Improved reproducibility in scanning capacitance microscopy for quantitative 2D carrier profiling on silicon

Abstract

UV/ozone and wet chemical oxides are compared in terms of reproducibility for scanning capacitance microscopy (SCM). The epitaxial staircase test structure consisted of n-type doped layers with concentrations ranging from 5×10 14 to 5×10 19 cm −3 grown on a uniformly doped Si substrate. Either metal- or diamond-coated probes were used to compare their respective performance. The influence of the tip-coating layer on the reproducibility of measurements with regard to the oxide quality is discussed. In a single scan, the signal variation is mainly owing to the oxide quality and the UV/ozone oxidation method is found to be of higher quality than wet chemical oxidation. In contrast, in multiple scans, the signal variation is strongly dependent on the tip wear and it is clearly evidenced that the diamond-coated probe is suitable for its stability and reliability. The combination of the UV/ozone oxidation process with the use of a diamond tip is an efficient compromise for improved reproducibility of SCM measurements on silicon.