Ceramic heater, kit including same, and method for adjusting heat dissipation characteristics of ceramic heater

Abstract

A ceramic heater is provided that can easily adjust the temperature profile to suit an actual heat dissipation environment without the need to remanufacture the ceramic heater. The ceramic heater includes a ceramic plate in which a heater electrode is embedded, an upper shaft having a flange at its lower end attached to the ceramic plate, a lower shaft having a flange at its upper end provided below the upper shaft, a spacer interposed between the upper shaft and the lower shaft, the spacer being (i) made of an O-ring or (ii) made of a cylindrical intermediate shaft having a pair of O-rings arranged at its upper and lower ends, and a clamp that engages with the flange of the upper shaft and the flange of the lower shaft to detachably fasten the upper shaft, the spacer, and the lower shaft, and is configured so that the lower shaft and / or the intermediate shaft can be replaced with a substitute lower shaft and / or a substitute intermediate shaft by releasing the fastening by the clamp.

Description

[Technical field]

[0001] The present invention relates to a ceramic heater, a kit including the same, and a method for adjusting the heat dissipation characteristics of a ceramic heater. [Background technology]

[0002] In a film forming apparatus for a semiconductor manufacturing process, a ceramic heater is used as a support stage for uniformly controlling the temperature of a wafer. A widely used ceramic heater includes a ceramic plate on which the wafer is placed and a cylindrical ceramic shaft attached to the ceramic plate.

[0003] A method of connecting different materials to achieve accurate temperature control as the shaft of a ceramic heater is known. For example, Patent Document 1 (JP 2016-178284 A) discloses a pedestal including a ceramic body in which a heating element is embedded, a first shaft connected to the ceramic body, and a second shaft connected to the first shaft, and it is described that the first shaft and the second shaft can be made of materials having different thermal conductivity properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-178284 A Summary of the Invention

[0005] When designing the heater electrodes for a heater with a shaft, it is desirable to take into consideration the heat dissipation environment of the chamber in which it will be used. However, when the heat dissipation environment of the chamber is unknown, it is often assumed that the amount of heat dissipated by radiation is uniform across the surface, and the input power and the amount of heat dissipated from the shaft end are set based on the actual measured values ​​of similar products. However, the heat dissipation environment of the actual chamber may differ from the analytical conditions. In such cases, the temperature distribution within the plate surface is likely to differ from the analytical results, and it will take a long time to remanufacture an improved product that is suited to the heat dissipation environment of the actual chamber.

[0006] The inventors have now discovered that by configuring the upper and lower shafts to be detachably fastened with a clamp via a spacer of a specified structure, and allowing the heat dissipation characteristics of the ceramic heater to be adjusted by replacing parts, it is possible to provide a ceramic heater whose temperature profile can be easily adjusted to suit the actual heat dissipation environment, without the need to remanufacture the ceramic heater.

[0007] Therefore, an object of the present invention is to provide a ceramic heater whose temperature profile can be easily adjusted to suit the actual heat dissipation environment without the need to remanufacture the ceramic heater.

