A modern TSMC fab is the most controlled environment humans have ever built for manufacturing, and almost nothing inside it is touched by a human hand. The air alone is the giveaway. A leading-edge cleanroom runs at ISO Class 1 to 3, meaning fewer than a handful of particles larger than 100 nanometers per cubic meter of air. Your living room has tens of millions. The fab achieves this by pushing filtered air down from the ceiling through ULPA filters in a continuous laminar sheet, flushing the entire room volume hundreds of times per hour so any stray particle is swept to the floor grating before it can land on a wafer. The reason for the paranoia is scale. Features on a 3nm node are smaller than the wavelength of visible light. A single dust speck landing in the wrong place kills the die. So the wafers travel sealed. That is where the steel highway comes in. Look up in any fab and you see a lattice of overhead rails running near the ceiling. This is the Overhead Hoist Transport syst...