Thermally conductive silicone resin composition and thermally conductive member

Abstract

Provided is a thermally conductive silicone resin composition which is capable of forming a cured product having both flexibility under low-temperature conditions and high thermal conductivity even when highly filled with a thermally conductive filler. This thermally conductive silicone resin composition contains a silicone resin component, a thermally conductive filler (C), and a surface treatment agent (D) for treating the surface of the thermally conductive filler (C). The silicone resin component contains a polyorganosiloxane (A) having alkenyl groups at least at both ends, a hydrogen polyorganosiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (E), and component (A) is a phenyl-modified polyorganosiloxane having at least one phenyl group in the molecule. Component (B) is a phenyl-modified hydrogen polyorganosiloxane having at least one phenyl group in the molecule, the blending proportion of component (C) is 300-2200 parts by weight per 100 parts by weight of the silicone resin component, component (D) is a single-terminal hydrolyzable polyorganosiloxane having a hydrolyzable group bonded to a silicon atom at a single terminal, and the blending proportion of component (C) is 300-2200 parts by weight per 100 parts by weight of component (C). The blending ratio of the component (D) is 0.5-2 parts by weight, and the low-temperature change rate of the complex elastic modulus of a cured product of the thermally conductive silicone resin composition, obtained by dividing the absolute value of the difference between the complex elastic moduli at 20 DEG C and-80 DEG C by the complex elastic modulus at 20 DEG C, is 1000% or less.

Description

Technical Field

[0001] The present invention mainly relates to a thermally conductive silicone resin composition used in a thermally conductive member for suppressing the temperature rise of a substrate being etched in a semiconductor etching apparatus. More specifically, the present invention relates to a thermally conductive silicone resin composition used in a thermally conductive member sandwiched between a focus ring and a mounting table provided on the periphery of the substrate being processed, and which can achieve stable adhesion to an adherend even in low-temperature regions. Background Art

[0002] In the semiconductor manufacturing process using dry etching, Figure 1 As shown, a substrate W to be processed, such as a wafer, is placed on a substrate mounting unit 1 in a processing chamber and irradiated with plasma of an etching gas, thereby performing a predetermined etching process on the substrate to be processed. The substrate mounting unit 1 includes: a mounting table 2 (also referred to as a lower electrode unit 2), which includes a chuck mechanism 2a for mounting the wafer W and fixing it by means of an electrostatic chuck, and a support table 2b serving as a lower electrode; and a focus ring 3 (also referred to as an edge ring) disposed on the outer periphery of the mounting table 2. The mounting table 2 is cooled by a cooling unit 4 to adjust the temperature of the wafer W and the focus ring 3 during the etching process to optimal conditions. It should be noted that there is also a structure in which the focus ring 3 is disposed on the mounting table 2 via other accessories, but in this application, the structure in which the accessories are mounted on the mounting table is also collectively referred to as the mounting table 2.

[0003] The etching process of the wafer is as follows: after placing the wafer W on the lower electrode unit 2 which serves as a loading table, the wafer W is fixed by a suction cup mechanism 2a such as an electrostatic suction cup while maintaining a predetermined vacuum level in the processing chamber, and a high-frequency voltage is applied between the upper electrode (not shown) arranged opposite to the lower electrode unit 2 and the lower electrode unit 2, thereby generating a plasma of etching gas in the processing chamber and etching the surface of the wafer W.

[0004] During this plasma etching process, the focus ring 3 serves to mitigate plasma discontinuities near the periphery of the wafer W, ensuring uniform plasma processing across the entire surface of the wafer W. During plasma etching, the wafer W is cooled by adjusting the mounting table 2 to a low temperature to suppress increases in wafer temperature. However, as the temperature of the focus ring 3, which is exposed to plasma, rises, the periphery of the wafer W in contact with the focus ring 3 becomes hotter than the center of the wafer W. This can lead to deteriorated etching characteristics at the periphery of the wafer W, resulting in problems such as reduced hole-boring performance (the ability to reliably etch to a predetermined depth) and a decreased aspect ratio.

[0005] As one of the measures to prevent the temperature of the focus ring 3 from rising, Figure 2As shown, a method has been proposed in which a heat transfer member 5 is interposed between the mounting table 2 and the focus ring 3, transferring heat from the focus ring 3 to the mounting table 2 via the heat transfer member 5. For example, Patent Document 1 discloses a mounting device for a workpiece, wherein a heat transfer medium is interposed between the mounting table and the focus ring and a pressing mechanism is provided for pressing and securing the focus ring to the mounting table. Furthermore, Patent Document 2 proposes a method in which a heat transfer sheet is placed between the focus ring and the mounting table. Prior to processing the substrate, the chamber is evacuated and then returned to atmospheric pressure or a slightly reduced pressure. This removes air from the gap between the heat transfer sheet and the mounting surface, ensuring close contact between the heat transfer sheet and the mounting surface and improving heat conduction through the focus ring.

[0006] On the other hand, in recent years, semiconductor designs have gradually shifted to designs that achieve large capacity through multilayered structures, such as three-dimensional NAND flash memories (3D-NAND). In order to etch wafers deeper than before, plasma etching has been increasingly driven by higher power. When etching using high-power plasma, the wafer and focus ring become hotter due to the heat of the plasma than in conventional etching processes under plasma conditions. Therefore, the temperature of the stage must be set to a lower temperature than before to cool the wafer, while also cooling the focus ring via a heat-conducting member. Therefore, for example, Patent Document 3 proposes an etching method comprising: cooling the surface temperature of a substrate to below -40°C; generating a plasma containing a gas containing hydrogen and fluorine using high-frequency power using plasma generation; and etching the aforementioned stacked film using the generated plasma.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2002-16126

[0010] Patent Document 2: Japanese Patent No. 4695606

[0011] Patent Document 3: Japanese Patent Application Laid-Open No. 2022-36899

[0012] Patent Document 4: Japanese Patent No. 2623380 Summary of the Invention

[0013] Problems to be solved by the invention

[0014] However, due to this further reduction in the cooling conditions for the stage, the heat conduction member is used under conditions where the temperature difference between the side in close contact with the focus ring exposed to plasma and the side in close contact with the stage is significantly greater than before. Consequently, stress is generated in the heat conduction member due to the thermal expansion difference between the two sides. If the surface of the heat conduction member in contact with the stage hardens under the harsh low-temperature conditions, it can easily peel off from the stage, and its adhesion to the stage is likely to be reduced compared to before. Furthermore, if adhesion with the stage is reduced, the contact area between the stage and the heat conduction member decreases, increasing thermal resistance. This increases the risk of adversely affecting the cooling performance of the focus ring.

[0015] As a method for improving this problem, it is effective to use a heat-conducting member that is flexible even under low-temperature conditions. For example, Patent Document 4 discloses a gel-cured material formed from a silicone composition. The silicone composition contains: an organopolysiloxane (A) having siloxane units having phenyl and vinyl groups in its skeleton; a hydrogen polysiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule; a platinum group metal catalyst (C); and an alumina powder (D) that is a substantially spherical powder with an average particle size of 50 μm or less, and the content of alkali metal ions and halogen ions extracted for 20 hours in an atmosphere at 121°C, 2 atmospheres, and 100% RH is each 5 ppm or less.

[0016] Meanwhile, thermally conductive components are increasingly being developed with higher thermal conductive filler content to enhance thermal conductivity. This increased thermal conductive filler content reduces its dispersibility within the resin matrix. Therefore, higher content is achieved by adding a surface treatment agent that modifies the surface of the thermally conductive filler to improve its dispersibility. The amount of surface treatment agent added is determined based on the amount of thermally conductive filler. Therefore, as the thermal conductive filler content increases due to higher content, the amount of surface treatment agent added increases, while the proportion of the silicone resin component in the resin matrix decreases. Consequently, the proportion of the surface treatment agent added relative to the amount of the silicone resin component increases.

[0017] Therefore, even if a silicone composition can form a gel-cured product with improved flexibility at low temperatures as in Patent Document 4, if the amount of thermally conductive filler and surface treatment agent added to the silicone composition is increased to further improve thermal conductivity, there is still the problem of loss of flexibility at low temperatures.

[0018] Therefore, the present invention aims to solve the above-mentioned problems of the prior art and has an object to provide a thermally conductive silicone resin composition that can form a cured product having both flexibility under low temperature conditions and high thermal conductivity even when highly filled with a thermally conductive filler.

[0019] Furthermore, a second object of the present invention is to provide a heat conduction member or a heat conduction member for a semiconductor etching apparatus that solves the above-mentioned problem.

