TW202202472A - 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

Breathable Latches, Substrate Support Assemblies, and Shower Plates

The present disclosure relates to an air-permeable plug and a substrate support assembly provided with the air-permeable plug.

Conventionally, in a semiconductor manufacturing apparatus such as a plasma etching apparatus and a plasma CVD (Chemical Vapor Deposition) apparatus, as shown in Patent Document 1, a semiconductor wafer or the like mounted on a substrate support member is used. A high-frequency voltage is applied between the substrate and a shower plate (gas distribution plate) for introducing and supplying the plasma-generating gas to the substrate to bring about 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 assembly includes a flow path in the thickness direction thereof, and the temperature rise of the member to be processed W is suppressed by supplying the cooling gas to the flow path.

When a substrate is processed in a processing chamber of a semiconductor manufacturing apparatus, an arc discharge occurs from the upper side of the substrate support member to the lower side, and the flow path may become a path of the discharge. Therefore, in order to prevent the flow path from becoming a path of discharge, Patent Document 2 proposes an electrostatic suction pad (substrate support member) in which a ceramic plug having a porous honeycomb structure is attached to the flow path.

[Prior Art Literature]

[Patent Literature]

[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 includes a honeycomb structure of dense ceramics, and the honeycomb structure of dense ceramics has a plurality of through holes in the axial direction.

The substrate support assembly of the present disclosure is provided with an electrostatic adsorption member and an air-permeable plug; wherein, the electrostatic adsorption member includes a base material having an adsorption surface on which the member to be processed is adsorbed, and an opposite side located on the adsorption surface. The inner electrode is located in the base material; and the flow path is located along the thickness direction of the base material; the gas-permeable plug is attached to the flow path. internal.

The shower plate of the present disclosure includes: a second base material made of a plate-shaped ceramic having a plurality of second flow paths in the thickness direction through which the gas for plasma generation passes; and the above-mentioned An air-permeable plug is attached to the inside of the second flow path.

1: Chamber

2: spray plate

2a: Diffusion part

2b: Gas supply section

2c: 2nd flow path

2d: breathable latch

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 latch

14: Breathable latch

15: High frequency power supply

16: Honeycomb Structure

16a, 16b: Through hole

16c: Peripheral side area

16d: Inner peripheral area

16e: Outer peripheral surface

16f: Inner peripheral surface

17: Observe the object face

18: Ridgeline

19: Recess

20: Plasma processing device

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

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

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

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

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

FIG. 1 is a cross-sectional view showing a portion of a plasma processing apparatus provided with the gas-permeable plug of the present disclosure. FIG. 2 is an enlarged cross-sectional view of a substrate support member 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 provided with a chamber 1 inside which a processed member W such as a semiconductor wafer is arranged, and a shower plate 2 is arranged on the upper side of the chamber 1 , The substrate support assembly 3 is arranged opposite to the lower side.

The shower plate 2 is a second base material made of plate-shaped ceramics, and includes a diffusion part 2a and a gas supply part 2b; the diffusion part 2a is used to diffuse the inner space of the gas G for plasma generation. The above-mentioned gas supply part 2b has a plurality of second flow paths 2c for supplying the gas G for plasma generation into the chamber 1 .

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

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 , and CCl _{4 .} and other chlorine-based gases.

The substrate support assembly 3 is an electrostatic attraction plate comprising a mounting part 4, an insulating part 5, a support part 6, a heat conduction part 7 and an electrostatic attraction part 8. The electrostatic attraction part 8 is, for example, as shown in FIG. The bonding layer 9 formed of the silicon-oxygen adhesive is bonded to the thermally conductive portion 7 .

The electrostatic attraction part 8 has a base material 8b made of a plate-shaped ceramic that attracts the processed member W such as a silicon wafer to the attraction surface 8a by electrostatic attraction force; a clamp electrode (inside Electrodes) 8c, which are located in the base material 8b; and flow paths 8d, which are 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 plasma-generating gas G in the chamber 1 .

Then, the coating film formed on the surface of the member to be processed W 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 portion 5 is made of, for example, plastic, and is electrically insulated from the mounting portion 4 . The flow path 8d penetrates the vertical direction of the substrate support assembly 3 and is used for supplying the 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 part 8 , and the air-permeable plug 14 is provided in the flow path 8d in the insulating part 5 .

