Radiofrequency GDOES: a powerful technique for depth profiling analysis of thin films

Abstract

AbstractPreviously, glow discharge optical emission spectroscopy (GDOES), both d.c. and r.f. has been used for depth profiling analysis of thick films several tens of microns thick, utilizing its high sputtering rates of >1 µm min−1. Through selected examples, it is demonstrated here that r.f. GDOES also has enormous potential for depth profiling analysis of ultrathin films <10 nm thick, where AES and SIMS have dominant roles. The significant features of r.f. GDOES enabling such analysis arise from the nature of r.f. glow discharge sputtering where samples, both conducting and non‐conducting, are sputtered very stably with Ar+ ions of low energies (<50 eV) and high current fluxes (of the order of 100 mA cm−2). The low Ar+ energy ensures that film sputtering proceeds without significant formation of altered layers, which is a prerequisite for successful depth profiling analysis of ultrathin films at high depth resolution. The high current fluxes allow sputtering to proceed at very high rates of >1 µm min−1, thereby extending the limit of film thickness for analysis to 100 µm. Thus r.f. GDOES, with its unique ability to accommodate depth profiling analysis of films of a very wide thickness range, is expected to play an important role in the field of practical surface analysis. Copyright © 2003 John Wiley & Sons, Ltd.