of preventing excessive potential differences was good. Evaluation C: Arcing occurred in 3 or more of the 10 test pieces, meaning that the effect of preventing an excessive potential difference was poor.

[0029]

[0030] 10, 110 Ceramic susceptor 12, 112 Ceramic plate 12a First surface 12b Second surface 14 Internal electrode 16 Terminal rod 16a Connection portion 18 Protrusion 20, 120 Heater electrode 22 Heater rod 24, 124 Ceramic shaft 100, 100' Film formation apparatus 102 Chamber 104 Plasma upper electrode 106 RF / ESC power supply 108 Ground 114 RF / ESC electrode 120 RF rod S Internal space W Wafer

Claims

1. A ceramic plate having a first surface on which a wafer is placed and a second surface facing the first surface, An internal electrode, which is an RF electrode and / or an ESC electrode, is embedded in the ceramic plate. A terminal rod having one end electrically connected to the internal electrode and the other end extending from the second surface, Multiple protrusions arranged on the first surface of the ceramic plate, A ceramic susceptor equipped with, When the ceramic plate is viewed planarly in the direction of its central axis, at least one of the protrusions is positioned to at least partially overlap with the terminal region defined by the outer circumference of the connection portion of the terminal rod with the internal electrode. Each of the aforementioned protrusions has an area of ​​0.38 mm² or more when the ceramic plate is viewed in plan along the central axis direction. The aforementioned protrusion has a height of 1 to 500 μm, The connection portion of the terminal rod with the internal electrode has a cross-sectional area of ​​3.00 to 80.0 mm² in a plane perpendicular to the central axis. The distance between the upper surface of the projection and the internal electrode in the central axis direction is 0.5 to 3.0 mm. A ceramic susceptor in which, when the ceramic plate is viewed planar in the thickness direction, the overlapping area between the at least one protrusion and the terminal region is 0.36 mm² or more.

2. The ceramic susceptor according to claim 1, wherein the projection is cylindrical or polygonal prismatic.

3. The ceramic susceptor according to claim 1 or 2, wherein the at least one projection is positioned so as to fit completely within the terminal region when the ceramic plate is viewed planarly in the thickness direction.

4. The ceramic susceptor according to claim 1 or 2, further comprising a heater electrode embedded in the ceramic plate at a depth different from that of the internal electrode.

5. The ceramic susceptor according to claim 4, further comprising a heater rod having one end electrically connected to the heater electrode and the other end extending from the second surface.

6. The ceramic susceptor according to claim 1 or 2, further comprising a cylindrical ceramic shaft attached to the second surface and having an internal space.