Fab18 was established in 1999 and at that time produced Pentium III wafers. It was upgraded to the 90 nm process and now it produces wafers for Pentium 4 CPUs, chipsets and flash memories. There are 3,700 people working there.
Before continuing, we’d suggest you to read our tutorial How Chips are Manufactured, for a better understanding of what we are going to talk from now on.
Due to its huge size – Fab18 has the size of two soccer courts – and to the very high cost of building and maintaining a clean room, instead of the entire factory being a huge clean room, only the parts needed to be operated under a clean environment use clean rooms. So the factory has several clean rooms. The area behind the clean rooms are called “chase”, and is where the process tools, electricity, exhaust, etc are located.
The floor of the clean rooms and the chases isn’t solid. It uses a mesh for allowing the air to circulate. The air is totally replaced every four minutes. Also, below the fab is where tanks with the chemical products necessary for the manufacturing process are located.
In Figure 4, you can see one of the clean rooms. Pay attention to the floor. Of course inside the clean rooms everybody must wear the so-called “bunny suits” to prevent contamination of the wafers (since the transistors created on the wafer are microscopic even the smallest particle of dust can destroy the chip being manufactured).
On this picture you can a technician handling a black box (called “lot”), which has wafers inside. He is putting the lot inside one machine, or processing tool. Only the “entrance” of the processing tool is located inside the clean room; its body is located in the chase, for cost reductions, as we mentioned.