Holding device

Abstract

To suppress a problem caused by stress generated in a joining unit by improving cooling performance in a holding device even when heat input to a plate-like unit for holding an object becomes large.SOLUTION: A holding device for holding an object includes: a plate-like unit formed in a plate-like shape; a cooling unit that is formed in a plate-like shape and cools the plate-like unit; and a joining unit arranged between the plate-like unit and the cooling unit and joining the facing surfaces of the plate-like unit and the cooling unit to each other. The joining unit has a silicone adhesive and surface-coated aluminum nitride particles. The value of O / Al is 1.4 or more and 4.0 or less, which is an atomic ratio of an oxygen atom on an outermost surface of the surface-coated aluminum nitride particle and an aluminum atom.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This disclosure relates to a holding device. [Background technology]

[0002] Conventionally, as a holding device for holding objects, for example, when manufacturing semiconductors, a holding device for wafers etc. Electrostatic chucks are known for holding objects. Generally, electrostatic chucks are used when the object is placed on them. A ceramic part, a base part in which a refrigerant flow path is formed, and a connection between the ceramic part and the base part. It comprises a joint that fits together. For example, Patent Document 1 describes a silicone adhesive and silicon dioxide Aluminum nitride particles with a coating layer made of a material formed on their surface, and a bonding layer containing (bonding) An electrostatic chuck with a section (part) is described. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2007-194320 [Overview of the project] [Problems that the invention aims to solve]

[0004] According to the technology described in Patent Document 1 above, silicone resin is used as the material for the joint. This relieves the stress generated at the joint due to the difference in thermal conductivity between the ceramic part and the base part. Furthermore, the surface of aluminum nitride particles, which have relatively high thermal conductivity, is coated with silicon dioxide. This enhances the water resistance of the aluminum nitride particles and improves the durability of the joints and electrostatic chucks. This is increasing the power of the plasma. However, for example, in electrostatic chucks, the plasma is more powerful and powerful. When used exposed to the elements, the heat input to the ceramic part increases, and the object being held also increases. By setting the temperature of the base lower to ensure sufficient cooling, the ceramic part and the base The temperature difference between the joint and the surrounding area increases, resulting in greater stress at the joint. It is possible. Therefore, even in such cases, the cooling performance of the holding device should be improved. Therefore, there was a need for technology to suppress problems caused by stress at the joint. [Means for solving the problem]

[0005] This disclosure can be implemented in the following forms: (1) According to one embodiment of the present disclosure, a holding device for holding an object is provided. It comprises a plate-shaped portion formed in the shape of a plate, a cooling portion formed in the shape of a plate for cooling the plate-shaped portion, and It is positioned between the plate-shaped portion and the cooling portion, and joins the opposing surfaces of the plate-shaped portion and the cooling portion. The device comprises a joint, the joint being a silicone adhesive and a surface coating aluminum nitride Aluminum particles, and the oxygen atoms and aluminum atoms at the outermost surface of the surface-coated aluminum nitride particles. The atomic ratio of O / Al, which is the ratio of aluminum atoms to titanium atoms, is between 1.4 and 4.0. According to this form of holding device, silica on the surface of surface-coated aluminum nitride particles Because the wettability with the ion-based adhesive is enhanced, problems caused by stress at the joint This can be suppressed. And even when the heat input to the plate-like part is large, the surface By using coated aluminum nitride particles, the cooling performance in the holding device can be improved. It is possible. (2) In the above-described holding device, the thermal resistance of the joint is 5.0 × 10 -4 m 2 K / W The following configuration may also be adopted. With such a configuration, the thermal resistance of the joint can be suppressed. As a result, heat transfer between the plate-shaped portion and the cooling portion is improved, and the cooling performance of the holding device can be further enhanced. This is possible. (3) In the holding device of the above-described embodiment, the thickness of the joint portion may be 400 μm or less. With such a configuration, by suppressing the thermal resistance of the joint portion, heat transfer between the plate-shaped portion and the cooling portion is improved, and the cooling performance of the holding device can be further enhanced. (4) In the holding device of the above-described embodiment, the content ratio of the surface-coated aluminum nitride particles in the joint portion may be 70% by mass or more. With such a configuration, the thermal conductivity of the joint portion can be further increased. (5) In the holding device of the above-described embodiment, when the radius of the inscribed circle of the surface-coated aluminum nitride particles in the cross-sectional view is R1 and the radius of the circumscribed circle is R2, the average value of the R2 / R1 value may be 1.10 or more. With such a configuration, in the joint portion, more contacts between the surface-coated aluminum nitride particles are formed, and heat conduction paths are easily formed within the joint portion, and the thermal resistance of the joint portion can be suppressed. (6) In the holding device of the above-described embodiment, the maximum shear strain of the joint portion may be 0.5 mm or more. With such a configuration, the effect of suppressing the inconvenience caused by the stress generated in the joint portion can be enhanced. (7) According to another embodiment of the present disclosure, a holding device for holding an object is provided. This holding device includes a plate-shaped portion formed in a plate shape, a cooling portion formed in a plate shape for cooling the plate-shaped portion, a joint portion disposed between the plate-shaped portion and the cooling portion and joining the opposing surfaces of the plate-shaped portion and the cooling portion, and the joint portion includes a silicone-based adhesive and surface-coated aluminum nitride <00The material contains nium particles, and the thermal conductivity of the joint is 0.8 W / (m·K) or more, and the The maximum shear strain at the joint is 0.5 mm or more. With this type of holding device, even when the heat input to the plate-shaped part is large, the holding To improve the cooling performance of the device and to suppress problems caused by stress at the joints. It is possible. (8) In the above-described holding device, the plate-shaped portion is mainly composed of ceramic, and the target It includes an adsorption electrode for holding an object, but does not include a heater electrode for heating the object. This may also be done. With this configuration, the heater electrode heats the object and the plate-like part. Even when not heated, the heat input to the plate-like part is large, and the temperature difference between the plate-like part and the base is In usage conditions where the size tends to increase, the cooling performance of the holding device is improved, and the joints This method significantly reduces the problems caused by the resulting stress. This disclosure can be implemented in various forms other than those described above, for example, a semiconductor-made device including a holding device. This can be realized in the form of a manufacturing device, a method for manufacturing a holding device, or a method for forming a joint. [Brief explanation of the drawing]

[0006] [Figure 1] A perspective view showing a schematic representation of the appearance of the electrostatic chuck according to the embodiment. [Figure 2] A schematic cross-sectional view showing the configuration of an electrostatic chuck. [Figure 3] An explanatory diagram showing how to determine the "R2 / R1" ratio of inorganic filler particles. [Figure 4] An explanatory diagram showing how heat transfer paths are formed between inorganic filler particles. [Figure 5] An explanatory diagram regarding the stress generated at the joint. [Figure 6] An explanatory diagram illustrating how a joint stretches when shear stress occurs. [Figure 7] An explanatory diagram summarizing the measurement and evaluation results for each sample. [Figure 8] An explanatory diagram outlining the procedure for measuring the thermal conductivity of a joint. [Figure 9] A schematic diagram illustrating how to determine the strain amount at maximum shear stress. [Modes for carrying out the invention]

