Susceptor

Abstract

Provided is a susceptor capable of stably holding a wafer. This susceptor comprises a plate-shaped ceramic plate having a first main surface and a second main surface. The ceramic plate has, on the first main surface thereof, a first support wall that extends along a circumferential direction of the ceramic plate. A wafer is placed on the first support wall. An electrostatic chuck electrode for chucking the wafer by means of an electrostatic force is incorporated into the ceramic plate. The electrostatic chuck electrode includes: a positive electrode to which a positive voltage is applied; and a negative electrode to which a negative voltage is applied. The positive electrode includes a first positive electrode part that, when viewed from a direction perpendicular to the first main surface, overlaps a portion of an annular region where the first support wall is provided at the first main surface. The negative electrode includes a first negative electrode part that, when viewed from a direction perpendicular to the first main surface, overlaps a portion of the annular region. Pluralities of the first positive electrode part and pluralities of the first negative electrode part are alternately disposed multiple times in the circumferential direction of the ceramic plate.

Description

Susceptor

[0001] This disclosure relates to a susceptor. This application claims priority based on Japanese Patent Application No. 2024-193518 filed on November 5, 2024, and incorporates all the descriptions described in the Japanese patent application.

[0002] In a semiconductor manufacturing apparatus, a susceptor is used as a stage for supporting a wafer when performing processes such as film formation and etching on the wafer. The susceptor includes a plate-shaped ceramic plate having a wafer support surface for supporting the wafer on one main surface. Some susceptors are provided with a support wall formed by an annular protrusion on the wafer support surface. When the wafer is placed on the support wall, a space surrounded by the support wall is formed between the wafer and the ceramic plate. A gas, for example, for efficiently performing heat conduction of the wafer and the ceramic plate is supplied to this space.

[0003] For example, in the process of forming a semiconductor thin film, it is necessary to hold the wafer so as not to move on the wafer support surface. Therefore, the susceptor is required to have an electrostatic adsorption function for adsorbing the wafer to the wafer support surface by electrostatic force. As the method of electrostatic adsorption, there are a monopole method in which an electrostatic chuck electrode for generating an adsorption force is built into the ceramic plate on the wafer support surface, and a bipolar method in which two types of electrostatic chuck electrodes, a positive electrode and a negative electrode, are built into the ceramic plate in a state of being separated from each other.

[0004] In the bipolar method, an adsorption force is generated by applying a voltage between the positive electrode and the negative electrode. Referring to FIG. 14, the positive electrode 100 and the negative electrode 101 are formed, for example, in a semicircular shape (see, for example, Patent Document 1).

[0005] Japanese Unexamined Patent Application Publication No. 2005-294648

[0006] In a bipolar system, if there is an electrical polarity difference between the portion of the ceramic plate where the positive electrode is embedded and the portion where the negative electrode is embedded, a difference will occur in the suction force generated in the region where the positive electrode is embedded and the suction force generated in the region where the negative electrode is embedded on the wafer support surface. As a result, there will be regions on the wafer support surface where the wafer suction force is strong and regions where the wafer suction force is weak. In a ceramic plate provided with a support wall, the support wall is the part that comes into direct contact with the wafer as the wafer is placed on it. Therefore, the suction force generated on the support wall is particularly important as it greatly affects the suction of the wafer. However, when a semicircular positive electrode 100 and a negative electrode 101 as shown in Figure 14 are embedded in the ceramic plate 102, the support wall 103 is divided into a portion 104 with high suction force and a portion 105 with low suction force. As a result, there is a risk that the wafer suction by the support wall 103 will be uneven, and the wafer may not be able to be stably held on the wafer support surface.

[0007] To stably hold a wafer on a wafer support surface, it is necessary to suppress the unevenness of the suction force generated on the support wall on which the wafer is placed. One of the objectives of this disclosure is to provide a susceptor that can stably hold a wafer on a wafer support surface.

[0008] A susceptor according to the present disclosure comprises a plate-shaped ceramic plate having a first principal surface and a second principal surface, which are a pair of principal surfaces spaced apart in the thickness direction. In a susceptor according to a first aspect of the present disclosure, the ceramic plate is provided with a first support wall extending along the circumferential direction of the ceramic plate on the first principal surface. A wafer is placed on the first support wall. The ceramic plate also incorporates an electrostatic chuck electrode for adsorbing the wafer by electrostatic force. The electrostatic chuck electrode comprises a positive electrode to which a positive voltage is applied and a negative electrode to which a negative voltage is applied. The positive electrode includes a first positive electrode portion that overlaps with a portion of the annular region on the first principal surface where the first support wall is provided, when viewed from a direction perpendicular to the first principal surface. The negative electrode includes a first negative electrode portion that overlaps with a portion of the annular region, when viewed from a direction perpendicular to the first principal surface. Multiple first positive electrode portions and multiple first negative electrode portions are arranged alternately in multiples in the circumferential direction of the ceramic plate.

[0009] According to this disclosure, a susceptor is provided that can stably hold a wafer on a first main surface that supports the wafer in a ceramic plate.

[0010] Figure 1 is a plan view of a susceptor according to one embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view of the susceptor shown in Figure 1, cut by a vertical plane including the line A-A in Figure 1. Figure 3 is a schematic cross-sectional view of a modified example of the susceptor according to the present disclosure. Figure 4 is a plan view of a modified example of the susceptor according to the present disclosure. Figure 5 is a schematic cross-sectional view of the susceptor shown in Figure 4, cut by a vertical plane including the line A-A in Figure 4. Figure 6 shows the electrode shapes of a first example of positive and negative electrodes embedded in the ceramic plate of the susceptor shown in Figure 1. Figure 7 shows the electrode shapes of a second example of positive and negative electrodes embedded in the ceramic plate of the susceptor shown in Figure 1. Figure 8 shows the electrode shapes of a third example of positive and negative electrodes embedded in the ceramic plate of the susceptor shown in Figure 1. Figure 9 shows the electrode shapes of a fourth example of positive and negative electrodes embedded in the ceramic plate of the susceptor shown in Figure 1. Figure 10 is a plan view of a modified susceptor according to the present disclosure. Figure 11 is a schematic cross-sectional view of the susceptor shown in Figure 10, cut by a vertical plane including line A-A in Figure 10. Figure 12 is a plan view of a modified susceptor according to the present disclosure. Figure 13 is a diagram showing the electrode shapes of the positive and negative electrodes embedded in the ceramic plate of the susceptor shown in Figure 12. Figure 14 is a diagram showing the electrode shapes of a conventional example of the positive and negative electrodes embedded in the ceramic plate of the susceptor.

[0011] [Summary of Embodiments] First, embodiments of a susceptor in accordance with this disclosure will be listed and described.

[0012] A susceptor according to a first aspect of this disclosure comprises a plate-shaped ceramic plate having a first main surface and a second main surface, which are a pair of main surfaces spaced apart in the thickness direction. In the susceptor according to the first aspect, the ceramic plate is provided with a first support wall extending along the circumferential direction of the ceramic plate on the first main surface. A wafer is placed on the first support wall. The ceramic plate also incorporates an electrostatic chuck electrode for adsorbing the wafer by electrostatic force. The electrostatic chuck electrode comprises a positive electrode to which a positive voltage is applied and a negative electrode to which a negative voltage is applied. The positive electrode includes a first positive electrode portion that overlaps with a portion of the annular region on the first main surface where the first support wall is provided, when viewed from a direction perpendicular to the first main surface. The negative electrode includes a first negative electrode portion that overlaps with a portion of the annular region, when viewed from a direction perpendicular to the first main surface. Multiple first positive electrode portions and first negative electrode portions are arranged alternately in the circumferential direction of the ceramic plate.

