Plasma processing apparatus and manufacturing method of wafer stage for plasma processing apparatus

A manufacturing method of a wafer stage of a plasma processing apparatus having a wafer stage, the plasma processing apparatus being disposed inside a processing chamber inside a vacuum container and a wafer to be processed being configured to be placed on an upper surface of the wafer stage, the plasma processing apparatus being configured to process the wafer by forming plasma inside the processing chamber, wherein

• the wafer stage includes
• a metallic base material disposed inside the wafer stage and having a cylindrical shape or a circular plate shape,
• a dielectric film disposed on an upper surface of the base material, made of a dielectric material and constituting a placement surface on which the wafer is configured to be placed,
• a film-shaped heater disposed inside the dielectric film,
• a refrigerant flow path multiply disposed in a concentric shape or in a spiral shape about a center of the base material inside the base material and allowing a refrigerant to flow therethrough, and
• at least one arc-shaped space multiply disposed about the center inside the base material between the refrigerant flow path and the heater and having an inside reduced to a predetermined degree of vacuum and sealed,
• a bridge portion, which is a region of a portion of the base material between the multiply disposed arc-shaped spaces, is projected and overlapped on a region of an intermediate portion of the base material that partitions two of the adjacent refrigerant flow paths when viewed from above,
• wherein the arc-shaped space is formed by welding, in a space having a degree of vacuum approximate to the predetermined degree of vacuum, a recess portion formed in advance in at least one of an upper member and a lower member which are welded to each other and constitute the base material, and the other member, and
• wherein the manufacturing method of the wafer stage of the plasma processing apparatus further comprises a communication path communicating the two arc-shaped spaces disposed adjacent to each other with the bridge portion interposed therebetween.