Wafer placement table

Abstract

This wafer placement base 10 comprises a ceramic plate 20, plug arrangement holes 24, plugs 50, and plug joining parts 60. The ceramic plate 20 has a wafer placement surface 21 on the upper surface thereof and embeds an electrode 22. The plug arrangement holes 24 are formed so as to reach the upper surface from the lower surface of the ceramic plate 20. The plugs 50 are members disposed in the plug arrangement holes 24 and each having an inner section through which a gas can pass. The plug joining parts 60 join the upper surface outer edges of the plugs 50 and the upper opening edges of the plug arrangement holes 24, and are provided so as to cover the upper surface outer edges of the plugs 50 from above.

Description

[Technical field]

[0001] The present invention relates to a wafer stage. [Background technology]

[0002] Conventionally, a wafer mounting table is used in a semiconductor manufacturing apparatus. For example, the wafer mounting table of Patent Document 1 includes a ceramic plate having a wafer mounting surface and a built-in heater, a ventilation path provided in the ceramic plate, and a breathable member arranged in the ventilation path. Examples of the breathable member include a member made of a porous body and a member provided with one or more through holes. As a method for fixing the breathable member to the ventilation path, a method of pressing the breathable member into the ventilation path and a method of bonding the breathable member to the ventilation path using an adhesive are described. In addition, it is described that it is preferable to form a protrusion or the like on the inner wall of the ventilation path to lock the breathable member so that the breathable member does not move due to vacuum suction. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6767829 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the task of forming protrusions or the like on the inner wall of the ventilation path in order to prevent the air-permeable member from moving is not an easy one.

[0005] The present invention has been made to solve the above-mentioned problems, and provides a plug that allows a plug to be removed from a plug placement hole with a simple structure. prevention The main purpose of this project is to [Means for solving the problem]

[0006] [1] The wafer mounting table of the present invention comprises: a ceramic plate having a wafer mounting surface on an 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 allowing gas to pass therethrough; a plug joint portion that joins an outer edge of an upper surface of the plug and an edge of an upper opening of the plug placement hole and is provided so as to cover the outer edge of the upper surface of the plug from above; It is equipped with the following:

[0007] In this wafer mounting table, a plug through which gas can pass is placed in the plug placement hole. The outer edge of the upper surface of the plug and the upper opening edge of the plug placement hole are joined by a plug joint. 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 provided so as to hook onto the upper outer edge of the plug, thereby preventing the plug from slipping upward out of the plug placement hole. In this way, with a simple structure in which the outer edge of the upper surface of the plug is covered from above by the plug joint, it is possible to prevent the plug from slipping upward out of the plug placement hole.

[0008] In this specification, the present invention may be described using terms such as up / down, left / right, front / back, etc., but these terms are merely relative positional relationships. Therefore, when the orientation of the wafer mounting table is changed, up / down may become left / right and left / right may become up / down, but such cases are also included in the technical scope of the present invention.

[0009] [2] In the wafer mounting table of the present invention (the wafer mounting table described in [1] above), the plug bonding portion may be provided around the entire outer edge of the upper surface of the plug. In this way, the plug bonding portion is provided around the entire circumference of the plug, thereby increasing the bonding strength of the plug bonding portion.

[0010] [3] In the wafer mounting table of the present invention (the wafer mounting table described in [1] above), the plug bonding portion may be partially present at two or more locations along the circumferential direction of the outer edge of the upper surface of the plug. In this way, since the plug bonding portion is provided so as to be partially present at two or more locations along the circumferential direction of the outer edge of the upper surface of the plug, rather than along the entire circumference, it is easy to remove the plug bonding portion later. For example, if the need arises for replacing the plug, the plug replacement work becomes easier.

