TW202503964A - Electrostatic chuck device - Google Patents

Abstract

An electrostatic chuck device includes: an electrostatic chuck component, including a ceramic material as a material; a base, including a metal-based composite material as a material; and a bonding layer, connecting the electrostatic chuck component to the base, the bonding layer including a resin material and a thermally conductive filler, the absolute value of the difference in thermal expansion coefficient between the ceramic material and the metal-based composite material is less than 10 ppm/K, and the content of the thermally conductive filler in the bonding layer is greater than 50 mass % and less than 80 mass %.

Description

Electrostatic chuck device

The present invention relates to an electrostatic chuck device. This application claims priority based on Japanese Patent Application No. 2023-114086 filed on July 11, 2023, and the contents thereof are cited herein.

Previously, in the semiconductor manufacturing process of manufacturing semiconductors such as integrated circuits (IC), large scale integrated circuits (LSI), and very large scale integrated circuits (VLSI), an electrostatic chuck device is used to electrostatically adsorb plate-like samples when plasma processing is performed on plate-like samples such as silicon wafers. The temperature distribution of the plate-like sample held in the electrostatic chuck device during the processing is uniformly controlled so that the processing state of the plate-like sample during the plasma processing does not produce unevenness.

In recent years, with the diversification of semiconductor manufacturing processes, plate-shaped samples being processed are temperature-controlled in a wider temperature range than before. Therefore, ESD chuck devices are exposed to thermal cycles in a wider temperature range than before.

Therefore, an electrostatic chuck device has been proposed that includes an electrostatic chuck component made of ceramics and a base made of a metal matrix composite (MMC) that is a composite of metal and ceramics (see, for example, Patent Document 1).

In the electrostatic chuck device described in Patent Document 1, a metal brazing material is used to join an electrostatic chuck component to a base. In the electrostatic chuck device described in Patent Document 1, the amount of metal in the MMC as a material of the base is adjusted to reduce the thermal expansion difference with the ceramic plate to below the standard, thereby alleviating the thermal stress during brazing. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent Publication No. 11-163109

[Problem to be solved by the invention] When brazing a ceramic electrostatic chuck component and an MMC base, the electrostatic chuck component and the base are exposed to a high temperature (e.g., 500°C or more) at which the brazing material melts, and there is a risk of damage due to the heat load.

In addition, when the electrostatic chuck device that brazes the electrostatic chuck member and the base is heated in the plasma step, internal stress is generated due to the difference in thermal expansion coefficients of the electrostatic chuck member, the base, and the brazing material, which may cause damage such as interface peeling.

The present invention is made in view of such a situation, and its purpose is to provide a novel electrostatic chuck device using a base made of MMC. [Means for solving the problem]

The present invention provides an electrostatic chuck device, comprising: an electrostatic chuck component made of a ceramic material; a base made of a metal-based composite material; and a bonding layer for bonding the electrostatic chuck component to the base, the bonding layer comprising a resin material and a thermally conductive filler, the absolute value of the difference in thermal expansion coefficient between the ceramic material and the metal-based composite material being less than 10 ppm/K, and the content of the thermally conductive filler in the bonding layer being greater than 50% by mass and less than 80% by mass. That is, the first aspect of the present invention is the following electrostatic chuck device. [1] An electrostatic chuck device, comprising: an electrostatic chuck component, comprising a ceramic material as a material; a base, comprising a metal-based composite material as a material; and a bonding layer, bonding the electrostatic chuck component to the base, the bonding layer comprising a resin material and a thermally conductive filler, the absolute value of the difference in thermal expansion coefficient between the ceramic material and the metal-based composite material being less than 10 ppm/K, and the content of the thermally conductive filler in the bonding layer being greater than 50% by mass and less than 80% by mass.

The electrostatic chuck device of the first aspect of the present invention also preferably has the following features. The following features are also preferably combined in two or more. [2] The electrostatic chuck device as described in [1], wherein the thermally conductive filler is spherical.

[3] The electrostatic chuck device according to [1] or [2], wherein the thermally conductive filler has a bimodal particle size distribution.

[4] The electrostatic chuck device according to any one of [1] to [3], wherein the average particle size of the thermally conductive filler is less than or equal to 1/2 of the thickness of the bonding layer.

[5] An electrostatic chuck device as described in any one of [1] to [4], wherein a primer layer is formed on the surface of the base that is in contact with the bonding layer, and the primer layer is made of an organic silicon compound having a functional group and an alkoxy group that react with the resin material.

