Problems in using surface analysis techniques for the depth profiling of microelectronic materials

Practical problems associated with the depth profiling of impurity distributions in silicon and silicon dioxide are illustrated for several widely used surface analysis techniques as applied at a number of laboratories. The methods used for depth profiling were Rutherford backscattering spectroscopy, Auger electron spectroscopy and X-ray photoelectron spectroscopy. The profiles measured for zinc-implanted silicon displayed good overall agreement when presented on a normalized scale, but when presented on an absolute basis displayed large discrepancies attributed to matrix effects and instrumental artifacts. An examination of some typical analysis craters by optical interferometry, stylus profilometry, and scanning electron microscopy revealed severe redeposition of the sputtered material, asymmetrical cavities with concave or convex bottoms, and severe undercutting at material interfaces.