Member for semiconductor manufacturing apparatus

Abstract

A wafer mounting table 10, which is one example of a member for a semiconductor manufacturing apparatus, comprises: a ceramic plate 20 that has, on the upper surface thereof, at least one of a wafer mounting surface 21 and a focus ring mounting surface 26; a plug placement hole 24 that penetrates the ceramic plate 20 in the vertical direction and has a tapered inner peripheral surface 24a tapering toward the lower side thereof; and a plug 50 that is fitted into the plug placement hole 24, has a tapered outer peripheral surface 50a tapering toward the lower side thereof, and allows gas to flow in the vertical direction. The outer peripheral surface 50a of the plug 50 has a gentler slope than the inner peripheral surface 24a of the plug placement hole 24.

Description

Semiconductor manufacturing equipment components

[0001] The present invention relates to a member for a semiconductor manufacturing device.

[0002] Conventionally, semiconductor manufacturing equipment components have been used, each of which includes a ceramic plate having a wafer-mounting surface on its upper surface. For example, a semiconductor manufacturing equipment component disclosed in Patent Document 1 includes a plug placement hole that vertically penetrates the ceramic plate, and a plug that is placed in the plug placement hole and allows gas to flow vertically. The plug has, for example, an inverted truncated cone shape with an upper base larger than a lower base, and is placed in a plug placement hole of a shape that matches the plug placement hole.

[0003] WO 2023 / 153021 Pamphlet (Figure 13 and paragraph 0041)

[0004] In the semiconductor manufacturing equipment component described above, the plug is bonded to the plug mounting hole with an adhesive. However, the inventors have considered press-fitting the plug into the plug mounting hole. In this case, a relatively high press-fit load is sometimes required to press-fit the plug to the desired depth. However, increasing the press-fit load results in an excessively high fitting strength, which can make it impossible to remove the plug when performing rework to replace it with a new plug.

[0005] The present invention has been made to solve these problems, and a main object of the present invention is to make it possible to easily remove a plug even when the plug is press-fitted with a relatively high press-fitting load.

[0006] [1] A semiconductor manufacturing equipment member of the present invention comprises: a ceramic plate having at least one of a wafer mounting surface and a focus ring mounting surface on its upper surface; a plug placement hole that vertically penetrates the ceramic plate and has a tapered inner circumferential surface that tapers downward; and a plug that is fitted into the plug placement hole and has a tapered outer circumferential surface that tapers downward, allowing gas to flow in the vertical direction, wherein the outer circumferential surface of the plug is more gently inclined than the inner circumferential surface of the plug placement hole.

[0007] In this semiconductor manufacturing equipment component, a plug having a tapered outer peripheral surface tapering downward is fitted into a plug placement hole having a tapered inner peripheral surface tapering downward, and the outer peripheral surface of the plug is more gently inclined than the inner peripheral surface of the plug placement hole. Therefore, even if the plug is press-fitted with a relatively high press-fit load, it can be easily removed. The reason for this effect is presumed to be as follows: That is, because the outer peripheral surface of the plug is more gently inclined than the inner peripheral surface of the plug placement hole, it is thought that the plug is mainly fitted into the large-diameter upper portion of the plug placement hole. Because the ceramic plate is thick and less likely to deform in this portion, it is presumed that the fitting strength for the plug is not too high, even if the plug is press-fitted with a relatively high press-fit load, and therefore the plug can be easily removed.

[0008] Although the present invention is sometimes described using terms such as up / down, left / right, front / back, etc., these terms merely refer to relative positional relationships. Therefore, when the orientation of a semiconductor manufacturing equipment component is changed, up / down may become left / right, or left / right may become up / down, and such cases are also within the technical scope of the present invention.

[0009] [2] In the semiconductor manufacturing equipment component described above (the semiconductor manufacturing equipment component described in [1] above), the difference obtained by subtracting the inclination angle α of the outer peripheral surface of the plug from the inclination angle θ of the inner peripheral surface of the plug placement hole may be 0.2° or less. If this difference is 0.2° or less, the gap between the outer peripheral surface of the plug and the inner peripheral surface of the plug placement hole can be reduced. Note that, in this specification, the inclination angle α of the outer peripheral surface of the plug is defined as the angle between a plane perpendicular to the axis of the plug and the outer peripheral surface of the plug (where 0°<α<90°). Furthermore, the inclination angle θ of the inner peripheral surface of the plug placement hole is defined as the angle between a plane perpendicular to the axis of the plug placement hole and the inner peripheral surface of the plug placement hole (where 0°<θ<90°).

[0010] [3] In the semiconductor manufacturing equipment component described above (the semiconductor manufacturing equipment component described in [1] or [2] above), the difference obtained by subtracting the inclination angle α of the outer peripheral surface of the plug from the inclination angle θ of the inner peripheral surface of the plug placement hole may be 0.05° or more and 0.10° or less. If this difference is 0.05° or more, the plug can be more easily removed. Furthermore, if this difference is 0.10° or less, the gap between the plug and the ceramic plate can be made smaller.

