Patent ID: 8562266

Claim:
A fastener assembly for use in a plasma processing chamber which avoids parasitic plasma formation when used to attach parts inside the plasma chamber, the fastener assembly comprising: a bolt having a tubular body with an axially extending center through hole, a threaded outer surface, and a non-cylindrical tool engaging socket at the top of the through hole, the socket configured to engage a tool used to rotate the bolt during insertion of the bolt in a threaded hole; a pin having a shaft extending a length greater than a length of the through hole, the pin being movable from a lower position at which an upper portion of the through hole is not filled to an upper position at which a top face of the pin is flush with a top face of the bolt; and a spring biasing the pin in the upper position, such that the pin is retractable from the upper position to the lower position when a tool is inserted in the tool engaging socket at the top of the through hole; wherein the pin includes a rim between the spring and an axial end of the bolt, the rim engaging the axial end of the bolt when the pin is in the upper position.