[0013] According to the susceptor of the first embodiment, a plurality of first positive electrode portions and a plurality of first negative electrode portions are alternately arranged in the circumferential direction of the ceramic plate below the first support wall on which the wafer is placed inside the ceramic plate. "Below" refers to the direction from the first main surface to the second main surface in the thickness direction of the ceramic plate. Therefore, when a voltage is applied between the positive and negative electrodes, portions with high adsorption force and portions with low adsorption force are alternately and evenly generated on the first support wall. Thus, according to the susceptor of the first embodiment, bias in the adsorption of the wafer by the first support wall is suppressed, and the wafer can be stably held on the first main surface.

[0014] As a susceptor according to a second aspect of the present disclosure, the susceptor according to the first aspect may be configured such that the electrostatic chuck electrode comprises one positive electrode and one negative electrode, the positive electrode includes a plurality of first positive electrode portions arranged at intervals in the circumferential direction of a ceramic plate and a second positive electrode portion connected to the plurality of first positive electrode portions and to which a power supply terminal for the positive electrode is electrically connected, and the negative electrode includes a plurality of first negative electrode portions arranged at intervals in the circumferential direction of a ceramic plate and a second negative electrode portion connected to the plurality of first negative electrode portions and to which a power supply terminal for the negative electrode is electrically connected.

[0015] According to the second embodiment of the susceptor, the ceramic plate contains only one positive electrode and one negative electrode as electrostatic chuck electrodes, and by devising the electrode shapes of the positive and negative electrodes, multiple first positive electrode portions and multiple first negative electrode portions are alternately arranged in the circumferential direction of the ceramic plate below the first support wall. Therefore, since only one power supply terminal for the positive electrode and one power supply terminal for the negative electrode need to be provided on the ceramic plate, the structure of the ceramic plate can be simplified according to the second embodiment of the susceptor. Furthermore, for example, when a resistance heating element is incorporated into the ceramic plate, the resistance heating element needs to be positioned to avoid the power supply terminals. However, when multiple positive electrodes and multiple negative electrodes are incorporated into the ceramic plate, it becomes necessary to provide multiple power supply terminals for the positive electrode and multiple power supply terminals for the negative electrode on the ceramic plate, and as a result, many cool spots are formed on the ceramic plate as the resistance heating element avoids the power supply terminals. When many cool spots are formed on the ceramic plate, temperature unevenness is likely to occur on the ceramic plate when the ceramic plate is heated by the resistance heating element, affecting the uniformity of the heating of the ceramic plate. In contrast, according to the second embodiment of the susceptor, only one positive electrode and one negative electrode are embedded in the ceramic plate, and the ceramic plate is provided with only one power supply terminal for the positive electrode and one power supply terminal for the negative electrode, thus reducing the number of cool spots that occur on the ceramic plate. Therefore, according to the second embodiment of the susceptor, the uniformity of the heat distribution of the ceramic plate can be improved.

[0016] As a susceptor according to a third aspect of the present disclosure, the susceptor according to the second aspect may be configured such that, when viewed from a direction perpendicular to the first main surface, the second positive electrode portion and the second negative electrode portion are located in the center of the ceramic plate, and one of the first positive electrode portion and the first negative electrode portion extends from the outer edge of the ceramic plate toward the center, while the other of the first positive electrode portion and the first negative electrode portion extends from the center of the ceramic plate toward the outer edge.

[0017] In the susceptor according to the third embodiment, multiple first positive electrode portions and multiple first negative electrode portions are alternately arranged in the circumferential direction of the ceramic plate, not only below the first support wall but also inside the first support wall. Therefore, when a voltage is applied between the positive and negative electrodes, portions with high adsorption force and portions with low adsorption force alternately and in a balanced manner across almost the entire first main surface. Thus, in the susceptor according to the third embodiment, bias in the adsorption of the wafer by the first main surface is suppressed, and the wafer can be held more stably by the first main surface.

[0018] As a susceptor according to a fourth aspect of this disclosure, the susceptor according to the second aspect may be configured such that, when viewed from a direction perpendicular to the first main surface, the second positive electrode portion and the second negative electrode portion are located in the center of the ceramic plate, the positive electrode includes a plurality of third positive electrode portions that are spaced apart in the circumferential direction of the ceramic plate between a plurality of first positive electrode portions and second positive electrode portions and connected to the plurality of first positive electrode portions and second positive electrode portions, and the negative electrode includes a plurality of third negative electrode portions that are alternately arranged with the third positive electrode portions in the circumferential direction of the ceramic plate between a plurality of first negative electrode portions and second negative electrode portions and connected to the plurality of first negative electrode portions and second negative electrode portions.

[0019] According to the susceptor of the fourth embodiment, multiple third positive electrode portions and multiple third negative electrode portions are alternately arranged in the circumferential direction of the ceramic plate, not only below the first support wall but also inside the first support wall. Therefore, when a voltage is applied between the positive and negative electrodes, portions with high adsorption force and portions with low adsorption force alternately and in a balanced manner are generated across almost the entire surface of the first main surface. Thus, according to the susceptor of the fourth embodiment, bias in the adsorption of the wafer by the first main surface is suppressed, and the wafer can be held more stably by the first main surface.

[0020] As a susceptor relating to the fifth aspect of this disclosure, a susceptor relating to any one of the first to fourth aspects may be configured to incorporate a resistance heating element that generates heat when an electric current is passed through a ceramic plate.

[0021] According to the susceptor of the fifth embodiment, the ceramic plate can be heated by a resistance heating element, and the wafer can be heated via the first main surface. In this case, since the wafer is adsorbed by the first main surface in a state where the unevenness of the adsorption force is suppressed, the wafer can be heated uniformly.

[0022] As a susceptor according to the sixth aspect of the present disclosure, a susceptor according to any one aspect of the first to fifth aspects may be provided on the ceramic plate with a plurality of support protrusions and at least one of at least one second support wall extending along the circumferential direction of the ceramic plate in a region surrounded by a first support wall on the first main surface, and the tips of the support protrusions and the tips of the second support walls may be positioned at the same height as the tips of the first support walls in the thickness direction of the ceramic plate.

[0023] In the susceptor according to the sixth embodiment, the wafer is supported on the first main surface not only by being placed on the first support wall, but also by being placed on at least one of the multiple support protrusions and the second support wall. Therefore, in the susceptor according to the sixth embodiment, the wafer is stably supported by the first main surface. Furthermore, if multiple first positive electrode portions and multiple first negative electrode portions or multiple third positive electrode portions and multiple third negative electrode portions are alternately arranged in the circumferential direction of the ceramic plate inside the first support wall, and if portions with high adsorption force and portions with low adsorption force are alternately and balanced over approximately the entire first main surface, then bias in the adsorption of the wafer by at least one of the multiple support protrusions and the second support wall is suppressed. Therefore, the wafer can be stably held on the first main surface.

[0024] As a susceptor according to the seventh aspect of this disclosure, the susceptor according to the sixth aspect may be configured such that the ratio of the first support wall to the total area of ​​the portion of the ceramic plate in contact with the wafer is 40% or more.

[0025] According to the susceptor of the seventh embodiment, the wafer supported on the first main surface is in contact with the first support wall, a plurality of support protrusions, and at least one of the second support wall, but the wafer can be held more stably on the first main surface because the first support wall is mainly in contact with the wafer.

[0026] As a susceptor according to the eighth aspect of this disclosure, a susceptor according to any one aspect of the first to seventh aspects may be configured such that the first support wall is formed in an annular shape so as to extend around the entire circumference in the circumferential direction of the ceramic plate.

[0027] According to the eighth embodiment of the susceptor, a wafer is placed on the first support wall, thereby forming a sealed space between the wafer and the ceramic plate, enclosed by the first support wall. According to the eighth embodiment of the susceptor, by supplying a gas to this sealed space, for example, to efficiently conduct heat between the wafer and the ceramic plate, the wafer can be heated efficiently and uniformly.

[0028] As a susceptor according to the ninth aspect of this disclosure, a susceptor according to any one aspect of the first to seventh aspects may be configured such that the first support wall is formed by a plurality of protrusions that extend along the circumferential direction of the ceramic plate and are spaced apart in the circumferential direction of the ceramic plate.

