Wear characteristics of diamond-coated atomic force microscope probe.

Sub-10 nm resolution can be obtained in scanning capacitance microscopy (SCM) if the probe tip is approximately of the same size. Such resolution is observed, although infrequently, with present commercially available probes. To acquire routine sub-10 nm resolution, a solid Pt metal probe has been developed with a sub-10 nm tip radius. The probe is demonstrated by SCM imaging on a cross-sectioned 70 nm gatelength field-effect transistor (FET), a shallow implant (n+/p, 24 nm junction depth), and an epitaxial staircase (p, ∼75 nm steps). Sub-10 nm resolution is demonstrated on the FET device over the abrupt meeting between a silicon-on-insulator oxide layer and a neighboring Si region. Comparable resolution is observed on the implant structure, and quantitative SCM dopant profiling is performed on it with sub-10 nm accuracy. Finally, the epitaxial staircase structure is quantitatively profiled demonstrating the accuracy obtained in quantitative profiling with the tips.

Sub-10 nm lateral spatial resolution in scanning capacitance microscopy achieved with solid platinum probes

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 choi...

Experimental aspects and modeling for quantitative measurements in scanning capacitance microscopy

Scanning capacitance microscopy (SCM) has been performed both in cross-sectional and in angle-beveling configurations on ultranarrow B spikes with a full width at half-maximum smaller than the SCM probe diameter. The dependence of the SCM response on the magnification factor has been studied, demonstrating an improvement both in terms of spatial resolution and sensitivity by angle-beveling sample preparation. The range of applicability of the direct inversion approach for the quantification of SCM profiles on ultranarrow B spikes has been assessed for high doping spikes thicker than 3 nm and measured on bevel. Two-dimensional simulations allowed the reproduction of all the main features of the experimental SCM profiles.

Scanning capacitance microscopy on ultranarrow doping profiles in Si

We addressed issues related to quantitative carrier profiling by scanning capacitance microscopy (SCM) on doped layers with different dimensions, starting from thick (∼5 μm) uniformly doped Si layers down to Si/Si1−xGex/Si quantum wells with nanometre width. We preliminarily discuss the influence of the SCM hardware on the quantification, by comparing the analyses performed on Si calibration standards with two different atomic force microscopes, i.e. DI3100 by Veeco and XE-100 by PSIA, equipped with different SCM sensors. Furthermore, concentration sensitivity and spatial resolution are deeply discussed considering measurements on special designed samples containing quantum wells of Si0.75Ge0.25 layers strained between Si films. Measurements were taken on sample cross-sections and on bevelled samples. A nanometre SCM spatial resolution was demonstrated not only in terms of signal sensitivity, but also in terms of quantitative majority carrier profiling.

Carrier distribution in quantum nanostructures by scanning capacitance microscopy

Diamond-coated cantilevers have been used for scanning capacitance microscopy (SCM) as an alternative for metal-coated cantilevers in order to improve the stability of probes. It is shown that the diamond-coated probes produce adequate intensity of dC signal and high contrast for both p-type and n-type silicon samples and also provide superior endurance characteristics to metal-coated probes. Due to the robustness of the diamond-coated probes, we are able to evaluate the reproducibility of measurements and the homogeneity of the ultrathin oxide for both dry oxidation (heated up to 300 °C in air under ultraviolet illumination) and wet oxidation (immersed into a hydrogen peroxide solution at 70 °C). The dry oxidation shows better reproducibility, while the wet oxidation shows better homogeneity. Finally, comparison of SCM with secondary ion mass spectrometry measurement shows that diamond-coated probes can be used at least for one-dimensional quantitative SCM measurements without any significant effect of d...

Hidehiko Yabuhara

Papers

Scanning capacitance microscopy measurements using diamond-coated probes