Electrostatic chuck

Abstract

An electrostatic chuck (1) comprises a dielectric layer (10) and a first resin layer (20) provided on the dielectric layer (10). The first resin layer (20) has a holding surface for holding a member to be held. The first resin layer (20) has an elastic modulus of 10-1000 MPa at 40°C in a region in contact with the dielectric layer (10).

Description

Electrostatic chuck

[0001] This application claims priority from Japanese Patent Application No. 2024-006083, filed on January 18, 2024, the contents of which are incorporated herein by reference.

[0002] When manufacturing semiconductor integrated circuits using semiconductor wafers or liquid crystal panels using insulating substrates such as glass substrates or films, it is necessary to adsorb and hold the substrate, such as the semiconductor wafer, glass substrate, or insulating substrate, at a predetermined location. An electrostatic chuck is used to hold the held member. In recent years, as the held members, such as semiconductor wafers and glass substrates, that are adsorbed and held by electrostatic chucks have become larger, there have been challenges in increasing the adsorption force of the electrostatic chuck and reducing particles on the back surface of the held member.

[0003] To solve the above problems, an electrostatic chuck device is known in which, for example, a holding member made of a resin material is provided on a base to protrude therefrom and is capable of attracting and holding a plate-shaped workpiece, and an electrostatic chuck having an attracting electrode therein is disposed lower than the holding member in at least a portion of a space formed between the plate-shaped workpiece and the base via the holding member, so that the electrostatic chuck electrostatically attracts the plate-shaped workpiece without contacting the plate-shaped workpiece (see, for example, Patent Document 1). In this electrostatic chuck device, the resin material constituting the holding member has an elastic modulus of 0.5 MPa or more and 10 MPa or less.

[0004] Also known is an electrostatic attraction member that includes a contact member made of a dielectric material and having a contact surface on a first side facing the surface of an object that can deform to conform to the surface of the object, and an electrode portion provided on a second side of the contact member opposite the first side and capable of applying a voltage to the contact member, the electrode portion including multiple layers of electrodes stacked with insulating layers sandwiched between them (see, for example, Patent Document 2). In this electrostatic attraction member, the contact member is made of a dielectric material that has elasticity and flexibility that allows it to deform to conform to the surface of the object.

[0005] International Publication No. 2012 / 026421 Japanese Patent Application Laid-Open No. 2023-37788

[0006] However, in the inventions described in Patent Documents 1 and 2, the durability (corrosion resistance) of the holding member (contact member) against corrosive gases and the property of preventing adhesion of contaminants (contamination resistance) are insufficient.

[0007] The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide an electrostatic chuck in which a holding member that holds a held member has excellent durability (thermal durability, corrosion resistance, etc.) and contamination resistance (low volatility, particle resistance, etc.).

[0008] The present invention has the following aspects. [1] An electrostatic chuck comprising: a dielectric layer; and a first resin layer provided on the dielectric layer, wherein the first resin layer has a holding surface for holding a held member, and wherein a region of the first resin layer in contact with the dielectric layer has a modulus of elasticity at 40°C of 10 MPa or more and 1,000 MPa or less. [2] The electrostatic chuck according to [1], wherein the first resin layer has a mass loss rate of 0.5% or less when heated at 150°C for 24 hours. [3] The electrostatic chuck according to [1] or [2], wherein the first resin layer has a tensile elongation at break of 30% or more and 400% or less. [4] The electrostatic chuck according to any one of [1] to [3], wherein the region of the first resin layer in contact with the held member has a modulus of elasticity at 40°C of 100 MPa or more and 12,000 MPa or less. [5] The electrostatic chuck according to any one of [1] to [4], wherein the peel strength of the first resin layer from the dielectric layer at 140°C is 0.1 N / 25 mm or more and 2.0 N / 25 mm or less. [6] The electrostatic chuck according to any one of [1] to [5], wherein the first resin layer includes a plurality of unit resin layers arranged at a distance from one another. [7] The electrostatic chuck according to any one of [1] to [6], wherein, in a plan view of the dielectric layer, the area of ​​the holding surface is 50% or less of the area of ​​the dielectric layer. [8] The electrostatic chuck according to any one of [1] to [7], wherein a second resin layer is provided between the dielectric layer and the first resin layer. [9] The electrostatic chuck according to [8], wherein the second resin layer covers the surface of the dielectric layer facing the first resin layer and the side surface of the dielectric layer.

[0009] According to the present invention, it is possible to provide an electrostatic chuck that is excellent in durability (heat durability, corrosion resistance, etc.) and contamination resistance (low volatility, particle resistance, etc.).

[0010] 1 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention, taken along a thickness direction of the electrostatic chuck; 2 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention, taken along a thickness direction of the electrostatic chuck; 3 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention, taken along a thickness direction of the electrostatic chuck; and 4 is a cross-sectional view of an electrostatic chuck according to an embodiment of the present invention, taken along a thickness direction of the electrostatic chuck.

