Although a photolithographic process is used to print the circuit patterns on the chip, this process is millions of times more precise than the process
used by the printing industry. This and other operations are performed by computer-controlled robotic devices in "clean rooms" that are a thousand times cleaner than a hospital operating room. No human
hand is ever allowed to touch a wafer. Workers are garbed in "bunny suits" that cover them from head to toe. The air is continuously filtered and recirculated to keep the dust level at an absolute minimum.
Temperature, barometric pressure, and humidity are controlled to unheard of tolerances in order
to protect microscopic circuits that, in some advanced IBM technologies, measure slightly more than a polio virus. In fact, a single particle of smoke, if it were allowed to infiltrate a semiconductor "white
room," could destroy an entire chip.
