JP2026008107A - Ceramic heater - Google Patents

Abstract

In a ceramic heater having an embedded member such as a mounting part in a ceramic plate, excessive heat generation (hot spots) near the embedded member is suppressed to improve the thermal uniformity of the ceramic plate.
[Solution] A ceramic heater includes a ceramic plate having a first surface and a second surface, a heater circuit embedded in the ceramic plate, and one or more embedded members embedded on the second surface side of the ceramic plate to a depth not in contact with the heater circuit and for attaching the ceramic plate to an external device or member. When the ceramic plate is viewed from above, the heater circuit overlaps with at least one of the embedded members to form an overlapping region. The heater circuit includes a heater main portion including a resistance heating element such as a coil, and a heater wire portion disposed in the overlapping region and consisting of a wire-like resistance heating element that is not coiled.
[Selected Figure] Figure 1

Description

This disclosure relates to ceramic heaters.

In film deposition equipment for semiconductor manufacturing processes, ceramic heaters are used as support stages to uniformly control the temperature of wafers. A widely used ceramic heater is one equipped with a ceramic plate on which the wafer is placed. Multi-zone ceramic heaters with multiple heating zones are also known as ceramic heaters.

Patent Document 1 (Japanese Patent No. 7030143) discloses an electrostatic chuck assembly including a puck including an electrically insulating upper back plate and a lower back plate, a cooling plate, conductive paths in the lower back plate, and a conductive gasket between the lower back plate and the cooling plate. The electrically insulating upper back plate includes one or more heating elements and one or more electrodes for electrostatically fixing a substrate. The lower back plate is joined to the upper back plate by metal bonding. The lower back plate also includes a plurality of structures distributed on the lower back plate at a plurality of different distances from the center of the lower back plate, each of the plurality of structures housing one of a plurality of fasteners. This document cites screw fasteners as examples of fasteners, and discloses fastening the lower back plate and the cooling plate with bolts.

Patent Document 2 (Japanese Patent No. 6637184) discloses a wafer mounting table comprising a ceramic plate, a metal plate, a threaded terminal, and a screw member. The ceramic plate incorporates at least one of an electrostatic electrode and a heater electrode and has a wafer mounting surface. The metal plate is disposed on the surface of the ceramic plate opposite the wafer mounting surface. The threaded terminal is made of a metal with a low thermal expansion coefficient and is bonded to a recess provided on the surface of the ceramic plate opposite the wafer mounting surface with a bonding layer containing ceramic fine particles and a hard brazing material. The screw member is inserted into a through-hole penetrating the metal plate and threadedly engages with the threaded terminal to fasten the ceramic plate to the metal plate. This document discloses an example of fastening using a threaded terminal, in which a female threaded terminal is brazed to a recess in an electrostatic chuck (ceramic plate).

Patent No. 7030143 Patent No. 6637184

Ceramic heaters are required to have small temperature differences within the surface on which the wafer is placed (i.e., thermal uniformity). In particular, with the recent trend toward finer process miniaturization and higher integration, ceramic heaters are required to have even greater thermal uniformity. From this perspective, it is desirable to minimize the temperature difference between areas where a resistance heating element is present and areas where it is not. To achieve this, it is preferable to distribute the resistance heating element throughout the entire area of the ceramic heater. Meanwhile, in recent years, heater designs in which mounting parts are located within the ceramic plate have also been proposed with the aim of improving mountability (e.g., Patent Documents 1 and 2). However, depending on the material of the mounting parts, a temperature difference can occur between the base of the ceramic plate and the mounting parts. As a result, the area of the ceramic plate near the mounting parts, combined with the heat generated by the resistance heating element, can become a hot spot, resulting in a problem of poor thermal uniformity for the ceramic heater.

The inventors have now focused on the overlapping region where the heater circuit overlaps with the embedded member in a planar view of a ceramic heater that has an embedded member such as an attachment part inside the ceramic plate, and discovered that by configuring the heater circuit located in this overlapping region with a wire-shaped (rather than coil-shaped) resistance heating element, it is possible to suppress excessive heat generation (hot spots) near the embedded member and improve the thermal uniformity of the ceramic plate.

