ceramic susceptor

Abstract

A ceramic susceptor is provided that can preferably realize low impedance of an RF rod to suppress the increase in heat generation associated with high frequency. The ceramic susceptor comprises a disc-shaped ceramic plate having a first surface and a second surface, with an RF electrode and a heater electrode embedded therein; a cylindrical ceramic shaft installed on the second surface of the ceramic plate and having an internal space; an RF rod having one end directly or indirectly connected to the RF electrode and the other end extending protruding from the second surface and extending through the internal space; and a heater rod having one end directly or indirectly connected to the heater electrode and the other end extending protruding from the second surface and extending through the internal space. The RF rod comprises a source portion including an end portion inserted into a terminal hole formed on the second surface of the ceramic plate, a core portion extending from the source portion in a direction away from the second surface, and an outer portion made of a non-magnetic material covering the outer circumference of the core portion.

Description

Technology Field

[0001] The present disclosure relates to a ceramic susceptor. Background Technology

[0002] In film deposition or etching equipment for semiconductor manufacturing processes, susceptors are used to support wafers. As such a susceptor, a ceramic plate for loading wafers and a cylindrical ceramic shaft installed on the ceramic plate are widely used. The ceramic plate generally has a configuration in which internal electrodes, such as a heater electrode, an RF electrode, and an electrostatic chuck (ESC) electrode, are embedded inside a ceramic body composed of aluminum nitride (AlN) or the like, which has excellent heat resistance and corrosion resistance.

[0003] In a plasma CVD process, a ceramic susceptor equipped with a ceramic plate having an RF electrode and a heater electrode embedded therein is used. FIGS. 12 and 13 schematically illustrate an example of a conventional film deposition apparatus (100, 100') equipped with such a ceramic susceptor (110). The film deposition apparatus (100, 100') is equipped with a ceramic plate (112) having an RF electrode (114) and a heater electrode (116) embedded therein within a chamber (102), and a plasma upper electrode (104). A wafer (W) is loaded on the ceramic plate (112), while a ceramic shaft (118) is provided on the back side of the ceramic plate (112). In the film-forming device (100) shown in FIG. 12, the plasma upper electrode (104) is connected to an RF power source (106), while the RF electrode (114) is connected to ground (108) through an RF load (120). In this configuration, as indicated by the arrow in FIG. 12, RF is applied from the plasma upper electrode (104) to generate plasma, and the RF current flows to ground (108) through the RF load (120). In the film-forming device (100') shown in FIG. 13, the plasma upper electrode (104) is connected to ground (108), while the RF electrode (114) is connected to an RF power source (106) through an RF load (120). In this configuration, as indicated by the arrow in FIG. 13, RF is applied from the RF electrode (114) to generate plasma, and RF current flows from the RF electrode (114) to the plasma upper electrode (104) via the RF load (120).

[0004] Regarding ceramic susceptors equipped with such RF electrodes and heater electrodes, RF rods of various configurations are proposed.

[0005] Patent Document 1 (Japanese Patent Publication No. 7129587) discloses a wafer support having a ceramic body in which an RF electrode and a heater electrode are embedded, a hole provided from one side of the ceramic body toward the RF electrode, and an RF rod joined to the RF electrode exposed on the bottom surface of the hole. This RF rod is a hybrid rod composed of a first rod member made of Ni forming a region from the leading edge of the RF rod to a predetermined position (between the leading edge and the base edge), and a second rod member made of a non-magnetic material such as tungsten forming a region from the said predetermined position to the base edge of the RF rod.

[0006] Patent Document 2 (Japanese Patent Publication No. 6586259) discloses a wafer support comprising a ceramic body in which an RF electrode and a heater electrode are embedded, a hole provided from one side of the ceramic body toward the RF electrode, a rod made of Ni or Kovar (registered trademark) bonded to the RF electrode exposed on the bottom surface of the hole, and a thin film of a homologous element provided in a predetermined area on the outer surface of the rod. The thin film of a homologous element is provided in the area on the outer surface of the rod from the base portion of the rod to a predetermined position that is not inserted into the hole. Specifically, this document discloses an RF terminal in which an Au thin film (Au plating) is provided on a part of the outer surface of a rod made of Ni. Prior art literature

[0007] Japanese Patent Publication No. 7129587 Japanese Patent Publication No. 6586259

[0008] In recent years, along with the increase in RF power required for plasma CVD, RF current has also been increasing. For example, RF current has been gradually increasing in frequency, from 13.56 MHz to 27.12 MHz and further to 40 MHz. Furthermore, due to the skin effect, which becomes more pronounced with higher frequency, the impedance of the RF load is also on an upward trend. In addition, the applied plasma power has also increased from 1 kW to 3 kW in recent years, and as the RF load generates heat due to the RF current, deterioration of process results and degradation of connection parts (melting, burning, alteration, etc.) are becoming a reality. Therefore, to suppress heat generation caused by the RF current, it is considered to lower the impedance of the RF load. However, it has been found that when conventional configurations are adopted to achieve low impedance of the RF load, various defects occur.

[0009] The inventors have discovered that by employing an RF rod having, in addition to a source portion and a core portion, an outer portion made of a non-magnetic material covering the outer periphery of the core portion, a ceramic susceptor capable of preferably realizing low impedance of the RF rod to suppress the increase in heat generation associated with high frequency can be provided.

[0010] Accordingly, the objective of the present invention is to provide a ceramic susceptor capable of preferably realizing low impedance of an RF load to suppress the increase in heat generation associated with high frequency.

[0011] According to the present disclosure, the following aspects are provided.

[0012] [Mode 1]

[0013] A disc-shaped ceramic plate having a first surface and a second surface, with an RF electrode and a heater electrode embedded therein, and

[0014] A cylindrical ceramic shaft having an internal space and installed on the second surface of the ceramic plate, and

[0015] An RF rod having one end directly or indirectly connected to the RF electrode and the other end extending and protruding from the second surface and extending through the internal space, and

[0016] A heater rod having one end directly or indirectly connected to the heater electrode and the other end extending and protruding from the second surface and extending through the internal space

[0017] It is a ceramic susceptor equipped with,

[0018] The above RF load,

[0019] A root portion including an end portion that is inserted into a terminal hole formed on the second surface of the ceramic plate, and

[0020] A core portion extending from the above source portion in a direction away from the above second surface, and

[0021] An outer periphery composed of a non-magnetic material covering the outer periphery of the core portion above

[0022] Ceramic susceptor including

[0023] [Mode 2]

[0024] A ceramic susceptor described in Embodiment 1, wherein the non-magnetic material constituting the outer periphery comprises at least one selected from the group consisting of brass, titanium, stainless steel, chromium, tungsten, molybdenum, and gold.

