Components for semiconductor manufacturing equipment

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

Technical Field

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

Background Art

[0002] Conventionally, in a semiconductor manufacturing apparatus, a member for a semiconductor manufacturing apparatus including a ceramic plate having a wafer placement surface on its upper surface has been used. For example, the member for a semiconductor manufacturing apparatus of Patent Document 1 includes a plug placement hole penetrating the ceramic plate in the vertical direction, and a plug that is placed in the plug placement hole and allows gas to flow in the vertical direction. The plug is, for example, in the shape of an inverted frustum of a cone with an upper base larger than a lower base, and is placed in a plug placement hole having a shape corresponding thereto.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the above-described member for a semiconductor manufacturing apparatus, the plug is adhered to the plug placement hole with an adhesive, but the inventors of the present invention considered press-fitting and fitting the plug into the plug placement hole. In that case, in order to press-fit the plug to a desired depth, a relatively high press-fitting load may be required. However, when the press-fitting load is increased, the fitting strength becomes too high, and when performing rework to replace the plug with a new plug, the plug may not be removable.

[0005] The present invention has been made to solve such problems, and a main object thereof is to enable easy removal of the plug even when the plug is press-fitted with a relatively high press-fitting load.

Means for Solving the Problems

[0006] [1] The semiconductor manufacturing apparatus component of the present invention is 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, The outer surface of the plug is less sloped than the inner surface of the plug mounting hole.

[0007] In this semiconductor manufacturing equipment component, a plug having a tapered outer surface that tapers towards the bottom is fitted into a plug placement hole having a tapered inner surface that tapers towards the bottom, and the outer surface of the plug is less sloped than the inner surface of the plug placement hole. Therefore, even if the plug is pressed in with a relatively high press-fitting load, it can be easily removed. The reason for this effect can be inferred as follows: Since the outer surface of the plug is less sloped than the inner surface of the plug placement hole, it is thought that the plug is mainly fitted into the upper, larger diameter portion of the plug placement hole. In this portion, the ceramic plate is thick and does not deform easily, so even if the plug is pressed in with a relatively high press-fitting load, the fitting strength of the plug does not become too high, and it is inferred that the plug can be easily removed.

[0008] In this specification, the present invention may be described using terms such as up and down, left and right, front and back, but up and down, left and right, and front and back are merely relative positional relationships. Therefore, when the orientation of a semiconductor manufacturing equipment component is changed, up and down may become left and right, or left and right may become up and down, but such cases are also included within the technical scope of the present invention.

[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 surface of the plug from the inclination angle θ of the inner surface of the plug mounting hole may be 0.2° or less. If this difference is 0.2° or less, the gap between the outer surface of the plug and the inner surface of the plug mounting hole can be reduced. In this specification, the inclination angle α of the outer surface of the plug is defined as the angle between a plane perpendicular to the axis of the plug and the outer surface of the plug (where 0° < α < 90°). Also, the inclination angle θ of the inner surface of the plug mounting hole is defined as the angle between a plane perpendicular to the axis of the plug mounting hole and the inner surface of the plug mounting 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 surface of the plug from the inclination angle θ of the inner 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 removed more easily. 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 component described above (the semiconductor manufacturing equipment component described in any of [1] to [3] above), the inclination angle θ of the inner circumferential surface of the plug placement hole may be 70° or more and less than 88°.

[0012] [5] In the semiconductor manufacturing equipment component described above (the semiconductor manufacturing equipment component described in any 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 above-described member for a semiconductor manufacturing apparatus (the member for a semiconductor manufacturing apparatus described in any one of [1] to [5] above) may further include a conductive substrate joined to the lower surface of the ceramic plate and provided with a gas supply passage communicating with the plug arrangement holes. The conductive substrate may be used, for example, as a cooling plate for cooling the ceramic plate, or as a high-frequency electrode (RF electrode) for generating plasma above the wafer placement surface.

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

Brief Description of the Drawings

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

Embodiments for Carrying Out the Invention

[0016] A preferred embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view of a wafer stage 10 which is an example of a member for a semiconductor manufacturing apparatus according to the present invention, 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 stage 10 includes a ceramic plate 20, a plug placement hole 24, a base plate (conductive base material) 30, a metal bonding layer 40, and a plug 50.