3 is a cross-sectional view showing an example of a cross-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 FIGS. 3 to 5 , the air-permeable plug 13 is formed of a dense ceramic honeycomb structure 16 having a plurality of through holes 16a and 16b in the axial direction, and is a straight cylindrical body. The breathable plug 14 is a cylinder with a shaft portion and a flange portion (not shown), the shaft portion is composed of a honeycomb structure 16, and the flange portion is connected to one end of the shaft portion and has a diameter larger than Axial. The flange portion is also made of dense ceramics.

The air-permeable plugs 13 and 14 in the present disclosure are provided in a flow path for flowing a fluid such as gas and block the flow path. Furthermore, the fluid can be circulated through a through hole provided in a part of the air-permeable plug. The flow path provided with the air-permeable plug is, for example, a relatively thin flow path with an inner diameter of 1 mm to 10 mm, and the maximum inner dimension of the through hole provided with the air-permeable plug is, for example, a thin one of about 5 μm to 20 μm.

The honeycomb structure in the present disclosure means a structure in which a plurality of (for example, 10 or more) through holes 16a and 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 through holes can be densely arranged while maintaining the strength of the air-permeable plug at a high level. The cross section perpendicular to the axial direction of the through hole is not particularly limited, and for example, it is a circular shape, a triangular shape, a quadrangular shape, and a hexagonal shape. The through hole 16a in FIGS. 3 and 4 is an example in which the cross section perpendicular to the axial direction of the honeycomb structure 16 is circular, and the through hole 16b in FIG. example. For example, the diameter of the through hole 16a is 5 μm to 20 μm, and the length of the diagonal line of the through hole 16b is 5 μm to 20 μm.

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

Dense ceramics are, for example, aluminum oxide (Al ₂ O ₃ ), yttrium aluminum composite oxide (at least 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 component. Yttrium zirconate is represented by, for example, a compositional formula of 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 means ceramics with a relative density of 96% or more, particularly 97% or more and 99.8% or less. This relative density is a percentage of the apparent density of the honeycomb structure 16 relative to the theoretical density of the ceramic.

In addition, regarding the theoretical density of ceramics, a part of the gas-permeable plugs 13 and 14 are pulverized, respectively, and the obtained powder is dissolved in a solution such as hydrochloric acid, and then analyzed by an ICP (Inductively Coupled Plasma) emission spectrometer (for example, , manufactured by Shimadzu Corporation (ICPS-8100)) to obtain the content of metal components.

Each component constituting the honeycomb structure 16 was identified by an X-ray diffraction apparatus using CuK α rays. When the identified component is Al ₂ O ₃ , it is converted into Al ₂ O ₃ using the value of the Al content determined by an ICP (Inductively Coupled Plasma) emission spectrometer. If the identified components are MgO and Na ₂ O, they can be converted into MgO and Na ₂ O, respectively, by the same method. The apparent density of the honeycomb structure 16 can be calculated|required based on JIS R 1634-1998.

In addition, when the main component constituting the ceramic is alumina, and the components other than the main component are magnesia, if the contents are set to a mass % and b mass %, respectively, alumina and magnesia can be used. The theoretical density (TD) of the ceramic was obtained from the value of the theoretical density (alumina=3.99 g/cm ³ , magnesium oxide=3.58 g/cm ³ ) 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 magnesia, the theoretical density (TD) of the ceramic is 3.96 g/cm ³ when calculated using the formula (1). The relative density was calculated|required by dividing the apparent density of the ceramic calculated|required based on JIS R 1634-1998 this theoretical density (TD) 3.96g/cm< ³ >.

The honeycomb structure 16 shown in FIGS. 4 and 5 has an outer peripheral area 16c and an inner peripheral area 16d. The outer peripheral area 16c includes the outer peripheral surface 16e along the axial direction; the inner peripheral area 16d excludes the outer peripheral surface. side area 16c.

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

When the outer peripheral side region 16c is the air-permeable plug 14, it means, for example, within 4.5% of the diameter from the outer peripheral surface 16e toward the radial direction with respect to the diameter of the honeycomb structure 16 in the cross section perpendicular to the axial direction. area.

