wafer boat

Abstract

The wafer stage 10 is configured such that, inside a ceramic plate 12 having a wafer placement surface 12a on its upper surface, a sub-RF electrode 21 serving as a first conductive layer and a jumper 22 serving as a second conductive layer are disposed at different heights, and a connection portion 23 is provided to electrically connect the sub-RF electrode 21 and the jumper 22. The sub-RF electrode 21, the jumper 22, and the connection portion 23 are a seamless monolithic structure 30.

Description

Technical Field This invention relates to a wafer mounting stage. Background Technology Conventionally, wafer mounting stages are known to have a circular main RF electrode inside a ceramic plate, an annular secondary RF electrode disposed on the outer periphery of the main RF electrode, a rectangular and planar jumper wire positioned below the secondary RF electrode, and a connection portion electrically connecting the secondary RF electrode and the jumper wire. For example, Patent Document 1 also discloses that in this wafer mounting stage, a horizontally placed coil is used as the connection portion. Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2023-87447 Summary of the Invention However, in Patent Document 1, since the coil is used as the connecting part, the parts of the secondary RF electrode and jumper that contact the coil are sometimes deformed due to the coil, or the contact resistance between the secondary RF electrode and the coil, and the contact resistance between the jumper and the coil, varies from person to person. Therefore, it is sometimes difficult to reliably ensure the electrical connection of the secondary RF electrode, the connecting part, and the jumper layer. The present invention was implemented to solve the above-mentioned problems, and its main objective is to stably ensure the electrical connection between two conductive layers with different heights.

[0001] The wafer stage of the present invention comprises a first conductive layer, a second conductive layer with a different height than the first conductive layer, and a connecting portion electrically connecting the first conductive layer and the second conductive layer inside a ceramic plate having a wafer placement surface on its upper surface. The wafer stage is characterized in that... The first conductive layer, the second conductive layer, and the connecting portion are a seamless monolithic structure. In this wafer mounting stage, the first conductive layer, the second conductive layer, and the interconnects form a seamless monolithic structure. Therefore, the connection between the first conductive layer and the interconnects, or between the second conductive layer and the interconnects, will not be interrupted. Thus, a stable electrical connection between the first and second conductive layers, which have different heights, can be ensured. It should be noted that in this specification, "up" and "down" do not indicate an absolute positional relationship, but rather a relative one. Therefore, depending on the orientation of the wafer stage, "up" and "down" become "down" and "up," "left" and "right," or "front" and "back." Furthermore, "seamless monolithic structure" refers to, for example, a structure obtained by cutting and bending a first conductive layer, a second conductive layer, and a connecting portion from a single piece of conductive material.

[0002] The wafer stage of the present invention (the wafer stage described in [1] above) may include: a main RF electrode disposed inside the ceramic plate; a secondary RF electrode serving as the first conductive layer disposed on the outer periphery of the main RF electrode; a jumper serving as the second conductive layer disposed below the secondary RF electrode; a main RF electrode rod electrically connected to the main RF electrode; and a secondary RF electrode rod electrically connected to the jumper. In this wafer stage, the secondary RF electrode, jumper, and connection portion are seamless monolithic structures. Therefore, the connection between the secondary RF electrode and the connection portion, or the connection between the jumper and the connection portion, will not be interrupted. Therefore, the electrical connection between the secondary RF electrode and the jumper portion can be stably ensured.

[0003] In the wafer stage of the present invention (the wafer stage described above [2]), the jumper may have a horizontal conductor disposed at the center of the ceramic plate, and a plurality of first conductive lines extending horizontally and rotationally symmetrically from the outer edge of the conductor. The connecting portion may be a plurality of second conductive lines extending obliquely upward from the plurality of first conductive lines. The secondary RF electrode may be a ring-shaped assembly formed by arranging horizontal conductive arc portions connected to the plurality of second conductive lines along the circumferential direction. Accordingly, even when a monolithic structure is made of a relatively hard conductive material, it can be manufactured relatively easily. In addition, since the plurality of second conductive lines constituting the connecting portion are rotationally symmetrical, the generation of plasma density variations can be suppressed. It should be noted that the term "level" includes not only the case of being perfectly level, but also the case of being level within an acceptable range (e.g., tolerance) (the same applies below).