[0007] A. Structure of electrostatic chuck: Figure 1 is a perspective view showing a schematic appearance of the electrostatic chuck 10 in the embodiment. Figure 2 is This is a schematic cross-sectional view showing the configuration of the electrostatic chuck 10. Figure 1 shows the electrostatic chuck 10 A portion is shown broken off. Also, in Figures 1, 2, and later in Figures 5 and 8, the direction is indicated. To clarify, mutually orthogonal X, Y, and Z axes are shown. The X, Y, and Z axes are shown in each figure. Each axis represents the same direction. In this specification, the Z-axis indicates the vertical direction, and the X-axis... The Y-axis indicates the horizontal direction. Note that the above diagrams schematically represent the arrangement of each part. This does not accurately represent the ratio of the dimensions of each part.

[0008] The electrostatic chuck 10 is a device that attracts and holds an object by electrostatic attraction, for example, a semi-electrostatic chuck. It is used to fix the wafer W, which is the object to be manufactured, inside the vacuum chamber of a conductor manufacturing apparatus. The electrostatic chuck 10 comprises a ceramic part 20, a base part 30, and a joint part 40. These are the ceramic part 20, the joint part 40, and the base, oriented in the direction of the -Z axis (vertically downward). The parts are stacked in the order of section 30. The electrostatic chuck 10 in this embodiment is referred to as a "holding device". They also call them that.

[0009] The ceramic part 20 is a roughly circular plate-shaped member, and is made of ceramic (for example, aluminum oxide). It is formed mainly from aluminum (such as aluminum nitride). In this specification, the specific The phrase "it is the main component" or "it is the main forming material" refers to the content of the specific component in question. However, this means that it is 50% by volume or more. The diameter of the ceramic part 20 is, for example, 50 mm. A length of around 500mm is sufficient, and typically it is around 200mm to 350mm. The thickness of the part 20 should be, for example, about 1 mm to 10 mm. The ceramic part 20 is It is also called the "plate-like part".

[0010] As shown in Figure 2, an adsorption electrode 22 is placed inside the ceramic part 20. The electrode 22 is formed from a conductive material such as tungsten or molybdenum. When a voltage is applied to the adsorption electrode 22 from a power source (not shown), an electrostatic attraction force is generated. This electrostatic attraction causes the wafer W to be adsorbed and fixed to the mounting surface 24 of the ceramic part 20. The electrode 22 may be bipolar or unipolar. Also, the ceramic part 20 Inside, there is a resistive generator formed by a conductive material (e.g., tungsten or molybdenum). A heating element, not shown, is used to heat the wafer W which is adsorbed and fixed to the mounting surface 24. A heater electrode may be provided.

[0011] The base portion 30 is a plate-like member made of metal and formed in a substantially circular shape. For example, aluminum, magnesium, molybdenum, titanium, tungsten, nickel It may contain at least one of our metals: molybdenum, titanium, tan. Gusten has a relatively small coefficient of thermal expansion among the metals mentioned above, therefore, among these, When the base portion 30 is constructed using one type of metal, the base portion 30 and the ceramic portion It is desirable to be able to suppress the difference in thermal expansion coefficient between 20 and 20. The term "coefficient of thermal expansion" refers to the "coefficient of linear expansion." Also, magnesium has a relatively small Young's modulus. Therefore, when magnesium is used to construct the base portion 30, the thermal response generated in the base portion 30 It is desirable that the force can be reduced. Also, aluminum has a relatively high thermal conductivity, It is easy to manufacture and low-cost. Therefore, when aluminum is used to construct the base part 30 In addition, the cooling efficiency of the ceramic part 20 and the wafer W by the base part 30 is increased. This is desirable as it reduces the manufacturing cost of the electrostatic chuck 10. From the perspective of improving cooling efficiency while keeping manufacturing costs down, the metal content in the base part 30 A higher proportion is desirable, and it is desirable that the base portion 30 be mainly composed of metal. , containing 90% or more by mass of highly versatile aluminum (for example, A6061, A5 It is preferable that the base portion 30 be made of an aluminum alloy such as 052. It may contain non-metallic components such as ceramics. The diameter of the base part 30 is, for example, A range of approximately 220mm to 550mm is sufficient, and typically it is between 220mm and 350mm. The thickness of the base portion 30 can be, for example, about 20mm to 40mm. It is also called the "cooling section".

[0012] Multiple refrigerant flow paths 32 are formed inside the base portion 30 so as to follow the XY plane. By flowing a refrigerant such as a fluorine-based inert liquid, water, or liquid nitrogen through the refrigerant flow path 32, The base portion 30 is cooled. Then, the base portion 30 and the ceramic portion are connected via the joint portion 40. The ceramic part 20 is cooled by heat transfer between it and the 20, and the mounting surface 24 of the ceramic part 20 The held wafer W is cooled. This enables temperature control of the wafer W. In addition to a configuration in which the refrigerant flow path 32 is located inside the s section 30, the base section 30 is located outside the base section 30. The base portion 30 may be given a cooling function by cooling it.

[0013] The joint 40 is positioned between the ceramic part 20 and the base part 30, and the ceramic part 2 The opposing surfaces of 0 and the base portion 30 are joined. The joint portion 40 contains a silicone adhesive. Furthermore, it also contains surface-coated aluminum nitride particles. The thickness of the joint 40 is, for example, The particle size can be approximately 0.1 mm to 1.0 mm. Contains surface-coated aluminum nitride particles. The configuration of the joint 40 will be explained in detail later.

[0014] The electrostatic chuck 10 is further provided with multiple gas supply passages 50. 50 is provided penetrating the ceramic part 20, the joint part 40, and the base part 30 in the Z direction. It is located at a gas outlet 52 formed on the mounting surface 24 (see Figure 1). The gas supply line 50 supplies an inert gas, such as helium gas, from a gas supply device (not shown). The gas is supplied and an inert gas is discharged from the gas outlet 52 into the space between the mounting surface 24 and the wafer W. It supplies heat. This improves the heat transfer between the ceramic part 20 and the wafer W, The controllability of the temperature distribution of HW is further improved. Note that the gas supply path 50 is not essential, and static The electric chuck 10 may be configured without a gas supply passage 50.