[0025] [Mode 3]

[0026] A ceramic susceptor described in embodiment 1 or 2, wherein the surface of the outer periphery is plated with gold and / or chrome.

[0027] [Mode 4]

[0028] The above outsourcing part,

[0029] A tubular part comprising a tube-shaped member and / or a mesh-shaped member formed into a cylindrical shape, and

[0030] A ceramic susceptor described in any one of embodiments 1 to 3, comprising a cap portion that closes the end opposite to the source portion of the above-mentioned tubular portion.

[0031] [Mode 5]

[0032] A ceramic susceptor described in any one of embodiments 1 to 4, wherein the core portion and the source portion comprise nickel or titanium.

[0033] [Mode 6]

[0034] A ceramic susceptor described in any one of embodiments 1 to 5, wherein the core portion comprises a rod-shaped member, a cable-shaped member, or a combination thereof.

[0035] [Mode 7]

[0036] The above core part,

[0037] A first rod-shaped member constituting the portion of the root portion side of the core portion, and

[0038] A second rod-shaped member constituting the tip portion on the opposite side of the root portion of the above-mentioned core portion, and

[0039] A ceramic susceptor described in any one of embodiments 1 to 6, comprising a cable-shaped member interposed between the first rod-shaped member and the second rod-shaped member.

[0040] [Mode 8]

[0041] A ceramic susceptor described in any one of embodiments 1 to 6, wherein the core portion is composed of a single rod-shaped member.

[0042] [Mode 9]

[0043] A ceramic susceptor described in any one of embodiments 1 to 8, wherein the ceramic susceptor comprises a plurality of RF rods, and the plurality of RF rods are connected in the internal space by a connecting member made of a non-magnetic material having at least one shape selected from the group consisting of a mesh shape, a thin shape, and a plate shape.

[0044] [Mode 10]

[0045] A ceramic susceptor described in Embodiment 9, wherein the non-magnetic material constituting the connecting member comprises at least one selected from the group consisting of brass, titanium, stainless steel, chromium, tungsten, and molybdenum.

[0046] [Mode 11]

[0047] A ceramic susceptor described in any one of embodiments 1 to 10, wherein the above RF electrode also functions as an ESC electrode. Brief explanation of the drawing

[0048] FIG. 1 is a schematic top view illustrating an example of a ceramic susceptor according to the present disclosure. FIG. 2 is a schematic cross-sectional view showing the 2-2 line cross-section of the ceramic susceptor shown in FIG. 1 in the direction of use. FIG. 3 is a schematic cross-sectional view showing the 2-2 line cross-section of the ceramic susceptor shown in FIG. 1 in the direction of manufacture. FIG. 4 is a schematic cross-sectional view of the RF rod shown in FIG. 1 to 3. FIG. 5 is a schematic cross-sectional view illustrating another example of a ceramic susceptor of the present disclosure. Figure 6 is a schematic cross-sectional view of the RF rod shown in Figure 5. FIG. 7 is a plan view schematically illustrating another example of a ceramic susceptor of the present disclosure. FIG. 8 is a schematic cross-sectional view of the RF rod and connecting member shown in FIG. 7. FIG. 9 is a schematic top view of the RF rod and connecting member shown in FIG. 7 and FIG. 8. FIG. 10 is a schematic cross-sectional view of an RF rod in another example of the ceramic susceptor of the present disclosure. FIG. 11 is a schematic cross-sectional view illustrating an example of a terminal connection structure in a ceramic susceptor of the present disclosure. FIG. 12 is a schematic cross-sectional view illustrating an example of a conventional membrane apparatus. FIG. 13 is a schematic cross-sectional view illustrating another example of a conventional tabernacle device. Specific details for implementing the invention

[0049] The ceramic susceptor according to the present invention is a ceramic base for supporting a wafer within a semiconductor manufacturing apparatus. Preferably, the ceramic susceptor according to the present invention is a ceramic heater for a semiconductor film deposition apparatus. Typical examples of a film deposition apparatus include a CVD (Chemical Vapor Deposition) apparatus (e.g., a thermal CVD apparatus, a plasma CVD apparatus, a photoCVD apparatus, and an MOCVD apparatus) and a PVD (Physical Vapor Deposition) apparatus, and particularly preferably a plasma CVD apparatus.

[0050] FIGS. 1 to 3 illustrate an example of a ceramic susceptor (10), while FIG. 4 illustrates an example of an RF rod (20) included in the ceramic susceptor (10). The ceramic susceptor (10) comprises a ceramic plate (12), a ceramic shaft (18), an RF rod (20), and a heater rod (22). An RF electrode (14) and a heater electrode (16) are embedded in the ceramic plate (12). The ceramic plate (12) is in the shape of a disc and has a first surface (12a) for loading a wafer (not shown) and a second surface (12b) facing the first surface (12a). A cylindrical ceramic shaft (18) is installed on the second surface (12b) of the ceramic plate (12). The ceramic shaft (18) is cylindrical and has an internal space (S). The RF rod (20) is configured such that one end of the RF rod (20) is directly or indirectly connected to the RF electrode (14), and the other end of the RF rod (20) extends outward from the second surface (12b) and extends through the internal space (S). The heater rod (22) is configured such that one end of the heater rod (22) is directly or indirectly connected to the heater electrode (16), and the other end of the heater rod (22) extends outward from the second surface (12b) and extends through the internal space (S). The RF rod (20) comprises a source portion (24), a core portion (26), and an outer portion (28). The source portion (24) includes an end that is inserted into a terminal hole (12c) formed on the second surface (12b) of the ceramic plate (12). The core portion (26) extends from the source portion (24) in a direction away from the second surface (12b). The outer periphery (28) is made of a non-magnetic material and is provided to cover the outer periphery of the core (26).In this way, by employing an RF rod (20) having an outer portion (28) made of a non-magnetic material covering the outer portion (26) in addition to the source portion (24) and the core portion (26), a ceramic susceptor (10) can be provided that can preferably realize low impedance of the RF rod to suppress the increase in heat generation accompanying high frequency.

