What happens inside a fab tool? Tap it, take it apart, and watch it work

From the outside, the tools in a wafer fab are big metal boxes. Playing fab24hr, you keep hearing "ETCH-03 is down again" or "the electrostatic chuck won't hold", but it is hard to picture what those parts look like, or what a wafer goes through inside. This update lets you take the tools apart, and a few of them now move.

How do you open Take it apart?

Tap a tool in the game. At the top of its card is a panel that says Take it apart; tap it and you get a 3D model of that tool:

• After a moment, the tool comes apart by itself, with a number on each part.
• Drag with a finger to turn it; pinch to zoom.
• Tap a number, or start from the first part and tap Next, and each part gets a sentence or two in plain words. Tap any term you don't know for a short explanation.
• Slide the bar back to Together and the parts fly back into place.

The production fab, the R&D line, the subfab and the test-and-assembly house all have tools you can take apart: etch, film deposition, litho, furnaces, cleaning, polishing, ion implantation, measurement, the vacuum pumps and exhaust treatment, and at the test-and-assembly house, probing, dicing and wire bonding.

What does See it work show?

A few tools have an extra button, See it work. Tap it and the tool puts itself back together, then runs step by step: a line at the top says what is happening, the parts that are moving light up, and the camera moves in. After one round it starts again; tap Stop to go back to how it was. If your phone or computer is set to reduce motion, you tap Next for each step instead.

Plasma etch chamber: digging trenches with plasma

The wafer comes in through a valve in the side. Lift pins rise to catch it and lower it onto the electrostatic chuck, which holds it flat. The chamber is pumped down to a vacuum and the etch gas flows in; a coil on top is fed high-frequency power, and the gas turns into a glowing plasma. Finally the electrode underneath pulls ions out of the plasma, straight down onto the wafer, digging trenches that are deep and straight.

One trip through litho: printing the circuit onto the wafer

It starts at the coater/developer: a puddle of photoresist lands in the middle of the wafer, the chuck spins fast and flings it into a thin, even layer, and a hot plate dries it. Then the wafer goes to the scanner, which first measures the alignment marks and the height across the whole wafer. The laser flashes, the photomask and the wafer sweep in opposite directions, and the shrunken circuit pattern is printed one field at a time. Back at the coater/developer, the wafer is baked again and covered with developer; the resist that was hit by light dissolves and the circuit pattern appears (develop). The trip switches between the two tools by itself.

Chemical mechanical polishing: grinding the wafer flat

In chemical mechanical polishing, the wafer is polished upside down: a polishing head holds it by vacuum and presses it onto the polishing pad. Slurry drips onto the pad, and the disc and the head both turn, grinding the surface flat. Beside them, a conditioner sweeps back and forth across the pad, and a small window in the disc watches the wafer from below and stops when it is done (endpoint detection). There are three discs, each finer than the last; afterwards the wafer is cleaned and spun dry, and only a dry wafer leaves the tool.

Cluster tool: how one wafer gets in and out

Many tools have more than one process chamber, arranged around a transfer chamber in the middle. A robot arm takes one wafer from the wafer pod, turns it once to find the notch on its edge, and puts it in a load lock that is pumped down to a vacuum; a second robot inside the vacuum then carries it to the chamber it needs, and it comes back the same way. Open the etch chamber or a film chamber and you will find it under See also.

Why build this?

The stories in the game keep mentioning tool parts: an electrostatic chuck that won't hold, a polishing pad that is worn out, a scanner waiting on its coater/developer. Until now you could only imagine them; now you can open the tool and see where each part is and what it does. You don't need to know anything about semiconductors first: once you have seen what a wafer goes through inside, the stories make more sense.

In fab24hr

fab24hr is a free browser game that needs no install: you work one shift as an engineer in a wafer fab. The tool models are drawn the generic, textbook way, with simplified shapes, proportions and details, and are not modelled on any company's machines; the order of the steps follows public textbooks and course notes. The companies, people and events in the game are all fictional. If something looks different from the real thing, tap the bug icon at the top of the screen or use Wishes and problem reports.