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EP-4738431-A1 - ELECTROSTATIC CHUCK

EP4738431A1EP 4738431 A1EP4738431 A1EP 4738431A1EP-4738431-A1

Abstract

An electrostatic chuck (1) includes: a substrate (2) for attracting an object to be attracted; a base (3) that supports the substrate (2); and an adhesive layer (4) that bonds the substrate (2) to the base (3). The adhesive layer (4) has a first adhesive layer (4a) positioned on the central side of the substrate (2), and a second adhesive layer (4b) positioned closer to an end of the substrate (2) than the first adhesive layer (4a). A plasma-protective layer (5) is provided closer to the end of the substrate (2) than the second adhesive layer (4b), and the plasma-protective layer (5) is bonded to the second adhesive layer (4b). The second adhesive layer (4b) has a Young's modulus at 100°C of 1 MPa or more, and a Young's modulus at 25°C of 1000 MPa or less.

Inventors

  • MORIUCHI, HIDEKI

Assignees

  • Tomoegawa Corporation

Dates

Publication Date
20260506
Application Date
20240621

Claims (9)

  1. An electrostatic chuck, comprising: a substrate for attracting an object to be attracted; a base for supporting the substrate; and an adhesive layer for bonding the substrate to the base, wherein the adhesive layer has a first adhesive layer positioned on a central side of the substrate, and a second adhesive layer positioned closer to an end of the substrate than the first adhesive layer; wherein a plasma-protective layer is provided closer to the end of the substrate than the second adhesive layer, and the plasma-protective layer is bonded to the second adhesive layer; and wherein the second adhesive layer has a Young's modulus at 100°C of 1 MPa or more, and a Young's modulus at 25°C of 1000 MPa or less.
  2. The electrostatic chuck according to claim 1, wherein the second adhesive layer has a Young's modulus at 100°C of 10 MPa or more, and a Young's modulus at 25°C of 500 MPa or less.
  3. The electrostatic chuck according to claim 1, wherein the first adhesive layer has a Young's modulus at 25°C in the range of 2000 MPa to 5000 MPa.
  4. The electrostatic chuck according to claim 1, wherein the plasma-protective layer is disposed on a side closer to the center of the substrate than an end of the substrate.
  5. The electrostatic chuck according to claim 4, wherein the plasma-protective layer is disposed at a distance in the range of 50 µm to 1000 µm from the end of the substrate toward the center of the substrate.
  6. The electrostatic chuck according to claim 1, wherein the second adhesive layer has a shape recessed toward the central side of the substrate.
  7. The electrostatic chuck according to claim 1, wherein the first adhesive layer contains a thermally conductive filler.
  8. The electrostatic chuck according to any one of claims 1 to 7, wherein the plasma-protective layer contains an inorganic material.
  9. The electrostatic chuck according to claim 8, wherein the inorganic material is made of at least one of yttrium, aluminum, zirconium, calcium, and magnesium.

Description

TECHNICAL FIELD The present invention relates to an electrostatic chuck. BACKGROUND ART Conventionally, etching apparatuses that perform plasma dry etching of wafers have been used as semiconductor manufacturing equipment. In such etching apparatuses, an electrostatic chuck is used to secure a planar material using static electricity. In such an electrostatic chuck, a substrate for attracting the planar material and a base that supports the substrate are bonded by an adhesive layer. To mitigate damage to the adhesive layer from plasma, a plasma-protective layer is bonded to the outer surface of the adhesive layer. International Patent Application Publication No. WO2016/132909 discloses an electrostatic chuck in which the plasma-protective layer is composed of an organic material such as fluorine or an acrylic resin. SUMMARY OF THE INVENTION If there is a large difference in the coefficient of linear thermal expansion between the substrate for attracting a planar material and the base supporting the substrate, the substrate and the base will expand or contract respectively due to changes in the ambient temperature, and the resulting deformation of the adhesive layer can cause damage to the electrostatic chuck. An object of the present invention is to provide an electrostatic chuck that can suppress such damage. An electrostatic chuck of the present disclosure comprises: a substrate for attracting an object to be attracted;a base that supports the substrate; andan adhesive layer that bonds the substrate to the base, wherein the adhesive layer has a first adhesive layer positioned on a central side of the substrate, and a second adhesive layer positioned closer to an end of the substrate than the first adhesive layer,wherein a plasma-protective layer is provided closer to the end of the substrate than the second adhesive layer, and the plasma-protective layer is bonded to the second adhesive layer, andwherein the second adhesive layer has a Young's modulus at 100°C of 1 MPa or more, and a Young's modulus at 25°C of 1000 MPa or less. In the electrostatic chuck of the present disclosure, the second adhesive layer may have a Young's modulus at 100°C of 10 MPa or more, and a Young's modulus at 25°C of 500 MPa or less. In the electrostatic chuck of the present disclosure, the first adhesive layer may have a Young's modulus at 25°C in the range of 2000 MPa to 5000 MPa. In the electrostatic chuck of the present disclosure, the plasma-protective layer may be disposed on a side closer to the center of the substrate than an end of the substrate. In the electrostatic chuck of the present disclosure, the plasma-protective layer may be disposed at a distance in the range of 50 µm to 1000 µm from the end of the substrate toward the center of the substrate. In the electrostatic chuck of the present disclosure, the second adhesive layer may have a shape recessed toward the central side of the substrate. In the electrostatic chuck of the present disclosure, the first adhesive layer may contain a thermally conductive filler. In the electrostatic chuck of the present disclosure, the plasma-protective layer may contain an inorganic material. In the electrostatic chuck of the present disclosure, the inorganic material may be made of at least one of yttrium, aluminum, zirconium, calcium, and magnesium. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a schematic configuration of an electrostatic chuck according to an embodiment of the present disclosure.FIG. 2 is a cross-sectional view showing a schematic configuration of another electrostatic chuck according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. FIGS. 1 and 2 are cross-sectional views showing the schematic configurations of electrostatic chucks according to embodiments of the present disclosure. [Electrostatic chuck 1] As shown in FIGS. 1 and 2, an electrostatic chuck 1 according to the present embodiment comprises a substrate 2 for attracting an object to be attracted, a base 3 that supports the substrate 2, and an adhesive layer 4 that bonds the substrate 2 to the base 3. The adhesive layer 4 has a first adhesive layer 4a positioned on the central side of the substrate 2, and a second adhesive layer 4b positioned closer to an end of the substrate 2 than the first adhesive layer 4a. Furthermore, the electrostatic chuck 1 comprises a plasma-protective layer 5 provided closer to the end of the substrate 2 than the second adhesive layer 4b, and the plasma-protective layer 5 is bonded to the second adhesive layer 4b. (Substrate 2) The substrate 2 is for attracting and holding an object to be attracted (not shown). The shape of the substrate 2 is not limited, and may have a disk shape or a rectangular shape in accordance with the shape of the object to be attracted. The dimensions of the substrate 2 can also be set as