Hydrodynamic regimes of UV laser ablation of polymers

The applicability of hydrodynamic models for the theoretical description of UV laser ablation of polymers is studied. The plume formation is considered as a first-order like phase transition. This phase transition occurs for strongly absorbing polymers as a surface evaporation and for weakly absorbing polymers as a bulk evaporation. The vapor plume is assumed to be transparent to laser radiation, and its expansion is described by the isoentropic hydrodynamic equations. New analytical expressions for ablation (etch) depths per pulse are obtained, which are in good agreement with the available experimental data. A stationary model for the absorbing plume is constructed.