[0015] B. Composition of the joint: The configuration of the joint 40 will be described below. As previously mentioned, the joint 40 is made of silicone It contains a cone-type adhesive and also contains surface-coated aluminum nitride particles. Because the elastic modulus of the ion-based adhesive is relatively low, it has the function of mitigating the thermal stress generated at the joint 40. Because it is high in temperature and has a relatively high heat resistance temperature, it is an excellent resin for forming the joint 40. Surface-coated aluminum nitride particles are aluminum nitride particles with an acid coating on their surface. A compound containing an element (hereinafter also referred to as "oxygen-containing aluminum compound") These are particles with a covering layer, for example, particles with an average particle diameter of 0.1 to 50 μm. And the surface-coated aluminum nitride particles of this embodiment are oxygen-containing aluminum By providing a coating layer containing a compound on the surface, the outermost surface of the surface-coated aluminum nitride particles The atomic ratio of oxygen atoms to aluminum atoms (hereinafter also referred to as the "O / Al value") However, it is between 1.4 and 4.0. With this configuration, this implementation The morphological joint 40 ensures low thermal resistance, as well as high flexibility and durability.

[0016] Examples of oxygen-containing aluminum compounds in the coating layer of surface-coated aluminum nitride particles include For example, aluminum oxide (α-alumina: α-Al2O3), aluminum phosphate (AlP O4), β-alumina, γ-alumina, YAG(Y3Al5O 12 ), or Lantern These can be used as luminates (LaAlO3), or as mixtures thereof. Oxygen-containing aluminum compounds have relatively high thermal conductivity. Specifically, such oxygen-containing aluminum compounds... Aluminum compounds are used, for example, to enhance the water resistance of aluminum nitride particles. A compound conventionally known as silicon dioxide (silicone) is used to constitute the coating layer applied to luminium particles. It exhibits a higher thermal conductivity than the heat transfer coefficient of SiO2 (1.38 W / (m·K)). For example, For example, the thermal conductivity of α-Al2O3 is 30 W / (m·K), while the thermal conductivity of YAG is 10 The coefficient of heat transfer is W / (m·K), and the heat transfer coefficient of lanthanum aluminate is 11 W / (m·K). Here, the thermal conductivity of the material constituting the coating layer is the thermal conductivity of aluminum nitride (150~20 If it is lower than 0 W / (m·K), the thermal conductivity of the surface-coated aluminum nitride particles is lower than that of aluminum nitride. It may be lower than the thermal conductivity of aluminum. However, as mentioned above, oxygen-containing aluminum By using a nitrium compound to form a coating layer of surface-coated aluminum nitride particles, This makes it possible to suppress the decrease in thermal conductivity caused by applying a coating layer to aluminum oxide particles. ru.

[0017] Furthermore, if the above-mentioned oxygen-containing aluminum compound is included in the coating layer, the surface coating nitride Hydroxyl groups become present on the surface of the luminium particles. As a result, the surface is coated with aluminum nitride. The polarity of the surface of the nium particles and the silicone adhesive becomes similar, resulting in good adhesion. Therefore, the surface of the aluminum nitride particles contains the oxygen-containing aluminum compound described above. By providing a coating layer containing a substance and setting the O / Al value to 1.4 or higher and 4.0 or lower, nitrogen A similar effect was obtained in aluminum oxide particles to improve wettability with silicone adhesives. This is possible when using a silane coupling agent together with a silicone adhesive. The silane coupling agent readily bonds with the hydroxyl groups on the surface of the surface-coated aluminum nitride particles. Therefore, the compatibility between the silicone adhesive and the surface-coated aluminum nitride particles is even better. It will become.

[0018] Surface-coated aluminum nitride particles having a coating layer composed of α-alumina are nitrided It can be produced by subjecting aluminum particles to an oxidation treatment. The above oxidation treatment is Under an oxygen-containing atmosphere (e.g., in air or water vapor), at a temperature of 600-1000°C. The aluminum nitride particles can be heated as shown below. Oxidation treatment can be performed on aluminum nitride Surface-coated aluminum nitride when the surface of aluminum particles is completely coated with alpha-alumina. The theoretical value of the O / Al ratio in a particle is 1.5.

[0019] Surface-coated aluminum nitride particles having a coating layer composed of aluminum phosphate This can be produced by subjecting aluminum nitride particles to phosphoric acid treatment. For example, phosphate treatment involves dispersing aluminum nitride particles in a solvent and then adding inorganic phosphoric acid to the dispersion. A process in which a substance is added dropwise, reacted under temperature conditions of room temperature to approximately 80°C, and then the solvent is evaporated. This can be done. The inorganic phosphate compound used is, for example, phosphoric acid (orthophosphate: H3 PO4), pyrophosphate, polyphosphate, phosphorous acid, hypophosphorous acid, metaphosphate and these It can be a mixture. Furthermore, the above phosphoric acid treatment separates aluminum nitride particles in a solvent. After adding an organophosphate compound dropwise to the dispersed solution, the mixture was processed under temperature conditions of 150-800°C. This can be done by heating.

[0020] Aluminum nitride particles are subjected to the phosphoric acid treatment described above, and aluminum phosphate When a coating layer composed of these elements is formed, the O / Al value exceeds 4.0. This is because phosphorus After the acid treatment, the surface of the surface-coated aluminum nitride particles is treated with the phosphoric acid used in the phosphoric acid treatment. This is because the compound remains. Such surface-coated aluminum nitride particles treated with phosphoric acid When further heat treatment is performed at a temperature of 100 °C or higher (for example, about 300 °C), the phosphoric acid compound remaining on the surface-coated aluminum nitride particles is removed, and at the same time, a reaction proceeds in which a part of the aluminum phosphate constituting the coating layer becomes aluminum oxide (mainly α-alumina). The amount of phosphoric acid compound removed and the amount of aluminum oxide generated can be increased by the degree of heat treatment after phosphoric acid treatment (at least one of increasing the heating time and increasing the heating temperature). As a result, the O / Al value gradually decreases from a value exceeding 4.0 and approaches 1.5. At this time, by performing heat treatment so that the O / Al value becomes 4.0 or less, the phosphoric acid compound remaining on the surface of the surface-coated aluminum nitride particles can be sufficiently removed. The degree of heat treatment after phosphoric acid treatment (at least one of increasing the heating time and increasing the heating temperature) The O / Al value can be increased. 4.0 and gradually becomes smaller, approaching 1.5. At this time, by performing heat treatment so that the O / Al value becomes 4.0 or less, the phosphoric acid compound remaining on the surface of the surface-coated aluminum nitride particles can be sufficiently removed.

[0021] In the electrostatic chuck 10 of the present embodiment, the thermal resistance of the joint portion 40 is desirably 5.0×10 <0附图说明(m 2 The thermal resistance of the joint portion 40 is preferably 3.5×10 -4 (m 2 K / W) or less, more preferably 2.5×10 -4 (m 2 K / W) or less is even more desirable. Here, the thermal conductivity λ and the thermal resistance R refer to the values at room temperature (22 °C). When the thermal resistance of the joint portion 40 is R (m K / W), the thickness of the joint portion 40 is t (m), 2 and the thermal conductivity of the joint portion 40 is λ (W / (m·K)), the thermal resistance R of the joint portion 40 is obtained by the following (1) formula.

