Precise electronic structure analysis of inorganic thin films by highly optimized argon-gas-cluster ion-beam sputtering

Ar-ion sputtering, a common method for removing surface organic contamination, severely denatures oxide-based materials owing to collision cascades and preferential sputtering. To mitigate these challenges, an Ar gas-cluster ion beam (Ar GCIB) sputtering process for selective organic-material etching has been developed in this study. Electronic structures of HfO_x thin films grown on Si (HfO_x/Si) have been analyzed by X-ray photoelectron spectroscopy (XPS) and utilized to optimize the Ar GCIB sputtering conditions. Evidently, the optimal conditions (acceleration voltage: 3.75 kV, raster size: 2 × 2 or 5 × 5 mm², and operation time: 2–5 min) reduce surface carbon contamination to below 1 % while preserving the intrinsic XPS electronic structure. Other analyses, including reflective electron energy loss spectroscopy, transmission electron microscopy, and current–electrical field curves, similarly confirm the absence of surface degradation in the sputtered HfO_x/Si sample. Following this validation, further analyses are performed to confirm the applicability and analytical effectiveness of Ar GCIB sputtering for other samples.