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

[0012] [5] In the wafer mounting table of the present invention (the wafer mounting table according to any one of [1] to [3] above), the plug joint may be a laser welded part formed by laser welding the outer edge of the upper surface of the plug and the edge of the upper opening of the plug arrangement hole. In this way, the plug joint can be formed relatively easily by laser welding. Here, if the plug joint, which is a laser welded part, is provided so as to be partially present at two or more points along the circumferential direction, the number of welded points is reduced, so that the risk of cracks occurring due to laser welding can be reduced. In addition, when it becomes necessary to replace the plug, the work of removing the old plug is facilitated because there are few laser welded parts to be removed. In addition, when a new plug is arranged in the plug arrangement hole after removing the old plug and laser welding is performed, it is sufficient to laser weld the parts other than the parts previously laser welded.

[0013] [6] In the wafer mounting table of the present invention (the wafer mounting table described in [5] above), the laser weld may have an inverted triangular shape when viewed in vertical cross section, with the bottom of the laser weld located on the plug side. In this way, the laser irradiation position in the process of forming the laser weld is on the plug side. Therefore, even if laser irradiation is performed, cracks are unlikely to occur in the ceramic plate. If a crack occurs in the ceramic plate, the plug placement hole and the electrode may become connected by the crack, but this can be prevented.

[0014] [7] The wafer mounting table of the present invention (the wafer mounting table described in any one of [1] to [6] 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 for cooling the ceramic plate, or as a high-frequency electrode for generating plasma above the wafer mounting surface. [Brief description of the drawings]

[0015] [Figure 1] FIG. [Diagram 2] FIG. [Diagram 3] A partially enlarged view of Figure 1. [Figure 4] 5A to 5C are diagrams showing the manufacturing process of the wafer mounting table 10. [Diagram 5] FIG. 2 is an enlarged vertical cross-sectional view of a wafer mounting table 110 having a plug bonding portion 160. [Figure 6] FIG. 2 is a plan view of the periphery of the plug joint 160. [Figure 7] 5A to 5C are diagrams showing a manufacturing process of the wafer mounting table 110. [Figure 8] FIG. 2 is a vertical cross-sectional view of the wafer mounting table 210. [Figure 9] FIG. 2 is an enlarged vertical cross-sectional view of a wafer mounting table having a plug bonding portion 260. [Figure 10] FIG. 4 is an enlarged vertical cross-sectional view of a wafer mounting table having a plug bonding portion 360. [Figure 11]FIG. 4 is a plan view of the periphery of the plug joint 460. [Figure 12] FIG. 4 is a plan view of the periphery of the plug joint 466. [Figure 13] FIG. 13 is an enlarged vertical cross-sectional view of a wafer mounting table having a plug bonding portion 560. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [First embodiment] The first embodiment will be described with reference to the drawings. Fig. 1 is a vertical cross-sectional view of a wafer mounting table 10, Fig. 2 is a plan view of a ceramic plate 20, and Fig. 3 is a partially enlarged view of Fig. 1.

[0017] The wafer mounting table 10 includes a ceramic plate 20, a plug placement hole 24, a base plate (conductive plate) 30, a metal bonding layer 40, a plug 50, and a plug bonding portion 60.

[0018] The ceramic plate 20 is a ceramic disk (e.g., 300 mm in diameter and 5 mm in thickness) made of sintered alumina or sintered aluminum nitride. The upper surface of the ceramic plate 20 is a wafer mounting surface 21. The ceramic plate 20 has an electrode 22 built in. As shown in FIG. 2, a seal band 21a is formed along the outer edge of the wafer mounting surface 21 of the ceramic plate 20, and a plurality of small circular protrusions 21b are formed on the entire surface. The seal band 21a and the small circular protrusions 21b have the same height, which is, for example, several μm to several tens of μm. The electrode 22 is a flat mesh electrode used as an electrostatic electrode, and a DC voltage can be applied to it. When a DC voltage is applied to the electrode 22, the wafer W is attracted and fixed to the wafer mounting surface 21 (specifically, the upper surface of the seal band 21a and the upper surface of the small circular protrusions 21b) by electrostatic attraction force, and when the application of the DC voltage is stopped, the wafer W is released from the attraction and fixation to the wafer mounting surface 21. The portion of the wafer mounting surface 21 on which the seal band 21a and the small circular protrusions 21b are not provided is referred to as a reference surface 21c.