[6] An electrostatic chuck device as described in any one of [1] to [5], wherein, when the entire metal-based composite material is set to 100 volume %, the metal-based composite material contains 75 volume % or more of silicon carbide and contains 1 volume % or more and 25 volume % or less of Al, Si or Mg. [Effect of the Invention]

According to the present invention, a novel electrostatic chuck device using a base made of MMC can be provided.

[First embodiment] Hereinafter, an example of an electrostatic chuck device of the first embodiment as a preferred example of the present invention will be described with reference to FIG1. Furthermore, in all the following figures, the size or ratio of each component is appropriately different for the convenience of viewing the figures. Furthermore, this embodiment is specifically described for a better understanding of the purpose of the invention, and does not limit the present invention unless otherwise specified. For example, materials, quantities, types, quantities, sizes, shapes, positions, ratios, and other conditions may be changed, added, or omitted as needed unless otherwise specified.

Fig. 1 is a schematic cross-sectional view of an electrostatic chuck device 1A according to a first embodiment. The electrostatic chuck device 1A includes an electrostatic chuck member 2, a base 3, a bonding layer 4, a support plate 5, an insulator (insertion part) 23, and a power supply terminal 16. The electrostatic chuck member 2 and the base 3 are laminated with the bonding layer 4 interposed therebetween.

In this specification, the direction in which the electrostatic chuck component 2 and the base 3 are stacked is referred to as the stacking direction. Furthermore, the side on which the electrostatic chuck component 2 is arranged relative to the base 3 is referred to as one side of the stacking direction, and the opposite side is referred to as the other side of the stacking direction. In addition, in the following description, the up-down direction is used as the stacking direction to describe the various parts of the electrostatic chuck device 1A. However, the up-down direction here is only used to simplify the description and does not limit the posture of the electrostatic chuck device 1A when in use. Furthermore, the upper side is equivalent to one side of the stacking direction, and the lower side is equivalent to the other side of the stacking direction.

(Electrostatic chuck component) The electrostatic chuck component 2 has a dielectric substrate 11 and an adsorption electrode 13 located inside the dielectric substrate 11. A mounting surface 2a for adsorbing the wafer W is provided on the upper surface of the electrostatic chuck component 2. A focusing ring surrounding the wafer W may also be arranged on the outer side of the mounting surface 2a of the electrostatic chuck component 2.

The dielectric substrate 11 preferably includes a composite sintered body having sufficient mechanical strength and durability against corrosive gas and its plasma. As a material constituting the dielectric substrate 11, i.e., a dielectric material, it is preferable to use a ceramic (ceramic material) having mechanical strength and durability against corrosive gas and its plasma. That is, the dielectric substrate 11 is preferably formed of a ceramic material.

The ceramic constituting the dielectric substrate 11 preferably contains alumina (Al ₂ O ₃ ) as a main component. The so-called "main component" means that it accounts for 50 volume % or more of the whole. As needed, alumina may account for 60 volume % or more, 70 volume % or more, 80 volume % or more, 90 volume % or more, or 98 volume % or more of the whole. As the ceramic, for example, alumina (Al ₂ O ₃ ) sintered body, alumina (Al ₂ O ₃ )-silicon carbide (SiC) composite sintered body, etc. are preferably used. In particular, from the viewpoints of dielectric properties at high temperatures, high corrosion resistance, plasma resistance, and heat resistance, the material constituting the dielectric substrate 11 is preferably an Al ₂ O ₃ -SiC composite sintered body (hereinafter referred to as Al ₂ O ₃ -SiC). The thermal expansion coefficient of the ceramic material can be arbitrarily selected from the values of the thermal expansion coefficients of the materials. For example, 4 ppm/K to 8 ppm/K or 6 ppm/K to 8 ppm/K can be cited as examples.

The dielectric substrate 11 is a circular plate or a substantially circular plate in a plan view. The dielectric substrate 11 has a mounting surface 2a for mounting the wafer W and a back surface 2b facing the opposite side of the mounting surface 2a. For example, a plurality of protrusions (not shown) may be formed at predetermined intervals on the mounting surface 2a. In this case, the mounting surface 2a supports the wafer W using the front ends of the plurality of protrusions.

