Experimental and theoretical investigations of parameters controlling line profiles in electron-beam lithography

An experimental and theoretical investigation of the more important parameters which affect the developed profile shape in electron-beam lithography is described. The theoretical approach is based on a Monte Carlo method of simulating electron scattering in the substrate to calculate the energy dissipation in the electron resist layer for a scanned electron beam. The current distribution in the beam is taken into account with a separate convolution procedure. The developed profile shape is obtained with a threshold solubility model which predicts a threshold energy density of 6.58 × 1021 eV/cm3. A development simulation using the string method is used to predict the profile shape when the development process becomes a significant factor at a resist thickness of about 0.7¿m. Finally the proximity effect is investigated by means of adjacent line experiments and compared with the predictions of the threshold solubility model.