[0019] The plug arrangement hole 24 is a hole extending from the lower surface to the upper surface of the ceramic plate 20, and is a through hole penetrating the ceramic plate 20 in the vertical direction. The plug arrangement hole 24 faces the gas hole 34 of the base plate 30. The plug arrangement hole 24 penetrates the electrode 22 in the vertical direction, but the electrode 22 is not exposed on the inner peripheral surface of the plug arrangement hole 24. The plug arrangement hole 24 is a tapered hole having a truncated cone space in which the area of ​​the upper opening is larger than the area of ​​the lower opening. As shown in FIG. 3, the upper opening edge of the plug arrangement hole 24 is chamfered all around to form an arrangement hole inclined surface 24c. The arrangement hole inclined surface 24c is a flat surface, not a curved surface. As shown in FIG. 2, the plug arrangement hole 24 is provided at a plurality of locations (for example, a plurality of locations provided at equal intervals along the circumferential direction) of the ceramic plate 20.

[0020] The base plate 30 is a conductive disk (a disk having the same diameter as or larger than the ceramic plate 20) with good thermal conductivity. Inside the base plate 30, a coolant flow path 32 in which a coolant (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 part 34a at the top. The large diameter part 34a includes the lower opening of the plug arrangement hole 24 in a plan view. The coolant flow path 32 is formed in a single stroke from the inlet to the outlet over the entire surface of the base plate 30 in a plan view. Examples of materials for the base plate 30 include metals and composite materials. Examples of metals include Mo. Examples of composite materials include composite materials of metals and ceramics. Examples of composite materials of metals and ceramics include metal matrix composite materials (metal matrix composites (MMC)) and ceramic matrix composite materials (ceramic matrix composites (CMC)). Specific examples of such composite materials include materials containing Si, SiC, and Ti, and materials in which a porous SiC body is impregnated with Al and / or Si. The material containing Si, SiC, and Ti is called SiSiCTi, the material in which a porous SiC body is impregnated with Al is called AlSiC, and the material in which a porous SiC body is impregnated with Si is called SiSiC. It is preferable to select a material for the base plate 30 that has a thermal expansion coefficient close to that of the material for the ceramic plate 20. The base plate 30 is also used as an RF electrode. Specifically, an upper electrode (not shown) is disposed above the wafer mounting surface 21, and when high-frequency power is applied between the parallel plate electrodes consisting of the upper electrode and the base plate 30, plasma is generated.

[0021] The metal bonding layer 40 bonds the lower surface of the ceramic plate 20 and the upper surface of the base plate 30. The metal bonding layer 40 is formed, for example, by TCB (thermal compression bonding). TCB refers to a known method in which a metal bonding material is sandwiched between two members to be bonded, and the two members are pressurized and bonded while being heated to a temperature equal to or lower than the solidus temperature of the metal bonding material. The metal bonding layer 40 may be a layer formed of solder or a metal brazing material. The metal bonding layer 40 has a through hole 42. The through hole 42 is provided at a position facing the large diameter portion 34a of the gas hole 34. The through hole 42 is provided coaxially with the large diameter portion 34a, and the diameter of the through hole 42 is the same as the diameter of the large diameter portion 34a. In this specification, "matching" includes not only a case of perfect matching, but also a case of substantial matching (for example, a case within a tolerance range) (the same applies below).

[0022] The plug 50 is disposed in the plug arrangement 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 ceramic porous 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 FIG. 3, the upper outer edge 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 truncated cone-shaped member whose upper surface area is larger than the lower surface area. Therefore, the plug 50 does not come out downward from the plug arrangement hole 24. The upper surface 50a of the plug 50 is exposed to the upper opening of the plug arrangement hole 24 and is flush with the reference surface 21c. In this specification, "same" includes not only completely same, but also substantially same (for example, within the range of tolerance) (the same applies below). The plug 50 and the plug mounting hole 24 are designed in advance so that when the plug 50 is inserted into the plug mounting hole 24 and the outer circumferential surface of the plug 50 is aligned with the inner circumferential surface of the plug mounting hole 24, the height of the upper surface 50a of the plug 50 is aligned with 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 flush with each other. 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 than that.

