Plastic containers contamination by volatile acids : accumulation, release and transfer to Cu-surfaces during wafers storage

摘要

This study addresses the problematic of volatile acids accumulation in plastic containers (i.e. FOUPs) and, their later release and transfer during wafers storage to sensitive layers as Cu-surfaces. Experiments have been carried out by the intentional contamination of a type of commercial FOUPs with HF, HCl or HBr. Results show the very great ability of plastic containers to trap these volatile contaminants and allow to rank HF as less absorbed than the 2 other gases. On the other hand, the storage of Cu-wafers inside contaminated containers have demonstrated the significant cross-contamination of volatile acids from the FOUP to Cu surfaces by molecular outgassing. Results have allowed to evaluate concentrations outgassed in the FOUP atmosphere as: HF > HCl > HBr. Thereby, F and Cl levels close to 1E+14 at/cm~2 have been fast reached highlighting the potential detrimental impacts which can occur on Cu-layers by a accumulation/release process of acids in FOUPs.