[0011] An electrostatic chuck according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of an electrostatic chuck according to one embodiment of the present invention taken along the thickness direction of the electrostatic chuck. Note that, for the sake of clarity, the drawings used in the following description may show characteristic portions enlarged for convenience, and the dimensional ratios of the components may differ from the actual ones. Furthermore, the materials, dimensions, and the like exemplified in the following description are merely examples, and the present invention is not limited thereto. Appropriate modifications may be made within the scope of the present invention.

[0012] 1 , an electrostatic chuck 1 according to this embodiment includes a dielectric layer 10 and a first resin layer 20 provided on the dielectric layer 10. That is, the first resin layer 20 is provided on one main surface (upper surface) 10 a of the dielectric layer 10. The electrostatic chuck 1 has the first resin layer 20 as a holding member that holds a held member, and can be used as an adsorption device that adsorbs and holds the held member.

[0013] The first resin layer 20 has a first adhesive layer 21 and a first base material layer 22 laminated in this order from the side of one main surface 10 a of the dielectric layer 10 .

[0014] The electrostatic chuck 1 may include, for example, an internal electrode 30 inside the dielectric layer 10 as shown in FIG.

[0015] The electrostatic chuck 1 has, for example, a circular shape in a plan view. In a cross-sectional view, as shown in Fig. 1, the first resin layer 20 preferably includes a plurality of unit resin layers 20A arranged at a distance from each other. In the electrostatic chuck 1, for example, the plurality of unit resin layers 20A are arranged concentrically on one main surface 10a of the dielectric layer 10.

[0016] The dielectric layer 10 can be formed from, for example, a heat-resistant resin such as polyimide, polyamide-imide, aromatic polyethylene ketone, or polyphenylene sulfide, or a ceramic such as alumina, silicon carbide (SiC), or yttrium oxide. The dielectric layer 10 is disposed on the side opposite to the side on which the held member is attracted.

[0017] The first resin layer 20 has a holding surface for holding a member to be held. The holding surface of the first resin layer 20 refers to one of the main surfaces (upper surface) 20 a of the first resin layer 20 .

[0018] The elastic modulus of the first resin layer 20 at 40°C in a region in contact with the dielectric layer 10 is 10 MPa or more and 1000 MPa or less, preferably 50 MPa or more and 900 MPa or less, and more preferably 50 MPa or more and 800 MPa or less. When the elastic modulus is equal to or greater than the lower limit, strength and crosslink density increase, improving corrosion resistance against corrosive gases. As a result, durability of the electrostatic chuck 1 improves. When the elastic modulus is equal to or less than the upper limit, flexibility improves, suppressing particle generation due to chipping or peeling during deformation. As a result, contamination resistance of the electrostatic chuck 1 improves. Note that the region of the first resin layer 20 in contact with the dielectric layer 10 specifically refers to the other main surface (lower surface) 20b of the first resin layer 20 and a region in the vicinity thereof. The region in the vicinity of the other main surface 20b of the first resin layer 20 refers to a region 5 μm or less in the thickness direction from the other main surface 20b of the first resin layer 20.

[0019] A dynamic viscoelasticity apparatus can be used to measure the elastic modulus at 40° C. of the region of the first resin layer 20 that is in contact with the dielectric layer 10. For example, the region of the first resin layer 20 that is in contact with the dielectric layer 10 can be cut out and measured under conditions of a temperature rise rate of 5° C. / min and a measurement frequency of 10 Hz, thereby obtaining a value.

[0020] The elastic modulus at 40°C of the region of the first resin layer 20 in contact with the dielectric layer 10 can be controlled by the strength and crosslink density of the resin used in the first resin layer 20, and further by the addition of inorganic materials, etc.

[0021] The elastic modulus of the first resin layer 20 at 40°C in the region in contact with the held member is 100 MPa or more and 12,000 MPa or less, preferably 500 MPa or more and 10,000 MPa or less. When the elastic modulus is equal to or greater than the lower limit, strength and crosslink density increase, improving corrosion resistance against corrosive gases. As a result, durability of the electrostatic chuck 1 improves. When the elastic modulus is equal to or less than the upper limit, flexibility improves, suppressing particle generation due to chipping or peeling during deformation. As a result, contamination resistance of the electrostatic chuck 1 improves. Note that the region of the first resin layer 20 in contact with the held member specifically refers to one main surface 20a of the first resin layer 20 and a region in the vicinity thereof. The region in the vicinity of one main surface 20a of the first resin layer 20 refers to a region 10 μm or less in the thickness direction from one main surface 20a of the first resin layer 20.