[0011] [4] In the semiconductor manufacturing equipment member described above (the semiconductor manufacturing equipment member described in any one of [1] to [3] above), the inclination angle θ of the inner circumferential surface of the plug placement hole may be equal to or greater than 70° and less than 88°.

[0012] [5] In the semiconductor manufacturing equipment member described above (the semiconductor manufacturing equipment member described in any one of [1] to [4] above), the pull-out strength required to pull the plug out toward the wafer-mounting surface may be 100 N or less. The smaller the pull-out strength, the easier it is to remove the plug.

[0013] [6] The semiconductor manufacturing equipment member described above (the semiconductor manufacturing equipment member described in any one of [1] to [5]) may further include a conductive base material bonded to the underside of the ceramic plate and provided with a gas supply path communicating with the plug placement hole. The conductive base material may be used, for example, as a cooling plate for cooling the ceramic plate, or as a radio frequency electrode (RF electrode) for generating plasma above the wafer mounting surface.

[0014] [7] In the semiconductor manufacturing equipment member described above (the semiconductor manufacturing equipment member described in any one of [1] to [6] above), the ceramic plate may have an electrode built in. The electrode may be, for example, an electrostatic electrode, a heater electrode (resistive heating element), or an RF electrode.

[0015] 1 is a longitudinal sectional view of a wafer mounting table 10, which is an example of a semiconductor manufacturing equipment member of the present invention. FIG. 2 is a plan view of a ceramic plate 20. FIG. 3 is a partial enlarged view of FIG. 1. FIG. 4 is a manufacturing process diagram for the wafer mounting table 10. FIG. 5 is an explanatory diagram showing an example of a method for measuring punching strength. FIG. 6 is a partial enlarged view of the wafer mounting table 110. FIG. 7 is a partial enlarged view of the wafer mounting table 210. FIG. 8 is an explanatory diagram of a plug 350. FIG. 9 is an explanatory diagram of a plug 450. FIG. 10 is a longitudinal sectional view of the wafer mounting table 510. FIG. 11 is an explanatory diagram showing the relationship between press-fit strength and punching strength.

[0016] A preferred embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a vertical cross-sectional view of a wafer stage 10, which is an example of a semiconductor manufacturing equipment member of the present invention. Fig. 2 is a plan view of a ceramic plate 20. Fig. 3 is an enlarged view of a portion of Fig. 1.

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

[0018] The ceramic plate 20 is a circular plate (e.g., 300 mm in diameter) made of ceramic, such as sintered alumina or sintered aluminum nitride. The ceramic plate 20 is preferably dense. The dense material has a porosity of 5% or less (preferably 3% or less, more preferably 1% or less). The porosity of the ceramic plate 20 is the open porosity measured in accordance with JIS R1634:1998. The thickness of the ceramic plate 20 is, for example, 1 mm or more and 5 mm or less. The ceramic plate 20 has, on its upper surface, a wafer mounting surface 21 and a focus ring (FR) mounting surface 26. The wafer mounting surface 21 is a circular surface on which a wafer W is mounted. As shown in FIG. 2 , the wafer mounting surface 21 has a seal band 21a formed along its outer edge and a plurality of small circular protrusions 21b formed all over its surface. The seal band 21a and the small circular protrusions 21b have the same height, e.g., several μm to several tens of μm. The portion of the wafer mounting surface 21 that is not provided with the seal band 21a or the small circular protrusions 21b is referred to as the reference surface 21c. The FR mounting surface 26 is an annular surface provided around the wafer mounting surface 21. The height of the FR mounting surface 26 is one step lower than the height of the wafer mounting surface 21. An annular focus ring 60 is mounted on the FR mounting surface 26. The focus ring 60 is made of, for example, silicon. A circumferential groove 62 is formed on the upper inner surface of the focus ring 60 to prevent contact with the wafer W. The outer diameter of the focus ring 60 is larger than the outer diameter of the ceramic plate 20. Therefore, the focus ring 60 is mounted on the FR mounting surface 26 in an overhanging state outside the wafer mounting table 10. The ceramic plate 20 incorporates an electrode 22. The electrode 22 is a planar mesh electrode used as an electrostatic electrode, to which a DC voltage can be applied. When a DC voltage is applied to this electrode 22, the wafer W is attracted and fixed to the wafer mounting surface 21 (specifically, the upper surface of the seal band 21 a and the upper surface of the small circular protrusion 21 b) by electrostatic attraction, and when the application of the DC voltage is released, the wafer W is released from the attracting and fixing position to the wafer mounting surface 21.

[0019] The plug arrangement hole 24 is a hole that penetrates the ceramic plate 20 in the vertical direction. In this example, it is a through-hole that extends from the lower surface of the ceramic plate 20 to the wafer mounting surface 21. 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 at the inner circumferential surface of the plug arrangement hole 24. The plug arrangement hole 24 is a tapered hole having a truncated cone space with an upper opening area larger than a lower opening area, and has a tapered inner circumferential surface 24a that tapers downward. The inclination angle θ (see FIG. 3 ) of the inner circumferential surface 24a of the plug arrangement hole 24 is, for example, 70° or more and less than 88°, preferably 75° or more and 87° or less. As shown in FIG. 2 , the plug arrangement holes 24 are provided at multiple locations (e.g., multiple locations equally spaced along the circumferential direction) so as to open to the wafer mounting surface 21 of the ceramic plate 20. The diameters of the upper and lower openings of the plug placement hole 24 are both, for example, 1 mm or more and 5 mm or less.

