The air in the cleanroom is the purest you’ve ever breathed. It’s class 10 purity, meaning that for every cubic foot of air there can be no more than 10 particles larger than half a micron, which is about the size of a small bacteria. In an exceptionally clean hospital OR, there can be as many as 10,000 bacteria-size particles without creating any special risk of infection. In the outside world, there are about 3 million.
The cleanroom is nearly silent except for the low hum of the “tools,” as Intel calls them, which look like giant copy machines and cost as much as $50 million each. They sit on steel pedestals that are attached to the building’s frame, so that no vibrations—from other tools, for instance, or from your footfalls—will affect the chips. You step softly even so. Some of these tools are so precise they can be controlled to within half a nanometer, the width of two silicon atoms.
It’s surprisingly dark, too. For decades, Intel’s cleanrooms have been lit like darkrooms, bathed in a deep, low yellow.