Patent attributes
A substrate processing apparatus of which through holes in a mounting stage can be properly sealed. A substrate processing apparatus comprises a plate-like mounting stage having a plurality of first through holes, a base member including a plurality of second through holes that have female thread portions, a plurality of pin-shaped members being passed through and fitted into the first and second through holes and including flange portions, a plurality of sealing surfaces, and a plurality of sealing members disposed such as to enclose openings of the first through holes. One ends of the pin-shaped members project out from the sealing surfaces, and the other ends have male thread portions capable of engaging with female thread portions of the base member. When the base member moves away from the mounting stage, an end of each of the female thread portions comes into abutment with an end of each of the male thread portions.