Sputtering electrical atomization

This technique can be applied to samples prepared for study by scanning electron microscopy (SEM). When subject to impact by electrons, atoms emit characteristic X-ray line spectra, which are almost completely independent of the physical or chemical state of the specimen (Reed, 1973). To analyse samples, they are prepared as required for SEM, that is they are mounted on an appropriate holder, sputter coated to provide an electrically conductive surface, generally using gold, and then examined under high vacuum. The electron beam is focussed to impinge upon a selected spot on the surface of the specimen and the resulting X-ray spectrum is analysed. 

A wide variety of process-induced defects in Si are passivated by reaction with atomic hydrogen. Examples of process steps in which electrically active defects may be introduced include reactive ion etching (RIE), sputter etching, laser annealing, ion implantation, thermal quenching and any form of irradiation with photons or particles wih energies above the threshold value for atomic displacement. In this section we will discuss the interaction of atomic hydrogen with the various defects introduced by these procedures. 

An example of the ability of atomic hydrogen to passivate the electrically active damage created by Ar2+ ion beam (6 keV) bombardment of n-type (N = 1.5 x 1016 cm-3) Ge is shown in Fig. 8. In this case the Ge was sputter etched for 10 min. at 24°C or 100°C and the spectrum recorded using an evaporated Au Schottky contact. The damage created by the sputtering caused the rather broad peak of Fig. 8(i), which was unaffected by a 30 min. anneal at 200°C in molecular hydrogen. Heating in atomic... 

Secondary ions return to the sample surface through the influence of the electric field at the cathode. Individual atoms and clusters of atoms undergo collisions that may dissociate the clusters and redeposit material at the surface. A percentage of these sputtered atoms, however, diffuse into the negative glow for subsequent excitation and ionization. 

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