High-dielectric-constant, thermally conductive composition and high-dielectric-constant, thermally conductive member

Abstract

Provided are: a high-dielectric-constant, thermally conductive member that provides electrical insulation, has appropriate flexibility, and has both high thermal conductivity and high dielectric characteristics; and a high-dielectric-constant, thermally conductive composition capable of forming the high-dielectric-constant, thermally conductive member.　The high-dielectric-constant, thermally conductive composition comprises (A) a resin and (B) a thermally conductive filler. The content of the thermally conductive filler (B) is 50-88% by volume of the entire composition. The thermally conductive filler (B) includes (b1) a first thermally conductive filler having a volume resistivity of 1.0 × 10 to 1.0 × 108 Ω·cm. The content of the first thermally conductive filler (b1) is 7-35% by volume of the entire composition.

Description

Highly dielectric thermally conductive composition and highly dielectric thermally conductive member

[0001] The present invention relates to a highly dielectric thermally conductive composition and a highly dielectric thermally conductive member made from the cured product thereof, and more particularly to a thermally conductive member for suppressing a temperature rise in a substrate being etched in a semiconductor etching apparatus, and a thermally conductive composition forming the same.

[0002] In semiconductor etching equipment, a thermally conductive member is disposed between the outer periphery of a chuck mechanism on which a substrate to be processed, such as a wafer, is placed and an edge ring attached to the outer periphery of the substrate to dissipate heat transferred to the edge ring during the etching process. The thermally conductive member can be obtained, for example, by mixing a thermally conductive filler with excellent thermal conductivity, such as a metal oxide or nitride, such as alumina, into a rubber base material such as silicone, followed by curing or molding. This type of thermally conductive filler has high thermal conductivity but a low dielectric constant, resulting in poor dielectric properties as a thermally conductive member.

[0003] Electrostatic chucks are widely used as chuck mechanisms in semiconductor etching equipment. All components used in electrostatic chucks, except for the thermally conductive components, are made of dielectric materials with high dielectric constants. Therefore, if the thermally conductive components could also have a high dielectric constant, the difference in dielectric constant between components in the etching equipment would be reduced, potentially improving yield during etching. Patent Document 1, for example, proposes a technique for imparting a high dielectric constant to thermally conductive components. This technique involves mixing high-dielectric-constant fine particles, such as barium titanate, with thermally conductive fine particles, such as nitrides, in a polymer substrate to form a high-dielectric insulating heat-dissipating sheet that combines a high dielectric constant with heat dissipation properties.

[0004] JP 2013-8724 A

[0005] However, in Patent Document 1, high-dielectric-constant fine particles such as barium titanate are used to obtain a high dielectric constant, but because the high-dielectric-constant fine particles have poor thermal conductivity, a sheet (thermal conductive member) obtained by mixing the high-dielectric-constant fine particles and the thermally conductive fine particles has a problem of reduced thermal conductivity. Therefore, in a semiconductor etching apparatus that uses high-frequency current, a large amount of heat must be dissipated and the environment is severe, so a reduction in the thermal conductivity of the thermal conductive member is undesirable. Therefore, it is desirable for the thermal conductive member to have high thermal conductivity while also having high dielectric properties, such as a high dielectric constant equivalent to the dielectric constant of the chuck mechanism and its surrounding components of the semiconductor etching apparatus to be used, and a sufficiently low dielectric loss tangent tanδ.

[0006] Furthermore, in a semiconductor etching apparatus, in order to uniformly process the surface of a wafer, it is undesirable for the edge ring and chuck mechanism to be electrically conductive, and it is therefore desirable for the heat conductive member to have electrical insulation. Also, the heat conductive member disposed between the outer periphery of the chuck mechanism of the semiconductor etching apparatus and the edge ring installed on the outer periphery of the substrate to be processed must have a moderate degree of flexibility so that it can be attached without any gaps between the outer periphery and the edge ring.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a highly dielectric thermally conductive member that has electrical insulation properties and appropriate flexibility, as well as high thermal conductivity and high dielectric properties, and a highly dielectric thermally conductive composition that can be used to form the same.

[0008] In order to achieve the above object, the highly dielectric thermally conductive composition according to the present invention contains a resin (A) and a thermally conductive filler (B). The content of the thermally conductive filler (B) is 50 to 88 volume % of the entire composition, and the thermally conductive filler (B) has a volume resistivity of 1.0 × 10 to 1.0 × 10. ８The highly dielectric thermally conductive composition according to the present invention contains a first thermally conductive filler (b1) having a dielectric constant of Ω·cm. In the highly dielectric thermally conductive composition according to the present invention, the content of this first thermally conductive filler (b1) is 7 to 35 volume % of the entire composition. Such a highly dielectric thermally conductive composition can form a cured product in which the thermally conductive filler is filled into the resin. This cured product has electrical insulation and appropriate flexibility and can be used as a thermally conductive member to be placed between the outer periphery of a chuck mechanism of a semiconductor etching apparatus and an edge ring installed on the outer periphery of a substrate to be processed. Furthermore, this cured product becomes a highly dielectric thermally conductive member having both high thermal conductivity and high dielectric properties (hereinafter referred to as high dielectric properties, which means a high relative dielectric constant and a low dielectric dissipation factor tanδ). Even when used as a thermally conductive member to be placed between the outer periphery of an electrostatic chuck on which a substrate to be processed, such as a wafer, is placed and an edge ring installed on the outer periphery of the substrate to be processed in a semiconductor etching apparatus, the difference in relative dielectric constant from other components can be reduced. Furthermore, since a cured product with a high dielectric loss tangent tanδ also generates a large amount of heat due to an electric field, it cannot function satisfactorily as a heat conduction member in an apparatus that generates a high-frequency electric field. However, since the cured product of the highly dielectric thermally conductive composition according to the present invention has a low dielectric loss tangent tanδ, it is suitable for use in semiconductor etching apparatuses and the like that generate a high-frequency electric field.

