Spatially resolved dopant profiling of patterned Si wafers by bias-applied phase-imaging tapping-mode atomic force microscopy

Tapping-mode atomic force microscopy was used to spatially resolve areas of different doping types on Si wafers patterned by photolithography and subsequent ion implantation. Application of a direct current dc bias between cantilever and sample during measurement induced a change in the tapping-mode phase contrast depending on the dopant type of the scanned sample area. This allowed the direct identification of areas of different doping types. Additional measurements on Au samples demonstrate a direct correlation between bias-induced Coulomb force and resulting phase change allowing the conclusion that the observed phase contrast results from dc bias-induced band bending changes.