Ask HN: How do you actually layer a chip?

2 pointssnr2 comments

All the fab videos I could find on the internet talk about taking a single sheet of silicon, performing lithography and connecting components with copper wires. I don't see how they build 10-30 layered chips. Is it that they layout all the layers on a single sheet and form virtual layers by copper wire interconnects?

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As I understand it, they deposit a layer of oxide on the first layer, pattern it, and preferentially etch in order to allow selective interconnection to the existing layer, then deposit fresh layers of silicon on top to do it all over again.

Chemical vapor deposition or sputtering is how they do deposition. Put wafer in vacuum chamber, suck out all gas, then make the desired compound form by zapping targets or cooking exotic gases like silane.

Sometimes, as with top-end solar cells, they'll even change the material from layer to layer.

I thought CVD is used for laying out interconnects, no? It's used for laying out silicon?

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