[0023] The plug joint 60 is provided to join the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24, and to cover the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24 from above. Here, the plug joint 60 is formed by filling a groove formed by the plug inclined surface 50c provided on the entire circumference of the outer edge of the upper surface of the plug 50 and the arrangement hole inclined surface 24c provided on the entire circumference of the upper opening edge of the plug arrangement hole 24 with a ceramic material by a thermal spraying method. The inclined surfaces 24c, 50c are flat surfaces rather than curved surfaces. This groove is ring-shaped in a plan view and has a V-shaped cross section. Both the plug inclined surface 50c and the arrangement hole inclined surface 24c are covered from above by the plug joint 60. The upper surface of the plug joint 60 is flush with the upper surface 50a of the plug 50 and the reference surface 21c of the wafer placement surface 21. However, the height of the upper surface of the plug joint portion 60 may protrude from the reference surface 21c within a range not exceeding the height of the upper surface of the small circular protrusion 21b, or may be slightly recessed below the reference surface 21c.

[0024] Next, an example of use of the wafer mounting table 10 thus configured will be described. First, the wafer W is mounted on the wafer mounting surface 21 with the wafer mounting table 10 installed in a chamber (not shown). Then, the chamber is depressurized by a vacuum pump to adjust the chamber to a predetermined vacuum level, and a DC voltage is applied to the electrode 22 of the ceramic plate 20 to generate an electrostatic adsorption force, so that the wafer W is adsorbed and fixed to the wafer mounting surface 21 (specifically, the upper surface of the seal band 21a or the upper surface of the circular small protrusion 21b). Next, the chamber is set to a reactive 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 table 10 to generate plasma. The surface of the wafer W is treated by the generated plasma. A coolant is circulated through the coolant flow passage 32 of the base plate 30. A backside gas is introduced into the gas hole 34 from a gas cylinder (not shown). A thermally conductive gas (for example, helium, etc.) is used as the backside gas. The backside gas is supplied and sealed in the space between the back surface of the wafer W and the reference surface 21c of the wafer mounting surface 21 through the gas holes 34, the through holes 42, and the plug 50. The presence of this backside gas allows efficient thermal conduction between the wafer W and the ceramic plate 20.

[0025] Next, a manufacturing example of the wafer mounting table 10 will be described with reference to FIG. 4. FIG. 4 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 (FIG. 4A). The ceramic plate 20 incorporates an electrode 22 and has a plug mounting hole 24. The upper opening edge of the plug mounting hole 24 is chamfered to form a mounting hole inclined surface 24c. The base plate 30 has a coolant 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 has a through hole 92 at a position facing the large diameter portion 34a of the gas hole 34.

[0026] Next, the 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 ceramic plate 20 is laminated so that the plug arrangement hole 24, the through hole 92 of the metal bonding material 90, and the gas hole 34 of the base plate 30 are coaxial. Then, the laminate is pressed and bonded at a temperature equal to or lower than the solidus temperature of the metal bonding material 90 (for example, a temperature equal to or higher than the solidus temperature minus 20°C and equal to or lower than the solidus temperature), and then returned to room temperature (TCB). As a result, the metal bonding material 90 and the through hole 92 become the metal bonding layer 40 and the through hole 42, respectively, and a bonded body 94 in which the ceramic plate 20 and the base plate 30 are bonded by the metal bonding layer 40 is obtained (FIG. 4B). Note that an Al-Mg-based bonding material or an Al-Si-Mg-based bonding material can be used as the metal bonding material 90. It is preferable to use a metal bonding material 90 having a thickness of about 100 μm.