[0051] In other words, as mentioned above, the RF current has increased in conjunction with the increase in RF power required for plasma CVD in recent years. Furthermore, due to the skin effect, which becomes more pronounced with higher frequencies, the impedance of the RF load is also on the rise. Additionally, the applied plasma power has increased in recent years, and as the RF load generates heat due to the RF current, deterioration of process results and degradation of connection parts (melting, burning, alteration, etc.) are becoming a reality. Therefore, it is possible to consider lowering the impedance of the RF load to suppress heat generation caused by the RF current. However, if a conventional configuration is adopted to achieve low impedance of the RF load, various defects occur. For example, Patent Document 1 (Japanese Patent Publication No. 7129587) states that low impedance of the RF load was achieved in a W / Ni hybrid load utilizing a non-magnetic material and the Curie temperature. However, due to the low impedance characteristics, the temperature of the nickel portion does not rise rapidly in the early stages of the process, resulting in a long time until the Curie temperature is reached and the process stabilizes; consequently, a new problem has arisen in that it takes time to obtain the desired characteristics. In addition, the tungsten portion oxidizes due to long-term use, causing the process results to undergo aging (so-called aging). Furthermore, since the W / Ni hybrid rod has a large weight (about three times that of conventional rods), when stress is applied in the transverse direction (i.e., in a direction approximately perpendicular to the rod axis), the moment generated at the lead joint also increases proportionally to the weight ratio; consequently, there have been cases where the lead joint fractures due to transportation or handling. Meanwhile, Patent Document 2 (Japanese Patent Publication No. 6586259) discloses Au plating on a Ni rod as described above. However, it is difficult to perform plating on the entire rod after lead bonding. In addition, if Au plating was applied to the outer surface of the rod before soldering, there was also a problem where the Au plating melted and fell off during the soldering process between the rod and the ceramic heater.One or more of these various problems are resolved by the ceramic susceptor (10) of the present invention (particularly the RF rod (20) having a unique configuration). In particular, the outer periphery (28) of the RF rod (20), where RF current flows intensively due to the skin effect, is made of a non-magnetic material and is a separate component from the core part (26) and source part (24) that constitute the interior and bottom of the RF rod (20), thereby suppressing the increase in resistance when RF current flows intensively through the outer periphery (28). That is, unlike ferromagnetic materials, non-magnetic materials have the property that resistance does not increase even when a large amount of RF current flows. Therefore, by selectively employing a non-magnetic material in the outer periphery (28), low impedance is achieved, thereby suppressing the increase in heat generation associated with high frequency. At the same time, the role of supporting the RF rod (20) can be secured in the core part (26) and source part (24).

[0052] The ceramic plate (12) preferably comprises aluminum nitride or aluminum oxide, with respect to excellent thermal conductivity, high electrical insulation, and thermal expansion properties similar to silicon, in a main part (i.e., ceramic body) other than the embedded member such as the RF electrode (14) and heater electrode (16), and more preferably aluminum nitride.

[0053] The ceramic plate (12) is in the shape of a disc. However, the shape of the disc-shaped ceramic plate (12) when viewed from a flat surface does not need to be a perfect circle, and may be an imperfect circle with a portion missing, such as an orientation flat. The size of the ceramic plate (12) can be appropriately determined according to the diameter of the wafer intended for use and is not particularly limited, but in the case of a circle, the diameter is typically 150 to 450 mm, and in particular for a 300 mm silicon wafer, it is typically 320 to 380 mm. In addition, the thickness of the ceramic plate (12) is typically 10 to 25 mm.

[0054] A terminal hole (12c) is provided on the second surface (12b) of the ceramic plate (12) to enable terminal connection to each of the RF electrode (14) and the heater electrode (16), and is configured to allow an RF rod (20) and a heater rod (22) to be inserted into the RF electrode (14) and the heater electrode (16), respectively. Additionally, a thermocouple hole (12d) for inserting a thermocouple (not shown) may be provided on the second surface (12b) of the ceramic plate (12).

[0055] The ceramic shaft (18) is a cylindrical member having an internal space (S) and may have a configuration similar to that of a ceramic shaft employed as a known ceramic susceptor or ceramic heater. The internal space (S) is configured so that terminal rods, such as an RF rod (20) and a heater rod (22), pass through it. It is preferable that the ceramic shaft (18) be composed of a ceramic material similar to that of the ceramic plate (12). Accordingly, it is preferable that the ceramic shaft (18) include aluminum nitride or aluminum oxide, and more preferably, aluminum nitride. It is preferable that the upper surface of the ceramic shaft (18) be bonded to the second surface (12b) of the ceramic plate (12) by solid-state bonding or diffusion bonding. The outer diameter of the ceramic shaft (18) is not particularly limited, but is preferably 40 to 60 mm. The inner diameter of the ceramic shaft (18) (the diameter of the internal space (S)) is also not particularly limited, but is preferably 33 to 55 mm.

[0056] The heater electrode (16) is not specifically limited, but may, for example, be a conductive coil wired in a manner that is continuously connected over the entire surface of the ceramic plate (12) without interruption. At both ends of the heater electrode (16), a heater rod (22) is connected directly or indirectly (for example, through a connecting member (17)) for power supply, and the heater rod (22) extends through the internal space (S) and is connected to a heater power source (not shown). When power is supplied from the heater power source, the heater electrode (16) generates heat and heats the wafer loaded on the surface of the ceramic plate (12). The heater electrode (16) is not limited to a coil and may, for example, be a ribbon (a thin, long sheet), a mesh, or a print.

[0057] The RF electrode (14) is an electrode that enables film formation by a plasma CVD process by applying a high frequency. The RF electrode (14) is preferably a circular thin-layer electrode with a diameter slightly smaller than that of the ceramic plate (12), and may be a mesh-shaped electrode formed by weaving thin metal wires into a net shape to form a sheet shape, for example. An RF rod (20) is connected to the RF electrode (14) directly or indirectly (for example, through a connecting member (15)) due to power supply, and the RF rod (20) extends through an internal space (S) and is connected to an external power source (see RF power source (106) in FIG. 13) or grounded (see grounding (108) in FIG. 12).