Therefore, the object of the present invention is to suppress excessive heat generation (hot spots) near the embedded components in a ceramic heater that has mounting parts or other embedded components in the ceramic plate, thereby improving the thermal uniformity of the ceramic plate.

According to the present disclosure, the following aspects are provided.
[Aspect 1]
a ceramic plate having a first surface on which a wafer is placed and a second surface opposite to the first surface;
a heater circuit embedded in the ceramic plate;
one or more embedding members for attaching the ceramic plate to an external device or an external member, the embedding members being embedded in the ceramic plate on a second surface side thereof to a depth not in contact with the heater circuit;
Equipped with
When the ceramic plate is viewed from above, the heater circuit overlaps with at least one of the embedded members to form an overlapping region,
The heater circuit
a heater main portion that is disposed so as to be able to heat an area other than the overlapping area, and that includes a resistance heating element in at least one form selected from the group consisting of a coil, a linear zigzag structure, a printed pattern, a ribbon, and a mesh;
a heater wire portion disposed in the overlapping region and configured as a wire-like resistance heating element rather than a coil;
Including, ceramic heater.
[Aspect 2]
A ceramic heater according to aspect 1, wherein the wire-shaped resistance heating element has a diameter of 0.3 to 0.8 mm.
[Aspect 3]
3. The ceramic heater according to claim 1, wherein the number of the embedded members is three or more.
[Aspect 4]
A ceramic heater according to any one of Aspects 1 to 3, wherein the heater wire portion is disposed within the ceramic plate at a depth position spaced 5 to 20 mm from a top of the embedded member in a thickness direction.
[Aspect 5]
A ceramic heater according to any one of Aspects 1 to 4, wherein the heater wire portion is arranged to pass through an area within a radius of 15 mm from the center of the embedding member when the ceramic plate is viewed in a plan view.
[Aspect 6]
Aspect 6. The ceramic heater according to any one of aspects 1 to 5, wherein the ceramic plate comprises aluminum nitride or aluminum oxide.
[Aspect 7]
The ceramic heater according to any one of Aspects 1 to 6, wherein the resistance heating element comprises at least one selected from the group consisting of tungsten, molybdenum, a tungsten-molybdenum alloy, tungsten carbide, a tungsten carbide-titanium nitride composite material, a tungsten carbide-aluminum oxide composite material, and niobium.
[Aspect 8]
A ceramic heater according to any one of Aspects 1 to 7, wherein the heater main portion and the heater wire portion are a continuous, integrated resistance heating element.
[Aspect 9]
A ceramic heater according to any one of Aspects 1 to 7, wherein the heater main portion and the heater wire portion are separate resistance heating elements and are connected to each other via connection terminals.
[Aspect 10]
A ceramic heater according to aspect 9, wherein the connection terminal is a conductive member having two through holes with different diameters to which resistance heating elements with different wire diameters can be connected.
[Aspect 11]
A ceramic heater according to any one of Aspects 1 to 10, wherein the ceramic heater is a multi-zone ceramic heater including two or more heating zones.

1 is a schematic cross-sectional view showing an example of a ceramic heater according to the present invention. FIG. 2 is a schematic top view showing the ceramic heater shown in FIG. 1 . 2 is an enlarged schematic cross-sectional view showing the vicinity of an embedded member of the ceramic heater shown in FIG. 1. FIG. FIG. 2 is a plan view schematically illustrating an example of a configuration of a heater circuit including a connection terminal. FIG. 5 is a plan view schematically showing the connection terminal shown in FIG. 4 . FIG. 1 is a schematic cross-sectional view showing an example of a conventional ceramic heater.

The multi-zone ceramic heater according to the present invention is a ceramic platform for supporting a wafer in a semiconductor manufacturing device. Typically, the ceramic heater according to the present invention can be a ceramic heater for a semiconductor film deposition device. Typical examples of film deposition devices include CVD (chemical vapor deposition) devices (e.g., thermal CVD devices, plasma CVD devices, photo-assisted CVD devices, and MOCVD devices) and PVD (physical vapor deposition) devices.