[0020] Methods for solving problems

[0021] In order to solve the above-mentioned problems, the thermally conductive silicone resin composition of the present invention comprises a silicone resin component, a thermally conductive filler (C), and a surface treatment agent (D) for surface-treating the thermally conductive filler (C). The silicone resin component contains a polyorganosiloxane (A) having alkenyl groups at at least both ends, a hydrogen polyorganosiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (E), wherein the component (A) is a phenyl-modified polyorganosiloxane having at least one phenyl group in one molecule, and the component (B) is a phenyl-modified hydrogen polyorganosiloxane having at least one phenyl group in one molecule. The present invention relates to a thermally conductive silicone resin composition comprising a heat-conductive ...

[0022] Both the polyorganosiloxane (A) and hydrogenpolyorganosiloxane (B) that constitute the silicone resin component are phenyl-modified. Therefore, due to the steric hindrance of the phenyl groups, it is believed that solidification is difficult even at low temperatures, and the cured product formed from this thermally conductive silicone resin composition can maintain its flexibility at low temperatures. Here, solidification refers to a state in which, under low-temperature conditions, the thermal vibration of the molecular chains decreases, the influence of intermolecular forces increases, the molecular chains align and crystallize, and the liquid loses its fluidity, while the cured product loses its flexibility. Furthermore, it is believed that by setting the blending ratio of the thermally conductive filler (C) to 300 to 2200 parts by weight relative to 100 parts by weight of the silicone resin component and including 0.5 to 2 parts by weight of a mono-terminal hydrolyzable polyorganosiloxane relative to 100 parts by weight of the thermally conductive filler (C) as a surface treatment agent (D) for modifying the surface of the thermally conductive filler (C), the dispersibility of the thermally conductive filler (C) in the silicone resin component is improved, achieving a uniform dispersion state and high filling. Furthermore, it is believed that solidification of the thermally conductive filler (C) at the surface treatment interface in the thermally conductive silicone resin composition is suppressed under low temperature conditions. As a result, even when the thermally conductive filler filling ratio is designed to be high, the flexibility of the cured thermally conductive silicone resin composition can be maintained under low temperature conditions, thereby achieving close adhesion to the surface of the adherend. In addition, the low-temperature change rate of the complex elastic modulus, which is calculated by dividing the absolute value of the difference between the complex elastic modulus at 20°C and at -80°C after curing by the complex elastic modulus at 20°C, is set to less than 1000%. Thus, even when used under low-temperature conditions after curing, the softness is maintained and the adhesion to adherends such as cooling bodies and heating bodies is maintained, thereby stably performing the function as a heat conduction medium.

[0023] In the thermally conductive silicone resin composition of the present invention, the hydrolyzable group in the mono-terminal hydrolyzable polyorganosiloxane as component (D) of the surface treatment agent is preferably an alkoxy group. This effectively suppresses coagulation under low-temperature conditions, improving the effect of maintaining flexibility when the cured product is used under low-temperature conditions. Furthermore, the dispersibility of the thermally conductive filler (C) in the silicone resin component is further improved, achieving a uniform dispersion and high filling.

[0024] The one-terminal hydrolyzable polyorganosiloxane constituting the component (D) of the thermally conductive silicone resin composition of the present invention is preferably a polyorganosiloxane containing a trialkoxysilyl group at one terminal.

[0025] Furthermore, the one-terminal hydrolyzable polyorganosiloxane constituting component (D) of the thermally conductive silicone resin composition of the present invention preferably has a phenyl group bonded to the polysiloxane chain. This effectively suppresses the solidification of the surface-treated layer formed on the surface of the thermally conductive filler (C) by the surface-treating agent (D) under low-temperature conditions, thereby further enhancing the effect of maintaining flexibility when the cured product is used under low-temperature conditions.

[0026] Furthermore, the one-terminal hydrolyzable polyorganosiloxane constituting component (D) of the thermally conductive silicone resin composition of the present invention is more preferably a one-terminal trimethoxysilyldimethylsiloxane-methylphenylsiloxane copolymer. This effectively suppresses the solidification of the surface-treated layer formed on the surface of the thermally conductive filler (C) by the surface-treating agent (D) under low-temperature conditions. Furthermore, the dispersibility of the thermally conductive filler (C) in the silicone resin component is further improved, enabling a high filling level of the thermally conductive filler (C), thereby improving the thermal conductivity properties of the cured product of the thermally conductive silicone resin composition.

[0027] Furthermore, the thermally conductive silicone resin composition of the present invention preferably has a cured product having a thermal conductivity of 1.0 W / m·K or greater. This allows the production of a cured product of a thermally conductive member having excellent thermal conductivity even under low temperature conditions.

[0028] The thermally conductive silicone resin composition of the present invention preferably has a cured product having an Asker C hardness (according to JIS K6249) of 60 or less. This allows for a cured product having good conformability and adhesion to the surface of an adherend even under low temperature conditions.

[0029] The heat conduction member of the present invention is formed from a cured product of the heat conductive silicone resin composition. Due to its combined flexibility at low temperatures and high heat conductivity, it has excellent adhesion to adherends even in low-temperature environments and can stably function as a heat conduction medium.

[0030] Furthermore, the heat conduction member for semiconductor etching equipment of the present invention is formed from a cured product of the aforementioned thermally conductive silicone resin composition. Due to its combined flexibility at low temperatures and high thermal conductivity, the heat conduction member is less likely to experience an increase in hardness (hardening) even under the high plasma power etching conditions encountered during semiconductor etching. This maintains close contact with both the focus ring and the stage, thereby stably suppressing temperature increases in the focus ring. This effective suppression of the focus ring's temperature increases enables continuous and stable plasma etching.

[0031] Effects of the Invention

[0032] The thermally conductive silicone resin composition of the present invention comprises a silicone resin component, a thermally conductive filler (C), and a mono-terminal hydrolyzable polyorganosiloxane as a surface treatment agent (D) for treating the surface of the thermally conductive filler (C). The silicone resin component comprises a silicone resin component containing a polyorganosiloxane (A) having alkenyl groups at at least both ends, a hydrogen polyorganosiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (E). Components (A) and (B) are polyorganosiloxanes having at least one phenyl group introduced into each molecule. Since the components are incorporated within a specific blending ratio and the low-temperature change rate of the complex elastic modulus of the cured product, determined by dividing the absolute value of the difference between the complex elastic modulus at 20°C and -80°C by the complex elastic modulus at 20°C, is 1000% or less, a cured product having both low-temperature flexibility and high thermal conductivity can be obtained even when the blending ratio of the thermally conductive filler is increased to achieve a high filling ratio. Furthermore, the heat-conductive member formed from the cured product of the thermally conductive silicone resin composition of the present invention exhibits both low-temperature flexibility and high thermal conductivity, resulting in excellent adhesion to adherends even in low-temperature environments, allowing it to stably function as a heat-conducting medium. Furthermore, in semiconductor etching processes, even when the wafer is used in contact with the stage under low-temperature conditions to cool the wafer during high-power plasma etching, this member maintains close contact with the stage and focus ring, stably suppressing the temperature rise of the focus ring over time. This allows for uniform plasma etching across the entire wafer surface, reduces the frequency of maintenance due to abnormal focus ring temperature increases, and improves semiconductor quality and productivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] [ Figure 1 ] is a cross-sectional view showing an example of the structure of a plasma etching device.

[0034] [ Figure 2 ] is a cross-sectional view showing an example of a structure in which a heat conduction member is provided in a plasma etching apparatus and an embodiment of a heat conduction member for a semiconductor etching apparatus of the present invention. DETAILED DESCRIPTION

[0035] The thermally conductive silicone resin composition of the present invention comprises a silicone resin component, a thermally conductive filler (C), and a surface treatment agent (D) for surface-treating the thermally conductive filler (C), wherein the silicone resin component comprises a polyorganosiloxane (A) having alkenyl groups at at least both ends, a hydrogen polyorganosiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (E), wherein the component (A) is a phenyl-modified polyorganosiloxane having at least one phenyl group in one molecule, and the component (B) is a hydrosilylation catalyst (E). A phenyl-modified hydrogen polyorganosiloxane having one phenyl group, wherein the blending ratio of component (C) is 300 to 2200 parts by weight per 100 parts by weight of the silicone resin component, and component (D) is a single-terminal hydrolyzable polyorganosiloxane, wherein the blending ratio of component (D) is 0.5 to 2 parts by weight per 100 parts by weight of component (C). The cured product has a low-temperature change rate of the complex elastic modulus of 1000% or less, calculated by dividing the absolute value of the difference between the complex elastic modulus at 20°C and -80°C by the complex elastic modulus at 20°C. This is described in detail below.

