Wafer mounting table

Abstract

A wafer mounting table according to the present disclosure comprises: a ceramic plate having a wafer mounting surface on the upper surface thereof and incorporating an electrode; a plug placement hole extending from the lower surface to the upper surface of the ceramic plate; a plug disposed in the plug placement hole and configured to allow gas to pass therethrough; and a resin plug joint that joins the upper surface outer edge of the plug and the upper opening edge of the plug placement hole and is provided so as to cover the upper surface outer edge of the plug from above.

Description

Wafer mounting table

[0001] The present invention relates to a wafer mounting table.

[0002] Conventionally, wafer mounting tables are used in semiconductor manufacturing apparatuses. For example, the wafer mounting table disclosed in Patent Document 1 has a plug through which gas can pass arranged in a plug arrangement hole extending from the lower surface to the upper surface of a ceramic plate. This wafer mounting table has a plug joint that joins the outer edge of the upper surface of the plug and the upper opening edge of the plug arrangement hole. The plug joint is provided so as to cover the outer edge of the upper surface of the plug from above. The plug joint is formed by filling a groove formed by a plug inclined surface provided on the outer edge of the upper surface of the plug and an arrangement hole inclined surface provided on the upper opening edge of the plug arrangement hole with a ceramic material by thermal spraying. In this wafer mounting table, since the plug joint is provided so as to catch on the upper outer edge of the plug, the plug is prevented from coming out upward from the plug arrangement hole.

[0003] International Publication No. 2024 / 180611 Pamphlet

[0004] However, when the plug joint is formed in a raised shape, it has not been easy to remove the raised portion of the plug joint formed of the ceramic material. Further, although the ceramic plate may warp, the plug joint formed of the ceramic material does not follow the warp, so there has also been a risk that the plug joint may come off.

[0005] The present invention has been made to solve such problems, and a main object of the present invention is to enable easy adjustment of the height of a plug joint, and to prevent the plug joint from easily coming off even if warpage occurs in a ceramic plate.

[0006] [1] The wafer mounting stage of the present invention comprises: a ceramic plate having a wafer mounting surface on its upper surface and containing electrodes; a plug placement hole extending from the lower surface to the upper surface of the ceramic plate; a plug placed in the plug placement hole and through which gas can pass; and a resin plug joint that joins the upper outer edge of the plug with the upper opening edge of the plug placement hole and covers the upper outer edge of the plug from above.

[0007] In this wafer mounting stage, a plug through which gas can pass is placed in a plug placement hole. The upper outer edge of the plug and the upper opening edge of the plug placement hole are joined by a plug joint. The plug joint is positioned to cover the upper outer edge of the plug from above. Because the plug joint is positioned to catch on the upper outer edge of the plug, it prevents the plug from coming out upward from the plug placement hole. Furthermore, if the height of the plug joint needs to be adjusted, it can be adjusted relatively easily because the plug joint is made of resin. In addition, even if the ceramic plate warps, the resin plug joint will follow the warp and is less likely to come off.

[0008] In this specification, the present invention may be described using terms such as up and down, left and right, front and back, but up and down, left and right, and front and back are merely relative positional relationships. Therefore, if the orientation of the wafer mounting stage is changed, up and down may become left and right, or left and right may become up and down, but such cases are also included within the technical scope of the present invention. In this specification, the numerical range a to b means a or greater and b or less.

[0009] [2] In the wafer mounting stage of the present invention (the wafer mounting stage described in [1] above), the resin may contain a filler. In this case, if the plug joint has a raised shape, the raised portion can be scraped off relatively easily.

[0010] [3] In the wafer mounting stage of the present invention (the wafer mounting stage described in [2] above), the resin may contain 80 to 90% by mass of the filler. This makes it easier to scrape off the raised portion of the plug joint while maintaining the adhesive strength of the plug joint.

[0011] [4] In the wafer mounting stand of the present invention (the wafer mounting stand described in any of [1] to [3] above), the upper outer edge of the plug may be provided with a plug inclined surface, the upper opening edge of the plug placement hole may be provided with a placement hole inclined surface, and the plug joint portion may be provided so as to fill the groove formed by the plug inclined surface and the placement hole inclined surface. In this way, the plug joint portion can be formed relatively easily. The inclined surface may be a flat surface or a curved surface (concave or convex).