[0018] The ceramic plate 20 is a ceramic disc (e.g., 300 mm in diameter) made of an alumina sintered body or an aluminum nitride sintered body. The ceramic plate 20 is preferably dense. Dense means that the porosity is 5% or less (preferably 3% or less, more preferably 1% or less). The porosity of the ceramic plate 20 is the open porosity measured according to 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 a wafer mounting surface 21 and a focus ring (FR) mounting surface 26 on its upper surface. The wafer mounting surface 21 is a circular surface on which the wafer W is placed. As shown in Figure 2, a seal band 21a is formed along the outer edge of the wafer mounting surface 21, and a plurality of small circular protrusions 21b are formed on the entire surface. The seal band 21a and the small circular protrusions 21b are of the same height, and their height is, for example, several μm to several tens of μm. The portion of the wafer mounting surface 21 that does not have 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 placed on the FR mounting surface 26. The focus ring 60 is made of, for example, Si. A circumferential groove 62 is provided above the inner surface of the focus ring 60 so as not to come into 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 placed on the FR mounting surface 26 in an overhanging state, extending beyond the outside of the wafer mounting base 10. The ceramic plate 20 incorporates electrodes 22. The electrodes 22 are planar mesh electrodes used as electrostatic electrodes, and a DC voltage can be applied to them. When a DC voltage is applied to 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 circular protrusion 21b) by electrostatic attraction force, and when the application of the DC voltage is removed, the attraction and fixation of the wafer W to the wafer mounting surface 21 is released.

[0019] The plug placement hole 24 is a hole that penetrates the ceramic plate 20 in the vertical direction, and in this case, it is a through hole from the lower surface of the ceramic plate 20 to the wafer mounting surface 21. The plug placement hole 24 is opposite to the gas hole 34 of the base plate 30. The plug placement hole 24 penetrates the electrode 22 in the vertical direction, but the electrode 22 is not exposed on the inner circumferential surface of the plug placement hole 24. The plug placement hole 24 is a tapered hole having a frustoconical space in which the area of ​​the upper opening is larger than the area of ​​the lower opening, and has a tapered inner circumferential surface 24a that tapers towards the bottom. The inclination angle θ of the inner circumferential surface 24a of the plug placement hole 24 (see Figure 3) is, for example, 70° or more and less than 88°, preferably 75° or more and 87° or less. As shown in Figure 2, the plug placement hole 24 is provided at multiple locations (for example, at multiple locations provided at equal intervals 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, for example, between 1 mm and 5 mm.

[0020] The base plate 30 is a conductive disc with good thermal conductivity (a disc with the same diameter as or larger than the ceramic plate 20). Inside the base plate 30, a refrigerant channel 32 through which a refrigerant (for example, an electrically insulating liquid such as a fluorine-based inert liquid) circulates and a gas hole 34 for supplying gas to the plug 50 are formed. The gas hole 34 is provided to penetrate the base plate 30 in the vertical direction and has a large diameter portion 34a at the top. In a plan view, the large diameter portion 34a encompasses the lower opening of the plug placement hole 24. In a plan view, the refrigerant channel 32 is formed in a continuous line from the inlet to the outlet across the entire surface of the base plate 30. Examples of materials for the base plate 30 include metals and composite materials. Examples of metals include Mo. Examples of composite materials include metal-ceramic composites. Examples of metal-ceramic composites include metal matrix composites (MMCs) and ceramic matrix composites (CMCs). Specific examples of such composite materials include materials containing Si, SiC, and Ti, and materials in which Al and / or Si are impregnated into a porous SiC body. Materials containing Si, SiC, and Ti are called SiSiCTi, materials in which Al is impregnated into a porous SiC body are called AlSiC, and materials in which Si is impregnated into a porous SiC body are called SiSiC. It is preferable to select a material for the base plate 30 that has a similar coefficient of thermal expansion to 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 placed above the wafer mounting surface 21, and when high-frequency power is applied between the upper electrode and the base plate 30, which are parallel plate electrodes, plasma is generated.