[0009] The highly dielectric thermally conductive member according to the present invention comprises a cured product of the above-described highly dielectric thermally conductive composition. This highly dielectric thermally conductive member is disposed between an edge ring installed on the outer periphery of a substrate to be processed in a semiconductor etching apparatus and the outer periphery of an electrostatic chuck on which the substrate is mounted. The highly dielectric thermally conductive member has a dielectric constant of 8 or more, a thermal conductivity of 1.0 W / m·K or more, and a dielectric dissipation factor tanδ of 0.01 or less, and the resin (A) is a polyorganosiloxane. The highly dielectric thermally conductive member according to the present invention has a sufficiently high dielectric constant and thermal conductivity, i.e., a dielectric constant of 8 or more, a thermal conductivity of 1.0 W / m·K or more, and a dielectric dissipation factor tanδ of 0.01 or less, and a sufficiently small dielectric dissipation factor tanδ. Therefore, the highly dielectric thermally conductive member according to the present invention is suitable for use as a thermally conductive member disposed between the outer periphery of an electrostatic chuck on which a substrate to be processed, such as a wafer, is mounted, and an edge ring installed on the outer periphery of the substrate to be processed, in a semiconductor etching apparatus where a high-frequency electric field is generated.

[0010] Preferably, in the highly dielectric thermally conductive member according to the present invention, the first thermally conductive filler (b1) has an average particle diameter D ５０ In the highly dielectric thermally conductive member according to the present invention, the average particle diameter D of the first thermally conductive filler (b1) is 0.1 to 100 μm. ５０ The first thermally conductive filler (b1) has an average particle diameter D ５０ It is more preferable that the average particle diameter D of the first thermally conductive filler (b1) is 10 to 40 μm. ５０ In the range of 10 to 40 μm, the volume resistivity and the relative dielectric constant are high. ５０ is the particle diameter D at which the cumulative particle volume from the small particle size side in the volume-based cumulative particle size distribution becomes 50% of the total particle volume. ５０ This means, for example, a value measured by a laser diffraction / scattering method.

[0011] In the highly dielectric thermally conductive member according to the present invention, the first thermally conductive filler (b1) is preferably made of at least one material selected from the group consisting of silicon metal and silicon carbide. By using the first thermally conductive filler (b1) made of such a material, the highly dielectric thermally conductive member according to the present invention can form a thermally conductive sheet having a sufficiently high relative dielectric constant, and is suitable for use in semiconductor etching devices that generate high-frequency electric fields.

[0012] In the highly dielectric thermally conductive member according to the present invention, the thermally conductive filler (B) further has a volume resistivity of 1.0×10 ８The composition preferably contains a second thermally conductive filler (b2) having a resistivity of more than Ω·cm, and the content of the second thermally conductive filler (b2) is 40 to 80 volume % of the entire composition. This second thermally conductive filler (b2) is preferably made of at least one material selected from the group consisting of alumina, aluminum nitride, boron nitride, silicon nitride, diamond, aluminum hydroxide, and magnesium oxide. A high dielectric thermally conductive member that is a cured product of a composition containing such a second thermally conductive filler (b2) can achieve both high thermal conductivity and a high dielectric constant without deteriorating the volume resistivity or hardness. The volume resistivity of the high dielectric thermally conductive member according to the present invention is 1.0 x 10 ９ Preferably, the hardness is Ω·cm or more and Asker C5 to 75 (SRIS 0101 standard, 23±2° C.). By configuring in this way, it can be suitably used in semiconductor etching equipment that generates a high-frequency electric field.

[0013] The semiconductor etching apparatus according to the present invention incorporates the above-described high dielectric thermally conductive member. The above-described high dielectric thermally conductive member has both high thermal conductivity and a high relative dielectric constant, which reduces the difference in relative dielectric constant between components within the etching apparatus, potentially leading to an improvement in yield during etching operations.

[0014] According to the present invention, it is possible to provide a highly dielectric thermally conductive member that has electrical insulation properties, moderate flexibility, and both high thermal conductivity and high dielectric properties, and a highly dielectric thermally conductive composition that can be used to form the same. The highly dielectric thermally conductive member formed from the composition can exhibit sufficient heat dissipation performance even in severe environments where a large amount of heat needs to be dissipated, such as in semiconductor etching equipment that uses high-frequency current.

[0015] 1 is a cross-sectional view showing a semiconductor etching apparatus according to an embodiment of the present invention.

[0016] The highly dielectric thermally conductive composition and the highly dielectric thermally conductive member of the present invention will be described in detail below.

[0017] First, the highly dielectric thermally conductive composition of the present invention will be described. The highly dielectric thermally conductive composition of the present invention contains at least a resin (A) and a thermally conductive filler (B). Each component contained in the highly dielectric thermally conductive composition of the present invention will be described below.

[0018] (Resin (A)) First, the resin (A) will be described. The resin (A) constituting the highly dielectric thermally conductive composition of the present invention is a polymeric material that can be cured by filling with a filler. In the highly dielectric thermally conductive composition of the present invention, the resin (A) is preferably, for example, an epoxy resin, a silicone resin, a phenolic resin, a polyethylene resin, a polypropylene resin, a polyurethane resin, a polyimide resin, or a polyamideimide resin. From the viewpoint of heat resistance and long-term reliability, a silicone resin (polyorganosiloxane) is particularly preferred. The polyorganosiloxane used as the resin (A) can be appropriately selected from various conventionally known and commercially available silicone materials that are commonly used. Therefore, any of heat-curable or room-temperature-curable types, or even UV-curable types, or those with a condensation or addition curing mechanism, can be used. The group bonded to the silicon atom is not particularly limited, and examples thereof include alkyl groups such as methyl, ethyl, and propyl groups, cycloalkyl groups such as cyclopentyl and cyclohexyl groups, alkenyl groups such as vinyl and allyl groups, aryl groups such as phenyl and tolyl groups, and groups in which the hydrogen atoms of these groups are partially substituted with other atoms or bonding groups. In the present invention, the polyorganosiloxane as resin (A) may contain additives such as a crosslinking agent that crosslinks the polyorganosiloxane and a catalyst that promotes curing. For example, in the present invention, a two-component addition-curable polyorganosiloxane resin (CY52-276A / B: manufactured by Dow-Toray Industries, Inc.) is preferably used as the polyorganosiloxane as resin (A). This two-component addition-curable polyorganosiloxane resin is made from raw materials, a polyorganosiloxane having vinyl groups at both ends as the main polymer, a hydrogen polyorganosiloxane as the crosslinking agent, and a platinum catalyst, which are separated into components A and B. By mixing these two components in a predetermined ratio and heating the main polymer and the crosslinking agent in the presence of a platinum catalyst, a crosslinking reaction occurs, and the two-component addition-curable polyorganosiloxane resin can form a cured product.In addition, the polyorganosiloxane as resin (A) can be, for example, a photo- (ultraviolet) curable polyorganosiloxane resin in which a polyorganosiloxane having vinyl groups at both ends as the main polymer and a polyorganosiloxane containing a mercapto group or mercaptoalkyl group as the crosslinking agent undergo a crosslinking reaction under a platinum catalyst, or a moisture-curable polyorganosiloxane resin that undergoes a condensation reaction with moisture to crosslink. In addition, if it is necessary to provide flexibility to the cured product even at low temperatures, it is preferable to use a polyorganosiloxane in which at least a portion of the main polymer is phenyl-modified.

