Patent ID: 11913874
Assignee: KLA CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An optical metrology tool, comprising:
a modulatable pumping source configured to generate illumination beam;
a plasma cell, the plasma cell including a bulb for containing a volume of gas;
a set of optical elements configured to shape the illumination beam and focus the illumination beam from the modulatable pumping source into the volume of gas in order to maintain a plasma within the volume of gas;
a set of illumination optics configured to direct the illumination beam from the plasma cell to the surface of a sample;
a set of collection optics;
a detector configured to detect at least a portion of illumination emanating from a surface of a sample, wherein the set of collection optics is configured to direct illumination from the surface of the sample to the detector;
a pump control system communicatively coupled to the modulatable pumping source, wherein the pump control system includes one or more processors configured to execute program instructions maintained on a carrier medium configured to cause the pump control system to modulate a drive current of the modulatable pumping source at a selected modulation frequency in order to produce time-varying characteristics within the plasma contained within the plasma cell.