[0012] [5] In the wafer mounting stand of the present invention (the wafer mounting stand described in [4] above), the angle between the arrangement hole inclined surface and the plug inclined surface may be 30 to 60°. If this angle is less than 30°, it may be difficult to fill the groove with resin, and if it exceeds 60°, the plug joint may affect the gas flow passing through the plug, but if it is between 30 and 60°, there is little to no such risk.

[0013] [6] In the wafer mounting stage of the present invention (the wafer mounting stage described in [4] or [5] above), the angle that the arrangement hole inclined surface makes with the horizontal plane may be smaller than the angle that the plug inclined surface makes with the horizontal plane. This increases the contact area between the arrangement hole inclined surface and the plug joint, resulting in good bonding between the arrangement hole inclined surface and the plug joint.

[0014] [7] In the wafer mounting stage of the present invention (the wafer mounting stage described in any of [4] to [6] above), the arithmetic mean roughness Ra of the placement hole inclined surface may be greater than the arithmetic mean roughness Ra of the plug inclined surface. This increases the contact area between the placement hole inclined surface and the plug joint, resulting in better bonding between the placement hole inclined surface and the plug joint.

[0015] [8] The wafer mounting stand of the present invention (the wafer mounting stand described in any of [1] to [7] above) may further include a conductive plate bonded to the lower surface of the ceramic plate and provided with a gas supply passage communicating with the plug placement hole. The conductive plate may be used as a cooling plate to cool the ceramic plate, or as a high-frequency electrode for generating plasma above the wafer mounting surface. In this case, the upper surface of the ceramic plate is not constrained, but the lower surface of the ceramic plate is constrained, making the ceramic plate prone to warping. Therefore, there is great significance in applying the present invention.

[0016] A longitudinal cross-sectional view of the wafer mounting table 10. A plan view of the ceramic plate 20. A partial enlarged view of Figure 1. A plan view of the area around the plug joint 60. A manufacturing process diagram of the wafer mounting table 10. An explanatory diagram showing the procedure for adjusting the height of the plug joint 60. A plan view of the area around the intermittently provided plug joints 60. A longitudinal cross-sectional view (schematic diagram) of the plug 55. A longitudinal cross-sectional view of the wafer mounting table 110.

[0017] This embodiment will be described with reference to the drawings. Figure 1 is a longitudinal cross-sectional view of the wafer mounting stage 10, Figure 2 is a plan view of the ceramic plate 20, Figure 3 is a partially enlarged view of Figure 1, and Figure 4 is a plan view of the area around the plug joint 60.

[0018] The wafer mounting stage 10 comprises a ceramic plate 20, plug placement holes 24, a base plate (conductive plate) 30, a metal bonding layer 40, a plug 50, and a plug bonding portion 60.

[0019] The ceramic plate 20 is a ceramic disc (for example, 300 mm in diameter and 5 mm thick) made of an alumina sintered body or an aluminum nitride sintered body. A wafer mounting surface 21 is provided on the upper surface of the ceramic plate 20. The ceramic plate 20 incorporates electrodes 22. As shown in Figure 2, a sealing band 21a is formed along the outer edge of the upper surface of the ceramic plate 20, and a plurality of small circular protrusions 21b are formed on the entire surface. The sealing band 21a and the small circular protrusions 21b are of the same height, for example, several μm to several tens of μm. The electrodes 22 are planar mesh electrodes used as electrostatic electrodes, and a DC voltage can be applied to them. When a DC voltage is applied to these electrodes 22, the wafer W is adsorbed and fixed to the wafer mounting surface 21 (specifically, the upper surface of the sealing band 21a and the upper surface of the small circular protrusions 21b) by electrostatic adsorption force, and when the application of the DC voltage is removed, the adsorption and fixation of the wafer W to the wafer mounting surface 21 is released. The portion of the upper surface of the ceramic plate 20 that does not have the sealing band 21a or the small circular protrusions 21b is referred to as the reference surface 21c.

