Stochastic exposure kinetics of extreme ultraviolet photoresists: Trapping model

The mechanism of extreme ultraviolet resist exposure is still in debate, with various competing mechanisms proposed. Here, three different continuum exposure models and two stochastic exposure models are compared, using predictions of acid concentration and yield as a function of dose and photoacid generator (PAG) loading. The models studied are a stochastic excitation model (and its continuum counterpart), a stochastic PAG trapping model (and its newly derived continuum counterpart), and the continuum Higgins competing traps model. These models produce different predictions for acid concentration as a function of dose and PAG loading, and for acid yield as a function of PAG loading. Thus, it may be possible to use experimental data to differentiate between these mechanisms, though the possibility of multiple simultaneous mechanisms cannot be ruled out.