[0021] The metal bonding layer 40 joins the lower surface of the ceramic plate 20 to the upper surface of the base plate 30. The metal bonding layer 40 is formed, for example, by TCB (Thermal Compression Bonding). TCB is a known method in which a metal bonding material is sandwiched between two members to be joined, and the two members are pressurized and joined while heated to a temperature below the solidus temperature of the metal bonding material. The metal bonding layer 40 may also be a layer formed of solder or metal brazing material. The metal bonding layer 40 has a through hole 42. The through hole 42 is provided at a position opposite 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, "coaxial" includes not only cases where they are perfectly coaxial, but also cases where they are substantially coaxial (for example, when they are within tolerance) (the same applies hereinafter). Furthermore, in this specification, "identical" includes not only exact agreement but also substantial agreement (for example, falling within the 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 in the vertical direction. Here, the plug 50 is a ceramic member such as alumina or aluminum nitride, and is formed from the same material as, for example, the ceramic plate 20. The plug 50 has a dense portion 52 made of a dense material and a porous ventilation portion 54 that penetrates the dense portion 52 in the vertical direction. The dense portion is assumed to have 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: The image is observed with an SEM (scanning electron microscope) at a magnification of 3000x, and the brightness distribution of the obtained SEM image is binarized into a material portion and a porous portion by Otsu's binarization, and the area ratio of the porous portion to the whole is calculated as the porosity. The ventilation portion 54 is formed from a porous body made of, for example, the same material as the dense portion 52. The porous material shall have a porosity greater than 5% but less than 100%. The porosity of the ventilation 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 the mercury intrusion method (JIS R1655:2003). The plug 50 is a frustoconical member in which the area of ​​the upper surface 56 (see Figure 3) is larger than the area of ​​the lower surface 58 (see Figure 3), and has a tapered outer surface 50a that tapers towards the bottom. The outer surface 50a of the plug 50 is less sloped than the inner surface 24a of the plug placement hole 24. In other words, the inclination angle α (see Figure 3) of the outer surface 50a of the plug 50 is greater than the inclination angle α of the plug placement hole 2 The angle of inclination θ of the inner circumferential surface 24a of 4 is smaller than the angle of inclination θ of the inner circumferential surface 24a of 4. The difference (θ-α) obtained by subtracting the angle of inclination α of the outer circumferential surface 50a of the plug 50 from the angle of inclination θ of the inner circumferential surface 24a of the plug placement hole 24 may be, for example, 0.2° or less, 0.03° or more and 0.15° or less, or 0.05° or more and 0.10° or less. The upper surface 56 of the plug 50 is exposed to the upper opening of the plug placement hole 24 and is arranged in the same plane as the reference surface 21c. In this specification, "identical" includes not only cases where they are completely identical, but also cases where they are substantially identical (for example, cases where they fall within tolerance) (the same applies hereinafter). The plug 50 and the plug placement hole 24 are designed so that when the plug 50 is inserted into the plug placement hole 24 and pressed in with a predetermined press-fitting strength, the height of the upper surface 56 of the plug 50 matches 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 placed 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 using the wafer mounting stand 10 configured in this way will be described. First, with the wafer mounting stand 10 installed in a chamber (not shown), the wafer W is placed on the wafer mounting surface 21. Then, the pressure inside the chamber is reduced using a vacuum pump to adjust to a predetermined vacuum level, and a DC voltage is applied to the electrode 22 of the ceramic plate 20 to generate electrostatic adsorption force, thereby adsorbing and fixing the wafer W to the wafer mounting surface 21 (specifically, the upper surface of the seal band 21a and the upper surface of the circular protrusion 21b). Next, the inside of the chamber is made into a reaction gas atmosphere at a predetermined pressure (for example, several tens to several hundreds of Pa), and in this state, a high-frequency voltage is applied between an upper electrode (not shown) provided on the ceiling of the chamber and the base plate 30 of the wafer mounting stand 10 to generate plasma. The surface of the wafer W is treated by the generated plasma. A refrigerant is circulated in the refrigerant channel 32 of the base plate 30. Backside gas is introduced into the gas hole 34 from a gas cylinder (not shown). A thermal conductive gas (for example, helium) is used as the backside gas. The backside gas is supplied and sealed into the space between the back surface of the wafer W and the reference surface 21c of the wafer mounting surface 21 through the gas hole 34, the through hole 42, and the plug 50. The presence of this backside gas allows for efficient heat conduction between the wafer W and the ceramic plate 20. In addition, the presence of the electrically insulating plug 50 placed in the plug placement hole 24 increases the creepage distance between the wafer W and the base plate 30, thereby suppressing the occurrence of discharge within the plug placement hole 24.

