Correlation Between Surface Topography and Static Capacitance Image of Ultrathin SiO₂ Films Evaluated by Scanning Capacitance Microscopy

Abstract

We performed scanning capacitance microscopy (SCM) using a self-sensing conductive probe to investigate the relationships between the surface morphology, oxide thickness variation, and subsurface depletion layer of ultrathin SiO 2 films on p À -Si substrates. First, upon analyzing the two-dimensional cross-correlation between dC=dZ images and simultaneously obtained topography images, we found that the dopant concentration of the Si substrates affects the correlation, and this can be attributed to the spatial inhomogeneities in the depletion layer formed by the SCM probe tip. We considered these depletion layer inhomogeneities to reflect the individual dopant distribution within the substrates. Second, from the surface roughness and spatial deviation of the dC=dZ images as well as the cross-correlation analysis results, we concluded that the surface roughness directly corresponds to the spatial variation in SiO 2 film thickness.