The open porosity of each of the outer peripheral side region 16c and the inner peripheral side region 16d can be determined in accordance with JIS R 1634-1998. In any case, the difference in open porosity should just be 0.8% or more.

The main component in the present disclosure means the component which is the most abundant among the total 100 mass % of the components constituting the dense ceramic.

The root mean square slope (RΔq) of the roughness curve of the inner peripheral surface 16f forming the through holes 16a and 16b may 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 (RΔq) 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 determined by 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 concavities and convexities of the outer peripheral surface 16e become steep, when the honeycomb structure 16 is fixed to the electrostatic adsorption part 8, the insulating part 5, etc. with an adhesive agent, the adhesive agent moves along the inclination of the concavo-convex shape. 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 and 16b .

With such a configuration, the local slope of the inner peripheral surface 16f from one end surface to the other end surface increases or steeply slopes, and the length becomes substantially longer than the outer peripheral surface 16e, so the effect of suppressing arc discharge is achieved. become higher. When the honeycomb structure 16 is attached to 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, the number of particles detached from the honeycomb structure 16 is small. There are also few particles floating in the space in the chamber 1 . In addition, the stress concentration generated on the outer peripheral surface 16e is also relieved.

The root mean square slope (RΔq) can be measured according to JIS B 0601:2001 using a shape analysis laser microscope (manufactured by Keyence Co., Ltd., VK-X1100 or its successor). In terms of measurement conditions, 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 end effect is set to Yes, 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 each measurement range is along the length of the measurement range. The line that is set as the measurement object is pulled in the edge direction, and the line roughness is measured. The length set to be measured is, for example, 1320 μm.

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

The inner peripheral surface 16f and the ridge line 18 of the observation target surface 17 obtained by grinding the outer peripheral surface 16e toward the axis of the through holes 16a and 16b are used as the starting point, and the depth d is 10 μm or more and 20 μm The number of the following recesses 19 is 2 or less per ridge line 18 length 1 mm, preferably 1 or less. The concave portion 19 is, for example, a recessed shape. Grinding from the outer peripheral surface 16e of the honeycomb structure 16 toward the axis C is to facilitate the measurement of the depth d of the concave portion 19 . The direction of the depth d is the direction toward the outer peripheral surface 16e from the ridge line 18 in the observation target 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 determined in accordance with JIS B 0601:2013. In addition, in order to obtain the observation object surface 17 , WA (White Alundum) having 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 abrasive disc.

In addition, in the case of the honeycomb structure 16 with an outer diameter of 3 mm or more, cutting can be performed from the outer peripheral surface 16e of the honeycomb structure 16 toward the axis C, leaving a polishing margin of 0.1 mm or more and 0.2 mm or less, and then 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 (for example, 2.3 mm in width and 1.7 mm in length) of the observation object surface 17 captured by a scanning electron microscope is used as the object, using, for example, an image named

"(Hasamu Monosashi) free software is used to measure the depth d of the concave portion, and to calculate the number of the concave portion 19 whose depth d is 10 μm or more and 20 μm or less.

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

In this way, since the concave portion 19 hardly exists on the inner peripheral surface 16f, the occurrence of threshing (chipping) from the inner peripheral surface 16f as a starting point is suppressed. Therefore, even if a fluid such as gas passes through the through holes 16a and 16b, it is possible to reduce the situation where the detached particles become new particles and float in the plasma space P.

The concave portion 19 referred to here refers to a concave opening opened to the inner peripheral surface 16f, in other words.

」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。 In 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 magnitude of the deviation of the ridgeline 18 from a geometrically correct straight line. As far as the straightness is concerned, the image of the observation object surface 17 (eg horizontal 1.2 mm, vertical 1.4 mm) taken by an optical microscope can be used as the object, and the image named "

” free software to measure the straightness of the ridgeline 18. The axial direction of the through-holes 16a, 16b only needs to face the longitudinal direction of the image, so that the image includes at least one of the ridgelines 18 on the left and right of the inner peripheral surface 16f, and the length of the geometrically correct straight line is set as: 1.4mm is enough.

If the straightness of the ridgeline 18 is 20 μm or less, the inner peripheral surface 16f is in a state where there are hardly any large concave portions 19 in the form of sags. Therefore, even if the gas flow is turbulent, it is possible to reduce the amount of new particles floating in the electric current. Doubts in pulp space P.