[0027] Next, a truncated cone-shaped plug 50 is prepared (FIG. 4B). The upper outer edge of the plug 50 is chamfered to form a plug inclined surface 50c. Next, the plug 50 is inserted into the plug mounting hole 24 (FIG. 4C). Then, the plug inclined surface 50c of the plug 50 and the mounting hole inclined surface 24c of the plug mounting hole 24 form a groove 70 that is ring-shaped in plan view and has a V-shaped cross section.

[0028] Next, the groove 70 is filled with a ceramic material by a thermal spraying method. As a result, the groove 70 is filled with the plug joint 60. The plug inclined surface 50c and the arrangement hole inclined surface 24c are covered from above by the plug joint 60. The raised portion of the plug joint 60 is made flat by grinding. Finally, the wafer mounting table 10 is obtained by providing the seal band 21a and the small circular protrusions 21b on the upper surface of the ceramic plate 20 (FIG. 4D). Note that the plug joint 60 may be formed by a thermal spraying method after providing the seal band 21a and the small circular protrusions 21b on the upper surface of the ceramic plate 20.

[0029] In the wafer mounting table 10 described above in detail, the plug 50, through which gas can pass, is placed in the plug placement hole 24. The outer edge of the upper surface 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 outer edge of the upper surface of the plug 50 from above, thereby preventing the plug 50 from slipping out upward from the plug placement hole 24. In this way, with the simple structure of covering the outer edge of the upper surface of the plug 50 from above with the plug joint 60, it is possible to prevent the plug 50 from slipping out upward from the plug placement hole 24.

[0030] In addition, since the plug joint 60 is provided over the entire circumference of the plug 50, the joint strength of the plug joint 60 is increased.

[0031] Furthermore, the plug joint 60 is a sprayed portion provided so as to fill the groove 70 formed by the plug inclined surface 50c and the arrangement hole inclined surface 24c. Therefore, the plug joint 60 can be formed relatively easily by spraying.

[0032] [Second embodiment] The wafer mounting table 110 of the second embodiment will be described with reference to the drawings. Fig. 5 is an enlarged vertical cross-sectional view of the wafer mounting table 110 having a plug bonding portion 160, and Fig. 6 is an enlarged vertical cross-sectional view of the wafer mounting table 110 having a plug bonding portion 160. joint 5 to 7, the same components of the wafer mounting table 110 as those of the wafer mounting table 10 are denoted by the same reference numerals and will not be described.

[0033] The wafer mounting table 110 includes a ceramic plate 20 , a plug placement hole 24 , a base plate (conductive plate) 30 , a metal bonding layer 40 , a plug 50 , and a plug bonding portion 160 .

[0034] The plug joint 160 is a laser welded portion formed by laser welding the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24. The plug joint 160 has an inverted triangular shape when viewed in vertical cross section, with the bottom of the plug joint 160 located at the boundary between the plug 50 and the plug arrangement hole 24. This plug joint 160 joins the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24, and is provided so as to cover the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24 from above. The plug joint 160 is provided around the entire circumference of the outer edge of the upper surface of the plug 50.

[0035] The use of the wafer stage 110 is similar to that of the wafer stage 10, and therefore the description thereof will be omitted.

[0036] Among the manufacturing examples of the wafer mounting table 110, differences from the manufacturing example of the wafer mounting table 10 will be described. When manufacturing the wafer mounting table 10, the upper opening edge of the plug arrangement hole 24 is C-chamfered to form the arrangement hole inclined surface 24c, and the upper surface outer edge of the plug 50 is C-chamfered to form the plug inclined surface 50c. However, when manufacturing the wafer mounting table 110, such chamfering is not performed. Therefore, when the plug 50 is inserted into the plug arrangement hole 24, the upper opening edge of the plug arrangement hole 24 and the upper surface outer edge of the plug 50 come into contact with each other (FIG. 7A). In this state, a laser (e.g., a nanosecond laser, a picosecond laser, a femtosecond laser, etc.) is irradiated to the boundary between the upper opening edge of the plug arrangement hole 24 and the upper surface outer edge of the plug 50 to locally raise the temperature. As a result, the upper opening edge of the plug arrangement hole 24 and the upper surface outer edge of the plug 50 are welded to form a laser welded portion. Due to the nature of laser welding, the cross section of the laser weld becomes smaller in width (diameter) from top to bottom. The raised portion of the laser weld is ground flat, forming a plug joint 160 (FIG. 7B).

