There is a substrate processing system including a vacuum chamber in which a predetermined processing is performed on a substrate. In the substrate processing system, an opening in communication with the vacuum chamber is opened/closed by a valve body of a gate valve installed between the vacuum chamber and a conveyance chamber, so that the substrate held by a conveyance arm is carried into or carried out from the vacuum chamber.
For example, in a conveyance device that conveys a plurality of substrates arranged vertically into the vacuum at once, a gate valve is installed between the vacuum chamber and the conveyance. In the gate valve, a plurality of valve bodies is arranged vertically in multi-tiers (see, e.g., Japanese Patent Laid-Open Publication No. 2014-49532). Each valve body is supported by a shaft. The shaft is elevated by a driving unit so that the valve bodies are integrally moved so as to open/close openings.
The vacuum chamber is controlled under vacuum so that the pressure therein is lower than the pressure in the conveyance chamber. Therefore, due to the difference in pressure between the vacuum and the conveyance chamber, the gate valve is applied with a pressure of approximately several hundred kg to a thousand kg from the openings depending on the number of the valve bodies. Accordingly, as an example, a mechanism is used, in which an abutment plate is installed near the valve bodies to which the pressure is applied at the time of opening/closing such that the shafts supporting the valve bodies are guided by the abutment plate to suppress a deformation amount of the shafts, thereby increasing a mechanical strength.