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

The through holes 16a and 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 and 16b is high, the substantial flow paths in the axial direction of the through holes 16a and 16b are longer, so that it becomes easier to suppress the occurrence of arc discharge.

The cylindricity of the through holes 16a and 16b may be, for example, 0.05 mm or more and 0.2 mm or less. When the cylindricity of the through holes 16a and 16b is 0.05 mm or more, the distance over which the current flows can be extended, so that electrons are less likely to be accelerated, and arc discharges are less likely to occur. When the cylindricity of the through-holes 16a and 16b is 0.2 mm or less, the increase in the air permeability resistance of the cooling gas can be suppressed, the cooling efficiency can be maintained, and even if the through-holes 16a and 16b are repeatedly exposed to rising and falling temperatures, strain is not easily generated, so a long period of time can be covered. use.

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

With this structure, since the linear expansion coefficient of magnesium aluminate is higher than that of alumina, in the outer peripheral region 16c, in the cooling process of sintering, the crystal particles of magnesium aluminate are larger than the crystal particles of alumina in the outer periphery. Since the surface of the honeycomb structure 16 is moved in a way that the surface is raised, even if the honeycomb structure 16 is placed on the powder coating to reduce warpage or heat treatment is performed to remove strain after sintering, the outer periphery of the placed surface of the honeycomb structure 16 can be suppressed from becoming The noodles and the powder are melted.

On the other hand, in the inner peripheral side region 16d, the interval between the crystal particles of magnesium aluminate is small, that is, it is 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 high temperature ductility.

The interval between crystal particles of magnesium aluminate can be obtained by the following method. The cross-sections of the inner peripheral side region 16d and the outer peripheral side region 16c of the dense ceramic are observed at a magnification of 100 times, respectively, and the average range is selected, and the area is 1.044 mm ² (the lateral length is 1.18 mm) by, for example, a scanning electron microscope. mm, and the vertical length is 0.885 mm) to obtain a reflected electron image.

For this reflected electron image, an image analysis software "A IMAGE KUN (ver 2.52)" (registered trademark, manufactured by Asahi Kasei Engineering Co., Ltd.) was used, and it was later described as an image analysis software "A IMAGE KUN" , it means the shares of Asahi Kasei Engineering Image analysis software manufactured by Co., Ltd.), and the distance between the centers of gravity of the crystal particles of magnesium aluminate can be obtained by the method of the distance between the centers of gravity of the dispersion degree measurement.

The setting conditions of this method are, for example, set to 180 as the threshold value of the index indicating the lightness and darkness of the image, to set the brightness to be bright, to set the small pattern removal area to 10 μm ² , and to set the noise removal filter to none. In the above measurement, the threshold was set to 180, but the threshold can be adjusted according to the brightness of the observed image. If the brightness is set to bright, the method of binarization is set to manual, and the small pattern removal area is set to 10 μm ² and when the noise removal filter is set to none, it is only necessary to adjust the threshold value so that the marks appearing in the observation image match the shape of the crystal particles of magnesium aluminate.

In addition, when the comparison of the crystal particles of magnesium aluminate with other parts is difficult to identify, 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, the threshold value is set to 85, the brightness is set to dark, the small pattern removal area is set to 10 μm ² , and the noise removal filter is set to none.

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

Here, the magnesium aluminate was identified using an X-ray diffraction apparatus, and whether or not the crystal particles observed in the reflected electron image were magnesium aluminate, 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 may also contain silicon carbide as the main component and metal silicon. In this case, the silicon carbide content is, for example, 70 mass % or more and 92 mass % or less, and the metal silicon content is 8 mass % or more and 30 mass % or less. The mechanical properties of Young's modulus (dynamic modulus of elasticity) and 3-point flexural strength of silicon carbide are superior to those of metal silicon in Young's modulus (dynamic modulus of elasticity) and 3-point flexural strength. Therefore, when the content of silicon carbide is 70 mass % or more, the mechanical properties of the dense ceramic are improved. On the other hand, the thermal conductivity of metal silicon is higher than that of silicon carbide. Therefore, when the content of silicon carbide is 92 mass % or less, the thermal conductivity of the dense ceramic is improved. Therefore, when the content of silicon carbide is 70 mass % or more and 92 mass % or less, both mechanical properties and thermal conductivity can be achieved.