[0008] According to the present invention, the following aspects are provided. [Aspect 1] a circular ceramic plate having a first surface on which a wafer is placed and a second surface opposite to the first surface, and having a heater electrode embedded therein; a cylindrical upper shaft having a flange at a lower end and made of ceramic, the upper shaft being attached to the second surface of the ceramic plate; a cylindrical lower shaft provided below the upper shaft and having a flange at an upper end; a spacer interposed between the upper shaft and the lower shaft, the spacer being (i) made of an O-ring, or (ii) made of a cylindrical intermediate shaft having a pair of O-rings disposed at upper and lower ends; a clamp that engages with a flange of the upper shaft and a flange of the lower shaft to detachably fasten the upper shaft, the spacer, and the lower shaft; wherein the lower shaft and / or the intermediate shaft are configured to be replaceable with an alternative lower shaft and / or an alternative intermediate shaft by releasing the fastening by the clamp, thereby making it possible to adjust the heat dissipation characteristics of the ceramic heater. [Aspect 2] 2. The ceramic heater of embodiment 1, wherein the alternative lower shaft has a different thermal conductivity and / or dimensions than the lower shaft. [Aspect 3] 3. The ceramic heater of claim 1 or 2, wherein the alternative intermediate shaft has a different thermal conductivity and / or dimensions than the intermediate shaft. [Aspect 4] The ceramic heater according to any one of aspects 1 to 3, wherein the clamp comprises an upper clamp portion that engages with the flange of the upper shaft, a lower clamp portion that engages with the flange of the lower shaft, and fastening means that fastens the upper clamp portion, the spacer, and the lower clamp portion together. [Aspect 5] The ceramic heater according to any one of aspects 1 to 4, wherein the spacer is formed of an O-ring. [Aspect 6] The ceramic heater according to any one of aspects 1 to 4, wherein the spacer is constituted by a cylindrical intermediate shaft having O-rings disposed at the upper and lower ends. [Aspect 7] A ceramic heater according to any one of aspects 1 to 6; a replacement part including one or more alternative lower shafts each having a different thermal conductivity and / or dimensions than the lower shaft and / or one or more alternative intermediate shafts each having a different thermal conductivity and / or dimensions than the intermediate shaft; A kit equipped with [Aspect 8] A method for adjusting the heat dissipation characteristics of the ceramic heater according to any one of aspects 1 to 6, comprising the steps of: releasing the clamp to remove the lower shaft and / or the intermediate shaft; replacing the removed lower shaft and / or intermediate shaft with a replacement lower shaft having a different thermal conductivity and / or dimensions than the lower shaft and / or a replacement intermediate shaft having a different thermal conductivity and / or dimensions than the intermediate shaft; reassembling the ceramic heater using the replaced alternative lower shaft and / or the replaced alternative middle shaft and the remaining parts that have not been replaced; The method for adjusting the heat dissipation characteristics of a ceramic heater includes: [Brief description of the drawings]

[0009] [Figure 1A] 1 is a cross-sectional view showing a schematic diagram of one embodiment of a ceramic heater according to the present invention. [Figure 1B] 1B is an enlarged cross-sectional view showing the periphery of a clamp of the ceramic heater shown in FIG. 1A. [Figure 1C] FIG. 1C is a cross-sectional view of the ceramic heater shown in FIG. 1B taken along line 1C-1C. [Figure 1D] FIG. 1D is a cross-sectional view of the ceramic heater shown in FIG. 1B taken along line 1D-1D. [Figure 1E] FIG. 1E is a cross-sectional view of the ceramic heater shown in FIG. 1B taken along line 1E-1E. [Figure 2A] FIG. 11 is an enlarged cross-sectional view showing the periphery of a clamp in another embodiment of the ceramic heater according to the present invention. [Figure 2B] FIG. 2B is a cross-sectional view showing the configuration of the ceramic heater shown in FIG. 2A after replacing the intermediate shaft with an alternative intermediate shaft of different dimensions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Ceramic Heater The ceramic heater according to the present invention is a ceramic platform for supporting a wafer while controlling the temperature in a semiconductor manufacturing device. Typically, the ceramic heater according to the present invention can be a ceramic heater for a semiconductor film forming device. Typical examples of the film forming device include a CVD (chemical vapor deposition) device (e.g., a thermal CVD device, a plasma CVD device, a photo CVD device, and an MOCVD device) and a PVD (physical vapor deposition) device.

[0011] 1A to 1E show one embodiment of a ceramic heater according to the present invention. The ceramic heater 10 shown in FIGS. 1A to 1E includes a disk-shaped ceramic plate 12, a cylindrical upper shaft 14, a cylindrical lower shaft 16, a spacer 18, and a clamp 20. A heater electrode 22 is embedded in the ceramic plate 12. The ceramic plate 12 has a first surface 12a on which a wafer (not shown) is placed and a second surface 12b opposite to the first surface 12a, and a cylindrical upper shaft 14 is attached to the second surface 12b. The upper shaft 14 is made of ceramics and has a flange 14a at its lower end. A cylindrical lower shaft 16 is provided below the upper shaft 14, and the lower shaft 16 has a flange 16a at its upper end. The spacer 18 is interposed between the upper shaft 14 and the lower shaft 16. The spacer 18 may be (i) made of an O-ring 24 as shown in Figs. 1A to 1E, or (ii) made of a cylindrical intermediate shaft 15 with a pair of O-rings 24 arranged at the upper and lower ends as shown in Fig. 2A described later. The clamp 20 engages with the flange 14a of the upper shaft 14 and the flange 16a of the lower shaft 16 to detachably fasten the upper shaft 14, the spacer 18 and the lower shaft 16. The lower shaft 16 and / or the intermediate shaft 15 are configured to be replaceable with an alternative lower shaft and / or an alternative intermediate shaft by releasing the fastening by the clamp 20, thereby making it possible to adjust the heat dissipation characteristics of the ceramic heater 10. In this manner, the upper shaft 14 and the lower shaft 16 are detachably fastened with the clamp 20 via the spacer 18 of a predetermined structure, and the heat dissipation characteristics of the ceramic heater 10 can be adjusted by replacing parts. This makes it possible to easily adjust the temperature profile of the ceramic heater 10 to suit the actual heat dissipation environment, without the need to remanufacture the ceramic heater 10.

