Scanning electron microscopy of dopant distribution in semiconductors

We show that, in scanning electron microscopy, it is possible to use the secondary electrons produced by the backscattered electrons to obtain chemical information on the dopant distribution in Sb-implanted silicon. Theoretical investigations and experimental data concur to point out that the resolution of the method is defined by the probe size—values of 1 nm or even lower are possible in the present instruments—while the contrast depends on the electron range and on the boundary conditions. A proper choice of beam energy and boundaries of the doped layer may allow a sensitivity below 1%, suitable to characterize the high-dose near-surface region of the ultrashallow junctions in cross-sectioned bulk specimens.