[0004] In the wafer stage of the present invention (the wafer stage described above [2]), the jumper can be a horizontal conductor disposed at the center of the ceramic plate, the connecting portion can be a plurality of conductive lines extending obliquely upward from the outer edge of the conductor and having rotational symmetry, and the secondary RF electrode can be a ring-shaped assembly formed by arranging horizontal conductive arc portions connected to the plurality of conductive lines along the circumferential direction. Even so, it can be manufactured relatively easily when a monolithic structure is made of a relatively hard conductive material. In addition, since the plurality of conductive lines constituting the connecting portion have rotational symmetry, it is possible to suppress the generation of plasma density variations.

[0005] In the wafer stage of the present invention (the wafer stage described in any one of [2] to [4] above), the boundary between the jumper and the connection portion can be located inside the main RF electrode when viewed from above. Accordingly, the tilt angle of the connection portion can be reduced.

[0006] In the wafer stage of the present invention (the wafer stage described in any one of [2] to [5] above), the boundary between the jumper and the connection portion can be viewed as a valley zigzag line from a top view, and the boundary between the secondary RF electrode and the connection portion can be viewed as a mountain zigzag line from a top view. Accordingly, a monolithic structure can be manufactured relatively easily.

[0007] In the wafer stage of the present invention (the wafer stage described in any one of [2] to [5] above), the boundary between the jumper and the connection portion can be a valley-shaped line when viewed from above, and the boundary between the secondary RF electrode and the connection portion can also be a valley-shaped line when viewed from above. Accordingly, the tilt angle of the connection portion can be reduced.

[0008] The wafer stage of the present invention (the wafer stage described in any one of [2] to [7] above) may have a cylindrical shaft that is joined to the lower surface of the ceramic plate, and the main RF electrode rod and the secondary RF electrode rod may be disposed in the internal space of the cylindrical shaft. In a wafer stage having a cylindrical shaft, it is necessary to dispose the secondary RF electrode rod in the internal space of the cylindrical shaft; therefore, the application of the present invention is of great significance.

[0009] In the wafer stage of the present invention (the wafer stage described in any one of [1] to [8] above), the monolithic structure can be formed of a conductive mesh. Accordingly, when manufacturing the ceramic plate, ceramic powder can easily pass through the monolithic structure in the vertical direction, and thus, the ceramic powder can easily be distributed throughout the whole.