[0020] The plug placement hole 24 is a hole that extends from the bottom surface to the top surface of the ceramic plate 20, in this case a through hole that penetrates the ceramic plate 20 in the vertical direction. The plug placement hole 24 is opposite the gas hole 34 of the base plate 30. The plug placement hole 24 penetrates the electrode 22 in the vertical direction, but the electrode 22 is not exposed on the inner circumferential surface of the plug placement hole 24. The plug placement hole 24 is a tapered hole having a frustoconical space in which the area of ​​the upper opening is larger than the area of ​​the lower opening. As shown in Figure 3, the upper opening edge of the plug placement hole 24 is chamfered all around to form a placement hole inclined surface 24c. The placement hole inclined surface 24c is a flat surface, not a curved surface. As shown in Figure 2, the plug placement holes 24 are provided at multiple locations on the ceramic plate 20 (for example, at multiple locations provided at equal intervals along the circumferential direction).

[0021] The base plate 30 is a conductive disc with good thermal conductivity (a disc with the same diameter as or larger than the ceramic plate 20). Inside the base plate 30, a refrigerant channel 32 through which a refrigerant (for example, an electrically insulating liquid such as a fluorine-based inert liquid) circulates and a gas hole 34 for supplying gas to the plug 50 are formed. The gas hole 34 is provided to penetrate the base plate 30 in the vertical direction and has a large-diameter portion 34a at the top. In a plan view, the large-diameter portion 34a encloses the lower opening of the plug placement hole 24. In a plan view, the refrigerant channel 32 is formed in a continuous line from the inlet to the outlet across the entire surface of the base plate 30. Examples of materials for the base plate 30 include metal and composite materials. Examples of metals include Mo. Examples of composite materials include composite materials of metal and ceramic. Examples of composite materials of metals and ceramics include metal matrix composites (MMCs) and ceramic matrix composites (CMCs). Specific examples of such composite materials include materials containing Si, SiC, and Ti, and materials in which Al and / or Si are impregnated into a porous SiC body. Materials containing Si, SiC, and Ti are called SiSiCTi, materials in which Al is impregnated into a porous SiC body are called AlSiC, and materials in which Si is impregnated into a porous SiC body are called SiSiC. It is preferable to select a base plate 30 material with a thermal expansion coefficient similar to that of the ceramic plate 20. The base plate 30 is also used as an RF electrode. Specifically, an upper electrode (not shown) is placed above the wafer mounting surface 21, and plasma is generated when high-frequency power is applied between the upper electrode and the base plate 30, which are parallel plate electrodes.

[0022] The metal bonding layer 40 joins the lower surface of the ceramic plate 20 to the upper surface of the base plate 30. The metal bonding layer 40 is formed, for example, by TCB (Thermal Compression Bonding). TCB is a known method in which a metal bonding material is sandwiched between two members to be joined, and the two members are pressurized and joined while heated to a temperature below the solidus temperature of the metal bonding material. The metal bonding layer 40 may also be a layer formed of solder or metal brazing material. The metal bonding layer 40 has through holes 42. The through holes 42 are provided at a position opposite the large diameter portion 34a of the gas hole 34. The through holes 42 are provided coaxially with the large diameter portion 34a, and the diameter of the through holes 42 is the same as the diameter of the large diameter portion 34a. In this specification, "agree" includes not only cases where they are perfectly aligned, but also cases where they are substantially aligned (for example, within tolerance) (the same applies hereinafter).

[0023] The plug 50 is positioned in the plug placement hole 24. The plug 50 is an electrically insulating member that allows gas to flow in the vertical direction. Here, the plug 50 is a porous ceramic body, and for example, a porous body made of the same material as the ceramic plate 20 can be used. The porosity of the plug 50 is preferably 30% or more, and the average pore diameter is preferably 20 μm or more. As shown in Figure 3, the outer edge of the upper surface of the plug 50 is chamfered all around to form a plug inclined surface 50c. The plug inclined surface 50c is a flat surface, not a curved surface. The plug 50 is a frustoconical member in which the area of ​​the upper surface is larger than the area of ​​the lower surface. Therefore, the plug 50 will not come out downward from the plug placement hole 24. The upper surface 50a of the plug 50 is exposed to the upper opening of the plug placement hole 24 and is coplanar with the reference surface 21c. In this specification, "identical" includes not only cases where they are completely identical, but also cases where they are substantially identical (for example, cases where they fall within tolerance) (the same applies hereinafter). The plug 50 and the plug placement hole 24 are designed such that when the plug 50 is inserted into the plug placement hole 24 and the outer surface of the plug 50 is aligned with the inner surface of the plug placement hole 24, the height of the upper surface 50a of the plug 50 matches the height of the reference surface 21c of the ceramic plate 20. Therefore, the upper surface 50a of the plug 50 and the reference surface 21c of the ceramic plate 20 can be easily made coplanar. The height of the lower surface 50b of the plug 50 may be the same as the height of the lower surface of the ceramic plate 20, or it may be higher or lower.