The adsorption electrode 13 is arranged inside the dielectric substrate 11. The adsorption electrode 13 preferably extends in a plate shape along the mounting surface 2a of the dielectric substrate 11. The adsorption electrode 13 generates an electrostatic adsorption force to hold the wafer W on the mounting surface 2a of the dielectric substrate 11 by applying a voltage. The adsorption electrode 13 is connected to a power supply terminal 16 for applying a DC voltage to the adsorption electrode 13.

The adsorption electrode 13 is preferably composed of a composite of an insulating substance and a conductive substance. The insulating substance contained in the adsorption electrode ₁₃ is not particularly limited, and is preferably at least one selected _from the group consisting of aluminum oxide ( _Al2O3 ), aluminum nitride ( _AlN ), silicon nitride ( _Si3N4 ), yttrium (III) oxide ( _Y2O3 ), yttrium aluminum garnet (YAG) and _SmAlO3 . The conductive material contained in the adsorption electrode 13 is preferably at least one selected from the group consisting of molybdenum carbide (Mo ₂ C), molybdenum (Mo), tungsten carbide (WC), tungsten (W), tantalum carbide (TaC), tantalum (Ta), silicon carbide (SiC), carbon black, carbon nanotubes, and carbon nanofibers.

The thickness of the electrostatic chuck component 2 can be selected arbitrarily, but is preferably 0.5 mm to 5 mm. It can also be 0.5 mm to 1.5 mm, 1.5 mm to 3.0 mm, 3.0 mm to 5.0 mm, etc. If the thickness of the electrostatic chuck component 2 is 0.5 mm or more, the withstand voltage of the electrostatic chuck component 2 becomes higher. In addition, if the thickness of the electrostatic chuck component 2 is 5 mm or less, the heat capacity of the electrostatic chuck component 2 becomes smaller, so it is easy to evenly maintain the temperature of the plate-shaped sample as the processing object during plasma processing.

The thermal expansion coefficient of the electrostatic chuck component 2 can be approximated by the thermal expansion coefficient of the dielectric substrate 11 constituting the electrostatic chuck component 2. For example, when the material of the dielectric substrate 11 is _Al2O3 - _SiC , the thermal expansion coefficient of the electrostatic chuck component 2 can be considered to be 7.0 ppm/K to 8.0 ppm/K (7.0× ^10-6 /K to 8.0× ^10-6 /K) (@25°C to 100°C). The above value can also be calculated based on the difference in expansion at 100°C and 25°C. According to the proportion of _Al2O3 , it can also be considered to be 7.0 ppm/ _K to 7.3 ppm/K, 7.3 ppm/K to 7.6 ppm/K, or 7.6 ppm/K to 8.0 ppm/K, etc.

(Base) The base 3 supports the electrostatic chuck component 2 from the bottom. The base 3 is provided with a supporting surface 3a facing upward and a lower surface 3b facing downward. The supporting surface 3a faces the back surface 2b of the dielectric substrate 11 in the vertical direction via the bonding layer 4. The base 3 supports the electrostatic chuck component 2 on the supporting surface 3a.

A flow path 3f for circulating a coolant is preferably provided inside the base 3. The coolant flowing in the flow path 3f can be arbitrarily selected, and for example, liquid or gas such as water or an organic solvent is preferably used. The flow path 3f extends along the supporting surface 3a. The coolant in the flow path 3f cools the base 3 as a whole, and cools the electrostatic chuck component 2 through the supporting surface 3a.

The base 3 is a disc-shaped or substantially disc-shaped component in a top view, and is preferably formed of a metal-based composite material. The metal-based composite material is preferably a material with a thermal conductivity of 140 W/m·K or more. If necessary, the thermal conductivity may also be 170 W/m·K to 260 W/m·K or 180 W/m·K to 240 W/m·K. The upper limit of the thermal conductivity may be arbitrarily selected, for example, it may be less than 240 W/m·K. In this specification, the so-called "top view" refers to the field of view observed from the thickness direction of the electrostatic chuck component 2.

The base 3 can be formed using a known metal composite (hereinafter referred to as MMC) as a material. MMC can be conditioned, for example, by a known method (metal infiltration method or forging method) of introducing a metal such as Al or Si into the pores of a porous ceramic substrate after conditioning, i.e., after formation. The porous ceramic substrate is also preferably made of SiC.