[0010] In the wafer stage of the present invention (the wafer stage described in [3] or [4] above), the conductor of the jumper may have a hole extending in the vertical direction. Accordingly, the area of ​​the jumper is smaller compared to the case without the hole. Attached Figure Description Figure 1 This is a longitudinal cross-sectional view of the wafer stage 10 located in chamber 52. Figure 2 This is a plan view of the chip placement stage 10. Figure 3 This is an explanatory diagram of the single-piece structure 30. Figure 4 This is an explanatory diagram of the single-piece structure precursor 32. Figure 5 This is a manufacturing process diagram of the chip carrier stage 10. Figure 6 This is a longitudinal cross-sectional view of the wafer stage 110. Figure 7 This is a plan view of the chip placement stage 110. Figure 8 This is an explanatory diagram of a single-piece structure 80. Figure 9 This is an explanatory diagram of the precursor 82 of the monolithic structure. Figure 10 This is a longitudinal cross-sectional view of a wafer stage with a built-in resistive heating element 90. Figure 11 This is a longitudinal cross-sectional view of a wafer stage with a built-in resistive heating element 90. Detailed Implementation [First Implementation Method] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. Figure 1 This is a longitudinal cross-sectional view of the wafer stage 10 disposed in chamber 52. Figure 2 This is a plan view of the chip stage 10. Figure 3 This is an explanatory diagram of the monolithic structure 30. Figure 3 (A) in the diagram is a floor plan. Figure 3 (B) in the diagram is the A-A cross-sectional view. Figure 4 This is a plan view of the single-piece structural precursor 32. The wafer stage 10 is used in semiconductor manufacturing equipment, particularly in semiconductor manufacturing equipment that uses plasma to process wafers W, such as... Figure 1 As shown, it is disposed inside the chamber 52 for semiconductor processing. The wafer stage 10 includes: a ceramic plate 12, and a cylindrical shaft 48 attached to the lower surface 12b of the ceramic plate 12. A main RF electrode 20 and a monolithic structure 30 (sub-RF electrode 21, jumper wire 22 and connector 23) are embedded inside the ceramic plate 12. The ceramic plate 12 is a circular plate formed from ceramic materials such as aluminum nitride, silicon carbide, silicon nitride, and aluminum oxide. The ceramic plate 12 has a circular wafer mounting surface 12a on its upper surface. Multiple irregularities (not shown) are formed on the wafer mounting surface 12a by molding. A heat-conducting gas (e.g., He gas) is supplied from the lower surface 12b of the ceramic plate 12 through a gas supply path (not shown) between the recesses on the wafer mounting surface 12a and the wafer W mounted on the wafer mounting surface 12a. The diameter of the ceramic plate 12 is, for example, 320–380 mm. The main RF electrode 20 is a circular plate electrode concentric with the ceramic plate 12, and is arranged parallel to the wafer mounting surface 12a in a manner opposite to the wafer mounting surface 12a. Parallelism includes not only complete parallelism but also parallelism within an acceptable range (e.g., tolerance) (the same applies hereinafter). The main RF electrode 20 is an electrode whose main component is a high-melting-point composite metal containing two or more of Mo, Nb, W, Ta, their carbides, or other materials. The main RF electrode is formed of a metal mesh or perforated metal, but a metal mesh is preferred. The wire diameter of the metal mesh is preferably 0.1 mm or more (e.g., 0.1 to 2 mm). The main component refers to the component with the highest content among the components (the same applies hereinafter). When plasma is generated in the space above the central region of the wafer W mounted on the wafer mounting surface 12a, an RF voltage is applied between the main RF electrode 20 and the upper electrode (the spray head 53 described later). The main RF electrode 20 is electrically connected to a main RF electrode rod 40 inserted into the lower surface 12b of the ceramic plate 12. The main RF electrode rod 40 is configured not to contact the jumper wire 22. The diameter of the main RF electrode 20 is, for example, about 300 mm. The secondary RF electrode 21, jumper 22 and connecting part 23 are a seamless monolithic structure 30. like Figure 1 As shown, the secondary RF electrode 21 is implanted inside the ceramic plate 12 at a position higher than the primary RF electrode 20. The secondary RF electrode 21 is disposed on the outer periphery of the primary RF electrode 20. Figure 2 and Figure 3 As shown, the secondary RF electrode 21 is a ring-shaped assembly formed by arranging multiple horizontal conductive arc portions 21a along a circumferential direction. Adjacent conductive arc portions 21a in the secondary RF electrode 21 are arranged with a small gap between them. However, adjacent conductive arc portions 21a may also be arranged to overlap each other. Figure 2 As shown, the inner diameter of the annular secondary RF electrode 21 is larger than the outer diameter of the main RF electrode 20, and the outer diameter of the annular secondary RF electrode 21 is smaller than the diameter of the ceramic plate 12. The width of the secondary RF electrode 21 is preferably 5 to 40 mm. like Figure 1 As shown, jumper wire 22 is embedded inside the ceramic plate 12 at a position lower than the main RF electrode 20 and the secondary RF electrode 21. Jumper wire 22 is electrically connected to the secondary RF electrode, which is inserted into the lower surface 12b of the ceramic plate 12, by a rod 41. The distance between jumper wire 22 and secondary RF electrode 21 in the height direction is preferably 2 to 20 mm. Figure 2 and Figure 3 As shown, jumper 22 has: in ceramic plate 12 ( Figure 2The circular conductor 22a is disposed in the center