I had this questions come into my head becasue I was watching a video of someone zooming into a microchip and they pass a human hair and continue zooming in an incredible amount. I’ve heard that some of the components in microchips are the size of DNA strands which is mind boggling. I also watched a video of the world’s smoothest object in which they stated that normal objects are no where near as smooth because if you blew them up in size the imperfections would be the size of Mount Everest. Like if you blew a baseball blew up to the size of earth it would have huge valleys and mountains. It wouldn’t be perfectly smooth across. So my question is how are these chip components the size of DNA not affected by these imperfections. Wouldn’t transistors not lay flat on the metal chip? How are they able to make the chips so smooth? No way it’s a machine press that flattens the metal out that smooth right? Or am I talking about two different points and we haven’t gotten that small yet?
In: Engineering
As someone else has said, “photolithography” is like film developing. Semiconductor manufacturing is layers upon layers of masking, exposing, etching, and depositing the next layer of material down, built on top of a slice of a perfect crystal of pure silicon (a wafer). There are hundreds to hundreds of thousands of copies of the same die on each wafer. At the scales required, even specs of dust can create a defect, which is why it is done in clean rooms with people wearing head-to-toe suits; the suits don’t protect the person from the product or process (not primarily), they protect the product from the human. Dozens of layers placed on top of each other extremely precisely; any misalignment, or mistake in processing at any step, will mean some to all of the dies will be bad. You can’t eliminate every potential source of failure, and you can’t just look at it visually, so it is electrically tested before it gets shipped to a customer (does it work like it’s supposed to?). What an “acceptable” amount of loss (how many are thrown away) depends on a large number of factors, but primarily money (how much money you make on each one times how many you sell). If you’re Intel, and your part is complex and worth a lot of money, it makes sense to sort out (“binning”) and sell the ones that aren’t perfect (but usable) for less money. But for simpler parts, it either works 100% or it doesn’t. Even then, the aim is <10% of the parts produced are thrown away, and that’s pretty common for a mature device.
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