[0029] According to the ninth embodiment of the susceptor, when a wafer is placed on the first support wall, a space enclosed by the first support wall is formed between the wafer and the ceramic plate. According to the ninth embodiment of the susceptor, by supplying a gas to this space to efficiently conduct heat between the wafer and the ceramic plate, for example, the wafer can be heated uniformly. Furthermore, by discharging the gas from the space to the outside of the first support wall through the gap between adjacent protrusions, it is possible to suppress the formation of abnormal film deposition on the outer edge of the second main surface of the wafer when, for example, a film deposition process is performed on the wafer.

[0030] As a susceptor according to the tenth aspect of this disclosure, a susceptor according to any one aspect of the first to ninth aspects may be configured such that the wafer is a semiconductor substrate and is used for adsorption of the semiconductor substrate.

[0031] [Specific Examples of Embodiments] Next, specific embodiments of a susceptor in accordance with this disclosure will be described with reference to the drawings. In the drawings, identical or corresponding parts are given the same reference numerals.

[0032] Susceptors according to this disclosure are used as ceramic stands for supporting wafers in semiconductor manufacturing equipment. Examples of susceptors include electrostatic chucks for semiconductor etching equipment and ceramic heaters for semiconductor film deposition equipment. Examples of semiconductor film deposition equipment include chemical vapor deposition (CVD) equipment and physical vapor deposition (PVD) equipment.

[0033] Examples of wafers include semiconductor substrates and glass substrates. Wafers are preferably semiconductor substrates. Examples of semiconductors include silicon (Si), silicon carbide (SiC), and gallium nitride (GaN).

[0034] Figure 1 is a plan view of a susceptor 1 according to one embodiment of the present disclosure. Figure 2 is a schematic cross-sectional view of the susceptor 1 shown in Figure 1.

[0035] The susceptor 1 comprises a plate-shaped ceramic plate 2 and an electrostatic chuck electrode 3 embedded in the ceramic plate 2. The susceptor 1 may further include a resistance heating element 4 embedded in the ceramic plate 2. Inside the ceramic plate 2, for example, the electrostatic chuck electrode 3 is located near the first main surface 21 in the thickness direction of the ceramic plate 2, and the resistance heating element 4 is located further away from the first main surface 21 than the electrostatic chuck electrode 3 in the thickness direction of the ceramic plate 2.

[0036] (Description of ceramic plate) The ceramic plate 2 is formed by, for example, a sintered ceramic body. The ceramics are aluminum nitride (AlN), aluminum oxide (Al ２ O ３ ), silicon carbide (SiC), silicon nitride (Si ３ N ４ Examples include the above. The ceramic plate 2 only needs to be formed mainly from the ceramics described above, and may also contain components derived from sintering aids. Examples of sintering aids include rare earth metal oxides. Note that "main component" refers to containing 50% by mass or more, preferably 70% by mass or more, of ceramics.

[0037] Referring to Figures 1 and 2, the ceramic plate 2 is formed, for example, by a circular disc when viewed from a direction perpendicular to the first main surface 21. The size of the ceramic plate 2 is, for example, a diameter of 200 mm or more and 400 mm or less, and a thickness of 5 mm or more and 30 mm or less.

[0038] The ceramic plate 2 has a pair of main surfaces, a first main surface 21 and a second main surface 22, which are spaced apart in the thickness direction. The first main surface 21 includes a wafer support surface 23 that supports the wafer 10. The first main surface 21 and the second main surface 22 are parallel or approximately parallel. Note that "approximately parallel" includes cases where one is slightly inclined relative to the other, or where at least one is slightly distorted and not flat.

[0039] In the ceramic plate 2, the portion extending inward from the outer peripheral edge of the ceramic plate 2 on the first main surface 21 side by a predetermined width may be raised along the entire circumference of the ceramic plate 2 in the circumferential direction. This raised portion provides an outer wall 25 to the outer peripheral edge of the first main surface 21. The region of the first main surface 21 surrounded by the outer wall 25 is the wafer support surface 23. The outer wall 25 has an annular upper surface 24 located above the wafer support surface 23 in the thickness direction of the ceramic plate 2. The upper surface 24 of the outer wall 25 is parallel or approximately parallel to the wafer support surface 23. The wafer support surface 23 and the upper surface 24 of the outer wall 25 constitute the first main surface 21.

[0040] As shown in Figures 4 and 5, the ceramic plate 2 does not necessarily have an outer wall 25 on the outer peripheral edge of the first main surface 21. The first main surface 21 of the ceramic plate 2 may be flat or a generally flat surface.

[0041] Referring to Figures 1 and 2, the ceramic plate 2 is provided with a first support wall 5 that protrudes from the wafer support surface 23 of the first main surface 21. The first support wall 5 extends along the circumferential direction of the ceramic plate 2. In other words, the first support wall 5 extends parallel to the outer edge of the ceramic plate 2 at or inside the outer edge of the ceramic plate 2.

[0042] The first support wall 5 can be formed by an annular protrusion extending over the entire circumference in the circumferential direction of the ceramic plate 2, that is, an annular protrusion extending in parallel with the outer peripheral edge of the ceramic plate 2 over the entire circumference of the outer peripheral edge of the ceramic plate 2. In the present embodiment, the first support wall 5 is formed by an annular protrusion.

[0043] In the ceramic plate 2, the first support wall 5 is a portion where the wafer 10 is mainly placed. When the wafer 10 is placed on the first support wall 5, the wafer 10 is supported by the wafer support surface 23 of the ceramic plate 2. The tip surface 50 of the first support wall 5 contacts the second main surface 12 on the side of the pair of main surfaces 11 and 12 of the wafer 10 that faces the wafer support surface 23. Since the first support wall 5 is formed by an annular protrusion, a space 13 surrounded by the first support wall 5 is formed between the wafer 10 and the ceramic plate 2. A gas with good thermal conductivity, such as helium gas, is supplied to this space 13, for example, to efficiently conduct heat between the wafer 10 and the ceramic plate 2.

[0044] The shape of the cross-section perpendicular to the wafer support surface 23 of the first support wall 5 is, for example, rectangular or trapezoidal. The tip surface (tip surface) 50 protruding from the wafer support surface 23 in the first support wall 5 may be a flat surface or a substantially flat surface. The height of the first support wall 5, that is, the length that the first support wall 5 protrudes from the wafer support surface 23 (the vertical distance between the tip surface 50 of the first support wall 5 and the wafer support surface 23) is on the order of several μm to several hundred μm. Also, the width of the first support wall 5, that is, the distance between the inner peripheral surface and the outer peripheral surface of the first support wall 5 is on the order of 1 mm to 50 mm.

[0045] As shown in FIG. 3, the first support wall 5 may be integrally formed so as to be continuous with the outer wall 25.

[0046] Referring to FIGS. 1 and 2, the ceramic plate 2 may be provided with a plurality of support protrusions 6 protruding from the wafer support surface 23 on the first main surface 21. The plurality of support protrusions 6 are provided in a region surrounded by the first support wall 5 on the wafer support surface 23.

[0047] The cross-sectional shape of the support projection 6 perpendicular to the wafer support surface 23 is, for example, rectangular or trapezoidal. The end face (tip face) 60 of the support projection 6 that protrudes from the wafer support surface 23 may be a flat surface or a generally flat surface. The cross-sectional shape of the support projection 6 parallel to the wafer support surface 23 is, for example, circular or rectangular. The support projection 6 may be formed by cylindrical or frustoconical projections.

[0048] The height of the support projection 6, that is, the length that the support projection 6 protrudes from the wafer support surface 23 (the vertical distance between the tip surface 60 of the support projection 6 and the wafer support surface 23), is approximately a few micrometers to several hundred micrometers. The diameter of the support projection 6 is approximately 0.5 mm to 5 mm.