of the component, and a plurality of first conductive lines 22b extend from the circular conductor 22a in a horizontal and rotationally symmetrical manner. The circular conductor 22a may have a plurality of holes extending through in the vertical direction. like Figure 1 As shown, the connector 23 electrically connects the secondary RF electrode 21 and the jumper 22. Figure 2 and Figure 3 As shown, the connecting portion 23 is an assembly of multiple second conductive wires 23a. The multiple second conductive wires 23a extend obliquely upwards from the multiple first conductive wires 22b constituting the jumper 22, and are respectively connected to the multiple conductive arc portions 21a constituting the sub-RF electrode 21. The first conductive wires 22b and the second conductive wires 23a, as described later, are connected by a single horizontal conductive wire 26 (…). Figure 4 The first conductive line 22b and the second conductive line 23a are formed by bending. The boundary 24 between them, viewed from above, is a valley fold line. The boundary 24 is located inside the main RF electrode 20. The boundary 25 between the conductive arc portion 21a and the second conductive line 23a, viewed from above, is a mountain fold line. The boundary 25 is located on the inner edge of the sub-RF electrode 21. When the widths of the first conductive line 22b and the second conductive line 23a are too wide, bending is difficult; when the widths are too narrow, the resistance increases. Therefore, it is preferable to consider the balance between these two factors and set the widths of the first conductive line 22b and the second conductive line 23a to be 5–40 mm. The monolithic structure 30 is obtained by cutting and bending a piece of metal mesh material, in which the connected sub-RF electrodes 21, jumper wires 22, and connecting parts 23 are cut. The metal mesh material is, for example, Mo, Nb, W, Ta, their carbides, or a high-melting-point composite metal containing two or more of these. To fabricate the monolithic structure 30, first, a planar metal mesh material is prepared, and a planar monolithic structure precursor 32, in which the sub-RF electrodes 21, jumper wires 22, and connecting parts 23 are connected, is cut from it. Figure 4 As shown, the monolithic structure precursor 32 includes: a circular conductor 22a, a plurality of horizontal conductive lines 26 extending horizontally and rotationally symmetrically from the outer edge of the circular conductor 22a, and a plurality of conductive arc portions 21a connected to the plurality of horizontal conductive lines 26 respectively. Next, each horizontal conductive line 26 of the monolithic structure precursor 32 is folded into a valley fold by a line segment L1 (corresponding to boundary 24). In addition, a mountain fold is formed by a line segment L2 (corresponding to boundary 25) between the conductive arc portion 21a and the horizontal conductive line 26. As a result, the gap between adjacent conductive arc portions 21a narrows, forming a sub-RF electrode 21. Furthermore, the horizontal conductive lines 26 are bent by line segments L1 and L2 to become a first conductive line 22b and a second conductive line 23a, and the sub-RF electrode 21 and the jumper 22 are at different heights. Thus, the monolithic structure 30 is obtained. The cylindrical shaft 48 is formed of the same ceramic material as the ceramic plate 12. The cylindrical shaft 48 is joined to the center of the lower surface 12b of the ceramic plate 12, providing support for the ceramic plate 12. The outer diameter of the cylindrical shaft 48 is smaller than the diameter of the ceramic plate 12. The upper end of the cylindrical shaft 48 is diffusely joined to the ceramic plate 12. A main RF electrode rod 40 and a secondary RF electrode rod 41 are arranged within the internal space of the cylindrical shaft 48. Next, use Figure 5 The manufacturing example of ceramic plate 12 will be explained. Figure 5 This is an explanatory diagram showing the manufacturing process of ceramic plate 12. Figure 5 In the middle, the orientation of ceramic plate 12 is... Figure 1 The ceramic plate 12 is upside down. First, using ceramic powder with an average particle size of several μm to tens of μm, a first ceramic molded body 121 is prepared. Figure 5 (A)). The first ceramic molded body 121 is in the shape of a frustum of a cone with a diameter smaller than that of a circular plate stacked on top of a circular plate, for example, it is obtained by pressing ceramic powder. Next, a circular main RF electrode 20 made of metal mesh is disposed on the uppermost surface (upper surface of the frustum of a cone) of the first ceramic molded body 121. Figure 5 (B) Next, ceramic powder is placed on the main RF electrode 20 and then pressed to form a second ceramic molded body 122 in the shape of a disc on the main RF electrode 20. Figure 5 (C)). The diameter of the second ceramic molded body 122 is smaller than the diameter of the uppermost surface of the first ceramic molded body 121. At this time, ceramic powder enters the mesh opening of the main RF electrode 20. Next, a monolithic structure 30 made of metal mesh is placed on top of the second ceramic molded body 122 with jumper 22 on top. Figure 5 (D)). At this time, the secondary RF electrode 21 contacts the stepped surface of the first ceramic molded body 121. The diameter of the jumper wire 22 is slightly larger than the diameter of the second ceramic molded body 122. Next, ceramic powder is placed on the upper surface (exposed surface) of the first ceramic molded body 121 and the upper surface of the second ceramic molded body 122, and then pressed to form the third ceramic molded body 123. Figure 5 (E)). At this time, ceramic powder enters the mesh opening of the monolithic structure 30 and the mesh opening of the main RF electrode 20. Thus, a circular plate-shaped ceramic laminate 124 