TWI789770B - Breathable plug, substrate support assembly and shower plate - Google Patents

Abstract

The breathable plug of the present disclosure comprises a honeycomb structure of dense ceramics having multiple through holes in the axial direction.

The substrate support assembly of the present disclosure comprises an electrostatic attraction member and a breathable plug. The electrostatic attraction member has: a substrate made of a plate-shaped ceramic having an attraction surface on which the member to be processed is attracted and a facing surface located opposite to the attraction surface; an internal electrode located within the substrate; and a flow path located along the thickness direction of the base material. The breathable plug was mounted inside the flow path.

Description

Gas permeable pins, substrate support assemblies and spray plates

The present disclosure relates to a gas-permeable plug and a substrate supporting component provided with the gas-permeable plug.

Conventionally, in semiconductor manufacturing devices such as plasma etching devices and plasma CVD (Chemical Vapor Deposition) devices, as shown in Patent Document 1, semiconductor wafers placed on substrate support members, etc. Between the substrate and the shower plate (gas distribution plate) for introducing and supplying the gas for plasma generation to the substrate, a high-frequency voltage is applied to form a plasma state, and a film is formed on the surface of the substrate or will be formed on the surface of the substrate. The thin film on the surface of the substrate is etched. This substrate support unit has a flow path in its thickness direction, and the temperature rise of the member W to be processed is suppressed by supplying cooling gas to the flow path.

When substrates are processed in a processing chamber of a semiconductor manufacturing device, arc discharge occurs from the upper side of the substrate support unit to the lower side, and the flow path may become a path of discharge. Therefore, in order not to make the flow path a path of discharge, Patent Document 2 proposes an electrostatic adsorption plate (substrate support assembly) in which a ceramic pin made of a porous honeycomb structure is mounted on the flow path.

[Prior Art Literature]

[Patent Document]

[Patent Document 1] Japanese Patent Laid-Open No. 2018-162205

[Patent Document 2] Japanese Patent Laid-Open No. 2019-165193

The air-permeable plug of the present disclosure has a dense ceramic honeycomb structure, and the dense ceramic honeycomb structure has a plurality of through holes in the axial direction.

The substrate supporting assembly disclosed in the present disclosure is formed by having an electrostatic adsorption member and a gas-permeable plug; wherein, the electrostatic adsorption member has: a base material having an adsorption surface on which the member to be processed is adsorbed and an opposite surface located on the adsorption surface. The plate-shaped ceramics on the opposite side of the side; the internal electrode is located in the base material; and the flow path is located along the thickness direction of the aforementioned base material; internal.

The shower plate of the present disclosure includes: a second base material, which is composed of plate-shaped ceramics, and the plate-shaped ceramics has a plurality of second flow paths through which the gas for plasma generation passes in the thickness direction; and the above-mentioned The air-permeable plug is installed inside the second flow path.

1: chamber

2: spray plate

2a: Diffusion

2b: Gas supply part

2c: The second channel

2d: breathable plug

3: Substrate support assembly support part

4: Installation Department

5: Insulation part

6: Support part

7: Heat conduction part

8: Electrostatic adsorption part

8a: Adsorption surface

8b: Substrate

8c: clamp electrode (internal electrode)

8d: flow path

9: Bonding layer

11: O-ring

13: breathable plug

14: breathable plug

15: High frequency power supply

16: Honeycomb structure

16a, 16b: through holes

16c: Peripheral area

16d: inner peripheral area

16e: Peripheral surface

16f: inner peripheral surface

17: Observe the object surface

18: Ridge

19: Concave

20: Plasma treatment device

(a) of FIG. 1 is a cross-sectional view showing part of a plasma processing apparatus equipped with a gas-permeable plug of the present disclosure, and (b) of FIG. 1 is an enlarged cross-sectional view of part A.

FIG. 2 is an enlarged cross-sectional view of a substrate support assembly disposed inside the plasma processing apparatus shown in FIG. 1 .

Fig. 3 is a sectional view showing an example of a section perpendicular to the axial direction of the air-permeable plug of the present disclosure.

4 is a cross-sectional view showing another example of a cross-section perpendicular to the axial direction of the air-permeable plug of the present disclosure.

5 is a cross-sectional view showing still another example of a cross-section perpendicular to the axial direction of the air-permeable plug of the present disclosure.

6(A) is a partially cutaway perspective view showing the through hole formed in the air-permeable plug of the present disclosure, and FIG. 6(B) is an enlarged explanatory view of the region X shown in FIG. 6(A).

An example of the air-permeable plug of the present disclosure will be described in detail below with reference to the drawings. However, in all the drawings in this specification, as long as there is no confusion, the same symbols are attached to the same parts, and the description thereof is omitted as appropriate.

FIG. 1 is a cross-sectional view showing part of a plasma treatment apparatus provided with a gas-permeable plug of the present disclosure. FIG. 2 is an enlarged cross-sectional view of a substrate support assembly disposed inside the plasma processing apparatus shown in FIG. 1 .

The plasma processing apparatus 20 shown in FIG. 1 is, for example, a plasma etching apparatus, which is equipped with a chamber 1 in which a processed member W such as a semiconductor wafer is disposed, and a shower plate 2 is disposed on the upper side of the chamber 1. The substrate support assembly 3 is disposed opposite to the lower side.

The shower plate 2 is a second base material made of plate-shaped ceramics, which is equipped with a diffusion part 2a and a gas supply part 2b; the aforementioned diffusion part 2a is used to diffuse the gas G used for plasma generation Between; the aforementioned gas supply unit 2b has a plurality of second flow paths 2c for supplying the gas G for plasma generation into the chamber 1 .

In addition, the plasma generation gas G discharged in a shower form from the gas supply part 2b through the second flow path 2c is formed by supplying high-frequency power (RF) from the high-frequency power source 15 to the substrate supporting unit 3. Plasma, and form the plasma space P.

Here, examples of the gas G for plasma generation include: fluorine-based gases such as SF ₆ , CF ₄ , CHF ₃ , ClF ₃ , NF ₃ , C ₄ F ₈ , and HF; Cl ₂ , HCl, BCl ₃ , CCl ₄ Chlorine gas.

