Anatomy of a fab
From outside, a chip fab is a windowless box the length of several football pitches. Inside, it is the cleanest, stillest and most tightly controlled room people have ever built.
A building in six layers.
Chips are made on one floor. The five layers around it keep that floor clean, still, cool and supplied. Pull the building apart, then pick a layer.
The production floor: tools in rows, with the overhead rail above them.
Air that falls like rain.
The whole ceiling pushes filtered air straight down, at about 0.45 m/s, the speed US Federal Standard 209 recommended for rooms like this. It sweeps past the tools, through the perforated floor, up the side shafts and back through the filters. Anything a person or a tool sheds is carried down and away from the wafers.
Red specks are particles picked up in the room. They stay red until the filters in the ceiling catch them.
Under ISO 14644-1, class N allows at most 10N particles of 0.1 µm and larger per cubic metre. Each step on the slider is ten times dirtier. Lithography bays typically hold 23 ± 0.1 °C, and fabs keep relative humidity near 45% ± 2%, tighter around lithography, according to the fab engineers CKY. A wafer that warms by a fraction of a degree grows by nanometres.
A railway on the ceiling.
Wafers travel in sealed plastic boxes called FOUPs, 25 at a time. A loaded FOUP weighs 7 to 9 kg, too heavy to carry safely all day, and too valuable to risk. So no one carries them.
Overhead hoist vehicles run on a monorail above the tools. Each one stops over a tool's load port, lowers the FOUP on belts, and leaves. In a large fab, Daifuku's systems run about 10 km of track and 1,000 vehicles, at up to 200 m per minute.
Inside the FOUP the wafers sit in their own micro-environment, often purged with nitrogen. The box, not the room, is the cleanest place a wafer spends its life.
Round and round, a thousand times.
A car factory is a line: parts enter one end and leave the other. A fab is a loop. The same lot comes back to lithography, etch, deposition and cleaning again and again, once for every layer of the chip.
Leading-edge logic runs to 80–100 mask layers and up to a thousand steps. Most of the time is not processing but waiting: a wafer spends about one minute under the scanner, then queues for the next tool.
An illustrative lot: five tools, one pass per layer, speeding up as it goes. Real routes visit many more tool types.
The machine under the machine.
What you see of a tool in the cleanroom is its clean end. Its pumps, gas supply, chemical feed and exhaust treatment sit one level down, in the subfab, plumbed up through the floor.
Every tool upstairs is plumbed to kit downstairs. The cleanroom floor stays open and clean because the heavy, hot and dangerous parts live one level down.
Stillness is a utility.
A scanner places each layer on the one below to within a few nanometres. A footstep, a passing cart or a pump down the hall can shake that away. So fabs are built on thick waffle slabs and stiff columns, and the most sensitive tools stand on pads cut free from the floor around them.
Fab floors are specified against vibration criteria such as VC-D and VC-E: floor velocities of 6.25 and 3.12 µm per second. You would not feel either.
Cleanrooms, stacked.
Classic fabs have one cleanroom level over one subfab. The newest memory fabs stack them. SK hynix says the first fab of its Yongin cluster has two building shells holding six cleanrooms, in a building as tall as a 50-storey apartment block, with the first cleanroom opening in February 2027.
BusinessKorea reported in August 2026 that Samsung plans the same at Pyeongtaek P5: three fab floors instead of two, and up to six cleanrooms per building instead of four. The plan still needed sign-off from Gyeonggi Province and the national land ministry.
Why stack? More cleanroom on the same plot of land, next to the same utilities. The price: lifts to move FOUPs between levels, and a taller structure that must still hold the stillest floors in industry.
One building, every step.
Everything the other explainers describe happens inside a building like this one: the scanner that prints each layer, the plasma that cuts it, the films that fill it.
Press Explore at any point on this page to turn the model and look inside it. Snapshot keeps the view you framed as a picture.