Using a Cs+ primary beam on a Cameca IMS SIMS instrument and ion implanted standards in Cu, it has been found that H, C, O, Cl in Cu films can be measured using negative secondary ions and a low to medium mass resolution (MIDeltaM < 3000), however, S and P analysis require a higher mass resolution to resolve the mass interferences present in the barrier layer (TiSiN and TaN). Analysis of nitrogen required monitoring of the (Cs2N)(+) secondary ions. Sodium and potassium secondary ions need to be measured as positive secondary ions. The analysis energy should be chosen based on the thickness of the Cu films, where thinner films (20 nm) require a very low profiling energy and this low profiling energy can be achieved by monitoring of the (Cs2M)(+) molecular ions (M = H, C, etc.). (C) 2004 Elsevier B.V. All rights reserved.