[0019] The content of resin (A) in the highly dielectric thermally conductive composition of the present invention is preferably 12 to 50% by volume, more preferably 15 to 40% by volume, and even more preferably 20 to 35% by volume, relative to the volume of the entire composition, in view of its relationship with the content of thermally conductive filler (B) described below and of curing the composition to form a highly dielectric thermally conductive member having good thermal conductivity, flexibility, and the like.

[0020] (Thermal Conductive Filler (B)) Next, the thermally conductive filler (B) will be described. The thermally conductive filler (B) constituting the highly dielectric thermally conductive composition of the present invention contains at least a first thermally conductive filler (b1). The thermally conductive filler (B) may further contain a second thermally conductive filler (b2). By containing the first thermally conductive filler (b1) and the second thermally conductive filler (b2) in this manner, it is possible to adjust the thermal conductivity, dielectric properties, flexibility, and electrical insulation properties of the cured product of the highly dielectric thermally conductive composition of the present invention.

[0021] The thermally conductive filler (B) in the highly dielectric thermally conductive composition of the present invention is contained in an amount of 50 to 88 volume % of the total composition. By including the thermally conductive filler (B) in the highly dielectric thermally conductive composition, the cured product of the highly dielectric thermally conductive composition of the present invention can achieve high thermal conductivity (high thermal conductivity) and high dielectric properties (high relative dielectric constant, low dielectric dissipation factor), while also achieving moderate flexibility (moderate Asker C) and high electrical insulation (high volume resistivity). From the viewpoint of ensuring these physical properties, the content of the thermally conductive filler (B) is 50 to 88 volume % of the total highly dielectric thermally conductive composition, preferably 60 to 85 volume %, and particularly preferably 65 to 80 volume %. In the present invention, the volume of each filler contained in the thermally conductive filler (B) can be measured, for example, according to the gas displacement method of JIS Z8807:2012, and the contents of the thermally conductive filler (B), the first thermally conductive filler (b1), and the second thermally conductive filler (b2) are determined by calculation from this value and the volume of the entire composition.

[0022] (First Thermally Conductive Filler (b1)) Next, the first thermally conductive filler (b1) constituting the thermally conductive filler (B) will be described. The first thermally conductive filler (b1) is a component for imparting not only thermal conductivity but also high dielectric properties to the cured product of the highly dielectric thermally conductive composition. In the present invention, the first thermally conductive filler (b1) has a volume resistivity of 1.0×10 Ω cm to 1.0×10 ８ It is important that the material has a physical property of Ω cm, and furthermore, the volume resistivity is 1.0×10 ２ Ω・cm~1.0×10 ８It is preferable that the volume resistivity is Ω·cm. Therefore, the first thermally conductive filler (b1) is not particularly limited as long as it is a filler having such a volume resistivity, and known fillers that can be filled into resins, such as inorganic fillers such as metals, metal oxides, metal hydroxides, metal nitrides, metal salts, carbides, and ferrite, and organic fillers such as particles of polymer compounds, can be used. More specifically, examples of the first thermally conductive filler (b1) include silicon carbide (SiC), metal silicon (Si), zinc oxide (ZnO), and magnetite, but from the viewpoint of suitably obtaining a cured product having high thermal conductivity and high dielectric properties, silicon carbide (SiC) and metal silicon (Si) are particularly preferably used. By using a filler having the above-mentioned predetermined volume resistivity, the cured product of the highly dielectric thermally conductive composition according to the present invention has high thermal conductivity (high thermal conductivity), high dielectric properties (high relative permittivity, low dielectric dissipation factor), moderate flexibility (moderate Asker C), and high electrical insulation (high volume resistivity). The first thermally conductive filler (b1) may be a mixture of two or more of the above-mentioned different filler materials. The particle shape of the first thermally conductive filler (b1) is not particularly limited, and may be spherical, flat, irregular, acicular, fibrous, or the like, and can be appropriately selected taking into consideration factors such as fillability into the highly dielectric thermally conductive composition. Furthermore, when the first thermally conductive filler (b1) is a crystalline filler, either a single crystal or a polycrystal may be used.

[0023] Here, the particle diameter of the first thermally conductive filler (b1) can be appropriately selected. For example, the average particle diameter D ５０ Here, from the viewpoint of further improving the relative dielectric constant of the cured product (thermal conductive member) of the highly dielectric thermally conductive composition according to the present invention, the average particle diameter D ５０ is preferably 3 μm to 50 μm, and from the viewpoint of also improving the volume resistivity of the cured product (thermally conductive member), the average particle diameter D ５０It is particularly preferable that the particle size of the first thermally conductive filler (b1) is 10 μm to 40 μm. In addition, in order to improve the filling ability of the first thermally conductive filler (b1) into the resin (A), fillers having different particle sizes may be combined.

[0024] The content of the first thermally conductive filler (b1) in the highly dielectric thermally conductive composition of the present invention is 7% by volume to 35% by volume based on the total composition. By doing so, the cured product of the highly dielectric thermally conductive composition of the present invention can achieve high thermal conductivity and high dielectric properties, as well as moderate flexibility and high electrical insulation. From the viewpoint of further improving these physical properties, the content of the first thermally conductive filler (b1) is 10% by volume to 30% by volume, and more preferably 15% by volume to 20% by volume, based on the total highly dielectric thermally conductive composition.

