Contamination control in 300 mm foundry

In the normal wafer process flow, the contamination problem must not happen except a little of RD research lots. In 300 mm fab, we put multiple lots in a carrier to improve the operation efficiency. This feature reduces the cost but increase the risk of contamination disaster very much. A lot coated with the photo resist must be prevented from entering a furnace. The mixed frond-end and back-end processed lots could have contamination issue after study. New research material, like copper, will affect the yield if they are not separated with aluminum. All of them are the scope of the contamination control.