[0022] The modulus of elasticity at 40°C of the region of the first resin layer 20 in contact with the held member can be measured in the same manner as the modulus of elasticity at 40°C of the region of the first resin layer 20 in contact with the dielectric layer 10 described above.

[0023] The elastic modulus at 40°C of the region of the first resin layer 20 that comes into contact with the supported member can be controlled by the strength and crosslink density of the resin used in the first resin layer 20, and further by the addition of inorganic materials.

[0024] The first resin layer 20 preferably has a mass loss rate of 0.5% or less, more preferably 0.4% or less, and even more preferably 0.3% or less when heated at 150° C. for 24 hours. When the mass loss rate is equal to or less than the upper limit, contamination of the held member by volatile matter can be suppressed in the plasma treatment step, thereby improving contamination resistance.

[0025] A thermogravimetric differential thermal analyzer (TG-DTA) can be used to measure the mass loss rate of the first resin layer 20 when heated at 150°C for 24 hours. For example, the mass loss rate can be measured by heating the first resin layer 20 to 150°C at a heating rate of 5°C / min in a nitrogen atmosphere, and then maintaining the temperature at 150°C for 24 hours.

[0026] The mass reduction rate of the first resin layer 20 can be controlled by the crosslink density, impurity content, low-molecular-weight content, and addition of inorganic materials in the resin constituting the first resin layer 20 .

[0027] The first resin layer 20 preferably has a tensile elongation at break of 30% or more and 400% or less, more preferably 50% or more and 300% or less, and even more preferably 50% or more and 200% or less. When the tensile elongation at break is equal to or greater than the lower limit, flexibility is improved, and generation of particles due to chipping or peeling during deformation can be suppressed. As a result, the contamination resistance of the electrostatic chuck 1 is improved. When the tensile elongation at break is equal to or less than the upper limit, strength is increased, and corrosion resistance against corrosive gases is improved. As a result, durability of the electrostatic chuck 1 is improved.

[0028] A universal testing machine can be used to measure the tensile elongation at break of the first resin layer 20. For example, the first resin layer 20 is cut into a strip (1 mm wide x 4 mm long) and both ends of the strip are held together by gripping parts of the universal testing machine, the upper and lower gap of which is set to 2 mm, and the strip is pulled at a tensile speed of 10 mm / min, and the distance traveled by the gripping parts until the first resin layer 20 breaks is measured, thereby obtaining a value.

[0029] The tensile elongation at break of the first resin layer 20 can be controlled by the molecular weight and crosslink density of the resin used in the first resin layer 20, and further by adding an inorganic material.

[0030] In a plan view of the dielectric layer 10, the area of ​​the holding surface of the first resin layer 20 (one of the main surfaces 20 a of the first resin layer 20) relative to the area of ​​the dielectric layer 10 (the area of ​​one of the main surfaces (upper surface) 10 a of the dielectric layer 10) is preferably 50% or less, more preferably 30% or less, and even more preferably 20% or less. When the area ratio of the holding surface of the first resin layer 20 relative to the area of ​​the dielectric layer 10 is within the above range, the area in contact between the holding surface of the first resin layer 20 and the held member is reduced, thereby reducing the number of particles adhering to the surface of the held member that contacts the holding surface of the first resin layer 20. As a result, the contamination resistance of the electrostatic chuck 1 is improved.

[0031] The first resin layer 20 may be composed of unit resin layers 20A. In the first resin layer 20, all of the unit resin layers 20A may have the same configuration or different configurations. The configuration here refers to the configuration of the first adhesive layer 21 and the configuration of the first base material layer 22, which will be described later. If all of the unit resin layers 20A have the same configuration, the plasma treatment can be performed uniformly on the upper surface of the held member, making it suitable for use in an electrostatic chuck device. If the unit resin layers 20A have different configurations, the plasma treatment on the upper surface of the held member can be intentionally made non-uniform, making it suitable for use in an electrostatic chuck device.

[0032] Examples of adhesives that can be used for the first adhesive layer 21 include thermoplastic polyimide adhesives, thermosetting polyimide adhesives, polyamide adhesives, epoxy adhesives, polyester adhesives, silicone adhesives, olefin adhesives, and anchor coating agents. From the viewpoints of corrosion resistance and contamination resistance, thermoplastic polyimide adhesives, thermosetting polyimide adhesives, polyamide adhesives, and epoxy adhesives can be preferably used.

[0033] The thickness of the first adhesive layer 21 is not particularly limited, but is preferably 1 μm to 25 μm, more preferably 3 μm to 15 μm, and even more preferably 3 μm to 10 μm. When the thickness of the first adhesive layer 21 is equal to or greater than the lower limit, the adhesive strength to the dielectric layer 10 is increased, and thermal stress during the plasma treatment process can be alleviated, thereby improving durability. When the thickness of the first adhesive layer 21 is equal to or less than the upper limit, the adhesive strength to the dielectric layer 10 is increased, and the area of ​​the first adhesive layer 21 in contact with corrosive gas is reduced, thereby improving corrosion resistance. As a result, the durability of the electrostatic chuck 1 is improved.