In more detail, the MMC as the material of the base 3 preferably contains SiC as a material. The amount of SiC can be arbitrarily selected. In detail, when the entire base 3 is set to 100 volume %, the material of the base 3 preferably contains 20 volume % or more and less than 100 volume % of SiC, and more preferably contains 20 volume % or more and 99 volume % or less of SiC. As needed, the amount of SiC may be 20 volume % or more and 40 volume % or less, 40 volume % or more and 60 volume % or less, 60 volume % or more and 80 volume % or less, 75 volume % or more and 90 volume % or less, or 80 volume % or more and 99 volume % or less. In addition to SiC, the base 3 preferably contains one or more elements (metal elements) selected from the group consisting of aluminum (Al), silicon (Si) and magnesium (Mg). By including these elements in SiC, the thermal conductivity of the base 3 is improved, and heat dissipation through the base 3 becomes easy. The total amount of the elements can be selected arbitrarily. For example, when the entire base 3 is set to 100 volume%, it can be 1 volume% or more and 80 volume% or less, preferably 1 volume% or more and 70 volume% or less. If necessary, it can also be 1 volume% or more and 20 volume% or less, or 20 volume% or more and 40 volume% or less, or 40 volume% or more and 60 volume% or less, or 60 volume% or more and 80 volume% or less. The thermal expansion coefficient of MMC as the material of the base 3 can be arbitrarily selected, and may be, for example, 2.8 ppm/K to 4.0 ppm/K or 4.0 ppm/K to 7.0 ppm/K. For example, in a material containing 75 volume % or more of SiC, which is preferably used as the material of the base 3, the thermal expansion coefficient can be controlled within a range of, for example, 2.8×10 ^-6 /K to 6.8× ^{10 -6} /K (2.8 ppm/K to 6.8 ppm/K) by adjusting the type or amount of the target material such as metal contained in the material (ceramic substrate). As required, the thermal expansion coefficient may also be controlled within the range of 2.8×10 ^-6 /K to 4.0×10 ^-6 /K, 4.0×10 ^-6 /K to 5.5×10 ^-6 /K, or 5.5×10 ^-6 /K to 6.8× ^{10 -6} /K.

The absolute value of the difference in thermal expansion coefficient between the MMC as the material of the base 3 and the ceramic material as the material of the electrostatic chuck component 2 is 10 ppm/K or less, preferably 9.0 ppm/K or less, more preferably 8.0 ppm/K or less, and further preferably 7.0 ppm/K or less. It may be 5.0 ppm/K or less, 3.0 ppm/K or less, or 1.0 ppm/K or less as required. By the dosage of the base 3 and the material of the electrostatic chuck component 2 being in the above relationship, it is easy to suppress the internal stress caused by thermal deformation during heating. The lower limit of the absolute value of the difference may be 0 ppm/K, or may be 0.1 ppm/K or 0.5 ppm/K.

For example, when the entire base 3 is set to 100 volume %, the material of the base 3 preferably contains 75 volume % or more and 99 volume % or less of SiC, and contains 1 volume % or more and 25 volume % or less of Al, Si or Mg. The thermal expansion coefficient of the base 3 with such a composition is very close to the thermal expansion coefficient of Al ₂ O ₃ -SiC constituting the electrostatic chuck component, and the difference in thermal expansion amount with the electrostatic chuck component 2 becomes small when heated.

As MMC, for example, Mg-SiC (7.0 ppm/K), Al-SiC (6.8 ppm/K), Si-SiC (2.8 ppm/K), etc. can be preferably used. The amount of metal contained in each MMC can be appropriately adjusted within the above content range according to the desired thermal expansion coefficient.

The surface of the base 3 is preferably coated with a metal film as needed. As the metal film, for example, an Al spray film can be used. The film thickness of the metal film can be arbitrarily selected, for example, it can be set to be greater than 100 μm and less than 300 μm. With this structure, the base 3 can be used as an internal electrode for plasma generation. The base 3 is connected to the external high-frequency power supply 22 via a matching device (not shown).

The base 3 is provided with a hole 17. The hole 17 extends in the up-down direction. The hole 17 penetrates the base 3 in the up-down direction and opens at the support surface 3a and the lower surface 3b of the base 3, respectively. The hole 17 is, for example, circular or substantially circular in a plan view. An insulator 23 described later is inserted into the hole 17. In FIG. 1 , the hole 17 is shown to penetrate the base 3 in the up-down direction, but the hole 17 does not necessarily penetrate the base 3 as long as it opens at least at the support surface 3a and the insulator 23 is inserted inside.

(Connection layer) The connection layer 4 is clamped by the electrostatic chuck component 2 and the base 3 to connect the electrostatic chuck component 2 and the base 3. The connection layer 4 includes a resin material and a thermally conductive filler (hereinafter referred to as a filler).