[0012] As mentioned above, when designing a heater electrode for a heater with a shaft, if the heat dissipation environment of the chamber is unknown, the amount of heat dissipation by radiation is assumed to be uniform within the surface, and the input power and the amount of heat dissipation from the shaft end are often set based on the actual measured values ​​of similar products. However, if the heat dissipation environment of the actual chamber differs from the analysis conditions, the temperature distribution within the plate surface is likely to differ from the analysis result, and it was necessary to remanufacture an improved product that is suitable for the heat dissipation environment of the actual chamber. In this regard, according to the present invention, it is possible to easily adjust the temperature profile to suit the actual heat dissipation environment without having to remanufacture the ceramic heater 10. That is, as conceptually shown by the arrows in FIG. 1A, the heat dissipation of the ceramic heater 10 includes heat dissipation from the surface of the ceramic plate 12 and heat dissipation from the bottom end of the shaft. The heat dissipation from the surface of the ceramic plate 12 varies depending on the structure of the chamber in which the ceramic heater 10 is mounted, while the heat dissipation from the bottom end of the shaft varies depending on the thermal conductivity and dimensions of the shaft. Therefore, by preparing in advance a plurality of types of alternative lower shafts having heat dissipation characteristics (preferably thermal conductivity and / or dimensions) different from the lower shaft 16 and replacing the lower shaft 16 with an alternative lower shaft that is more suitable for the actual heat dissipation environment, the amount of heat dissipation from the lower shaft 16 can be changed. Also, by preparing in advance a plurality of types of alternative intermediate shafts having heat dissipation characteristics (preferably thermal conductivity and / or dimensions) different from the intermediate shaft 15 and replacing the intermediate shaft 15 with an alternative intermediate shaft that is more suitable for the actual heat dissipation environment, the amount of heat dissipation from the intermediate shaft 15 can be changed. Of course, the amount of heat dissipation from both the intermediate shaft 15 and the lower shaft 16 may be changed by replacing both the intermediate shaft 15 and the lower shaft 16 with an alternative intermediate shaft and an alternative lower shaft that are more suitable for the actual heat dissipation environment, respectively.

[0013] In any case, by such a simple part replacement, the heat dissipation characteristics of the ceramic heater 10 can be adjusted without the need to remanufacture the ceramic heater 10, and the in-plane temperature distribution of the ceramic plate 12 can be adjusted. Specifically, the in-plane temperature distribution of the ceramic plate 12 can be made uniform, the temperature at the center of the plane can be made lower, or the temperature at the center of the plane can be made higher. For example, to lower the temperature at the center of the plane, the intermediate shaft 15 and / or the lower shaft 16 can be replaced with an alternative intermediate shaft and / or an alternative lower shaft having a high thermal conductivity, thereby increasing the amount of heat dissipation from the lower shaft and lowering the temperature directly above the shaft. On the other hand, to raise the temperature at the center of the plane, the intermediate shaft 15 and / or the lower shaft 16 can be replaced with an alternative intermediate shaft and / or an alternative lower shaft having a low thermal conductivity, thereby decreasing the amount of heat dissipation from the lower shaft and raising the temperature directly above the shaft. Furthermore, by preparing multiple types of alternative intermediate shafts and alternative lower shafts in advance, it is possible to select the condition that is most suitable for the actual heat dissipation environment from among multiple conditions, thereby optimizing the heat dissipation characteristics of the ceramic heater 10 (and thus the in-plane temperature distribution of the ceramic plate 12).