[0024] The plug joint 60 connects the upper outer edge of the plug 50 to the upper opening edge of the plug placement hole 24, and is provided to cover the upper outer edge of the plug 50 and the upper opening edge of the plug placement hole 24 from above. Here, the plug joint 60 is made by filling a groove formed by the plug inclined surface 50c provided around the entire circumference of the upper outer edge of the plug 50 and the placement hole inclined surface 24c provided around the entire circumference of the upper opening edge of the plug placement hole 24 with resin. The inclined surfaces 24c and 50c are flat surfaces, not curved surfaces. This groove is ring-shaped in plan view and has a V-shaped cross-section. Therefore, as shown in Figure 4, the plug joint 60 is provided in a ring shape around the entire circumference of the upper surface 50a of the plug 50 in plan view. Both the plug inclined surface 50c and the placement hole inclined surface 24c are covered from above by the plug joint 60. The upper surface of the plug joint 60 is at the same height as the upper surface 50a of the plug 50 and the reference surface 21c of the ceramic plate 20. However, the height of the upper surface of the plug joint 60 may protrude from the reference surface 21c, or it may be slightly recessed from the reference surface 21c, as long as it does not exceed the height of the upper surface of the small circular projection 21b.

[0025] The angle θ (Figure 3) between the inclined surface 50c of the plug that forms the groove and the inclined surface 24c of the placement hole is not particularly limited, but is preferably 30 to 60°. If this angle θ is less than 30°, it may become difficult to fill the groove with resin (for example, air bubbles in the resin may not be removed). If this angle θ exceeds 60°, it may affect the flow of gas passing through the plug 50 in the vertical direction. The resin used to fill the groove preferably contains a filler. Examples of resins include silicone resin, epoxy resin, and phenolic resin, but silicone resin is preferred. An insulating inorganic filler is preferred as the filler, and examples of such materials include aluminum oxide and aluminum nitride. The shape of the filler is not particularly limited, but examples include fibrous, columnar, spherical, and plate-shaped fillers. Among these, high aspect ratio shapes such as fibrous and columnar shapes are preferred because they are expected to have a high thermal conductivity effect. The filler content is preferably 80 to 90% by mass. The angle α (Figure 3) that the inclined surface 24c of the placement holes makes with the horizontal plane is preferably smaller than the angle β (Figure 3) that the inclined surface 50c of the plug makes with the horizontal plane. The arithmetic mean roughness Ra of the inclined surface 24c of the placement holes is preferably larger than the arithmetic mean roughness Ra of the inclined surface 50c. If a resin containing filler is used, for example, one with an elongation at break of 50 to 300% and a tensile strength of 2.0 to 6.0 MPa, it will be easier to follow the warping of the ceramic plate if it warps.