The substrate support assembly 3 is an electrostatic adsorption plate provided with a mounting portion 4, an insulating portion 5, a supporting portion 6, a heat conduction portion 7, and an electrostatic adsorption portion 8. The electrostatic adsorption portion 8 is, for example, as shown in FIG. The bonding layer 9 made of silicone adhesive is bonded to the heat conduction portion 7 .

The electrostatic adsorption part 8 is provided with: a base material 8b, which is composed of a plate-shaped ceramic that adsorbs a processed member W such as a silicon wafer to the adsorption surface 8a by electrostatic adsorption force; electrode) 8c, which is located in the base material 8b; and flow path 8d, which is located along the thickness direction of the base material 8b. The clamp electrode (internal electrode) 8c is electrically connected to a high-frequency power source through a matching circuit for maintaining the plasma generated by the gas G for plasma generation in the chamber 1 .

Then, the coating film formed on the surface of the member W to be processed is subjected to etching treatment by ions or radicals contained in the plasma.

The O-ring 11 is installed around the bonding layer 9 to protect the bonding layer 9 . The insulating part 5 is made of plastic, for example, and is electrically insulated from the mounting part 4 . The flow path 8 d passes through the substrate support assembly 3 in the vertical direction, and is used to supply helium gas for cooling into the chamber 1 . The air-permeable pins 13 and 14 are attached to the flow path 8d. That is, the air-permeable plug 13 is provided in the flow path 8d in the electrostatic adsorption portion 8 , and the air-permeable plug 14 is provided in the flow path 8d in the insulating portion 5 .

Fig. 3 is a sectional view showing an example of a section perpendicular to the axial direction of the air-permeable plug of the present disclosure. 4 and 5 are cross-sectional views showing another example of a cross-section perpendicular to the axial direction of the air-permeable plug of the present disclosure.

As shown in Fig. 3 to Fig. 5, the air-permeable plug 13 is composed of a dense ceramic honeycomb structure 16 having a plurality of through holes 16a, 16b in the axial direction, and is a straight cylinder. The gas-permeable plug 14 is a cylinder with a shaft and a flange (not shown), the shaft is made of a honeycomb structure 16, and the flange is attached to one end of the shaft and has a diameter greater than Shaft. The flange part is also made of dense ceramics.

The so-called air-permeable plugs 13 and 14 in this disclosure refer to those that are arranged in the flow paths for circulating fluids such as gas and block the flow paths. Furthermore, the fluid can flow through the through-hole provided in a part of the air-permeable plug. The flow path provided with the air-permeable plug is, for example, a thinner flow path with an inner diameter of 1 mm to 10 mm, and the maximum internal dimension of the through hole provided with the air-permeable plug is, for example, about 5 μm to 20 μm.

The so-called honeycomb structure in this disclosure refers to a structure in which a plurality of (for example, more than 10) through-holes 16a, 16b are arranged along the axial direction. The arrangement of the plurality of through-holes is not particularly limited. For example, when arranged in a honeycomb shape, the strength of the air-permeable plug can be maintained high while the through-holes are densely arranged. The cross-section perpendicular to the axial direction of the through hole is not particularly limited, for example, it may be circular, triangular, quadrangular, or hexagonal. The through hole 16a among Fig. 3, Fig. 4 is the example that the cross section perpendicular to the axial direction of the honeycomb structure 16 is a circular example, and the through hole 16b in Fig. 5 is the cross section perpendicular to the axial direction of the honeycomb structure 16 is a hexagonal shape example. For example, the diameter of the through hole 16 a is 5 μm to 20 μm, and the length of the diagonal line of the through hole 16 b is 5 μm to 20 μm.

The gas-permeable plugs 13 and 14 can suppress secondary plasma generation in the flow path 8d. When the gas-permeable plugs 13, 14 are made of dense ceramic honeycomb structure 16, it is difficult to cause threshing, and even if the particles floating in the chamber 1 invade into the through holes 16a, 16b, the particles are not easily adsorbed on the inner periphery. surface 16f, and the mechanical strength becomes high.

Dense ceramics such as alumina (Al ₂ O ₃ ), yttrium aluminum composite oxide (at least any one of YAG, YAM, and YAP), aluminum nitride (AlN), silicon oxide (SiO ₂ ), silicon carbide (SiC) , silicon nitride (Si ₃ N ₄ ), yttrium oxide (Y ₂ O ₃ ) or yttrium zirconate as the main components. Yttrium zirconate has a composition formula represented by, for example, YZrOx (3≦x≦3.5), YZr ₂ O ₇ , Y ₂ ZrO ₅ , Y ₂ Zr ₂ O ₃ , Zr _0.92 Y _0.08 O _1.96 , and the like.

Dense ceramics refers to ceramics with a relative density of 96% or more, especially 97% or more and 99.8% or less. The relative density is the percentage of the apparent density of the honeycomb structure 16 relative to the theoretical density of the ceramic.

Also, regarding the theoretical density of ceramics, after pulverizing a part of the gas-permeable plugs 13 and 14, and dissolving the obtained powder in a solution such as hydrochloric acid, the density is measured by an ICP (Inductively Coupled Plasma) emission spectrometer (for example, , Shimadzu Corporation Co., Ltd. (ICPS-8100)) to obtain the content of metal components.

Each component constituting the honeycomb structure 16 was identified by an X-ray diffraction device using CuK α rays. If the identified component is Al ₂ O ₃ , use the value of Al content obtained by ICP (Inductively Coupled Plasma) emission spectrometer to convert to Al ₂ O ₃ . If the identified components are MgO and Na ₂ O, they can be converted to MgO and Na ₂ O in the same way. The apparent density of the honeycomb structure 16 can be obtained in accordance with JIS R 1634-1998.

In addition, when the main component constituting ceramics is alumina and the components other than the main component are magnesia, if the contents are respectively a mass % and b mass %, each of alumina and magnesia can be used. The value of theoretical density (aluminum oxide=3.99g/cm ³ , magnesium oxide=3.58g/cm ³ ) and the theoretical density (TD) of ceramics can be obtained by the following formula (1).