[0058] The RF electrode (14) may also function as an ESC electrode. The ESC electrode is an abbreviation for an electrostatic chuck (ESC) electrode and is referred to as an electrostatic electrode. When the RF electrode (14) functions as an ESC electrode, the RF electrode (14) (or ESC electrode) chucks a wafer loaded on the surface of the ceramic plate (12) by the Johnson-Rabek force when voltage is applied by an external power source.

[0059] The RF rod (20) has a source portion (24), a core portion (26), and an outer portion (28), and forms a rod shape overall.

[0060] The source portion (24) includes an end portion (24a) that is inserted into a terminal hole (12c) formed on the second surface (12b) of the ceramic plate (12). Accordingly, the end portion (24a) has a shape that can be inserted into the terminal hole (12c) (or the eyelet (42) described later with reference to FIG. 11). Additionally, it is preferable that the source portion (24) has a flange (24b) adjacent to the end portion (24a). The flange (24b) is a part that applies a force to press the RF rod (20) toward the ceramic plate (12) when inserting the RF rod (20) (particularly the end portion (24a)) into the terminal hole (12c), and it can also serve to position the end portion of the outer periphery (28).

[0061] The core portion (26) extends from the source portion (24) in a direction away from the second surface (12b). The core portion (26) preferably includes a rod-shaped member, a cable-shaped member, or a combination thereof. The core portion (26), together with the source portion (24), serves as a support for the RF rod (20). Additionally, it is preferable that the end adjacent to the source portion (24) of the core portion (26) has its diameter enlarged to form a coupling portion (27) that can be fitted or screw-coupled with the tube-shaped portion (30), thereby configuring the outer portion (28) to be fixed. Alternatively, the outer portion (28) may be configured to be fixed by providing a coupling portion (27) that can be fitted or screw-coupled with the tube-shaped portion (30) at the end adjacent to the source portion (24) of the core portion (26) as a different member (from the core portion (26) or the source portion (24). Accordingly, the connecting part (27) may be a part of the core part (26) or a different member from the core part (26). In any case, it is preferable that the connecting part (27) have a diameter equal to the inner diameter of the tubular part (30).

[0062] The core portion (26) and the source portion (24) preferably comprise nickel or titanium, and more preferably are composed of nickel or titanium. Since the core portion (26) and the source portion (24) made of nickel or titanium can maintain low electrical resistance, they are suitable for use as a part that carries DC current (for use in wafer chucking by an electrostatic chuck). Additionally, the core portion (26) and the source portion (24) are preferably composed of the same type of metal material.

[0063] According to a preferred embodiment of the present invention, as illustrated in FIG. 4, the core portion (26) may comprise a first rod-shaped member (26a) constituting a portion on the side of the source portion (24) of the core portion (26), a second rod-shaped member (26b) constituting a tip portion on the side opposite to the source portion (24) of the core portion (26), and a cable-shaped member (26c) interposed between the first rod-shaped member (26a) and the second rod-shaped member (26b). In this embodiment, the difference in thermal expansion rates between the non-magnetic material (e.g., brass) constituting the outer periphery (28) and the material (e.g., nickel) constituting the core portion (26) and the source portion (24) can be absorbed by the cable-shaped member (26c). That is, the cable-shaped member (26c) can be bent due to its own flexibility, thereby absorbing displacement caused by the difference in thermal expansion rates during high-temperature use. Alternatively, according to another preferred embodiment of the present invention, as illustrated in FIG. 5, 6 and 10, the core portion (26) may be composed of a single rod-shaped member (26a).

[0064] The outer periphery (28) is composed of a non-magnetic material and is a member provided to cover the outer periphery of the core part (26). As described above, unlike ferromagnetic materials, non-magnetic materials have the property that resistance does not increase even when a large amount of RF current flows. Therefore, by selectively employing a non-magnetic material in the outer periphery (28), low impedance can be achieved, thereby suppressing the increase in heat generation associated with high frequency. It is preferable that the non-magnetic material constituting the outer periphery (28) includes at least one type selected from the group consisting of brass, titanium, stainless steel, chromium, tungsten, molybdenum, and gold. However, it is more preferable to have the main part of the outer periphery (28) composed of the above-mentioned non-magnetic material other than gold or chromium, and for the gold or chromium to be applied to the surface of the outer periphery (28) in the form of plating. That is, it is preferable that the surface of the outer periphery (28) be plated with gold and / or chromium. Gold plating is particularly desirable as it also functions as an oxidation barrier for the non-magnetic material constituting the outer periphery (28). Additionally, since chrome plating also functions as a gold diffusion barrier layer as an underlayer for gold plating, it is desirable to use it in combination with gold plating.

[0065] The outer portion (28) preferably includes a tube-shaped portion (30) and a cap portion (32) that closes the end opposite to the source portion (24) of the tube-shaped portion (30). The tube-shaped portion (30) is preferably composed of a tube-shaped member and / or a mesh-shaped member formed into a cylindrical shape. Alternatively, the tube-shaped portion (30) may be a metal foil rounded into a tube shape. In any case, the tube-shaped portion (30) and the cap portion (32) are preferably plated with gold and / or chrome, as described above.

[0066] The installation of the outer periphery (28) on the core portion (26) can be performed, for example, as follows. First, a rod composed of the core portion (26) and the source portion (24) is soldered to the RF electrode (14) and / or the connecting member (15). Then, the outer periphery (28) (i.e., the tubular portion (30) and the cap portion (32)), which has been plated with gold plating or the like in advance, is installed on the core portion (26) or the connecting portion (27) by known methods such as screw fixing or spot welding so as to cover the outer periphery of the core portion (26).

