Imaging doped regions in a semiconductor with very low energy SEM and Auger electrons.

Regions of n(+) and p(+) semiconductors doped to 2.5 x 10(20) and 8x10(19) cm(-3) respectively on n-type silicon substrate have been imaged in a scanning electron microscope modified for use into a cathode lens mode operating in the region of 110,000 eV. The highest contrast with respect to that of the n-type silicon has been obtained from the n(+) region followed by the p(+). Further, the n(+) area shows a maximum contrast at about 5-20 eV, while the contrast from the p+ area shows a maximum at about 300 eV. Imaging of the sample in UHV was also investigated in parallel with AES of the differently doped regions. The AES revealed the presence of a graphitic carbon surface layer across the sample. The effects of altering the surface conditions with a Cr surface layer were also investigated.