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US-20260128263-A1 - WAFER PLACEMENT TABLE

US20260128263A1US 20260128263 A1US20260128263 A1US 20260128263A1US-20260128263-A1

Abstract

A wafer placement table includes a ceramic plate that has at least a wafer placement part at an upper surface thereof, a cooling plate that is joined to a lower surface of the ceramic plate and that has a refrigerant flow path, gas common paths that are provided above the refrigerant flow path, gas introduction paths that extend from a lower surface of the cooling plate to a corresponding one of the gas common paths, and a plurality of gas distribution paths, that are provided for the gas common paths. The gas distribution path that is disposed at an outermost periphery of the ceramic plate is provided at a position that does not overlap the refrigerant flow path in plan view.

Inventors

  • Masaki Ishikawa
  • Tatsuya Kuno
  • Tomoya INA

Assignees

  • NGK INSULATORS, LTD.

Dates

Publication Date
20260507
Application Date
20260105

Claims (6)

  1. 1 . A wafer placement table comprising: a ceramic plate that has at least a wafer placement part at an upper surface thereof; a cooling plate that is joined to a lower surface of the ceramic plate and that has a refrigerant flow path; a gas common path that is provided, of an inside of the wafer placement table, at a location above the refrigerant flow path; a gas introduction path that extends from a lower surface of the cooling plate to the gas common path; and a gas distribution path that extends from the gas common path to the upper surface of the ceramic plate, a plurality of the gas distribution paths being provided for the gas common path, wherein the gas distribution paths have an outermost peripheral gas distribution path that is disposed at an outermost periphery of the ceramic plate, the outermost peripheral gas distribution path is provided at a position that does not overlap the refrigerant flow path in plan view, wherein a plurality of the gas common paths are concentrically provided, wherein the outermost peripheral gas distribution path is connected to, of the plurality of the gas common paths, the gas common path that is positioned at an outermost periphery, wherein the gas distribution paths are connected to the gas common path through a gas branch part, and wherein, among the gas branch parts, a gas branch part connected to the outermost peripheral gas distribution path extends outward in a plane.
  2. 2 . The wafer placement table according to claim 1 , wherein at least a portion of the gas distribution path that is connected to the gas branch part has a width that is larger than a width of the gas common path.
  3. 3 . The wafer placement table according to claim 1 , wherein the cooling plate is made of a composite material of a metal and a ceramic.
  4. 4 . The wafer placement table according to claim 1 , wherein the wafer placement part that is formed circularly and a ring-shaped focus ring placement part that surrounds the wafer placement part are provided at the upper surface of the ceramic plate, and wherein the outermost peripheral gas distribution path is a path that extends from the gas common path to the focus ring placement part.
  5. 5 . The wafer placement table according to claim 1 , wherein the wafer placement part that is formed circularly is provided at the upper surface of the ceramic plate, and wherein the outermost peripheral gas distribution path is a path that extends from the gas common path to the wafer placement part.
  6. 6 . A wafer placement table comprising: a ceramic plate that has at least a wafer placement part at an upper surface thereof; a cooling plate that is joined to a lower surface of the ceramic plate and that has a refrigerant flow path; a gas common path that is provided, of an inside of the wafer placement table, at a location above the refrigerant flow path; a gas introduction path that extends from a lower surface of the cooling plate to the gas common path; and a gas distribution path that extends from the gas common path to the upper surface of the ceramic plate, a plurality of the gas distribution paths being provided for the gas common path, wherein the gas distribution paths have an outermost peripheral gas distribution path that is disposed at an outermost periphery of the ceramic plate, the outermost peripheral gas distribution path is provided at a position that does not overlap the refrigerant flow path in plan view, wherein a plurality of the gas common paths are concentrically provided, wherein the outermost peripheral gas distribution path is connected to, of the plurality of the gas common paths, the gas common path that is positioned at an outermost periphery, wherein the wafer placement part that is formed circularly and a ring-shaped focus ring placement part that surrounds the wafer placement part are provided at the upper surface of the ceramic plate, wherein the outermost peripheral gas distribution path is a path that extends from the gas common path to the focus ring placement part, and wherein the gas common paths are located at positions lower than a focus ring support surface of the focus ring placement part.

