A Physically Constrained Microbubble-Assisted Breakdown Model for Electrostatic Discharge in a Pressurized Chemical Delivery System

Electrostatic discharge (ESD) in fluoropolymer-lined Standard Clean-1 (SC-1) delivery systems is a reliability concern in semiconductor wet processing, yet its physicochemical pathway remains uncertain. This field-based study investigated ESD-damaged perfluoroalkoxy alkane (PFA)- and polytetrafluoroethylene (PTFE)-lined components using operational observations, post-failure characterization, and first-order Townsend–Paschen analysis to formulate a physically constrained working hypothesis rather than to verify a unique root-cause mechanism. Damaged PFA/PTFE components exhibited tracking paths, pits, micro-voids, and re-solidified rims consistent with localized electrical and thermal damage. Prolonged N2 pressurization increased the measured potential from approximately 0.3 to 3 V over 6 h, whereas venting reduced it; a static 30 kV test did not reproduce the field failure. Periodic depressurization to atmospheric pressure at 3–4 h intervals and installation of conductive grounding points were each followed by an absence of observed ESD events during the corresponding operating periods. A Microbubble-mediated Townsend–Paschen Breakdown (MTPB) hypothesis is therefore proposed, in which interfacial charging supplies charge while transient mixed-gas cavities provide candidate gas-phase discharge sites. A first-order N2 Paschen calculation places a 2.2–3.5 μm effective gas gap near the minimum-breakdown region, with a calculated minimum voltage of approximately 358 V. This MTPB framework provides a physically constrained and testable explanation for the observed field behavior and a basis for future direct validation.