Physical mechanism of oxide interfacial traps, carrier mobility degradation and series resistance on contrast reversal in scanning-capacitance-microscopy dopant concentration extraction.

In this letter, the contrast reversal effect in scanning-capacitance-microscopy (SCM) dopant concentration extraction is investigated both theoretically and experimentally. The shift of the turning point in the nonmonotonic response of peak dC/dV signal versus dopant concentration to higher dopant concentrations is explained by the difference of the capture/emission time constant of the interface states and the series resistance of the semiconductor sample. This is verified by comparing the experimental SCM measurements with the simulated peak dC/dV profile on a p-type multiple dopant step sample. The contrast reversal effect, which affects the accuracy of dopant concentration extraction using the SCM peak dC/dV signal, can be minimized by using an overlying oxide with good interfacial quality and a semiconductor sample of low series resistance. [ABSTRACT FROM AUTHOR]