[0036] (Silicone resin component)

[0037] The silicone resin component constituting the thermally conductive silicone resin composition of the present invention comprises a polyorganosiloxane (A) having alkenyl groups at both ends, a hydrogen polyorganosiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (E). Components (A) and (B) are cured by a crosslinking reaction.

[0038] (Polyorganosiloxane (A))

[0039] The polyorganosiloxane (A) that constitutes the silicone resin component is a polyorganosiloxane having alkenyl groups at at least both ends. It forms the main skeleton of the silicone resin component, forming a cured product through a cross-linking reaction with the hydrogenpolyorganosiloxane (B) described below. Furthermore, polyorganosiloxane (A) is a phenyl-modified polyorganosiloxane having at least one phenyl group in the molecule. Due to the steric hindrance of the phenyl groups in the molecule, it is believed that it is difficult to solidify even at low temperatures and maintains flexibility. Furthermore, during curing through the cross-linking reaction, the stacking effect of the phenyl groups contained in the polyorganosiloxane (A) stably traps unreacted free oil near the cross-linked gel structure, thereby suppressing the leakage of unreacted free oil. Furthermore, the phenyl modification improves the free radical resistance of the silicone resin component, making it less susceptible to plasma-induced deterioration and degradation of the heat conductive component (cured product of the heat conductive silicone resin composition) during plasma etching, thereby improving plasma etching resistance. As an example of the phenyl-modified polyorganosiloxane, a substance represented by the following general formula (1) can be used.

[0040] [Chemistry 1]

[0041]

[0042] Here, in formula (1), R1 is a substituted or unsubstituted monovalent hydrocarbon group that is the same or different, R2 is a phenyl group, R3 and R4 are alkenyl groups, x and y are integers representing the number of each unit, and each unit is arranged in blocks or randomly, preferably randomly. Examples of R1 include: alkyl groups such as methyl, ethyl, propyl, and butyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl and tolyl; aralkyl groups such as benzyl and phenethyl; or halogenated hydrocarbons in which their hydrogen atoms are partially substituted with chlorine atoms, fluorine atoms, etc. Examples of R3 and R4 include vinyl, allyl, butenyl, pentenyl, and hexenyl. From the perspective of material availability, R3 and R4 are preferably vinyl. In addition, the polyorganosiloxane (A) preferably has a straight-chain siloxane chain as in the above-mentioned general formula (1), but the siloxane chain may also have a branched structure. In addition, within the scope that does not impair the effects of the present invention, a portion of the siloxane chain may be substituted with a molecular chain such as a carbon chain.

[0043] (Hydrogenpolysiloxane (B))

[0044] The hydrogen polysiloxane (B) that constitutes the silicone resin component is a compound having at least one silicon-bonded hydrogen atom (hereinafter also referred to as a SiH group) per molecule. It functions as a crosslinking agent, reacting with the alkenyl groups of the aforementioned polyorganosiloxane (A) to cure the thermally conductive silicone resin composition. Hydrogen polysiloxane (B) is a phenyl-modified hydrogen polysiloxane having at least one phenyl group in its molecule. The presence of a phenyl group in the molecule enables it to function similarly to the phenyl groups of polyorganosiloxane (A). This synergistic effect with the phenyl groups of polyorganosiloxane (A) contributes to further low-temperature flexibility and low oil permeability. Furthermore, since hydrogen polysiloxane (B) is also modified with a phenyl group, the free radical resistance of the silicone resin component is enhanced. This reduces plasma-induced degradation of the heat-conductive component (the cured product of the thermally conductive silicone resin composition) during plasma etching, thereby improving plasma etching resistance. As an example of the phenyl-modified hydrogen polyorganosiloxane, a substance represented by the following general formula (2) can be used.

[0045] [Chemistry 2]

[0046]

[0047] Here, in formula (2), R1 represents the same or different substituted or unsubstituted monovalent hydrocarbon groups, R5, R6, and R7 represent R1, phenyl, or -H, at least two of R5, R6, and R7 are hydrogen atoms (-H) bonded to silicon atoms, s and t are integers representing the number of units, and the units are arranged in blocks or randomly, preferably randomly. Examples of R1 include: alkyl groups such as methyl, ethyl, propyl, and butyl; cycloalkyl groups such as cyclopentyl and cyclohexyl; aryl groups such as phenyl and tolyl; aralkyl groups such as benzyl and phenylethyl; or halogenated hydrocarbons in which their hydrogen atoms are partially substituted with chlorine atoms, fluorine atoms, etc. In addition, the hydrogen polysiloxane (B) preferably has a linear siloxane chain as in the general formula (2), but the siloxane chain may also have a branched structure. In addition, within the scope of not impairing the effects of the present invention, a portion of the siloxane chain may be substituted with a molecular chain such as a carbon chain.

[0048] Furthermore, in the thermally conductive silicone resin composition of the present invention, from the perspective of the shape retention of the cured product, the blending ratio of the polyorganosiloxane (A) and hydrogen polyorganosiloxane (B) constituting the silicone resin component is preferably set so that the hardness after the crosslinking reaction is 110 or less in terms of consistency (according to JIS K2220 1 / 4 cone). If the consistency exceeds 110, the curing may be insufficient or oil bleeding may occur. To achieve the hardness range of the silicone resin component described above, the ratio of the number of hydrogen atoms bonded to silicon atoms in the hydrogen polyorganosiloxane (B) to the number of alkenyl groups in the polyorganosiloxane (A) can be 0.5 to 2.

[0049] The polyorganosiloxane (A) and hydrogenpolyorganosiloxane (B) that constitute the silicone resin component can each be composed of a combination of multiple components. Furthermore, a polysiloxane component that functions as a chain extender and reacts with the polymer backbone terminals of the polyorganosiloxane (A) to link the polyorganosiloxanes (A) together can be included. Furthermore, the polyorganosiloxane (A) and hydrogenpolyorganosiloxane (B) are the main components of the silicone resin component of the present invention. However, to fully demonstrate the effects of the present invention, the combined amount of components (A) and (B) preferably accounts for 85% or more of the total silicone resin component, more preferably 90% or more, and particularly preferably 95% or more.

[0050] (Hydrosilylation Catalyst (E))

[0051] The hydrosilylation catalyst (E) constituting the silicone resin component is a component that promotes the crosslinking reaction caused by the hydrosilylation reaction between the alkenyl group in the aforementioned polyorganosiloxane (A) and the SiH group in the aforementioned hydrogen polyorganosiloxane (B), thereby making the silicone resin component easy to cure. The hydrosilylation catalyst (E) is not particularly limited as long as it promotes the above-mentioned crosslinking reaction. A known substance can be appropriately selected and applied. For example, platinum-based, palladium-based, and rhodium-based catalysts can be mentioned. Among them, platinum or platinum compounds that are relatively easy to obtain are preferred. In more detail, for example, platinum element, platinum black, chloroplatinic acid, platinum-olefin complexes, platinum-alcohol complexes, platinum coordination compounds, etc. can be mentioned. One platinum-based catalyst can be used alone, or two or more can be used in combination.

[0052] The amount of the hydrosilylation catalyst (E) incorporated is not particularly limited as long as it is an amount sufficient to promote the crosslinking reaction between the polyorganosiloxane (A) and the hydrogenpolyorganosiloxane (B). Preferably, the amount is 0.1 to 500 ppm, more preferably 1.0 to 100 ppm, calculated as the metal atomic weight of the hydrosilylation catalyst (E) relative to the weight of the silicone resin component. If the content of the hydrosilylation catalyst (E) is less than 1.0 ppm, the catalytic effect may not be achieved. If it exceeds 100 ppm, the catalytic effect is saturated, which is not beneficial from the perspective of raw material costs.

[0053] (Thermal conductive filler (C))

[0054] The thermally conductive filler (C) constituting the thermally conductive silicone resin composition of the present invention is a component that imparts thermal conductivity to the composition, and known thermally conductive fillers can be used. Specifically, a filler composed of at least one material selected from the group consisting of metals, metal oxides, metal hydroxides, metal nitrides, metal carbides, and carbon allotropes is preferred. For example, aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, and silicon carbide, which exhibit excellent heat resistance during use under plasma etching conditions, are more preferred. The shape of the thermally conductive filler (C) can be any of spherical, amorphous, and acicular, and is not particularly limited.