is obtained, in which the first to third ceramic moldings 121 to 123 are integrated. The diameter of the ceramic laminate 124 is the same as the diameter of the first ceramic molding 121. The ceramic laminate 124 is then hot-pressed and fired to obtain a ceramic plate 12 ( Figure 5 (F)). The diameter of the obtained ceramic plate 12 is the same as the diameter of the ceramic laminate 124, and the thickness of the ceramic plate 12 is about half the thickness of the ceramic laminate 124. Next, adopt Figure 1 The following describes an example of the use of the chip carrier stage 10. First, a wafer stage 10 is placed inside the chamber 52. Then, the main RF electrode rod 40 is grounded using an integrator 50, and the secondary RF electrode rod 41 is grounded using an integrator 51. A spray head 53 is provided in the chamber 52 opposite to the wafer stage 10. A disc-shaped wafer W is placed on the wafer placement surface 12a of the wafer stage 10. In this state, the interior of the chamber 52 is set to a predetermined vacuum atmosphere (or reduced pressure atmosphere), and while process gas is supplied from the spray head 53, plasma is generated in the space above the wafer W. Specifically, a high-frequency voltage from a high-frequency (RF) power supply 54 is applied to the spray head 53. At the same time, the impedances of the integrator 50 and the integrator 51 are independently controlled. Typically, the plasma density in the space above the main RF electrode 20 is tended to be higher than the plasma density in the space above the secondary RF electrode 21. Therefore, the impedance of the integrator 50 is set higher, and the impedance of the integrator 51 is set lower. Therefore, current flows more easily through the secondary RF electrode 21 compared to the primary RF electrode 20, enabling the plasma density in the space above the primary RF electrode 20 and the space above the secondary RF electrode 21 to be approximately the same. Then, this plasma is used to perform CVD film deposition or etching on the wafer W. Here, the correspondence between the constituent elements of this embodiment and the constituent elements of the present invention is clarified. The ceramic plate 12 of this embodiment corresponds to the ceramic plate of the present invention, the secondary RF electrode 21 corresponds to the first conductive layer, the jumper 22 corresponds to the second conductive layer, and the connecting part 23 corresponds to the connecting part. In the wafer stage 10 described above, the secondary RF electrode 21, jumper 22, and connection portion 23 are a seamless monolithic structure 30. Therefore, the connection between the secondary RF electrode 21 and the connection portion 23, or the connection between the jumper 22 and the connection portion 23, will not be interrupted. Thus, a stable electrical connection between the secondary RF electrode 21 and the jumper 22 can be ensured. Furthermore, the jumper 22 includes a horizontal circular conductor 22a disposed at the center of the ceramic plate 12, and a plurality of first conductive lines 22b extending horizontally and rotationally symmetrically from the outer edge of the circular conductor 22a. The connecting portion 23 consists of a plurality of second conductive lines 23a extending obliquely upward from the plurality of first conductive lines 22b. The sub-RF electrode 21 is a ring-shaped assembly formed by arranging horizontal conductive arc portions 21a connected to the plurality of second conductive lines 23a along the circumferential direction. Therefore, even when the monolithic structure 30 is made of a relatively hard conductive material (e.g., W, Mo), it can be manufactured relatively easily. In addition, since the plurality of second conductive lines 23a constituting the connecting portion 23 are rotationally symmetrical, the generation of plasma density variations can be suppressed. Furthermore, the boundary 24 between the jumper 22 and the connector 23 is located inside the main RF electrode 20 when viewed from above. Therefore, the tilt angle θ of the connector 23 can be adjusted. Figure 3 The angle θ becomes smaller (i.e., flatter). If the tilt angle θ is smaller, it can suppress the occurrence of defects around the connection part 23 during the hot pressing and firing process of the ceramic plate 12 manufacturing process. Furthermore, the boundary 24 between the jumper 22 and the connector 23 appears as a valley zigzag when viewed from above, and the boundary between the secondary RF electrode 21 and the connector 23 appears as a mountain zigzag when viewed from above. Therefore, it is relatively easy to manufacture a monolithic structure 30. Furthermore, the wafer stage 10 includes a cylindrical shaft 48, which is coupled to the lower surface of the ceramic plate 12. The main RF electrode rod 40 and the secondary RF electrode rod 41 are disposed within the internal space of the cylindrical shaft 48. Since the secondary RF electrode rod 41 needs to be disposed within the internal space of the cylindrical shaft 48 in the wafer stage 10, the application of this invention is of great significance. Furthermore, the monolithic structure 30 is formed of a metal mesh (conductive mesh). Therefore, during the manufacturing of the ceramic plate 12, ceramic powder can easily pass through the monolithic structure 30 in the vertical direction, and the ceramic powder can easily be distributed throughout the entire structure. [Second Implementation] The wafer stage 110 of the second embodiment uses a monolithic structure 80 instead of a monolithic structure 30, and is otherwise the same as the wafer stage 10 of the first embodiment. Therefore, the same symbols are used to mark the same components as in the first embodiment, and their descriptions are omitted. Figure 6 This is a longitudinal cross-sectional view of the wafer stage 110. Figure 7 This is a plan view of the