Description

CROSS REFERENCE TO RELATED APPLICATION This application is a continuation of U.S. Application Serial No. 18/302,027, filed April 18, 2023, which in turn is a continuation of International Application No. PCT/JP2022/038367, filed October 14, 2022, which designated the United States, the entireties of which are incorporated herein by reference. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer placement table. 2. Description of the Related Art To date, a wafer placement table including a ceramic plate that has a wafer placement part at its upper surface, a cooling plate that is joined to a lower surface of the ceramic plate, and a refrigerant flow path that is provided in the cooling plate has been known. For example, in a wafer placement table in Patent Literature 1, gas introduced from a lower surface of a cooling plate is supplied from a gas common path that is provided above a refrigerant flow path and that is C-shaped in cross section to an upper surface of a ceramic plate by passing through a gas distribution path through a plurality of gas branch parts, the gas branch parts extending in a radially outward direction from the gas common path, the gas distribution path extending through the ceramic plate in an up-down direction. CITATION LIST PATENT LITERATURE PTL 1: Japanese Unexamined Patent Application Publication No. 2021-141116 SUMMARY OF THE INVENTION However, although when using a wafer placement table, a large stress may be produced in the gas distribution path that is positioned at an outermost periphery of the wafer placement table, Patent Literature 1 does not consider this point, as a result of which cracks may be produced in the wafer placement table. In particular, when a wafer is processed by using high-power plasma, such cracks tend to be produced. The present invention has been made to overcome such a problem, and a primary object of the present invention is to prevent cracks from being produced in a wafer placement table. [1] A wafer placement table of the present invention comprises: a ceramic plate that has at least a wafer placement part at an upper surface thereof; a cooling plate that is joined to a lower surface of the ceramic plate and that has a refrigerant flow path; a gas common path that is provided, of an inside of the wafer placement table, at a location above the refrigerant flow path; a gas introduction path that extends from a lower surface of the cooling plate to the gas common path; and a gas distribution path that extends from the gas common path to the upper surface of the ceramic plate, a plurality of the gas distribution paths being provided for the gas common path, wherein the gas distribution paths have an outermost peripheral gas distribution path that is disposed at an outermost periphery of the ceramic plate, the outermost peripheral gas distribution path is provided at a position that does not overlap the refrigerant flow path in plan view. In the wafer placement table, of the gas distribution paths, the outermost peripheral gas distribution path that is disposed at the outermost periphery of the ceramic plate is provided at a position that does not overlap the refrigerant flow path in plan view. When using the wafer placement table, a large stress tends to be produced at the outermost periphery of the wafer placement table. When the outermost peripheral gas distribution path overlaps the refrigerant flow path in plan view, since a portion directly above the refrigerant flow path is thin and tends to be deformed, cracks tend to be produced near the outermost peripheral gas distribution path. However, here, since the outermost peripheral gas distribution path is provided at a position that does not overlap the refrigerant flow path in the plan view, it is possible to decrease stress near the outermost peripheral gas distribution path and to prevent cracks from being produced. Note that, in the present description, the present invention is described by using terms, such as up, down, left, right, front, and rear. However, up, down, left, right, front, and rear merely refer to relative positional relationships. Therefore, when the orientation of the wafer placement table is changed, up and down may become left and right, or left and right may become up and down. Accordingly, such cases are also included in the technical scope of the present invention. [2] In the wafer placement table described above (the wafer placement table in [1] above), the gas distribution paths may be connected to the gas common path through a gas branch part. If this is the case, for example, when, in plan view, the gas branch part from the gas common path crosses the refrigerant flow path and reaches a position that does not overlap the refrigerant flow path, it is possible to relatively easily provide the gas distribution paths at positions that do not overlap the refrigerant flow path. [3] In the wafer placement table described above (the wafe