[0020] The base plate 30 is a conductive disk (having the same diameter as or larger than the ceramic plate 20) with good thermal conductivity. The base plate 30 includes a coolant flow path 32 through which a coolant (e.g., an electrically insulating liquid such as a fluorine-based inert liquid) circulates, and a gas hole 34 through which gas is supplied to the plug 50. The gas hole 34 is disposed to vertically penetrate the base plate 30 and has a large-diameter portion 34a at its upper end. The large-diameter portion 34a encompasses the lower opening of the plug placement hole 24 in a plan view. The coolant flow path 32 is formed in a single stroke from the inlet to the outlet across 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 molybdenum (Mo). Examples of composite materials include a composite material of metal and ceramic. Examples of composite materials of metal and ceramic 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 porous SiC is impregnated with Al and / or Si. A material containing Si, SiC, and Ti is called SiSiCTi, a material in which porous SiC is impregnated with Al is called AlSiC, and a material in which porous SiC 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 also serves as an RF electrode. Specifically, an upper electrode (not shown) is disposed above the wafer mounting surface 21, and plasma is generated when high-frequency power is applied between the parallel plate electrodes consisting of the upper electrode and the base plate 30.

[0021] The metal bonding layer 40 bonds 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 thermal compression bonding (TCB). TCB is a known method in which a metal bonding material is sandwiched between two components to be bonded and the two components are pressure-bonded while heated to a temperature below the solidus temperature of the metal bonding material. The metal bonding layer 40 may be a layer formed of solder or a brazing metal. The metal bonding layer 40 has a through hole 42. The through hole 42 is located opposite the large-diameter portion 34a of the gas hole 34. The through hole 42 is coaxial 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, the term "coaxial" includes not only completely coaxial but also substantially coaxial (e.g., within a tolerance range) (the same applies hereinafter). In addition, in this specification, "match" includes not only a perfect match but also a substantial match (for example, within a tolerance range) (the same applies hereinafter).

[0022] The plug 50 is positioned and fitted into the plug placement hole 24 so as to be coaxial with the plug placement hole 24. The plug 50 is an electrically insulating member that allows gas to flow vertically. Here, the plug 50 is a ceramic member such as alumina or aluminum nitride, and is formed, for example, from the same material as the ceramic plate 20. The plug 50 has a dense portion 52 and a porous vent portion 54 that vertically penetrates the dense portion 52. The dense portion has a porosity of 5% or less (preferably 3% or less, more preferably 1% or less). The porosity of the dense portion of the plug 50 is determined as follows: SEM (scanning electron microscope) observation is performed at 3000x magnification, and the brightness distribution of the obtained SEM image is binarized into a solid portion and a pore portion using Otsu's binarization. The area ratio of the pore portion to the entire surface is calculated as the porosity. The vent portion 54 is formed, for example, from a porous body made of the same material as the dense portion 52. The porous portion has a porosity of more than 5% but less than 100%. The porosity of the vent portion 54 is preferably 30% or more, and the average pore diameter is preferably 20 μm or more. The porosity and pore diameter of the porous portion of the plug 50 are measured by mercury intrusion porosimetry (JIS R1655:2003). The plug 50 is a truncated cone-shaped member with an upper surface 56 (see FIG. 3) larger than the area of ​​the lower surface 58 (see FIG. 3), and has a tapered outer peripheral surface 50a that tapers downward. The outer peripheral surface 50a of the plug 50 is more gently inclined than the inner peripheral surface 24a of the plug placement hole 24. In other words, the inclination angle α (see FIG. 3) of the outer peripheral surface 50a of the plug 50 is smaller than the inclination angle θ of the inner peripheral surface 24a of the plug placement hole 24. The difference (θ-α) obtained by subtracting the inclination angle α of the outer peripheral surface 50a of the plug 50 from the inclination angle θ of the inner peripheral surface 24a of the plug positioning hole 24 may be, for example, 0.2° or less, or 0.03° to 0.15°, or 0.05° to 0.10°. The upper surface 56 of the plug 50 is exposed to the upper opening of the plug positioning hole 24 and is disposed flush with the reference surface 21c. In this specification, the term "same" includes not only completely identical but also substantially identical (for example, within a tolerance range) (the same applies hereinafter).The plug 50 and the plug positioning hole 24 are designed in advance so that when the plug 50 is inserted into the plug positioning hole 24 and press-fitted with a predetermined press-fit strength, the height of the upper surface 56 of the plug 50 coincides with the height of the reference surface 21c of the ceramic plate 20. Therefore, the upper surface 56 of the plug 50 and the reference surface 21c of the ceramic plate 20 can be easily arranged on the same plane. The height of the lower surface 58 of the plug 50 may be the same as, higher than, or lower than the height of the lower surface of the ceramic plate 20.