[0026] Next, an example of using the wafer mounting stand 10 configured in this way will be described. First, with the wafer mounting stand 10 installed in a chamber (not shown), the wafer W is placed on the wafer mounting surface 21. Then, the pressure inside the chamber is reduced using a vacuum pump to adjust to a predetermined vacuum level, and a DC voltage is applied to the electrode 22 of the ceramic plate 20 to generate electrostatic adsorption force, thereby adsorbing and fixing the wafer W to the wafer mounting surface 21 (specifically, the upper surface of the seal band 21a and the upper surface of the circular protrusion 21b). Next, the inside of the chamber is made into a reaction gas atmosphere with a predetermined pressure (for example, several tens to several hundreds of Pa), and in this state, a high-frequency voltage is applied between an upper electrode (not shown) provided on the ceiling of the chamber and the base plate 30 of the wafer mounting stand 10 to generate plasma. The surface of the wafer W is treated by the generated plasma. A refrigerant is circulated in the refrigerant channel 32 of the base plate 30. Backside gas is introduced into the gas hole 34 from a gas cylinder (not shown). A thermal conductive gas (for example, helium) is used as the backside gas. The backside gas is supplied and sealed into the space between the back surface of the wafer W and the reference surface 21c of the ceramic plate 20 through the gas holes 34, through holes 42, and plug 50. The presence of this backside gas allows for efficient heat conduction between the wafer W and the ceramic plate 20.

[0027] Next, a manufacturing example of the wafer mounting table 10 will be described based on Figure 5. Figure 5 is a manufacturing process diagram of the wafer mounting table 10. First, a ceramic plate 20, a base plate 30, and a metal bonding material 90 are prepared (Figure 5A). The ceramic plate 20 has an electrode 22 built in and is provided with a plug placement hole 24. The upper opening edge of the plug placement hole 24 is chamfered to form a placement hole inclined surface 24c. The base plate 30 is provided with a refrigerant flow path 32 and a gas hole 34. The gas hole 34 has a large diameter portion 34a at the top. The metal bonding material 90 is provided with a through hole 92 at a position opposite to the large diameter portion 34a of the gas hole 34.

[0028] Next, a metal bonding material 90 is sandwiched between the lower surface of the ceramic plate 20 and the upper surface of the base plate 30 to form a laminate. At this time, the laminate is stacked so that the plug placement holes 24 of the ceramic plate 20, the through holes 92 of the metal bonding material 90, and the gas holes 34 of the base plate 30 are coaxial. The laminate is then pressed and bonded at a temperature below the solidus temperature of the metal bonding material 90 (for example, between a temperature 20°C below the solidus temperature and the solidus temperature), and then returned to room temperature (TCB). As a result, the metal bonding material 90 and the through holes 92 become the metal bonding layer 40 and the through holes 42, respectively, and a bonded body 94 is obtained in which the ceramic plate 20 and the base plate 30 are bonded by the metal bonding layer 40 (Figure 5B). As the metal bonding material 90, Al-Mg-based bonding material or Al-Si-Mg-based bonding material can be used. It is preferable to use a metal bonding material 90 with a thickness of about 100 μm.

[0029] Next, a frustoconical plug 50 is prepared (Figure 5B). The outer edge of the upper surface of the plug 50 is chamfered to form a plug inclined surface 50c. Next, the plug 50 is inserted into the plug placement hole 24 (Figure 5C). Then, the plug inclined surface 50c of the plug 50 and the placement hole inclined surface 24c of the plug placement hole 24 form a groove 70 that is ring-shaped in plan view and has a V-shaped cross-section.

[0030] Next, a seal band 21a and small circular protrusions 21b are provided on the upper surface of the ceramic plate 20. Then, the groove 70 is filled with a thermosetting resin, and the thermosetting resin is heated to harden it. As a result, the groove 70 is filled with a resin plug joint 60 (Figure 5D). The plug inclined surface 50c and the placement hole inclined surface 24c are covered from above by the plug joint 60. The thermosetting resin preferably contains a filler. Examples of thermosetting resins include silicone resin, epoxy resin, and phenolic resin, but silicone resin is preferred. The filler has already been described. The filler content is preferably 80 to 90% by mass. Finally, if there is a raised portion 60a on the plug joint 60 (Figure 6A), the raised portion 60a is rubbed off with a jig Z (e.g., a cotton swab) to make the upper surface of the plug joint 60 coincide with the reference surface 21c (Figure 6B). This prevents the plug joint 60 from lifting the wafer W placed on the wafer mounting surface 21.

[0031] Alternatively, before providing the seal band 21a and circular small protrusions 21b on the upper surface of the ceramic plate 20, the groove 70 may be filled with thermosetting resin to form the plug joint 60.