Figures 1 and 2 show one embodiment of a ceramic heater. The ceramic heater 10 shown in Figures 1 and 2 comprises a ceramic plate 12, a heater circuit 14, and one or more embedded members 16. The ceramic plate 12 has a first surface 12a on which a wafer is placed and a second surface 12b opposite the first surface 12a. The heater circuit 14 is embedded within the ceramic plate 12. The embedded members 16 are members (e.g., mounting parts) for attaching the ceramic plate 12 to an external device or external member, and are embedded on the second surface 12b side of the ceramic plate 12 to a depth that does not contact the heater circuit 14. When the ceramic plate 12 is viewed from above, the heater circuit 14 overlaps with at least one of the embedded members 16, forming an overlap region O. The heater circuit 14 includes a heater main portion 14a and a heater wire portion 14b. The heater main portion 14a is arranged to heat areas other than the overlapping region O and includes a resistance heating element in at least one form selected from the group consisting of a coil, a linear zigzag structure, a printed pattern, a ribbon, and a mesh. Meanwhile, the heater wire portion 14b is arranged in the overlapping region O and is composed of a wire-like resistance heating element rather than a coil. In this way, in a ceramic heater 10 having an embedded member 16, such as an attachment part, within the ceramic plate 12, attention is focused on the overlapping region O where the heater circuit 14 overlaps with the embedded member 16 in a planar view. By configuring the heater circuit 14 arranged in this overlapping region O with a wire-like resistance heating element (i.e., the heater wire portion 14b) rather than a coil-like resistance heating element, excessive heat generation (hot spots) near the embedded member 16 can be suppressed, improving the thermal uniformity of the ceramic plate 12.

As mentioned above, with the recent trend toward finer process miniaturization and higher integration, ceramic heaters are required to have even greater thermal uniformity. To achieve this, it is preferable to distribute the resistance heating element evenly across the entire surface of the ceramic heater. Meanwhile, heater designs in which mounting parts are located within the ceramic plate have also been proposed in recent years to improve mountability (e.g., Patent Documents 1 and 2). However, depending on the material of the mounting parts, a temperature difference may occur between the ceramic plate base and the mounting parts. As a result, the area of the ceramic plate near the mounting parts, combined with the heat generated by the resistance heating element, may become a hot spot, resulting in poor thermal uniformity of the ceramic heater. Specifically, in a conventional ceramic heater 110 shown in Figure 6, in which an embedded member 116, such as a coil-shaped heater circuit 114 and mounting parts, is embedded within the ceramic plate 112, excessive heat generation is observed near the embedded member 116, and the surface of the ceramic plate 112 near the embedded member 116 may become a hot spot H. This is thought to be because the heat generated by the coil-shaped heater circuit 114 is less likely to escape locally due to the presence of the embedded member 116. Therefore, in the present invention, as shown in FIG. 1, the heater circuit 14 disposed in the overlap region O is configured with a wire-shaped (not coil-shaped) resistance heating element (i.e., heater wire portion 14b). This prevents excessive heat generation (hot spots H) near the embedded member 16 and improves the thermal uniformity of the ceramic plate 12. In other words, by using a wire-shaped resistance heating element (simple, unwound resistance heating wire) with a low heat output as the heater circuit 14 in the area corresponding to the embedded member 16, where localized high temperatures may occur, excessive heat generation in that area and the resulting occurrence of hot spots H can be prevented.

The main portion of the ceramic plate 12 (i.e., the ceramic substrate) excluding the heater circuit 14, embedded components 16, and other embedded components preferably contains aluminum nitride or aluminum oxide, more preferably aluminum nitride, from the standpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

The ceramic plate 12 is preferably 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 diameter of the ceramic plate 12 is 220 mm or more, typically 220 to 450 mm, and particularly for 300 mm silicon wafers, typically 320 to 380 mm. The thickness of the ceramic plate 12 is typically 10 to 25 mm.

The ceramic plate 12 may be a ceramic plate assembly in which an upper ceramic plate 12c providing the first surface 12a and a lower ceramic plate 12d providing the second surface 12b are joined together. In this case, it is preferable that an embedded member 16 be provided in the lower ceramic plate 12d, but this is not limited thereto; the embedded member 16 may also penetrate the lower ceramic plate 12d in the thickness direction and reach the upper ceramic plate 12c.

