The electrical properties of the oxide films thermally grown from polycrystalline silicon have been examined. Without the electrode shape effects the films can sustain high electric fields (6.5 MV/cm) and do not trap a significant number of electrons at those fields. The high oxide leakage current found in the bumpy injection electrodes is correlated to the shape of the bump. The electric field distribution between two parallel bell‐shaped electrodes was computed numerically. Solutions suggest that the field enhancement cause by the geometrical shape of the injection electrode is the major cause for the observed high oxide current in the polycrystalline silicon‐(poly‐oxide)‐polycrystalline silicon structure.