The bonding layer 4 made of resin material is relatively easier to deform than the electrostatic chuck member 2 and the base 3. Therefore, the bonding layer 4 is easier to follow and deform when the electrostatic chuck member 2 and the base 3 expand or contract due to temperature changes, compared with a bonding layer formed by brazing using a brazing material such as an alloy. In addition, for example, even if there is a difference in the amount of thermal expansion of the electrostatic chuck member 2 and the amount of thermal expansion of the base 3, the internal stress caused by the difference in the amount of thermal expansion can be suppressed by the deformation of the bonding layer 4.

The resin (resin material) contained in the bonding layer 4 is not particularly limited as long as it is a resin that is not easily broken by cohesion due to thermal stress, and preferably includes silicone resin, acrylic resin, epoxy resin, phenol resin, polyurethane resin, unsaturated polyester resin, etc. Among these, silicone resin is preferred from the viewpoint of high elongation and being not easily broken by cohesion due to changes in thermal stress.

The filler (thermally conductive filler) contained in the bonding layer 4 has a function of increasing the thermal conductivity of the bonding layer 4 in the thickness direction. As fillers having the above function, preferably one or more selected from the group consisting of inorganic oxides, inorganic nitrides, and inorganic oxynitrides can be listed. The filler can be used alone or in combination of two or more. It can also be a filler formed by combining two or more of the oxides or nitrides. For example, as preferred examples of the inorganic oxides, Al ₂ O ₃ , MgO, etc. can be listed. As preferred examples of the inorganic nitrides, AlN, BN, SiN, etc. can be listed. The filler can also be a surface-coated filler. For example, as a preferred example of the filler, there can be cited surface-coated aluminum nitride (AlN) particles in which a coating layer containing silicon oxide (SiO ₂ ) or aluminum oxide (Al ₂ O ₃ ) is formed on the surface of aluminum nitride (AlN) particles.

The content of the filler in the bonding layer 4 is 50% by mass or more and 80% by mass or less. The content of the filler is preferably 55% by mass or more, and more preferably 60% by mass or more. In addition, the content of the filler is preferably 75% by mass or less, and more preferably 70% by mass or less. The upper limit and lower limit of the content of the filler can be arbitrarily combined.

When the content of the filler is above the lower limit, sufficient thermal conductivity can be imparted to the bonding layer 4, and heat transfer from the electrostatic chuck member 2 to the base 3 can be promoted. When the content of the filler is below the upper limit, the electrostatic chuck member 2 and the base 3 easily follow and deform when they expand or contract due to temperature changes.

In the case of using an adhesive layer containing a resin material, Al is used as the material of the base in a known electrostatic chuck device. A base made of Al, i.e., a base formed of aluminum, has a larger thermal expansion coefficient than a ceramic electrostatic chuck component and greatly deforms when heated. Therefore, when the electrostatic chuck component and the base thermally expand in the plasma step, the difference in thermal expansion between the electrostatic chuck component and the base is large, and the adhesive layer containing the resin material may be broken. However, the base 3 of this embodiment is made of MMC, so the difference in thermal expansion with the electrostatic chuck component 2 can be reduced, and the breakage of the adhesive layer can be suppressed.

Furthermore, in the electrostatic chuck device 1A of the present embodiment, by using the base 3 made of MMC, the deformation amount required for the bonding layer to absorb the thermal expansion of the electrostatic chuck component 2 and the base 3 can be smaller than that of the electrostatic chuck device using the Al base. Therefore, compared with the electrostatic chuck device using the Al base, the amount of filler contained in the bonding layer can be increased to 50 mass % or more and 80 mass % or less, and the thermal conductivity of the bonding layer can be further improved.

If the filler contained in the adhesive layer 4 increases, the filler tends to aggregate when the pre-cured resin material (adhesive) and the filler are kneaded, and it tends to be difficult to disperse the filler in the resin. In order to promote the dispersion of the filler during kneading, the filler is preferably spherical rather than plate-like or fibrous.

In order to facilitate dispersion of the filler during kneading, the filler preferably has a bimodal particle size distribution.

The shape of the filler and the bimodal distribution of the filler particle size can be confirmed by the following method.