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

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 limited, and may be, for example, 8 μm or more and 20 μm or less. When this difference is 8 μm or more, the distribution density of silicon carbide becomes high. Therefore, the rigidity of the dense ceramic is improved, and the rigidity bias is also reduced. On the other hand, when the difference is 20 μm or less, the thermal conductivity of the dense ceramic is improved, and the tendency of the thermal conductivity is also reduced.

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

First, a part of the dense ceramic was cut out, and the average range was selected from the mirror surfaces obtained by polishing the cross section using diamond abrasive grains, and each area was 0.191 mm ² (lateral length by a scanning electron microscope) An observation image was obtained by photographing in a range of 351 μm and a vertical length of 545 μm).

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

As for the setting conditions of this method, the threshold value of the index indicating the lightness and darkness 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 equivalent circle diameter of silicon is obtained by the particle analysis method using the above-mentioned observation image as the object.

The setting conditions of this method are the same as those used in the distance method between centers of gravity. In addition, at least the outer peripheral surface of the honeycomb structure 16 may be provided with a first conductive portion formed of a layer or film having conductivity.

Recently, the high frequency (RF) electric power applied to the electrostatic attraction portion 8 has been gradually increased. When this high frequency electric power becomes high, abnormal discharge, such as arc discharge, may generate|occur|produce in the inside or the vicinity of the flow path 8d. That is, when high frequency (RF) power is applied to the substrate support assembly 3 , a potential difference is generated between the workpiece W and the inner surface of the electrostatic attraction part 8 due to the electrostatic capacitance of the electrostatic attraction part 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 a threshold value for generating discharge, abnormal discharge occurs.

When the outer peripheral surface is provided with the first conductive portion, since static electricity is easily removed along the outer peripheral surface, abnormal discharge in the flow path 8d is easily suppressed.

At least any one end surface of the honeycomb structure 16 may be provided with a second conductive portion composed of a layer or film having conductivity. When the end surface is provided with the second conductive portion, since static electricity is easily removed along the end surface 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 be provided with the 3rd conductive part which consists of a layer or film which has electroconductivity. When the inner peripheral surface is provided with the third conductive portion, since static electricity is easily removed along the inner peripheral surface, abnormal discharge in the flow path 8d can be further suppressed.

The term "having electrical conductivity" as used herein means that the surface resistance value is 10 ⁴ Ω or less. The surface resistance value may be determined by using a two-probe resistance meter (manufactured by PROSTAT, PRS-802) and setting the applied voltage to 100V.

The first conductive part, the second conductive part and the third conductive part are made of, for example, graphite, graphene, carbon nanotubes, fullerenes, amorphous carbon and DLC (Diamond-Like Carbon). Like Carbon) at least any one.

Furthermore, after immersion in hydrochloric acid having a concentration of 35% by mass and 72 hours from the start of immersion, the mass change C per unit area represented by the following formula (2) may 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 after 72 hours from the start of immersion, A: surface area (cm ² ) of the test piece before immersion)

When the mass change C per unit area is 0.3 g/cm ² or less, the particles constituting the first conductive part, the second conductive part and the third conductive part are not easily peeled off, so it can be immersed in hydrochloric acid for a long time, and the increase dirt removal effect.

As described above, the substrate support assembly 3 of the present disclosure includes the electrostatic adsorption member 8 and the air-permeable plugs 13 and 14 of the present disclosure. It is composed of plate-shaped ceramics with the adsorption surface 8a of the member W to be processed; The electrode 10 is located in the base material 8b, and the flow path 8d is located along the thickness direction of the base material 8b; the gas-permeable plugs 13 and 14 of the present disclosure are attached inside the flow path 8d.

The breathable plugs 13 and 14 are not prone to threshing, and even if the particles floating in the chamber 1 intrude into the through holes 16a and 16b, the particles are not easily adsorbed on the inner peripheral surface 16f, and because of their high mechanical strength, they can cover a long period of time. use.

In addition, the base material 8b and the air-permeable plugs 13 and 14 are composed 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 base material 8b. (content) higher. When the purity of alumina is increased, the corrosion resistance to plasma is improved, and the withstand voltage is increased, so the generation of arc discharge can be suppressed.

