The building as a machine
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.
This page takes the building apart floor by floor, then follows one box of wafers through it. Scroll to go on. Drag a scene to turn it.
Step and day counts are for leading-edge logic, as reported by Semiconductor Engineering. Memory and older nodes need fewer.
01 Cross-section
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.
02 Airflow
Air that falls like rain.
The whole ceiling pushes filtered air straight down, at about 0.45 m/s. 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 also hold 23 ± 0.1 °C and about 45% ± 2% relative humidity, because a wafer that warms by a fraction of a degree grows by nanometres.
03 Automated material handling
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.
04 The route
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.
Pick an area to see what it does. The route here is illustrative, and days are scaled so a thousand steps take about a hundred days.
05 The level below
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.
06 Vibration
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.
07 The new shape
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.
Samsung is reported to be planning the same at Pyeongtaek P5: from two storeys to three, and from four cleanrooms to six. That plan still needs government approval.
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.
08 Where to go next
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.
- Writing with light: how a lithography scanner prints a layer
- Sculpting in atoms: etch and deposition
- The impossible machine: why a scanner is fast and exact at once
- The fab map: where the world's fabs are
- Chips on chips: HBM and advanced packaging
- Wrapping the gate: how the transistor went 3D
Every figure comes from a publisher named below. The buildings shown are generic, not any company's design. Figures are rounded.