Basic Characteristics of Beam Position Drift and Field Stitching Error Caused by Electron Beam Column Charging

The beam drift caused by column charging and its influence on field stitching error were experimentally studied in an electron optical column with a contaminated inner surface. The raw drift characteristics indicate that secondary electrons with an energy lower than that of an electron accelerated by a voltage equal to the deflection voltage move from the substrate to the electrode surface and are the main cause of charging. Pattern writing was performed to examine field stitching error. For a continuously moving stage, the errors are roughly as large as the drift and their direction and magnitude change dramatically between neighboring rows of fields. The results on stitching error can be explained very well by considering the details of the writing procedure and the drift characteristics.