As shown in FIG. 1, the heater circuit 14 includes a heater main portion 14a arranged so as to be able to heat areas other than the overlapping area O, and a heater wire portion 14b arranged in the overlapping area O. It is preferable that the heater circuit 14, including the heater main portion 14a and the heater wire portion 14b as a whole, be arranged so as to be able to heat the entire area of the ceramic plate 12.

The heater main portion 14a includes a resistive heating element in at least one form selected from the group consisting of a coil, a linear zigzag structure, a printed pattern, a ribbon, and a mesh. A coil has a configuration in which a resistive heating wire is wound three-dimensionally, while a linear zigzag structure has a configuration in which a resistive heating wire is alternately folded two-dimensionally within a plane. The printed pattern is not particularly limited, but typically has a pattern in which strip-shaped lines of the resistive heating element layer alternate between straight and bent (e.g., zigzag).

The heater wire portion 14b is composed of a wire-shaped resistance heating element that is not coiled (i.e., not wound). The diameter of the wire-shaped resistance heating element is preferably 0.3 to 0.8 mm, more preferably 0.3 to 0.5 mm. As shown in FIG. 3, the heater wire portion 14b is disposed within the ceramic plate 12 at a depth of preferably 5 to 20 mm, more preferably 10 to 20 mm, from the top of the embedded member 16 in the thickness direction, from the perspective of maintaining a certain distance from the embedded member 16 and uniformly distributing locally high temperatures. Furthermore, when the ceramic plate is viewed from above, the heater wire portion 14b can be disposed so as to pass through an area preferably within a radius of 15 mm, more preferably within a radius of 10 mm, from the center of the embedded member 16. Therefore, by using the heater wire portion 14b, the heater circuit 14 can be distributed throughout the ceramic plate 12 regardless of the position of the embedded member 16, which facilitates improving the thermal uniformity of the ceramic plate 12.

The heater main portion 14a and the heater wire portion 14b may be a continuous, integrated resistance heating element. Alternatively, the heater main portion 14a and the heater wire portion 14b may be separate resistance heating elements connected to each other via a connection terminal 15, as shown in Figures 4 and 5. In this case, the connection terminal 15 is preferably positioned on or near the outer periphery of the overlap region O. Therefore, the connection terminal 15 can be used to connect resistance heating elements with different wire diameters. In other words, this embodiment is advantageous when the wire diameter of the heater main portion 14a and the wire diameter of the heater wire portion 14b are different. As shown in Figure 5, the connection terminal 15 is preferably a conductive member having two through holes 15a of different diameters that can connect resistance heating elements with different wire diameters. In this configuration, the heater main part 14a and the heater wire part 14b are inserted into the two through holes 15a and crimped and/or fixed, respectively, to ensure electrical connection between the heater main part 14a and the heater wire part 14b. The shape of the connection terminal 15 is not particularly limited, but may be spherical, for example. Note that if the wire diameter of the heater main part 14a (e.g., coil) and the heater wire part 14b are the same, the connection terminal 15 is not necessary.

The resistive heating element that constitutes the heater circuit 14 (i.e., the heater main portion 14a, the heater wire portion 14b, and optionally the connection terminal 15) preferably contains at least one material selected from the group consisting of tungsten, molybdenum, a tungsten-molybdenum alloy, tungsten carbide, a tungsten carbide-titanium nitride composite material, a tungsten carbide-aluminum oxide composite material, and niobium.

The heater circuit 14 may be provided with a pair of heater terminals for supplying power to the heater circuit 14. Preferably, heater terminals are connected to both ends of the heater circuit 14. There may be two or more pairs of heater terminals. The heater terminals are rod-shaped, and the heater circuit 14 may be connected to a heater power supply via the rod-shaped heater terminals.

The embedded member 16 is a member (e.g., a mounting part) for attaching the ceramic plate 12 to an external device or component. The embedded member 16 may be made of a material different from that of the ceramic substrate of the ceramic plate 12. Preferably, the embedded member 16 is made of the same material as the resistance heating element. Therefore, the embedded member 16 preferably includes at least one selected from the group consisting of tungsten, molybdenum, a tungsten-molybdenum alloy, tungsten carbide, a tungsten carbide-titanium nitride composite material, a tungsten carbide-aluminum oxide composite material, and niobium. The embedded member 16 may have any shape that can function as an attachment part. For example, as shown in Figures 1 and 3, the embedded member 16 may include a large-diameter upper portion 16a having a relatively large diameter and a small-diameter lower portion 16b having a relatively small diameter. In this case, it is preferable to position the large-diameter upper portion 16a in the center of the ceramic plate 12 in the thickness direction and the small-diameter lower portion 16b on the second surface 12b side of the ceramic plate 12, as this prevents the embedded member 16 from becoming detached from the ceramic plate 12. It is also preferable that the embedded member 16 include a female-threaded portion 16c (e.g., a nut) with a female thread. This allows a fastening member 18, such as a bolt with a male thread for attachment to an external device or member, to be threadedly engaged with the female-threaded portion 16c of the embedded member 16 for fastening.

