Effect of photoacid generator loading and quencher on development pathways in a model chemically amplified photoresist

BackgroundThe development in photolithography proceeds through multiple steps that require precise monitoring to capture each procedure. Although standard sensitivity analysis defines the static dose-to-clear endpoint, these conventional metrics fail to resolve the time-dependent physical and chemical pathways that dictate final pattern quality.AimWe aim to determine the effect of photoacid generator (PAG) loading and quencher additives on the sensitivity and time-resolved development pathways of a model chemically amplified photoresist exposed under extreme ultraviolet (EUV).ApproachInitial sensitivity analysis on silicon substrates established a dose-to-clear reference window for all resist formulations. Using this defined exposure range, a quartz crystal microbalance with resistance monitoring tracked real-time dissolution kinetics from low doses through full clearance in a diluted developer.ResultsDevelopment behavior was categorized into four distinct modes based on resonant frequency and motional resistance. Increasing PAG concentration or exposure dose systematically shifted the observed development behavior from diffusion-dominated uptake toward rapid bulk dissolution.ConclusionsSamples exhibiting similar final thicknesses can evolve through fundamentally distinct time-resolved development pathways. Here, we report a model photoresist formulation that transitions from swelling (at 5 wt.% PAG) to nonswelling behavior (at 10 and 20 wt.% PAG) during dissolution in a diluted developer. In addition, resists containing a photo-decomposable quencher required a higher exposure dose than their quencher-free counterparts to achieve similar dissolution behavior. Ultimately, these findings demonstrate that real-time kinetic measurements are essential to capture the critical, transient interfacial states that govern EUV resist dissolution.