Abstract: Systems and methods for mitigating and reducing contamination of one or more components of overlay inspection systems are disclosed. Specifically, embodiments of the present disclosure may utilize a counterflow of purge gas through a counterflow nozzle to reduce the presence of contaminants within one or more portions of an inspection system. The system may include a source chamber, one or more vacuum chambers, an intermediate focus housing having an aperture, an illumination source configured to generate and direct illumination through the aperture in an illumination direction, and a counterflow nozzle configured to direct a counterflow of purge gas into the source chamber in a direction opposite the illumination direction.

Abstract: A light source includes a rotatable drum to be coated with xenon ice and illuminated by a laser beam to produce a plasma. The drum may also be translatable. The light source further includes a confocal chromatic sensor to measure distances from the confocal chromatic sensor to the rotatable drum. The confocal chromatic sensor may include a sensor head to focus light onto the rotatable drum and to detect reflected light from the rotatable drum. The sensor head and the rotatable drum may be disposed within a vacuum chamber.

Abstract: Systems and methods for mitigating and reducing contamination of one or more components of overlay inspection systems are disclosed. Specifically, embodiments of the present disclosure may utilize a counterflow of purge gas through a counterflow nozzle to reduce the presence of contaminants within one or more portions of an inspection system. The system may include a source chamber, one or more vacuum chambers, an intermediate focus housing having an aperture, an illumination source configured to generate and direct illumination through the aperture in an illumination direction, and a counterflow nozzle configured to direct a counterflow of purge gas into the source chamber in a direction opposite the illumination direction.