Secondary ion yields depending on the primary oxygen ion energy in Cameca IMS-4f instrument

The secondary ion yields of six element in silicon were measured as a function of the primary oxygen ion energy in a Cameca IMS-4f SIMS instrument. The ion yields of elements with a high ionization potential decrease steeply with primary ion energy owing to the decreasing surface oxygen concentration. The decrease of the ion yield depends on the ionization potential. This relation and the known relative sensitivity factors enable a semi-quantitative analysis of impurities in silicon to be carried out without standard samples. A similar study combined with oxygen flooding shows that the yields are now very high and independent of the primary ion energy. Profile distortions due to segregation effects, however, can occur. A comparison of the ion yields obtained with and without energy offset under low and high oxygen surface coverage shows that the shape of the arsenic secondary ion energy distribution is drastically changed leading to pronounced differences in ion yields. (author)