STOCHASTIC SCATTERING IN CHARGED-PARTICLE PROJECTION SYSTEMS - A NEAREST-NEIGHBOR APPROACH

Image blurring as a result of stochastic particle-particle interaction s has been investigated for projection electron- and ion-beam lithogra phy systems. A comparative analysis of the currently available analyti cal theories is presented. The results from these theories are also co mpared with Monte Carlo simulation results and experimental data. Larg e variations in results and serious disagreements between the differen t theoretical approaches are found. We have formulated a new theory on the basis of a simple, analytical approach that overcomes most of the difficulties experienced by earlier theories with two key concepts: c onsideration of nearest-neighbor interactions only, and a randomizatio n length, over which the interactions are correlated. Our model displa ys satisfactory functional and numerical agreement with Monte Carlo si mulation results over a large range of beam currents, as well as with the only available experimental data. The physical basis of our model also enables us to understand the origins of the discrepancies arising from earlier theories. (C) 1995 American Institute of Physics.