The generation of acids in chemically amplified electron beam resists needs the cation radicals of base polymer and electrons, both of which are generated via the ionization of base polymer on the exposure. This leads to the separation of several nanometers between protons and counter anions. The separation deserves special attention from the viewpoint of resolution blur. The distribution of counter anions was examined with a simulation based on the Smoluchowski equation. (C) 2003 American Vacuum Society.