[0049] The tip surface 60 of the support projection 6 is located at the same height in the thickness direction of the ceramic plate 2 as the tip surface 50 of the first support wall 5. Note that "located at the same height" includes "located at approximately the same height," and even if the position differs slightly due to manufacturing variations, it is still considered to be located at the same height. In this embodiment, the length of the first support wall 5 that protrudes from the wafer support surface 23, which is the height of the first support wall 5, and the length of the support projection 6 that protrudes from the wafer support surface 23, which is the height of the support projection 6, are the same or approximately the same.

[0050] When the wafer 10 is supported on the wafer support surface 23 of the ceramic plate 2, the wafer 10 is placed not only on the first support wall 5 but also on the multiple support protrusions 6. The tip surfaces 60 of the multiple support protrusions 6 are in contact with the second main surface 12 of the wafer 10, and the wafer 10 is supported from below by the multiple support protrusions 6.

[0051] Multiple support protrusions 6 can be arranged at equal intervals from one another in the region enclosed by the first support wall 5 of the wafer support surface 23. By evenly arranging the multiple support protrusions 6, the entire wafer 10 is evenly supported by the wafer support surface 23.

[0052] In this embodiment, the portion of the ceramic plate 2 that comes into contact with the wafer 10 is the tip surface 50 of the first support wall 5 and the tip surfaces 60 of the multiple support protrusions 6. The ratio of the first support wall 5 to the total area of ​​the portion in contact with the wafer 10, that is, the ratio of the area of ​​the tip surface 50 of the first support wall 5 to the total area obtained by adding the area of ​​the tip surface 50 of the first support wall 5 and the area of ​​the tip surfaces 60 of the multiple support protrusions 6, is preferably 40% or more. In this embodiment, when only the first support wall 5 and the multiple support protrusions 6 are provided on the wafer support surface 23, this ratio is more preferably 45% or more, and even more preferably 50% or more. Furthermore, the ratio of the area of ​​the tip surface 50 of the first support wall 5 to the total area obtained by adding the area of ​​the tip surface 50 of the first support wall 5 and the area of ​​the tip surfaces 60 of the multiple support protrusions 6, is, for example, 95% or less, and preferably 90% or less. Because the area ratio of the tip surface 50 of the first support wall 5 is in the range of 40% to 95%, the first support wall 5 exerts sufficient adsorption force on the wafer 10, so that the wafer 10 is strongly adsorbed to the wafer support surface 23. Furthermore, when removing the wafer 10 from the wafer support surface 23, the wafer 10 can be detached from the first support wall 5 with good responsiveness.

[0053] Although not shown in the illustration, the ceramic plate 2 may have various holes that penetrate in the thickness direction. For example, holes can be formed in the ceramic plate 2 for inserting lift pins used to lift the wafer from the ceramic plate 2 after a process such as film deposition is completed. Alternatively, holes can be formed in the ceramic plate 2 for supplying gas to the space 13 surrounded by the first support wall 5 between the wafer 10 and the ceramic plate 2. The ceramic plate 2 may also have holes for passing thermocouples that detect the temperature of the ceramic plate 2.

[0054] (Explanation of electrostatic chuck electrode) Referring to Figure 2, the electrostatic chuck electrode 3 is provided between the first main surface 21 and the second main surface 22 of the ceramic plate 2, so as to spread out in a planar manner along a virtual plane that is parallel or approximately parallel to the first main surface 21.

[0055] Referring to Figures 6 to 9, the electrostatic chuck electrode 3 comprises at least one positive electrode 8 and at least one negative electrode 9. In this embodiment, the electrostatic chuck electrode 3 comprises one positive electrode 8 and one negative electrode 9. The pair of positive electrode 8 and negative electrode 9 are arranged in a planar manner on the same virtual plane between the first main surface 21 and the second main surface 22, spaced apart from each other and in a non-contact state.

[0056] The positive electrode 8 and the negative electrode 9 are formed from metallic materials such as molybdenum (Mo), tungsten (W), and ruthenium (Ru). The positive electrode 8 and the negative electrode 9 are formed using the above-mentioned materials, for example, in the form of thin plates or meshes, thereby creating a planar shape.

[0057] The ceramic plate 2 is provided with a power supply terminal for the positive electrode that is electrically connected to the positive electrode 8 and a power supply terminal for the negative electrode that is electrically connected to the negative electrode 9, although these are not shown in the figure. Each power supply terminal is connected to a DC power supply via a power supply member. A positive voltage is applied to the positive electrode 8 when the positive electrode of the DC power supply is electrically connected to it, and a negative voltage is applied to the negative electrode 9 when the negative electrode of the DC power supply is electrically connected to it. As a result, when a voltage is applied between the positive electrode 8 and the negative electrode 9, an adsorption force due to the Coulomb force or Johnson-Rabec force is generated on the first main surface 21 of the ceramic plate 2, and the wafer 10 is adsorbed to the wafer support surface 23. When the application of DC voltage to the positive electrode 8 and the negative electrode 9 is released, the adsorption of the wafer 10 by the wafer support surface 23 is released.

[0058] (Explanation of the electrode shapes of the positive and negative electrodes) Figure 6 shows a first example of the electrode shapes of the positive electrode 8 and the negative electrode 9. In the following explanation of the electrode shapes, "outer" and "inner" refer to the "outer" and "inner" parts of the ceramic plate 2 in the radial direction, respectively.

[0059] In the electrode configuration of the first example, the positive electrode 8 includes a plurality of first positive electrode portions 81, one second positive electrode portion 82, and one third positive electrode portion 83. Viewed from a direction perpendicular to the first main surface 21, the plurality of first positive electrode portions 81, one third positive electrode portion 83, and one second positive electrode portion 82 are arranged in this order from the outer edge of the ceramic plate 2 toward the center. The negative electrode 9 includes a plurality of first negative electrode portions 91, one second negative electrode portion 92, and one third negative electrode portion 93. Viewed from a direction perpendicular to the first main surface 21, the plurality of first negative electrode portions 91, one third negative electrode portion 93, and one second negative electrode portion 92 are arranged in this order from the outer edge of the ceramic plate 2 toward the center.

[0060] The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are located closest to the outer edge of the ceramic plate 2. The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged adjacent to the outer edge of the ceramic plate 2, but spaced apart in the circumferential direction of the ceramic plate 2. In other words, the multiple first positive electrode portions 81 are arranged along the outer edge of the ceramic plate 2, leaving space between adjacent first positive electrode portions 81 for one first negative electrode portion 91 to fit in. Similarly, the multiple first negative electrode portions 91 are arranged along the outer edge of the ceramic plate 2, leaving space between adjacent first negative electrode portions 91 for one first positive electrode portion 81 to fit in. As a result, the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2.

[0061] The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are located below the first support wall 5, which extends along the circumferential direction of the ceramic plate 2, when viewed from a direction perpendicular to the first main surface 21. In other words, when viewed from a direction perpendicular to the first main surface 21, the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2 such that each of the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 overlaps a portion of the annular region 26, which is the region on the first main surface 21 where the first support wall 5 is provided.

[0062] The first positive electrode portion 81 and the first negative electrode portion 91 are formed in a tapered shape, for example, with their width narrowing from the outer edge of the ceramic plate 2 towards the center, when viewed from a direction perpendicular to the first main surface 21. The first positive electrode portion 81 and the first negative electrode portion 91 are formed in a trapezoidal or fan shape, for example. As a result, when multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2, the multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged in a dense state with small gaps between adjacent first positive electrode portions 81 and first negative electrode portions 91.

[0063] The third positive electrode portion 83 and the third negative electrode portion 93 are located further away from the outer edge of the ceramic plate 2 than the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91. The third positive electrode portion 83 is formed in the shape of a "C" with a portion of the ring cut out, for example, when viewed from a direction perpendicular to the first main surface 21. The third negative electrode portion 93 is formed in the shape of a "C" with a portion of the ring cut out, for example, when viewed from a direction perpendicular to the first main surface 21. The third negative electrode portion 93 is embedded inside the third positive electrode portion 83, and the third positive electrode portion 83 is located closer to the outer edge of the ceramic plate 2 than the third negative electrode portion 93.