First, the electrostatic chuck member 2 or the base 3 is peeled off from the electrostatic chuck device 1A to expose the bonding layer 4. The surface of the exposed bonding layer 4 is processed to be flat by ion milling. A scanning electron microscope (SEM) image of the obtained cross section is photographed, and the particle size of each of the multiple fillers contained in the obtained image is measured by image analysis. The particle size of the filler can be obtained by analyzing it, for example, using image analysis software attached to the SEM as described later. For example, an equivalent circle diameter (diameter when converted to a circle of the same area) or an equivalent spherical diameter (diameter when converted to a sphere of the same volume) may be obtained from the area of the obtained filler and used as the particle size.

The magnification of the SEM image is not limited as long as the particle size of the filler contained in the bonding layer 4 can be measured, but it can be a magnification that includes at least 200 fillers in one field of view of the SEM image. The magnification of the SEM image can be, for example, 100 to 5000 times. The number of fillers to be measured can be arbitrarily selected, for example, it can also be 200.

In addition, the shape of the filler contained in the SEM image (plate-like, fibrous, or spherical) is confirmed based on the obtained image or measured value. The shape of the filler can be confirmed by visual inspection of the SEM image, for example, but can also be confirmed from a product catalog or the like.

In addition, the particle size distribution of the filler contained in the SEM image is determined based on the obtained measured values to confirm whether it is a bimodal particle size distribution.

In this embodiment, the filler is "bimodal", which means that there are two or more, preferably two, peaks showing extremely large values in the particle size distribution (frequency distribution) obtained by the method. For example, it means that in a graph of particle size distribution (at least one of number distribution and volume distribution) with particle size on the horizontal axis and the number of particles or frequency % on the vertical axis, two or more peaks can be observed. The so-called peak value may also refer to a position having a value significantly larger than the positions on both sides thereof. In addition, in addition to the above method, the filler used as the material of the electrostatic chuck device 1A can also be judged by measuring the particle size distribution of the filler by a known laser diffraction scattering method. For example, if necessary, the filler before being added to the adhesive can be used to measure the average particle size or particle size distribution of the filler by a known laser diffraction scattering method.

The average particle size of the thermally conductive filler contained in the bonding layer 4 can be arbitrarily selected, but is preferably less than 1/2 of the thickness of the bonding layer 4, more preferably greater than 1/2000 and less than 1/2, and further preferably greater than 1/200 and less than 1/2. If necessary, it may be greater than 1/1000 and less than 1/500, or greater than 1/500 and less than 1/100, or greater than 1/100 and less than 1/10, or greater than 1/10 and less than 1/3, etc. More specifically, when the average particle size of the thermally conductive filler is greater than 1 μm and less than 100 μm, the thickness of the bonding layer 4 is preferably greater than 2 μm and less than 200 μm. If necessary, the thickness may be 2 μm to 20 μm, 10 μm to 40 μm, 30 μm to 80 μm, 50 μm to 150 μm, 100 μm to 200 μm, etc. By setting the thickness of the bonding layer 4 in this way, it is easy to form the bonding layer 4 containing the filler into a uniform thickness, which can reduce cooling unevenness (improve thermal uniformity).

As described above, the average particle size of the filler can be obtained from the SEM image by image analysis. For example, it can also be the average value of the particle sizes of 200 fillers. The average particle size of the filler can also be, for example, D50, which is the equivalent spherical diameter.

The thermal conductivity of the bonding layer 4 is preferably 0.3 W/mK or more, more preferably 0.6 W/mK or more, and further preferably 1.0 W/mK or more. If the bonding layer 4 has such a thermal conductivity, heat can be properly transferred from the electrostatic chuck component 2 to the base 3, and the entire device can be properly cooled. The upper limit of the thermal conductivity can be arbitrarily selected.

In addition, the elastic modulus of the bonding layer 4 at 25°C is preferably 10000 MPa or less, more preferably 6000 MPa or less, further preferably 3000 MPa or less, and particularly preferably 1000 MPa or less. It may be 800 MPa or less or 500 MPa or less as needed. When the electrostatic chuck device 1A is used to repeatedly perform heating and cooling in the plasma step, the bonding layer 4 may sometimes be delaminated due to the internal stress caused by the thermal expansion difference between the electrostatic chuck component 2 and the base 3. In contrast, if the bonding layer 4 has the above-mentioned elastic modulus, the bonding layer 4 can alleviate the above-mentioned internal stress and suppress delamination. The lower limit value of the elastic coefficient of the next layer 4 at 25°C can be arbitrarily selected as needed.