[0024] Next, a manufacturing example of the wafer mounting stage 10 will be described based on Figure 4. Figure 4 is a manufacturing process diagram of the wafer mounting stage 10. First, a ceramic plate 20, a base plate 30, and a metal bonding material 90 are prepared (Figure 4A). The ceramic plate 20 has an electrode 22 built in and is provided with a plug placement hole 24. The plug placement hole 24 has a tapered inner circumferential surface 24a that tapers towards the bottom. The inclination angle θ of the inner circumferential surface 24a of the plug placement hole 24 is, for example, 70° or more and less than 88°. The base plate 30 is provided with a refrigerant flow path 32 and a gas hole 34. The gas hole 34 has a large diameter portion 34a at the top. The metal bonding material 90 is provided with a through hole 92 at a position opposite the large diameter portion 34a of the gas hole 34.

[0025] Next, a metal bonding material 90 is sandwiched between the lower surface of the ceramic plate 20 and the upper surface of the base plate 30 to form a laminate. At this time, the laminate is stacked so that the plug placement holes 24 of the ceramic plate 20, the through holes 92 of the metal bonding material 90, and the gas holes 34 of the base plate 30 are coaxial. The laminate is then pressed and bonded at a temperature below the solidus temperature of the metal bonding material 90 (for example, between a temperature 20°C below the solidus temperature and the solidus temperature), and then returned to room temperature (TCB). As a result, the metal bonding material 90 and the through holes 92 become the metal bonding layer 40 and the through holes 42, respectively, and a bonded body 94 is obtained in which the ceramic plate 20 and the base plate 30 are bonded by the metal bonding layer 40 (Figure 4B). Note that Al-Mg-based bonding materials or Al-Si-Mg-based bonding materials can be used as the metal bonding material 90. It is preferable to use a metal bonding material 90 with a thickness of about 100 μm.

[0026] Next, a frustoconical plug 50 is prepared (Figure 4B). The plug 50 has a dense portion 52 made of dense material and a porous ventilation portion 54 that penetrates the dense portion 52 in the vertical direction. The plug 50 has a tapered outer surface 50a that tapers towards the bottom, and the inclination angle α of the outer surface 50a of the plug 50 is smaller than the inclination angle θ of the inner surface 24a of the plug placement hole 24. In a predetermined range on the upper end side (for example, at least a range of 0.2 mm from the top), the outer diameter of the plug 50 is slightly larger (for example, by only 20 μm or less) than the inner diameter at the corresponding position in the plug placement hole 24 (a position where the plug 50 is fitted into the plug placement hole 24 and they are at the same height). 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 pressed into the plug placement hole 24 with a predetermined press-fitting strength (the load applied to the plug 50 during press-fitting) (Figure 4C). The press-fitting strength is, for example, 100N to 700N. Due to the press-fitting, the ceramic plate 20 around the inner circumferential surface 24a of the plug placement hole 24, especially the upper part, deforms, and the plug 50 around the outer circumferential surface 50a, especially the upper part, also deforms. The plug 50 is fitted into the plug placement hole 24 by the deformation of the ceramic plate 20 and the plug 50 in this way. The plug 50 and the plug placement hole 24 are deformed by the press-fitting, but it is sufficient that the inclination angle θ is greater than the inclination angle α in the state before press-fitting. In addition, since the deformation due to press-fitting is considered to be small in the lower part of the plug 50 and the lower part of the ceramic plate 20, the inclination angle α, inclination angle θ, and angle difference θ-α may be determined in the pressed-fitted state. In this case, for example, the inclination angle α, inclination angle θ, and angle difference θ-α can be determined by checking the lower gap between the outer circumferential surface 50a of the plug 50 and the inner circumferential surface 24a of the plug placement hole 24 using X-ray CT. The seal band 21a, circular small protrusions 21b, FR mounting surface 26, etc. on the upper surface of the ceramic plate 20 may be formed before press-fitting the plug 50 into the plug placement hole 24, or they may be formed after press-fitting the plug 50 into the plug placement hole 24.

