Detection in the ppm range and high-resolution depth profiling with the new SNMS instrument INA-X

The design and the specification of the newly developed INA-X instrument for the electron-gas version of a secondary neutral mass spectrometer (SNMS) are described. A modified plasma chamber inside a UHV vessel in combination with optimized r.f. coupling enable a high plasma density at low power input. The ionization efficiency and the current density for sample sputtering are significantly improved compared to those of previous SNMS instruments. A novel detection optics allows us to define an energy window of 1–2 eV. The secondary neutral particle flux is collected under an oblique take-off angle against the surface normal, improving the quantifiability of the obtained SNMS spectra. The variable sputtering rate can be adjusted from some nm per min up to 1–2 μm per min, depending on the operator’s need, either to obtain high depth resolution or short analysis time. Examples for depth profiling of conducting and insulating films and coatings on the nano- and micrometer scales are presented.