[0064] The second positive electrode portion 82 and the second negative electrode portion 92 are located furthest from the outer edge of the ceramic plate 2 and are located in the center of the ceramic plate 2. A power supply terminal for the positive electrode is electrically connected to the second positive electrode portion 82, and a power supply terminal for the negative electrode is electrically connected to the second negative electrode portion 92.

[0065] The second positive electrode portion 82 is formed in a "C" shape, for example, with a part of the ring cut out, when viewed from a direction perpendicular to the first main surface 21. The second negative electrode portion 92 is formed in a substantially circular shape, for example, when viewed from a direction perpendicular to the first main surface 21. The second positive electrode portion 82 is embedded inside the third negative electrode portion 93, and the second negative electrode portion 92 is embedded inside the second positive electrode portion 82, with the third positive electrode portion 83 being located closer to the outer edge of the ceramic plate 2 than the third negative electrode portion 93.

[0066] The third positive electrode portion 83 is connected to the second positive electrode portion 82 via a linear positive electrode second connecting portion 85 that penetrates the third negative electrode portion 93. One of the multiple first positive electrode portions 81 is connected to the third positive electrode portion 83. In the multiple first positive electrode portions 81, two adjacent first positive electrode portions 81 are connected by a linear positive electrode first connecting portion 84. The positive electrode first connecting portion 84 can connect two adjacent first positive electrode portions 81, for example, by passing outside the first negative electrode portion 91. As a result, the multiple first positive electrode portions 81, one second positive electrode portion 82, and one third positive electrode portion 83 are connected in a continuous manner.

[0067] On the other hand, the third negative electrode portion 93 is connected to the second negative electrode portion 92 via a linear negative electrode third connection portion 96 that penetrates the second positive electrode portion 82. One of the multiple first negative electrode portions 91 is connected to the third negative electrode portion 93 via a linear negative electrode second connection portion 95 that penetrates the third positive electrode portion 83. In the multiple first negative electrode portions 91, two adjacent first negative electrode portions 91 are connected by a linear negative electrode first connection portion 94, except for one location. The negative electrode first connection portion 94 can connect two adjacent first negative electrode portions 91, for example, by passing inside the first positive electrode portion 81. As a result, the multiple first negative electrode portions 91, one second negative electrode portion 92, and one third negative electrode portion 93 are connected in a continuous manner.

[0068] As described above, in this embodiment, by devising the electrode shape, a positive electrode 8 is formed in which a plurality of first positive electrode portions 81, one second positive electrode portion 82, and one third positive electrode portion 83 are connected in a continuous line, and a negative electrode 9 is formed in which a plurality of first negative electrode portions 91, one second negative electrode portion 92, and one third negative electrode portion 93 are connected in a continuous line and are not in contact with the positive electrode 8. As a result, while the electrostatic chuck electrode 3 is formed by one positive electrode 8 and one negative electrode 9, a plurality of first positive electrode portions 81 and a plurality of first negative electrode portions 91 can be alternately arranged in the circumferential direction of the ceramic plate 2 below the first support wall 5 when viewed from a direction perpendicular to the first main surface 21.

[0069] Figure 7 shows a second example of the electrode shapes of the positive electrode 8 and the negative electrode 9. With the electrode shapes of the second example shown in Figure 7, the electrostatic chuck electrode 3 can also be formed by one positive electrode 8 and one negative electrode 9, while a plurality of first positive electrode portions 81 and a plurality of first negative electrode portions 91 can be alternately arranged in the circumferential direction of the ceramic plate 2 below the first support wall 5 when viewed from a direction perpendicular to the first main surface 21.

[0070] In the electrode configuration of the second example, the positive electrode 8 includes a plurality of first positive electrode portions 81 and one second positive electrode portion 82. Viewed from a direction perpendicular to the first main surface 21, the plurality of first positive electrode portions 81 and the one second positive electrode portion 82 are arranged in this order from the outer edge of the ceramic plate 2 toward the center. The negative electrode 9 also includes a plurality of first negative electrode portions 91 and one second negative electrode portion 92. Viewed from a direction perpendicular to the first main surface 21, the plurality of first negative electrode portions 91 and the one second negative electrode portion 92 are arranged in this order from the outer edge of the ceramic plate 2 toward the center.

[0071] The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are located near the outer edge of the ceramic plate 2. The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged adjacent to the outer edge of the ceramic plate 2, but spaced apart in the circumferential direction of the ceramic plate 2. In other words, the multiple first positive electrode portions 81 are arranged along the outer edge of the ceramic plate 2, leaving space between adjacent first positive electrode portions 81 for one first negative electrode portion 91 to fit in. Similarly, the multiple first negative electrode portions 91 are arranged along the outer edge of the ceramic plate 2, leaving space between adjacent first negative electrode portions 91 for one first positive electrode portion 81 to fit in. As a result, the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2.

[0072] The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are located below the first support wall 5, which extends along the circumferential direction of the ceramic plate 2, when viewed from a direction perpendicular to the first main surface 21. In other words, when viewed from a direction perpendicular to the first main surface 21, the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2 such that each of the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 overlaps a portion of the annular region 26, which is the region on the first main surface 21 where the first support wall 5 is provided.

[0073] The first positive electrode portion 81 and the first negative electrode portion 91 are formed in a tapered shape, for example, with their width narrowing from the outer edge of the ceramic plate 2 towards the center, when viewed from a direction perpendicular to the first main surface 21. The first positive electrode portion 81 and the first negative electrode portion 91 are formed in a trapezoidal or fan shape, for example. As a result, when multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2, the multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged in a dense state with small gaps between adjacent first positive electrode portions 81 and first negative electrode portions 91.

[0074] The second positive electrode portion 82 and the second negative electrode portion 92 are located in the center of the ceramic plate 2. A power supply terminal for the positive electrode is electrically connected to the second positive electrode portion 82, and a power supply terminal for the negative electrode is electrically connected to the second negative electrode portion 92.

[0075] The second positive electrode portion 82 and the second negative electrode portion 92 are formed, for example, in a semicircular shape when viewed from a direction perpendicular to the first main surface 21. The second positive electrode portion 82 and the second negative electrode portion 92 are arranged to form a single circle by having portions corresponding to their respective diameters facing each other with a gap between them.

[0076] One of the multiple first positive electrode sections 81 is connected to the second positive electrode section 82. In the multiple first positive electrode sections 81, two adjacent first positive electrode sections 81 are connected by a linear positive electrode first connection section 84. The positive electrode first connection section 84 can connect two adjacent first positive electrode sections 81, for example, by passing outside the first negative electrode section 91. As a result, the multiple first positive electrode sections 81 and one second positive electrode section 82 are connected in a continuous line.

[0077] On the other hand, five of the multiple first negative electrode sections 91 are connected to the second negative electrode section 92. The remaining first negative electrode section 91 is connected to the second negative electrode section 92 via a linear fourth negative electrode connection section 97 that extends from the second negative electrode section 92 and passes inside the first positive electrode section 81. As a result, the multiple first negative electrode sections 91, one second negative electrode section 92, and multiple third negative electrode sections 93 are connected in a continuous line.

[0078] Figure 8 shows a third example of the electrode shapes of the positive electrode 8 and the negative electrode 9. With the electrode shapes of the third example shown in Figure 8, the electrostatic chuck electrode 3 can be formed by one positive electrode 8 and one negative electrode 9, while a plurality of first positive electrode portions 81 and a plurality of first negative electrode portions 91 can be alternately arranged in the circumferential direction of the ceramic plate 2 below the first support wall 5 when viewed from a direction perpendicular to the first main surface 21.

[0079] The electrode shape of the third example is a modification of the electrode shape of the second example shown in Figure 7 above, and only the differences will be explained here. In the electrode shape of the third example, the second positive electrode portion 82 and the second negative electrode portion 92 have a small diameter semicircular shape, and as a result, the multiple first positive electrode portions 81 and the first negative electrode portions 91 extend radially. In other words, the multiple first positive electrode portions 81 and the first negative electrode portions 91 extend between the vicinity of the outer edge and the vicinity of the center of the ceramic plate 2.

