Geometric-structure-dependent charging, caused by the difference in the angular distribution functions for electrons and ions, has been investigated using a Kelvin probe. The experimental data shows that the magnitude of the residual charge accumulated on the surface during plasma processing is a function of the aspect ratio. The surface voltage is not a monotonic function of the etch depth, but has a maximum at a certain depth. The surface voltage considerably reduces vs time for deep holes (thin remaining dielectric), while it was relatively constant for shallow holes. These results suggest that there are two possible channels for the surface-charge leakage, along the surface and between the bottom of a hole and the Si substrate. (c) 2005 The Electrochemical Society. [DOI: 10.1149/1.2130311] All rights reserved.