[0014] The ceramic plate 12 may have the same structure as a ceramic plate used in a known ceramic heater. The main portion of the ceramic plate 12 other than the heater electrode 22 (i.e., the ceramic base) is preferably made of aluminum nitride from the viewpoints of excellent thermal conductivity, high electrical insulation, and thermal expansion characteristics similar to those of silicon.

[0015] The preferred shape of the ceramic plate 12 is a disk shape. However, the planar shape of the disk-shaped ceramic plate 12 does not need to be a perfect circle, and may be an incomplete circle with a part missing, such as an orientation flat. The size of the ceramic plate 12 may be appropriately determined according to the diameter of the wafer to be used, and is not particularly limited, but when it is a circle, the diameter is typically 150 to 450 mm, for example, about 300 mm.

[0016] The first surface 12a of the ceramic plate 12 may be provided with protrusions (not shown). The protrusions are preferably arranged at equal intervals on the first surface 12a of the ceramic plate 12. The shape of each protrusion is not particularly limited, but is preferably cylindrical. The diameter of each protrusion is not particularly limited, but is preferably 0.1 to 8 mm, more preferably 0.5 to 5 mm, even more preferably 0.5 to 4 mm, and particularly preferably 0.70 to 2.54 mm. The protrusions are preferably integrally formed with the ceramic plate 12 by embossing or the like. Therefore, the protrusions are preferably made of aluminum nitride, like the ceramic plate 12. The height of the protrusions is not particularly limited, but is preferably 0.001 to 0.1 mm, more preferably 0.005 to 0.08 mm, even more preferably 0.01 to 0.05 mm, and particularly preferably 0.01 to 0.03 mm. The distance between the central axes of adjacent projections is preferably 4 to 30 mm, more preferably 5 to 26 mm, further preferably 7 to 26 mm, and particularly preferably 7 to 15 mm.

[0017] A heater electrode 22 is embedded in the ceramic plate 12. The heater electrode 22 is not particularly limited, and may be, for example, a conductive coil wired in a single stroke across the entire surface of the ceramic plate 12. Heater rods 26 are connected to both ends of the heater electrode 22 for power supply, and the heater rods 26 are connected to a heater power source (not shown) via the internal space S of the upper shaft 14 and the lower shaft 16. When power is supplied from the heater power source, the heater electrode 22 generates heat and heats the wafer placed on the first surface 12a. The heater electrode 22 is not limited to a coil, and may be, for example, a ribbon (a long, thin plate) or a mesh.

[0018] An internal electrode other than the heater electrode 22 may be embedded in the ceramic plate 12. Examples of such internal electrodes include an ESC electrode and an RF electrode. The ESC electrode is an abbreviation of an electrostatic chuck (ESC) electrode, and is also called an electrostatic electrode. The ESC electrode is preferably a circular thin-layer electrode having a diameter slightly smaller than that of the ceramic plate 12, and may be, for example, a mesh-like electrode formed by weaving thin metal wires into a sheet shape. The ESC electrode may be used as a plasma electrode. That is, by applying a high frequency to the ESC electrode, the ESC electrode can also be used as a plasma electrode, and film formation can also be performed by a plasma CVD process. The ESC electrode is preferably connected to an ESC rod for power supply, and the ESC rod is preferably connected to an external power source (not shown) via the internal space S of the upper shaft 14 and the lower shaft 16. When a voltage is applied by the external power source, the ESC electrode chucks a wafer placed on the first surface 12a. The chucking force at this time is a force that is generated when the volume resistivity of aluminum nitride that can constitute the main part of the ceramic plate 12 is 1×10 8 ~1×10 13 is the Johnsen-Rahbek force because Ωcm.

[0019] The upper shaft 14 is a ceramic shaft attached to the second surface 12b of the ceramic plate 12, and has a flange 14a at the lower end. The upper shaft 14 may have the same configuration as a ceramic shaft used in a known ceramic heater, except that it has a flange 14a for fastening to the lower shaft 16 and is shorter in anticipation of the shaft length being supplemented by the lower shaft 16. The upper shaft 14 has an internal space S for accommodating the heater rod 26. The upper shaft 14 is preferably made of the same ceramic material as the ceramic plate 12. Therefore, the upper shaft 14 is preferably made of aluminum nitride. The upper end surface of the upper shaft 14 is preferably joined to the second surface 12b of the ceramic plate 12 by solid-state bonding or diffusion bonding. The outer diameter of the upper shaft 14 (excluding the flange 14a) is not particularly limited and is, for example, about 55 mm. The outer diameter of the flange 14a is also not particularly limited and is, for example, about 70 mm. The inner diameter of the upper shaft 14 (the diameter of the internal space S) is not particularly limited either, and is, for example, about 50 mm.