The number of embedded members 16 is preferably three or more, and more preferably six or more. With such a number, the ceramic plate 12 can be securely fixed to an external device or component. The number of embedded members 16 is preferably 25 or less, and more preferably 20 or less. With such a number, the number of embedded members 16 reduces the number of locations where thermal uniformity is locally reduced by the embedded members 16, making it easier to achieve good yields in the semiconductor manufacturing process. When there are multiple embedded members 16, they are preferably arranged evenly around the circumference of the ceramic plate 12, as shown in Figure 2. For example, the multiple embedded members 16 are preferably arranged rotationally symmetrically with respect to the central axis of the ceramic plate 12.

The ceramic heater 10 may be a multi-zone ceramic heater including two or more heating zones. In the case of a multi-zone heater (e.g., a two-zone heater), the ceramic plate 12 may include an inner zone and an outer zone when viewed in a plan view. The inner zone is defined as a circular region within a predetermined distance from the center of the ceramic plate 12. A central region is located at the center of the inner zone. The outer zone is defined as an annular region outside the inner zone. The outer zone may be divided into multiple outer subzones (e.g., two to four). For example, the outer zone may be composed of multiple outer subzones divided into arcs (e.g., two to four). Alternatively, the outer zone may have two or more concentric annular regions of different sizes that do not overlap each other. In this case, the outer zone will have at least a first outer zone adjacent to the inner zone and a second outer zone located outside the first outer zone. If necessary, a third or more outer zones may exist outside the second outer zone. However, the ceramic heater 10 of the present invention may also be a one-zone heater.

In the case of a multi-zone heater (e.g., a two-zone heater), the heater circuit 14 preferably includes an inner zone heater circuit, an outer zone heater circuit, and a pair of jumpers. The inner zone heater circuit is embedded in the inner zone of the ceramic plate 12. However, the inner zone heater circuit may extend not only to the inner zone but also to the outer zone. The outer zone heater circuit is embedded in the outer zone of the ceramic plate 12. However, the outer zone heater circuit may extend not only to the outer zone but also to the inner zone. Therefore, the inner zone heater circuit and the outer zone heater circuit may overlap each other when viewed from above. The pair of jumpers are embedded in the inner zone of the ceramic plate 12 so as not to contact the inner zone heater circuit and are electrically connected to the outer zone heater circuit. The inner zone heater circuit and the outer zone heater circuit may be arranged on the same plane in a cross-sectional view, or the inner zone heater circuit and the outer zone heater circuit may be arranged on different planes in a cross-sectional view. Each of the inner zone heater circuit and the outer zone heater circuit is preferably arranged in a single-stroke pattern when viewed from above. The single-stroke pattern can be in a variety of known shapes, such as a repeated pattern of alternating forward and backward strokes or a spiral shape.

The ceramic plate 12 may further include an RF electrode and/or an ESC electrode. In this case, the RF electrode and/or ESC electrode are preferably embedded in the ceramic plate 12 at a depth closer to the first surface 12a than the heater circuit 14. The RF electrode enables film deposition using a plasma CVD process when high-frequency waves are applied to it. The ESC electrode is an abbreviation for electrostatic chuck (ESC) electrode and is also called an electrostatic electrode. When voltage is applied to the ESC electrode from an external power source, it chucks a wafer placed on the surface of the ceramic plate 12 using 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 high-frequency waves to the ESC electrode, the ESC electrode can also be used as an RF electrode, allowing film deposition using a plasma CVD process. An RF terminal or ESC terminal for power supply is connected to the RF electrode or ESC electrode. The RF terminal or ESC terminal is rod-shaped, and the RF electrode or ESC electrode can be connected to an external power supply via the rod-shaped RF terminal or ESC terminal.

