Heavy Ion Backscattering Spectrometry

Another example regarding shape of the RBS spectrum (Fig. 2.24) is that of ceramic glass — 064NanSi22K2Zn2Cdo,o4 recorded by a beam of 1.9 MeV He particles backscattered at 170°. 

Niwa et al. (1998) used an 8 MeV multicharged carbon or oxygen beam for RBS compositional analysis. The measured results on thin films of Co, Cu, Si, and Ni/Cr of a few nm thickness deposited on carbon substrates by vacuum evaporation or Ar sputtering, demonstrated that the mass resolution is much better for the heavy-ion RBS than for the He-RBS analysis. RBS measurements were also conducted by Mayor et al. (2002) on Nb/Co multilayers using helium as well as lithium ions as shown in Fig. 2.25. Theoretical calculations of the depth resolution are compared with experimental data for RBS yielded about the same or better depth resolution with Li than with helium ions. 

Weidhaas and Lang (2004) carried out the measurements on trace elements on surface by Rutherford backscattering using nitrogen ions. They found that the detection limit for heavy elements e.g., gold in silicon, a surface sensitivity of 10 atoms cm is reached while for medium elements, e.g.. As, Cr, and Fe, the detection limit is 10 atoms cm . HIBS has been used by Banks et al. (1998) for measuring extremely low levels of surface contamination on very pure substrates, such as Si wafers used in the manufacture of integrated circuits. 

---

Heavy ion backscattering spectrometry (HIBS) using ions heavier than He++ with accelerators and detectors similar to those for RBS. 

X-ray emission (PIXE), heavy ion-induced X-ray emission (HIXE), particle-induced y-ray emission (PIGE), Rutherford backscattering spectrometry (RBS), and elastic recoil detection analysis (ERDA). These methods are also multielemental and nondestructive. In general, when ion beam methods are used it should be kept in mind that sulfur-containing matter may be lost during the irradiation, and therefore sufficiently low beam currents should be employed. Also, sample homogeneity is vital since the volume probed by the ions is rather small. 

Ion scattering techniques are useful for characterizing corrosion layers. ISS provides information about the outermost monolayer. ERD (elastic recoil detection) is sensitive to light elements in a heavy matrix and thus provides useful H and Li profile information. Rutherford backscattering spectrometry (RBS), on the other hand,... 

---