[0080] Figure 9 shows a fourth example of the electrode shapes of the positive electrode 8 and the negative electrode 9. With the electrode shapes of the fourth example shown in Figure 9, the electrostatic chuck electrode 3 can be formed by one positive electrode 8 and one negative electrode 9, while a plurality of first positive electrode portions 81 and a plurality of first negative electrode portions 91 can be alternately arranged in the circumferential direction of the ceramic plate 2 below the first support wall 5 when viewed from a direction perpendicular to the first main surface 21.

[0081] In the electrode configuration of the fourth example, the positive electrode 8 includes a plurality of first positive electrode portions 81, one second positive electrode portion 82, and a plurality of third positive electrode portions 83. Viewed from a direction perpendicular to the first main surface 21, the plurality of first positive electrode portions 81, the plurality of third positive electrode portions 83, and the one second positive electrode portion 82 are arranged in this order from the outer edge of the ceramic plate 2 toward the center. The negative electrode 9 includes a plurality of first negative electrode portions 91, one second negative electrode portion 92, and a plurality of third negative electrode portions 93. Viewed from a direction perpendicular to the first main surface 21, the plurality of first negative electrode portions 91, the plurality of third negative electrode portions 93, and the one second negative electrode portion 92 are arranged in this order from the outer edge of the ceramic plate 2 toward the center.

[0082] The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are located closest to the outer edge of the ceramic plate 2. The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged adjacent to the outer edge of the ceramic plate 2, but spaced apart in the circumferential direction of the ceramic plate 2. In other words, the multiple first positive electrode portions 81 are arranged along the outer edge of the ceramic plate 2, leaving space between adjacent first positive electrode portions 81 for one first negative electrode portion 91 to fit in. Similarly, the multiple first negative electrode portions 91 are arranged along the outer edge of the ceramic plate 2, leaving space between adjacent first negative electrode portions 91 for one first positive electrode portion 81 to fit in. As a result, the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2.

[0083] The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are located below the first support wall 5, which extends along the circumferential direction of the ceramic plate 2, when viewed from a direction perpendicular to the first main surface 21. In other words, when viewed from a direction perpendicular to the first main surface 21, the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2 such that each of the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 overlaps a portion of the annular region 26, which is the region on the first main surface 21 where the first support wall 5 is provided.

[0084] The first positive electrode portion 81 and the first negative electrode portion 91 are formed in a tapered shape, for example, with their width narrowing from the outer edge of the ceramic plate 2 towards the center, when viewed from a direction perpendicular to the first main surface 21. The first positive electrode portion 81 and the first negative electrode portion 91 are formed in a trapezoidal or fan shape, for example. As a result, when multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2, the multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged in a dense state with small gaps between adjacent first positive electrode portions 81 and first negative electrode portions 91.

[0085] The multiple third positive electrode portions 83 and the multiple third negative electrode portions 93 are located further away from the outer edge of the ceramic plate 2 than the multiple first positive electrode portions 81 and the multiple first negative electrode portions 91. The multiple first positive electrode portions 81 and the multiple first negative electrode portions 91 are adjacent to the multiple third positive electrode portions 83 and the multiple third negative electrode portions 93, but are spaced apart in the circumferential direction of the ceramic plate 2. In other words, the multiple third positive electrode portions 83 are arranged in the circumferential direction of the ceramic plate 2 with space between adjacent third positive electrode portions 83 for one third negative electrode portion 93 to fit in. Similarly, the multiple third negative electrode portions 93 are arranged in the circumferential direction of the ceramic plate 2 with space between adjacent third negative electrode portions 93 for one third positive electrode portion 83 to fit in. As a result, the multiple third positive electrode portions 83 and the multiple third negative electrode portions 93 are arranged alternately in the circumferential direction of the ceramic plate 2. The multiple third positive electrode portions 83 and the multiple third negative electrode portions 93 are arranged such that the third negative electrode portions 93 are located inside the first positive electrode portion 81, and the third positive electrode portions 83 are located inside the first negative electrode portion 91.

[0086] The third positive electrode portion 83 and the third negative electrode portion 93 are formed in a tapered shape, for example, with their width narrowing from the outer edge of the ceramic plate 2 towards the center, when viewed from a direction perpendicular to the first main surface 21. The third positive electrode portion 83 and the third negative electrode portion 93 are formed in a trapezoidal or fan shape, for example. As a result, when multiple third positive electrode portions 83 and multiple third negative electrode portions 93 are arranged alternately in the circumferential direction of the ceramic plate 2, the multiple third positive electrode portions 83 and multiple third negative electrode portions 93 are arranged in a dense state with small gaps between adjacent third positive electrode portions 83 and third negative electrode portions 93.

[0087] The second positive electrode portion 82 and the second negative electrode portion 92 are located furthest from the outer edge of the ceramic plate 2 and are located in the center of the ceramic plate 2. A power supply terminal for the positive electrode is electrically connected to the second positive electrode portion 82, and a power supply terminal for the negative electrode is electrically connected to the second negative electrode portion 92.

[0088] The second positive electrode portion 82 and the second negative electrode portion 92 are formed, for example, in a semicircular shape when viewed from a direction perpendicular to the first main surface 21. The second positive electrode portion 82 and the second negative electrode portion 92 are arranged to form a single circle by having portions corresponding to their respective diameters facing each other with a gap between them.

[0089] Five of the multiple third positive electrode sections 83 are connected to the second positive electrode section 82. The remaining third positive electrode sections 83 are connected to the second positive electrode section 82 via a linear positive electrode third connection section 86 that extends from the second positive electrode section 82 and passes inside the third negative electrode section 93. One of the multiple third positive electrode sections 83 is connected to one of the multiple first positive electrode sections 81. In the multiple first positive electrode sections 81, two adjacent first positive electrode sections 81 are connected by a linear positive electrode first connection section 84. The positive electrode first connection section 84 can connect two adjacent first positive electrode sections 81, for example, by passing outside the first negative electrode section 91. As a result, the multiple first positive electrode sections 81, one second positive electrode section 82, and multiple third positive electrode sections 83 are connected in a continuous sequence.

[0090] On the other hand, one of the multiple third negative electrode portions 93 is connected to the second negative electrode portion 92. One of the multiple first negative electrode portions 91 is connected to this one third negative electrode portion 93. Then, one of the third negative electrode portions 93 adjacent to the one third negative electrode portion 93 is connected to this one first negative electrode portion 91. This connection between the third negative electrode portion 93 and the first negative electrode portion 91 is repeated in the circumferential direction of the ceramic plate 2, thereby connecting multiple third negative electrode portions 93 and multiple first negative electrode portions 91. As a result, multiple first negative electrode portions 91, one second negative electrode portion 92, and multiple third negative electrode portions 93 are connected in a continuous line.

[0091] The electrode shapes of the positive electrode 8 and negative electrode 9 shown in Figures 6 to 9 described above are all illustrative examples, and the electrode shapes of the positive electrode 8 and negative electrode 9 are not particularly limited, as long as the electrostatic chuck electrode 3 is formed by one positive electrode 8 and one negative electrode 9, and a plurality of first positive electrode portions 81 and a plurality of first negative electrode portions 91 are alternately arranged in the circumferential direction of the ceramic plate 2 below the first support wall 5 when viewed from a direction perpendicular to the first main surface 21.

[0092] (Explanation of the resistive heating element) Referring to Figure 2, the resistive heating element 4 generates heat when an electric current is passed through it. The resistive heating element 4 can be formed from a metallic material such as molybdenum (Mo), tungsten (W), or niobium (Nb), or from a mixed material of this metallic material and ceramics. The ceramics used are the same material as the ceramics that are the main component of the ceramic plate 2.