[0034] Examples of resins that can be used to form the first base layer 22 include polyimide, polyphenylene sulfide, aromatic polyethylene ketone, polyimide resin, polyethylene terephthalate, polypropylene, and polytetrafluoroethylene.

[0035] The thickness of the first base layer 22 is not particularly limited, but is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 40 μm or less, and even more preferably 10 μm or more and 30 μm or less. When the thickness of the first base layer 22 is equal to or greater than the lower limit, the corrosion resistance of the first resin layer 20 in the holding surface direction against the corrosive gas is increased. As a result, the durability of the electrostatic chuck 1 is improved. When the thickness of the first base layer 22 is equal to or less than the upper limit, the holding force for the held member is increased, and the risk of contaminants getting mixed in between the holding surface of the first resin layer 20 and the held member is reduced. As a result, the contamination resistance of the electrostatic chuck 1 is improved.

[0036] The electrostatic chuck 1 of this embodiment is highly durable and can be used repeatedly in semiconductor manufacturing processes. However, if the holding surface deteriorates or becomes contaminated due to corrosive gases or particles, the first resin layer 20 (holding surface) can be replaced, allowing the electrostatic chuck 1 to be used for an even longer period of time (repairability). That is, the first resin layer 20 may be easily peeled and removed from the dielectric layer 10 as long as the function of the electrostatic chuck 1 is not impaired. From the viewpoint of repairability, it is preferable that no residue of the first resin layer 20 remains on the surface of the dielectric layer 10. Specifically, the first resin layer 20 preferably has a peel strength of the first adhesive layer 21 to the dielectric layer 10 at 25°C of 0.1 N / 25 mm or more and 3.0 N / 25 mm or less, and more preferably 0.2 N / 25 mm or more and 2.0 N / 25 mm or less. It is more preferable that the dielectric layer 10 and the adhesive layer 21 are separated from each other without leaving any residue when measuring this peel strength. This allows the first resin layer 20 to be easily removed from the electrostatic chuck 1. Therefore, by replacing the first resin layer 20 (first base material layer 22 and first adhesive layer 21) that has deteriorated due to corrosive gases, the electrostatic chuck 1 can be easily maintained in good condition, and as a result, the durability of the electrostatic chuck 1 can be maintained.

[0037] Furthermore, the peel strength of the first resin layer 20 to the dielectric layer 10 at 140°C (for example, when the first adhesive layer 21 is present, the peel strength of the first adhesive layer 21 to the dielectric layer 10 at 140°C) is preferably 0.1 N / 25 mm or more and 2.0 N / 25 mm or less, and more preferably 0.1 N / 25 mm or more and 1.0 N / 25 mm or less. When measuring this peel strength, it is more preferable that the dielectric layer 10 and the adhesive layer 21 are separated from each other without leaving any residue. This allows the first resin layer 20 to be easily removed from the electrostatic chuck 1. Therefore, by replacing the first resin layer 20 (the first base material layer 22 and the first adhesive layer 21) that has deteriorated due to a corrosive gas, the electrostatic chuck 1 can be easily maintained in good condition, resulting in improved durability of the electrostatic chuck 1.

[0038] The method for measuring the peel strength of the first adhesive layer 21 to the dielectric layer 10 at 25°C and 140°C is not particularly limited, but can be measured in accordance with JIS-Z-0237. Specifically, the first resin layer 20 is cut into 25 mm wide strips from the holding surface side of the electrostatic chuck 1, and the electrostatic chuck 1 is then placed in a universal tensile tester (RTH-2410, manufactured by A&D Co., Ltd.), and the longitudinal ends of the strip-shaped first resin layer 20 are gripped with a test measurement jig provided on the universal tensile tester. The strip-shaped first resin layer 20 is then peeled from the dielectric layer 10 at test temperatures of 25°C and 140°C, a peel angle of 90°, and a test speed of 200 mm / min, to obtain the peel strength. This test is repeated three times, and the average peel strength obtained is used as the peel strength. The peel strength of the first adhesive layer 21 from the dielectric layer 10 decreases steadily from 25°C to 140°C. This is thought to be due to a decrease in the cohesive force of the first adhesive layer 21. When the electrostatic chuck 1 is used in a semiconductor manufacturing device, the ambient temperature within the device and the temperature of the holding surface (one of the main surfaces 20a of the first resin layer 20) are adjusted to suit the semiconductor manufacturing process. When the operating temperature range of the electrostatic chuck 1 is 140°C or less, the adhesive peel strength of the first adhesive layer 21 from the dielectric layer 10 at 140°C indicates the durability of the first adhesive layer 21 at 140°C. A peel strength of 0.1 N / 25 mm or greater can prevent damage to the first resin layer 20 during the semiconductor manufacturing process. Furthermore, during repair, the ability to peel the first adhesive layer 21 from the dielectric layer 10 at room temperature (25°C) prevents damage to the electrostatic chuck 1 and maintains the quality of the electrostatic chuck 1 after repair, which is preferable. For example, when the peel strength of the first adhesive layer 21 to the dielectric layer 10 at 25°C is 3.0 N / 25 mm or less, the possibility of residues being generated on each side is reduced, the quality of the electrostatic chuck 1 after repair is maintained, and even if residues are generated on each side, the possibility of damage to the electrostatic chuck 1 can be reduced. Note that if it is difficult to peel the first adhesive layer 21 from the dielectric layer 10 at room temperature (25°C), the peel strength of the first adhesive layer 21 may be reduced at a high temperature (140°C) and repair may be performed. Therefore, the peel strength of the first adhesive layer 21 to the dielectric layer 10 is evaluated at 25°C and 140°C.