[0022] R (m2 K / W)=t(m)÷λ(W / (m·K)) …(1)

[0023] By setting the thermal resistance of the joint 40 to the above value, the base portion 30 and the joint 40 are connected. Heat transfer between the ceramic part 20 and the base part 30, that is, heat transfer from the ceramic part 20 to the base part 30. This makes it easier to perform the operation and improves the cooling efficiency of the electrostatic chuck 10.

[0024] The thermal resistance of the joint 40 can be reduced by reducing the thickness of the joint 40, according to equation (1). This is possible. For example, the thickness of the joint 40 is preferably 500 μm or less. By making it 400 μm or less, the thermal resistance of the joint 40 is reduced to 5.0 × 10 -4 (m 2 (K / W) The following will become easier. However, the thickness of the joint 40 must not exceed the above value. For example, if you want to increase the thermal conductivity of the joint 40, you can increase the thickness of the joint 40 to 400μm. Even if m is greater than that, the thermal resistance of the joint 40 is 5.0 × 10 -4 (m 2 Keep it below kW This becomes relatively easy. The thickness of the joint 40 is, for example, related to the flexibility and strength of the joint 40. From the perspective of ensuring accuracy, a thickness of 50 μm or more is sufficient.

[0025] The thermal resistance of the joint 40 can be increased by increasing the thermal conductivity of the joint 40, as shown in equation (1). It can be made smaller. One way to increase the thermal conductivity of the joint 40 is as described above. Thus, the coating layer of surface-coated aluminum nitride particles is made of oxygen-containing aluminum with higher thermal conductivity. One method involves constructing it with a nium compound. In addition, it is possible to increase the thermal conductivity of the joint 40. One such method is the content ratio of surface-coated aluminum nitride particles in the joint 40. Methods to improve this can be listed. Surface coating aluminum nitride particles in the joint 40 The content should preferably be 60% by mass or more, and more preferably 70% by mass or more. Preferably, it is even more desirable to have 80% by mass or more. For example, the table in the joint 40. By setting the content of surface-coated aluminum nitride particles to 70% by mass or more, the heat of the joint 40 It becomes easier to achieve a conductivity of 0.8 W / (m·K) or higher.

[0026] Furthermore, the higher the proportion of inorganic filler in the joint 40, the greater the amount of inorganic filler in the joint 40. The amount of strain at maximum shear stress tends to be small. The amount of strain at maximum shear stress is the amount of contact This is a numerical value that serves as an indicator of the flexibility and stress relaxation performance of the joint 40, and represents the strain at maximum shear stress. A larger quantity indicates better flexibility and stress relaxation performance of the joint 40. The amount of strain under shear stress will be explained in detail later. In this way, at the joint 40 The higher the proportion of inorganic filler, the greater the strain at maximum shear stress in the joint 40. The reason why it becomes smaller is that the higher the proportion of inorganic filler, the more the inorganic filler is contained in the surrounding resin. The degree to which the resin composition is restrained increases, and the flexibility of the joint 40 decreases, This is thought to be because it becomes less susceptible to strain. Therefore, when the maximum shear stress occurs at the joint 40, From the viewpoint of suppressing the amount of condensation and ensuring flexibility, the surface coating aluminum nitride of the joint 40 The content of microparticles should preferably be 90% by mass or less.

[0027] The lower limit of the thermal resistance of the joint 40 is, for example, 0.6 × 10 -4 (m 2 (K / W) This can be done. In order to reduce the thermal resistance of the joint 40, an inorganic filler is constructed as described above. One possible approach is to appropriately select the materials and increase the proportion of inorganic fillers. However, if the proportion of inorganic filler is increased excessively, the flexibility of the joint 40 will be impaired. There is a possibility that this may occur. Also, in order to reduce the thermal resistance of the joint 40, the joint 40 may be made thinner. One possible method is to make the joint 40 excessively thin. As the joint decreases, it may become difficult to ensure the flexibility of the joint 40. The thermal resistance of part 40 is 0.6 × 10 as described above. -4 (m 2 It is desirable to set it to kW or higher. .

[0028] Furthermore, the thermal resistance of the joint 40 depends on the shape of the inorganic filler particles contained in the joint 40. It can be changed. In order to reduce the thermal resistance of the joint 40, the inorganic filler is cut off. When viewed from the surface, if the radius of the inscribed circle is R1 and the radius of the circumscribed circle is R2, then "R2 / R It is desirable that the average value of "1" be 1.05 or higher, and even better if it is 1.10 or higher. Desirable. The closer "R2 / R1" is to 1.0, the closer the particle shape is to a perfect sphere (in the following, true This indicates a high degree of accuracy (also known as a high degree of ball-scoring).

[0029] The methods for identifying the inscribed and circumscribed circles, and for finding "R2 / R1", are as follows: That is, in the image obtained by observing the cross-section of the joint 40 with a scanning electron microscope (SEM), We focus on one particle that is observed. Then, we examine the three peaks within the particle that contain the particle we are focusing on. Draw a circle so that it is tangent to the point, and call this the circumscribed circle. Also, what is enclosed within the particle and outside the particle Draw a circle that touches the circumference in three places, and call this the inscribed circle. If multiple circles can be drawn, draw the circle The circle with the smallest radius is defined as the inscribed circle and circumscribed circle. Similarly, for 20 particles, the inscribed circle... Identify the circumscribed circle and measure the radius R1 of the inscribed circle and the radius R2 of the circumscribed circle, and take the average value. Calculate "R2 / R1" from this.

[0030] Figure 3 shows how to determine the "R2 / R1" ratio when viewing the inorganic filler 42 particles in cross-section. Figure 4 is an explanatory diagram showing how heat transfer paths are formed between the inorganic fillers 42. In Figure 3, the inscribed circle of the inorganic filler 42 when viewed in cross-section is shown by a dashed line, and the circumscribed circle is shown by It is shown by a dashed line. Furthermore, the center of the inscribed circle is shown as O1, and the center of the circumscribed circle is shown as O2. This is shown in Figure 4. In Figure 4, heat conduction paths are formed at the points where the inorganic fillers 42 come into contact with each other. The appearance is represented by double-headed arrows. The "R2 / R" when viewing the inorganic filler 42 in cross-section. The value of "1" is greater than or equal to the lower limit mentioned above, and the shape of the inorganic filler 42 is different from a perfect sphere on the surface. The more uneven the surface, the more contact points there are between the inorganic fillers 42, as shown in Figure 4, resulting in bonding. Heat conduction paths are more easily formed within part 40, and the thermal resistance of the joint part 40 is reduced. The value of "R2 / R1" can be adjusted by modifying the manufacturing method of aluminum nitride particles, or This can be modified in various ways by applying a treatment to the aluminum nitride particles to increase their sphericity. That is the case.