[0055] In addition, from the viewpoint of increasing the filling rate in the thermally conductive silicone resin composition and imparting appropriate fluidity to the thermally conductive silicone resin composition when not cured to improve moldability, the thermally conductive filler (C) is preferably a combination of a large-particle filler and a small-particle filler. The average particle size of the large-particle filler is 10 to 120 μm, preferably 15 to 100 μm, and the average particle size of the small-particle filler is 0.01 to 10 μm, preferably 0.1 to 4 μm. The mixing ratio of the large-particle filler and the small-particle filler is appropriately set according to the filling rate of the thermally conductive filler (C) in the thermally conductive silicone resin composition and the viscosity when not cured. It should be noted that the average particle size of the thermally conductive filler (C) in the present invention can be determined by D in the particle size distribution measurement by the laser diffraction method. 50 (median particle size) to determine.

[0056] From the perspective of achieving the excellent thermal conductivity required of a thermally conductive silicone resin composition and the flexibility of its cured product, the amount of the thermally conductive filler (C) is 300 to 2200 parts by weight, more preferably 500 to 2000 parts by weight, per 100 parts by weight of the silicone resin component. If the amount of the thermally conductive filler (C) is less than 300 parts by weight, the thermally conductive silicone resin composition may not exhibit sufficient thermal conductivity. If the amount exceeds 2200 parts by weight, molding prior to curing may become difficult, and the cured product may not exhibit the flexibility required of a thermally conductive silicone resin composition for semiconductor etching equipment.

[0057] (Surface treatment agent (D))

[0058] The surface treatment agent (D) that constitutes the thermally conductive silicone resin composition of the present invention is a polyorganosiloxane having a hydrolyzable group or a polar functional group bonded to a silicon atom at one end of the molecular chain. It is used to surface-treat the thermally conductive filler (C). Modification of the surface of the thermally conductive filler (C) by the surface treatment agent (D) enhances the affinity between the thermally conductive filler (C) and the silicone resin component, improves the dispersibility of the thermally conductive filler (C) in the silicone resin component, and enhances the adhesion between the interface between the thermally conductive filler (C) and the cured silicone resin component in the cured thermally conductive silicone resin composition. Furthermore, the surface treatment agent (D) serves to inhibit the solidification of the thermally conductive filler (C) in the thermally conductive silicone resin composition at the surface treatment interface, thereby maintaining the flexibility of the cured thermally conductive silicone resin composition under low-temperature conditions, even when the thermally conductive filler filling ratio is high. Among them, the surface treatment agent (D) is preferably a single-terminal hydrolyzable polyorganosiloxane having a hydrolyzable group bonded to a single-terminal silicon atom, from the viewpoint of maintaining the mechanical strength of the cured product containing the thermally conductive filler (C) at a high filling rate by further improving the adhesion at the interface between the thermally conductive filler (C) in the cured product of the thermally conductive silicone resin composition and the cured silicone resin component.

[0059] The one-terminal hydrolyzable polyorganosiloxane of the surface treatment agent (D) is a polyorganosiloxane having a hydrolyzable group (-OR8) bonded to a silicon atom at one end of the molecular chain represented by the following general formula (3). When this hydrolyzable group hydrolyzes, a silanol group is formed at one end of the molecular chain. This silanol group then bonds to a hydroxyl group present on the surface of the thermally conductive filler (C) and undergoes dehydration, thereby forming a surface-treated layer that adheres firmly to the surface of the thermally conductive filler (C). This is believed to improve the dispersibility of the thermally conductive filler (C) in the silicone resin component, enhance the adhesion between the interface between the thermally conductive filler (C) and the cured silicone resin component in the cured thermally conductive silicone resin composition, and, due to the structure of the siloxane chain itself, enhance the flexibility of the cured thermally conductive silicone resin composition under low-temperature conditions.

[0060] [Chemistry 3]

[0061]

[0062] R1 in formula (3) independently represents an unsubstituted or substituted monovalent hydrocarbon group. The monovalent hydrocarbon group of R1 is not particularly limited, but the number of carbon atoms is preferably 1 to 10, more preferably 1 to 6, and even more preferably 1 to 3. Specific examples of the monovalent hydrocarbon group include alkyl, alkenyl, aryl, aralkyl, and halogenated hydrocarbon groups such as haloalkyl groups in which some or all of the hydrogen atoms of these monovalent hydrocarbon groups are substituted with halogen atoms such as chlorine, fluorine, or bromine. Among them, the alkyl group may be any of linear, branched, and cyclic. Specific examples include linear alkyl groups such as methyl, ethyl, n-propyl, n-hexyl, and n-octyl; branched alkyl groups such as isopropyl, isobutyl, tert-butyl, and 2-ethylhexyl; and cyclic alkyl groups such as cyclopentyl and cyclohexyl. Specific examples of the alkenyl group include vinyl, allyl, 1-butenyl, and 1-hexenyl. Specific examples of the aryl group include phenyl and tolyl. Specific examples of aralkyl groups include 2-phenylethyl and 2-methyl-2-phenylethyl. Specific examples of haloalkyl groups include 3,3,3-trifluoropropyl, 2-(nonafluorobutyl)ethyl, and 2-(heptadecafluorooctyl)ethyl. Among these, R1 in formula (3) is preferably a methyl group or a phenyl group.

[0063] In formula (3), n is preferably an integer of 2 to 100, more preferably an integer of 5 to 80, from the perspective of improving the workability, uniformity, and dispersibility of the surface treatment of the thermally conductive filler (C) in the silicone resin component, and maintaining the flexibility of the cured product of the thermally conductive silicone resin composition under low temperature conditions. If n is less than 2, oil bleeding from the cured product may occur. If n is greater than 100, the viscosity of the composition increases, which tends to reduce the workability of the surface treatment of the thermally conductive filler (C).

[0064] In formula (3), R8 constituting the hydrolyzable group (-OR8) independently represents an alkyl group, an alkoxyalkyl group, an alkenyl group, or an acyl group. Examples of the alkyl group for R8 include the same unsubstituted or substituted alkyl groups having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms as the groups exemplified in R1 above, and the same groups as the specific examples can be mentioned. Examples of the alkoxyalkyl group include groups in which the alkoxy group and the alkyl group each have 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms, such as methoxyethyl and methoxypropyl. Examples of the alkenyl group include groups having 2 to 6 carbon atoms, such as vinyl and allyl. Examples of the acyl group include groups having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, such as acetyl and octanoyl. Among these R8 as the hydrolyzable group (-OR8), preferably an alkoxy group in which R8 is an alkyl group, more preferably a methoxy group or an ethoxy group in which R8 is a methyl group or an ethyl group, and particularly preferably a methoxy group. In formula (3), a is an integer of 1 to 3. From the viewpoint of the surface treatment effect of the thermally conductive filler (C), the surface treatment agent (D) is preferably a polyorganosiloxane containing a trialkoxysilyl group at one end, wherein a=3, and particularly preferably a polyorganosiloxane containing a trimethoxysilyl group at one end.

[0065] On the other hand, the polyorganosiloxane having a polar functional group bonded to a silicon atom at one terminal is a polyorganosiloxane having a polar functional group bonded to a silicon atom at one terminal of the molecular chain represented by the following general formula (4). It is believed that the interaction between the polar functional group and the surface of the thermally conductive filler (C) improves the affinity between the thermally conductive filler (C) and the silicone resin component, thereby improving the dispersibility of the thermally conductive filler (C) in the silicone resin component and improving the adhesion between the thermally conductive filler (C) and the cured silicone resin component in the cured thermally conductive silicone resin composition. At the same time, the structure of the siloxane chain itself improves the flexibility of the cured thermally conductive silicone resin composition under low temperature conditions.

[0066] [Chemistry 4]

[0067]

[0068] R1 in formula (4) is the same as R1 in formula (3). R9 in formula (4) is a polar functional group. As long as the effects of the present invention can be obtained, a known functional group can be applied. From the perspective of maintaining the curability of the silicone resin component, it is preferably selected from the group consisting of a vinyl group, an epoxy group, a styryl group, a methacryloyl group, and an acryloyl group. From the perspective of improving the workability, uniformity, and dispersibility of the surface treatment of the thermally conductive filler (C) in the silicone resin component and maintaining the flexibility of the cured product of the thermally conductive silicone resin composition under low temperature conditions, n in formula (4) is preferably an integer of 2 to 100, and more preferably an integer of 5 to 80. If n is less than 2, oil bleeding from the cured product may occur. If n is greater than 100, the viscosity of the composition becomes high, and thus there is a tendency for the workability of the surface treatment of the thermally conductive filler (C) to be reduced. a in the formula is an integer of 1 to 3, and from the perspective of the surface treatment effect of the thermally conductive filler (C), it is preferably 3.