In particular, the purity of alumina in the air-permeable pins 13 and 14 may be 99.6 mass % or more. In addition, the content of calcium may be 0.01 mass % or less. When the calcium content is 0.01 mass % or less, even if the air-permeable plugs 13 and 14 are cleaned with citric acid, there is less calcium with low corrosion resistance to citric acid, so that the calcium source can be reduced to become particles and contaminate the cavity. Doubts in Room 1.

Further, as shown in FIG. 1( b ), the shower plate 2 may have the air-permeable plug 2d of the present disclosure attached to the inside of the second flow path 2c. With this configuration, it is possible to suppress the reverse flow of plasma and particles from the plasma space P toward the shower plate 2, and suppress the abnormal discharge generated in the second flow path 2c, thereby preventing the occurrence of abnormal discharge. resulting in a fire.

Next, an example of the manufacturing method of the breathable plug of this disclosure is demonstrated.

In order to obtain a gas-permeable plug composed of a dense ceramic mainly composed of alumina, first, a powder of alumina having a purity of 99.6 mass % or more and an average particle diameter (D50) of 1 μm or more and 3 μm or less is bonded to Binder, lubricant and solvent are mixed.

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

When it is desired to obtain a gas-permeable plug composed of dense ceramics with silicon carbide as the main component, firstly, coarse-grained powder and fine-grained powder are prepared as silicon carbide powder, and together with ion-exchanged water and dispersant, they are passed through a ball mill. Or bead mill to pulverize and mix for 40 to 60 hours to form a slurry. Here, the particle size ranges of the fine-grained powder and the coarse-grained powder after being pulverized and mixed are 0.4 μm or more and 4 μm or less, and 11 μm or more and 34 μm or less.

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

Regarding the mass ratio of the particulate powder to the coarse powder, for example, the particulate powder may be 6 mass % or more and 15 mass % or less, and the coarse powder may be 85 mass % or more and 94 mass % or less.

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

Lubricants are wax, glycerin, stearic acid and the like. The total amount of the lubricant can be 1 part by mass or more and 8 parts by mass or less in terms of solid content with respect to 100 parts by mass of the powder of alumina or silicon carbide.

In addition, the solvent is, for example, water, and ion-exchanged water, in particular, is preferable because the amount of impurities is small. The solvent is used so that the viscosity of the embryo soil in the kneading step is above 15000Pa·s and below 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 the alumina powder.

After mixing the alumina or silicon carbide powder, binder, lubricant and solvent at the above-mentioned mixing ratio, use a universal mixer or a 3-roll kneader to knead to obtain a viscosity of, for example, 15000Pa·s or more and 22000Pa· The embryo soil below s. The measurement of viscosity can be calculated|required by the flow characteristic evaluation method using a constant-load extrusion rheometer (Shimadzu Flow Tester CFT-500C by Shimadzu Corporation).

This green soil is formed using an extrusion molding machine equipped with a die for forming through-holes of the formed body to obtain a honeycomb-shaped formed body having a plurality of through-holes in the axial direction.

Here, since the root-mean-square slope (RΔq) in the roughness curves 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 have a length of, for example, 20 mm or more and 80 mm or less, drying is performed to remove moisture in the molded body. The drying temperature is, for example, 40 to 70°C. In the case where the main component of the dried formed body is alumina, the formed body is fired at a temperature of 1550°C to 1650°C for 0.5 hours or more and 5 hours in an atmospheric environment, whereby the air permeability of the present disclosure can be obtained. Sex plug.

In the case where the main component of the dried molded body is silicon carbide, in a nitrogen atmosphere, the temperature is set to 450°C or more and 650°C or less, and the holding time is set to 2 hours or more and 10 hours or less to carry out degreasing to obtain a degreased body. . Next, the degreased body is fired at a temperature of 1800°C to 2200°C for 0.5 hours or more and 5 hours or less in a decompressed atmosphere of an inert gas such as argon, whereby the gas permeable plug of the present disclosure can be obtained.

Another example of the manufacturing method of the breathable plug of the present disclosure will be described.

The manufacturing method of the breathable plug includes the following steps (a) to (e).

Step (a): The powder, wax, dispersant and plasticizer whose particle size is 6.5 μm or less with a particle size of 95% by volume of the cumulative distribution curve as the main components are stored in a container and stirred to obtain a slurry .