[0020] The lower shaft 16 is a cylindrical shaft provided below the upper shaft 14, and has a flange 16a at its upper end. The shape of the lower shaft 16 is not particularly limited as long as it can be connected to the upper shaft 14 or to the upper shaft 14 and the intermediate shaft 15 to form a single shaft. Therefore, like the upper shaft 14, the lower shaft 16 has an internal space S for accommodating the heater rod 26. The outer diameter of the lower shaft 16 (excluding the flange 16a), the outer diameter of the flange 16a, and the inner diameter of the lower shaft 16 (diameter of the internal space S) are not particularly limited, and may be equal to the outer diameter of the upper shaft 14 (excluding the flange 14a), the outer diameter of the flange 14a, and the inner diameter of the upper shaft 14, respectively. However, the material of the lower shaft 16 is not particularly limited. Unlike the upper shaft 14, the lower shaft 16 is farther away from the ceramic plate 12 that is heated to a high temperature, and therefore can be placed in a lower temperature environment than the upper shaft 14, which increases the range of material selection. Furthermore, by increasing the range of material choices for the lower shaft 16, materials with various thermal conductivity can be selected, which results in easier adjustment of the heat dissipation characteristics of the ceramic heater 10 by replacing the lower shaft with a substitute shaft. Therefore, the lower shaft 16 may be made of the same material as the upper shaft 14 (e.g., aluminum nitride), or may be made of any other material such as ceramics (e.g., alumina or zirconia), metals (e.g., aluminum or molybdenum), etc.

[0021] The spacer 18 is a general term for a member interposed between the upper shaft 14 and the lower shaft 16. Therefore, the spacer 18 may be configured with an O-ring 24 as shown in Figs. 1A and 1B, or may be configured with a cylindrical intermediate shaft 15 with a pair of O-rings 24 arranged at the upper and lower ends as shown in Fig. 2A. In either configuration, the presence of the spacer 18 makes it possible to avoid direct contact between the lower end of the upper shaft 14 and the upper end of the lower shaft 16, thereby mitigating the temperature effect on the lower shaft 16 due to heat conduction from the upper shaft 14. In addition, the presence of the O-ring 24 ensures airtightness of the joint between the shafts, which also contributes to mitigating the temperature effect on the lower shaft 16 from the upper shaft 14. As a result, as described above, the range of material selection for the lower shaft 16 and the intermediate shaft 15 is increased, and materials with various thermal conductivity can be selected, which results in easier adjustment of the heat dissipation characteristics of the ceramic heater 10 by replacing with an alternative lower shaft and / or an alternative intermediate shaft.

[0022] There are no particular limitations on the O-ring 24 as long as it is heat resistant, and a commercially available O-ring may be used. Preferred examples of materials constituting the O-ring 24 include nitrile rubber, and fluororubber is particularly preferred.

[0023] As shown in FIG. 2A, the intermediate shaft 15 is a cylindrical shaft provided between the upper shaft 14 and the lower shaft 16. The intermediate shaft 15 is not particularly limited in shape as long as it can be connected to the upper shaft 14 and the lower shaft 16 to form a single shaft. Thus, like the upper shaft 14 and the lower shaft 16, the intermediate shaft 15 has an internal space S for accommodating the heater rod 26. The inner diameter of the intermediate shaft 15 (diameter of the internal space S) is not particularly limited, and may be equal to the inner diameter of the upper shaft 14 and the inner diameter of the lower shaft 16. It is preferable that the outer diameter of the intermediate shaft 15 is equal to the outer diameter of the flange 14a of the upper shaft 14 and the outer diameter of the flange 16a of the lower shaft 16 from the viewpoint of sandwiching the O-ring 24 between the shafts when fastening with the clamp 20. The material of the intermediate shaft 15 is not particularly limited. This is because, unlike the upper shaft 14, the intermediate shaft 15 is located away from the ceramic plate 12, which is heated to a high temperature, and can be placed in a lower temperature environment than the upper shaft 14, thereby increasing the range of material selection. In addition, by increasing the range of material selection for the intermediate shaft 15, materials with various thermal conductivity can be selected, and as a result, it becomes easier to adjust the heat dissipation characteristics of the ceramic heater 10 by replacing it with a substitute intermediate shaft. Therefore, the intermediate shaft 15 may be made of the same material as the upper shaft 14 (e.g., aluminum nitride), or may be made of any other material, such as ceramics (e.g., alumina or zirconia), metals (e.g., aluminum or molybdenum), etc.