[0069] Furthermore, the surface treatment agent (D) constituting the thermally conductive silicone resin composition of the present invention is preferably modified with a phenyl group in any of the polyorganosiloxanes represented by the aforementioned general formula (3) or general formula (4) by selecting a phenyl group as R1 in general formula (3) or general formula (4) attached to the polysiloxane chain. This effectively suppresses solidification of the surface treatment layer formed on the surface of the thermally conductive filler (C) under low-temperature conditions. Furthermore, the dispersibility of the thermally conductive filler (C) in the silicone resin component is further improved, enabling high filling of the thermally conductive filler (C) and improving the thermal conductivity properties of the thermally conductive silicone resin composition. Furthermore, the phenyl group modification improves the radical resistance of the surface treatment agent (D). Consequently, as the radical resistance of the silicone resin component is improved, plasma-induced deterioration and degradation of the thermally conductive member (cured product of the thermally conductive silicone resin composition) during plasma etching can be further suppressed, further improving plasma etching resistance. Here, when the surface treatment agent (D) is a single-terminal hydrolyzable polyorganosiloxane, it is more preferably a single-terminal trimethoxysilyldimethylsiloxane-methylphenylsiloxane copolymer. The number and bonding position of the phenyl groups bonded to the polysiloxane chain can be appropriately set within the range of achieving the effects of the present invention, but from the perspective of flexibility under low temperature conditions, it is preferably bonded to the silicon atom of the D unit.

[0070] The viscosity of the polyorganosiloxane selected as the surface treatment agent (D) at 25°C is preferably 0.005 to 10 Pa·s, more preferably 0.005 to 1 Pa·s. Within this range, oil bleeding from the cured product is suppressed, and the workability of the surface treatment of the thermally conductive filler (C) and its dispersibility in the silicone resin component are improved, thereby achieving more uniform affinity between the thermally conductive filler (C) and the silicone resin component.

[0071] Furthermore, from the viewpoint of reducing solidification under low temperature conditions, the glass transition temperature Tg of the polyorganosiloxane selected as the surface treatment agent (D) is preferably around -120°C. This can achieve the effect of suppressing the increase in hardness of the surface treatment layer formed near the surface of the thermally conductive filler (C) under low temperature conditions, compared to alkyl-based silane coupling agents such as decyltrimethoxysilane.

[0072] The surface treatment agent (D) may be a single-end hydrolyzable polyorganosiloxane, a single-end functional polyorganosiloxane, a phenyl-modified single-end hydrolyzable polyorganosiloxane, or a phenyl-modified single-end functional polyorganosiloxane, or a combination of two or more thereof. Furthermore, a conventional surface treatment agent such as a silane coupling agent may be used in combination, as long as the effects of the present invention are not impaired.

[0073] The surface treatment agent (D) preferably has a linear siloxane chain structure in any of the polyorganosiloxanes represented by the general formula (3) or the general formula (4). However, the siloxane chain may also have a branched structure. Furthermore, within the scope of not impairing the effects of the present invention, a portion of the siloxane chain may be substituted with a molecular chain such as a carbon chain.

[0074] In the thermally conductive silicone resin composition of the present invention, the surface treatment agent (D) is incorporated in an amount of 0.5 to 2 parts by weight, preferably 0.5 to 1.5 parts by weight, and more preferably 0.8 to 1.2 parts by weight, per 100 parts by weight of the total weight of the thermally conductive filler (C). If the surface treatment agent (D) is incorporated in an amount less than 0.5 parts by weight, the affinity between the thermally conductive filler (C) and the silicone resin component may be poor, resulting in a loss of flexibility after curing. If the surface treatment agent (D) is incorporated in an amount greater than 2 parts by weight, not only may the thermal conductivity be reduced, but the material strength of the cured thermally conductive resin composition may also be reduced.

[0075] (Other ingredients)

[0076] The thermally conductive silicone resin composition of the present invention may contain other components within a range that does not impair the objects and effects of the present invention. For example, various additives for imparting functions such as heat stabilizers, reaction inhibitors for adjusting the curing rate, pigments / dyes for coloring, flame retardants, and release agents for improving release from a mold or a diaphragm may be added.

[0077] For example, a thermal stabilizer is a component that can impart heat resistance and plasma etching resistance to the cured product of the thermally conductive silicone resin composition and can impart the effect of reducing oil seepage. As specific examples of thermal stabilizers, carbon materials such as iron oxide, carbon black, graphite, carbon nanotubes, carbon fibers, iron carboxylates, cesium hydrates, titanium dioxide, barium zirconate, cerium octylate, zirconium octylate, and porphyrins and other well-known substances can be used. Thermal stabilizers of carbon materials that do not act as oxidants under reduced pressure and heating conditions and have excellent free radical capture properties are particularly preferred. Thermal stabilizers can be used alone or in combination. The mixing ratio of the thermal stabilizer is 0.1 to 20 parts by weight relative to a total of 100 parts by weight of the polyorganosiloxane (A) and the hydrogenpolyorganosiloxane (B), more preferably 5 to 15 parts by weight, and particularly preferably 5 to 10 parts by weight. If the blending ratio of the heat stabilizer is less than 5 parts by weight, the heat stabilization effect may not be sufficiently obtained in the cured product of the heat conductive silicone resin composition. If it exceeds 20 parts by weight, the thermal conductivity of the heat conductive silicone resin composition may be reduced, and the heat stabilizer may not be dispersed properly.

[0078] (Method for Preparing Thermally Conductive Silicone Resin Composition)

[0079] The thermally conductive silicone resin composition of the present invention can be easily prepared into an uncured thermally conductive silicone resin composition by combining the aforementioned components in a predetermined ratio and uniformly mixing them. The mixing method is not particularly limited, and a known mixer, kneader, etc. can be used. The uncured thermally conductive silicone resin composition can be cured by being left at room temperature or by heating to promote a cross-linking reaction. In addition, the surface treatment agent (D) can be added by a known method such as spraying the surface treatment agent (D) directly or in a state dispersed in a solvent such as an organic solvent onto the thermally conductive filler (C) or immersing the surface treatment agent (D) in the thermally conductive filler (C), or mixing the silicone resin component, the thermally conductive filler (C), and the surface treatment agent (D) together.

[0080] (Cured material of thermally conductive silicone resin composition)

[0081] The cured product of the thermally conductive silicone resin composition of the present invention has a low-temperature change rate of the complex elastic modulus of 1000% or less. This low-temperature change rate of the complex elastic modulus is calculated by dividing the absolute value of the difference between the complex elastic modulus at 20°C and -80°C by the complex elastic modulus at 20°C. This provides a cured product that forms a heat conductive member with excellent flexibility under low-temperature conditions, stably maintaining close contact with the focus ring and stage in a semiconductor etching apparatus, preventing a decrease in thermal conductivity, and enabling stable plasma etching. The complex elastic modulus in this specification is a value measured under a torsional shear mode at 10 Hz. If the low-temperature change rate of the complex elastic modulus exceeds 1000%, the cured product of the thermally conductive silicone resin composition will not maintain its flexibility under low-temperature conditions, will not be able to follow deformation caused by thermal expansion and contraction of the stage and focus ring due to temperature changes, and the stability of the close contact with the focus ring and stage will be reduced, potentially preventing stable plasma etching.

[0082] The hardness of the cured product of the thermally conductive silicone resin composition of the present invention at room temperature can be appropriately set depending on the intended use. However, from the perspective of workability and adhesion to the adherend, the Asker C hardness (according to JIS K6249) is preferably 60 or less, and more preferably 20 to 60. The reason why the hardness is preferably 20 or greater is that if the Asker C hardness is less than 20, the cured product of the thermally conductive silicone resin composition may be too soft, thereby reducing workability. In addition, if the hardness of the cured product is greater than 60 in terms of Asker C hardness, there is a tendency for the product to be less adaptable to the shape of the adherend or the surface irregularities of the adherend, thereby sometimes reducing good adhesion and increasing thermal resistance at the contact interface.

