Tip-to-Sample Distance Dependence of $dC/dZ$ Imaging in Thin Dielectric Film Measurement

概要

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We have developed scanning capacitance microscopy (SCM) with a self-sensing conductive probe that can be used to obtain static capacitance ($dC/dZ$) images by virtue of the vertical vibration of the probe tip. This technique for $dC/dZ$ imaging can delineate features, such as thickness variations or fixed charge distributions, within a dielectric film and provide a lateral resolution comparable to that of simultaneously obtained topography images. In this work, we have experimentally revealed that the lateral resolution of a $dC/dZ$ image is insensitive to the probe tip amplitude, and the sensitivity of $dC/dZ$ images strongly depends on the distance of the gap between the probe tip and the sample surface. These results and the force–distance characteristics of the self-sensing conductive probe indicate that the $dC/dZ$ signal is mostly determined by the probe tip–sample capacitance and also that the spatial resolution of $dC/dZ$ imaging is not affected by the surface-adsorbed meniscus layer under a vacuum environment measurement. Finally, we have demonstrated sub-10-nm spatial resoluton in $dC/dZ$ imaging for thin dielectric film measurement.
2008-02-25