[0039] The internal electrode 30 is not particularly limited and is composed of, for example, a layered conductor. The conductor of the internal electrode 30 is not particularly limited, but one or more metals such as copper, aluminum, gold, silver, platinum, chromium, nickel, tungsten, and stainless steel are preferably used. The conductor of the internal electrode 30 may be an alloy containing at least one of these metals, or may be a mixture with a ceramic material. Examples of ceramic materials include alumina, silicon carbide, and yttrium oxide.

[0040] In the electrostatic chuck 1 of this embodiment, the first resin layer 20 that holds the held member has excellent durability and contamination resistance.

[0041] Other Embodiments The present invention is not limited to the above-described embodiments.

[0042] For example, modified examples such as those shown in Figures 2 and 3 may be employed. In the modified examples, the same components as those in the above embodiment are denoted by the same reference numerals, and their description will be omitted, with only the differences being described.

[0043] First Modification An electrostatic chuck 100 according to a first modification shown in FIG. 2 includes a second resin layer 40 between the dielectric layer 10 and the first resin layer 20 .

[0044] The second resin layer 40 has a second adhesive layer 41 and a second base material layer 42 laminated in this order from the side of one main surface 10 a of the dielectric layer 10 .

[0045] The second adhesive layer 41 has the same configuration as the first adhesive layer 21. The second base material layer 42 has the same configuration as the first base material layer 22.

[0046] According to the electrostatic chuck 100 of the first modified example, the second resin layer 40 is provided between the dielectric layer 10 and the first resin layer 20, thereby further improving the corrosion resistance and particle resistance of the first resin layer 20.

[0047] "Second Modification" In an electrostatic chuck 200 of a second modification shown in FIG. 3, a second resin layer 40 covers the surface of the dielectric layer 10 facing the first resin layer (one of the main surfaces 10a of the dielectric layer 10) and the side surface 10b of the dielectric layer 10.

[0048] According to the first modified electrostatic chuck 100, the second resin layer 40 covers the surface of the dielectric layer 10 facing the first resin layer and the side surface 10b of the dielectric layer 10, and therefore the second resin layer 40 can improve the corrosion resistance and particle resistance of the dielectric layer 10.

[0049] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[0050] [Fabrication of Electrostatic Chuck] An example of a method for fabricating an electrostatic chuck according to this embodiment will be described. However, the present invention is not limited to this fabrication method. A metal such as copper is vapor-deposited on the surface (upper surface in the thickness direction) of a base to form a thin metal film. Then, etching is performed to pattern the thin metal film into a predetermined shape to form an electrode. The electrode may be one or more. In addition to a holding electrode that holds a held member, the electrode may also include a high-frequency electrode that controls high-frequency plasma or a thermal resistor that heats the held member.

[0051] Next, an adhesive layer is attached to the upper surface of the electrode so as to cover the end of the electrode, and a dielectric layer is attached via the adhesive layer to form a laminate. The dielectric layer may be formed by thermal spraying, by applying and solidifying a resin or inorganic paste, or by combining multiple layers.

[0052] Next, an adhesive layer was attached to the laminate, and a resin film was attached via the adhesive layer to form a second resin layer. Alternatively, a resin may be applied to the top surface or the top and side surfaces of the laminate to form the second resin layer. The resin is not particularly limited, but can be formed by applying the resin and then drying or heating it to solidify it.

[0053] Next, an adhesive sheet having a first base material layer attached to the first adhesive layer was attached to the second resin layer. Here, the adhesive sheet may be punched. The first resin layer is not particularly limited, but may be formed by applying a resin and then drying or heating it to solidify it.

