Wafer ambient control for Agile FAB

The "Wafer Ambient Control Box" has been developed for minimizing the influence of chemical contaminants such as acidic gas, basic gas, organic molecules, and also humidity. It consists of a ULPA filter, chemical filters, SPE films (dehumidifier), and a fan. We applied the Box to the Al interconnection process. The acidic gas adsorbed on the wafer causes corrosion defects. By keeping the wafer in the "Wafer Ambient Control Box", Al lines were prevented from corrosion because the chemical filter trapped the acidic gas desorbed from the wafer. We also applied the humidity controlled one to the poly-Si plug process. The poly-Si/Si contact resistance was equivalent to that processed continuously even though it was kept for 67 h before poly-Si deposition.