[0083] Furthermore, the cured product of the thermally conductive silicone resin composition of the present invention functions as a heat-conducting member, as described below. The thermal conductivity of the cured product can be appropriately adjusted depending on the intended use. However, since the cured product is suitable for use as a heat-conducting member in semiconductor etching equipment, the thermal conductivity of the cured product is preferably 1.0 W / m·K or higher, and more preferably 1.5 W / m·K or higher, from the perspective of preventing a temperature rise in the focus ring during plasma etching. The thermal conductivity in the present invention is a value measured using the steady-state method of ASTM D5470, using a sheet measuring 10 mm in length by 10 mm in width by 2.0 mm in thickness as a test specimen. A load of 5 N is applied to the entire surface of the specimen, and the thermal conductivity in the thickness direction is measured at an average temperature of 50°C on the heated and cooled sides.

[0084] (Heat conduction member)

[0085] The heat-conductive member of the present invention is a cured product of the heat-conductive silicone resin composition of the present invention, obtained by molding and curing an uncured heat-conductive silicone resin composition. The heat-conductive member can be used by contacting or placing it in close proximity to a heat-dissipating or heat-absorbing object, thereby transferring heat from the object to another component or the environment. The thickness and shape of the heat-conductive member can be appropriately determined, for example, based on the shape and placement of the adherend, such as a cooling element such as a heat sink or a heat-generating element such as a CPU. However, to reduce thermal resistance in the thickness direction, the heat-conductive member is preferably formed into a thin sheet. The heat-conductive member can be produced by molding an uncured heat-conductive silicone resin composition into a predetermined shape and then allowing the molded product to stand at room temperature or by heating. For example, if the heat-conductive member is in the form of a sheet, the uncured composition can be applied to a substrate film, molded into a sheet by known methods such as calendering, and heat-cured. The cured sheet can then be formed into the desired shape using known methods such as punching, laser processing, and drawing to obtain the heat-conductive member.

[0086] In addition, the surface of the heat conduction component of the present invention may be adhesive or non-adhesive. In addition, from the perspective of the ease of assembly and disassembly with the cooling body and the heating body as adherends, the adhesiveness of the surface in contact with the cooling body side and the surface in contact with the heating body side may be different. The method of imparting adhesiveness to the surface of the heat conduction component may be a method of imparting adhesiveness by adding a tackifier to the heat conductive silicone resin composition, a method of applying an adhesive coating to the surface of the heat conduction component, and other known methods. In addition, when making the surface of the heat conduction component non-adhesive, a method of using a non-adhesive silicone resin component, applying a non-adhesive coating to the surface of the heat conduction component, or performing surface modification such as excimer treatment or plasma treatment may be applied.

[0087] (Heat conduction member for semiconductor etching equipment)

[0088] Furthermore, the heat conduction member of the present invention can be suitably used as a heat conduction member for a semiconductor etching device. Figure 2 As shown, the heat conduction member 5 for this semiconductor etching apparatus is interposed between the focus ring 3 and the stage 2 to form a heat conduction path. The thickness and shape of the heat conduction member 5 can be appropriately determined based on the shape and configuration of the focus ring 3 and the stage 2, but a thin sheet is preferably used to reduce thermal resistance in the thickness direction. This heat conduction member 5 exhibits excellent flexibility under harsh low-temperature conditions, thus maintaining stable contact with the focus ring 3 and the stage 2 in the semiconductor etching apparatus, preventing a decrease in thermal conductivity and enabling stable plasma etching processing.

[0089] Example

[0090] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not particularly limited to these Examples.

[0091] The methods for measuring physical properties and evaluating effects in the following Examples and Comparative Examples are as follows.

[0092] (1) Thermal conductivity (thermal conductivity)

[0093] The uncured thermally conductive silicone resin composition was formed into a sheet with a thickness of 2.0 mm by calendering. After preheating at 70°C for 1 hour in a hot air oven (manufactured by Tokyo Riko Instruments Co., Ltd., WFO-520W), the sheet was heated at 100°C for 3 hours to obtain a sheet-like cured product of the thermally conductive silicone resin composition with a thickness of 2.0 mm. The sheet-like cured product was punched out into 10 mm × 10 mm pieces using a Thomson die to produce a sheet-like test piece. A load of 5 N was applied to the entire surface of the test piece using the steady-state method according to ASTM D5470. The thermal conductivity in the thickness direction was measured under the condition that the average temperature of the heating and cooling sides was 50°C. The average thermal conductivity of the three test pieces was calculated. The measuring apparatus used was a resin material thermal resistance measuring apparatus (manufactured by Hitachi Technology & Service Co., Ltd.). A thermal conductivity of 1 W / m·K or more was judged as acceptable (0), and a value of less than 1 W / m·K was judged as unacceptable (×).

[0094] (2) Hardness of the cured product at room temperature (softness at room temperature, C hardness: H0)

[0095] The hardness of test specimens formed from cured thermally conductive silicone resin compositions was measured using an Asker C durometer (SRIS 0101 standard, "Asker Rubber Durometer C" manufactured by Kobunsu Keiki Co., Ltd.) in accordance with JIS K6253. The test specimens were formed by molding each of the uncured thermally conductive silicone resin compositions from the Examples and Comparative Examples into a mold having a size of 60 mm long x 60 mm wide x 12 mm thick. The molds were then preheated in a hot air oven (WFO-520W manufactured by Tokyo Rika Kikai Co., Ltd.) at 70°C for 1 hour and then cured by heating at 100°C for 3 hours.

[0096] (3) Low-temperature flexibility (low-temperature change rate of complex elastic modulus G*)

[0097] The uncured thermally conductive silicone resin composition was calendered to form a sheet with a thickness of 2 mm, and then preheated in a hot air oven (WFO-520W manufactured by Tokyo Riko Kikai Co., Ltd.) at 70°C for 1 hour and then heated at 100°C for 3 hours to obtain a sheet-like cured product of the thermally conductive silicone resin composition with a thickness of 2 mm. The cured product was punched into Made of The complex modulus of a thick, circular specimen was measured at 10 Hz using a dynamic viscoelasticity measuring apparatus (ARES-G2; manufactured by TA Instruments) over a temperature range of -80°C to 20°C under a load of 100 g. The low-temperature change rate (%) was calculated by dividing the absolute value of the change between the complex elastic modulus at -80°C (G*1) and the complex elastic modulus at 20°C (G*0) (G*1-G*0) by the complex elastic modulus at 20°C (G*0). A low-temperature change rate of 1000% or less was considered acceptable (0), while a value exceeding 1000% was considered unacceptable (×).

[0098] [Example 1]

[0099] As the silicone resin component (I), a two-liquid addition reaction-type silicone gel (SEMICOSIL (registered trademark) 920LT, manufactured by Asahi Kasei Wacker Silicones Co., Ltd.) was used. Liquid A, which was a mixture of a phenyl-modified polyorganosiloxane having vinyl groups at both ends with a hydrosilylation catalyst (E), and liquid B, which was a mixture of a phenyl-modified hydrogen polyorganosiloxane with the same polyorganosiloxane (A), as the polyorganosiloxane (B), were blended at a weight ratio of 58:42 to prepare 100 g of the silicone resin component. On the other hand, as a thermally conductive filler (C), 1000 g of a three-component alumina powder is prepared, which is composed of 600 g of a first alumina powder (DAW-70 manufactured by DENKA Corporation, with an average particle size of 70 μm), 300 g of a second alumina powder (CB-P05 manufactured by Showa Denko K.K., with an average particle size of 5 μm), and 100 g of a third alumina powder (AA-03F manufactured by Sumitomo Chemical Co., Ltd., with an average particle size of 0.2 to 0.4 mm). As the surface treatment agent (D) for the thermally conductive filler (C), 10 g of a one-terminal trimethoxysilyldimethylsiloxane-methylphenylsiloxane copolymer (D1) (Z5804, manufactured by Tokyo Chemical Industry Co., Ltd., viscosity 30 mPa·s, 88-94% dimethylsiloxane, 6-12% methylphenylsiloxane) containing a structure in which a phenyl group is bonded to the polysiloxane chain was prepared (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). 100 g of the silicone resin component, 1000 g of the thermally conductive filler (C), and 10 g of the surface treatment agent (D) were placed in a planetary mixer (ACM-5LVT, manufactured by Aikosha Manufacturing Co., Ltd.) and mixed at 150 rpm for 10 minutes under atmospheric pressure. The mixture was then further mixed at 150 rpm for 10 minutes under reduced pressure of -0.1 MPa. The mixture was then degassed under reduced pressure to obtain the uncured thermally conductive silicone resin composition of Example 1. The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0100] [Example 2]

[0101] The uncured thermally conductive silicone resin composition of Example 2 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 500 g of a three-component alumina powder consisting of 300 g of the first alumina powder, 150 g of the second alumina powder, and 50 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 5 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) were measured and the effects of the composition were evaluated.