T.D=1/(0.01×(a/3.99+b/3.58))‧‧‧(1)

For example, when the content of the components constituting the ceramic is 99% by mass of alumina and 1% by mass of magnesium oxide, if calculated using formula (1), the theoretical density (TD) of the ceramic is 3.96g/cm ³ , which can be The relative density was obtained by dividing the apparent density of ceramics obtained according to JIS R 1634-1998 by this theoretical density (TD) of 3.96 g/cm ³ .

The honeycomb structure 16 shown in Fig. 4 and Fig. 5 has an outer peripheral region 16c and an inner peripheral region 16d, the aforementioned outer peripheral region 16c includes the outer peripheral surface 16e along the axial direction; the aforementioned inner peripheral region 16d excludes the outer periphery Side region 16c.

The outer peripheral region 16c including the outer peripheral surface 16e of the honeycomb structure 16 may have a smaller open porosity than the inner peripheral region 16d excluding the outer peripheral region 16c. With such a configuration, the length of the outline forming the air hole increases, and the length of the outer peripheral surface 16e from one end surface to the other end surface is substantially longer than that of the inner peripheral surface 16f, so the effect of suppressing arc discharge is high.

Conversely, the outer peripheral region 16c including the outer peripheral surface 16e of the honeycomb structure 16 may also have a larger open porosity than the inner peripheral region 16d excluding the outer peripheral region 16c. With such a configuration, when the air-permeable plugs 13, 14 are fixed in the flow path 8d of the substrate support unit 3 with an adhesive, a high anchoring effect can be obtained, so the reliability can be improved over a long period of time. .

The so-called outer peripheral area 16c, when the gas-permeable plug 14 is used, refers to the diameter of the honeycomb structure 16 on the cross section perpendicular to the axial direction, from the outer peripheral surface 16e to the radial direction, for example, within 4.5% of the diameter. area.

The respective open porosity of the outer peripheral side region 16c and the inner peripheral side region 16d can be obtained in accordance with JIS R 1634-1998. In any case, it is sufficient that the difference in open porosity is 0.8% or more.

The main component in this disclosure means the component which is the most among the total 100% by mass of the components constituting the dense ceramics.

The root mean square slope (RΔq) of the roughness curve of the inner peripheral surface 16f forming the through holes 16a, 16b can be smaller than the root mean square slope (RΔq) of the roughness curve of the outer peripheral surface 16e of the honeycomb structure 16 .

The root mean square slope (R△q) of the roughness curve refers to the root mean square of the local slope dZ/dx in the reference length 1 of the roughness curve measured in accordance with JIS B 0601:2001, and is based on the following defined by the formula.

When the value of the root mean square slope (RΔq) is large, the surface irregularities become steep, and when the value of the root mean square slope (RΔq) is small, the surface irregularities become gentle.

When the root-mean-square slope (RΔq) of the roughness curve of the inner peripheral surface 16f is smaller than the root-mean-square slope (RΔq) of the roughness curve of the outer peripheral surface 16e, the particles floating in the chamber 1 become more It is difficult to be adsorbed on the inner peripheral surface 16f. On the other hand, since the unevenness of the outer peripheral surface 16e becomes steep, when the honeycomb structure 16 is fixed to the electrostatic adsorption part 8, the insulating part 5, etc. with an adhesive, the adhesive follows the inclination of the uneven shape from Since the outer peripheral surface 16e penetrates deeply toward the inside, the honeycomb structure 16 can obtain high bonding strength and maintain high reliability over a long period of time.

The root mean square slope (RΔq) of the roughness curve of the outer peripheral surface 16e of the honeycomb structure 16 may also be smaller than the root mean square slope (RΔq) of the roughness curve of the inner peripheral surface 16f forming the through holes 16a, 16b .

In such a configuration, the local slope of the inner peripheral surface 16f from one end surface to the other end surface increases or inclines sharply, and its length becomes substantially longer than that of the outer peripheral surface 16e, thereby suppressing the effect of arc discharge. get taller. When the honeycomb structure 16 is installed on the electrostatic adsorption part 8, the insulating part 5, etc., even if the honeycomb structure 16 contacts the inner peripheral surface of these members and causes damage, there are few particles detached from the honeycomb structure 16, There are also few particles floating in the space in the chamber 1 . In addition, stress concentration generated on the outer peripheral surface 16e is also relaxed.

The root mean square slope (RΔq) can be measured using a shape analysis laser microscope (manufactured by Keyence Co., Ltd., VK-X1100 or its successor) in accordance with JIS B 0601:2001. As far as the measurement conditions are concerned, first, the illumination method is set to coaxial epi-illumination, the magnification is set to 240 times, the cutoff value λs is set to none, the cutoff value λc is set to 0.08mm, and the cutoff value λf is set to none , the correction of the terminal effect is set to have, and the measurement range from each of the outer peripheral surface 16e and the inner peripheral surface 16f as the measurement object is set to, for example, 1420 μm×1070 μm, and then along the length of the measurement range in each measurement range Pull the line set as the measurement object in the side direction, and measure the line roughness. The length set as a measurement object is 1320 micrometers, for example.

6(A) is a partially cutaway perspective view showing the through hole formed in the air-permeable plug of the present disclosure, and FIG. 6(B) is an enlarged explanatory view of the region X shown in FIG. 6(A). Fig. 6(A) and Fig. 6(B) show a state in which the axis C of the through hole is ground from the outer peripheral surface of the honeycomb structure in parallel with the axis C.

Starting from the inner peripheral surface 16f and the ridge line 18 of the observation object surface 17 obtained by grinding from the outer peripheral surface 16e toward the axis centers of the through holes 16a and 16b, the depth d is 10 μm or more and 20 μm The number of the following recesses 19 is 2 or less per ridge 18 length 1 mm, preferably 1 or less. The concave portion 19 is, for example, in the shape of a depression. The purpose of grinding toward the axis C from the outer peripheral surface 16e of the honeycomb structure 16 is to facilitate the measurement of the depth d of the concave portion 19 . The direction of the depth d is a direction toward the outer peripheral surface 16 e from the ridgeline 18 in the observation object surface 17 .

