Status of EUV reflectometry at PTB

With several pre-production EUV tools already in the field, the development of EUV Lithography has gained momentum and the first production tools are scheduled for delivery in 20131. Consequently, the demand for EUV radiometry has grown as well with respect to volume and variety of the measurement requirements. Building on almost two decades of experience, PTB offers a wide range of actinic EUV measurements, like reflectance and transmittance, to characterize optical elements and sensitivity measurements to characterize detection devices. Based on these core competences, new applied measurements can be offered. Diffusely scattered light can be used to assess surface roughness (PSD) in the otherwise difficult to measure spatial frequency region of 1 mu m to 10 mu m. PTB performs EUV metrology at two dedicated complementary beamlines covering the wavelength range from 0.65 nm to 30 nm with particularly well-collimated radiation and the range from 5 nm to 50 nm with higher radiant power, variable degree of polarization and adjustable spot size on the sample. Both beamlines are optimized to achieve temporally stable normalized radiant power and excellent wavelength reproducibility at high spectral purity with out-of-band radiation in the range of 10(-3) relative, as a prerequisite for low measurement uncertainties and long-term reproducibility. We present an updated overview of our capabilities with a focus on the long-term stability of our instrumentation and methods.