TRIDIMENSIONAL CHARACTERIZATION OF VOIDS IN SELF-ANNEALED IMPLANTED SILICON USING ELECTRON HOLOGRAPHY

The characterization of defects produced during self annealing implant ation of P+ ions in silicon is of great interest for the realization o f good quality p-n junctions in silicon and to understand the peculiar ity of beam-solid interactions occurring during implantation performed under conditions of extremely high current and power density [1-4]. H igh-resolution electron holography is employed here to study the three -dimensional configuration of sphere-like cavities obtained by 100 keV P+ ion bombardment of a silicon wafer using a beam with a power densi ty of 15 W/cm(2), respectively 27 W/cm(2) for 4 sec. Phase difference amplification techniques have been used to obtain maps in which the el ectron phase distribution indicates the thickness contours. From these maps a qualitative topography of the cavity shape as well as measurem ents of its depth variations are obtained. Electron holography can als o be employed to display the various different internal geometries tha t a void structure can assume.