[0067] According to a preferred embodiment of the present invention, as illustrated in FIGS. 5 and 6, the tubular shape portion (30) may comprise a first tube-shaped member (30a) constituting a portion on the side of the source portion (24) of the tubular shape portion (30), a second tube-shaped member (30b) constituting a front portion on the side opposite to the source portion (24) of the tubular shape portion (30), and a mesh-shaped member (30c) interposed between the first tube-shaped member (30a) and the second tube-shaped member (30b). In this embodiment, the difference in thermal expansion rates between the non-magnetic material (e.g., titanium) constituting the tubular shape portion (30) and the material (e.g., nickel) constituting the tubular shape portion (30) and the source portion (24) can be absorbed by the mesh-shaped member (30c). That is, the mesh-shaped member (30c) can be bent due to its own flexibility, thereby absorbing displacement caused by the difference in thermal expansion rates during high-temperature use. Since the first tube-shaped member (30a), the second tube-shaped member (30b), and the mesh-shaped member (30c) are components of the tube-shaped part (30), it is preferable that they be made of a non-magnetic material, similar to the constituent material of the tube-shaped part (30) described above, and that their surfaces be plated with gold and / or chrome. Examples of preferred mesh-shaped members (30c) include a mesh made of titanium, tungsten, or molybdenum with gold plating on its surface. Alternatively, according to another preferred embodiment of the present invention, as shown in FIGS. 1 to 4 and FIG. 10, the tube-shaped part (30) may be composed of a single tube-shaped member (30a). Preferred examples of this single tube-shaped member (30a) include a tube-shaped member made of brass or titanium with gold plating on its surface.

[0068] As illustrated in FIGS. 7 to 9, the ceramic susceptor (10) may be equipped with a plurality of RF rods (20). In this case, it is preferable that the plurality of RF rods (20) be connected in the internal space (S) by a connecting member (36) composed of a non-magnetic material of at least one shape selected from the group consisting of a mesh shape, a thin shape, and a plate shape. Since the RF rods (20) can be connected using a non-magnetic material having a planar shape and spreading, the impedance of the RF rods (20) can be further reduced. It is preferable that the non-magnetic material constituting the connecting member (36) includes at least one type selected from the group consisting of brass, titanium, stainless steel, chromium, tungsten, and molybdenum.

[0069] The heater rod (22) may have the same configuration as a heater rod employed as a known ceramic susceptor or ceramic heater. Accordingly, the heater rod (22) may be composed of the same material (e.g., nickel or titanium) as the core part (26) and source part (24) in the RF rod (20), and is not particularly limited.

[0070] As described above, the RF rod (20) is connected directly or indirectly to the RF electrode (14), while the heater rod (22) is connected directly or indirectly to the heater electrode (16). The RF rod (20) and the heater rod (22) may be directly connected to the RF electrode (14) and the heater electrode (16), respectively, by soldering, but as shown in FIGS. 2, 3, 5 and 7, they may be connected by soldering through a connecting member (15, 17) comprising a metal member such as Mo. The connecting member (15, 17) is not particularly limited and may have a known connecting structure comprising a metal member such as Mo.

[0071] FIG. 11 illustrates a preferred example of a connecting member (15, 17). The connecting member (15, 17) illustrated in FIG. 11 includes a metal member (40) and an eyelet (42).

[0072] The metal member (40) is a member that assists in securing electrical connection by interposing between the RF rod (20) and the RF electrode (14), and / or between the heater rod (22) and the heater electrode (16), and its configuration is not particularly limited. A preferred metal member (40) includes a tablet (40a) and / or a buffer (40b), and more preferably includes both the tablet (40a) and the buffer (40b). The tablet (40a) is a bulk metal member (e.g., configured in a mesh shape) to facilitate securing electrical connection between the RF rod (20) and the RF electrode (14), and is provided on the side of the RF electrode (14). Likewise, the tablet (40a) may also be provided on the side of the heater electrode (16) to secure electrical connection between the heater rod (22) and the heater electrode (16). By doing so, a sufficient contact area can be secured for soldering the RF rod (20), heater rod (22), and / or buffer material (40b). Preferred examples of the metal constituting the tablet (40a) include Mo, W, and W-Mo alloys, and preferably Mo. The buffer material (40b) is a metal member provided as a buffer to mitigate the difference in thermal expansion between the tablet (40a) and the RF rod (20) and / or the difference in thermal expansion between the tablet (40a) and the heater rod (22), and is provided between the tablet (40a) and the RF rod (20) and / or between the tablet (40a) and the heater rod (22). Preferred examples of the metal constituting the buffer material (40b) include alloys such as Kovar (registered trademark) (Fe-Ni-Co alloy). If the metal member (40) includes a tablet (40a) and a buffer (40b), it is preferable to solder the RF rod (20), the buffer (40b), and the tablet (40a) together using a solder (44) (e.g., Au). Likewise, it is preferable to solder the heater rod (22), the buffer (40b), and the tablet (40a) together using a solder (44) (e.g., Au).

[0073] The eyelet (42) is a metal tubular member that fits into the terminal hole (12c). The eyelet (42) serves to guide the smooth insertion of the RF rod (20) or heater rod (22) into the terminal hole (12c). The eyelet (42) may have a screw cut into it. In this case, the RF rod (20) or heater rod (22) may also have a screw cut into it, allowing the RF rod (20) or heater rod (22) to be inserted by screwing it into the eyelet (42). The metal constituting the eyelet (42) is not particularly limited, but preferred examples include Ni, W, Mo, W-Mo alloy, etc., and preferably Ni. Additionally, a male screw may be cut into the outer circumference of the eyelet (42). By providing a screw portion, the terminal hole (12c) and the eyelet (42) can be screwed together.

[0074] Below, various embodiments employing various RF loads (20) will be described with reference to the drawings.

[0075] (First embodiment)

[0076] The first embodiment is an embodiment in which an RF rod (20) is employed using a gold-plated brass tube for the outer portion (28) and a nickel cable-shaped member for the core portion (26). This embodiment corresponds to the configuration of the ceramic susceptor (10) and RF rod (20) shown in FIGS. 1 to 4. Accordingly, in the first embodiment, the core portion (26) comprises a first rod-shaped member (26a), a second rod-shaped member (26b), and a cable-shaped member (26c) interposed between them, as described above. Additionally, the outer portion (28) includes a tube-shaped portion (30) and a cap portion (32), as described above, and the tube-shaped portion (30) is composed of a single tube-shaped member (30a). Hereinafter, in the present embodiment, the member in which the root portion (24), the first rod-shaped member (26a), the cable-shaped member (26c), and the second rod-shaped member (26b) are connected in sequence shall be referred to as the “Ni cable rod.” The specifications of the RF rod (20) in the first embodiment are as follows.

