As the resolution of optical lithography reaches 0.35 mu m and below, linewidth can no longer be predicted by aerial image alone. Accordingly, we incorporate thin-film interference within the resist/substrate stack and postexposure bake diffusion effects in our latent image formation model. The impact of resist thickness and antireflective coatings on optical proximity effect and process latitude has been examined. Taking various optical effects into account, our simulation matches the experimental data very well. Using the enhanced simulation tool, we have studied the practical process window and possible enhancement techniques. (C) 1995 American Vacuum Society.
