Real-time X-ray reflectometry during thin-film processing

An apparatus and a characterization technique have been developed at the ESRF beamline BM5 to investigate in-situ the evolution of the morphology of a film using grazing incidence X-ray reflectometry. The instrument is capable of measuring in-situ and in real time the X-ray intensity specularly and diffusely scattered from a rough thin film during various surfacing processes. The variation of the specular intensity as a function of the processing time, recorded simultaneously with each X-ray scattering diagram, is analyzed to infer the film growth rate, the film density and the variation of roughness conformity during surface processing. The potential of the method is demonstrated for two particular cases: thin film deposition by magnetron sputtering and subsequent film etching by low energy ion bombardment. The paper describes some recent achievements and present examples of on-line diagnostics for which real time in-situ X-rays reflectometry proves to be a unique probe. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)