[0077] <Ni 케이블 로드>

[0078] ㆍSource portion (24): A nickel member having an end portion (24a) and a flange (24b)

[0079] ㆍFirst rod-shaped member (26a): Nickel rod (having a connecting part (27) with an enlarged diameter at the end)

[0080] ㆍSecond rod-shaped member (26b): Nickel rod

[0081] ㆍCable-shaped member (26c): Nickel cable

[0082] <Outsourcing (28)>

[0083] ㆍTubular shape part (30): Brass tube with an outer surface gold-plated (Gold plating thickness: about 10㎛)

[0084] ㆍCap portion (32): A cap portion made of brass with an outer surface gold-plated (gold plating thickness: about 10㎛), having a cap shape that blocks one end of the tube-shaped portion (30).

[0085] ※ For the tube-shaped part (30) and the cap part (32), stainless steel (SUS316) may be used instead of brass.

[0086] In the first embodiment, the installation of the RF rod (20) on the ceramic plate (12) can be performed as follows. First, the source portion (24) (specifically the end portion (24a)) of the Ni cable rod is inserted into the terminal hole (12c) of the ceramic plate (12), and the source portion (24) is soldered to the RF electrode (14) through the connecting member (15). The soldering temperature at this time is approximately 1000°C. At this time, if gold plating is present, the gold will melt and the plating will peel off during soldering, so gold plating cannot be performed on the Ni cable rod in advance. Next, a tube-shaped portion (30), which is a gold-plated brass tube, is placed to accommodate the Ni cable rod inside, and the end of the tube-shaped portion (30) is twisted into the connecting portion (27) of the Ni cable rod. At this time, the position of the end of the tube-shaped portion (30) is determined by being restricted by the flange (24b). By welding the gold-plated brass tube, which is the tubular shape (30) arranged in this way, and the gold-plated brass cap (32) at the joint (34), the cap (32) can be prevented from becoming loose and falling off from the tubular shape (30), and good electrical connection can be secured. In this way, an RF rod (20) having a structure in which the core (26) of the Ni cable rod is covered by the outer periphery (28) (tubular shape (30) and cap (32)) can be obtained. Although brass and nickel have different thermal expansion rates, the difference in thermal expansion rates between the brass constituting the outer periphery (28) and the nickel constituting the core (26) and the base (24) can be absorbed by the cable shape member (26c) (nickel cable). For example, in brass and nickel, a displacement caused by a difference in thermal expansion of about 1 mm occurs over a length of 300 mm, but according to the present embodiment, such a difference in thermal expansion rate and displacement can be effectively absorbed. In addition, in this embodiment, gold plating is applied to the outer surface of the outer periphery (28) (i.e., the tube-shaped part (30) and the cap part (32)), and the technical significance thereof is explained as follows.First, since gold plating on nickel causes gold to diffuse and form an Au-Ni alloy, gold plating on Ni tubes or Ni cable rods must be avoided (i.e., gold-plated Ni tubes cannot be used). Also, since nickel is a ferromagnetic material, it cannot be applied to the outer periphery (28) through which high frequency flows. In this regard, in the present embodiment, gold plating is performed on the outer surface of the brass outer periphery (28) (tube-shaped part (30) and cap part (32)), thereby allowing for the prevention of oxidation of the brass constituting the base of the gold plating and the reduction of impedance due to the paramagnetic material to be preferably realized at a usage temperature of up to about 700°C.

[0087] (Second embodiment)

[0088] The second embodiment is an embodiment in which a gold-plated titanium tube is used for the outer portion (28) and a nickel cable-shaped member is used for the core portion (26) in an RF rod (20). This embodiment also corresponds to the configuration of the ceramic susceptor (10) and RF rod (20) shown in FIGS. 1 to 4, and has the same configuration as the first embodiment except that titanium is used instead of brass for the outer portion (28) as described below.

[0089] <Outsourcing (28)>

[0090] ㆍTubular shape part (30): Titanium tube with an outer surface gold-plated (gold plating thickness: about 10㎛)

[0091] ㆍCap portion (32): A titanium cap portion with an outer surface gold-plated (gold plating thickness: about 10㎛), having a cap shape that blocks one end of the tube-shaped portion (30).

[0092] ※ For the tube-shaped part (30) and the cap part (32), stainless steel (SUS316) may be used instead of titanium.

[0093] In the second embodiment, the installation of the RF rod (20) on the ceramic plate (12) can also be performed in the same manner as in the first embodiment, except that titanium is used instead of brass. Although titanium and nickel have different rates of thermal expansion, the difference in the rate of thermal expansion between the titanium constituting the outer periphery (28) and the nickel constituting the core (26) and the root portion (24) can be absorbed by the cable-shaped member (26c) (nickel cable). For example, in titanium and nickel, a displacement caused by a difference in thermal expansion of about 0.8 mm occurs over a length of 300 mm, but according to the present embodiment, such a difference in the rate of thermal expansion and displacement can be effectively absorbed. In addition, in the present embodiment, gold plating is performed on the outer surface of the outer periphery (28) (i.e., the tube-shaped portion (30) and the cap portion (32)), and the technical significance thereof is explained as follows. First, since gold plating on nickel causes gold to diffuse and form an Au-Ni alloy, gold plating on Ni tubes or Ni cable rods must be avoided (i.e., gold-plated Ni tubes cannot be used). Also, since nickel is a ferromagnetic material, it cannot be applied to the outer periphery (28) through which high frequency is passed. In this regard, in the present embodiment, gold plating is performed on the outer surface of the titanium outer periphery (28) (tube-shaped part (30) and cap part (32)), thereby allowing for the prevention of oxidation of the titanium constituting the base of the gold plating and the reduction of impedance due to the paramagnetic material to be preferably realized at a usage temperature of up to about 700°C.

[0094] (Third embodiment)

[0095] The third embodiment is an embodiment in which an RF rod (20) is employed in which a gold-plated titanium mesh-shaped member is used in the outer portion (28) and a nickel rod-shaped member (not including a cable-shaped member) is used in the core portion (26). This embodiment corresponds to the configuration of the ceramic susceptor (10) and RF rod (20) shown in FIGS. 5 and 6. Accordingly, in the third embodiment, the core portion (26) is provided with a single rod-shaped member (26a). In addition, the outer portion (28) includes a tube-shaped portion (30) and a cap portion (32) as described above, and the tube-shaped portion (30) is composed of a first tube-shaped member (30a), a second tube-shaped member (30b), and a mesh-shaped member (30c) interposed between them. Hereinafter, the integral formed by the root portion (24) and the rod-shaped member (26a) in the present embodiment shall be referred to as the “Ni rod.” The specifications of the RF rod (20) in the third embodiment are as follows.