[0024] 1A to 1E, when the spacer 18 is configured with an O-ring 24, the amount of heat dissipation from the lower shaft 16 can be changed by replacing the lower shaft 16 with an alternative lower shaft having different heat dissipation characteristics (preferably thermal conductivity and / or dimensions). This embodiment is suitable for greatly adjusting the heat dissipation characteristics, since the lower shaft 16, a relatively large part that constitutes the lower half of the shaft, can be replaced with an alternative lower shaft.

[0025] 2A, when the spacer 18 is configured with a cylindrical intermediate shaft 15 with a pair of O-rings 24 (i.e., a total of two O-rings 24) arranged at the upper and lower ends, the amount of heat dissipation from the intermediate shaft 15 can be changed by replacing the intermediate shaft 15 with an alternative intermediate shaft having different heat dissipation characteristics (preferably thermal conductivity and / or dimensions). This embodiment is suitable for fine-tuning the heat dissipation characteristics, since the intermediate shaft 15, a relatively small part that constitutes the center of the shaft, can be replaced with an alternative intermediate shaft.

[0026] The clamp 20 engages with the flange 14a of the upper shaft 14 and the flange 16a of the lower shaft 16 to detachably fasten the upper shaft 14, the spacer 18, and the lower shaft 16. Preferably, the clamp 20 includes an upper clamp portion 20a, a lower clamp portion 20b, and a fastening means 20c. The upper clamp portion 20a engages with the flange 14a of the upper shaft 14, while the lower clamp portion 20b engages with the flange 16a of the lower shaft 16. The fastening means 20c fastens the upper clamp portion 20a, the spacer 18, and the lower clamp portion 20b. The fastening means 20c is not particularly limited as long as it has a configuration that allows detachable fastening, but is preferably composed of female threads cut in the upper clamp portion 20a and the lower clamp portion 20b, respectively, and a bolt that is screwed into the female threads. In this way, the upper shaft 14, the spacer 18, and the lower shaft 16 are detachably fastened.

[0027] In this way, the ceramic heater 10 is configured so that the lower shaft 16 and / or the intermediate shaft 15 can be replaced with an alternative lower shaft and / or an alternative intermediate shaft by releasing the fastening by the clamp 20, thereby making it possible to adjust the heat dissipation characteristics of the ceramic heater 10.

[0028] The alternative lower shaft preferably has a different thermal conductivity and / or dimensions than the lower shaft 16. By replacing the lower shaft 16 with an alternative lower shaft having a different thermal conductivity and / or dimensions, the amount of heat dissipated from the lower shaft 16 can be changed. The alternative lower shaft having a different thermal conductivity than the lower shaft 16 may be made of a material having a different thermal conductivity than the lower shaft 16. The alternative lower shaft having a different dimension than the lower shaft 16 preferably has a different length than the lower shaft 16. To achieve a different length from the lower shaft 16, the thickness T1 of the flange 16a may be changed, or the length of the portion of the lower shaft 16 other than the flange 16a may be changed.

[0029] The alternative intermediate shaft also preferably has a different thermal conductivity and / or dimensions than the intermediate shaft 15. By replacing the intermediate shaft 15 with an alternative intermediate shaft having a different thermal conductivity and / or dimensions, the amount of heat dissipation from the intermediate shaft 15 can be changed. The alternative intermediate shaft having a different thermal conductivity than the intermediate shaft 15 may be made of a material having a different thermal conductivity than the intermediate shaft 15. As shown in FIG. 2B, the alternative intermediate shaft 15' having a different dimension than the intermediate shaft 15 preferably has a thickness T2' different from the thickness T2 of the intermediate shaft 15 (the length of the intermediate shaft 15 in the central axis direction).