[0025] (Second Thermally Conductive Filler (b2)) Next, the second thermally conductive filler (b2) will be described. The thermally conductive filler (B) constituting the highly dielectric thermally conductive composition of the present invention contains a second thermally conductive filler (b2). The second thermally conductive filler (b2) is a component for imparting high thermal conductivity and high electrical insulation to the cured product of the highly dielectric thermally conductive composition. In the present invention, the second thermally conductive filler (b2) has a volume resistivity of 1.0×10 ８It has physical properties of more than Ω cm. Therefore, the second thermally conductive filler (b2) is not particularly limited as long as it has such a volume resistivity, and known fillers that can be filled into resins, such as inorganic fillers such as metals, metal oxides, metal hydroxides, metal nitrides, metal salts, carbides, and ferrites, and organic fillers such as particles of polymer compounds, can be used. More specifically, examples of the second thermally conductive filler (b2) include alumina, aluminum nitride, boron nitride, zinc oxide, silicon nitride, diamond, aluminum hydroxide, magnesium oxide, titanium oxide, silicon oxide, mica, soda glass, borosilicate glass, acrylic particles, styrene particles, melamine particles, polyethylene particles, and polyimide particles. In the present invention, alumina, aluminum nitride, boron nitride, silicon nitride, diamond, aluminum hydroxide, and magnesium oxide are particularly suitable as the second thermally conductive filler (b2). The cured product of the highly dielectric thermally conductive composition according to the present invention containing these compounds can achieve high thermal conductivity and high dielectric properties, as well as moderate flexibility and high electrical insulation. The second thermally conductive filler (b2) may be a mixture of two or more of the above-mentioned filler materials having different components.

[0026] The particle diameter of the second thermally conductive filler (b2) can be selected appropriately, but from the viewpoint of improving the filling rate in the highly dielectric thermally conductive composition of the present invention, it is preferable to combine fillers of different particle diameters, such as a large particle diameter component, a medium particle diameter component and a small particle diameter component. For example, the large particle diameter component has an average particle diameter D ５０ is 20 μm to 100 μm, and the medium particle size component has an average particle diameter D ５０ is 1 μm to 20 μm, and the small particle size component has an average particle diameter D ５０ A thickness of 0.01 μm to 1 μm is preferably used.

[0027] In the present invention, the content of the second thermally conductive filler (b2) relative to the entire composition is not particularly limited. However, from the viewpoint of improving the electrical insulation properties of the cured product of the highly dielectric thermally conductive composition of the present invention, it is preferable that the second thermally conductive filler (b2) is contained in a larger amount than the first thermally conductive filler (b1). In the second thermally conductive filler (b2), the mixing ratios of the large particle size component, the medium particle size component, and the small particle size component may be appropriately set. However, since the thermal conductivity of the cured product of the composition of the present invention improves as the large particle size component increases and the filling rate increases, it is preferable to set the mixing ratio so that the large particle size component is increased and the filling rate is high. Furthermore, the mixing ratios of the large particle size component, the medium particle size component, and the small particle size component may be set so that the filling rate of the thermally conductive filler (B) in the highly dielectric thermally conductive composition is increased depending on the content and particle size (average particle size and particle size distribution) of the first thermally conductive filler (b1). In the highly dielectric thermally conductive composition of the present invention, the content of the second thermally conductive filler (b2) is preferably 40 to 80% by volume, and more preferably 45 to 78% by volume, based on the total volume of the composition. By doing so, the cured product of the highly dielectric thermally conductive composition of the present invention can achieve high thermal conductivity and high dielectric properties, as well as moderate flexibility and high electrical insulation.

[0028] (Other Components) The highly dielectric thermally conductive composition of the present invention may contain other components within the scope of not impairing the object of the present invention. For example, various additives can be added to impart functions, such as a dispersant that improves the dispersibility of the thermally conductive filler (B) in the highly dielectric thermally conductive composition components, a reaction inhibitor that adjusts the curing rate, a heat stabilizer, a tackifier that adjusts the adhesion, a pigment or dye for coloring, a flame retardant, and a release agent that improves release from a mold or separator film.

[0029] For example, known dispersants such as silane coupling agents can be used as dispersants, but a single-terminal hydrolyzable polyorganosiloxane in which a hydrolyzable group is bonded to a silicon atom at one end is preferred. By using such a dispersant, in order to increase the mechanical strength of the cured product, even when the thermally conductive filler (B) is blended at a high filling rate, the thermally conductive filler (B) can be well dispersed in the resin (A). Specific examples of single-terminal hydrolyzable polyorganosiloxanes include polyorganosiloxanes containing a single terminal alkoxy group, and polyorganosiloxanes containing a single terminal trimethoxy group and polyorganosiloxanes containing a single terminal triethoxy group are preferred. In addition, in order to maintain the flexibility of the cured product even at low temperatures, the above-mentioned single-terminal hydrolyzable polyorganosiloxane may be phenyl-modified by introducing a phenyl group into the siloxane molecular chain.

[0030] The thermal stabilizer is a component that imparts heat resistance and plasma etching resistance to the cured product of the highly dielectric thermally conductive composition, as well as the effect of reducing the occurrence of oil bleeding. Specific examples of thermal stabilizers include known carbon-based materials such as iron oxide, carbon black, graphite, carbon nanotubes, and carbon fibers, as well as iron carboxylates, cesium hydrate, titania, barium zirconate, cerium octanoate, zirconium octanoate, and porphyrins. However, thermal stabilizers for carbon-based materials that do not act as oxidizers under reduced pressure and heating conditions and have excellent radical trapping properties are preferred. Thermal stabilizers may be used alone or in combination. When resin (A) is a polyorganosiloxane, the blending ratio of the thermal stabilizer is 0.1 to 20 parts by weight, more preferably 5 to 15 parts by weight, and particularly preferably 5 to 10 parts by weight, per 100 parts by weight of resin (A). If the blending ratio of the thermal stabilizer is less than 5 parts by weight, the thermal stabilization effect may not be sufficient in the cured product of the highly dielectric thermally conductive composition, and if it exceeds 20 parts by weight, the thermal conductivity of the highly dielectric thermally conductive composition may decrease or the dispersion of the thermal stabilizer may become insufficient. Note that, when a conductive carbon-based material is used as the thermal stabilizer, it is preferable to blend it in a ratio that does not inhibit the electrical insulation and dielectric properties of the cured product of the highly dielectric thermally conductive composition.

[0031] (Method for Producing Highly Dielectric Thermally Conductive Composition) The highly dielectric thermally conductive composition of the present invention can be easily prepared by blending the above-described (A) and (B) and various other components added as needed in predetermined proportions and uniformly mixing them to form an uncured highly dielectric thermally conductive composition. There are no particular limitations on the mixing means, and known mixers, kneaders, etc. can be used. This highly dielectric thermally conductive composition can be left at room temperature or heated or irradiated with light to promote the crosslinking reaction and form a cured product.