The thermal conductivity and elastic modulus can be controlled by adjusting the amount or type of filler added. The following Tables 1 and 2 show the thermal conductivity when each filler (aluminum oxide or aluminum nitride) is added to the silicone resin, the elastic modulus at 25°C, and whether or not peeling occurs after the MMC base (SiC82 volume %, Si18 volume %) and the ceramic material (Al ₂ O ₃ -SiC) are bonded together using the filler. In the table, ○ means no peeling, and × means peeling. In addition, the following is performed under the same conditions for all samples. The presence or absence of peeling is confirmed using an ultrasonic flaw detector and a three-dimensional measuring device. In addition, the thermal conductivity is measured by the laser flash method.

[Table 1] Alumina addition amount [vol%] Resin addition amount [vol%] Thermal conductivity [W/m·K] Modulus of elasticity @25℃ [MPa] Is there any peeling after MMC/ceramic material bonding? 0 100 0.2 30 ○ 40 60 0.8 42 ○ 50 50 1.3 68 ○ 60 40 2.0 160 ○ 70 30 3.5 350 ○ 80 20 5.5 810 ○ 90 10 8.0 1670 ×

[Table 2] Aluminum nitride addition amount [vol%] Resin addition amount [vol%] Thermal conductivity [W/m·K] Modulus of elasticity @25℃ [MPa] Is there any peeling after MMC/ceramic material bonding? 0 100 0.2 30 ○ 40 60 0.9 60 ○ 50 50 1.4 120 ○ 60 40 2.5 200 ○ 70 30 4.5 450 ○ 80 20 7.0 990 ○ 90 10 10.0 1800 ×

The adhesive layer 4 may be formed by sandwiching a liquid adhesive containing a thermally conductive filler between the electrostatic chuck member 2 and the base 3 and curing the adhesive, or may be formed by sandwiching a sheet or film adhesive containing a thermally conductive filler between the electrostatic chuck member 2 and the base 3 .

When the material of the adhesive layer 4 is a liquid adhesive, the viscosity of the adhesive is preferably 500 Pa·s or less. If necessary, the viscosity may be 300 Pa·s or less, 100 Pa·s or less, or 30 Pa·s or less.

As described above, if the amount of filler contained in the adhesive layer 4 increases, the adhesive force between the adhesive layer 4 and the base 3 is likely to decrease. Therefore, it is preferable to form a primer layer on the surface of the base 3 that contacts the adhesive layer 4.

The base coating layer is preferably made of an organic silicon compound having a functional group and an alkoxy group that react with the resin material (adhesive) as the material of the bonding layer 4. As the functional group, at least one selected from an epoxy group, a vinyl group, a methacrylic group, and a hydroxyl group can be exemplified. In addition, the organic silicon compound preferably has one or more alkoxy groups. Furthermore, the organic silicon compound can be a single molecule or a polymer. As such an organic silicon compound, a known compound can be used as a material for the base coating layer.

When such an organic silicon compound is applied to the surface of the base 3, the alkoxy group of the organic silicon compound reacts with the surface of the base 3 to form a bond. In addition, the functional group of the organic silicon compound reacts with the adhesive forming the adhesive layer to form a bond. Thus, when the primer layer is formed, a higher adhesive force is generated between the adhesive layer 4 and the base 3 compared to the case without the primer layer.

(Supporting plate) The supporting plate 5 supports the base 3 from the lower surface 3b of the base 3. The supporting plate 5 preferably includes a material having a higher Young's modulus than the material of the base 3. For example, any one of metal, MMC, and ceramic can be used as the material of the supporting plate 5. Among them, as the supporting plate 5, it is preferable to use a ceramic plate such as _Al2O3 having a higher Young's modulus than the base ₃ .

The ceramic used in the support plate 5 is preferably the same material as that used in the electrostatic chuck member 2. Specific examples of ceramics include aluminum oxide and aluminum nitride. By using the same material in the support plate 5 and the electrostatic chuck member 2, the difference in thermal expansion coefficient between the support plate 5 and the electrostatic chuck member 2 can be reduced, and the warping of the electrostatic chuck device 1A can be suppressed.

(Insulator) The insulator 23 is inserted into the hole 17 and assembled to the base 3. That is, the insulator 23 functions as an insertion part inserted into the hole 17. The insulator 23 is cylindrical and extends in the up-down direction (lamination direction). The power supply terminal 16 is arranged inside the insulator 23. The outer peripheral surface of the insulator 23 is preferably joined to the inner side surface of the hole 17 using a joining method such as welding. The insulator 23 insulates the metal base 3 from the power supply terminal 16.

