Vessel for extreme ultraviolet radiation source

A method of operating an EUV light generation apparatus, wherein the EUV light generation apparatus includes a vessel having a gas inlet, an interface port connected to a scanner, a gate valve disposed at the interface port and an exhaust port, the method comprising:

• generating EUV light while supplying a gas from the gas inlet and exhausting the gas from the exhaust port;
• stopping the EUV light generation;
• after stopping the EUV light generation, monitoring a pressure turbulence adjacent to a scanner gate valve;
• and
• after determining that the pressure turbulence exceeds a threshold, increasing a flow rate of the exhaust gas exhausted from the exhaust port.

An apparatus for generating extreme ultraviolet (EUV) radiation, comprising:

• a chamber;
• an EUV vessel disposed in the chamber, wherein the EUV vessel comprising:
• a gas inlet configured to provide a cleaning gas into the EUV vessel;
• an interface port to be connected to a scanner;
• a gate valve disposed at the interface port and an exhaust port;
• and
• a controller configured to control the gate valve to suppress airflow from the gate valve toward the collector mirror.