A New Purged UV Spectroscopic Ellipsometer to characterize 157nm nanolithographic materials

Spectroscopic ellipsometry has long been recognized as the technique of choice to characterize thin films and multilayers. It is now intensively used in microelectronics and especially for the microlithographic applications. Instrumentation for the next generation of UV lithography at 157nm requires special optical setup since oxygen and water are extremely absorbing below 190nm. The ellipsometer discussed in this paper works into a purged glove box to reduce the oxygen and water contamination in the part per million ranges. The optical setup has been especially studied for microlithographic applications. It includes for example a premonochromator in the polariser arm to avoid resist photobleaching. Technical details of the system and some first measurement results on substrates and thin films are reported hereafter.