[0037] In the wafer mounting table 110 described above, the plug bonding portion 160 is provided so as to cover the outer edge of the upper surface of the plug 50 from above. The plug bonding portion 160 is provided so as to hook onto the upper outer edge of the plug 50, thereby preventing the plug 50 from slipping out upward from the plug placement hole 24. In this way, with the simple structure in which the outer edge of the upper surface of the plug 50 is covered from above with the plug bonding portion 160, it is possible to prevent the plug 50 from slipping out upward from the plug placement hole 24.

[0038] In addition, since the plug joint 160 is provided around the entire outer edge of the upper surface of the plug 50, the joint strength of the plug joint 160 is increased.

[0039] Furthermore, the plug joint 160 is a laser welded portion obtained by laser welding the boundary between the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24. Therefore, the plug joint 160 can be formed relatively easily by laser welding. When the plug joint 160 is formed by laser welding, there is no need to chamfer the outer edge of the upper surface of the plug 50 or the upper opening edge of the plug arrangement hole 24 as in the first embodiment.

[0040] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms within the technical scope of the present invention.

[0041] In the above-described first and second embodiments, the plug 50 made of a porous body is exemplified as a plug that allows gas to flow in the vertical direction, but the plug is not particularly limited to this. For example, as such a plug, a dense plug having a flow path (for example, a straight flow path or a spiral flow path) that allows gas to flow in the vertical direction may be used.

[0042] In the above-described first and second embodiments, the plug 50 has a truncated cone shape, but the present invention is not limited to this. For example, a cylindrical plug may be used.

[0043] In the first and second embodiments described above, a stepped hole having a large diameter portion 34a above the gas hole 34 is used, but the present invention is not limited to this. For example, a straight hole may be used as the gas hole 34.

[0044] In the above-described first and second embodiments, an electrostatic electrode has been exemplified as the electrode 22 built into the ceramic plate 20, but the present invention is not limited thereto. For example, instead of or in addition to the electrode 22, a heater electrode (resistance heating element) or an RF electrode may be built into the ceramic plate 20.

[0045] In the above-described first and second embodiments, the ceramic plate 20 and the base plate 30 are joined by the metal joining layer 40. However, instead of the metal joining layer 40, a resin adhesive layer may be used.

[0046] In the first embodiment described above, the base plate 30 is provided with a gas supply aisle However, the present invention is not limited to this. For example, as shown in FIG. 8, the base plate 30 may be provided with a ring portion 64a concentric with the base plate 30 in a plan view, an inlet portion 64b for introducing gas from the back surface of the base plate 30 to the ring portion 64a, and a distributor portion 64c for distributing gas from the ring portion 64a to each plug 50. In FIG. 8, the same components as those in the first embodiment are given the same reference numerals. The number of the inlet portions 64b may be less than the number of the distributor portions 64c, for example, one. In this way, the number of external gas pipes connected to the lower surface of the base plate 30 can be less than the number of the plugs 50. Such a configuration may be adopted in the second embodiment.

[0047] In the first embodiment described above, the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24 are chamfered with C-shape, but this is not limited to C-shape. For example, R-shape may be applied. In that case, each inclined surface 24c, 50c becomes a curved surface (convex surface). In addition, in the state before the plug joint portion 60 is formed (FIG. 4C), the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24 form a groove 70 having a V-shaped cross section, but this is not particularly limited. For example, the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24 may be processed so that the outer edge of the upper surface of the plug 50 and the upper opening edge of the plug arrangement hole 24 form a groove having a U-shaped cross section. In that case, the cross section of the plug joint portion 60 becomes approximately rectangular.