Here, the arithmetic mean roughness (Ra) of the observation object surface 17 is, for example, 0.01 μm or more and 0.1 μm or less, and the arithmetic mean roughness (Ra) can be obtained in accordance with JIS B 0601:2013. In addition, in order to obtain the observation object surface 17, WA (White Alundum) with an average particle diameter (D50) of 1 μm can be used as the abrasive material, and a polisher made of asphalt can be used as the grinding disc.

In addition, when it is a honeycomb structure 16 with an outer diameter of 3mm or more, it can be cut from the outer peripheral surface 16e of the honeycomb structure 16 toward the axis C, leaving a grinding margin of 0.1mm to 0.2mm before cutting. grind.

」(Hasamu Monosashi)之免費軟體來測定凹部的深度d，並計算出深度d為10μm以上20μm以下之凹部19的個數即可。 Then, the image of the observation object surface 17 (for example, 2.3 mm in width and 1.7 mm in length) captured by a scanning electron microscope is used as the object, using, for example, the image named "

" (Hasamu Monosashi) free software to measure the depth d of the concave portion and calculate the number of concave portions 19 whose depth d is not less than 10 μm and not more than 20 μm.

Here, the reason why the depth of the concave portion 19 is set to be 10 μm or more is because the depth of 10 μm is the minimum value, that is, the threshold value, at which the threshing and floating particles have a significant adverse effect on the plasma space P.

In this way, since the recessed part 19 hardly exists on the inner peripheral surface 16f, the generation|occurrence|production of the threshing (chipping) starting from the inner peripheral surface 16f will be in the state suppressed. Therefore, even if a fluid such as gas passes through the through-holes 16a and 16b, it is possible to reduce the possibility that the detached particles become new particles and float in the plasma space P.

The recessed part 19 referred to here means, in other words, a depression opening in the inner peripheral surface 16f.

」之免費軟體來測定稜線18的真直度。只需將貫通孔16a、16b的軸向對著圖像的縱向，使圖像包含夾住內周面16f之左右的稜線18中之至少任一者，並將幾何正確的直線之長度設為1.4mm即可。 On the observation object surface 17, the straightness of the ridgeline 18 may be, for example, 20 μm or less. The so-called true straightness refers to the deviation of the ridge line 18 from a geometrically correct straight line. As far as straightness is concerned, the image of the observation object surface 17 (for example, horizontal 1.2 mm, vertical 1.4 mm) taken by an optical microscope can be used as the object, and for example, use the name "

" free software to measure the true straightness of the ridge line 18. It is only necessary to align the axial directions of the through holes 16a and 16b with the longitudinal direction of the image so that the image includes at least any one of the left and right ridges 18 sandwiching the inner peripheral surface 16f, and set the length of the geometrically correct straight line to be 1.4mm is enough.

If the straightness of the ridge line 18 is 20 μm or less, there will be almost no large depressed recesses 19 on the inner peripheral surface 16f, so even if the flow of the gas is turbulent, new particles floating on the electric field can be reduced. Doubts in pulp space P.

The dense ceramics may contain alumina as a main component and contain sodium at a content of 20 mass ppm or less. Since sodium is an element that increases dielectric loss, when the content of sodium is 20 mass ppm or less, the dielectric loss can be reduced and high electromagnetic wave penetration can be obtained.

The through-holes 16a, 16b may be bent and penetrated from one end surface to the other end surface. In this case, compared with the case where the straightness of the through-holes 16a, 16b is high, the substantial flow path in the axial direction of the through-holes 16a, 16b becomes longer, so it becomes easier to suppress the occurrence of arc discharge.

The cylindricity of the through-holes 16a and 16b may be, for example, not less than 0.05 mm and not more than 0.2 mm. When the cylindricity of the through-holes 16a, 16b is greater than 0.05mm, the distance through which the current flows can be extended, so electrons are less likely to be accelerated, and less likely to cause arc discharge. When the cylindricity of the through-holes 16a, 16b is 0.2mm or less, the increase in the air permeability resistance of the cooling gas can be suppressed, and the cooling efficiency can be maintained, and even if it is repeatedly exposed to temperature rise and fall, it is difficult to generate strain, so it can cover a long period of time use.

The dense ceramics may contain alumina as the main component and contain magnesium aluminate, and subtract the equivalent value of the magnesium aluminate crystal particles from the average distance between the centers of gravity of the magnesium aluminate crystal particles adjacent to the outer peripheral side region 16c. The value obtained after the average value of the circle diameter is obtained by subtracting the average value of the equivalent circle diameter of the crystal particles of magnesium aluminate from the average distance between the centers of gravity of the crystal particles of magnesium aluminate adjacent to the inner peripheral side region 16d The resulting value is greater.

In such a configuration, since the linear expansion rate of magnesium aluminate is greater than that of alumina, in the outer peripheral side region 16c, during the cooling process of sintering, the crystal particles of magnesium aluminate are located more on the outer periphery than the crystal particles of alumina. The surface moves in a raised manner, so even if heat treatment is performed to place the honeycomb structure 16 on the powder floor after sintering to reduce warpage or to remove strain, it can be suppressed from becoming the outer periphery of the placed surface of the honeycomb structure 16. The noodles are fused with the flour.

On the other hand, in the inner peripheral side region 16d, the intervals between crystal particles of magnesium aluminate are small, that is, they are in a dispersed state, and even if a tensile load is applied at a high temperature, crack-like holes are not easily generated. (cavity), so it will improve the high temperature ductility.

The distance between crystal particles of magnesium aluminate can be obtained by the following method. Observe the cross-sections of the inner peripheral region 16d and the outer peripheral region 16c of the dense ceramics at a magnification of 100 times, select an average range, and use a scanning electron microscope, for example, to make the area 1.044mm ² (the horizontal length is 1.18 mm). mm, and the longitudinal length is 0.885mm) to obtain a reflected electron image.

With this reflected electron image as the object, image analysis software "A IMAGE KUN (ver 2.52)" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd., hereinafter described as image analysis software "A IMAGE KUN" When, it means Asahi Kasei Engineering shares Co., Ltd.'s image analysis software), and the distance between the centers of gravity of the crystal particles of magnesium aluminate can be calculated by the method of the distance between the centers of gravity of the dispersion measurement.

