How are computer chips actually manufactured? Start from sand and take me all the way to the chip in my phone.
A chip is a few billion to a couple of hundred billion tiny switches (transistors), wired together, on a sliver of purified silicon. Making one takes about three months, a factory that costs tens of billions of dollars, and a few machines that only one company in the world builds. Here is the whole path, then we can zoom in.
1. Sand to silicon. Beach sand is mostly silicon dioxide. It is heated with carbon to get raw silicon, then chemically purified until it is better than 99.9999999% pure ("nine nines"). Almost every impurity atom is a defect, so this is purer than almost anything else humans make.
2. Silicon to a single crystal. The purified silicon is melted (it melts at about 1,414 °C). A small seed crystal is dipped in and pulled up slowly while rotating, and the silicon freezes onto it as one perfect crystal, an ingot up to a couple of metres long. This is called the Czochralski process.
3. Ingot to wafers. The ingot is sliced into discs under a millimetre thick, then polished until they are flatter than a mirror. The standard size is 300 mm across. One wafer will carry hundreds of identical chips.
4. Wafer to circuits (the fab). This is the long part, inside a cleanroom thousands of times cleaner than a hospital operating theatre, because one dust particle can kill a chip. A wafer goes through the same few kinds of operations, over and over, building the transistors first and then the copper wiring above them. Typically that is about three months for an advanced chip and well over a thousand individual process steps.
5. Test, cut, package. Each chip is tested on the wafer, the wafer is cut into individual chips (dies), good dies are put in a package that connects them to the outside world, and they are tested again.
6. Assembly. The packaged chip goes onto a board in a phone, a laptop or a server.
The interesting part is step 4, because it is not a single recipe. It is one small loop repeated dozens of times. That is what to unpack next.
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