On the Composition of the Sputtered Flux from Metal Targets and their Compounds

Abstract

Sputtering of clean metal targets with rare gas ions generally results in a sputtered flux consisting predominantely of neutral ground state metal atoms. This is no longer true for oxides as well as for targets with adsorbed oxygen on the surface. In addition, excited and ionized particles as well as molecules are sputtered under such conditions and their contribution to the sputtered flux can increase by orders of magnitude (1,2). This effect is routinely used in surface analytical techniques, like Secondary Ion Mass Spectrometry (SIMS) to increase the signal strength (2). On the other hand, relatively little is known about the quantitative composition of the sputtered flux under such conditions. Such knowledge is not only important for quantification of SIMS but will also be of importance for more recent analytical techniques like Secondary Neutral Mass Spectrometry (SNMS) (3) and Multi Photon Resonance Ionisation (MPRI) (4). For this reason we have tried to investigate the composition of the sputtered flux for metal targets and some of their compounds under clean conditions as well as exposed to a number of gases (0₂, N₂, NH₃, CH₄).