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The scanning microwave microscope is used for calibrated capacitance spectroscopy and spatially resolved dopant profiling measurements. It consists of an atomic force microscope combined with a vector network analyzer operating between 1-20 GHz. On silicon semiconductor calibration samples with doping concentrations ranging from 1015 to 1020 atoms/cm3, calibrated capacitance-voltage curves as well as derivative dC/dV curves were acquired. The change of the capacitance and the dC/dV signal is directly related to the dopant concentration allowing for quantitative dopant profiling. The method was tested on various samples with known dopant concentration and the resolution of dopant profiling determined to 20% while the absolute accuracy is within an order of magnitude. Using a modeling approach the dopant profiling calibration curves were analyzed with respect to varying tip diameter and oxide thickness allowing for improvements of the calibration accuracy. Bipolar samples were investigated and nano-scale defect structures and p-n junction interfaces imaged showing potential applications for the study of semiconductor device performance and failure analysis. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) doping profiles of layered, differently doped, n-step Si homostructures were measured by scanning capacitance microscopy (SCM) and scanning Kelvin probe microscopy (SKPM). The calibrated doping concentration of the n-type Si layers was in the range of 4.2×1014 cm-3 to 1.7×1019 cm-3. For the SCM images, the measured ΔC/ΔV signals were converted to 2D doping concentrations using the NIST FASTC2D program. To compare the SCM-based 2D dopant profiles with those obtained by SKPM, a contact potential difference (CPD) between a probe tip and the Si sample surface was measured with SKPM. Using the relation between a work function and a doping concentration of Si, the doping concentrations were extracted from the measured CPD. The SCM results had good agreements with the calibrated data, but the SKPM results showed some differences due to the presence of the top native oxide layer. [ABSTRACT FROM AUTHOR]

Controlled polishing procedures were used to produce both uniformly doped and p-n junction silicon samples with different interface state densities but identical oxide thicknesses. Using these samples, the effects of interface states on scanning capacitance microscopy (SCM) measurements could be singled out. SCM measurements on the junction samples were performed with and without illumination from the atomic force microscopy laser. Both the interface charges and the illumination were seen to affect the SCM signal near p-n junctions significantly. SCM p-n junction dopant profiling can be achieved by avoiding or correctly modeling these two factors in the experiment and in the simulation. [ABSTRACT FROM AUTHOR]