[0096] <Ni 로드>

[0097] ㆍSource portion (24): A nickel member having an end portion (24a) and a flange (24b)

[0098] ㆍCore part (26) (rod-shaped member (26a)): Nickel rod (having a connecting part (27) with an enlarged diameter at the end)

[0099] <Outsourcing (28)>

[0100] ㆍFirst tube-shaped member (30a): Titanium tube with an outer surface gold-plated (gold plating thickness: approximately 10㎛)

[0101] ㆍSecond tube-shaped member (30b): Titanium tube with an outer surface gold-plated (gold plating thickness: about 10㎛)

[0102] ㆍMesh-shaped member (30c): A mesh sleeve made of titanium, tungsten, or molybdenum with an outer surface gold-plated (50 mesh (wire diameter: 0.12 mm and mesh size: approx. 0.4 mm) or 24 mesh (wire diameter: 0.35 mm and mesh size: approx. 0.7 mm) (gold plating thickness: approx. 10 µm)

[0103] (※ In the case of tungsten or molybdenum mesh, a chrome plating is provided between the mesh and the gold plating. Additionally, in the case of titanium mesh, a TiN layer may be provided between the mesh and the gold plating.)

[0104] ㆍCap portion (32): A titanium cap portion with an outer surface gold-plated (gold plating thickness: about 10㎛), having a cap shape that blocks one end of the tube-shaped portion (30).

[0105] In the third embodiment, the installation of the RF rod (20) on the ceramic plate (12) can be performed as follows. Additionally, the following description is provided for the case where a titanium mesh sleeve with a gold-plated outer surface is used as the mesh-shaped member (30c), but the same applies to the case where a gold-plated tungsten or molybdenum mesh sleeve is used. First, the source portion (24) (particularly the end portion (24a)) of the Ni rod is inserted into the terminal hole (12c) of the ceramic plate (12), and the source portion (24) is soldered to the RF electrode (14) through the connecting member (15). The soldering temperature at this time is approximately 1000°C. At this time, if gold plating is present, the gold melts and the plating peels off during soldering, so gold plating cannot be performed on the Ni rod in advance. Next, a tube-shaped portion (30), which is a gold-plated titanium tube / mesh sleeve composite, is positioned to accommodate a Ni rod inside, and the end of the tube-shaped portion (30) is twisted into the joint portion (27) of the Ni rod. At this time, the end of the tube-shaped portion (30) is positioned by being regulated by a flange (24b). By welding the tube-shaped portion (30) (specifically a gold-plated titanium tube) and the gold-plated titanium cap portion (32) at the joint portion (34), the cap portion (32) can be prevented from becoming loose and falling out of the tube-shaped portion (30), and a good electrical connection can be secured. In this way, an RF rod (20) having a structure in which the core portion (26) of the Ni rod is covered by the outer portion (28) (tube-shaped portion (30) and cap portion (32)) can be obtained. Although titanium and nickel have different rates of thermal expansion, the difference in rates of thermal expansion between the titanium constituting the outer periphery (28) and the nickel constituting the core (26) and root (24) can be absorbed by the mesh-shaped member (30c) (titanium mesh sleeve) (displacement of ±1mm can be absorbed without issue). In addition, in this embodiment, gold plating is applied to the outer surface of the outer periphery (28) (i.e., the tube-shaped part (30) and the cap part (32)), and the technical significance thereof is explained as follows.First, since gold plating on nickel causes the gold to diffuse and form an Au-Ni alloy, gold plating on Ni tubes or Ni cable rods must be avoided (i.e., gold-plated Ni tubes cannot be used). Also, since nickel is a ferromagnetic material, it cannot be applied to the outer part (28) through which high frequency is passed, whereas titanium is a paramagnetic material and is suitable as the outer part (28) through which high frequency is passed. Even so, titanium is an active material and oxidizes immediately in high-temperature regions and deteriorates. In this regard, in the present embodiment, gold plating is performed on the outer surface of the titanium outer part (28) (tube-shaped part (30) and cap part (32)), thereby allowing for the prevention of oxidation of the titanium constituting the base of the gold plating and the reduction of impedance due to the paramagnetic material to be preferably realized at a usage temperature of up to about 700°C.

[0106] (Fourth embodiment)

[0107] The fourth embodiment is a configuration in which a plurality of RF rods (20) are connected, as shown in FIGS. 7 to 9. That is, as described above, a plurality of RF rods (20) are connected by a connecting member (36) made of a non-magnetic material, thereby enabling further reduction of the impedance of the RF rods (20). In this embodiment, two RF rods (20) are connected by a connecting member (36) in the form of a thin plate or mesh made of titanium, brass, or stainless steel (SUS316), with a gold-plated surface. As shown in FIGS. 7 to 9, the connecting member (36) is provided to be suspended from the tubular portion (30) of both RF rods (29), and the portion wound and fixed to the tubular portion (30) of the connecting member (36) forms a thin-walled pipe (36a) with a thickness of 1 mm or less. The thin-walled pipe (36a) is not limited to being wound around the tubular portion (30) of the connecting member (36), but may be pre-formed into a tubular shape so that the tubular portion (30) can be inserted inside. As shown in FIG. 8, it is preferable to place the connecting member (36) over approximately the entire length of the tubular portion (30) from the perspective of low impedance, but it is also acceptable to place the connecting member (36) only in a part of the length of the tubular portion (30). In addition, the connecting member (36) is configured to be caught on the joint portion (34) of the tubular portion (30) and the cap portion (32), and it is preferable to have a configuration in which the connecting member (36) can be welded and fixed simultaneously when welding the joint portion (34).

[0108] In FIGS. 7 to 9, an RF rod (20) with a configuration similar to that of the first or second embodiment is employed, but is not limited thereto, and an RF rod (20) of the third embodiment may also be employed. Accordingly, the installation of a plurality of RF rods (20) on the ceramic plate (12) can be performed in the same manner as the first, second, or third embodiment, except for the placement of the connecting member (36). Furthermore, the connecting member (36) can be fixed to the RF rod (20) by welding the connecting member (36) simultaneously during the welding of the joint (34).