chip stage 110. Figure 8 This is an explanatory diagram of a single-piece structure 80. Figure 8 (A) in the diagram is a floor plan. Figure 8 (B) in the diagram is the B-B cross-section view. Figure 9This is a plan view of the precursor 82 of the monolithic structure. The secondary RF electrode 71, jumper 72, and connector 73 are a seamless monolithic structure 80. like Figure 6 As shown, the secondary RF electrode 71 is implanted inside the ceramic plate 12 at a position higher than the primary RF electrode 20. The secondary RF electrode 71 is disposed on the outer periphery of the primary RF electrode 20. Figure 7 and Figure 8 As shown, the secondary RF electrode 71 is a ring-shaped assembly formed by arranging multiple horizontal conductive arc portions 71a along a circumferential direction. Adjacent conductive arc portions 71a in the secondary RF electrode 71 are arranged with a small gap between them. However, adjacent conductive arc portions 71a may also be arranged to overlap each other. Figure 7 As shown, the inner diameter of the annular secondary RF electrode 71 is larger than the outer diameter of the main RF electrode 20, and the outer diameter of the annular secondary RF electrode 71 is smaller than the diameter of the ceramic plate 12. The width of the secondary RF electrode 71 is preferably 5 to 40 mm. like Figure 6 As shown, jumper 72 is embedded inside the ceramic plate 12 at a position lower than the main RF electrode 20 and the secondary RF electrode 71. Jumper 72 is electrically connected to the secondary RF electrode, which is inserted into the lower surface 12b of the ceramic plate 12, by a rod 41. The distance between jumper 72 and secondary RF electrode 71 in the height direction is preferably 2 to 20 mm. Figure 7 and Figure 8 As shown, jumper 72 is used on ceramic plate 12 ( Figure 7 A horizontal circular conductor is disposed in the center of the jumper 72. The jumper 72 has a plurality of holes 72c extending in the vertical direction. Therefore, the area of ​​the jumper 72 is smaller than that of the case without holes 72c. like Figure 6 As shown, the connector 73 electrically connects the secondary RF electrode 71 and the jumper 72. Figure 7 and Figure 8 As shown, the connecting portion 73 is an assembly of multiple conductive wires 73a. The multiple conductive wires 73a extend from the outer edge of the jumper 72 in a rotationally symmetrical manner, pointing obliquely upwards, and are respectively connected to multiple conductive arc portions 71a constituting the sub-RF electrode 71. The boundary 74 between the jumper 72 and the conductive wires 73a is a valley-shaped bend line when viewed from above. The boundary 74 is located inside the main RF electrode 20 when viewed from above. The boundary 75 between the conductive arc portion 71a and the conductive wires 73a is a valley-shaped bend line when viewed from above. The boundary 75 is located on the outer edge side of the sub-RF electrode 71. When the width of the conductive wire 73a is too wide, it is difficult to bend; when the width is too narrow, the resistance increases. Therefore, it is preferable to set the width of the conductive wire 73a to 5–40 mm, taking into account both factors. The monolithic structure 80 is obtained by cutting and bending a piece of metal mesh material, in which the connected sub-RF electrodes 71, jumper wires 72, and connecting parts 73 are cut. The metal mesh material is, for example, Mo, Nb, W, Ta, their carbides, or a high-melting-point composite metal containing two or more of these. To fabricate the monolithic structure 80, first, a planar metal mesh material is prepared, and a planar monolithic structure precursor 82, in which the sub-RF electrodes 71, jumper wires 72, and connecting parts 73 are connected, is cut from it. Figure 9 As shown, the monolithic structure precursor 82 includes: a jumper 72 serving as a circular conductor; multiple conductive lines 73a extending horizontally and rotationally symmetrically from the outer edge of the jumper 72; and multiple conductive arc portions 71a connected to the multiple conductive lines 73a respectively. Next, each conductive line 73a of the monolithic structure precursor 82 is folded into a valley by a line segment L3 (corresponding to a boundary 74). Additionally, a valley fold is formed by a line segment L4 (corresponding to a boundary 75) between the conductive arc portion 71a and the conductive line 73a. As a result, with respect to the multiple conductive arc portions 71a, the gap between adjacent conductive arc portions 71a that are reversed vertically narrows, forming a sub-RF electrode 71. Furthermore, the two ends of the conductive lines 73a are bent by line segments L3 and L4, thereby placing the sub-RF electrode 71 and the jumper 72 at different heights. Based on this, a monolithic structure 80 is obtained. In the manufacturing process of the ceramic plate 12 in the second embodiment, a single-piece structure 80 is used instead of a single-piece structure 30. Otherwise, the manufacturing process is the same as that of the ceramic plate 12 in the first embodiment. In the chip stage 110 described above, the secondary RF electrode 71, jumper 72, and connection portion 73 are a seamless monolithic structure 80. Therefore, the connection between the secondary RF electrode 71 and the connection portion 73, or the connection between the jumper 72 and the connection portion 73, will not be interrupted. Thus, a stable electrical connection between the secondary RF electrode 71 and the jumper 72 can be ensured. Furthermore, the jumper 72 is a horizontal circular conductor disposed at the center of the ceramic plate 12. The connecting portion 73 consists of multiple conductive lines 73a extending obliquely upward from the outer edge of the jumper 72, which is a circular conductor, and exhibiting rotational symmetry. The secondary RF electrode 71 is a ring-shaped