Investigation of the thermal stability of Mg/Co periodic multilayers for EUV applications

We present the results of the characterization of Mg/Co periodic multilayers and their thermal stability for the EUV range. The annealing study is performed up to a temperature of 400\degree C. Images obtained by scanning transmission electron microscopy and electron energy loss spectroscopy clearly show the good quality of the multilayer structure. The measurements of the EUV reflectivity around 25 nm (~49 eV) indicate that the reflectivity decreases when the annealing temperature increases above 300\degreeC. X-ray emission spectroscopy is performed to determine the chemical state of the Mg atoms within the Mg/Co multilayer. Nuclear magnetic resonance used to determine the chemical state of the Co atoms and scanning electron microscopy images of cross sections of the Mg/Co multilayers reveal changes in the morphology of the stack from an annealing temperature of 305\degreee;C. This explains the observed reflectivity loss.Comment: Published in Applied Physics A: Materials Science \& Processing Published at http://www.springerlink.com.chimie.gate.inist.fr/content/6v396j6m56771r61/ 21 page

Effets d'un chauffage thermique sur les performances de miroirs multicouches Mo/Si, Mo/C et Ni/C pour le rayonnement X mou

Les effets d'un chauffage thermique continu sur les performances en terme de réflectivité de miroirs multicouches Mo/Si, Mo/C, Ni/C sont étudiés. Les mesures de réflectivité autour de 100eV sont réalisées en utilisant le rayonnement synchrotron de Super-ACO au LURE. Des variations de réflectivité en fonction de la température sont enregistrées. On observe que la période du miroir Mo/Si décroît, celui du miroir Mo/C reste constante et celle du miroir Ni/C croît quand la température augmente. Ces comportements sont discutés dans le cadre de la science des matériaux.The effects of continuous thermal annealing on the performances in terms of reflectivity of Mo/Si, Mo/C, Ni/C multilayer mirrors are studied. The measurements of reflectivity around 100eV are performed by using the synchrotron radiation supplied by Super-ACO at the LURE. Variations of reflectivity versus the temperature are recorded. We observe that the period of the Mo/Si mirror decreases, the one of the Mo/C mirror remains constant and the one of the Ni/C increases as the annealing temperature increases. These behaviours are discuted in the framework of material science