[0054] Example 1 An electrostatic chuck of Example 1 was fabricated to have the configuration shown in Table 1. Specifically, copper was vapor-deposited on the surface of a base (diameter 300 mm, thickness 5 mm) to form a thin copper film. The copper film had a thickness of 10 μm. Etching was then performed to pattern the thin copper film into a predetermined shape to form an electrode. An adhesive sheet 1 was then attached to the upper surface of the electrode so as to cover the edge of the electrode, and a substrate 4 was attached via the adhesive sheet 1 to form a laminate. The adhesive sheet 1 was then attached to the upper surface and side of the laminate, and the substrate 1 was punched and attached via the adhesive sheet 1 to form a second resin layer. Next, an adhesive tape with the adhesive sheet 1 attached to the substrate 1 was attached to the second resin layer. The adhesive tape used was punched to uniformly arrange 150 disks with a diameter of 4 mm on the second resin layer. After the adhesive sheet, substrate 1, substrate 4, laminate and second resin layer were attached to each other, they were heated at 180° C. for 1 hour to harden and bond them together.

[0055] Example 2 An electrostatic chuck of Example 2 was fabricated in the same manner as Example 1 so as to have the configuration shown in Table 1. In the electrostatic chuck of Example 2, the second resin layer was formed only on the upper surface of the laminate.

[0056] [Example 3] An electrostatic chuck of Example 3 was fabricated in the same manner as in Example 1 so as to have the configuration shown in Table 1. In the electrostatic chuck of Example 3, the second resin layer was not formed, and the first resin layer was formed on the upper surface of the dielectric layer.

[0057] Example 12 An electrostatic chuck of Example 12 was fabricated in the same manner as Example 1 so as to have the configuration shown in Table 1. The electrostatic chuck of Example 12 did not have a first base material layer. As a result, the upper surface of the first adhesive layer served as the holding surface.

[0058] [Examples 4 to 11, 13 to 27, Comparative Example 1] Electrostatic chucks of the respective examples were fabricated in the same manner as in Example 1 so as to have the configurations shown in Tables 1 to 5.

[0059] Comparative Example 2 An electrostatic chuck of Comparative Example 2 was fabricated to have the configuration shown in Table 4. Specifically, copper was vapor-deposited on the surface of a base (diameter 300 mm, thickness 5 mm) to form a thin copper film. The copper film had a thickness of 10 μm. Etching was then performed to pattern the thin copper film into a predetermined shape to form an electrode. An adhesive sheet 1 was then attached to the upper surface of the electrode so as to cover the end of the electrode, and an alumina plate (diameter 300 mm, thickness 0.125 mm) was then attached via the adhesive sheet 1 to fabricate an electrostatic chuck. After the adhesive sheet, electrode, base, and alumina plate were attached, they were heated at 180° C. for 1 hour to harden and bond.

[0060] [Evaluation] "Area ratio of the support surface of the first resin layer" When the dielectric layer was viewed in plan, the area of ​​the support surface of the first resin layer relative to the area of ​​the dielectric layer (the area of ​​one of the main surfaces of the dielectric layer) was measured. Specifically, using known image analysis software, the area was calculated as the average value of values ​​obtained by the following formula. The results are shown in Tables 1 to 4. Area ratio of the support surface of the first resin layer = Area of ​​the support surface of the first resin layer / Area of ​​one of the main surfaces of the dielectric layer (area of ​​the upper surface of the electrostatic chuck) × 100

[0061] "Tensile elongation at break of first resin layer" The tensile elongation at break of the first resin layer was measured. Specifically, the first resin layer was cut into a strip (1 mm wide x 4 mm long), and both long ends of the strip were held together by gripping parts of a universal testing machine (RTF-1310 manufactured by A&D Co., Ltd.) with a vertical gap of 2 mm, and the strip was pulled at a tensile speed of 10 mm / min. The distance traveled by the gripping parts until the first resin layer broke was measured, and a measurement value was obtained. The results are shown in Tables 1 to 4.

[0062] "Mass loss rate when the first resin layer is heated at 150°C for 24 hours" The mass loss rate when the first resin layer is heated at 150°C for 24 hours was measured. Specifically, a thermogravimetric differential thermal analyzer (TG-DTA) (Shimadzu Corporation, TG / DTA simultaneous measurement device DTG-60) was used to measure under the following conditions. In a nitrogen atmosphere, the temperature was increased to 150°C at a rate of 5°C / min, and then the temperature was maintained at 150°C for 24 hours. The mass loss rate was calculated from the obtained value to obtain a measured value. The results are shown in Tables 1 to 4.

[0063] "Elastic modulus at 40°C of region of first resin layer in contact with dielectric layer" The elastic modulus at 40°C of the region of the first resin layer in contact with the dielectric layer was measured. Specifically, a dynamic viscoelasticity apparatus (HR-20 manufactured by TA Instruments) was used to measure under the following conditions. The region of the first resin layer in contact with the dielectric layer was cut out along the first resin layer to a thickness of 5 μm, and then laminated to a thickness of 200 μm ± 20 μm. After leaving the sample at 40°C for 30 minutes, measurements were performed at a measurement frequency of 10 Hz, and the elastic modulus at 40°C was calculated. The results are shown in Tables 1 to 4.