[0031] Furthermore, in this embodiment, the strain amount at the maximum shear stress of the joint 40 is 0.5 mm or less. It is desirable to have the above. The strain amount at maximum shear stress of the joint 40 should be 1.0 mm or more. It is more desirable to do so, and even more desirable to make it 1.3 mm or more. Note that joint 4 The strain at maximum shear stress is usually 5.0 mm or less. As previously mentioned, "strain amount" is an indicator that represents the flexibility and stress relaxation performance of the joint 40. This value represents the maximum shear stress generated at the joint 40 when a shear force is applied to the joint 40. When this occurs, that is, when the maximum shear stress occurs at the joint 40, This refers to the magnitude of the shear strain (the amount of displacement in the direction of the shear force). The amount of strain at maximum shear stress is large. This indicates that the joint 40 has high flexibility. The amount of strain at maximum shear stress was measured. The specific measurement method using the tensile testing machine will be explained in detail later. Joint 40 If the strain amount at maximum shear stress is set to the above value, the flexibility and stress relaxation of the joint 40 will be improved. It becomes possible to ensure sufficient capacity.

[0032] Figure 5 is an explanatory diagram regarding the stress generated at the joint 40. When using the electrostatic chuck 10. Due to heat input to the ceramic part 20, such as exposure to plasma, the ceramic Part 20 is heated and expands. The base part 30 is cooled by the refrigerant flow path 32. It then shrinks. Figure 5 shows the ceramic part 20 being heated and expanding, and the base The white arrows indicate how part 30 cools and shrinks. At this time, the joint part 40 In this case, a tensile force acts on the ceramic part 20 and the base part 30. Figure 5 shows the joint. The force with which part 40 pulls on the ceramic part 20, and the force with which part 30 pulls on the base part, respectively The arrows indicate this. Furthermore, in Figure 5, the amount of displacement in the X-axis direction that occurs in the joint 40 is shown as strain. It is shown as the quantity δ.

[0033] Furthermore, in the electrostatic chuck 10, the base portion 30 is generally larger than the ceramic portion 20. It has a high coefficient of thermal expansion and expands and contracts significantly with temperature changes. Therefore, depending on the temperature conditions... Therefore, the amount of thermal expansion of the base portion 30 is greater than the amount of thermal expansion of the ceramic portion 20. It may also become larger. In this way, expansion and contraction may occur between the ceramic part 20 and the base part 30. Due to the difference in degree of contraction, a shear force in the X-axis direction is applied to the joint 40, and shear Stress is generated. Therefore, as described above, the amount of strain at the maximum shear stress of the joint 40 is large. By increasing the width, even when a large shear force is applied to the joint 40, This reduces the shear stress generated at the joint 40 and minimizes damage to the joint 40.

[0034] Figure 6 shows how the joint 40 stretches when shear stress is generated in the joint 40. This is an explanatory diagram. The joint 4 contains an inorganic filler such as surface-coated aluminum nitride particles. The amount of strain at maximum shear stress of 0 is due to the high flexibility of the adhesive (resin) that makes up the joint 40. The better the adhesion between the adhesive and inorganic filler that make up the joint 40 (the better the wettability) The more flexible it is, the larger it becomes. In this embodiment, the adhesive that constitutes the joint 40 is flexible. It uses a superior silicone-based adhesive. Furthermore, it uses oxygen-containing aluminum as an inorganic filler. Surface-coated aluminum nitride particles with a coating layer containing a nium compound are used. The surface-coated aluminum nitride particles have good wettability with silicone-based adhesives, which are oxides. It is suitable and has good compatibility with silicone-based adhesives. Therefore, the maximum size of the entire joint 40 The amount of strain increases under sectional stress. Figure 6 shows a bonding agent containing an inorganic filler with good wettability. (a) shows how shear stress is applied to the joint 40, and the inorganic film has insufficient wettability. Figure 6 shows (b) how shear stress is applied to the joint 40 including the r. As shown, if the wettability of the inorganic filler is insufficient, the adhesive will not be flexible. Even if the adhesive stretches due to shear stress, at the interface between the adhesive and the inorganic filler... Because fracture is more likely to occur, the amount of strain at maximum shear stress decreases.

[0035] Furthermore, the amount of strain at maximum shear stress in the joint 40 can be increased by increasing the thickness of the joint 40. Therefore, it can also be made larger. Also, as previously mentioned, the inorganic filler in the joint 40 The higher the proportion of -, the smaller the strain at maximum shear stress in the joint 40 tends to be. be.

[0036] The joint 40 adjusts the properties of the joint 40 and the properties of the paste used to form the joint 40. As a filler (inorganic filler) for this purpose, other fillings other than surface-coated aluminum nitride particles It may further contain fillers. Other fillers mentioned above include, for example, aluminum oxide. Alumina (Al2O3), Zirconium Oxide (ZrO2), Ix Oxide Yttria (Y2O3), yttrium fluoride (YF3), aluminum nitride ( AlN), silicon carbide (SiC), silicon nitride (Si3N4), silicon dioxide (silica: SiO2), iron oxide, barium sulfate, calcium carbonate, etc. can be used. Joint 4 The content of the above-mentioned other fillers in 0 is such that the joint 40 contains surface-coated aluminum nitride particles. The impact on the effect of possessing it must be within an acceptable range.

[0037] Furthermore, the joint 40 also contains a catalyst that promotes the curing reaction of the adhesive, and promotes curing and bonding. To provide adhesion, silane coupling agents, crosslinking agents, and adhesives are used to adjust the curing speed. It may also contain reaction inhibitors or viscosity modifiers.

[0038] According to the electrostatic chuck 10 of this embodiment configured as described above, the electrostatic chuck 10 The joint 40 comprises a silicone adhesive and surface-coated aluminum nitride particles, The atomic ratio of oxygen atoms to aluminum atoms at the outermost surface of surface-coated aluminum nitride particles The O / Al value is between 1.4 and 4.0. By setting this to 1.4 or higher, the oxide is formed on the surface of the surface-coated aluminum nitride particles. The wettability between the silicone adhesive and the joint 40 can be improved. In this, it becomes possible to achieve sufficient flexibility to stretch when shear stress occurs, and the joint This makes it possible to suppress problems caused by stress in part 40, such as damage to the joint 40. Furthermore, the inclusion of surface-coated aluminum nitride particles results in high heat transfer at the joint 40. This enables improved conductivity and enhances the cooling performance of the electrostatic chuck 10. Specifically, the maximum shear stress strain of the joint 40 is set to 0.5 mm or more, and the joint This makes it easy to achieve a thermal conductivity of 0.8 W / (m·K) or higher for the joint 40.