[0023] Next, an example of how the wafer mounting table 10 configured as described above is described. First, the wafer mounting table 10 is installed in a chamber (not shown), and a wafer W is placed on the wafer mounting surface 21. The chamber is then depressurized using a vacuum pump to a predetermined vacuum level, and a DC voltage is applied to the electrode 22 of the ceramic plate 20 to generate an electrostatic attraction force, thereby attracting and fixing the wafer W to the wafer mounting surface 21 (specifically, the upper surface of the seal band 21a or the upper surface of the small circular protrusions 21b). Next, a reactive gas atmosphere at a predetermined pressure (e.g., several tens to several hundreds of Pa) is created in the chamber. In this state, a high-frequency voltage is applied between an upper electrode (not shown) installed in 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 with the generated plasma. A coolant circulates through the coolant flow path 32 in the base plate 30. A backside gas is introduced through the gas hole 34 from a gas cylinder (not shown). A thermally conductive gas (e.g., helium) is used as the backside gas. The backside gas is supplied and sealed in the space between the backside 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 plugs 50. The presence of this backside gas ensures efficient heat conduction between the wafer W and the ceramic plate 20. Furthermore, the presence of the electrically insulating plugs 50 arranged in the plug arrangement holes 24 increases the creepage distance between the wafer W and the base plate 30, thereby suppressing discharge within the plug arrangement holes 24.

[0024] 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 for 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 includes a plug placement hole 24. The plug placement hole 24 has a tapered inner circumferential surface 24a that tapers downward. The inclination angle θ of the inner circumferential surface 24a of the plug placement hole 24 is, for example, 70° or greater and less than 88°. The base plate 30 includes a coolant flow path 32 and a gas hole 34. The gas hole 34 has a large-diameter portion 34a at its upper portion. The metal bonding material 90 includes a through-hole 92 at a position facing the large-diameter portion 34a of the gas hole 34.

[0025] Next, a metal bonding material 90 is sandwiched between the underside of the ceramic plate 20 and the top side of the base plate 30 to form a laminate. The ceramic plate 20 is stacked so that the plug placement hole 24, the through-hole 92 in the metal bonding material 90, and the gas hole 34 in 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 (e.g., a temperature 20°C below the solidus temperature but below the solidus temperature), and then returned to room temperature (TCB). This results in the metal bonding material 90 and the through-hole 92 becoming the metal bonding layer 40 and the through-hole 42, respectively, resulting in a bonded assembly 94 in which the ceramic plate 20 and the base plate 30 are bonded by the metal bonding layer 40 ( FIG. 4B ). The metal bonding material 90 can be an Al-Mg-based bonding material or an Al-Si-Mg-based bonding material. It is preferable to use a metal bonding material 90 with a thickness of approximately 100 μm.

[0026] Next, a truncated cone-shaped plug 50 is prepared ( FIG. 4B ). The plug 50 has a dense portion 52 and a porous vent portion 54 that vertically penetrates the dense portion 52. The plug 50 has a tapered outer peripheral surface 50a, with the inclination angle α of the outer peripheral surface 50a of the plug 50 being smaller than the inclination angle θ of the inner peripheral surface 24a of the plug placement hole 24. The outer diameter of the plug 50 in a predetermined range on the upper end side (e.g., at least within a range of 0.2 mm from the upper end) is slightly larger (e.g., by 20 μm or less) than the inner diameter at a corresponding position in the plug placement hole 24 (a position at the same height when the plug 50 is fitted into the plug placement hole 24). The height of the plug 50 is, for example, the same as the height of the plug placement hole 24 (i.e., the height of the ceramic plate 20). Next, the plug 50 is press-fitted into the plug arrangement hole 24 with a predetermined press-fit strength (the load applied to the plug 50 during press-fitting) ( FIG. 4C ). The press-fit strength is, for example, 100 N or more and 700 N or less. The press-fitting deforms the ceramic plate 20, particularly the upper portion thereof, around the inner circumferential surface 24a of the plug arrangement hole 24, and the plug 50, particularly the upper portion thereof, around the outer circumferential surface 50a thereof. This deformation of the ceramic plate 20 and the plug 50 allows the plug 50 to fit into the plug arrangement hole 24. While the plug 50 and the plug arrangement hole 24 are deformed by the press-fitting, it is sufficient that the inclination angle θ is greater than the inclination angle α at least before the press-fitting. Because the deformation due to the press-fitting is considered small in the lower portions of the plug 50 and the ceramic plate 20, the inclination angle α, the inclination angle θ, and the angle difference θ-α may be determined in the press-fitted state. At this time, for example, the inclination angle α, the inclination angle θ, and the angle difference θ-α may be obtained by using X-ray CT to check the lower gap between the outer peripheral surface 50a of the plug 50 and the inner peripheral surface 24a of the plug arrangement hole 24. The seal band 21a, the small circular protrusion 21b, the FR mounting surface 26, and the like on the upper surface of the ceramic plate 20 may be formed before or after the plug 50 is press-fitted into the plug arrangement hole 24.