[0102] [Example 3]

[0103] An uncured thermally conductive silicone resin composition of Example 3 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 1500 g of a three-component alumina powder consisting of 900 g of the first alumina powder, 450 g of the second alumina powder, and 150 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 15 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) were measured and the effects of the composition were evaluated.

[0104] [Example 4]

[0105] An uncured thermally conductive silicone resin composition of Example 4 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 2000 g of a three-component alumina powder consisting of 1200 g of the first alumina powder, 600 g of the second alumina powder, and 200 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 20 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) were measured and the effects of the composition were evaluated.

[0106] [Example 5]

[0107] An uncured thermally conductive silicone resin composition of Example 5 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 2200 g of a three-component alumina powder consisting of 1320 g of the first alumina powder, 660 g of the second alumina powder, and 220 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 22 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0108] [Example 6]

[0109] The uncured thermally conductive silicone resin composition of Example 6 was obtained in the same manner as in Example 1 except that the amount of the surface treatment agent (D1) used in Example 1 was changed to 5 g (0.5 parts by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0110] [Example 7]

[0111] An uncured thermally conductive silicone resin composition of Example 7 was obtained in the same manner as in Example 1, except that the amount of the surface treatment agent (D1) used in Example 1 was changed to 20 g (2.0 parts by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) were measured and the effects were evaluated for this thermally conductive silicone resin composition.

[0112] [Example 8]

[0113] An uncured thermally conductive silicone resin composition of Example 8 was obtained in the same manner as in Example 1, except that the surface treatment agent (D1) used in Example 1 was replaced with a polyorganosiloxane (D2) containing a trialkoxysilyl group at one end (manufactured by Shin-Etsu Chemical Co., Ltd., X24-9011, no phenyl group bonded to the polysiloxane chain). The thermally conductive silicone resin composition was subjected to the measurement of the physical properties (1) to (3) above and the evaluation of its effects.

[0114] [Example 9]

[0115] The uncured thermally conductive silicone resin composition of Example 9 was obtained in the same manner as in Example 8 except that the amount of the thermally conductive filler (C) used in Example 8 was replaced with 500 g of a three-component alumina powder consisting of 300 g of the first alumina powder, 150 g of the second alumina powder, and 50 g of the third alumina powder, and the amount of the surface treatment agent (D2) used in Example 8 was changed to 5 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) were measured and the effects of the composition were evaluated.

[0116] [Example 10]

[0117] The uncured thermally conductive silicone resin composition of Example 10 was obtained in the same manner as in Example 8 except that the amount of the thermally conductive filler (C) used in Example 8 was replaced with 1200 g of a three-component alumina powder consisting of 720 g of the first alumina powder, 360 g of the second alumina powder, and 120 g of the third alumina powder, and the amount of the surface treatment agent (D2) used in Example 8 was changed to 12 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0118] [Example 11]

[0119] The uncured thermally conductive silicone resin composition of Example 11 was obtained in the same manner as in Example 8 except that the amount of the thermally conductive filler (C) used in Example 8 was replaced with 1500 g of a three-component alumina powder consisting of 900 g of the first alumina powder, 450 g of the second alumina powder, and 150 g of the third alumina powder, and the amount of the surface treatment agent (D2) used in Example 8 was changed to 15 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0120] [Example 12]

[0121] The uncured thermally conductive silicone resin composition of Example 12 was obtained in the same manner as in Example 8 except that the amount of the thermally conductive filler (C) used in Example 8 was replaced with 1800 g of a three-component alumina powder consisting of 1080 g of the first alumina powder, 540 g of the second alumina powder, and 180 g of the third alumina powder, and the amount of the surface treatment agent (D2) used in Example 8 was changed to 18 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0122] [Example 13]

[0123] An uncured thermally conductive silicone resin composition of Example 13 was obtained in the same manner as in Example 9, except that the amount of the surface treatment agent (D2) used in Example 9 was changed to 2.5 g (0.5 parts by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0124] [Example 14]

[0125] The uncured thermally conductive silicone resin composition of Example 14 was obtained in the same manner as in Example 9 except that the amount of the surface treatment agent (D2) used in Example 9 was changed to 10 g (2.0 parts by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0126] [Example 15]

[0127] An uncured thermally conductive silicone resin composition of Example 15 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 320 g of a three-component alumina powder consisting of 192 g of the first alumina powder, 96 g of the second alumina powder, and 32 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 3.2 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0128] [Comparative Example 1]

[0129] An uncured thermally conductive silicone resin composition of Comparative Example 1 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 200 g of a three-component alumina powder consisting of 120 g of the first alumina powder, 60 g of the second alumina powder, and 20 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 2 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The above-mentioned physical properties (1) to (3) were measured and the effects of the composition were evaluated.

[0130] [Comparative Example 2]

[0131] An uncured thermally conductive silicone resin composition of Comparative Example 2 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 2500 g of a three-component alumina powder consisting of 1500 g of the first alumina powder, 750 g of the second alumina powder, and 250 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 25 g (1.0 part by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0132] [Comparative Example 3]

[0133] As the silicone resin component (II) of this comparative example, Liquid A of a two-part addition-reaction silicone gel (CF5106, manufactured by Dow Corning Toray Co., Ltd.) and Liquid B of the two-part addition-reaction silicone gel (SEMICOSIL 920LT, manufactured by Asahi Kasei Wacker Silicones Co., Ltd.) used in Example 2 were used. Liquid A of the two-part addition-reaction silicone gel (CF5106, manufactured by Dow Corning Toray Co., Ltd.) contained a polyorganosiloxane component (Component a) having vinyl groups at both ends and a hydrosilylation catalyst (E). However, this polyorganosiloxane component (Component a) was an unmodified polyorganosiloxane lacking phenyl groups in its molecule. Liquid A and Liquid B of the two-part addition-reaction silicone gel used in Example 2 were blended in a weight ratio of 50:50 to prepare 100 g of silicone resin component (II). The uncured thermally conductive silicone resin composition of Comparative Example 3 was obtained by following the same procedures as in Example 2 with the exception of these procedures. The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0134] [Comparative Example 4]

[0135] As the silicone resin component (III) of this comparative example, Liquid A of the two-part addition-reaction silicone gel (SEMICOSIL 920LT, manufactured by Asahi Kasei Wacker Silicones) used in Example 2 and Liquid B of the two-part addition-reaction silicone gel (CF5106, manufactured by Dow Corning Toray Industries, Inc.) used in Comparative Example 3 were used. Liquid B of the two-part addition-reaction silicone gel (CF5106, manufactured by Dow Corning Toray Industries, Inc.) contained a mixture of a hydrogen polysiloxane (component b) that lacks phenyl groups in its molecule and is not modified with phenyl groups, and a polysiloxane (component a) that is not modified with phenyl groups and has vinyl groups at both ends. Liquid A of the two-part addition-reaction silicone gel used in Example 2 and Liquid B were blended in a weight ratio of 50:50 to prepare 100 g of silicone resin component (III). The uncured thermally conductive silicone resin composition of Comparative Example 4 was obtained by following the same procedures as in Example 2 with the exception of these procedures. The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0136] [Comparative Example 5]

[0137] As the silicone resin component (IV) of this comparative example, liquid A and liquid B of the two-liquid addition reaction type silicone gel (CF5106 manufactured by Dow Corning Toray Co., Ltd.) used in comparative examples 3 and 4 were used. The polyorganosiloxane (component a) and hydrogen polyorganosiloxane (component b) contained in liquid A and / or liquid B do not have phenyl groups in their molecules and are not phenyl-modified. Liquid A and liquid B were mixed in a weight ratio of 50:50 to prepare 100 g of silicone resin component (IV). Except for this, the same operation was carried out as in Example 2 to obtain an uncured thermally conductive silicone resin composition of comparative example 5. The above-mentioned physical properties (1) to (3) and the effect evaluation were performed on this thermally conductive silicone resin composition.

[0138] [Comparative Example 6]

[0139] An uncured thermally conductive silicone resin composition of Comparative Example 6 was obtained in the same manner as in Example 1 except that the amount of the thermally conductive filler (C) used in Example 1 was replaced with 1800 g of a three-component alumina powder consisting of 1080 g of the first alumina powder, 540 g of the second alumina powder, and 180 g of the third alumina powder, and the amount of the surface treatment agent (D1) used in Example 1 was changed to 3.6 g (0.2 parts by weight relative to 100 parts by weight of the total amount of the thermally conductive filler (C)). The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0140] [Comparative Example 7]

[0141] An uncured thermally conductive silicone resin composition of Comparative Example 7 was obtained in the same manner as in Example 1, except that the surface treatment agent (D1) used in Example 1 was replaced with n-decyltrimethoxysilane (D3) (manufactured by Dow Toray Industries, Ltd., DOWSIL Z-6210 Silane). The thermally conductive silicone resin composition was subjected to the measurement of the physical properties and effect evaluation of the above-mentioned (1) to (3).

