Development of a compact angle-resolved secondary ion mass spectrometer for Ar⁺ sputtering

A compact angle-resolved secondary ion mass spectrometer with a special geometrical configuration, composing of a differentially pumped micro-beam ion gun, a tiltable sample stage and a time-of-flight (TOF) mass spectrometer, was newly developed. This system enables the measurement of angular distribution (AD) of secondary ions, which are ejected by oblique Ar⁺ sputtering, by a simple tilt operation of the sample stage for ejection angles ranging from 0° to 60° with keeping the ion incidence angle constant 62°±2° from the normal to the surface. Using this system, AD of secondary ions from an HfN film by 3 keV Ar⁺-ion bombardment was measured at room temperature. Since the yield of HfN⁺ dimer ions was almost independent of Hf⁺ and N⁺ monomer ions, it was concluded that the HfN⁺ dimer ions were generated via the "as such" direct emission process.