The insulator 23 can be formed of a material selected arbitrarily, for example, ceramic can be used as a forming material. That is, the insulator 23 is preferably formed of an insulating member. Thereby, the insulator 23 can suppress the gas introduction hole from becoming a starting point of abnormal discharge. The insulator 23 has durability for plasma. As an example of ceramic constituting the insulator 23, one or more ceramics selected from AlN, Al ₂ O ₃ , Si ₃ N ₄ , zirconia (ZrO ₂ ), silicon aluminum oxynitride (Sialon), boron nitride (BN), and SiC can be used.

An end surface (hereinafter referred to as an upper end surface 23 a ) of the upper side (one side in the stacking direction) of the insulator 23 abuts against the electrostatic chuck member 2 or is disposed between the electrostatic chuck member and the electrostatic chuck member via an insulating adhesive.

(Power supply terminal) The power supply terminal 16 extends downward from the adsorption electrode 13. The power supply terminal 16 is connected to an external power source 21. The power source 21 applies voltage to the adsorption electrode 13. The number and shape of the power supply terminal 16 can be selected arbitrarily, and can be determined according to the form of the adsorption electrode 13, that is, whether it is a monopolar type or a bipolar type.

The power supply terminal 16 passes through the first hole 17a of the dielectric substrate 11, the second hole 17b of the bonding layer 4, and the third hole 17c of the support plate 5. Furthermore, an insulator 23 is interposed between the power supply terminal 16 and each of the second hole 17b of the bonding layer 4 and the third hole 17c of the support plate 5. The first hole 17a is provided at a portion of the dielectric substrate 11 that is lower than the adsorption electrode 13.

The first hole 17a, the second hole 17b, and the third hole 17c are circular when viewed from the stacking direction. The first hole 17a, the second hole 17b, and the third hole 17c are connected to the hole portion 17 of the base 3.

In addition, when viewed from the stacking direction, the inner circumference of the first hole 17a is connected to the inner circumference of the insulator 23. The inner diameter of the first hole 17a is substantially equal to the inner diameter of the insulator 23 and slightly larger than the outer diameter of the power supply terminal 16. The inner diameters of the second hole 17b and the third hole 17c are substantially equal to the outer diameter of the insulator 23.

By using the electrostatic chuck device having the above-described structure, a novel electrostatic chuck device using a base made of MMC can be provided.

The preferred embodiment of the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to the embodiment. The various shapes or combinations of the components shown in the above embodiment are examples, and various changes can be made based on design requirements within the scope of the present invention.

1A: Electrostatic chuck device 2: Electrostatic chuck component 2a: Loading surface 2b: Back surface 3: Base 3a: Support surface 3b: Lower surface 3f: Flow path 4: Adhesive layer 5: Support plate 11: Dielectric substrate 13: Adsorption electrode 16: Power supply terminal 17: Hole 17a: First hole 17b: Second hole 17c: Third hole 21: Power supply 22: High-frequency power supply 23: Insulator 23a: Upper end surface W: Wafer

FIG1 is a schematic cross-sectional view showing a preferred example of an electrostatic chuck device 1A according to a first embodiment.

Claims (6)

An electrostatic chuck device comprises: An electrostatic chuck component comprising a ceramic material as a material; A base comprising a metal-based composite material as a material; and A bonding layer bonding the electrostatic chuck component to the base, The bonding layer comprises a resin material and a thermally conductive filler, The absolute value of the difference in thermal expansion coefficient between the ceramic material and the metal-based composite material is less than 10 ppm/K, The content of the thermally conductive filler in the bonding layer is greater than 50% by mass and less than 80% by mass. An electrostatic chuck device as described in claim 1, wherein the thermally conductive filler is spherical. An electrostatic chuck device as described in claim 1 or 2, wherein the thermally conductive filler has a bimodal particle size distribution. The electrostatic chuck device according to claim 1 or 2, wherein the average particle size of the thermally conductive filler is less than 1/2 of the thickness of the bonding layer. The electrostatic chuck device as described in claim 1 or 2, wherein a primer layer is formed on the surface of the base that contacts the bonding layer, and the primer layer is made of an organic silicon compound having a functional group and an alkoxy group that react with the resin material. An electrostatic chuck device as described in claim 1 or 2, wherein, when the entire metal-based composite material is set to 100 volume %, the metal-based composite material contains 75 volume % or more of silicon carbide and contains 1 volume % or more and 25 volume % or less of Al, Si or Mg.