Developer temperature effect on negative deep ultraviolet resists: Characterization, modeling, and simulation

We consider the effect of developer (solvent) temperature in the dissolution of both the exposed and unexposed parts of the resist. The spin-formatted resist film tends to have macromolecules oriented parallel to the substrate surface. The orientation of the resist macromolecules introduces an anisotropic component to the etch rate: higher in the direction parallel to the substrate surface and lower in the perpendicular one. We performed a series of experiments on resist-coated Si wafers using a stepper and a deep ultraviolet source at 248 nm using SNR-248 negative resist. We obtained scanning electron micrographs for various developer temperatures. The variation of the lateral etch rate manifested itself in sidewall profile slopes and is compatible with the entropy directional flow. Simulation using the Cellular Automata model predicted identical results. (C) 1997 American Vacuum Society.