As for the setting conditions of this method, for example, it is only necessary to set the threshold value of the index indicating the brightness of the image to 180, the brightness to bright, the small pattern removal area to 10 μm ² , and the noise removal filter to be absent. In addition, although the threshold is set to 180 in the above measurement, the threshold can be adjusted in response to the brightness of the observed image. After the brightness has been set to bright, the method of binarization is set to manual, and the small pattern removal area is set to In the case of 10 μm ² and the noise removal filter is set to none, it is only necessary to adjust the threshold so that the mark displayed on the observed image becomes consistent with the shape of the crystal particles of magnesium aluminate.

Also, when it is difficult to distinguish the crystal particles of magnesium aluminate compared to other parts, it is only necessary to obtain the distance between the centers of gravity of the crystal particles after blackening the crystal particles. In this case, for example, it is only necessary to set the threshold value to 85, the brightness to dark, the small pattern removal area to 10 μm ² , and the noise removal filter to none.

The equivalent circle diameter of the crystal particles of magnesium aluminate can be obtained by using the image analysis software "A IMAGE KUN" and the method of particle analysis by using the above-mentioned reflected electron image as the object. The setting conditions of this method need only be set to be the same as those used in the distance method between centers of gravity for dispersion measurement.

Here, magnesium aluminate is identified using an X-ray diffraction device, and whether the crystal particles observed in the above reflected electron image are magnesium aluminate is identified using an electron probe microanalyzer (EPMA, Electron Probe Micro Analyzer), if aluminum and magnesium are detected, it can be considered that the crystal particles are composed of magnesium aluminate.

Dense ceramics can also contain silicon carbide as the main component and metal silicon. In this case, silicon carbide is, for example, 70% by mass or more and 92% by mass or less, and metal silicon is 8% by mass or more and 30% by mass or less. The mechanical properties of Young's modulus (dynamic modulus of elasticity) and 3-point bending strength of silicon carbide are better than those of metal silicon. Therefore, when the content of silicon carbide is more than 70% by mass, the mechanical properties of dense ceramics will be improved. On the other hand, the thermal conductivity of metallic silicon is higher than that of silicon carbide. Therefore, when the content of silicon carbide is less than 92% by mass, the thermal conductivity of the dense ceramic will be improved. Therefore, if the content of silicon carbide is not less than 70% by mass and not more than 92% by mass, both mechanical properties and thermal conductivity can be achieved.

The components contained in dense ceramics can be identified by X-ray diffraction equipment, and the respective contents of silicon carbide and silicon can be obtained by the Rietveld method.

The difference between the average value of the center-of-gravity distance of metal silicon and the average value of the equivalent circle diameter of metal silicon is not limited, for example, it may be 8 μm or more and 20 μm or less. When the difference is 8 μm or more, the distribution density of silicon carbide becomes high. Therefore, the rigidity of dense ceramics is improved, and the bias of rigidity is also reduced. On the other hand, when the difference is 20 μm or less, the thermal conductivity of dense ceramics is improved, and the unevenness of thermal conductivity is also reduced.

The distance between centers of gravity of silicon metal in dense ceramics can be obtained by the following method.

First, cut out a part of the dense ceramics, and select an average range from the mirror surface obtained by grinding the cross section using diamond abrasive grains, and use a scanning electron microscope to determine the area of each to be 0.191mm ² (horizontal length Observation images were obtained by shooting in the range of 351 μm and 545 μm in the longitudinal direction.

Using this observation image as a target, use the image analysis software "A IMAGE KUN (ver 2.52)" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd., described in the following description) When loaded as the image analysis software "A IMAGE KUN", it refers to the image analysis software manufactured by Asahi Kasei Engineering Co., Ltd.), and the distance between the centers of gravity of silicon is obtained by the method of the distance between the centers of gravity of the dispersion measurement .

As for the setting conditions of this method, the threshold value of the index indicating the brightness of the image is set to 190 to 195, the brightness is set to bright, the small pattern removal area is set to 1 μm ² , and the noise removal filter is set to on.

The circle-equivalent diameter of silicon is obtained by using the above-mentioned observation image as an object and by means of particle analysis.

The setting conditions of this method are the same as those used in the method of distance between centers of gravity. Moreover, at least the outer peripheral surface of the honeycomb structure 16 may be equipped with the 1st electroconductive part comprised from the layer or film which has electroconductivity.

Recently, the high-frequency (RF) power applied to the electrostatic adsorption part 8 has gradually become higher. When this high-frequency power becomes high, abnormal discharge such as arc discharge may occur in or near the flow path 8d. That is, when RF power is applied to the substrate supporting unit 3 , a potential difference is generated between the member W to be processed and the inner surface of the electrostatic adsorption unit 8 due to the electrostatic capacity of the electrostatic adsorption unit 8 . Due to the generation of this potential difference, a potential difference of RF potential is generated inside the flow path 8d, and when the potential difference exceeds the critical value for generating discharge, abnormal discharge will occur.

When the first conductive portion is provided on the outer peripheral surface, it is easy to remove static electricity along the outer peripheral surface, so it is easy to suppress abnormal discharge in the flow path 8d.

At least one end surface of the honeycomb structure 16 may be provided with a second conductive portion made of a conductive layer or film. When the second conductive portion is provided on the end face, since static electricity is easily removed along the end face provided with the second conductive portion, abnormal discharge in the flow path 8d can be further suppressed.

The inner peripheral surface of the honeycomb structure 16 may include a third conductive portion made of a conductive layer or film. When the third conductive portion is provided on the inner peripheral surface, since static electricity is easily removed along the inner peripheral surface, abnormal discharge in the flow path 8d can be further suppressed.

Here, having conductivity means that the surface resistance value is 10 ⁴ Ω or less. The surface resistance value may be obtained by using a two-probe resistance meter (prostat, PRS-802) and setting the applied voltage to 100V.

The first conductive portion, the second conductive portion, and the third conductive portion are made of, for example, graphite, graphene, carbon nanotubes, fullerene, amorphous carbon, and DLC (diamond-like carbon, Diamond- At least any one of Like Carbon).