[0030] The alternative lower shaft employed in the embodiment shown in Figures 1A to 1E preferably has the same dimensions as the lower shaft 16 but a different thermal conductivity. That is, a preferred alternative lower shaft may be a shaft of the same dimensions as the lower shaft 16, which is made of a material having a different thermal conductivity than the lower shaft 16. By replacing the lower shaft 16 with such an alternative lower shaft of the same dimensions, the amount of heat dissipation from the lower shaft 16 can be changed without changing the dimensions of the lower shaft 16. This has the advantage that the heat dissipation characteristics of the ceramic heater 10 can be adjusted without changing the arrangement or design in the chamber.

[0031] The alternative intermediate shaft employed in the embodiment shown in Fig. 2A also preferably has the same dimensions as the intermediate shaft 15 but a different thermal conductivity. That is, a preferred alternative intermediate shaft may be a shaft having the same dimensions as the intermediate shaft 15 but made of a material different from that of the intermediate shaft 15. By replacing the intermediate shaft 15 with such an alternative intermediate shaft having the same dimensions, the amount of heat dissipation from the intermediate shaft 15 can be changed without changing the dimensions of the intermediate shaft 15. This has the advantage that the heat dissipation characteristics of the ceramic heater 10 can be adjusted without changing the arrangement or design within the chamber.

[0032] Alternatively, as shown in FIG. 2B, it is also preferable to employ an alternative intermediate shaft 15' having a thickness T2' different from the thickness T2 of the intermediate shaft 15. That is, by replacing the intermediate shaft 15 with an alternative intermediate shaft having a different thickness, the thickness of the intermediate shaft 15 can be adjusted, and the amount of heat dissipation from the intermediate shaft 15 can be changed. In this case, it is preferable to change the length of the lower shaft 16 so as to offset the change in thickness of the intermediate shaft 15 (i.e., so that the overall length of the shaft does not change). In this case, the lower shaft 16 is also replaced with an alternative lower shaft 16' having a different length. The change in length of the lower shaft 16 is preferably performed by changing the thickness T1 of the flange 16a. That is, if the total thickness (T1+T2) of the thickness T1 of the flange 16a and the thickness T2 of the intermediate shaft 15 is made equal to the total thickness (T1'+T2') of the thickness T1' of the flange 16a' of the alternative lower shaft 16' and the thickness T2' of the alternative intermediate shaft 15', there is no need to change the height of the clamp 20 or the height of the ceramic plate 12 based on the lower end of the lower shaft 16. That is, after replacing the intermediate shaft 15 and the lower shaft 16, the ceramic heater 10 can be extremely easily assembled into the chamber without any design changes.

[0033] kit The ceramic heater 10 according to the present invention is preferably provided in the form of a kit with an alternative lower shaft and / or an alternative intermediate shaft as a replacement part. In this way, a user can easily adjust the temperature profile of the ceramic heater 10 by using the replacement part so as to match the actual heat dissipation environment. That is, according to a preferred embodiment of the present invention, a kit is provided that includes the ceramic heater 10 and a replacement part including one or more alternative lower shafts and / or one or more alternative intermediate shafts. In this kit, the alternative lower shafts have different thermal conductivities and / or dimensions from the lower shaft 16, while the alternative intermediate shafts have different thermal conductivities and / or dimensions from the intermediate shaft 15. When the replacement part includes an alternative lower shaft, the number of types of the alternative lower shafts is not particularly limited, but is preferably 2 or more, more preferably 3 to 5 or 6 to 10. When the replacement part includes an alternative intermediate shaft, the number of types of the alternative intermediate shafts is not particularly limited, but is preferably 2 or more, more preferably 3 to 5 or 6 to 10. The more types of replacement parts there are, the more advantageous it is in that the heat dissipation characteristics can be adjusted in more stages.