[0027] Prior to the manufacturing process described above, the plug 50 may be press-fitted into the plug placement hole 24 of the ceramic plate 20 before it is joined to the base plate 30, and adjustment processing may be performed to align the reference surface 21c of the ceramic plate 20 with the upper surface 56 of the plug 50 by machining such as polishing or grinding. After the adjustment processing, the plug 50 can be removed from the plug placement hole 24 of the ceramic plate 20 by punching or other means, and the ceramic plate 20 and plug 50 after the adjustment processing can be used in the manufacturing process described above to further improve the positional accuracy of the plug 50 in the plug placement hole 24 (especially the positional accuracy in the vertical direction).

[0028] In the wafer mounting table 10 described above, if a problem occurs with the plug 50, rework may be performed to replace the plug 50 with a new one. Rework is performed, for example, by removing the plug 50 from the plug placement hole 24 while the base plate 30 is still bonded to the ceramic plate 20, and then press-fitting a new plug 50 into the plug placement hole 24. A simple method for removing the plug 50 from the plug placement hole 24 is to attach the top surface 56 of the plug 50 to a pull-out jig with adhesive and pull it out towards the wafer mounting surface 21. Since the load capacity of the adhesive is low, for example, 100N or less, it is desirable that the plug 50 can be removed from the plug placement hole 24 with a pull-out load (pull-out strength) lower than the load capacity of the adhesive. As described in Patent Document 1 above, even when the plug and the plug placement hole have the same shape, lowering the press-fitting load (press-fitting strength) when pressing in the plug will also lower the extraction load required to remove the plug from the wafer mounting surface. However, if the press-fitting load is too low, it may not be possible to press-fit the plug to the desired depth (vertical position). Also, as described in Patent Document 1, when the plug and the plug placement hole have the same shape, increasing the press-fitting load when pressing in the plug may allow the plug to be pressed to the desired depth. However, if the press-fitting load is too high, it may not be possible to remove the plug. In contrast, in the wafer mounting table 10 described above, the outer circumferential surface 50a of the plug 50 is less sloped than the inner circumferential surface 24a of the plug placement hole 24. Therefore, even if the plug 50 is pressed in with a relatively high press-fitting load, the plug 50 can be easily removed.

[0029] As described above, with the wafer mounting stage 10, even if the plug 50 is pressed in with a relatively high press-fitting load, the plug 50 can be easily removed. The reason for this effect is presumed to be as follows: Since the outer surface 50a of the plug 50 is less sloped than the inner surface 24a of the plug placement hole 24, it is thought that the plug 50 is mainly fitted into the upper, larger diameter portion of the plug placement hole 24. In this portion, the ceramic plate 20 is thick and does not deform easily, so even if the press-fitting load is relatively high, the fitting strength of the plug 50 does not become too high, and it is presumed that the plug 50 can be easily removed. Furthermore, the plug 50 is fixed in the plug placement hole 24 by fitting, and the plug 50 can be fixed in the plug placement hole 24 without using adhesive.

[0030] Furthermore, if the difference (θ-α) obtained by subtracting the inclination angle α of the outer surface 50a of the plug 50 from the inclination angle θ of the inner surface 24a of the plug placement hole 24 is set to 0.2° or less, the gap between the outer surface 50a of the plug 50 and the inner surface 24a of the plug placement hole 24 can be reduced. Note that if the gap between the outer surface 50a of the plug 50 and the inner surface 24a of the plug placement hole 24 is large, discharge may occur in that gap, potentially altering the wafer W, but by reducing this gap, discharge can be suppressed. 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 (radial length when viewed from above) may be, for example, 0.7 μm or less.

[0031] Furthermore, if the difference (θ-α) obtained by subtracting the inclination angle α of the outer surface 50a of the plug 50 from the inclination angle θ of the inner surface 24a of the plug placement hole 24 is 0.05° or more, the plug 50 can be removed more easily. Also, if this difference is 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 circumferential surface 24a of the plug placement hole 24 is set to 70° or more, the opening area on the upper opening side of the plug placement hole 24 can be made relatively small, thereby increasing the design flexibility for the placement of the circular protrusions 21b and electrodes 22. Also, if this inclination angle θ is less than 88°, the plug 50 can be inserted into the plug placement hole 24 relatively easily.

