The influence of plastic properties of the probe tip/Si contact on spreading resistance analyses

Analyses of spreading resistance measurements in Si samples with dopant profiles of the dopant sequence lowly doped on highly doped yield unreliable results if the dopant profiles are extremely steep or ultra-shallow. Reasons for this behavior are seen in effects of penetration of the probe tips into the Si sample and in the presence of a zone of a metallically conducting Si phase beneath the probe tip. Atomic force microscopy has been used to investigate the geometry of probe tip indents and scanning electron microscopy to investigate the geometry of the probe tip itself. Results of loading-unloading experiments by means of nanoindentation with a conventional spreading resistance probe tip as indenter enable us to estimate the depth of the metallic Si phase zone. It ranges from about the fourfold up to the sevenfold of the residual depth after unloading the probe tip. (C) 1996 American Institute of Physics.