[0093] The resistive heating element 4 is provided between the first main surface 21 and the second main surface 22 of the ceramic plate 2, so as to spread out in a planar manner along a virtual plane parallel or approximately parallel to the first main surface 21. When viewed from a direction perpendicular to the first main surface 21, the resistive heating element 4 is provided so as to spread out in a planar manner between the first main surface 21 and the second main surface 22 of the ceramic plate 2, by wiring, for example, a coil, or a planar meandering wire, or a plate-shaped printed electrode, formed using the above-mentioned material, in a predetermined pattern in a single continuous line manner, over almost the entire area from the center to the outer edge of the ceramic plate 2.

[0094] Although not shown in the figure, the ceramic plate 2 is provided with power supply terminals that are electrically connected to both ends of the resistive heating element 4. The pair of power supply terminals are connected to a DC power supply via a power supply member. When the resistive heating element 4 receives power from the DC power supply, it generates heat, which heats the entire ceramic plate 2, and the wafer 10 is heated via the heated wafer support surface 23.

[0095] The resistive heating element 4 can be configured as a first resistive heating element positioned near the center of the ceramic plate 2 when viewed from a direction perpendicular to the first main surface 21, and a second resistive heating element positioned near the outer edge of the ceramic plate 2. In this case, a power supply member is connected to a pair of power supply terminals electrically connected to both ends of the first resistive heating element, and a power supply member is connected to a pair of power supply terminals electrically connected to both ends of the second resistive heating element.

[0096] (Explanation of the operation and effect of the susceptor) According to the susceptor 1 of this embodiment, a plurality of first positive electrode portions 81 and a plurality of first negative electrode portions 91 are alternately arranged in the circumferential direction of the ceramic plate below the first support wall 5 on which the wafer 10 is placed inside the ceramic plate 2. Therefore, when a voltage is applied between the positive electrode 8 and the negative electrode 9, portions with high adsorption force and portions with low adsorption force alternately and in a balanced manner on the first support wall 5. Thus, according to the susceptor of this embodiment, bias in the adsorption of the wafer 10 by the first support wall 5 is suppressed, and the wafer 10 can be stably held on the first main surface 21.

[0097] Furthermore, according to the susceptor 1 of this embodiment, the ceramic plate 2 contains only one positive electrode 8 and one negative electrode 9 as electrostatic chuck electrodes 3. By devising the electrode shapes of the positive electrode 8 and the negative electrode 9, multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are arranged alternately in the circumferential direction of the ceramic plate 2 below the first support wall 5. Therefore, since only one power supply terminal for the positive electrode and one power supply terminal for the negative electrode need to be provided on the ceramic plate 2, the structure of the ceramic plate 2 can be simplified. In addition, the resistive heating element 4 built into the ceramic plate 2 needs to be positioned to avoid the power supply terminals, but since there is only one positive electrode 8 and one negative electrode built into the ceramic plate 2, only one power supply terminal for the positive electrode and one power supply terminal for the negative electrode need to be provided on the ceramic plate 2. Therefore, by wiring the resistive heating element 4 to avoid the power supply terminals, the formation of cool spots on the ceramic plate 2 can be reduced, and temperature unevenness is less likely to occur on the ceramic plate 2 when the ceramic plate 2 is heated by the resistive heating element 4. Therefore, according to the susceptor 1 of this embodiment, the uniformity of the heat distribution of the ceramic plate 2 can be improved.

[0098] Furthermore, according to the susceptor 1 of this embodiment, as shown in Figure 8 or 9, multiple first positive electrode portions 81 and multiple first negative electrode portions 91, or multiple third positive electrode portions 83 and multiple third negative electrode portions 93 are alternately arranged in the circumferential direction of the ceramic plate 2, not only below the first support wall 5 but also inside the first support wall 5. When a voltage is applied between the positive electrode 8 and the negative electrode 9, areas with high adsorption force and areas with low adsorption force are alternately and evenly distributed across almost the entire wafer support surface 23. Therefore, as shown in the example in Figure 8 or 9, the bias in the adsorption of the wafer 10 by the wafer support surface 23 is suppressed, and the wafer 10 can be stably held by the first main surface 21.

[0099] Furthermore, according to the susceptor 1 of this embodiment, the ceramic plate 2 can be heated by the resistance heating element 4 built into the ceramic plate 2, and the wafer 10 can be heated via the wafer support surface 23. At this time, since the wafer 10 is adsorbed by the wafer support surface 23 in a state where the unevenness of the adsorption force is suppressed, the wafer 10 can be heated uniformly.

[0100] Furthermore, according to the susceptor 1 of this embodiment, the wafer 10 is supported on the wafer support surface 23 not only by being placed on the first support wall 5, but also by being placed on the plurality of support protrusions 6. Therefore, the wafer 10 is stably supported by the first main surface 21. Moreover, if the wafer support surface 23 is evenly and alternately distributed with areas having high suction force and areas having low suction force, as in the example shown in Figure 8 or Figure 9, then bias in the suction of the wafer 10 by the plurality of support protrusions 6 is suppressed. Therefore, the wafer 10 can be stably held on the first main surface 21.

[0101] Furthermore, according to the susceptor 1 of this embodiment, the proportion of the first support wall 5 to the total area of ​​the portion of the ceramic plate 2 that contacts the wafer 10 is 40% or more. In this way, the first support wall 5 mainly contacts the wafer 10, allowing the wafer 10 to be stably held by the first main surface 21.

[0102] Furthermore, according to the susceptor 1 of this embodiment, when the wafer 10 is placed on the first support wall 5, a space 13 enclosed by the first support wall 5 is formed between the wafer 10 and the ceramic plate 2. Since this space 13 is sealed, the wafer 10 can be heated efficiently and evenly by supplying a gas to this space 13, for example, to efficiently conduct heat between the wafer 10 and the ceramic plate 2.

[0103] <Explanation of Modifications> The above describes a susceptor 1 according to one embodiment of the present disclosure. However, the embodiment can be modified in various ways without departing from the spirit of the present disclosure. For example, the following modifications are possible. The following modifications can be combined as appropriate.

[0104] As one variation, the first support wall 5 of the susceptor 1 may be formed by a plurality of protrusions 51 arranged at intervals in the circumferential direction of the ceramic plate 2, as shown in Figures 10 and 11. In the example shown in Figures 10 and 11, the first support wall 5 is formed by four protrusions 51, and the protrusions 51 are formed by arc-shaped projections in a quadrant. The four protrusions 51 are arranged to form a ring, with spaces 52 between adjacent protrusions 51.

[0105] In the examples shown in Figures 10 and 11, the wafer 10 can be heated uniformly by supplying a gas to the space 13 surrounded by the first support wall 5 between the wafer 10 and the ceramic plate 2, for example, to efficiently conduct heat between the wafer 10 and the ceramic plate 2. Furthermore, by discharging the gas from the space 13 to the outside of the first support wall 5 through the void 52 between adjacent protrusions 51, it is possible to suppress the formation of abnormal film deposition on the outer peripheral edge of the second main surface 12 of the wafer 10 when, for example, a film deposition process is performed on the first main surface 11 of the wafer 10.

[0106] As another variation, the ceramic plate 2 of the susceptor 1 may not be provided with multiple support protrusions 6, and may only have the first support wall 5.

[0107] As another variation, the ceramic plate 2 of the susceptor 1 may be provided with at least one second support wall 7 protruding from the wafer support surface 23 of the first main surface 21, in place of or in addition to the plurality of support protrusions 6, as shown in Figures 12 and 13. The second support wall 7 is provided in the region of the wafer support surface 23 surrounded by the first support wall 5. The second support wall 7 can be formed by an annular projection, such as a circular projection, that extends around the entire circumference of the ceramic plate 2 in the circumferential direction.

[0108] The cross-sectional shape of the second support wall 7 perpendicular to the wafer support surface 23 is, for example, rectangular or trapezoidal, and the end face (tip face) 70 of the second support wall 7 that protrudes from the wafer support surface 23 may be a flat surface or a generally flat surface. The height of the second support wall 7, that is, the length that the second support wall 7 protrudes from the wafer support surface 23 (the vertical distance between the tip face 70 of the second support wall 7 and the wafer support surface 23), is about a few micrometers to several hundred micrometers. The width of the second support wall 7, that is, the distance between the inner and outer surfaces of the second support wall 7, is about 0.5 mm to 50 mm.