Furthermore, after immersion in hydrochloric acid with a concentration of 35% by mass, and after 72 hours from the start of immersion, the mass change C per unit area represented by the following formula (2) can be 0.3 g/cm ² the following.

C=(W ₀ -W ₁ )/A‧‧‧(2)

(W ₀ : mass (g) of the test piece before immersion, W ₁ : mass (g) of the test piece 72 hours after immersion, A: surface area (cm ² ) of the test piece before immersion)

When the mass change C per unit area is 0.3g/cm ^or less, the particle systems that respectively constitute the first conductive part, the second conductive part and the third conductive part are not easy to peel off, so it can cover a long period of immersion in hydrochloric acid, and improve Dirt removal effect.

As mentioned above, the substrate supporting assembly 3 of the present disclosure is provided with: an electrostatic adsorption member 8 and the air-permeable plugs 13 and 14 of the present disclosure; wherein, the aforementioned electrostatic adsorption member 8 has a base material 8b, which has an adsorption It is composed of plate-shaped ceramics with the adsorption surface 8a of the member W to be processed; the interior The electrode 10 is located in the base material 8b, and the flow channel 8d is located along the thickness direction of the base material 8b; the aforementioned gas-permeable plugs 13, 14 of the present disclosure are mounted inside the flow channel 8d.

The air-permeable pins 13 and 14 are not easy to cause threshing, and even if the particles floating in the chamber 1 invade into the through holes 16a and 16b, the particles are not easy to be adsorbed on the inner peripheral surface 16f, and because of the high mechanical strength, it can cover a long period of time use.

In addition, the substrate 8b and the air-permeable plugs 13 and 14 are made of ceramics mainly composed of alumina, and the purity (content) of the alumina of the air-permeable plugs 13 and 14 is comparable to that of the alumina of the substrate 8b. (content) is higher. When the purity of alumina becomes higher, the corrosion resistance to plasma will be improved, and the withstand voltage will be higher, so the generation of arc discharge can be suppressed.

In particular, the purity of the alumina in the air-permeable plugs 13 and 14 may be 99.6% by mass or more. In addition, the content of calcium may be 0.01% by mass or less. When the calcium content is less than 0.01% by mass, even if the gas-permeable plugs 13 and 14 are cleaned with citric acid, there is less calcium with low corrosion resistance to citric acid, which can reduce the calcium source from becoming particles and contaminating the chamber. Doubts in Room 1.

In addition, as shown in (b) of FIG. 1 , the shower plate 2 may be equipped with the air-permeable plug 2d of the present disclosure inside the second flow path 2c. With such a configuration, it is possible to suppress the backflow of plasma and particles from the plasma space P toward the shower plate 2, or suppress the abnormal discharge generated in the second flow path 2c, thereby preventing the occurrence of abnormal discharge that may be caused. resulting in a fire.

Next, an example of the method of manufacturing the air-permeable plug of the present disclosure will be described.

When it is desired to obtain a gas-permeable plug composed of dense ceramics mainly composed of alumina, firstly, the powder of alumina with a purity of 99.6 mass% or more and an average particle size (D50) of 1 μm to 3 μm is bonded. Binder, lubricant and solvent are mixed.

The powder of alumina may contain magnesia or sodium. The content of magnesium oxide in 100% by mass of alumina powder is, for example, 0.1% by mass or more and 0.3% by mass or less. The content of sodium in 100% by mass of alumina powder is, for example, 20 mass ppm or less. Here, the average particle diameter (D50) can be calculated|required by the laser diffraction particle size distribution measurement method.

When it is desired to obtain a gas-permeable plug made of dense ceramics with silicon carbide as the main component, firstly, coarse-grained powder and granular powder are prepared as silicon carbide powder, and together with ion-exchanged water and dispersant, pass through a ball mill Or bead mill for crushing and mixing for 40 to 60 hours to form a slurry. Here, the respective particle diameter ranges of the pulverized and mixed fine-grained powder and the coarse-grained powder are not less than 0.4 μm and not more than 4 μm, and not more than 11 μm and not more than 34 μm.

Next, to the obtained slurry, a sintering aid consisting of boron carbide powder, amorphous carbon powder, or phenolic resin, and a binder are added and mixed.

The mass ratio of the fine-grained powder to the coarse-grained powder is, for example, 6 mass % to 15 mass % for the fine-grained powder, and 85 mass % to 94 mass % for the coarse-grained powder.

The binder is, for example, methyl cellulose (MC), carboxymethyl cellulose (CMC), hydroxypropyl cellulose (HPC), polyvinyl alcohol (PVA), polyvinyl butyral (PVB) and the like. With respect to 100 parts by mass of alumina or silicon carbide powder, the total amount of the binder may be 2 parts by mass or more and 8 parts by mass or less in terms of solid content. When the solid content of the binder is within this range, the fluidity of the extrusion molding and the shape retention of the molded body can be maintained high.

Lubricants are waxes, glycerin, stearic acid and the like. With respect to 100 parts by mass of alumina or silicon carbide powder, the total amount of the lubricant may be 1 to 8 parts by mass in terms of solid content.

In addition, the solvent is, for example, water, and especially ion-exchanged water is preferable since the amount of impurities is small. The solvent is used so that the viscosity of the clay in the kneading step is not less than 15000Pa‧s and not more than 22000Pa‧s In this way, it is set to be, for example, 10 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of alumina powder.

After mixing alumina or silicon carbide powder, binder, lubricant and solvent at the above-mentioned blending ratio, use a universal mixer or a 3-roll kneading machine to knead to obtain a viscosity of, for example, 15000Pa‧s or more to 22000Pa‧ Embryo soil below s. Viscosity can be measured by a flow characteristic evaluation method using a constant-load extrusion rheometer (Shimadzu Flow Tester CFT-500C, manufactured by Shimadzu Corporation).

The clay was molded using an extrusion molding machine equipped with a die for forming through holes for forming a molded body to obtain a honeycomb shaped molded body having a plurality of through holes in the axial direction.

Here, since the root-mean-square slope (RΔq) of the roughness curve of the inner peripheral surface of the through-hole forming the honeycomb structure and the outer peripheral surface of the honeycomb structure is affected by the transfer surface of the stamper, it is appropriate to Just adjust the transfer surface of the stamper.

