The Impact of Fluidic Packaging Cleanliness on finFET Biosensing

CMOS-compatible finFET biosensors offer promising potential for enabling high-throughput DNA and protein sequencing with single-molecule resolution. However, realizing this potential requires careful control of factors that can affect the sensor performance. In this study, we investigated how the cleanliness of the fluidic packaging, specifically the flow cell and adhesive materials used for device assembly, affects the performance of these biosensors. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) analysis revealed organic contamination introduced by the flow cell assembly, particularly from long-chain hydrocarbons and adhesive residues, resulting in limited biosensor DNA signal. We evaluated two double-sided adhesive materials for their influence on the biosensor sensitivity and implemented a systematic cleaning protocol, comprised of acetone/isopropanol (IPA) rinsing and O₂ plasma treatment, to remove the fluidic packaging contamination and improve the finFET DNA signal. Optimal results were observed at 60 seconds of plasma treatment exposure in combination with the lower-contaminant adhesive. Overall, these findings highlight the critical importance of fluidic packaging cleanliness for achieving reliable biomolecular detection with finFET-based biosensors.