[0109] The tip surface 70 of the second support wall 7 is located at the same height or approximately the same height as the tip surface 50 of the first support wall 5 in the thickness direction of the ceramic plate 2. In this embodiment, the length of the first support wall 5 that protrudes from the wafer support surface 23, which is the height of the first support wall 5, is the same as the length of the second support wall 7 that protrudes from the wafer support surface 23, which is the height of the second support wall 7.

[0110] When the wafer 10 is supported on the wafer support surface 23 of the ceramic plate 2, the wafer 10 is placed not only on the first support wall 5 but also on the second support wall 7. The leading edge surface 70 of the second support wall 7 is in contact with the second main surface 12 of the wafer 10, and the wafer 10 is supported from below by the second support wall 7.

[0111] In this embodiment, the portion of the ceramic plate 2 that contacts the wafer 10 is the tip surface 50 of the first support wall 5 and the tip surface 70 of the second support wall 7, or the tip surface 50 of the first support wall 5, the tip surfaces 60 of the plurality of support protrusions 6, and the tip surface 70 of the second support wall 7. In this embodiment as well, the proportion of the first support wall 5 to the total area of ​​the portion that contacts the wafer 10 is preferably 40% or more. When only the first support wall 5 and the second support wall 7 are provided on the wafer support surface 23, this proportion is more preferably 50% or more, and even more preferably 60% or more. When the first support wall 5, the plurality of support protrusions 6, and the second support wall 7 are provided on the wafer support surface 23, this proportion is more preferably 45% or more, and even more preferably 50% or more.

[0112] In the examples shown in Figures 12 and 13, the wafer 10 is placed on the first support wall 5 and the second support wall 7, thereby forming a first space surrounded by the second support wall 7 and a second space outside the second support wall 7, surrounded by the first support wall 5, between the wafer 10 and the ceramic plate 2. For example, by supplying gases with different thermal conductivity to the first and second spaces, the heat conduction from the ceramic plate 2 to the wafer 10 can be adjusted. Furthermore, the wafer 10 is supported on the first main surface 21 not only on the first support wall 5 but also on the second support wall 7. Thus, the wafer 10 is stably supported by the first main surface 21. Moreover, as shown in Figure 13, if multiple first positive electrode portions 81 and multiple first negative electrode portions 91 are alternately arranged in the circumferential direction of the ceramic plate 2 inside the first support wall 5, and if portions with high adsorption force and portions with low adsorption force are alternately and balanced across the entire first main surface 21, then bias in the adsorption of the wafer 10 by the second support wall 7 is suppressed. Therefore, the wafer 10 can be stably held on the first main surface 21.

[0113] As another variation, a cylindrical shaft made of ceramics may be joined to the second main surface 22 of the ceramic plate 2. Alternatively, a cooling plate having a refrigerant flow path inside may be joined to the second main surface 22 of the ceramic plate 2.

[0114] The embodiments disclosed herein should be understood to be illustrative in all respects and not restrictive in any way. The scope of the invention is defined not by the foregoing description but by the claims, and all modifications within the meaning and scope equivalent to the claims are intended.

[0115] 1: Susceptor, 2: Ceramic plate, 3: Electrostatic chuck electrode, 4: Resistive heating element, 5: First support wall, 6: Support projection, 7: Second support wall, 8: Positive electrode, 9: Negative electrode, 10: Wafer, 11: First main surface, 12: Second main surface, 13: Space, 14: Space, 21: First main surface, 22: Second main surface, 23: Wafer support surface, 24: Top surface, 25: Outer wall, 26: Annular region, 50: Tip Surface, 51: protrusion, 52: cavity, 60: tip surface, 70: tip surface, 81: first positive electrode part, 82: second positive electrode part, 83: third positive electrode part, 84: first positive electrode connection part, 85: second positive electrode connection part, 86: third positive electrode connection part, 91: first negative electrode part, 92: second negative electrode part, 93: third negative electrode part, 94: first negative electrode connection part, 95: second negative electrode connection part, 96: third negative electrode connection part, 97: fourth negative electrode connection part

Claims

1. A susceptor comprising a plate-shaped ceramic plate having a first main surface and a second main surface which are a pair of main surfaces located spaced apart in the thickness direction, wherein the ceramic plate is provided with a first support wall which extends along the circumferential direction of the ceramic plate and on which a wafer is placed, the ceramic plate has an electrostatic chuck electrode built in for adsorbing the wafer by electrostatic force, the electrostatic chuck electrode comprises a positive electrode to which a positive voltage is applied and a negative electrode to which a negative voltage is applied, the positive electrode includes a first positive electrode portion which overlaps with a part of the annular region on the first main surface to which the first support wall is provided when viewed from a direction perpendicular to the first main surface, the negative electrode includes a first negative electrode portion which overlaps with a part of the annular region when viewed from a direction perpendicular to the first main surface, and a plurality of the first positive electrode portion and the first negative electrode portion are arranged alternately in the circumferential direction of the ceramic plate.

2. The susceptor according to claim 1, wherein the electrostatic chuck electrode comprises one positive electrode and one negative electrode, the positive electrode includes a plurality of first positive electrode portions arranged at intervals in the circumferential direction of the ceramic plate and a second positive electrode portion connected to the plurality of first positive electrode portions and to which a power supply terminal for the positive electrode is electrically connected, and the negative electrode includes a plurality of first negative electrode portions arranged at intervals in the circumferential direction of the ceramic plate and a second negative electrode portion connected to the plurality of first negative electrode portions and to which a power supply terminal for the negative electrode is electrically connected.

3. The susceptor according to claim 2, wherein, when viewed from a direction perpendicular to the first main surface, the second positive electrode portion and the second negative electrode portion are located in the center of the ceramic plate, and one of the first positive electrode portion and the first negative electrode portion extends from the outer edge of the ceramic plate toward the center, and the other of the first positive electrode portion and the first negative electrode portion extends from the center of the ceramic plate toward the outer edge.

4. The susceptor according to claim 2, wherein, viewed from a direction perpendicular to the first main surface, the second positive electrode portion and the second negative electrode portion are arranged in the center of the ceramic plate, the positive electrode includes a plurality of third positive electrode portions that are spaced apart in the circumferential direction of the ceramic plate between a plurality of first positive electrode portions and the second positive electrode portions and connected to the plurality of first positive electrode portions and the second positive electrode portions, and the negative electrode includes a plurality of third negative electrode portions that are alternately arranged with the third positive electrode portions in the circumferential direction of the ceramic plate between a plurality of first negative electrode portions and the second negative electrode portions and connected to the plurality of first negative electrode portions and the second negative electrode portions.

5. The susceptor according to claim 2, wherein the ceramic plate has a built-in resistance heating element that generates heat when an electric current is applied.

6. The susceptor according to claim 3 or 4, wherein the ceramic plate is provided with at least one of the plurality of support protrusions and at least one second support wall extending along the circumferential direction of the ceramic plate in a region surrounded by the first support wall on the first main surface, and the tips of the support protrusions and the tips of the second support wall are at the same height as the tips of the first support wall in the thickness direction of the ceramic plate.

7. The susceptor according to claim 6, wherein the ratio of the first support wall to the total area of ​​the portion of the ceramic plate that contacts the wafer is 40% or more.

8. The susceptor according to claim 1 or 2, wherein the first support wall is formed in an annular shape so as to extend over the entire circumference in the circumferential direction of the ceramic plate.

9. The susceptor according to claim 1 or claim 2, wherein the first support wall is formed by a plurality of protrusions that extend along the circumferential direction of the ceramic plate and are spaced apart in the circumferential direction of the ceramic plate.

10. The susceptor according to claim 1 or claim 2, wherein the wafer is a semiconductor substrate and is used for adsorption of the semiconductor substrate.

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