A cooling plate may be provided on the second surface 12b of the ceramic plate 12. The cooling plate may have a cooling plate configuration commonly used for ceramic heaters and electrostatic chucks. The cooling plate may be made of a metal such as aluminum or an aluminum alloy, or may be made of a metal matrix composite (MMC) such as SiSiCTi (a composite material containing Si, SiC, and Ti). A typical cooling plate is disc-shaped and may have internal flow channels through which a coolant can circulate.

The present invention will be explained in more detail using the following examples. However, the present invention is not limited to these examples.

Example 1
(1) Fabrication of Ceramic Heater Using the components shown below, a ceramic heater 10 having a cross-sectional structure as shown in FIG. 1 was fabricated by a known procedure.
<Component parts and their specifications>
Ceramic plate 12: a disk-shaped aluminum nitride sintered body (diameter: 330 mm, thickness: 20 mm) (with the heater circuit 14 and the embedded member 16 embedded inside)
Heater circuit 14: A circuit in which a heater main portion 14a (material: molybdenum, winding diameter: 3.5 mm, wire diameter: 0.5 mm) made of a three-dimensional coil-shaped resistance heating element embedded in a predetermined circuit pattern at a depth of 10 mm from the first surface 12a, and a heater wire portion 14b made of a simple resistance heating wire (material: molybdenum, wire diameter: 0.4 mm, disposed in an overlapping region O with the embedded member 16 in the ceramic plate 12) are connected by connection terminals 15 (see FIG. 4 ).
Heater wire portion 14b: Located at a depth position 5 mm away from the top of the embedded member 16 in the thickness direction, and arranged so as to pass through an area within a radius of 9 mm from the center of the embedded member 16 when the ceramic plate 12 is viewed from above. Embedded member 16: Three metal attachment parts having a large-diameter upper portion 16a and a small-diameter lower portion 16b (material: molybdenum, diameter of large-diameter upper portion 16a: 25 mm, diameter of small-diameter lower portion 16b: 10 mm, height of embedded member 16: 15 mm).
Heater terminals: Two nickel terminal rods connected to both ends of the heater circuit 14

(2) Evaluation The ceramic heaters obtained were evaluated as follows.

<Heat uniformity>
The ceramic heater 10 was placed in the chamber of a film forming apparatus. The chamber was evacuated and _N2 gas was introduced, setting the _N2 gas pressure in the chamber to 5 Torr. The ceramic heater 10 was heated to a set temperature of 650°C by supplying power to the heater circuit 14 via the heater terminals. At this set temperature, the temperature distribution on the first surface 12a of the ceramic plate 12 was measured using an infrared camera. Based on the obtained temperature distribution map, the difference between the maximum and minimum temperatures within a 300 mm diameter area (i.e., the maximum in-plane temperature difference) was calculated as an index of thermal uniformity. The results are shown in Table 1, and excessive heat generation (hot spots) near the embedded material was suppressed.

<Evaluation of uniform heating distribution>
As described above, the embedded member 16 reduces the number of locations where thermal uniformity is locally reduced, making it easier to achieve a good yield in the semiconductor manufacturing process. In other words, the region of the ceramic plate 12 located above the embedded member 16 has locally poor thermal uniformity, resulting in variations in thermal uniformity (thermal uniformity distribution) within the first surface 12a. This thermal uniformity distribution satisfies the preferred range (e.g., 10°C or less) for the maximum temperature difference within the surface in thermal uniformity evaluation, but suggests a state in which there are points within the surface where the temperature varies slightly. To evaluate this thermal uniformity distribution, the total area of the upper surface of the embedded member 16 is calculated as a projected area, and the ratio (%) of this projected area to the area (70,650 ^mm2 ) of a wafer-mounting surface with a diameter of 300 mm is calculated, and the ratio is then evaluated based on the following criteria:
The evaluation was made according to the following criteria: Grade A: The projected area of the embedded member is 15% or less; Grade B: The projected area of the embedded member is more than 15%. Grade A indicates that it is easier to achieve a good yield in the semiconductor manufacturing process than Grade B.