[0048] In the first embodiment described above, the upper opening edge of the plug arrangement hole 24 is chamfered all around to form the arrangement hole inclined surface 24c, but the arrangement hole inclined surface 24c may not be formed. An example of such a case is shown in Fig. 9. In Fig. 9, the same components as in the first embodiment are given the same reference numerals. The plug joint portion 260 in Fig. 9 has a plug inclined surface 50c provided on the outer edge of the upper surface of the plug 50 and an arrangement hole inclined surface 50c. 24c The plug joint portion 260 is a sprayed portion that joins the upper opening edge of the plug arrangement hole 24, which does not have a plug 50 disposed therein. The plug joint portion 260 is also formed by spraying so as to cover the upper outer edge of the plug inclined surface 50c from above. Even in this manner, the plug 50 can be prevented from slipping out upward from the plug arrangement hole 24 with a simple structure.

[0049] In the first embodiment described above, the plug inclined surface 50c is formed by chamfering the entire circumference of the outer edge of the upper surface of the plug 50, but the plug inclined surface 50c may not be formed. An example of such a case is shown in FIG. 10. In FIG. 10, the same components as those in the first embodiment are given the same reference numerals. The plug joint portion 360 in FIG. 10 is a sprayed portion that joins the outer edge of the upper surface of the plug 50 that does not have the plug inclined surface 50c and the arrangement hole inclined surface 24c provided on the upper opening edge of the plug arrangement hole 24. The plug joint portion 360 is also formed by spraying so as to cover the outer edge of the upper surface of the plug 50 and the arrangement hole inclined surface 24c of the plug arrangement hole 24 from above. Even in this way, the plug 50 can be prevented from coming out of the plug arrangement hole 24 upward with a simple structure.

[0050] In the first embodiment described above, the plug joint 60 is formed by thermal spraying, but the method is not limited to thermal spraying. For example, the plug joint 60 may be formed by aerosol deposition. Alternatively, the plug joint 60 may be formed by filling a groove 70 having a V-shaped cross section as shown in FIG. 4C with ceramic powder, and then locally heating the ceramic powder with a laser or the like to sinter the ceramic powder.

[0051] In the second embodiment described above, the plug joint 160 is provided around the entire circumference of the outer edge of the upper surface of the plug 50, but the present invention is not limited thereto. For example, as shown in FIG. 11, the plug joint 460 may be provided so as to be partially present at two or more locations (here, eight locations) along the circumferential direction of the outer edge of the upper surface of the plug 50. In FIG. 11, the same configuration as in the second embodiment is given the same reference numerals. In this way, although the joint strength is lower than that of the second embodiment, a strength that is not problematic at a practical level can be obtained. In addition, since there are fewer locations to be irradiated with the laser compared to the second embodiment, cracks are less likely to occur in the plug 50 and the ceramic plate 20. Furthermore, when it becomes necessary to replace the plug 50, since the length of the plug joint 460 is shorter than that of the second embodiment, it is easier to remove the plug joint 460. When a new plug 50 is placed in the plug arrangement hole 24 after removing the old plug 50 and laser welding it, as shown in FIG. 12, a location 464 different from the previously laser-welded location 462 (shaded) is laser-welded to form a new plug joint 466. This is because previously laser welded portion 462 cannot be laser welded again. If it is desired to change the plug two or more times, it is sufficient to leave portions that can be laser welded according to the number of times.

[0052] The plug joint 60 of the first embodiment described above may be provided partially at two or more locations, similar to the plug joint 460 of FIG. 11. In this way, although the joint strength is lower than that of the first embodiment, a strength that is acceptable at a practical level can be obtained. In addition, since there are fewer locations to be sprayed compared to the first embodiment, cracks are less likely to occur in the plug 50 and the ceramic plate 20, and since the length of the sprayed portion is short, it is easy to remove the sprayed portion when the plug 50 needs to be replaced. However, in the case of spraying, it is possible to spray again even at locations that have been sprayed in the past. Therefore, even if the plug joint 60 is provided around the entire circumference of the outer edge of the upper surface of the plug 50 as in the first embodiment, it is possible to spray again around the entire circumference of the outer edge of the upper surface of the replaced plug 50 and the upper opening edge of the plug arrangement hole 24.