[0032] In the wafer mounting table 10 described in detail above, a plug 50 through which gas can pass is placed in the plug placement hole 24. The upper outer edge of the plug 50 and the upper opening edge of the plug placement hole 24 are joined by a plug joint 60. The plug joint 60 is provided so as to cover the upper outer edge of the plug 50 from above, thereby preventing the plug 50 from coming out upward from the plug placement hole 24. In this way, the plug 50 can be prevented from coming out upward from the plug placement hole 24 with a simple structure in which the upper outer edge of the plug 50 is covered from above by the plug joint 60. Furthermore, if the height of the plug joint 60 needs to be adjusted, it can be adjusted relatively easily because the plug joint 60 is made of resin. Moreover, even if the ceramic plate 20 warps, the resin plug joint 60 follows the warping and is therefore less likely to come off.

[0033] Furthermore, it is preferable that the resin constituting the plug joint 60 contains a filler. This allows the raised portion of the plug joint 60 to be scraped off relatively easily if it has a raised shape (Figure 6). The filler content is preferably 80 to 90% by mass. This makes it easier to scrape off the raised portion of the plug joint 60 while maintaining the adhesive strength of the plug joint 60.

[0034] Furthermore, the plug joint 60 is formed by filling the groove 70, which is formed by the inclined surface 50c of the plug and the inclined surface 24c of the placement hole, with resin. Therefore, the plug joint 60 can be formed relatively easily.

[0035] Furthermore, the angle θ (Figure 3) between the inclined surface 24c of the placement hole and the inclined surface 50c of the plug is preferably 30 to 60°. If this angle θ is less than 30°, it may become difficult to fill the groove with resin (for example, it may be impossible to remove air bubbles in the resin), and if it exceeds 60°, the plug joint 60 may affect the gas flow passing through the plug 50. However, if the angle is between 30 and 60°, there is little to no risk of such an effect.

[0036] Furthermore, it is preferable that the angle α (Figure 3) that the inclined surface 24c of the placement hole makes with the horizontal plane is smaller than the angle β (Figure 3) that the inclined surface 50c of the plug makes with the horizontal plane. This increases the contact area between the inclined surface 24c of the placement hole and the plug joint 60, resulting in better bonding between the inclined surface 24c of the placement hole and the plug joint 60. Even if the plug joint 60 comes off the plug 50, the connection between the plug joint 60 and the plug placement hole 24 is maintained, preventing the plug 60 from coming out upward from the plug placement hole 24.

[0037] Furthermore, it is preferable that the arithmetic mean roughness Ra of the placement hole inclined surface 24c is greater than the arithmetic mean roughness Ra of the plug inclined surface 50c. This increases the contact area between the placement hole inclined surface 24c and the plug joint 60, resulting in better bonding between the placement hole inclined surface 24c and the plug joint 60. Even if the plug joint 60 comes off the plug 50, the connection between the plug joint 60 and the plug placement hole 24 is maintained, preventing the plug 60 from coming out upward from the plug placement hole 24.

[0038] Furthermore, since the upper surface of the ceramic plate 20 is not restrained and the lower surface of the ceramic plate 20 is restrained by the base plate 30, the ceramic plate 20 tends to warp upwards when heated. However, even in such cases, the resin plug joint 60 follows the warping and is therefore less likely to come loose.

[0039] Furthermore, since the plug joint portion 60 is provided around the entire circumference of the plug 50, the bonding strength of the plug joint portion 60 is increased.

[0040] It goes without saying that the present invention is not limited in any way to the embodiments described above, and can be implemented in various forms as long as they fall within the technical scope of the present invention.

[0041] In the embodiment described above, the plug joint portion 60 is provided in a ring shape around the entire circumference of the upper surface 50a of the plug 50 in a plan view, as shown in Figure 4, but it is not limited to this. For example, the plug joint portion 60 may be provided intermittently at two or more locations (four locations in this case) along the circumferential direction of the upper surface 50a of the plug 50 in a plan view, as shown in Figure 7. In this case, although the joint strength will be slightly lower compared to the embodiment described above, sufficient strength for practical use can be obtained. In addition, since the circumferential length of the raised portion 60a of the plug joint portion 60 is shortened, the burden of height adjustment work is reduced.

