Non-methane hydrocarbons from integrated semiconductor manufacturing processes: Assessments of chemical footprints, emissions factors, and treatment efficiency

Abstract

Non-methane hydrocarbons (NMHCs) are harmful chemicals produced from organic solvent use in industrial sectors. Wafer fabrication process from semiconductor fabs utilizes many organic solvents that could intensify NMHCs emissions. This study comprehensively assessed the Total NMHCs (TNMHCs) emissions from 141 exhaust pipes of 59 semiconductor fabs in Taiwan with regards to their concentrations, emission factors, treatment efficiency, and total chemical footprint (ChF) for human toxicity. Throughout three semi-processes of wafer fabrication, the raw emitted NMHCs concentrations were in the ranges of 3–131.25 ppm, 8–288 ppm, and 23–567 ppm for wafer cleaning (WC), photoresist stripping (PS), and photolithography (PL). The average untreated TNMHCs emissions rate was 0.2 ± 0.08 kg/h < 1.72 ± 0.09 kg/h < 2.55 ± 0.08 kg/h in the order of WC < PS < PL, whereas the average treated emissions rates were in the ranges of 0.09–0.10 kg/h. The estimated emission factors for wafer fabrication process were 0.30 ± 0.04 kg/kg, 0.07 ± 0.02 kg/piece, and 1.37 ± 0.11 kg/m2. Further assessment has found that zeolite rotary concentrator and regenerative thermal oxidations (ZRC + RTO) possess the highest overall performances for abating TNMHCs emission with efficiency ranges of 92.31–99.56% (n = 66). ZRC + RTO could produce outlet TNMHCs within the ranges of 2.94–5.56 ppm, which were lower than the upcoming revised emission standard of <14 ppm. ChF analysis of the estimated NMHCs species showed that PL had the largest untreated ChF, followed by PS, and WC of which the ChF were 15.72, 7.05, and 6.79 cases. The speciated ChF was dominated by acetone, methanol, and isopropyl alcohol from three semi-processes. The ChF analysis in this study could potentially become a supporting instrument for industrial sectors to determine the major contributing processes and chemicals with adverse impacts to human health.