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

Step (c): the step of defoaming the preheated slurry.

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

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

Step (a) is a step of storing a raw material in a container and stirring to obtain a slurry. The raw materials are powder with alumina as the main component, wax, dispersant and plasticizer.

For powders containing alumina as the main component, the cumulative 95 vol% particle size 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 concave portion 19 in the inner peripheral surface 16f can be 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 a powder having a purity of, for example, 99.5% by mass or more can be used.

The cumulative distribution curve means a curve representing the cumulative distribution of particle diameters when the horizontal axis is the particle diameter and the vertical axis is the cumulative percentage of the particle diameter in a two-dimensional graph. The cumulative distribution curve can be obtained by the laser diffraction scattering method using, for example, a particle size distribution analyzer (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 A ratio of parts by mass or less is used. As a wax, paraffin wax, beeswax, etc. are mentioned, for example. As a dispersing agent, 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 said powder, wax, dispersing agent, and plasticizer are accommodated in the container heated to 90 degreeC or more and 140 degrees C or less, for example. At this time, the wax, dispersant, and plasticizer are liquid. The container is made of resin, for example. The container was attached to a stirrer, and the container was subjected to autorotation revolution (autorotation revolution kneading treatment) for 3 minutes, whereby the powder, wax, dispersant, and plasticizer were stirred to obtain a slurry.

In step (b), the slurry obtained in step (a) is preheated. By preheating, the fluidity of the slurry becomes high, and the effect obtained in the step (c) can be further enhanced. The preheating system is performed, for example, at a temperature of 120°C or higher and 180°C or lower.

In step (c), the slurry preheated in step (b) is supplied to the defoaming process. By performing the defoaming treatment, the air bubbles contained in the slurry can be reduced, so that a dense ceramic with a higher relative density can be obtained. In the defoaming treatment, for example, a syringe is filled with the obtained slurry, and defoaming is performed while rotating and revolving the syringe for 1 minute using a defoaming fixture.

In step (d), the slurry after defoaming treatment in step (c) is injected into a molding die to obtain a molded body. The molding die is a molding die with heating means surrounding the outer peripheral side. In this way, the honeycomb structure shown in FIG. 3 to FIG. 5 can be obtained by using the molding die surrounded by the heating means on the outer peripheral side. The heating means is not limited, for example, a heater and the like can be mentioned. By heating means, for example, heating can be performed so that the difference from the temperature of the slurry at the time of injection into the molding die is within 50°C. The shape of the molded 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 square column shape.

In the step (e), the formed body obtained in the step (c) is fired. The firing may be maintained at 1400° C. or higher and 1700° C. or lower for 1 hour or more and 3 hours or less, for example, in an atmospheric environment. In this way, the air-permeable plug of the present disclosure can be obtained, which is a honeycomb structure including a dense ceramic having a plurality of through holes in the axial direction. The air-permeable plugs 13 and 14 obtained in this way are obtained by grinding the inner peripheral surface 16f of 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. The ridgeline 18 of the observation object surface 17 is the starting point, and the number of the concave portions 19 having a depth d of 10 μm or more and 20 μm or less is 1 mm2 or less per length of the ridgeline 18 .

In order to obtain an air-permeable plug having at least the first conductive portion on the outer peripheral surface of the honeycomb structure, it is only necessary to coat or spray the outer peripheral surface of the dried molded body containing graphite, graphene, carbon nanotubes, fullerenes, non-ferrous metals, etc. After the 2-propanol (IPA) solution of carbon such as crystalline carbon, the above-mentioned firing may be performed.

In order to obtain an air-permeable plug having a second conductive portion on at least one end surface of the honeycomb structure, the above-mentioned 2-propanol (IPA) solution is applied or sprayed on the end surface of the dried molded body, and then the above-mentioned firing is performed. Can.

In order to obtain an air-permeable plug having a third conductive portion on the inner peripheral surface of the honeycomb structure, the above-mentioned 2-propanol (IPA) solution is coated or sprayed on the inner peripheral surface of the dried molded body, and then fired as described above. Can.

