High-pressure container, substrate processing apparatus, and method for manufacturing high-pressure container

A high-pressure container comprising:

• a container body including a flat rectangular parallelepiped block of a metal which is formed with a flat cavity that serves as a substrate processing space in which a processing using a high-pressure fluid is performed on a substrate, the flat cavity being formed by machining the flat rectangular parallelepiped block from one of faces of the flat rectangular parallelepiped block other than a widest face towards another face opposing thereto;
• and
• a cover configured to open/close the substrate processing space,
• wherein at least one of inner wall surfaces of the flat cavity is coated with a plating layer of a noble metal, and an electroless nickel plating layer is interposed between the inner wall surfaces of the flat cavity and the plating layer of the noble metal, and
• a thickness of the plating layer of the noble metal is about 0.2 μm.