[0053] In the above-described second embodiment, the bottom 160a of the plug joint 160, which is a laser welded portion and has an inverted triangular cross section, is located at the boundary between the plug 50 and the plug arrangement hole 24, but is not particularly limited to this. For example, as in the plug joint 560 shown in FIG. 13, the bottom 560a of the plug joint 560 may be located on the plug 50 side. In FIG. 13, the same reference numerals are used for the same configuration as in the second embodiment. In this case, the laser irradiation position in the process of forming the plug joint 560 is on the plug side. Therefore, even if the laser irradiation is performed, cracks are unlikely to occur in the ceramic plate 20. If a crack occurs in the ceramic plate 20, the plug arrangement hole 24 and the electrode 22 may communicate with each other due to the crack, which is likely to cause a malfunction, but by adopting the configuration of FIG. 13, such malfunctions can be prevented.

[0054] In the first and second embodiments described above, the outer circumferential surface of the plug 50 may be brought into close contact with the inner circumferential surface of the plug mounting hole 24. This has the effect of suppressing discharge between the outer circumferential surface of the plug 50 and the inner circumferential surface of the plug mounting hole 24 when plasma is generated. [Industrial Applicability]

[0055] The present invention can be used for wafer mounting tables used in semiconductor manufacturing equipment, such as ceramic heaters, electrostatic chuck heaters, and electrostatic chucks. [Explanation of symbols]

[0056] 10 wafer mounting table, 20 ceramic plate, 21 wafer mounting surface, 21a seal band, 21b circular small protrusion, 21c reference surface, 22 electrode, 24 plug arrangement hole, 24c arrangement hole inclined surface, 30 base plate, 32 coolant flow path, 34 gas hole, 34a large diameter portion, 40 metal bonding layer, 42 through hole, 50 plug, 50a upper surface, 50b lower surface, 50c plug inclined surface, 64a ring portion, 64b introduction portion, 64c distribution portion, 90 metal bonding material, 92 through hole, 94 bonding body, 110, 210 wafer mounting table, 60, 160, 260, 360, 460, 466, 560 plug joint portion, 160a, 560a bottom, W wafer.

Claims

1. a ceramic plate having a wafer mounting surface on an 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 allowing gas to pass therethrough; a plug joint portion that joins an outer edge of an upper surface of the plug and an edge of an upper opening of the plug placement hole and is provided so as to cover the outer edge of the upper surface of the plug from above; Equipped with The plug arrangement hole is a tapered hole having a truncated cone space in which the area of ​​an upper opening is larger than the area of ​​a lower opening, The plug is a truncated cone-shaped member having an upper surface area larger than a lower surface area. Wafer placement stage.

2. The plug joint portion is provided around the entire periphery of the upper surface of the plug. The wafer stage according to claim 1 .

3. the plug joint portion is present at two or more locations along the circumferential direction of the outer edge of the upper surface of the plug; The wafer stage according to claim 1 .

4. The plug has an inclined plug surface on an outer edge of an upper surface thereof, The plug arrangement hole has an inclined surface on an upper opening edge thereof, The plug joint portion is a sprayed portion provided so as to fill a groove formed by the plug inclined surface and the arrangement hole inclined surface. The wafer mounting table according to any one of claims 1 to 3.

5. The plug joint portion is a laser welded portion formed by laser welding an upper surface outer edge of the plug and an upper opening edge of the plug placement hole. The wafer mounting table according to any one of claims 1 to 3.

6. The laser weld has a shape of an inverted triangle when viewed in vertical cross section, and the bottom of the laser weld is located on the plug side. The wafer stage according to claim 5 .

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

8. The plug joint is a member separate from the ceramic plate. The wafer mounting table according to any one of claims 1 to 3.

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