[0064] "Elastic modulus at 40°C of the region of the first resin layer in contact with the held member" The elastic modulus at 40°C of the region of the first resin layer in contact with the held member was measured in the same way as the elastic modulus at 40°C of the region of the first resin layer in contact with the dielectric layer. The results are shown in Tables 1 to 4.

[0065] "Corrosion Resistance" The corrosion resistance of the first resin layer was evaluated. Specifically, the first resin layer was cut into a disk shape with a diameter of 4 mm. Then, it was exposed to hydrogen fluoride gas for 24 hours under the conditions below, and the weight change rate before and after the test was calculated to obtain a value. The corrosion resistance was evaluated as follows: if the weight change before and after the test was less than 0.01%, it was evaluated as "◎", if the weight change before and after the test was 0.01% or more but less than 0.05%, it was evaluated as "○", if the weight change before and after the test was 0.05% or more but less than 0.15%, it was evaluated as "△", and if the weight change was 0.15% or more, it was evaluated as "×". The results are shown in Tables 1 to 4.

[0066] "Holding Force" The holding force of the holding surface was evaluated. Specifically, the upper surface of the holding member was maintained at 50°C, and a silicon dummy wafer was used as the held member. The dummy wafer was adsorbed onto the holding surface under vacuum (10 Pa or less). A voltage of +2.5 kV was applied to the electrode, and the dummy wafer was held for 30 seconds. Helium gas was then flowed into the space surrounded by the dielectric layer, the first resin layer, and the dummy wafer while the voltage was still applied. The amount of helium gas leakage at a gas pressure of 100 Torr was measured to evaluate the holding force. The holding force was evaluated as follows: when the helium gas leakage rate was less than 0.5 sccm, it was rated as "◎"; when it was 0.5 sccm or more but less than 1.0 sccm, it was rated as "○"; when it was 1.0 sccm or more but less than 3.0 sccm, it was rated as "△"; and when it was 3.0 sccm or more, it was rated as "X". The results are shown in Tables 1 to 4.

[0067] "Particle Resistance" Particle resistance was evaluated. Specifically, after adsorbing a dummy wafer in the same manner as in the evaluation of "retention force," the holding surface was heated from 50°C to 150°C at a temperature increase rate of 5°C / min, and once it reached 150°C, the holding surface was cooled to 50°C at a temperature decrease rate of 5°C / min. Thereafter, the application of voltage was stopped, the dummy wafer was removed from the holding surface, and the number and size of particles adhering to the surface of the dummy wafer that had been adsorbed to the holding surface were measured using a wafer surface inspection device (manufactured by Topcon Corporation, product name WM-7S). The number of particles with a diameter of 0.5 μm or more but less than 1.0 μm and the number of particles with a diameter of 1.0 μm or more were counted. The particle resistance was evaluated as follows: when the total number of particles was less than 1000, "◎", when the number of particles was 1000 or more but less than 5000, "◯", when the number of particles was 5000 or more but less than 10000, "Δ", and when the number of particles was 10000 or more, "×". The results are shown in Tables 1 to 4.

[0068] "Thermal Durability" The thermal durability was evaluated. Specifically, cracking or peeling of the first resin layer after thermal cycling was evaluated. That is, the electrostatic chuck was placed in a thermostatic chamber (TCC-151W manufactured by Espec Corporation) set at 0°C. The chamber was then heated to 120°C at a heating rate of 50°C / hour and then immediately cooled to 0°C at a cooling rate of 50°C / hour. This process was repeated 200 times. After 200 cycles, the electrostatic chuck was removed from the thermostatic chamber, and the appearance of each evaluation sample was observed and evaluated. The thermal durability was evaluated as follows: "Excellent" when no cracking or peeling occurred in the first resin layer; "Good" when only peeling occurred in the first resin layer; "Fair" when only cracking occurred in the first resin layer; and "Poor" when both peeling and cracking occurred in the first resin layer. The results are shown in Tables 1 to 4.

[0069] "Evaluation of Repairability" Repairability was evaluated. Specifically, the peel strength of the first adhesive layer against the dielectric layer was measured at 23°C and 140°C in accordance with JIS-Z-0237. The first resin layer was cut into 25 mm-wide strips from the holding surface side of the electrostatic chuck 1, and the electrostatic chuck was then placed in a universal tensile tester (RTH-2410, manufactured by A&D Co., Ltd.). The longitudinal ends of the strip-shaped first resin layer were gripped with a test measurement jig attached to the universal tensile tester. The strip-shaped first resin layer was then peeled from the dielectric layer at test temperatures of 23°C and 140°C, a peel angle of 90°, and a test speed of 200 mm / min. The peel strength was measured, and the presence or absence of residue on the dielectric layer was observed. This test was repeated three times, and the average peel strength was used to evaluate repairability. Repairability was evaluated based on the presence or absence of adhesive residue. The results are shown in Table 5.

