An experimental technique for the measurement of two-dimensional impurity diffusion profiles was developed. Both the lateral and in-depth extents of dopant diffusion under a mask edge were exaggerated by angle lapping, and the magnified junction contour was delineated by chemical staining. The two-dimensional shape of the junction was reconstructed from the stained contour. A complete diffusion profile, consisting of several iso-concentration contours, could be obtained by measuring the junction shape on a series of samples with increasing substrate resistivities; provided that the doping level in the substrate did not affect the diffusion of the impurity which was being studied. Data on the two-dimensional diffusion of B in Si at 1050C were presented.

R.Subrahmanyan, H.Z.Massoud, R.B.Fair: Applied Physics Letters, 1988, 52[25], 2145-7