Measurement of Sputtering Yields of SiO2-Si Samples Sputtered by O2+ and Cs+ Bombardment in SIMS Analysis.

Abstract

Much data on sputtering yields under the bombardment of non-reactive ions such as Ar+, Ne and other ions is avaibable, at present, but not for the sputtering of the samples in secondary ion mass spectrometry (SIMS) analysis. In the analysis, chemically active primary ion species such as O2+, Cs+ and O- ions have been used widely, and thus the primary ion species are im-planted into the sample surface layers. As a result, the mixing layers (compounds), composed of primary ion species and sample elements are formed during the subsequent sputtering processes. Therefore, from a practical perspective, it is necessary to measure the sputtering yields of the target having a different constitution from the original under chemically active ion sputtering. This paper presents the sputtering yields of Si (Ys) in an oxidized SiO2 layer, and the Si sub-strate, sputtered by cesium (Cs) and oxygen (O2) ion beams. The quantitative sputttering yields were measured from sputtered crater volume after sputtering, and from sputtering rate under ion bombardment. The values of Ys for SiO2 layer during Cs+ and O2+ bombardment at 15 keV measured by spur tering rate method were respectively 1.3 and 2.4 atoms /ion. For Si substrate, the values were 2.7 and 5.4 atoms/ion respectively.