Ammonia sorption outgassing and cross contamination ability of Entegris FOUPs evaluation and its volatile acids comparison

Real Time AMC Monitoring with Novel Chemical Ionization Mass Spectrometry at Single-Digit pptv Concentrations

“…The wafers were removed from the FOUP on day 7 promoting airborne VOC concentrations to drops drastically. Outgassing behavior of molecules such as HF, HCl, and ammonia was reported earlier [10] that report evidence of outgassing contaminants once the source is removed and the FOUP is purged; in this case the contamination source was removed but no purge was applied. The PGMEA & HBA behavior observed here, when eliminating the contamination source (wafer removal) demonstrates a significant decrease of the contaminant concentration at each monitored step until reaching a new equilibrium on day 14 th (312h), in which; neither of these two compounds reached background levels, confirming the tendency to adhere to the surfaces.…”

Review—Airborne Molecular Contamination: Recent Developments in the Understanding and Minimization for Advanced Semiconductor Device Manufacturing

“…Following their previous works on the sorption of volatile acids (HCl and HF) onto the polymeric surfaces of various FOUPs materials and the potential of their outgassing to cause cross-contamination, Gonzales-Aquirre et al ( 2019) 44 recently studied the characteristics of ammonia in the air. They chose to use a Cr-coated wafer for the sorption test, knowing that Si wafers are not sensitive to ammonia.…”

Adsorption and desorption kinetics of airborne ammonia on chromium-coated wafer in cleanroom depending on humidity and NH3 concentration

“…The Cr-coated wafer now serves as a reliable test-vehicle to investigate the NH3 cross-contamination between FOUPs to wafers. Gonzalez et al [9] performed the experiments to evaluate the NH3 transferred on Cr-coated wafer from intentionally contaminated FOUPs (PC and EBMCNT) for an equivalent contamination occurrence of 1.5 ppmv (part-per-million-volume) of NH3 in FOUPs' atmosphere. After intentional contamination time of 24h, most of the initial concentration was sorbed by inner FOUP surfaces.…”

“…In order to minimize the deposition of particles and AMCs, the front opening unified pods (FOUPs) were introduced as a controlled-minienvironment to protect the processed wafers during transport and storage steps. However, the FOUPs-walls are made of polymers, which potentially outgas previous sorbed-NH3 to the FOUPs' atmosphere, leading to NH3 cross-contamination on stored wafers [9]. The experiments of NH3 crosscontamination between polymeric FOUPs and wafers, however, require an appropriate metal-coated wafer 2 (named as test-vehicle) with a sensitive surface to the contaminant.…”