[0027] Prior to the above-described manufacturing process, an adjustment process may be performed in which the plug 50 is press-fitted into the plug arrangement hole 24 of the ceramic plate 20 before bonding to the base plate 30, and the reference surface 21c of the ceramic plate 20 and the upper surface 56 of the plug 50 are aligned by machining such as polishing or grinding. After the adjustment process, the plug 50 is removed from the plug arrangement hole 24 of the ceramic plate 20 by punching or the like, and the adjusted ceramic plate 20 and plug 50 are used in the above-described manufacturing process, thereby further improving the positional accuracy (particularly the vertical positional accuracy) of the plug 50 in the plug arrangement hole 24.

[0028] In the above-described wafer mounting table 10, if a defect occurs in the plug 50, rework may be performed to replace the plug 50 with a new plug 50. Rework is performed, for example, by removing the plug 50 from the plug arrangement hole 24 while the base plate 30 remains bonded to the ceramic plate 20, and then press-fitting a new plug 50 into the plug arrangement hole 24. A simple method for removing the plug 50 from the plug arrangement hole 24 is to adhere the upper surface 56 of the plug 50 to a removal jig or the like with an adhesive and extract it toward the wafer mounting surface 21. Because the withstand load of the adhesive is low, for example, 100 N or less, it is desirable that the plug 50 be able to be extracted from the plug arrangement hole 24 with an extraction load (extraction strength) lower than the withstand load of the adhesive. As in Patent Document 1, even when the plug and the plug placement hole have the same shape, if the press-fit load (press-fit strength) when the plug is pressed into the plug is reduced, the removal load required to extract the plug toward the wafer placement surface is also reduced. However, if the press-fit load is too low, the plug may not be pressed into the desired depth (vertical position). Also, as in Patent Document 1, when the plug and the plug placement hole have the same shape, the plug may be pressed into the desired depth by increasing the press-fit load when the plug is pressed into the plug. However, if the press-fit load is too high, the plug may not be removed. In contrast, in the wafer placement table 10 described above, the outer peripheral surface 50 a of the plug 50 is more gently inclined than the inner peripheral surface 24 a of the plug placement hole 24, so that the plug 50 can be easily removed even when the plug 50 is pressed into the plug placement hole with a relatively high press-fit load.

[0029] As described above, the wafer mounting table 10 allows the plug 50 to be easily removed even when the plug 50 is press-fitted with a relatively high press-fit load. The reason for this effect is presumably as follows: The outer peripheral surface 50 a of the plug 50 is more gently inclined than the inner peripheral surface 24 a of the plug placement hole 24, so it is believed that the plug 50 is primarily fitted into the large-diameter upper portion of the plug placement hole 24. Because the ceramic plate 20 is thick and less likely to deform in this portion, it is presumed that even when the plug 50 is press-fitted with a relatively high press-fit load, the fitting strength for fitting the plug 50 is not too high, and the plug 50 can be easily removed. The plug 50 is fixed in the plug placement hole 24 by fitting, and can be fixed to the plug placement hole 24 without using an adhesive.

[0030] Furthermore, if the difference (θ-α) obtained by subtracting the inclination angle α of the outer peripheral surface 50a of the plug 50 from the inclination angle θ of the inner peripheral surface 24a of the plug placement hole 24 is set to 0.2° or less, the gap between the outer peripheral surface 50a of the plug 50 and the inner peripheral surface 24a of the plug placement hole 24 can be reduced. If the gap between the outer peripheral surface 50a of the plug 50 and the inner peripheral surface 24a of the plug placement hole 24 is large, discharge may occur in the gap, potentially deteriorating the wafer W. However, reducing this gap can suppress discharge. For example, if the vertical length of the gap is 200 μm or less, discharge can be further suppressed. The opening width of the gap (the radial length when viewed from above) may be set to, for example, 0.7 μm or less.

[0031] Furthermore, if the difference (θ-α) obtained by subtracting the inclination angle α of the outer peripheral surface 50a of the plug 50 from the inclination angle θ of the inner peripheral surface 24a of the plug placement hole 24 is set to be 0.05° or more, the plug 50 can be more easily removed. Furthermore, if this difference is set to be 0.10° or less, the gap between the plug 50 and the ceramic plate 20 can be made smaller, and discharge can be further suppressed.

[0032] Furthermore, if the inclination angle θ of the inner peripheral surface 24a of the plug arrangement hole 24 is set to 70° or more, the opening area on the upper opening side of the plug arrangement hole 24 can be made relatively small, thereby increasing the degree of freedom in design, such as the placement of the small circular protrusions 21b and the electrodes 22. Furthermore, if the inclination angle θ is set to less than 88°, the plug 50 can be inserted into the plug arrangement hole 24 relatively easily.

