Abstract: A system that includes a phase locked loop and an activation circuit; wherein the phase locked loop includes an oscillator, a frequency divider, a phase detector, a control circuit, and a memory circuit. The activation circuit is adapted to activate the memory circuit and the oscillator; to deactivate the frequency divider, the phase detector and the control circuit during deactivation periods and to activate the frequency divider, the phase detector and the control circuit during activation periods. The timing relationship between a deactivation period and an activation period is responsive to an output signal jitter limitation and to a power consumption limitation.

Abstract: Systems and methods for monitoring and controlling the operation of extreme ultraviolet (EUV) sources used in semiconductor fabrication are disclosed. A method comprises providing a semiconductor fabrication apparatus having a light source that emits in-band and out-of-band radiation, taking a first out-of-band radiation measurement, taking a second out-of-band radiation measurement, and controlling the in-band radiation of the light source, at least in part, based upon a comparison of the first and second out-of-band measurements. An apparatus comprises a detector operable to detect out-of-band EUV radiation emitted by an EUV plasma source, a spectrometer coupled to the electromagnetic detector and operable to measure at least one out-of-band radiation parameter based upon the detected out-of-band EUV radiation, and a controller coupled to the spectrometer and operable to monitor and control the operation of the EUV plasma source based upon the out-of-band measurements.