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As a participant of the French Extreme UltraViolet (EUV) program PREUVE, our laboratory has been involved for one year in the development of Mo/Si blanks free of defects using an Ion Beam Sputtering deposition technique (IBS). Among the different tasks to end at an EUV stepper, the achievement of the blank and its characterization in terms of defect counting is probably one of the most challenging. This is the reason why a characterization tool based on the well known scattering method is under progress in our laboratory. In addition to defect counting, the possibility of cleaning a sample (substrate, blanks,.) with a powerful laser source is allowed on the same facility. This set up is fully computerized. Its first performances are illustrated with several examples on our blanks and silicon substrates. Our system is designed to optimize the laser cleaning parameters (wavelength, incidence, polarization,.) and to decrease the detection limit size. Today, our facility currently enables the detection of the defect as small as 200 nm in size. Our strategy is to reach the defect size as low as possible and at least until 50 nm, which is the size of interest for the EUV lithography. The major developments under consideration in order to lessen the detection limit size are described in details in this paper. Moreover, the roughness of the EUV blanks may be evaluated with our device. This surface parameter has to be optimized, at least for two reasons : to reduce the optical losses and to decrease the number of defects. The mean to quench the roughness signal in order to detect the smallest defect size and the possibility to evaluate the component roughness are combined on the same facility. The major trumps of our experiment are the visualization of the defects in live, the measurement of the defect sizes and the quick evaluation of the laser cleaning efficiency versus various experimental conditions. The cleaning part of the set up is built up to use various powerful laser sources and to shoot, with the laser, only the locations where the defects remain. Finally, this facility allows to evaluate and to optimize our defect free blank process.
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