[0033] The extraction strength required to pull the plug 50 out towards the wafer mounting surface 21 may be 100N or less, 75N or less, or 50N or less. The smaller the extraction strength, the easier it is to remove the plug 50. This extraction strength may be, for example, 20N or more, or 30N or more. The larger the extraction strength, the better it is possible to prevent the plug 50 from unintentionally coming out of the plug placement hole 24. The extraction strength may be a tensile strength or a punching strength. The punching strength can be measured, for example, as follows. Figure 5 illustrates an example of a method for measuring punching strength. A compression tester 70 is used to measure the punching strength. The compression tester 70 is equipped with 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 for dropping the plug 50 punched out of the test piece 74. The cover plate 72 has an insertion hole 72a for inserting the punching pin 73 in the vertical direction. The test piece 74 is a ceramic plate 20 in which the plug 50 is placed in the plug placement hole 24. The ceramic plate 20 described in the embodiment may be used as is, or it 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 upwards and the upper opening facing downwards, and is fixed by sandwiching it 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 arranged coaxially. Next, the punching pin 73 is moved downwards from above the cover plate 72 at a speed of 1 mm / min to punch out the plug 50 from the test piece 74. The load applied when punching out the test piece 74 is continuously measured, and the maximum measured load is defined as the punching strength. For measuring the tensile strength, any measurement method that yields results equivalent to the punching strength measurement method described above can be appropriately adopted.

[0034] Furthermore, because the outer surface 50a (dense portion 52) of the plug 50 is dense, plug cracking is less likely to occur during mating compared to when the outer surface 50a of the plug is porous, and the mating strength can be further increased by closely contacting the inner surface 24a of the plug placement hole 24. In addition, because the ventilation portion 54 of the plug 50 is porous, the effective path length within the ventilation portion 54 is longer than when the ventilation portion 54 is hollow, and discharge is less likely to occur within the ventilation portion 54.

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

[0036] In the embodiments described above, the wafer mounting surface 21 is assumed to have a sealing band 21a and small circular protrusions 21b, but the sealing band 21a and small circular protrusions 21b do not necessarily have to be formed. The wafer mounting surface 21 may be, for example, a flat surface (only the reference surface 21c).

[0037] In the embodiments described above, the upper surface 56 of the plug 50 is assumed to be coplanar with the reference surface 21c, but this is not a limiting factor. Examples are shown in Figures 6 and 7. In Figures 6 and 7, the same reference numerals are used for the same components as in the embodiments described above, and their descriptions are omitted. As shown in Figure 6, the upper surface 56 of the plug 50 may be concave with respect to the reference surface 21c. In this case, from the viewpoint of suppressing discharge within the plug placement hole 24, it is preferable that the amount of concavity with respect to the reference surface 21c be small, preferably 0.2 mm or less. As shown in Figure 7, the upper surface 56 of the plug 50 may be convex with respect to the reference surface 21c. In this case, it is preferable that the upper surface 56 of the plug 50 be positioned lower than the upper surface of the seal band 21a and the upper surface of the small circular protrusion 21b. From the viewpoint of suppressing a decrease in electrostatic attraction force, it is preferable that the amount of convexity with respect to the reference surface 21c of the upper surface 56 of the plug 50 be small.

