Journal of Vacuum Science & Technology B Microelectronics Processing and Phenomena · 1987 · 19 citations · 0 references
Natural SciencesChemistryMaterials ScienceSpectroscopySurface ChemistrySurface ScienceAtomic IonizationCluster ChemistryMass SpectrometryMetal OxidesSurface PhysicsSurface SpectroscopyExcitationIonizationResonance Ionization SpectroscopyRovibronic StructureSecondary Ion Mass SpectrometrySputteringSurface SputteringTime-of-flight Secondary Ion Mass Spectrometry
The yield of neutral and ionized Mo, Mo2, and Mo3 sputtered from a Mo target by 4-keV Ar+ has been measured in the surface analysis by resonance ionization of sputtered atoms (SARISA) machine. Ionization spectroscopy combined with time-of-flight (TOF) secondary ion mass spectrometry (SIMS) allowed us to obtain for the first time absolute sputtering yields and ionization fractions of sputtered atoms and metal clusters. Unlike sputtered atomic species, Mo clusters have been found to be sputtered with large ion fractions. The sputtering yield of Mo clusters is very sensitive to oxygen on the surface, i.e., even small amounts of oxygen on the surface identified by Mo+ and MoO+ peaks in the SIMS spectrum, reduce the cluster yield substantially. A broad structureless absorption band was observed for sputtered Mo2 molecules indicating substantial rovibronic excitation as predicted by theoretical models.