[0032] (Highly Dielectric Thermally Conductive Member) The highly dielectric thermally conductive member according to the present invention comprises a cured product obtained by curing the above-described highly dielectric thermally conductive composition. The cured product of the highly dielectric thermally conductive composition can be obtained by molding the highly dielectric thermally conductive composition into an appropriate shape, such as a bulk or sheet, and leaving it at room temperature, or by heating or irradiating it with light to promote the crosslinking reaction. Known methods, such as mold molding and calendar molding, may be used to mold the highly dielectric thermally conductive composition. When molding the cured product of the highly dielectric thermally conductive composition into a bulk form, mold molding is preferred. In particular, when the resin (A) is a thermoplastic resin, mold molding of the highly dielectric thermally conductive composition is preferably performed by hot molding or injection molding. When the resin (A) is a thermosetting resin or a photocurable resin, mold molding, LIM molding, or the like is preferred. When molding the cured product of the highly dielectric thermally conductive composition into a sheet form, calendar molding is preferred.

[0033] As described above, the highly dielectric thermally conductive member according to the present invention is obtained from a cured product of a highly dielectric thermally conductive composition. Because of its excellent thermal stability, polyorganosiloxane is preferably used as the resin (A) constituting the highly dielectric thermally conductive composition. This highly dielectric thermally conductive member has a relative dielectric constant of 8 or more, a thermal conductivity of 1.0 W / m·K or more, and a dielectric loss tangent tanδ of 0.01 or less. The relative dielectric constant and dielectric loss tangent tanδ can be set within the above ranges to match the dielectric characteristics of the electrostatic chuck device and its surroundings in the semiconductor etching apparatus to which it is applied. Because such a highly dielectric thermally conductive member has a sufficiently small dielectric loss tangent tanδ, it is less likely to generate heat even in semiconductor etching apparatuses that generate high-frequency electric fields, as described below, and is therefore suitable for use in such apparatuses. Furthermore, from the viewpoint of approximating the relative dielectric constant of other components used in the semiconductor etching apparatus, the highly dielectric thermally conductive member of the present invention preferably has a relative dielectric constant of 10 or more, and more preferably 10 to 20. Furthermore, from the viewpoint of efficiently dissipating heat from the focus ring by disposing the highly dielectric heat-conductive member according to the present invention between the mounting table and the focus ring of a semiconductor etching apparatus in which a high-frequency electric field is generated, it is preferable that the highly dielectric heat-conductive member have a higher thermal conductivity, and more specifically, a thermal conductivity of 5.0 W / m·K or more is more preferable. Furthermore, from the viewpoint of mounting the highly dielectric heat-conductive member according to the present invention in semiconductor etching apparatus 100 in which a high-frequency electric field is generated, the electrical insulation of the highly dielectric heat-conductive member according to the present invention is such that the volume resistivity is 1.0×10 ９ The hardness is preferably Ω·cm or more, and the flexibility is preferably Asker C5 to 75 (SRIS 0101 standard, 23±2° C.), and particularly preferably Asker C15 to 65.

[0034] The shape of the highly dielectric thermally conductive member according to the present invention is not particularly limited, and may be formed into a bulk shape, a sheet shape, or the like, depending on the application, but when it is used to be placed between adjacent components to improve heat transfer between the components, it is preferably formed into a sheet shape. When the highly dielectric thermally conductive member is placed between components to transfer heat between the components, the thickness direction of the sheet-like highly dielectric thermally conductive member is the main direction of heat conduction, so from the viewpoint of reducing thermal resistance, a thin thickness is preferable, specifically 1 mm or less is preferable, 0.5 mm or less is more preferable, and 0.1 mm or less is even more preferable.

[0035] The planar shape of the highly dielectric thermally conductive member according to the present invention may be appropriately set depending on the intended use and the shape of the device, such as circular, rectangular, irregular, etc. When the highly dielectric thermally conductive member is in sheet form, an uncured composition is supplied onto a substrate film, formed into a sheet by a known method such as calendar molding, and cured. After this, the sheet-shaped cured product can be formed into a desired shape using a known method such as punching, laser processing, or plotter processing.

[0036] Furthermore, the surface of the highly dielectric thermally conductive member according to the present invention may be smooth, but preferably has fine irregularities. Generally, when a thermally conductive member is placed between the mounting table and the focus ring of a semiconductor etching apparatus, the presence of air bubbles between the mounting table and the highly dielectric thermally conductive member, or between the focus ring and the highly dielectric thermally conductive member, increases thermal resistance and impedes heat transfer from the focus ring to the mounting table. However, by forming fine irregularities on the surface of the highly dielectric thermally conductive member according to the present invention that do not affect adhesion, such air bubbles can be easily removed. The fine irregularities on the surface of the highly dielectric thermally conductive member preferably have a step height between the highest point of the convex portion and the lowest point of the concave portion on the sheet surface of 10 μm to 100 μm, and the convex portions account for 50% to 95% of the sheet surface area. The shape of the irregularity pattern can be appropriately determined, but a grid-like groove is preferred because it is easier to avoid residual air bubbles.

[0037] The surface of the highly dielectric thermally conductive member according to the present invention may be non-adhesive or may be made adhesive. From the viewpoint of ease of attachment and detachment to and from the mounting table or focus ring of a semiconductor etching apparatus, the surface of the highly dielectric thermally conductive member that contacts the mounting table and the surface that contacts the focus ring may have different adhesivenesses. Adhesion can be imparted to the surface of the highly dielectric thermally conductive member by applying an adhesive silicone resin as the resin (A). Adhesion can also be imparted by other known methods, such as adding a tackifier to the highly dielectric thermally conductive composition of the present invention or by coating the surface with an adhesive material after curing the highly dielectric thermally conductive composition of the present invention. Furthermore, the surface of the highly dielectric thermally conductive member can be made non-sticky by using a non-sticky silicone resin as the resin (A). However, the surface of the highly dielectric thermally conductive member can also be made non-sticky by other known methods, such as applying a non-stick coating to the surface after curing the highly dielectric thermally conductive composition of the present invention, or by performing surface modification such as excimer treatment or plasma treatment.

