Investigation of in-situ cleaning for tin and its oxidized contaminants on ruthenium
An experimental study of in-situ cleaning of tin and its oxide contaminants on the surfaces of the ru-thenium layers of multilayer mirrors.Granules and thin films of tin with oxide contaminants were deposited on ruthenium surfaces by a physical vapor deposition(PVD).The hydrogen plasma for cleaning at different pow-ers was systematically diagnosed by a Langmuir probe and a retarding field ion energy analyzer(RFEA).Comparisons of the cleaning rates of the tin granules and thin films with oxide contaminants revealed that the cleaning rate on top of the granular contaminants was the highest,while the cleaning rate of contaminants on the tin thin film is the lowest.The XPS analyses of the Sn 3d peaks demonstrated a breakage of tin-oxygen bonds and a process of chemical reduction after 1 W cleaning.The SEM cross-section images showed an in-crease of the base film thickness after 1 W cleaning,indicating a phenomenon of redeposition during the clean-ing processes.The TRIM simulations illustrated that the hydrogen injection depth was larger at the high power(10 W),whereas was lower at the low power(1 W)than the ruthenium film thickness.The roughness of the ruthenium film substrate remained stable during the 10 h and 1 W irradiation.During chemical reduction and etching,hydrogen ions and hydrogen radicals play roles of breaking chemical bonds and reactants,respec-tively.According to the above results,it is found that the low-power(1 W)hydrogen plasma can achieve a non-destructive in-situ cleaning of tin and its oxide contaminants.
Tin and its oxide contaminantsHydrogen plasmaRutheniumIn-situ cleaning
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