[0038] In the embodiments described above, a plug 50 having a dense portion 52 made of a dense material and a porous ventilation portion 54 that penetrates the dense portion 52 in the vertical direction was exemplified as a plug that allows gas to flow in the vertical direction, but the invention is not limited to this. For example, instead of plug 50, plug 350 shown in Figure 8 or plug 450 shown in Figure 9 may be used. In Figures 8 and 9, the same reference numerals are used for the same components as in the embodiments described above, and their descriptions are omitted. Figure 8A is a vertical cross-sectional view of plug 350, and Figure 8B is a plan view of plug 350. Here, plug 350 is a ceramic component such as alumina or aluminum nitride, and is formed from the same material as, for example, ceramic plate 20. Plug 350 has a dense portion 352 made of a dense material and one or more (here, one) ventilation holes 354 that penetrate the dense portion 352 in the vertical direction. In Figure 8, the ventilation holes 354 are shown to penetrate the dense portion 352 vertically while bending, but they may be straight or spiral in shape. Also, at least a portion of the ventilation holes 354 may be porous. Furthermore, two or more ventilation holes 354 may be provided. Figure 9A is a longitudinal cross-sectional view of the plug 450 (cross-sectional view AA in Figure 9B), Figure 9B is a plan view of the plug 450, and Figure 9C is a cross-sectional view CC in Figure 9B. Here, the plug 450 is a ceramic component such as alumina or aluminum nitride, and is formed from the same material as, for example, the ceramic plate 20. The plug 450 has a dense portion 452 made of dense material and one or more (four in this case) ventilation grooves 454 formed along the outer peripheral surface 50a of the dense portion 452, extending from the lower end to the upper end of the plug 450. In this plug 450 as well, except for the portion where the ventilation groove 454 is formed, the outer surface 50a of the plug 450 is less sloped than the inner surface 24a of the plug placement hole 24. Therefore, similar to the embodiment described above, even if the plug 450 is pressed in with a relatively high press-fitting load, the plug 450 can be easily removed. In Figure 9, the ventilation groove 454 is shown as a straight shape, but it may be formed to curve from the lower end to the upper end of the plug 450, or it may be spiral. In addition, at least a portion of the ventilation groove 454 may be porous.

[0039] In the embodiment described above, the shapes of the plug placement hole 24 and the plug 50 are truncated cones, but the invention is not limited to this. For example, the shapes of the plug placement hole and the plug may be truncated pyramidal. In that case, the "diameters" of the upper and lower openings of the plug placement hole 24 and the upper and lower surfaces 56 and 58 of the plug 50 should be read as "equivalent diameter of an equal-area circle" and applied accordingly. Plug 350 or The same applies to the Plug 450.

[0040] In the embodiments described above, the plug 50 is made of an electrically insulating material, but it is not limited to this. For example, the plug 50 may be made of a conductive material such as conductive ceramic. The same applies to the plugs 350 and 450. The conductive plugs play a role in preventing a potential gradient from being generated within the plug placement hole 24 of the ceramic plate 20, thereby suppressing discharge inside the plug placement hole 24.

[0041] In the embodiment described above, the plug placement hole 24 is a through hole extending from the lower surface of the ceramic plate 20 to the wafer mounting surface 21. However, instead of this, or in addition, a through hole extending from the lower surface of the ceramic plate 20 to the FR mounting surface 26 may be provided. In that case, the through hole extending from the lower surface of the ceramic plate 20 to the FR mounting surface 26 may be provided at multiple locations (for example, at 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 embodiments described above, a wafer mounting stand 10 having a wafer mounting surface 21 and an FR mounting surface 26 was described as an example of a semiconductor manufacturing apparatus component of the present invention. However, the wafer mounting stand 10 does not necessarily have to have an FR mounting surface 26. Furthermore, the semiconductor manufacturing apparatus component of the present invention may be a focus ring mounting stand that has an FR mounting surface 26 but does not have a wafer mounting surface.

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

[0044] In the embodiments described above, electrostatic electrodes were exemplified as the electrodes 22 embedded in the ceramic plate 20, but the invention is not limited thereto. For example, instead of or in addition to the electrodes 22, heater electrodes (resistive heating elements) or RF electrodes may be embedded in the ceramic plate 20.

[0045] In the embodiment described above, the ceramic plate 20 and the base plate 30 were joined with a metal bonding layer 40, but a resin adhesive layer may be used instead of the metal bonding layer 40.

[0046] In the embodiment described above, the base plate 30 is provided with gas holes 34 that constitute a gas supply path, but the invention is not limited to this. For example, as shown in Figure 10, the base plate 30 may be provided with a ring portion 64a that is concentric with the base plate 30 in plan view, an introduction portion 64b for introducing gas from the back surface of the base plate 30 to the ring portion 64a, and a distribution portion 64c for distributing gas from the ring portion 64a to each plug 50. In Figure 10, the same components as in the embodiment described above are denoted by the same reference numerals. The number of introduction portions 64b may be less than the number of distribution 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 reduced to less than the number of plugs 50. Such a configuration may also be adopted for the wafer mounting table 110 and the wafer mounting table 210.