[0042] In the embodiment described above, a porous plug 50 was exemplified, but the invention is not limited to this, and any electrically insulating material that allows gas to flow vertically may be used. For example, instead of plug 50, plug 55 shown in Figure 8 may be used. Plug 55 has an insulating, dense plug body 56 and a gas passage 57 that penetrates from the lower part (in this case, the bottom surface) of the plug body 56 and opens to the upper surface. As the plug body 56, for example, a dense material made of the same material as the ceramic plate 20 can be used. As the gas passage 57, first to eighth gas passages 57c to 57j are provided here. The first to eighth gas passages 57c to 57j are passages that allow gas to flow, and are provided so as to extend from a lower opening on the bottom surface of the plug body 56 to an upper opening on the top surface. The first to fourth gas passages 57c to 57f are formed in a spiral shape so as to rotate clockwise from top to bottom, with a flat, rectangular cross-section passage. The first to fourth gas passages 57c to 57f are located near the central axis of the plug body 56, offset by 90° along the circumferential direction. The fifth to eighth gas passages 57g to 57j are formed in a spiral shape, with a flat, rectangular cross-section and a band-shaped passage that rotates counterclockwise from top to bottom. The fifth to eighth gas passages 57g to 57j are located further outward than the first to fourth gas passages 57c to 57f, offset by 90° along the circumferential direction. When viewed from above, a portion of each gas passage 57 (the first to eighth gas passages 57c to 57j) is exposed as a recess on the surface, preventing a clear view of the lower opening. In Figure 8, the shape of the first to eighth gas passages 57c to 57j is shown as a spiral shape (an example of a curved shape), but other curved shapes (such as a zigzag shape) are also acceptable. Furthermore, although the first to eighth gas passages 57c to 57j are provided as gas passages 57, they are not limited to eight and any number of passages (even just one) are acceptable. The fifth to eighth gas passages 57g to 57j on the outer periphery may be omitted, as may the fifth to eighth gas passages 57g to 57j on the central side. In addition, the cross-section of each gas passage 57c to 57j may be circular or elliptical.

[0043] In the embodiment described above, the base plate 30 is provided with the gas holes 34 that constitute the gas supply path, but the present invention is not particularly limited to this. For example, as shown in the wafer mounting table 110 of Fig. 9, the base plate 30 may be provided with a ring portion 64a concentric with the base plate 30 in a plan view, an introduction portion 64b that introduces gas from the back surface of the base plate 30 to the ring portion 64a, and a distribution portion 64c that distributes gas from the ring portion 64a to each of the plugs 50. In Fig. 9, the same reference numerals are assigned to the same constituent elements as those in the first embodiment described above. The number of the introduction portions 64b is smaller than the number of the distribution portions 64c, and may be one, for example. With this configuration, the number of external gas pipes connected to the lower surface of the base plate 30 can be made smaller than the number of the plugs 50.

[0044] In the embodiment described above, when removing the raised portion of the plug joint 60, processing is performed such that the upper surface of the plug joint surface 60 matches the reference surface 21c. However, processing may be performed such that the upper surface of the plug joint surface 60 is at the same height as or lower than the upper surface of the small circular projection 21b. Even with this configuration, it is possible to avoid a situation where the plug joint 60 lifts the wafer W mounted on the wafer mounting surface 21.

[0045] In the embodiment described above, the outer peripheral surface of the plug 50 and the inner peripheral surface of the plug arrangement hole 24 may be brought into close contact with each other. With this configuration, an effect of suppressing discharge from occurring between the outer peripheral surface of the plug 50 and the inner peripheral surface of the plug arrangement hole 24 during plasma generation can be obtained. For example, the plug 50 may be press-fitted into the plug arrangement hole 24 to bring the outer peripheral surface of the plug 50 and the inner peripheral surface of the plug arrangement hole 24 into close contact with each other. Alternatively, the outer peripheral surface of the plug 50 and the inner peripheral surface of the plug arrangement hole 24 may be bonded with an adhesive.