[0033] The punching strength required to extract the plug 50 toward the wafer mounting surface 21 may be 100 N or less, 75 N or less, or 50 N or less. The smaller the punching strength, the easier it is to remove the plug 50. This punching strength may be, for example, 20 N or more, or 30 N or more. The greater the punching strength, the more likely it is that the plug 50 will be unintentionally removed from the plug placement hole 24. The punching strength may be expressed as a pull-out strength or a punching strength. The punching strength can be measured, for example, as follows. FIG. 5 illustrates an example of a method for measuring the punching strength. A compression tester 70 is used to measure the punching strength. The compression tester 70 includes a base 71, a cover plate 72, and a punching pin 73 (cylindrical with a tip diameter of 3 mm) that can move up and down at a predetermined speed. The base 71 has a mounting surface 71a on which the test piece 74 is placed and a through-hole 71b into which the plug 50 punched out of the test piece 74 is dropped. The cover plate 72 has an insertion hole 72a through which a punching pin 73 is inserted vertically. The test piece 74 is a ceramic plate 20 with a plug 50 placed in the plug placement hole 24. The ceramic plate 20 described in the embodiment may be used as is, or may be processed for measurement. The test piece 74 is placed on the mounting surface 71a of the base 71 with the lower opening of the plug placement hole 24 facing up and the upper opening facing down, and is fixed by being sandwiched from above with the cover plate 72. At this time, the through-hole 71b of the base 71, the plug placement hole 24 of the test piece 74, and the insertion hole 72a of the cover plate 72 are coaxially arranged. Next, the punching pin 73 is moved downward from above the cover plate 72 at a speed of 1 mm / min to punch the plug 50 out of the test piece 74. The load applied when punching the test piece 74 is continuously measured, and the maximum load measured is taken as the punching strength. As a method for measuring the pull-out strength, any measurement method that can obtain results equivalent to those of the above-mentioned method for measuring the punching strength can be appropriately used.

[0034] Furthermore, because the outer peripheral surface 50a (dense portion 52) of the plug 50 is dense, the plug is less likely to crack during fitting than if the outer peripheral surface 50a of the plug were porous, and the fitting strength can be further increased by tight contact with the inner peripheral surface 24a of the plug placement hole 24. Furthermore, because the vent portion 54 of the plug 50 is porous, the effective path length within the vent portion 54 is longer than if the vent portion 54 were hollow, making it less likely for discharge to occur within the vent portion 54.

[0035] It goes without saying that the present invention is not limited to the above-described embodiment, and can be embodied in various forms as long as they fall within the technical scope of the present invention.

[0036] In the above-described embodiment, the seal band 21 a and the small circular protrusions 21 b are formed on the wafer mounting surface 21, but the seal band 21 a and the small circular protrusions 21 b do not have to be formed. The wafer mounting surface 21 may be, for example, a flat surface (only the reference surface 21 c).

[0037] In the above-described embodiment, the top surface 56 of the plug 50 is flush with the reference surface 21c, but this is not intended to be limiting. Examples are shown in FIGS. 6 and 7 . In FIGS. 6 and 7 , the same components as those in the above-described embodiment are denoted by the same reference numerals, and their description will be omitted. As shown in FIG. 6 , the top surface 56 of the plug 50 may be recessed relative to the reference surface 21c. In this case, the amount of recession relative to the reference surface 21c is preferably small, e.g., 0.2 mm or less, from the viewpoint of suppressing discharge within the plug placement hole 24. As shown in FIG. 7 , the top surface 56 of the plug 50 may be convex relative to the reference surface 21c. In this case, the top surface 56 of the plug 50 is preferably positioned lower than the top surfaces of the seal band 21a and the small circular protrusions 21b. In this case, the amount of protrusion relative to the reference surface 21c is preferably small from the viewpoint of suppressing a decrease in electrostatic adsorption force.

[0038] In the above-described embodiment, the plug 50 having a dense portion 52 and a porous vent portion 54 vertically penetrating the dense portion 52 has been described as an example of a plug that allows gas to flow vertically. However, the present invention is not limited to this. For example, a plug 350 shown in FIG. 8 or a plug 450 shown in FIG. 9 may be used instead of the plug 50. In FIGS. 8 and 9, the same components as those in the above-described embodiment are denoted by the same reference numerals, and their description will be omitted. FIG. 8A is a longitudinal cross-sectional view of the plug 350, and FIG. 8B is a plan view of the plug 350. Here, the plug 350 is a ceramic member such as alumina or aluminum nitride, and is formed of, for example, the same material as the ceramic plate 20. The plug 350 has a dense portion 352 and one or more (here, one) vent holes 354 vertically penetrating the dense portion 352. In FIG. 8 , the vent hole 354 is shown as penetrating the dense portion 352 in the vertical direction while bending, but it may be straight or spiral. Furthermore, at least a portion of the vent hole 354 may be porous. Two or more vent holes 354 may be provided. FIG. 9A is a longitudinal cross-sectional view of the plug 450 (a cross-sectional view taken along line A-A in FIG. 9B ), FIG. 9B is a plan view of the plug 450, and FIG. 9C is a cross-sectional view taken along line C-C in FIG. 9B . Here, the plug 450 is a ceramic member such as alumina or aluminum nitride, and is formed, for example, from the same material as the ceramic plate 20. The plug 450 has a dense dense portion 452 and one or more (four in this example) vent grooves 454 formed along the outer peripheral surface 50 a of the dense portion 452, extending from the lower end to the upper end of the plug 450. In this plug 450, the outer peripheral surface 50a of the plug 450 is more gently inclined than the inner peripheral surface 24a of the plug placement hole 24 except for the portion where the ventilation groove 454 is formed. Therefore, as in the above-described embodiment, the plug 450 can be easily removed even if the plug 450 is press-fitted with a relatively high press-fit load. Although the ventilation groove 454 has a straight shape in FIG. 9, it may be formed so as to bend from the lower end to the upper end of the plug 450, or may be spiral. Furthermore, at least a portion of the ventilation groove 454 may be porous.