assembly formed by arranging horizontal conductive arc portions 71a, each connected to one of the multiple conductive lines 73a, along a circumferential direction. Therefore, even when the monolithic structure 80 is made of a relatively hard conductive material (e.g., W, Mo), it can be manufactured relatively easily. In addition, since the multiple conductive lines 73a constituting the connecting portion 73 are rotationally symmetrical, the generation of uneven plasma density can be suppressed. Furthermore, the boundary 74 between the jumper 72 and the connector 73 is located inside the main RF electrode 20 when viewed from above. Therefore, the tilt angle θ of the connector 73 can be adjusted. Figure 8The angle θ becomes smaller (i.e., flatter). If the tilt angle θ is smaller, it can suppress the occurrence of defects around the connection 73 during the hot pressing and firing process of the ceramic plate 12. Furthermore, the boundary 74 between the jumper 72 and the connector 73 forms a valley-shaped line when viewed from above, as does the boundary between the secondary RF electrode 71 and the connector 73. Therefore, compared to the first embodiment, the tilt angle θ of the connector 73 can be made smaller, and the distance between the connector 73 and the main RF electrode 20 can be made sufficiently large. Furthermore, the wafer stage 110 includes a cylindrical shaft 48, which is coupled to the lower surface of the ceramic plate 12. The main RF electrode rod 40 and the secondary RF electrode rod 41 are disposed within the internal space of the cylindrical shaft 48. Since the secondary RF electrode rod 41 needs to be disposed within the internal space of the cylindrical shaft 48 in the wafer stage 110, the application of this invention is of great significance. Furthermore, the monolithic structure 80 is formed of a metal mesh (conductive mesh). Therefore, during the manufacturing of the ceramic plate 12, ceramic powder can easily pass through the monolithic structure 80 in the vertical direction, and the ceramic powder can easily be distributed throughout the entire structure. [Other Implementation Methods] It should be noted that the present invention is not limited to any of the above embodiments. Of course, as long as it falls within the technical scope of the present invention, it can be implemented in various ways. For example, in the first embodiment described above, such as Figure 10 and Figure 11 As shown, a resistive heating element (heater electrode) 90 can be implanted inside the ceramic plate 12. The resistive heating element 90 is implanted below the main RF electrode 20. Figure 10 This is an example of embedding the resistive heating element 90 below the main RF electrode 20 and the jumper 22. Figure 11 This is an example of embedding the resistive heating element 90 below the main RF electrode 20 and above the jumper 22. Figure 10 and Figure 11 In this embodiment, the same symbols are used to denote the same components as in the first embodiment. The resistive heating element 90 is configured such that, when viewed from above, it extends from one of a pair of terminals through the entire surface wiring on the wafer mounting surface 12a to the other of the pair of terminals. Power supply rods 91 are electrically connected to each of the pair of terminals of the resistive heating element 90. The power supply rods 91 are connected to a heater power supply (not shown). It should be noted that... Figure 11 In this embodiment, the power supply rod 91 is configured not to contact the jumper 22. The resistive heating element 90 is powered by the heater power supply via the power supply rod 91, thereby generating heat to heat the wafer W. Regarding the shape of the resistive heating element 90, examples include spirals, strips, etc. This is also true in the second embodiment. In the first embodiment described above, eight first conductive lines 22b are arranged at equal angular intervals (45° intervals) from the outer edge of the circular conductor 22a in a rotationally symmetrical manner, but this is not particularly limiting. For example, n first conductive lines can be arranged at equal angular intervals ((360 / n)° intervals) from the outer edge of the circular conductor (n is an integer greater than or equal to 2). This is also the case in the second embodiment. In the first embodiment described above, an example is shown where the secondary RF electrode 21 is positioned above the primary RF electrode 20, but this is not a limitation. For example, the secondary RF electrode 21 can be positioned below the primary RF electrode 20, or the secondary RF electrode 71 can be positioned at the same height as the primary RF electrode 20. This is also true in the second embodiment. Industrial availability The wafer stage of the present invention is used, for example, in a semiconductor manufacturing apparatus. Symbol Explanation 10. Wafer stage, 12. Ceramic plate, 12a. Wafer placement surface, 12b. Lower surface, 20. Main RF electrode, 21. Secondary RF electrode, 21a. Conductive arc portion, 22. Jumper wire, 22a. Circular conductor, 22b. First conductive line, 23. Connector, 23a. Second conductive line, 24. Boundary, 25. Boundary, 26. Horizontal conductive line, 30. Monolithic structure, 32. Monolithic structure precursor, 40. Main RF electrode rod, 41. Secondary RF electrode rod, 48. Cylindrical shaft, 50. Integrator, 51. Integrator, 5 2 chambers, 53 spray head, 54 high-frequency power supply, 71 secondary RF electrode, 71a conductive arc portion, 72 jumper wire, 72c hole, 73 connection portion, 73a conductive line, 74 boundary, 75 boundary, 80 monolithic structure, 82 monolithic structure precursor, 90 resistive heating element, 91 power supply rod, 110 wafer stage, 121 first ceramic molding body, 122 second ceramic molding body, 123 third ceramic molding body, 124 ceramic stack, L1, L2, L3, L4 line segments, W wafer.

