Quantitative fundamental SIMS studies using 18O implant standards

The use of dilute 'minor-isotope' 18O implant reference standards for quantification of surface oxygen levels during steady-state SIMS depth profiling is demonstrated. Some results of two types of quantitative fundamental SIMS studies with oxygen (16O) primary ion bombardment and/or oxygen flooding (O2 gas with natural isotopic abundance) are presented: (1) Determination of elemental useful ion yields, UY(X±), and sample sputter yields, Y, as a function of the oxygen fraction cO measured in the total flux emitted from the sputtered surface. Examples include new results for positive secondary ion emission of several elements (X = B, C, O, Al, Si, Cu, Ga, Ge, Cs) from variably oxidized SiC or Ge surfaces. (2) The dependence of exponential decay lengths λ(Au±) in sputter depth profiles of gold overlayers on silicon on the amount of oxygen present at the sputtered silicon surface. The latter study elucidates the (element-specific) effects of oxygen-induced surface segregation artifacts for sputter depth profiling through metal overlayers into silicon substrates.