As we mentioned, the technicians don’t handle the wafers directly. The wafers are located in squared boxes called lots, which holds 25 wafers each. On Intel fab, lots carrying wafers using aluminum on their metal layers are black, while wafers using copper on their metal layers are orange.
click to enlarge Figure 7: A lot (this is an older lot model and was located on the small Fab18 museum).
When the technician inserts the lot in the processing tool, the machine will open it, take each wafer, process it and then put the processed wafers back in the lot.
From one clean room to the other the lots are carried automatically by a set of tracks. On Figure 6 you can see a track (like a monorail train track) on the ceiling. That is where the lots are carried.
In some cases the track system brings the lot directly inside a machine, not needing an employee to put the lot inside it.
For each machine there is a screen where the technician can see what the machine is doing and which wafers are being processed.
As we mentioned, the final product from Fab18 is not ready-to-use CPUs, but wafers containing several chips. These wafers after being manufactured are sent to test and assembly factories located in other countries like Malaysia, Costa Rica and Philippines, where they cut the wafer, put terminals and a body on the chips, test them, label them and then ship to the market.