[0039] Such effects are particularly pronounced when the electrostatic chuck 10 is exposed to higher-power plasma. As shown above, this effect is particularly noticeable when the heat input to the ceramic part is large. Even without providing heater electrodes for heating the buck section 20, high plasma power When using the electrostatic chuck 10 together with the ceramic part 20, the mounting surface of the ceramic part 20 and the base part 30 Because the temperature difference between the two points tends to become large, the effects of this embodiment are significantly enhanced.

[0040] Furthermore, according to this embodiment, as described above, the O / Al value is 4.0 or less, so static During use of the electric chuck 10, etc., substances contained in the coating layer volatilize into the plasma atmosphere. This helps to suppress contamination of target objects such as wafers W. The O / Al value is 4 If it is 0 or less, the substance that may be the source of contamination is contained in the material used to form the coating layer. For example, when using aluminum phosphate as an oxygen-containing aluminum compound, This is because it is believed that phosphoric acid and other phosphate compounds used in the acid treatment have been removed.

[0041] C. Other embodiments: This disclosure applies to holding devices other than electrostatic chucks that hold wafers W using electrostatic attraction. It is also possible to do so by joining a plate-like part, a cooling part (base part), and the plate-like part and the cooling part. A joint and another holding device that holds an object on the surface of a plate-like part, for example, CVD, This can also be applied to heater devices for vacuum equipment such as PVD and PLD, as well as vacuum chucks. .

[0042] Furthermore, in each of the embodiments described above, the plate-like portion having a mounting surface is made mainly of ceramic. Although the ceramic part 20 is used, the plate-like part will mainly consist of materials other than ceramic. This is also acceptable. Even with such a configuration, by applying the configuration of the present disclosure illustrated in the embodiments, Furthermore, by improving the cooling performance of the holding device, stress generated at the joint is suppressed, and at the joint A similar effect can be obtained in suppressing problems caused by the resulting stress. [Examples]

[0043] The holding device of this disclosure will be described below based on examples. Here, O / A As various samples with different values ​​of l, thermal resistance of the joint, and strain at maximum shear stress, etc. Sheet-like samples, from sample S1 to sample S9, were prepared. The electrostatic chuck 1 of the embodiment shown in Figure 2 has a joint with the same composition as samples S1 to S9. A sample of an electrostatic chuck with the same configuration as 0 was fabricated. Below, the electrostatic chuck... For the morphological sample, the same composition as the sheet-like sample having the same composition as the joint is also used. They are called by their pull number.

[0044] Figure 7 shows the O / Al values ​​of the surface-coated aluminum nitride particles present in each sample, "R2 / The value of "R1", and the thickness of the joint, thermal resistance, and the content of aluminum nitride particles in the surface coating. Along with the strain amount at maximum shear stress and the value of thermal conductivity, the cooling of the ceramic part through the joint is also measured. The results of evaluating the thermal response, which represents performance, and the susceptibility of the joint to damage (delamination) were shown below. This is an explanatory diagram that summarizes the information.

[0045] <Preparation of each sample> Below, we will first describe the sheet-like sample and electrostatic chuck form common to each sample. The sample preparation method will be explained, followed by a description of the materials and preparation conditions for each sample. Samples S1 to S9 all consist of a silicone-based adhesive mixed with an inorganic filler. It is equipped with a joint.

[0046] [Preparation of inorganic fillers] Samples S1-S5 are composed of an oxygen-containing aluminum compound as an inorganic filler. Using aluminum nitride particles (surface-coated aluminum nitride particles) which have a coated layer formed thereon Samples S6-S8 consist of aluminum nitride particles without a coating layer, used as an inorganic filler. Sample S9 was used. The sample S9 was composed of silicon dioxide as an inorganic filler. Aluminum nitride particles with a covering layer were used.

[0047] The aluminum nitride particles are powder manufactured by Toyo Aluminum with an average particle size of 15.0 μm. The following was used: Aluminum nitride used in samples S1-S3 and samples S6 and S7. The particles are subjected to a 72-hour nylon ball milling process in a solvent to make their shape closer to a perfect sphere. They did that.

[0048] In samples S1-S3 and sample S5, aluminum nitride particles were prepared using a mixer. The material was mixed with phosphoric acid, and the surface of the aluminum nitride was coated with phosphoric acid (phosphoric acid treatment). After that, heat treatment is performed at a temperature of 100°C or higher, and phosphate aluminum is applied to the surface of the aluminum nitride particles. A coating layer was formed by creating a phosphate layer. The resulting powder was washed with pure water and aluminum phosphate was used. Surface-coated aluminum nitride particles having a coating layer were obtained. The surface-coated aluminum nitride particles of samples S1-S3 and sample S5 possess The coating layer is thought to contain α-alumina in addition to aluminum phosphate.

[0049] In sample S4, aluminum nitride particles were heat-treated (oxidized) at 800°C in an air atmosphere. ) was performed to form a coating layer of α-alumina on the particle surface. In sample S9, aluminum nitride The nium particles were mixed with tetraethoxysilane in a solvent, and after removing the solvent, the temperature was raised to over 150°C. The material was heat-treated at the specified temperature. Afterwards, it was thoroughly cleaned and coated with a silicon dioxide layer. Aluminum nitride particles were obtained.

[0050] [Preparation of sheet-like samples] The method for preparing the sheet-like sample is as follows: Silicone-based adhesive before curing, In addition to inorganic fillers for each sample, silane coupling agents, crosslinking agents, and catalysts are used. The mixture was added and mixed to obtain a varnish-like silicone adhesive composition (adhesive paste). The same type of cone-type adhesive was used in common for samples S1 to S9. The adhesive paste was formed into a sheet shape using the doctor blade method. By changing the conditions of the molding machine that applies adhesive paste using a blade, a sheet-like shape can be formed. The sample thickness was varied depending on the sample. The adhesive paste in sheet form was kept below 100°C. It was heat-treated at [temperature] and partially cured.

[0051] [Preparation of electrostatic chuck-type samples] The electrostatic chuck sample was prepared using the semi-cured adhesive paste described above, and then the ceramic It was manufactured by joining the backing part (plate-shaped part) and the base part (cooling part). Ceramic part It was prepared as follows: First, using a conventionally known method, an alumina was prepared Multiple ceramic green sheets were fabricated. Then, on the ceramic green sheet... Heaters, adsorption electrodes, vias, and ventilation holes are formed in these ceramic green sheets. The layers are laminated, heat-pressed together, and fired at 1400-1600°C in a reducing atmosphere to produce a 50mm thick piece. The ceramic part was obtained. Next, the semi-cured adhesive paste described above was applied to the ceramic part and the base By placing it between the parts and then heat-curing the adhesive paste, the electrostatic chuck A morphological sample was obtained.