[0039] In the above-described embodiment, the plug arrangement hole 24 and the plug 50 have a truncated cone shape, but the shape is not particularly limited to this. For example, the plug arrangement hole and the plug may have a truncated pyramid shape. In this case, the "diameters" of the upper and lower openings of the plug arrangement hole 24 and the upper and lower surfaces 56 and 58 of the plug 50 described above may be interpreted as "diameters equivalent to a circle with equal area." The same applies to the plug 350 and the plug 450.

[0040] In the above-described embodiment, the plug 50 is an electrically insulating member, but is not limited to this. For example, the plug 50 may be a conductive member formed of a conductive ceramic or the like. The same applies to the plugs 350 and 450. The conductive plug serves to prevent a potential gradient from occurring within the plug placement hole 24 of the ceramic plate 20, thereby suppressing discharge within the plug placement hole 24.

[0041] In the above-described embodiment, through holes are provided as the plug placement holes 24, extending from the lower surface of the ceramic plate 20 to the wafer mounting surface 21. However, instead of or in addition to this, through holes may be provided from the lower surface of the ceramic plate 20 to the FR mounting surface 26. In this case, the through holes extending from the lower surface of the ceramic plate 20 to the FR mounting surface 26 may be provided at multiple locations (for example, multiple locations equally spaced along the circumferential direction) so as to open onto the FR mounting surface 26 of the ceramic plate 20.

[0042] In the above-described embodiment, wafer mounting table 10 having wafer mounting surface 21 and FR mounting surface 26 has been described as an example of the semiconductor manufacturing equipment member of the present invention, but wafer mounting table 10 does not have to have FR mounting surface 26. Furthermore, the semiconductor manufacturing equipment member of the present invention may also be a focus ring mounting table having FR mounting surface 26 but no wafer mounting surface.

[0043] In the above-described embodiment, the electrode 22 is arranged at a position corresponding to the wafer mounting surface 21, but instead of or in addition to this, it may be arranged at a position corresponding to the FR mounting surface 26.

[0044] In the above-described embodiment, an electrostatic electrode is exemplified as the electrode 22 built into the ceramic plate 20, but this is not particularly limited. For example, instead of or in addition to the electrode 22, a heater electrode (resistive heating element) or an RF electrode may be built into the ceramic plate 20.

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

[0046] In the above-described embodiment, the base plate 30 is provided with gas holes 34 forming a gas supply path, but this is not particularly limited. For example, as shown in FIG. 10 , 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 that introduces gas from the back surface of the base plate 30 into the ring portion 64a, and a distributor portion 64c that distributes gas from the ring portion 64a to each plug 50. In FIG. 10 , the same components as those in the above-described embodiment are denoted by the same reference numerals. The number of inlet portions 64b may be less than the number of distributor portions 64c, for example, one. This allows the number of external gas pipes connected to the underside of the base plate 30 to be less than the number of plugs 50. Such a configuration may also be employed in the wafer mounting table 110 or the wafer mounting table 210.

[0047] In the above-described embodiment, the wafer mounting table 10 includes the ceramic plate 20, the plug placement hole 24, the base plate 30, the metal bonding layer 40, and the plug 50. However, other components are not particularly limited as long as the wafer mounting table 10 includes the ceramic plate 20, the plug placement hole 24, and the plug 50. For example, the wafer mounting table 10 does not need to include the metal bonding layer 40 or the base plate 30. The same applies to the focus ring mounting table.

[0048] Hereinafter, specific examples of fabricating semiconductor manufacturing equipment members according to the present invention will be described as examples. Experimental Examples 1 and 2 correspond to Examples, and Experimental Example 3 corresponds to a Comparative Example.

[0049] Experimental Example 1: A ceramic plate made of alumina and 3.6 mm thick was prepared. The ceramic plate had a plug placement hole with a lower opening diameter of 3.5 mm and a tapered hole with an inner peripheral surface inclination angle θ of 85.00°. A plug made of alumina and 3.6 mm thick was also prepared. The plug had an outer peripheral surface inclination angle α of 84.95° and a dense outer peripheral surface (porosity of 1.0% or less). A plug was inserted into the upper opening of the plug placement hole and pressed in at a press-fit strength of 100 N, 300 N, or 500 N. Five specimens were prepared for each press-fit strength, for a total of 15 specimens. The press-fit depth of each specimen was measured using a height gauge, and the change in press-fit depth relative to a 500 N press-fit was determined. The press-fit depth was the vertical distance from the wafer mounting surface to the top surface of the plug. The press-fit depth was smaller the higher the plug top surface. Thereafter, the punching strength of each test piece was measured by the punching strength measuring method described above. Note that the compression tester used was an Instron Universal Testing Machine Model 5566.

[0050] Experimental Example 2 The same procedure as in Experimental Example 1 was conducted except that a plug having an inclination angle α of the outer peripheral surface of 84.90° was used.