[0142] The results of Examples 1 to 7 are shown in Table 1, and the results of Examples 8 to 15 are shown in Table 2.

[0143] [Table 1]

[0144]

[0145] [Table 2]

[0146]

[0147] In addition, the results of Comparative Examples 1 to 7 are shown in Table 3.

[0148] [Table 3]

[0149]

[0150] The results of Examples 1 to 15 shown in Tables 1 and 2 demonstrate that the thermally conductive silicone resin composition having the composition of the present invention exhibits physical properties such as a cured product having an Asker C hardness of 60 or less and a thermal conductivity of 1.0 W / m·K or greater, exhibiting excellent room-temperature flexibility and thermal conductivity. Furthermore, the cured product exhibits excellent low-temperature flexibility, with the low-temperature change rate of the complex elastic modulus (calculated by dividing the absolute value of the difference between the complex elastic modulus at 20°C and -80°C by the complex elastic modulus at 20°C) being 1000% or less. This demonstrates that the present invention maintains the low-temperature flexibility of the cured product even when the blending ratio of the thermally conductive filler (C) in the thermally conductive silicone resin composition is set within a wide range of 300 to 2200 parts by weight per 100 parts by weight of the silicone resin component.

[0151] Furthermore, a comparison of the results of Examples 1 to 7 and 15 with the results of Examples 8 to 14 shows that, regardless of whether the surface treatment agent (D) was a phenyl-modified, trialkoxysilyl-terminated polyorganosiloxane (D1) having a phenyl group bonded to the polysiloxane chain, or the unphenyl-modified, trialkoxysilyl-terminated polyorganosiloxane (D2) was used, a thermally conductive silicone resin composition was obtained that formed a cured product having excellent low-temperature flexibility. Furthermore, it was found that, compared to the case of using the unphenyl-modified, trialkoxysilyl-terminated polyorganosiloxane (D2), the use of the phenyl-modified, trialkoxysilyl-terminated polyorganosiloxane (D1) as the surface treatment agent (D) further reduced the low-temperature change rate and provided a thermally conductive member with further improved flexibility under low-temperature conditions.

[0152] On the other hand, the results of Comparative Examples 1 to 8 shown in Table 3 show that thermally conductive silicone resin compositions that do not have the composition of the present invention cannot achieve the effects of the present invention. Specifically, according to the results of Comparative Example 1, when the amount of thermally conductive filler (C) was 200 parts by weight per 100 parts by weight of the silicone resin component, the thermal conductivity was 0.7 W / m·K, indicating a significant decrease in thermal conductivity. Furthermore, according to the results of Comparative Example 2, when the amount of thermally conductive filler (C) was 2500 parts by weight per 100 parts by weight of the silicone resin component, the silicone resin component was too low to allow molding and evaluation. Furthermore, according to the results of Comparative Examples 3 to 5, when at least one of the polyorganosiloxane (A) and hydrogenpolyorganosiloxane (B) constituting the silicone resin component was not phenyl-modified, the low-temperature flexibility of the cured product was significantly reduced. This indicates that having both components (A) and (B) constituting the silicone resin component have phenyl groups is crucial in the present invention.

[0153] Furthermore, the results of Comparative Example 6 show that if the blending ratio of the surface treatment agent (D) is less than 0.5 parts by weight per 100 parts by weight of the total weight of the thermally conductive filler (C), sufficient affinity between the thermally conductive filler (C) and the silicone resin component cannot be achieved. Comparisons of the blending ratio of the thermally conductive filler (C) under the same conditions (Example 4) or similar conditions (Example 12) show that the hardness of the cured product increases, while room-temperature flexibility decreases, and low-temperature flexibility also decreases. Furthermore, although not shown in these Examples and Comparative Examples, it is clear that if the blending ratio of the surface treatment agent (D) exceeds 2 parts by weight per 100 parts by weight of the total weight of the thermally conductive filler (C), the thermal conductivity of the cured product significantly decreases. These results demonstrate that it is important to maintain a blending ratio of the surface treatment agent (D) between 0.5 and 2 parts by weight.

[0154] Furthermore, the results of Comparative Example 7 show that when the silane-based surface treatment agent n-decyltrimethoxysilane (D3) is used as the surface treatment agent (D) instead of the polyorganosiloxane containing a trialkoxysilyl group at one end (D1), the low-temperature flexibility of the cured product of the thermally conductive silicone resin composition is significantly reduced. This demonstrates that in order to achieve flexibility and high thermal conductivity in a cured product (thermal conductive member) under severe low-temperature conditions, it is important to incorporate the configuration of the present invention.

[0155] Industrial applicability

[0156] The thermally conductive silicone resin composition of the present invention can form a cured product (heat-conductive member) that exhibits both excellent flexibility and high thermal conductivity under low-temperature conditions. Therefore, it can be widely used in industries such as electronic equipment requiring heat dissipation measures, such as semiconductor etching processing, and equipment used in space and extremely cold regions.

[0157] Explanation of symbols

[0158] 1 substrate mounting unit

[0159] 2 mounting platform (lower electrode unit)

[0160] 2a Suction cup mechanism (wafer suction cup, etc.)

[0161] 2b support platform

[0162] 3 Focus rings (edge ​​rings)

[0163] 4 Cooling units

[0164] 5. Heat conduction components

[0165] W substrate to be processed (wafer, etc.)

Claims

1. A thermally conductive silicone resin composition comprising a silicone resin component, a thermally conductive filler (C), and a surface treatment agent (D) for surface-treating the thermally conductive filler (C), wherein the silicone resin component comprises a polyorganosiloxane (A) having alkenyl groups at at least both ends, a hydrogen polyorganosiloxane (B) having at least one hydrogen atom bonded to a silicon atom in one molecule, and a hydrosilylation catalyst (E), wherein: The component (A) is a phenyl-modified polyorganosiloxane having at least one phenyl group in its molecule. The component (B) is a phenyl-modified hydrogen polysiloxane having at least one phenyl group in its molecule. The mixing ratio of the component (C) is 300 to 2200 parts by weight relative to 100 parts by weight of the silicone resin component. The component (D) is a single-terminal hydrolyzable polyorganosiloxane having a hydrolyzable group bonded to a single-terminal silicon atom, and the blending ratio of the component (D) is 0.5 to 2 parts by weight relative to 100 parts by weight of the component (C). The cured product of the thermally conductive silicone resin composition has a low-temperature change rate of complex elastic modulus of 1000% or less, where the low-temperature change rate of complex elastic modulus is obtained by dividing the absolute value of the difference between the complex elastic moduli at 20°C and -80°C by the complex elastic modulus at 20°C.

2. The thermally conductive silicone resin composition according to claim 1, wherein The hydrolyzable group in the one-end hydrolyzable polyorganosiloxane of the component (D) is an alkoxy group.

3. The thermally conductive silicone resin composition according to claim 1, wherein The one-end hydrolyzable polyorganosiloxane of the component (D) is a polyorganosiloxane containing a trialkoxysilyl group at one end.

4. The thermally conductive silicone resin composition according to claim 1, wherein The one-end hydrolyzable polyorganosiloxane of the component (D) has a phenyl group bonded to a polysiloxane chain.

5. The thermally conductive silicone resin composition according to claim 1, wherein The one-terminal hydrolyzable polyorganosiloxane of the component (D) is a one-terminal trimethoxysilyldimethylsiloxane-methylphenylsiloxane copolymer.

6. The thermally conductive silicone resin composition according to claim 1, wherein The thermal conductivity of the cured product is 1.0 W / m·K or higher.

7. The thermally conductive silicone resin composition according to claim 1, wherein The hardness of the cured product is 60 or less in terms of Asker C hardness in accordance with JIS K6249.

8. A heat conducting member, characterized in that: The thermally conductive silicone resin composition is formed from a cured product of the thermally conductive silicone resin composition according to any one of claims 1 to 7.

9. A heat conduction member for a semiconductor etching device, characterized in that: The thermally conductive silicone resin composition is formed from a cured product of the thermally conductive silicone resin composition according to any one of claims 1 to 7.

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