[0052] [Samples S1-S5] As previously described, samples S1 to S5 use aluminum nitride as an inorganic filler for surface coating. It was prepared using um particles. When preparing the adhesive paste described above, the silicone before curing was used. The mixing ratio of the adhesive system and the surface-coated aluminum nitride particles was varied depending on the sample. Therefore, as shown in Figure 7, the content ratio of surface-coated aluminum nitride particles in the joint The particle content varies depending on the sample. Specifically, the particles in sample S1... The content ratio is 60% by mass, and the particle content ratio of sample S2 is 70% by mass, The particle content ratio of S3 to S5 was 80% by mass. Furthermore, the thickness of the sheet-like sample was... By making them different, the thickness of the joint of each sample is 500 μm for sample S1, and 500 μm for sample S1. Pull samples S2 and S4 were 300 μm, while samples S3 and S5 were 200 μm.

[0053] [Samples S6-S8] As previously described, samples S6-S8 are nitrides without a coating layer, using inorganic fillers. It was prepared using aluminum particles. Adhesive paste was also prepared for samples S6-S8. When manufacturing, the mixing ratio of the silicone adhesive and aluminum nitride particles before curing is measured in the sample. This is modified by the ru, and as a result, as shown in Figure 7, the aluminum nitride at the joint The proportion of particles (particle content) varies depending on the sample. Specifically, Sample S6 has a particle content of 30% by mass, while samples S7 and S8 have a particle content of 4% by mass. It was 6% by mass. Also, by varying the thickness of the sheet-like sample, each sample The thickness of the joint of the sample S6 is 300 μm, sample S7 is 400 μm, sample S8 was 600 μm.

[0054] [Sample S9] As described above, Sample S9 was prepared using aluminum nitride particles having a coating layer composed of silicon dioxide (silica: Si O2). The particle content ratio of Sample S9 was 46% by mass, and the thickness of the joint was 500 μm.

[0055] <Measurement of O / Al value> The O / Al value was measured by analyzing the surface of the inorganic filler (surface-coated aluminum nitride particles having a coating layer composed of an oxygen-containing aluminum compound, aluminum nitride particles without a coating layer, or aluminum nitride particles having a coating layer composed of silica), which is the material for producing each sample, by X-ray photoelectron spectroscopy (XPS: X-ray Photoelectron Spectroscopy) to identify the elements constituting the outermost surface of the inorganic filler. Specifically, for all compounds containing aluminum, the composition ratio was calculated from the peak area and the O / Al value was calculated.

[0056] <Measurement of thermal conductivity> FIG. 8 is an explanatory diagram showing an outline of the procedure for measuring the thermal conductivity of the joint. When measuring the thermal conductivity of the joint, first, for each sample in the form of the electrostatic chuck 10, an arbitrary location was cut out in the X-Y direction with a size of 50 mm × 50 mm and penetrated in the thickness direction (Z direction) (from (A) in FIG. 8 to (B) in FIG. 8), and the portion of the joint 40 was cut out from the obtained test piece with a cutter (from (B) in FIG. 8 to (C) in FIG. 8). In FIGS. 8(A) and 8(B ), the cut-out portion is shown surrounded by a dashed line. The joint cut out as shown in FIG. 8(C) was punched out with a diameter of 10 mm, and the thermal diffusivity was measured by the laser flash method Measurements were taken. In addition, using the cut-out joint as shown in Figure 8(C), the Archimedes method was used. The density of the joint was measured. Then, the thermal conductivity was calculated from the measured values ​​of thermal diffusivity and density. I took it out.

[0057] <Calculation of thermal resistance> To calculate the thermal resistance of the joint, for each sample of the electrostatic chuck 10, arbitrarily Cut out the area in the XY direction to a size of 50mm x 50mm (from (A) in Figure 8 to Figure 8) (B)) The thickness of the joint is measured by observing the cross-section of the obtained test specimen with an optical microscope. And the thickness of the joint measured in this way and the joint calculated as described above The thermal resistance of the joint was calculated from the thermal conductivity of the part. The thermal resistance was calculated using the equation (1) described above. It was calculated.

[0058] <Particle content ratio> Inorganic filler at the joint (a coating layer composed of oxygen-containing aluminum compounds) Aluminum nitride particles having a surface coating, aluminum nitride particles without a coating layer, (The content ratio of aluminum nitride particles having a coating layer made of silica) The content ratio was measured as follows: First, each sample in the form of an electrostatic chuck 10 was... Therefore, cut out an arbitrary area in the XY direction with dimensions of 50mm x 50mm (Figure 8 (A (Figure 8(B)) The joint portion 40 was removed from the obtained test piece with a cutter. Figures 8(B) to 8(C). After measuring the mass of the cut-out joint, the silicone The silicone resin was dissolved with a solvent, and the contained inorganic filler was collected. Measure the mass of the resin and calculate its ratio to the mass before the silicone adhesive was dissolved. This allowed us to calculate the particle content ratio at the joint.

[0059] <Calculation of R2 / R1> For each sample in the form of the electrostatic chuck 10, for calculating the value of "R2 / R1", any location was cut out in the X-Y direction with a size of 50 mm × 50 mm (from (A) in FIG. 8 to FIG. 8 (B)), and the portion of the joint 40 was taken out from the obtained test piece with a cutter (from (B) in FIG. 8 to (C) in FIG. 8). After mirror-polishing the cross-section of the cut-out joint, a scanning electron microscope (SEM) was used to observe, and for 10 inorganic filler particles observed in a field of view of 200 μm × 200 μm, their shapes were observed. Using the image analysis software WinROOF, the radius R1 of the inscribed circle and the radius R2 of the circumscribed circle were measured to obtain the value of "R2 / R1" (see FIG. 3) , and the value of "R2 / R1" for each sample was calculated as the average value of 10 particles.

[0060] <Measurement of strain amount at maximum shear stress> FIG. 9 is an explanatory diagram schematically showing the state of obtaining the strain amount at maximum shear stress. The strain amount at maximum shear stress is obtained by performing a tensile test to obtain the maximum shear stress as the maximum value of the shear stress and measuring the strain amount when the shear stress reaches the maximum shear stress. . FIG. 9(A) shows the state of the tensile test seen from the front, and FIG. 9(B) shows the state seen from the side. The test pieces 70 of samples S1 to S9 were prepared by attaching the semi-cured adhesive sheets of each sample to the portions of 25 mm × 12 mm from the ends of two aluminum plates 72 with a width of 25 mm and a length of 150 mm up to a position 12 mm, and bonding the two aluminum plates 72 in a direction where they can be pulled in opposite directions to each other, and then curing the above-mentioned semi-cured adhesive sheet. The thickness t of the test piece 70 at the start of the test is the thickness of the joint shown in FIG. 7. Yes. Next, the two aluminum plates 72 are placed relative to each other so that a shear force acts on the above test specimen. They were moved. Figure 9(B) shows the relative direction of movement of the two aluminum plates (shear direction). The area of ​​the test specimen before load transfer (25mm x 12mm) is indicated by a white arrow. The shear stress was calculated by dividing by ). The relative movement of two aluminum plates in this manner The motion was continued until the test specimen 70 fractured, and the shear stress at which the shear stress reached its maximum was measured. The maximum shear stress (in MPa) was used. The strain at maximum shear stress (in mm) was also used. In the tensile test shown in Figure 9, when the shear stress reached its maximum, the test specimen 70... This was defined as the displacement in the shear direction.