[0047] In the embodiment described above, the wafer mounting stage 10 is provided with a ceramic plate 20, plug placement holes 24, a base plate 30, a metal bonding layer 40, and a plug 50. However, as long as it includes the ceramic plate 20, plug placement holes 24, and plug 50, the other components are not particularly limited. For example, the metal bonding layer 40 and the base plate 30 may not be included. The same applies to the focus ring mounting stage. [Examples]

[0048] In the following, specific examples of the semiconductor manufacturing equipment components of the present invention will be described as embodiments. Experimental Examples 1 and 2 correspond to embodiments, and Experimental Example 3 corresponds to a comparative example.

[0049] [Experimental Example 1] A ceramic plate made of alumina with a thickness of 3.6 mm was prepared. The ceramic plate had a tapered hole for plug placement, with a lower opening diameter of 3.5 mm and an inner surface inclination angle θ of 85.00°. A plug made of alumina with a thickness of 3.6 mm was also prepared. The plug had an outer surface inclination angle α of 84.95° and its outer surface was dense (porosity of 1.0% or less). The plug was inserted from the upper opening side of the plug placement hole and pressed in with one of three press-fit strengths: 100 N, 300 N, or 500 N. A total of 15 test specimens were prepared, 5 for each press-fit strength. For each test specimen, the press-fit depth was measured using a height gauge, and the change in press-fit depth for 500 N press-fit was determined. The press-fit depth is the vertical length from the wafer mounting surface to the top surface of the plug, and the higher the top surface of the plug, the smaller the press-fit depth. Subsequently, the punching strength of each test specimen was measured using the punching strength measurement method described above. An Instron 5566 universal testing machine was used as the compression testing machine.

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

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

[0052] [Experimental Results] The relationship between press-fit strength and punch-out strength for Experimental Examples 1-3 is summarized in Figure 11 and Table 1. Figure 11 and Table 1 also summarize the relationship between press-fit strength and the change in press-fit depth for a 500N press-fit. As shown in Figure 11 and Table 1, it was found that for all press-fit strengths, making the outer surface of the plug less sloped than the inner surface of the plug placement hole resulted in lower punch-out strength and easier plug removal compared to not having a slope. Furthermore, in Experimental Examples 1-3, the press-fit depth could be adjusted by changing the press-fit strength, but making the outer surface of the plug less sloped than the inner surface of the plug placement hole resulted in less influence of press-fit strength on punch-out strength compared to not having a slope. From this, it was found that making the outer surface of the plug less sloped than the inner surface of the plug placement hole can improve the positional accuracy of the plug while making it easier to remove the plug. In particular, in Experimental Examples 1 and 2, it was found that a punching force of 75N or less could be achieved with a press-fitting force of 500N, and a punching force of 50N or less could be achieved with a press-fitting force of 300N, making it easier to remove the plug. Furthermore, in Experimental Examples 1 and 2, it was found that even when the plug was press-fitted with 500N, the plug could be removed with a punching force of 5 times or less (for example, 4.5 times or less or 4 times or less) than when the plug was press-fitted with 100N. In addition, in Experimental Examples 1 and 2, it was found that the change in the press-fitting depth when the plug was press-fitted with 100N compared to when the plug was press-fitted with 500N could be kept within -0.025mm and -0.02mm, respectively.

[0053] [Table 1]

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

[0055] This invention can be used in wafer mounting stages used in semiconductor manufacturing equipment, such as ceramic heaters, electrostatic chuck heaters, and electrostatic chucks. [Explanation of Symbols]

[0056] 10 Wafer mounting stage, 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 circumferential surface, 26 Focus ring mounting surface, 30 Base plate, 32 Refrigerant flow path, 34 Gas hole, 34a Large diameter section, 40 Metal bonding layer, 42 Through hole, 50 Plug, 50a Outer circumferential surface, 52 Dense section, 54 Ventilation section, 56 Top surface, 58 Bottom surface, 60 Focus ring, 62 Circumferential groove, 64a Ring section, 64b Inlet section, 64c Distribution section, 70 Compression test machine, 71 Base, 71a Mounting surface, 71b Through hole, 72 Cover plate, 72a Insertion hole, 73 Punching pin, 74 Test piece, 90 Metal bonding material, 92 through hole, 94 bonded body, 110 wafer mounting platform, 210 wafer mounting platform, 350 plug, 352 dense section, 354 ventilation hole, 450 plug, 452 dense section, 454 ventilation groove, 510 wafer mounting platform, 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.

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