Interface analysis using elastic scattering in the transmission electron microscope: Application to the oxidation of silicon

Abstract

We describe the method of Fresnel fringe contrast analysis and discuss the results obtained by applying the technique to the analysis of the oxides first formed on silicon during wet oxidation. The accuracy of the method is limited at present by the effects which inelastic scattering has on the microscope images. Although these effects are hard to quantify, we show that accurate results can be obtained concerning the sharpness or diffuseness of the Si/SiO, interface at the atomic level. Combining the results obtained by this method with those found by using high-resolution electron microscopy for oxides of different thicknesses we are able to conclude that there is a SiO, layer of probably 0.25 nm present during the first stages of oxide growth, but that a further 0.5 nm of crystalline oxide develops well after the start of the oxidation, when the oxide layer is between 2 and 4 nm thick. The implication of these results in relation to the various mechanisms for silicon oxidation which have been proposed are discussed briefly.

Gettering of Au to dislocations and cavities in silicon

“…After the 850°C annealing ϳ96% of the implanted Au is located at the H-induced cavities as shown in Fig. 12 Further TEM observations of some cavities ͓dark, poorly faceted features in Fig. Indeed, for a longer annealing time ͑e.g., 48 h͒ at 850°C, essentially all the implanted Au is driven from near-surface traps to the cavities.…”