Experimental aspects and modeling for quantitative measurements in scanning capacitance microscopy

Abstract

In this article we discuss the reliability of a quantification method for scanning capacitance microscopy (SCM) measurements based on the calculation of a calibration curve. We demonstrate that an accurate control of the conductive tip coating stability, low temperature oxidation and Si–SiO2 interface microroughness allows one to fabricate a nanometric metal-oxide-semiconductor device (nanoMOS), whose dC∕dV-V characteristics measured on a set of different concentration levels can be reproduced by simulation of an ideal nanoMOS with the realistic three-dimensional geometry. We also studied the impact of tip coating (metal and conductive diamond coated tips) and oxidation method (wet and UV∕ozone oxides) on the reproducibility of the measured SCM signal for different concentration levels both on p- and n-type Si staircase calibration samples, and we demonstrated that the UV∕ozone oxidation associated with the use of a diamond tip is the best solution. The experimental calibration curve obtained by this choice is well fitted by the calculated calibration curve. The maximum experimental errors affecting the measured SCM signal depending on doping concentrations have been determined and these errors have been used to estimate the maximum errors on the concentration values calculated by applying the theoretical calibration curve.