Analysis of alkali elements in insulators using a CAMECA IMS-6f

Secondary ion mass spectroscopic analysis of insulators is difficult becaus e charging of the sample affects the trajectories of primary and secondary ions. Analysis of alkali elements in insulators is additionally complicated by the mobility of the species of interest under the influence of an elect ric field. Magnetic sector analyzers also present difficulties in providing charge neutralization because of the high electric field required to injec t ions into the analyzer. Coating of the sample with a conductive film or g rid has often been needed to provide a meaningful analysis. However, coatin g the sample adds a contaminant source that complicates alkali analysis, es pecially at the concentrations of interest to the semiconductor industry. I n this article we provide, for a magnetic sector instrument, a method that requires no coating or sample preparation prior to analysis. If the electro n penetration depth is matched to the thickness of the oxide layer, results show that SiO2 layers from 0.3 to 1.36 mu m thick can be easily and repeat ably analyzed for alkali elements using this approach. (C) 2000 American Va cuum Society. [S0734-2101(00)03401-1].