[0109] (Fifth embodiment)

[0110] The fifth embodiment is an embodiment in which an RF rod (20) is used in which a gold-plated titanium tube is used for the outer portion (28) and a titanium rod-shaped member (not including a cable-shaped member) is used for the core portion (26). The RF rod (20) according to the fifth embodiment corresponds to a configuration in which the outer portion (28) of the second embodiment is used as shown in FIG. 10, and the Ni rod of the third embodiment is replaced with a Ti rod. Accordingly, the core portion (26) is provided with a single rod-shaped member (26a) as described above. In addition, the outer portion (28) includes a tubular portion (30) and a cap portion (32) as described above, and the tubular portion (30) is composed of a single tube-shaped member (30a). That is, in the fifth embodiment, a member that absorbs a difference in thermal expansion, such as a cable-shaped member (26c) or a mesh-shaped member (30c), is unnecessary. This is because, since not only the outer part (28) but also the source part (24) and the core part (26) are made of titanium, no difference in thermal expansion rate occurs. The specifications of the RF rod (20) in the fifth embodiment are as follows.

[0111] <Ti 로드>

[0112] ㆍSource portion (24): Titanium member having an end portion (24a) and a flange (24b)

[0113] ㆍCore part (26) (rod-shaped member (26a)): Titanium rod (having a connecting part (27) with an enlarged diameter at the end)

[0114] <Outsourcing (28)>

[0115] ㆍTubular shape part (30): Titanium tube with an outer surface gold-plated (gold plating thickness: about 10㎛)

[0116] ㆍCap portion (32): A titanium cap portion with an outer surface gold-plated (gold plating thickness: about 10㎛), having a cap shape that blocks one end of the tube-shaped portion (30).

[0117] In the fifth embodiment, the installation of the RF rod (20) on the ceramic plate (12) can be performed as follows. First, the source portion (24) of the Ti rod is inserted into the terminal hole (12c) of the ceramic plate (12), and the source portion (24) (specifically the end portion (24a)) is soldered to the RF electrode (14) through a connecting member (15). The soldering temperature at this time is approximately 1000°C. At this time, gold plating cannot be performed on the Ti rod in advance because if gold plating is present, the gold melts and the plating peels off during soldering. Next, a cylindrical portion (30), which is a gold-plated titanium tube, is placed to accommodate the Ti rod inside, and the end of the cylindrical portion (30) is twisted into the connecting portion (27) of the Ti rod. At this time, the position of the end of the cylindrical portion (30) is determined by being restricted by the flange (24b). By welding the gold-plated titanium tube, which is the tubular part (30) arranged in this manner, and the gold-plated titanium cap part (32) at the joint part (34), it is possible to prevent the cap part (32) from becoming loose and falling off the tubular part (30), and at the same time, secure a good electrical connection. In this way, an RF rod (20) having a structure in which the core part (26) of the Ti rod is covered by the outer part (28) (tubular part (30) and cap part (32)) can be obtained. Furthermore, in this embodiment, gold plating is performed on the outer surface of the outer part (28) (i.e., tubular part (30) and cap part (32)), and the technical significance thereof is explained as follows. First, titanium is a paramagnetic material and is suitable as an outer part (28) through which high frequency flows. However, titanium is an active material and immediately oxidizes and deteriorates in high-temperature regions. In this aspect, in the present embodiment, gold plating is applied to the outer surface of the titanium outer periphery (28) (tube-shaped part (30) and cap part (32)), thereby enabling the prevention of oxidation of the titanium constituting the gold plating base and the reduction of impedance by the paramagnetic material at a maximum operating temperature of about 700°C.

Claims

Claim 1 A ceramic susceptor comprising: a disc-shaped ceramic plate having a first surface and a second surface, with an RF electrode and a heater electrode embedded therein; a cylindrical ceramic shaft installed on the second surface of the ceramic plate and having an internal space; an RF rod having one end directly or indirectly connected to the RF electrode and the other end extending protruding from the second surface and extending through the internal space; and a heater rod having one end directly or indirectly connected to the heater electrode and the other end extending protruding from the second surface and extending through the internal space; wherein the RF rod comprises a source portion including an end portion inserted into a terminal hole formed on the second surface of the ceramic plate; a core portion extending from the source portion in a direction away from the second surface; and an outer portion made of a non-magnetic material covering the outer circumference of the core portion. Claim 2 A ceramic susceptor according to claim 1, wherein the non-magnetic material constituting the outer periphery comprises at least one material selected from the group consisting of brass, titanium, stainless steel, chromium, tungsten, molybdenum, and gold. Claim 3 A ceramic susceptor according to claim 1 or 2, wherein the surface of the outer periphery is plated with gold and / or chrome. Claim 4 A ceramic susceptor according to claim 1 or 2, wherein the outer periphery comprises a tube-shaped portion composed of a tube-shaped member and / or a mesh-shaped member formed into a cylindrical shape, and a cap portion that blocks the end opposite to the source portion of the tube-shaped portion. Claim 5 A ceramic susceptor according to claim 1 or 2, wherein the core portion and the source portion comprise nickel or titanium. Claim 6 A ceramic susceptor according to claim 1 or 2, wherein the core portion comprises a rod-shaped member, a cable-shaped member, or a combination thereof. Claim 7 A ceramic susceptor according to claim 1 or 2, wherein the core portion comprises a first rod-shaped member constituting a portion on the root portion side of the core portion, a second rod-shaped member constituting a tip portion on the opposite side of the root portion of the core portion, and a cable-shaped member interposed between the first rod-shaped member and the second rod-shaped member. Claim 8 A ceramic susceptor according to claim 1 or 2, wherein the core portion is composed of a single rod-shaped member. Claim 9 A ceramic susceptor according to claim 1 or 2, wherein the ceramic susceptor comprises a plurality of RF rods, and the plurality of RF rods are connected in the internal space by a connecting member made of a non-magnetic material having at least one shape selected from the group consisting of a mesh shape, a foil shape, and a plate shape. Claim 10 A ceramic susceptor according to claim 9, wherein the non-magnetic material constituting the connecting member comprises at least one selected from the group consisting of brass, titanium, stainless steel, chromium, tungsten, and molybdenum. Claim 11 A ceramic susceptor according to claim 1 or 2, wherein the RF electrode also functions as an ESC electrode.

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