After the molded body is cut to a length of, for example, 20 mm to 80 mm, it is dried to remove moisture in the molded body. The drying temperature is, for example, 40 to 70°C. When the main component of the dried molded body is alumina, the molded body is fired in the atmosphere at a temperature of 1550°C to 1650°C for 0.5 hours to 5 hours, thereby obtaining the air permeability of the present disclosure. sex plug.

When the main component of the molded body after drying is silicon carbide, degrease by setting the temperature at 450°C to 650°C and holding time at 2 hours to 10 hours in a nitrogen atmosphere to obtain a degreased body . Next, the degreased body is fired at a temperature of 1800° C. to 2200° C. for 0.5 hours to 5 hours in a depressurized environment of an inert gas such as argon, thereby obtaining the air-permeable plug of the present disclosure.

Another example of the manufacturing method of the air-permeable plug of the present disclosure will be described.

The manufacturing method of the air-permeable plug comprises the following steps (a) to (e).

Step (a): The step of storing the powder, wax, dispersant, and plasticizer mainly composed of alumina whose particle size is 6.5 μm or less in the cumulative distribution curve of the cumulative 95% by volume, and stirring to obtain a slurry .

Step (b): the step of preheating the slurry.

Step (c): a step of degassing the preheated slurry.

Step (d): A step of injecting the slurry into a molding die surrounded by heating means on the outer peripheral side to obtain a molded body.

Step (e): the step of firing into a shape.

Step (a) is a step of storing raw materials in a container and stirring them to obtain a slurry. The raw materials are powder, wax, dispersant and plasticizer mainly composed of alumina.

For powders mainly composed of alumina, the particle size of the cumulative 95% by volume of the cumulative distribution curve is 6.5 μm or less. By using such a powder, for example, a dense ceramic having a relative density of 96% or more can be obtained, and the formation of the recesses 19 on the inner peripheral surface 16f is reduced. In particular, the recesses 19 can be further reduced by reducing the average particle size of the powder used. The purity of the powder of the main component is not limited, and powder having a purity of, for example, 99.5% by mass or higher can be used.

The so-called cumulative distribution curve means a curve showing the cumulative distribution of particle diameters in a two-dimensional graph where the horizontal axis represents the particle diameter and the vertical axis represents the cumulative percentage of the particle diameter. The cumulative distribution curve can be obtained by the laser diffraction scattering method using, for example, a particle size distribution measuring device (MT3300 or its successor) manufactured by MicrotracBEL.

With respect to 100 parts by mass of the above powder, the amount of wax is 13 parts by mass to 14 parts by mass, the dispersant is 0.4 parts by mass to 0.5 parts by mass, and the plasticizer is 1.4 parts by mass to 1.5 parts by mass. Use the ratio of parts by mass or less. As wax, paraffin wax (paraffin wax), beeswax etc. are mentioned, for example. As a dispersant, a higher fatty acid, a higher fatty acid ester, etc. are mentioned, for example. As a plasticizer, a higher fatty acid, a phthalate, etc. are mentioned, for example.

The above-mentioned powder, wax, dispersant, and plasticizer are stored in a container heated to, for example, 90°C or higher and 140°C or lower. At this time, the wax, dispersant and plasticizer become liquid. The container is made of resin, for example. The container was attached to a mixer, and the container was rotated on its own axis for 3 minutes (rotation-revolution kneading process), thereby stirring the above-mentioned powder, wax, dispersant, and plasticizer to obtain a slurry.

In step (b), the slurry obtained in step (a) is preheated. By preheating, the fluidity of the slurry will become higher, and the effect obtained in the step (c) can be further improved. Preheating is performed at a temperature of, for example, 120°C to 180°C.

In step (c), the slurry preheated in step (b) is subjected to degassing treatment. By performing defoaming treatment, the air bubbles contained in the slurry can be reduced, so dense ceramics with higher relative density can be obtained. For defoaming treatment, for example, a syringe is filled with the obtained slurry, and defoaming is carried out while the syringe is rotated on its own axis for 1 minute using a defoaming fixture.

In the step (d), the slurry after the defoaming treatment in the step (c) is injected into a molding mold to obtain a molded body. The molding die is a molding die with heating means around the outer peripheral side. In this way, the honeycomb structure shown in FIGS. 3 to 5 can be obtained by using a molding die with heating means surrounding its outer periphery. Heating means is not limited, For example, a heater etc. are mentioned. By means of heating, for example, it is possible to heat so that the temperature difference from the slurry temperature at the time of pouring into the molding die is within 50°C. The shape of the formed body is not limited, and may have a cylindrical shape as shown in FIGS. 3 to 5 , or may have other shapes such as a prismatic shape.

In step (e), the molded body obtained in step (c) is fired. The firing may be carried out, for example, under an air atmosphere at 1400° C. to 1700° C. for 1 hour to 3 hours. In this manner, the air-permeable plug of the present disclosure, which is a dense ceramic honeycomb structure having a plurality of through holes in the axial direction, can be obtained. In the gas-permeable pins 13 and 14 obtained in this way, the inner peripheral surface 16f forming the through-holes 16a and 16b and the axis C from the outer peripheral surface 16e of the honeycomb structure toward the through-holes 16a and 16b are ground. The ridgeline 18 of the observation object surface 17 is the starting point, and the number of recesses 19 having a depth d of 10 μm to 20 μm is 1 mm or less per ridgeline 18 .

In order to obtain a gas-permeable plug with at least the outer peripheral surface of the honeycomb structure having the first conductive part, it is only necessary to coat or spray the outer peripheral surface of the dried molded body containing graphite, graphene, carbon nanotubes, fullerenes, After the 2-propanol (IPA) solution of carbon such as crystalline carbon, the above-mentioned firing can be carried out.

In order to obtain a gas-permeable plug with a second conductive part on at least any end face of the honeycomb structure, it is only necessary to apply or spray the above-mentioned 2-propanol (IPA) solution on the end face of the dried molded body, and then perform the above-mentioned firing. Can.

