Surface analysis of insulating materials by Secondary Ion Mass Spectrometry (SIMS)

For a non-conducting solid sample (TiO₂ powder) the conditions for compensation of the charge build-up at the surface caused by the ion impact in SIMS are experimentally investigated. The compensation is achieved by an additional auxiliary electron beam of low energy. The resolution and the intensities of the secondary ions were measured as a function of the ratio of the current densities of the electron and the ion beams. The compensation for negative secondary ions, and especially for those with higher masses, is more critical than for positive ones. The intensities are influenced by the different values of the mean emission energies and the form of the energy distributions. Examples of mass spectra by SIMS for some insulators are given.