When at least one of the first conductive portion, the second conductive portion, and the third conductive portion is formed by DLC, the sintered body obtained by the above-mentioned firing can be formed with a plasma ion implantation method. After forming the film composed of DLC, the temperature may be set to 200° C. or higher and 1000° C. or lower, and heat treatment may be performed for 1 hour or longer.

The air-permeable plug of the present disclosure obtained by the above-mentioned manufacturing method is not easy to produce threshing, and even if the particles floating in the cavity invade into the through holes 16a and 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 section

2c: 2nd flow path

2d: breathable latch

Claims (18)

An air-permeable plug is provided with a honeycomb structure of dense ceramics, and the honeycomb structure of dense ceramics has a plurality of through holes in the axial direction. The breathable 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 breathable plug according to claim 1, wherein the open porosity of the outer peripheral region of the outer peripheral surface including 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 any one of claims 1 to 3, wherein the root mean square slope (RΔq) of the roughness curve of the inner peripheral surface forming the through hole is smaller than the outer peripheral surface of the honeycomb structure The root mean square slope (RΔq) of the roughness curve. The air-permeable plug according to any one of claims 1 to 3, wherein the root mean square slope (RΔq) of the roughness curve of the outer peripheral surface of the honeycomb structure is smaller than that of the inner peripheral surface forming the through hole The root mean square slope (RΔq) of the roughness curve. The air-permeable plug according to any one of claims 1 to 5, wherein an observation obtained by grinding an inner peripheral surface forming the through hole and grinding from an outer peripheral surface of the honeycomb structure toward the axis of the through hole The ridgeline of the target surface is the starting point, and the number of concave portions having a depth of 10 μm or more and 20 μm or less is 1 mm2 or less per ridgeline length. The air-permeable plug according to claim 6, wherein the straightness of the ridgeline on the observation object surface is 20 μm or less. The air-permeable plug according to any one of claims 1 to 7, wherein the dense ceramic is mainly composed of alumina and contains sodium, and the sodium content is 20 mass ppm or less. The gas-permeable plug according to claim 8, wherein the dense ceramic is mainly composed of aluminum oxide and contains magnesium aluminate; In the value after the average value of the equivalent circle diameters of the crystal particles of magnesium aluminate, the outer peripheral side region including the outer peripheral surface of the honeycomb structure is larger than the inner peripheral side region including the inner peripheral surface where the through holes are formed . The gas-permeable plug according to any one of claims 1 to 7, wherein the dense ceramic is mainly composed of silicon carbide and contains metal silicon. The gas-permeable plug according to claim 10, wherein the difference between the average distance between the centers of gravity of the metal silicon and the average value of the equivalent circle diameter of the metal silicon is 8 μm or more and 20 μm or less. The air-permeable plug according to any one of claims 1 to 11, wherein the honeycomb structure includes a first conductive portion formed of a conductive layer or film on at least an outer peripheral surface. The air-permeable plug according to any one of claims 1 to 12, wherein at least one of the end surfaces of the honeycomb structure is provided with a second conductive portion formed of a conductive layer or film. The breathable plug according to claim 12 or 13, wherein the inner peripheral surface of the honeycomb structure is provided with a third conductive portion formed of a layer or film having conductivity. The gas-permeable plug according to any one of claims 8 to 14, which is immersed in hydrochloric acid having a concentration of 35% by mass, and is expressed by the following formula (2) per unit area after 72 hours have elapsed from the start of immersion. Mass change C is less than 0.3g/ ^cm2 ; 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 after 72 hours from the start of immersion, A: surface area (cm ² ) of the test piece before immersion. A substrate support assembly is provided with an electrostatic adsorption member and the gas-permeable plug described in any one of claims 1 to 15; wherein, the electrostatic adsorption member has: a base material, which has a member to be processed adsorbed thereon. The adsorption surface and the plate-shaped ceramic on the opposite side of the adsorption surface are formed; the internal electrode is located in the substrate; and the flow path is located along the thickness direction of the substrate; the above-mentioned ventilation The sex plug is installed inside the aforementioned flow path. The substrate support assembly according to claim 16, 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 plugs than the base material. A shower plate comprising: a second base material composed of a plate-shaped ceramic having a plurality of second flow paths in a thickness direction through which a gas for plasma generation passes; and claims The air-permeable plug described in any one of 1 to 15 is attached to the inside of the second flow path.

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