[0038] (Semiconductor etching apparatus) Next, a semiconductor etching apparatus in which the highly dielectric thermally conductive member of the present invention is mounted will be described together with the highly dielectric thermally conductive member of the present invention. The highly dielectric thermally conductive member of the present invention is a highly dielectric thermally conductive member made of a cured product of a highly dielectric thermally conductive composition, and is mounted in semiconductor etching apparatus 100.

[0039] As shown in FIG. 1 , a highly dielectric thermally conductive member 5 according to the present invention is mounted on a substrate mounting unit 1 of a semiconductor etching apparatus 100. The substrate mounting unit 1 includes a mounting table 2 (hereinafter also referred to as a lower electrode unit 2) including a chuck mechanism 2a for mounting and fixing a wafer W thereon by electrostatic chucking or the like and a support table 2b functioning as a lower electrode, a focus ring 3 disposed on the outer periphery of the mounting table 2, and a cooling unit 4. The highly dielectric thermally conductive member 5 according to the present invention is disposed between the mounting table 2 and the focus ring 3. During etching, the temperature of the wafer W needs to be adjusted to an optimal condition, and the mounting table 2 is cooled by the cooling unit 4 to prevent the temperature of the wafer W from rising too much due to plasma.

[0040] In this semiconductor etching apparatus 100, the etching process on the wafer W is performed by placing the wafer W on the substrate mounting unit 1 in the processing chamber and irradiating it with plasma or the like. More specifically, the etching process on the wafer W begins by placing the wafer W on the mounting table 2, fixing the wafer W with a chuck mechanism 2a such as an electrostatic chuck while maintaining the processing chamber at a predetermined vacuum level, and applying a high-frequency voltage between the lower electrode unit 2 and an upper electrode (not shown) disposed opposite the lower electrode unit 2 to generate plasma in the processing chamber and etch the surface of the wafer W. The focus ring 3 is disposed to surround the wafer W, thereby reducing discontinuities in the plasma near the peripheral edge of the wafer W and enabling more uniform plasma processing of the entire surface of the wafer W.

[0041] As described above, the high dielectric thermally conductive member according to the present invention has a thermal conductivity of 1.0 W / m·K or greater. During etching processing using semiconductor etching apparatus 100, focus ring 3 is also irradiated with plasma and its temperature rises. This increases the temperature of the peripheral edge of wafer W compared to the central region of wafer W, potentially resulting in poor etching characteristics. However, by disposing high dielectric thermally conductive member 5 according to the present invention between mounting table 2 and focus ring 3, heat is transferred from focus ring 3 to mounting table 2 via high dielectric thermally conductive member 5, thereby preventing focus ring 3 from becoming too hot. Furthermore, while semiconductor etching apparatus 100 uses many components with high dielectric constants, including chuck mechanism 2 a, high dielectric thermally conductive member 5 according to the present invention has a dielectric constant of 8 or greater. This reduces the difference in dielectric constant between components within semiconductor etching apparatus 100, which is expected to improve yield during etching operations. Furthermore, the highly dielectric thermally conductive member 5 according to the present invention has a sufficiently small dielectric loss tangent tanδ of 0.01 or less, and therefore does not generate much heat even in an environment where a high-frequency electric field is generated, making it suitable for use in the semiconductor etching apparatus 100.

[0042] The present invention will be specifically described below with reference to examples, but the present invention is not particularly limited to these examples.

[0043] The methods for measuring physical properties in the examples and comparative examples are as follows.

[0044] (1) Thermal Conductivity (Thermal Conductivity) To evaluate thermal conductivity, two bulk cured products measuring 25 mm x 25 mm x 10 mm were prepared as a pair of samples. The thermal conductivity of the bulk cured products was measured using a 3.189 mm diameter Kapton 5465F1 sensor and the bulk TYPE 1 measurement mode of a thermal property measuring device (Hot Disk AB TPS2500S) in accordance with ISO 22007-2 by the hot disk method. The thermal conductivity of the cured products was evaluated as particularly high quality (pass) if it was over 5 W / m K, as passed (○) if it was between 1 W / m K and 5 W / m K, and as failed (×) if it was less than 1 W / m K.

[0045] (2) Relative permittivity (dielectric properties) For the evaluation of dielectric properties, a sheet-like cured product measuring 90 mm x 90 mm x 0.5 mm thick was prepared, and the relative permittivity of the sheet-like cured product was measured using a dielectric property measuring device (PRECISION COMPONENT ANALYZER 6440B manufactured by Wayne Kerr Co.) in accordance with JIS C 2138. The relative permittivity of the cured product was evaluated as follows: a value of 10 or more was rated as pass (◎), indicating particularly high quality; a value of 8 or more but less than 10 was rated as pass (◯); and a value of less than 8 was rated as fail (×).

[0046] (3) Dielectric Loss Tangent (Dielectric Properties) A ​​sheet-like cured product measuring 90 mm x 90 mm x 0.5 mm thick was prepared, and the dielectric loss tangent of the sheet-like cured product was measured in accordance with JIS C 2138 using a dielectric property measuring device (Precision Component Analyzer 6440B manufactured by Wayne Kerr Co.) The dielectric loss tangent of the cured product was evaluated as pass (◎) when it was 0.01 or less, and as fail (×) when it was more than 0.01.

[0047] (4) Volume Resistivity (Electrical Insulation) A sheet-like cured product measuring 50 mm x 50 mm x 0.5 mm thick was prepared, and the volume resistivity of the sheet-like cured product was measured in accordance with JIS K6911 using a volume resistivity measuring device (Hiresta UP MCP-HT450 manufactured by Nitto Seiko Analytic Co., Ltd.). The electrical insulation of the cured product was evaluated when the volume resistivity was 1.0 x 10 １１ Those with a resistance of Ω cm or more are considered to be of particularly high quality and are considered to be pass (◎), and those with a resistance of 1.0 × 10 １０ Ω・cm or more 1.0×10 １１ Those with a resistance of less than Ω cm were considered to be pass (○), and those with a resistance of less than 1.0 × 10 １０ Those with a resistance of less than Ω·cm were rated as unacceptable (×).

