Evaluation of the contamination removal capability and multilayer degradation in various cleaning methods

In this test, we evaluated the carbon contamination removal capabilities of various kinds of cleaning methods. And we also evaluated the degradation of multilayer (with capping layer) caused by the cleaning process. In the contamination removal test, the contamination was formed by a synchrotron irradiation. And in the degradation test, we evaluated Ru-capping layer and Si-capping layer. In the contamination removal test, the reflectivity recovery was confirmed in all cleaning conditions that were evaluated. However, there were differences among the reflectivity recoveries. In particular, plasma cleaning showed high removal capability. In VUV/O3 cleaning, the oxygen concentration influenced the contamination removal capability. In Si-capping layer, none of the cleaning conditions exhibited any significant reflectance change. On the other hand, in Ru-capping layer, a decrease in reflectance was noticed in VUV/O3 cleaning with an oxygen concentration of 500ppm. In a comparison between Ru-capping layer and Si-capping layer, no significant difference was noticed in SPM cleaning, VUV/O3 with oxygen concentration 45ppm, and in plasma with N2/H2 gas condition.