Conduit system of a radiation source and methods thereof

An apparatus comprising:

• a chamber configured to hold a fluorine-containing gas;
• a conduit configured to circulate the fluorine-containing gas to or from the chamber during generation of radiation, at least a portion of the conduit being defined by a conduit wall;
• and
• a unidirectional check valve disposed in the conduit, the unidirectional check valve comprising
• a sphere comprising nickel disposed within the conduit and subjected to exposure to the fluorine-containing gas, the sphere being movable between a first position in which the unidirectional check valve is closed and a second position in which the unidirectional check valve is open, and
• a neodymium permanent magnet disposed in proximity to the conduit wall outside of the chamber and an interior of the conduit so as not to be subject to exposure to the fluorine-containing gas, the neodymium permanent magnet being arranged to exert a biasing force on the sphere urging the sphere into the first position.

A radiation source configured to generate radiation, the radiation source comprising:

• a chamber configured to confine a corrosive gas and a contaminant produced during generation of the radiation;
• a window configured to isolate the corrosive gas from an environment external to the chamber and to allow the radiation to travel between the chamber and the environment;
• and
• a conduit system comprising
• a refill path configured to allow a replacement of the corrosive gas, and
• a conduit configured to circulate the corrosive gas to or from the chamber during the generation of the radiation;
• and
• a unidirectional valve disposed to intersect the conduit and configured to prevent flow of the contaminant toward the window, the unidirectional check valve comprising
• a check valve element comprising a ferromagnetic material having a first magnetic field strength and a first corrosion resistance disposed within the conduit and subjected to exposure to the corrosive gas, the check valve element being movable between a first position in which the unidirectional check valve is closed and a second position in which the unidirectional check valve is open, and
• a permanent magnet comprising a magnetized material having a second field strength greater than the first field strength and a second corrosion resistance less than the first corrosion resistance disposed in proximity to the conduit wall, outside of the chamber and outside of the conduit so as not to be subjected to exposure to the corrosive gas, the permanent magnet being arranged to exert a biasing force on the check valve element urging the check valve element into the first position,
• wherein the conduit system is configured to direct a flow of one of a refill gas, the corrosive gas, or the refill gas and the corrosive gas at least during a refill operation to prevent the contaminant from contacting the window, whereby the conduit system increases usable lifetime of at least the window.