[0046] In the embodiment described above, C-chamfering is performed on the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug placement hole 24, but the present invention is not particularly limited to C-chamfering. For example, R-chamfering may be performed. In this case, each of the inclined surfaces 24c and 50c becomes a curved surface (convex surface). In addition, in the state before forming the plug joint 60 (FIG. 5C), the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug placement hole 24 form a groove 70 having a V-shaped cross-section, but the present invention is not particularly limited thereto. For example, the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug placement hole 24 may be processed such that the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug placement hole 24 form a groove having a U-shaped cross-section. In this case, the cross-section of the plug joint 60 has a substantially rectangular shape.

[0047] In the embodiment described above, the truncated cone-shaped plug 50 is exemplified, but the present invention is not particularly limited thereto. For example, a cylindrical plug may be used.

[0048] In the embodiment described above, a stepped hole having a large-diameter portion 34a above the gas hole 34 is employed, but the present invention is not particularly limited thereto. For example, a straight-shaped hole may be employed as the gas hole 34.

[0049] In the embodiment described above, an electrostatic electrode is exemplified as the electrode 22 incorporated in the ceramic plate 20, but the present invention is not particularly limited thereto. For example, instead of or in addition to the electrode 22, a heater electrode (resistance heating element) may be incorporated in the ceramic plate 20, or an RF electrode may be incorporated therein.

[0050] In the embodiment described above, the ceramic plate 20 and the base plate 30 are joined via the metal bonding layer 40, but a resin adhesive layer may be used instead of the metal bonding layer 40.

[0051] The present application claims priority from Japanese Patent Application No. 2025-052806 filed on March 27, 2025, the entire content of which is incorporated herein by reference.

[0052] The present invention is applicable to wafer mounting tables used in semiconductor manufacturing apparatuses, such as ceramic heaters, electrostatic chuck heaters, and electrostatic chucks.

[0053] 10 Wafer mounting platform, 20 Ceramic plate, 21 Wafer mounting surface, 21a Seal band, 21b Small circular protrusion, 21c Reference surface, 22 Electrode, 24 Plug placement hole, 24c Placement hole inclined surface, 30 Base plate, 32 Refrigerant flow path, 34 Gas hole, 34a Large diameter section, 40 Metal bonding layer, 42 Through hole, 50 Plug, 50a Top surface, 50b Bottom surface, 50c Plug inclined surface, 55 Plug, 56 Plug body, 57 Gas flow path, 57c-57j 1st to 8th gas flow paths, 60 Plug joint section, 60a Raised section, 64a Ring section, 64b Inlet section, 64c Distribution section, 90 Metal bonding material, 92 Through hole, 94 Bonded body, 110 Wafer mounting platform, W Wafer, Z Jig.

Claims

1. A wafer mounting stand comprising: a ceramic plate having a wafer mounting surface on its upper surface and containing electrodes; a plug placement hole extending from the lower surface to the upper surface of the ceramic plate; a plug placed in the plug placement hole and through which gas can pass; and a resin plug joint that joins the upper outer edge of the plug and the upper opening edge of the plug placement hole, and covers the upper outer edge of the plug from above.

2. The wafer mounting stage according to claim 1, wherein the resin contains a filler.

3. The wafer mounting stage according to claim 2, wherein the resin contains 80 to 90% by mass of the filler.

4. The wafer mounting stage according to any one of claims 1 to 3, wherein the upper outer edge of the plug is provided with a plug inclined surface, the upper opening edge of the plug placement hole is provided with a placement hole inclined surface, and the plug joint is provided to fill the groove formed by the plug inclined surface and the placement hole inclined surface.

5. The wafer mounting stage according to claim 4, wherein the angle between the arrangement hole inclined surface and the plug inclined surface is 30 to 60°.

6. The wafer mounting stage according to claim 4, wherein the angle that the arrangement hole inclined surface makes with the horizontal plane is smaller than the angle that the plug inclined surface makes with the horizontal plane.

7. The wafer mounting stage according to claim 4, wherein the arithmetic mean roughness Ra of the arrangement hole inclined surface is greater than the arithmetic mean roughness Ra of the plug inclined surface.

8. A wafer mounting table according to any one of claims 1 to 3, comprising a conductive plate bonded to the lower surface of the ceramic plate and provided with a gas supply passage communicating with the plug placement hole.

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