Static SIMS inter-laboratory study

An inter-laboratory study involving 18 respondees, with 21 static SIMS inst ruments, has been conducted with a wide variety of spectrometer types. Thes e include quadrupole, magnetic setter and three time-of-flight mass analyse r designs, representing an essential cross-section of the main laboratories using static SIMS. This study involved the static SIMS analysis of three reference samples pro vided by the NPL: poly(tetrafluoroethene), poly(ethene terephthalate) and a thin layer of Irganox 1010 on silver. Respondees recorded data for both po sitive and negative secondary ions in the static mode and, if time permitte d, as a function of the ion fluence. The results of this study show that static SIMS instruments can have excell ent repeatabilities of better than 18. A relative instrument spectral respo nse (RISR) is calculated for each instrument with an average reproducibilit y of 14%, for the different reference materials and for both ion polarities . The RISR facilitates the transferability and equivalence of data from lab oratory to laboratory, This means that spectra have a reproducibility, afte r correction using the RISR, of x/ divided by 1.14 compared with a value fo ur times worse with no correction, problems that lead to variability are th e sample handling and sample contamination, the energy band pass of the spe ctrometer and the mass transmission function of the analyser. However, domi nating all of these, at the present time, seems to be the local procedures for set-up and use of each instrument. It is believed that, if these can be improved, static SIMS can be a reliable measurement method. Crown Copyrigh t (C) 2000. Reproduced with the permission of the Controller of HMSO.