[0048] (5) Hardness (Asker C) (Flexibility) A bulk cured product measuring 50 mm x 50 mm x 10 mm thick was prepared, and the hardness (Asker C) of the sheet-like cured product was measured in accordance with JIS K 7312 using a hardness measuring device (Asker Rubber Hardness Meter Type C, manufactured by Kobunshi Keiki Co., Ltd.) The flexibility of the cured product was evaluated as follows: a hardness (Asker C) of 15 or more and 65 or less was rated as particularly high quality, passing (◎); a hardness of more than 65 and 75 or less or less than 15 was rated as passing (◯); and a hardness of more than 75 was rated as failing (×).

[0049] The names, physical properties, etc. of the components of the raw materials used in the following Examples and Comparative Examples are shown below.

[0050] (Resin (A)) As the resin (A), a two-component addition type thermosetting polyorganosiloxane (DOW SIL CY52-276, manufactured by Dow Toray Industries, Inc.) was used.

[0051] Thermally conductive filler (B) The materials shown in Table 1 were used as the first thermally conductive filler (b1).

[0052]

[0053] As the second thermally conductive filler (b2), a material obtained by mixing the materials shown in Table 2 in the amounts shown in Table 3 was used.

[0054]

[0055]

[0056] (Preparation of Samples) Compositions according to Examples and Comparative Examples were prepared and cured products of each were prepared according to the following procedures.

[0057] The material for the first thermally conductive filler (b1) shown in Table 1 and the material for the second thermally conductive filler (b2) shown in Table 3 were added to resin (A), mixed for 2 minutes using a tabletop mixer (Thinky Corporation, Awatori Rentaro), and then vacuum degassed for 5 minutes to obtain an uncured composition. The compositions obtained by varying the amount of the first thermally conductive filler (b1) and the second thermally conductive filler (b2) per 100 g of resin (A) were designated the high dielectric thermally conductive compositions of Examples 1 to 18 and the compositions of Comparative Examples 1 to 5, respectively. The amounts of each component in Examples 1 to 18 and Comparative Examples 1 to 5 are shown in Tables 4 to 7. The contents (volume %) of the first thermally conductive filler (b1) and the second thermally conductive filler (b2) shown in Tables 4 to 7 are values ​​obtained by measuring the volume of each filler at each blend amount according to the gas displacement method of JIS Z8807:2012 before mixing with the resin (A), and then calculating the content (volume %) of each filler relative to the volume of the entire composition after mixing.

[0058] Next, the highly dielectric thermally conductive compositions of Examples 1 to 18 and the compositions of Comparative Examples 1 to 5 were each cast into a mold, preheated in an air atmosphere in a hot air oven (WFO-520W, manufactured by Tokyo Rikakikai Co., Ltd.) at 70°C for 1 hour, and then heated at 100°C for 3 hours to cure, thereby obtaining samples for evaluation of the above-mentioned (1) thermal conductivity and (5) hardness.

[0059] Next, each of the highly dielectric thermally conductive compositions of Examples 1 to 18 and the compositions of Comparative Examples 1 to 5 was sandwiched between a pair of PET films and calendered to a predetermined thickness. The resulting compositions were then preheated at 70°C for 1 hour in an air atmosphere in a hot air oven (WFO-520W manufactured by Tokyo Rikakikai Co., Ltd.), and then cured by heating at 100°C for 3 hours. The resulting compositions were then punched into a predetermined shape to obtain samples for evaluation of the above-mentioned (2) relative dielectric constant, (3) dielectric loss tangent, and (4) volume resistivity.

[0060]

[0061]

[0062]

[0063]

[0064] As shown in Table 5, from the results of Comparative Example 1, when the thermally conductive filler (B) contained together with at least the resin (A) constituting the composition was 40% by volume or less relative to the entire composition, the thermal conductivity was as low as 0.9, which was insufficient thermal conductivity, and the volume resistivity was 8.946 × 10 ４ It was revealed that the dielectric constant was as low as Ω·cm, and the conductivity was too high, making it unsuitable for use in devices that use high frequencies, such as semiconductor etching devices. From the results of Comparative Example 3, it was revealed that when the thermally conductive filler (B) contained together with at least the resin (A) constituting the composition was 90% by volume or more relative to the entire composition, the Asker C was as high as 88.2, resulting in insufficient flexibility and strength, making it unsuitable for use in semiconductor etching devices, etc. In contrast, as shown in Tables 4 to 7, the results of Examples 1 to 18 (particularly Examples 2, 7, and 8) indicate that the highly dielectric thermally conductive composition of the present invention contains at least 50% by volume to 85% by volume of the thermally conductive filler (B) relative to the entire composition, and the cured product of the highly dielectric thermally conductive composition of the present invention has high dielectric properties (relative permittivity of 8 or more, dielectric dissipation factor of 0.01 or less) and moderate flexibility (Asker C of 5 to 75), as well as high thermal conductivity (thermal conductivity of 1 W / m·K or more), and electrical insulation with a volume resistivity of 1.0×10 １０ It was found that the resistivity was Ω·cm or more, making it suitable for use in semiconductor etching equipment and the like.

[0065] Furthermore, as shown in Table 6, from the results of Comparative Example 5, the first thermally conductive filler (b1) constituting the thermally conductive filler (B) had a volume resistivity of 1.0 × 10 14 In the case of alumina with a dielectric constant of Ω cm, the relative dielectric constant of the sheet sample was less than 8, and therefore the difference in relative dielectric constant between the sheet sample and other components commonly installed in semiconductor etching equipment was found to be too large. Furthermore, from the results of Comparative Example 4, it was found that the first thermally conductive filler (b1) had a volume resistivity of 1.0 × 10 －２ In the case of carbon fibers with a dielectric constant of Ω cm, the dielectric loss tangent tanδ of the sheet sample exceeds 0.01, so that the sheet sample is prone to heat generation and the volume resistivity of the sheet sample is 1.0 × 10 １０Since the resistivity was less than Ω cm, the electrical insulation was insufficient and it was found that the composition was not suitable for use in a semiconductor etching apparatus, etc. In contrast, as shown in Tables 4 to 7, in Examples 1 to 8 and 10 to 18, the volume resistivity of the first thermally conductive filler (b1) constituting the thermally conductive filler (B) was 0.53 × 10 ６ In Example 9, the volume resistivity of the first thermally conductive filler (b1) constituting the thermally conductive filler (B) is 1.4 × 10 １ The dielectric constant of the first thermally conductive filler (b1) was 1.4×10 Ω cm, and the dielectric loss tangent tanδ was small, making it difficult to generate heat. The volume resistivity was high, and the electrical insulation was sufficient. From the results of Examples 1 to 18, it was found that the volume resistivity of at least the first thermally conductive filler (b1) was 1.4×10 １ Ω・cm or more, 0.53×10 ６ Ω cm or less, the cured product of the highly dielectric thermally conductive composition according to the present invention has a dielectric loss tangent tanδ of 0.01 or less and a volume resistivity of 1.0 × 10 １０ The dielectric constant of the thermally conductive filler (B) is 8 or more, and the dielectric constant of the thermally conductive filler (B) is 8 or more. The difference in dielectric constant between the thermally conductive filler (B) and the components mounted on the thermally conductive filler (B) is small, and the thermally conductive filler (B) is suitable for use in high-frequency devices such as semiconductor etching equipment.