[0061] <Evaluation of heat dissipation response> For each sample S1 to S9 in the form of an electrostatic chuck, the thermal pull response (through the joint) The cooling performance of the ceramic portion was evaluated. Specifically, the initial temperature of the ceramic portion of each sample was evaluated. The temperature was set to 150°C and heated until the ceramic part reached 150°C. The base was cooled by supplying 30°C refrigerant to the refrigerant flow path. Then, the ceramic part was 15 After reaching 0°C, heating of the ceramic part is stopped, and the surface of the ceramic part is examined using a thermal camera. While measuring the temperature, we also measured the time it took for the ceramic surface to cool to 40°C. If it takes longer than 500 seconds for the ceramic part to cool to 40°C, then heat dissipation will be performed. If the response is evaluated as low (×) and less than 300 seconds, the thermal response is very good. It was rated as present (◎). The time it takes for the ceramic part to cool to 40°C is less than 300 seconds. If the duration is long, but less than 400 seconds, the thermal response is evaluated as excellent (○), and if it is 400 seconds or longer, For longer durations, such as 500 seconds or less, the thermal response was evaluated as good (△).

[0062] <Evaluation of delamination at joints> Peel tests were performed on each sample S1 to S9 in the form of an electrostatic chuck, and the degree of peeling at the joint was determined. An evaluation was conducted. Specifically, each sample was placed in a commercially available thermal cycle tester and subjected to a maximum temperature of 15°C. A thermal cycling test was performed 100 times at 0°C, with a minimum temperature of 0°C, and then returned to room temperature. The presence or absence of delamination at the joint between the lock and base parts was evaluated. The absence of defects was determined using a known ultrasonic flaw detection device. Ultrasound was irradiated from the ceramic part side, and Reflected echoes (scratch echoes) were detected from a depth corresponding to the bonding interface between the lamination and the joint. It was determined that there was delamination at the bonding interface between the ceramic part and the joint. Ultrasound was used on the base part side. Irradiation is performed, and reflected echoes (scratch echoes) are detected from a depth corresponding to the bonding interface between the base and the joint. Upon examination, it was determined that there was delamination at the joint interface between the base and the joint. If delamination is observed on at least one side of the surface, it is classified as "delamination present," and if delamination is not observed by ultrasonic testing, Those that did not peel were evaluated as "no peeling".

[0063] As shown in Figure 7, oxygen atoms and aluminum atoms at the outermost surface of surface-coated aluminum nitride particles When the atomic ratio of O / Al, which is the atomic ratio with nium atoms, is 1.4 or higher (Samples S1-S5) ), it was confirmed that the thermal response was rated as good (△) or better.

[0064] In contrast, when the O / Al value is less than 1.4, sufficient thermal response is required. Unsatisfactory performance was not achieved. As shown in samples S6-S8, aluminum nitride particles were covered If there is no covering layer, delamination will occur at the joint, and insufficient thermal resistance will be applied at the joint. The wettability of the aluminum nitride particles was not achieved. The wettability is inferior to that of aluminum nitride particles, and is inferior to that of silicone-based adhesives. This is thought to be due to insufficient compatibility with the carbon dioxide. Also, as shown in sample S9, When using aluminum nitride particles with a coating layer made of silicon, bonding No peeling occurred in the area, but the thermal response was poor. This is due to silicon dioxide The thermal conductivity of the coating layer composed of an oxygen-containing aluminum compound This is thought to be because it is lower compared to the heat transfer coefficient.

[0065] Furthermore, as shown in Figure 7, in addition to the fact that the O / Al value is 1.4 or higher (Sample S1) Furthermore, by reducing the thickness of the joint (to 400 μm or less), the thermal resistance of the joint is reduced to 5.0 × 10 -4 m 2 By setting it below K / W (Sample S2), the thermal response is further improved. This was confirmed. Here, in the evaluation results of the thermal response shown in Figure 7, sample S2 and Sample S3 is described as having excellent thermal response (○), but thermal The time required for cooling after stopping the heating used to evaluate the responsiveness was higher for sample S3 than for Sun. It was shorter than Pull S2. In other words, it had a higher particle content (for example, 70% by mass or more). It was confirmed that the thermal response improved by doing this. Also, sample S3 and sample As can be seen by comparing it with S5, the average value of the "R2 / R1" should be 1.10 or higher. This confirmed that the thermal response was further improved. Also, sample S4 and sample As can be seen by comparing with S5, in the coating layer of surface-coated aluminum nitride particles, oxidation Similar effects can be obtained even if the ratio of aluminum to aluminum phosphate differs. This was confirmed.

[0066] This disclosure is not limited to the embodiments described above, but may extend to the extent that it does not depart from the spirit thereof. It can be realized in various configurations. For example, in each of the embodiments described in the section on the summary of the invention... The technical features in the embodiments corresponding to the technical features solve some or all of the above-mentioned problems. For this purpose, or to achieve some or all of the effects described above, substitutions or combinations may be made as appropriate. It is possible to combine them. Furthermore, the technical features of this specification are not considered essential in this specification. If not explained, it can be deleted as appropriate. [Explanation of symbols]

[0067] 10…Electrostatic chuck 20…Ceramic part 22...Adsorption electrode 24… Mounting surface 30...Base section 32… Refrigerant flow path 40…Joint part 42… Inorganic fillers 50…Gas supply lines 52...Gas outlet 70…Test piece 72…Aluminum plate

Claims

1. A holding device for holding an object, A plate-like portion formed in a plate shape, A cooling section formed in a plate shape to cool the plate-shaped portion, A joint is provided between the plate-like portion and the cooling portion, and joins the opposing surfaces of the plate-like portion and the cooling portion. Equipped with, The joint comprises a silicone adhesive and surface-coated aluminum nitride particles having a coating layer containing an oxygen-containing aluminum compound on its surface. The thermal conductivity of the joint is 0.8 W / (m·K) or higher. The maximum shear strain of the joint, obtained by dividing the maximum shear stress strain of the joint by the thickness of the joint before the measurement of the maximum shear stress strain, is 260% or more. When the surface-coated aluminum nitride particles are viewed in cross-section, let R1 be the radius of the inscribed circle and R2 be the radius of the circumscribed circle. The characteristic feature is that the average value of R2 / R1 is 1.10 or greater. holding device.

2. A holding device according to claim 1, The plate-like portion is characterized in that it is mainly composed of ceramic, includes an adsorption electrode for holding the object, and does not include a heater electrode for heating the object. holding device.

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