On the reliability of scanning probe based electrostatic force measurements

The dimensions of semiconductor devices rapidly decreasing, the detection and control of spatial inhomogeneities of material properties on a sub-μm scale becomes essential.For mapping various electrical properties with nearly nm-resolution, scanning probe techniques appear to be ideally suited. However, data evaluation always involves a transfer from measured to real properties by a device depending convolution procedure.We report on our results for different modes of electrical measurements, namely scanning Kelvin probe microscopy (SKM) and scanning capacitance microscopy (SCM) on various sample systems discussing the influence of experimental parameters. In addition, results of finite element simulations on this topic are presented.It turns out that the averaging function correlating real and measured data may appear quite simple, thus making a reliable reconstruction possible. On the other hand, the existence of surface charges can drastically change the results.