[0066] As shown in Table 7, in the highly dielectric thermally conductive compositions of the present invention according to Examples 10 to 16, the first thermally conductive filler (b1) has different average particle diameters D ５０ The cured products of the highly dielectric thermally conductive compositions of the present invention according to Examples 10 to 16 passed all of the above-mentioned physical property evaluations, and therefore the highly dielectric thermally conductive compositions of the present invention have the same structure except for the average particle diameter D of the first thermally conductive filler (b1). ５０ It was found that the average particle diameter D of the first thermally conductive filler (b1) is preferably at least 0.5 μm or more and 58.6 μm or less. ５０It has been found that the larger the average particle diameter D of the first thermally conductive filler (b1), the lower the volume resistivity of the cured product of the highly dielectric thermally conductive composition of the present invention. ５０ In Example 16, the volume resistivity of the cured product was 0.99 × 10 11 Ω cm, which is acceptable but low, whereas the average particle diameter D ５０ In Example 15, the volume resistivity of the cured product was 1.18 × 10 １１ In Examples 10 to 16, the average particle diameter D of the first thermally conductive filler (b1) was ５０ Example 13, in which the average particle diameter D ５０ As the thickness of the cured product increased from 30.9 μm, the dielectric constant of the cured product generally tended to decrease.

[0067] Furthermore, from the results of Examples 1 to 18, it was found that the highly dielectric thermally conductive composition according to the present invention had a volume resistivity of 1×10 ８ It was confirmed that the second thermally conductive filler (b2) having a resistivity of Ω·cm or more may be contained in an amount of 40 to 75% by volume.

[0068] Furthermore, the highly dielectric thermally conductive compositions of the present invention according to Examples 17 and 18 differed from Example 13 only in the components of the second thermally conductive filler (b2), and the content of the second thermally conductive filler (b2) relative to the entire composition was the same. Since the cured products of the highly dielectric thermally conductive compositions of the present invention according to Examples 17 and 18 passed all of the above-mentioned physical property evaluations, it was confirmed that the second thermally conductive filler (b2) may be at least aluminum nitride (AlN) or magnesium oxide (MgO) in addition to alumina.

[0069] The present invention is not limited to the above-described embodiments or examples, and various modified design forms are also included in the technical scope within the scope that does not deviate from the gist of the invention described in the claims.

[0070] The highly dielectric thermally conductive composition of the present invention has electrical insulation properties and moderate flexibility, as well as high thermal conductivity and high dielectric properties, and is therefore useful as a material for components of devices that utilize high frequency current, and is widely useful in industries such as electronic devices and semiconductor devices.

[0071] REFERENCE SIGNS LIST 1 Substrate mounting unit 2 Mounting table (lower electrode unit) 2a Chuck mechanism (wafer chuck, etc.) 2b Support table 3 Focus ring (edge ​​ring) 4 Cooling unit 5 Heat conduction member W Substrate to be processed (wafer, etc.) 100 Semiconductor etching apparatus

Claims

1. A highly dielectric thermally conductive composition containing a resin (A) and a thermally conductive filler (B), wherein the content of the thermally conductive filler (B) is 50 to 88% by volume of the entire composition, and the thermally conductive filler (B) has a volume resistivity of 1.0 x 10 to 1.0 x 10. ８ A highly dielectric thermally conductive composition comprising a first thermally conductive filler (b1) having a dielectric constant of 0.01% Ω cm, and a content of the first thermally conductive filler (b1) in the entire composition is 7 to 35 volume %.

2. A highly dielectric heat-conductive member made from a cured product of the highly dielectric heat-conductive composition according to claim 1, which is disposed between an edge ring installed on the outer periphery of a substrate to be processed in a semiconductor etching device and the outer periphery of an electrostatic chuck on which the substrate to be processed is placed, and which has a relative dielectric constant of 8 or more, a thermal conductivity of 1.0 W / m·K or more, and a dielectric loss tangent tanδ of 0.01 or less, and the resin (A) is polyorganosiloxane.

3. The first thermally conductive filler (b1) has an average particle diameter D ５０ 3. The highly dielectric thermally conductive member according to claim 2, wherein the thickness is 0.1 to 100 μm.

4. The first thermally conductive filler (b1) has an average particle diameter D ５０ 4. The highly dielectric thermally conductive member according to claim 2, wherein the thickness is 10 to 40 μm.

5. A highly dielectric thermally conductive member according to any one of claims 2 to 4, characterized in that the first thermally conductive filler (b1) is made of at least one material selected from the group consisting of silicon metal and silicon carbide.

6. The thermally conductive filler (B) further has a volume resistivity of 1.0×10 ８ The highly dielectric thermally conductive member according to any one of claims 2 to 5, further comprising a second thermally conductive filler (b2) having a dielectric constant of more than Ω cm, wherein the content of the second thermally conductive filler (b2) is 40 to 80 volume % of the entire composition.

7. A highly dielectric thermally conductive member as described in claim 6, characterized in that the second thermally conductive filler (b2) is made of at least one material selected from the group consisting of alumina, aluminum nitride, boron nitride, silicon nitride, diamond, aluminum hydroxide, and magnesium oxide.

8. Volume resistivity is 1.0 x 10 ９ 8. The highly dielectric heat-conductive member according to claim 2, wherein the dielectric constant is Ω·cm or more.

9. A highly dielectric heat-conductive member according to any one of claims 2 to 8, characterized in that the hardness is Asker C5 to C75 (SRIS 0101 standard, 23±2°C).

10. A semiconductor etching device incorporating the highly dielectric and thermally conductive member according to any one of claims 2 to 9.

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