[0070]

[0071]

[0072]

[0073]

[0074]

[0075] In Tables 1 to 4, substrate 1 is Kapton 50EN manufactured by DuPont-Toray Co., Ltd., substrate 2 is Kapton 50H manufactured by DuPont-Toray Co., Ltd., substrate 3 is Upilex 25S manufactured by Ube Industries, Ltd., substrate 4 is Kapton 100EN manufactured by DuPont-Toray Co., Ltd., substrate 5 is Kapton 150EN manufactured by DuPont-Toray Co., Ltd., substrate 6 is Kapton 200EN manufactured by DuPont-Toray Co., Ltd., substrate 7 is Torelina #16-3030 manufactured by Toray Industries, Inc., substrate 8 is Lumirror #12-S10 manufactured by Toray Industries, Inc., substrate 9 is Torayfan #30-2500H manufactured by Toray Industries, Inc., and substrate 10 is a tetrafluoroethylene-hexafluoropropylene copolymer film manufactured by Daikin Corporation. Adhesive 1 is obtained by adding 5 parts by mass of JER604 manufactured by Mitsubishi Chemical Corporation to 100 parts by mass of PIAD100H manufactured by Arakawa Chemical Industries, Ltd. and mixing them. Adhesive 2 is obtained by adding 5 parts by mass of JER604 manufactured by Mitsubishi Chemical Corporation and 7 parts by mass of AA-04 manufactured by Sumitomo Chemical Co., Ltd. to 100 parts by mass of PIAD100H manufactured by Arakawa Chemical Industries, Ltd. and mixing them. Adhesive 3 is obtained by adding 5 parts by mass of JER604 manufactured by Mitsubishi Chemical Corporation and 10 parts by mass of AA-04 manufactured by Sumitomo Chemical Co., Ltd. to 100 parts by mass of PIAD100H manufactured by Arakawa Chemical Industries, Ltd. and mixing them. Adhesive 4 is styrene-ethylene butylene-styrene block copolymer H1043 manufactured by Asahi Kasei Chemicals Corporation. Adhesive 5 was obtained by mixing 100 parts by mass of Coponyl 8976L manufactured by Mitsubishi Chemical Corporation with 3 parts by mass of hardener SC-55LT manufactured by Aica Kogyo Co., Ltd. The above mixing ratio is the ratio in the adhesive composition after drying and solidifying.

[0076] The results shown in Tables 1 to 4 show that the electrostatic chucks of Examples 1 to 23 are excellent in corrosion resistance and particle resistance.

[0077] The results shown in Table 5 reveal that the electrostatic chucks of Examples 1, 8, and 24 to 27 have excellent repairability.

[0078] 1, 100, 200 Electrostatic chuck 10 Dielectric layer 20 First resin layer 21 First adhesive layer 22 First base material layer 30 Internal electrode 40 Second resin layer 41 Second adhesive layer 42 Second base material layer

Claims

1. An electrostatic chuck comprising a dielectric layer and a first resin layer provided on the dielectric layer, the first resin layer having a holding surface for holding a workpiece, and the first resin layer having a modulus of elasticity at 40°C in a region in contact with the dielectric layer of 10 MPa or more and 1000 MPa or less.

2. The electrostatic chuck according to claim 1, wherein the first resin layer has a mass reduction rate of 0.5% or less when heated at 150°C for 24 hours.

3. The electrostatic chuck according to claim 1, wherein the first resin layer has an elongation at break in tension of 30% or more and 400% or less.

4. The electrostatic chuck according to claim 1, wherein the first resin layer has a modulus of elasticity at 40°C in a region in contact with the workpiece of 100 MPa or more and 12000 MPa or less.

5. The electrostatic chuck according to claim 1, wherein the peel strength of the first resin layer with respect to the dielectric layer under 140°C conditions is 0.1 N / 25 mm or more and 2.0 N / 25 mm or less.

6. The electrostatic chuck according to claim 1, wherein the first resin layer includes a plurality of unit resin layers arranged spaced apart from each other.

7. The electrostatic chuck according to claim 1, wherein in a plan view of the dielectric layer, the area of the holding surface is 50% or less of the area of the dielectric layer.

8. The electrostatic chuck according to claim 1, further comprising a second resin layer between the dielectric layer and the first resin layer.

9. The electrostatic chuck according to claim 8, wherein the second resin layer covers a surface of the dielectric layer facing the first resin layer and a side surface of the dielectric layer.

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