In order to obtain a gas-permeable plug with a third conductive part on the inner peripheral surface of the honeycomb structure, it is only necessary to apply or spray the above-mentioned 2-propanol (IPA) solution on the inner peripheral surface of the dried molded body, and then perform the above-mentioned firing. Can.

When at least any one of the first conductive part, the second conductive part, and the third conductive part is formed by DLC, the sintered body obtained by the above-mentioned firing can be formed by using the plasma ion implantation method. After the film formed by DLC, the temperature is set at 200°C to 1000°C, and heat treatment is performed for at least 1 hour.

The gas-permeable plug of the present disclosure obtained by the above-mentioned manufacturing method is not easy to cause threshing, and even if the particles floating in the chamber invade into the through holes 16a, 16b, the particles are not easily adsorbed on the inner peripheral surface 16f, and the mechanical strength is high. Therefore, it can cover long-term use.

2b: Gas supply part

2c: The second channel

2d: breathable plug

Claims (20)

A gas-permeable plug is provided with a dense ceramic honeycomb structure, and the dense ceramic honeycomb structure has a plurality of through holes in the axial direction, wherein the mean square of the roughness curve of the inner peripheral surface of the aforementioned through holes is formed The root slope (RΔq) is smaller than the root mean square slope (RΔq) of the roughness curve of the outer peripheral surface of the aforementioned honeycomb structure. The air-permeable plug according to claim 1, wherein the open porosity of the outer peripheral region including the outer peripheral surface of the honeycomb structure is smaller than the open porosity of the inner peripheral region excluding the outer peripheral region. The air-permeable plug according to claim 1, wherein the open porosity of the outer peripheral region including the outer peripheral surface of the honeycomb structure is greater than the open porosity of the inner peripheral region excluding the outer peripheral region. The air-permeable plug according to claim 1 or 2, wherein the inner peripheral surface forming the through-hole and the ridge line of the observation object surface obtained by grinding from the outer peripheral surface of the honeycomb structure toward the axis of the through-hole As a starting point, the number of recesses with a depth of 10 μm to 20 μm is 2 or less per ridge length of 1 mm. The air-permeable plug according to claim 4, wherein the straightness of the ridgeline on the observation object surface is 20 μm or less. The air-permeable plug according to claim 1 or 2, wherein the dense ceramics are mainly composed of alumina and contain sodium, and the sodium content is 20 mass ppm or less. The gas-permeable plug according to Claim 6, wherein the dense ceramics are mainly composed of alumina and contain magnesium aluminate; subtract the average distance between the centers of gravity of adjacent magnesium aluminate crystal particles In terms of the value after the average value of the equivalent circle diameter of the crystal particles of magnesium aluminate, including the aforementioned The outer peripheral area of the outer peripheral surface of the honeycomb structure is larger than the inner peripheral area of the inner peripheral surface including the aforementioned through holes. The air-permeable plug according to claim 1 or 2, wherein the aforementioned dense ceramic is mainly composed of silicon carbide and contains metallic silicon. The air-permeable plug according to claim 8, wherein the difference between the average value of the distance between the centers of gravity of the metal silicon and the average value of the equivalent circle diameter of the metal silicon is not less than 8 μm and not more than 20 μm. The air-permeable plug according to claim 1 or 2, wherein the honeycomb structure has a first conductive portion made of a conductive layer or film at least on the outer peripheral surface. The air-permeable plug according to claim 1 or 2, wherein at least any end surface of the honeycomb structure is equipped with a second conductive portion made of a conductive layer or film. The air-permeable plug according to Claim 10, wherein the inner peripheral surface of the honeycomb structure is provided with a third conductive portion made of a conductive layer or film. The air-permeable plug according to Claim 6, wherein the mass change C per unit area represented by the following formula (2) after 72 hours of immersion in hydrochloric acid with a concentration of 35% by mass is 0.3 g C = ₍ W _{0 -W} ¹ ₎ /A Mass (g), A; surface area (cm ² ) of the test piece before immersion. A gas-permeable plug is provided with a dense ceramic honeycomb structure, and the dense ceramic honeycomb structure has a plurality of through holes in the axial direction, wherein the aforementioned dense ceramic is mainly composed of silicon carbide and contains metal Silicon. A gas-permeable plug is provided with a dense ceramic honeycomb structure, and the dense ceramic honeycomb structure has a plurality of through holes in the axial direction. The first conductive part composed of layers or films. A gas-permeable plug is provided with a dense ceramic honeycomb structure, and the dense ceramic honeycomb structure has a plurality of through holes in the axial direction, wherein at least any end surface of the aforementioned honeycomb structure is equipped with a The second conductive part composed of layers or films. A substrate support assembly comprising an electrostatic adsorption member and the gas-permeable plug described in any one of Claims 1 to 16; wherein, the electrostatic adsorption member includes: a base material having a member adsorbed thereon The adsorption surface and the plate-shaped ceramics on the opposite side of the adsorption surface; the internal electrode is located in the substrate; and the flow path is located along the thickness direction of the substrate; the above-mentioned air-permeable The sex pin is installed in the inside of the aforementioned flow path. The substrate support assembly according to claim 17, wherein the base material and the gas-permeable plug are made of ceramics mainly composed of alumina, and the purity of the alumina is higher than that of the gas-permeable plug. A substrate support assembly is provided with an electrostatic adsorption member and a gas-permeable plug; wherein the electrostatic adsorption member has: a base material, which has an adsorption surface on which the member to be processed is adsorbed and a surface located on the opposite side of the adsorption surface. The opposite surface is made of plate-shaped ceramics; the internal electrode is located in the base material; and the flow path is located along the thickness direction of the aforementioned base material; the gas-permeable plug is installed inside the aforementioned flow path, And it has a dense ceramic honeycomb structure, the dense ceramic honeycomb structure has a plurality of through holes in the axial direction; and the aforementioned base material and the aforementioned air-permeable plug are made of ceramics mainly composed of alumina, The purity of alumina is higher than that of the aforementioned base material because of the aforementioned air-permeable plug. A shower plate comprising: a second base material composed of a plate-shaped ceramic having a plurality of second flow paths through which a gas for plasma generation passes in a thickness direction; and claims The air-permeable plug according to any one of 1 to 16 is mounted inside the second flow path.

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