[0034] How to adjust heat dissipation characteristics As described above, the ceramic heater 10 of the present invention has an advantageous configuration for adjusting the heat dissipation characteristics. The heat dissipation characteristics of the ceramic heater 10 are preferably adjusted in the following procedure. First, the clamp 20 is released to remove the lower shaft 16 and / or the intermediate shaft 15. Next, the removed lower shaft 16 and / or intermediate shaft 15 are replaced with an alternative lower shaft having a thermal conductivity and / or dimensions different from that of the lower shaft 16, and / or an alternative intermediate shaft having a thermal conductivity and / or dimensions different from that of the intermediate shaft 15. Finally, the ceramic heater 10 is reassembled using the replaced alternative lower shaft and / or alternative intermediate shaft and the remaining parts that have not been replaced. In this way, the temperature profile of the ceramic heater 10 can be easily adjusted to suit the actual heat dissipation environment without the need to remanufacture the ceramic heater 10.

Claims

1. a circular ceramic plate having a first surface on which a wafer is placed and a second surface opposite to the first surface, and having a heater electrode embedded therein; a cylindrical upper shaft having a flange at a lower end and made of ceramic, the upper shaft being attached to the second surface of the ceramic plate; a cylindrical lower shaft provided below the upper shaft and having a flange at an upper end; a spacer interposed between the upper shaft and the lower shaft, the spacer being (i) made of an O-ring, or (ii) made of a cylindrical intermediate shaft having a pair of O-rings disposed at upper and lower ends; a clamp that engages with a flange of the upper shaft and a flange of the lower shaft to detachably fasten the upper shaft, the spacer, and the lower shaft; wherein the lower shaft and / or the intermediate shaft can be replaced with an alternative lower shaft and / or an alternative intermediate shaft by releasing the fastening by the clamp, thereby making it possible to adjust the heat dissipation characteristics of the ceramic heater; the alternative lower shaft has a different thermal conductivity and / or dimensions than the lower shaft; and / or a ceramic heater, wherein the alternative intermediate shaft has a different thermal conductivity and / or dimensions than the intermediate shaft.

2. A circular ceramic plate having a first surface on which a wafer is placed and a second surface opposite to the first surface, and having a heater electrode embedded therein; a cylindrical upper shaft having a flange at a lower end and made of ceramic, the upper shaft being attached to the second surface of the ceramic plate; a cylindrical lower shaft provided below the upper shaft and having a flange at an upper end; a spacer interposed between the upper shaft and the lower shaft, the spacer being composed of a cylindrical intermediate shaft having a pair of O-rings disposed at upper and lower ends; a clamp that engages with a flange of the upper shaft and a flange of the lower shaft to detachably fasten the upper shaft, the spacer, and the lower shaft; wherein the lower shaft and / or the intermediate shaft are configured to be replaceable with an alternative lower shaft and / or an alternative intermediate shaft by releasing the fastening by the clamp, thereby making it possible to adjust heat dissipation characteristics of the ceramic heater.

3. The ceramic heater of claim 2 , wherein the alternate lower shaft has a different thermal conductivity and / or dimensions than the lower shaft.

4. 4. The ceramic heater of claim 2 or 3, wherein the alternative intermediate shaft has a different thermal conductivity and / or dimensions than the intermediate shaft.

5. The ceramic heater according to any one of claims 1 to 3, wherein the clamp comprises an upper clamp part that engages with a flange of the upper shaft, a lower clamp part that engages with a flange of the lower shaft, and fastening means for fastening the upper clamp part, the spacer and the lower clamp part together.

6. The ceramic heater of claim 1 , wherein the spacer is comprised of an O-ring.

7. 2. The ceramic heater according to claim 1, wherein the spacer is formed of a cylindrical intermediate shaft having O-rings disposed at the upper and lower ends.

8. A ceramic heater according to any one of claims 1 to 3, a replacement part including one or more alternative lower shafts each having a different thermal conductivity and / or dimensions than the lower shaft and / or one or more alternative intermediate shafts each having a different thermal conductivity and / or dimensions than the intermediate shaft; A kit equipped with

9. A method for adjusting the heat dissipation characteristics of the ceramic heater according to any one of claims 1 to 3, comprising the steps of: releasing the clamp to remove the lower shaft and / or the intermediate shaft; replacing the removed lower shaft and / or intermediate shaft with a replacement lower shaft having a different thermal conductivity and / or dimensions than the lower shaft and / or a replacement intermediate shaft having a different thermal conductivity and / or dimensions than the intermediate shaft; reassembling the ceramic heater using the replaced alternative lower shaft and / or the replaced alternative middle shaft and the remaining parts that have not been replaced; The method for adjusting the heat dissipation characteristics of a ceramic heater includes:

Images