Shot noise effects are important to take into account both in the design of resists for lithography and in the design of lithography tools. The statistics of electron or photon arrival gives rise to dose variations, which translate to variations in the size of written features. It is possible to model the shot noise effects in an analytical equation, which shows the influence of all relevant parameters. The sequence of subsequent events in the resist: Secondary electron creation, acid generation, and acid diffusion are incorporated in the model. The model then allows the evaluation of the minimum resist sensitivity necessary for a certain required critical dimension control. (c) 2005 American Vacuum Society.