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August, 2002 EEEL Researchers Develop New Excimer Laser Special Test |
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To meet the semiconductor industry’s demands for accurate excimer laser measurements, Holger Laabs, Darryl Keenan, Shao Yang, and Marla Dowell have recently developed a new service to accurately characterize the nonlinearity of an excimer laser energy detector. This service, which complements other NIST excimer laser power and energy calibration services, provides a quantitative measurement of a detector’s response over a large energy range. Most detectors are typically used over an energy range that is too large to be supported by calibration at a single energy level. Testing of typical detectors has shown nonlinearities as large as 8 %. In addition to inherent nonlinearities in the detector, electronic effects such as range discontinuity and background can contribute to apparent detector nonlinearity. Detector nonlinearity measurements are now being offered as Special Tests at the excimer laser wavelength of 193 nm, pending full documentation. Additional excimer laser wavelengths will be added to this service in the near future. The nonlinearity measurements are performed using a beamsplitter-based calibration system in which a spatially uniform beam from an ArF excimer laser is generated using a special beam homogenizer. Measurement traceability for these calibrations stems from an electrically calibrated, primary standard calorimeter developed by EEEL scientists Chris Cromer and Marla Dowell.
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