[0051] Experimental Example 3 The same procedure as in Experimental Example 1 was conducted except that a plug having an inclination angle α of the outer peripheral surface of 85.00° was used.

[0052] [Experimental Results] The relationship between press-fit strength and punching strength for Experimental Examples 1 to 3 is summarized in FIG. 11 and Table 1. FIG. 11 and Table 1 also summarize the relationship between press-fit strength and the change in press-fit depth with respect to a 500 N press-fit. As shown in FIG. 11 and Table 1, it was found that, at any press-fit strength, the punching strength was lower when the outer peripheral surface of the plug was more gently inclined than the inner peripheral surface of the plug placement hole than when the inclination was not more gently, and the plug could be easily removed. Furthermore, in Experimental Examples 1 to 3, the press-fit depth could be adjusted by changing the press-fit strength, but the effect of the press-fit strength on the punching strength was smaller when the outer peripheral surface of the plug was more gently inclined than the inner peripheral surface of the plug placement hole than when the inclination was not more gently inclined. This shows that by making the outer peripheral surface of the plug more gently inclined than the inner peripheral surface of the plug placement hole, it is possible to improve the positional accuracy of the plug while also facilitating plug removal. In particular, it was found that in Experimental Examples 1 and 2, a punching strength of 75 N or less could be achieved with a press-fitting strength of 500 N, and a punching strength of 50 N or less could be achieved with a press-fitting strength of 300 N, making it possible to more easily remove the plug. Furthermore, it was found that in Experimental Examples 1 and 2, even when the plug was press-fitted at 500 N, the plug could be removed with a punching strength that was 5 times or less (for example, 4.5 times or less or 4 times or less) the pullout strength when the plug was press-fitted at 100 N. Furthermore, it was found that in Experimental Examples 1 and 2, the change in the press-fitting depth when the plug was press-fitted at 100 N relative to the press-fitting depth when the plug was press-fitted at 500 N could be kept within −0.025 mm or −0.02 mm.

[0053]

[0054] This application claims priority from Japanese Patent Application No. 2024-107428, filed on July 3, 2024, the entire contents of which are incorporated herein by reference.

[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.

[0056] REFERENCE SIGNS LIST 10 wafer mounting table, 20 ceramic plate, 21 wafer mounting surface, 21a seal band, 21b small circular protrusion, 21c reference surface, 22 electrode, 24 plug placement hole, 24a inner peripheral surface, 26 focus ring mounting 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 outer peripheral surface, 52 dense portion, 54 ventilation portion, 56 upper surface, 58 lower surface, 60 focus ring, 62 circumferential groove, 64a ring portion, 64b introduction portion, 64c distribution portion, 70 compression tester, 71 base, 71a mounting surface, 71b through hole, 72 cover plate, 72a insertion hole, 73 punching pin, 74 test piece, 90 Metallic bonding material, 92 through hole, 94 bonded body, 110 wafer mounting table, 210 wafer mounting table, 350 plug, 352 dense portion, 354 ventilation hole, 450 plug, 452 dense portion, 454 ventilation groove, 510 wafer mounting table, W wafer, α tilt angle, θ tilt angle.

Claims

1. A ceramic plate having at least one of a wafer mounting surface and a focus ring mounting surface on its upper surface, The aforementioned ceramic plate has a plug placement hole that penetrates vertically and has a tapered inner surface that narrows towards the bottom, A plug that fits into the aforementioned plug placement hole, has a tapered outer surface that narrows towards the bottom, and allows gas to flow in the vertical direction, Equipped with, A component for semiconductor manufacturing equipment, wherein the outer surface of the plug is less sloped than the inner surface of the plug placement hole.

2. The semiconductor manufacturing apparatus component according to claim 1, wherein the difference obtained by subtracting the inclination angle α of the outer surface of the plug from the inclination angle θ of the inner surface of the plug placement hole is 0.2° or less.

3. The semiconductor manufacturing apparatus component according to claim 1, wherein the difference obtained by subtracting the inclination angle α of the outer surface of the plug from the inclination angle θ of the inner surface of the plug placement hole is 0.05° or more and 0.10° or less.

4. The semiconductor manufacturing apparatus component according to any one of claims 1 to 3, wherein the inclination angle θ of the inner circumferential surface of the plug arrangement hole is 70° or more and less than 88°.

5. The semiconductor manufacturing apparatus component according to any one of claims 1 to 3, wherein the pull-out strength required to pull the plug out toward the wafer mounting surface is 100 N or less.

6. A semiconductor manufacturing apparatus component according to any one of claims 1 to 3, A conductive substrate is bonded to the lower surface of the ceramic plate and provided with a gas supply passage that communicates with the plug placement hole, A component for semiconductor manufacturing equipment, equipped with the following features.

7. The ceramic plate has an electrode built in, the semiconductor manufacturing apparatus component according to any one of claims 1 to 3.

8. The component for semiconductor manufacturing apparatus according to any one of claims 1 to 3, wherein the plug is press-fitted into the plug placement hole.

9. The semiconductor manufacturing apparatus component according to any one of claims 1 to 3, excluding the case in which the plug and the plug placement hole are bonded together with an adhesive layer.