Claims

1. A wafer placement stage, wherein a first conductive layer, a second conductive layer having a different height than the first conductive layer, and a connecting portion electrically connecting the first conductive layer and the second conductive layer are provided inside a ceramic plate having a wafer placement surface on its upper surface. The wafer stage is characterized in that... The first conductive layer, the second conductive layer, and the connecting portion are a seamless monolithic structure.

2. The wafer stage according to claim 1, characterized in that, The wafer stage includes: The main RF electrode is disposed inside the ceramic plate; As a secondary RF electrode of the first conductive layer, the secondary RF electrode is disposed on the outer peripheral side of the main RF electrode; As a jumper for the second conductive layer, the jumper is positioned below the secondary RF electrode; A main RF electrode rod, which is electrically connected to the main RF electrode; as well as A secondary RF electrode rod is electrically connected to the jumper wire.

3. The wafer stage according to claim 2, characterized in that, The jumper includes a horizontal conductor disposed at the center of the ceramic plate, and a plurality of first conductive lines extending horizontally and rotationally symmetrically from the outer edge of the conductor. The connecting portion consists of multiple second conductive lines extending obliquely upward from the plurality of first conductive lines. The secondary RF electrode is a ring-shaped assembly formed by arranging horizontal conductive arc portions, which are respectively connected to the plurality of second conductive lines, along the circumferential direction.

4. The wafer stage according to claim 2, characterized in that, The jumper wire is a horizontal conductor disposed in the center of the ceramic plate. The connecting portion consists of multiple conductive lines extending obliquely upwards from the outer edge of the conductor and exhibiting rotational symmetry. The secondary RF electrode is a ring-shaped assembly formed by arranging horizontal conductive arc portions connected to the plurality of conductive lines along the circumferential direction.

5. The wafer stage according to any one of claims 2 to 4, characterized in that, The boundary between the jumper and the connection portion is located inside the main RF electrode when viewed from above.

6. The wafer stage according to any one of claims 2 to 4, characterized in that, The boundary between the jumper and the connecting part appears as a valley-shaped line when viewed from above. The boundary between the secondary RF electrode and the connection portion appears as a zigzag line when viewed from above.

7. The wafer stage according to any one of claims 2 to 4, characterized in that, The boundary between the jumper and the connecting part appears as a valley-shaped line when viewed from above. The boundary between the secondary RF electrode and the connection portion appears as a valley-shaped line when viewed from above.

8. The wafer stage according to any one of claims 2 to 4, characterized in that, The wafer stage includes a cylindrical shaft that engages with the lower surface of the ceramic plate. The main RF electrode rod and the secondary RF electrode rod are disposed in the internal space of the cylindrical shaft.

9. The wafer stage according to any one of claims 1 to 4, characterized in that, The monolithic structure is formed from a conductive mesh.

10. The wafer stage according to claim 3 or 4, characterized in that, The conductor of the jumper has a through hole running vertically.

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