Depth Profiling of Na in SiOx Films by Combination of Chemical Etching and Secondary Ion Mass Spectrometry

A simple procedure to obtain accurate secondary ion mass spectrometry (SIMS) depth profiles of Na in SiOx films has been studied. SiOx on Si samples implanted with Na were etched off with HF solution and the surfaces were analyzed with SIMS after being coated with Ag. The Na intensity at the Ag/SiOx interface was plotted against the etched-off depth and the depth profile of Na was obtained. On comparing these results with those by Lindhard, Scharff and Schiott (LSS) simulation, it was proved that this procedure is useful for the depth profiling of Na in SiOx films. This technique was also applied to the analysis of Na in various types of SiOx films, which were fabricated with different processes and have different densities and compositions. It was found that this technique is quite effective for analyzing the Na distribution in the samples which cannot be analyzed accurately by the self-charge compensation method due to the structural properties of the films.