WIT Press

EUV Detection System With Calibrated Responsivity


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J. Mikolajczyk & Z. Bielecki


We describe a measuring system of EUV radiation energy using special calibration responsivity. This system is specified by responsivity of 0.043 A/W at the wavelength range of 13.5±0.5 nm (FWHM=7.2%). A determination of the calibration responsivity for a laser-plasma source with Xe/He gas puff target is also discussed. This parameter makes it possible to reference measurement results to the standard wavelengths band of 13.5±0.13 nm (FWHM=2%). The value of the calibration responsivity depends on the spectra of measured radiation and features of the system elements. In this paper, the analysis and investigation results of the source and the measuring system are demonstrated. Keywords: EUV radiation, optical sensors, energy meter. 1 Introduction Accurate measurements of energy radiation are very important in nanolithography. The resists or masks can be damaged due to the measurements errors. Nowadays, energy meters of EUV radiation are also used for testing of lithography tools. The investigations are connected with characterization of EUV radiation sources, features of optical elements, etc. The responsivity and measurement accuracy are the main features of the measuring devices. The parameters are referenced to a standard wavelength range of 13.5±0.13 nm. The range corresponds with the FWHM=2%. The developed commercial meters are usually built from multilayer mirrors and semiconductor detectors [1]. The mirrors simplify construction of the instruments. Using photodiodes makes it possible to achieve a high efficiency and plain measurements procedures. The pulse energy of radiation is determined by the measured charge generated in a photodiode, the value of the detector


EUV radiation, optical sensors, energy meter.