Examples 2 to 6
Ceramic heaters were produced and evaluated in the same manner as in Example 1, except that the number of embedded members and the depth positions of the heater wire portions were set as shown in Table 1. The results are shown in Table 1, and excessive heat generation (hot spots) near the embedded members was suppressed.

Example 7 (Comparison)
A ceramic heater was fabricated and evaluated in the same manner as in Example 1, except that the above-mentioned three-dimensional coil-shaped resistance heating element was used instead of the heater wire portion 14b in the overlapping region O of the ceramic plate 12 as shown in Figure 6 (i.e., the heater circuit 14 was composed of only the heater main portion 14a). The results are shown in Table 1, and hot spots H occurred in the locations corresponding to the overlapping region O as shown in Figure 6. In this example, since the heating uniformity was poor, it was determined that there was no need to evaluate the heating uniformity distribution, and this is shown as a blank (-) in Table 1.

As shown in Table 1, Examples 1 to 6, in which the heater circuit 14 in the overlapping region O was configured with a wire-shaped resistance heating element (i.e., heater wire portion 14b), showed a significantly smaller maximum in-plane temperature difference than Example 7 (comparison example), in which the heater circuit 14 in the overlapping region O was configured with a three-dimensional coil-shaped heater main portion 14a. Therefore, it can be seen that by adopting the configuration of the present invention, excessive heat generation (hot spots) near the embedded member can be suppressed, improving the thermal uniformity of the ceramic plate.

10, 110 Ceramic heater 12, 112 Ceramic plate 12a First surface 12b Second surface 12c Upper ceramic plate 12d Lower ceramic plate 14, 114 Heater circuit 14a Main heater portion 14b Heater wire portion 15 Connection terminal 15a Through hole 16, 116 Embedded member 16a Large diameter upper portion 16b Small diameter lower portion 16c Female thread portion 18 Fastening member O Overlapping region H Hot spot

Claims (11)

a ceramic plate having a first surface on which a wafer is placed and a second surface opposite to the first surface;
a heater circuit embedded in the ceramic plate;
one or more embedding members for attaching the ceramic plate to an external device or an external member, the embedding members being embedded in the ceramic plate on a second surface side thereof to a depth not in contact with the heater circuit;
Equipped with
When the ceramic plate is viewed from above, the heater circuit overlaps with at least one of the embedded members to form an overlapping region,
The heater circuit
a heater main portion that is disposed so as to be able to heat an area other than the overlapping area, and that includes a resistance heating element in at least one form selected from the group consisting of a coil, a linear zigzag structure, a printed pattern, a ribbon, and a mesh;
a heater wire portion disposed in the overlapping region and configured as a wire-like resistance heating element rather than a coil;
Including, ceramic heater. The ceramic heater according to claim 1, wherein the diameter of the wire-shaped resistance heating element is 0.3 to 0.8 mm. The ceramic heater according to claim 1 or 2, wherein the number of embedded members is three or more. The ceramic heater according to claim 1 or 2, wherein the heater wire portion is disposed within the ceramic plate at a depth of 5 to 20 mm in the thickness direction from the top of the embedded member. A ceramic heater as described in claim 1 or 2, wherein the heater wire portion is arranged to pass through an area within a radius of 15 mm from the center of the embedded member when the ceramic plate is viewed in plan. The ceramic heater of claim 1 or 2, wherein the ceramic plate comprises aluminum nitride or aluminum oxide. The ceramic heater according to claim 1 or 2, wherein the resistance heating element contains at least one material selected from the group consisting of tungsten, molybdenum, tungsten-molybdenum alloy, tungsten carbide, tungsten carbide-titanium nitride composite material, tungsten carbide-aluminum oxide composite material, and niobium. The ceramic heater according to claim 1 or 2, wherein the heater main portion and the heater wire portion are a continuous, integrated resistance heating element. A ceramic heater as described in claim 1 or 2, wherein the heater main portion and the heater wire portion are separate resistance heating elements and connected to each other via connection terminals. The ceramic heater of claim 9, wherein the connection terminal is a conductive member having two through holes of different diameters to which resistance heating elements of different wire diameters can be connected. 3. The ceramic heater according to claim 1, wherein the ceramic heater is a multi-zone ceramic heater including two or more heating zones.