Silicon chips are all about layering – layering silicon, glass and metal together in just the right way to make the “circuit” you need.
You need advanced chemicals, precision, temperature control and lots of other tricky stuff to get those materials to line up exactly how you want.
DESIGNING the layers is tricky, but so is MAKING those layers. Very clever people found a way to layer together silicon, glass and metal to make flat little electrical switches (called MOSFETs). The design part of it is almost like asking “how hard is it to make software or develop a new drug;” if you know how to layer those materials together to get the “circuit” you want, then the design part is done. In fact, you could make a silicon chip that just acts as a light switch if you wanted.
Making it is a different animal and quite fascinating – a raw crystal is slowly drawn out of molten silicon, cooled and then sliced into thin round disks (wafers). Then, the layers are added into the wafers – patterns of glass and metal are layered on top and the silicon layer is “treated” in certain spots to give it different properties. The end result is a tiny, flat switch made possible by just the right layering of metal, silicon and glass.
The Computer History Museum in Mountain View, CA has an outstanding exhibit on this. You can see an exhibit showing some of the first MOSFETs, planar ICs, etc. There is also a cool plaque at a restaurant called Buck’s in Woodside, CA that explains it and shows a wafer.
It’s very difficult, because you have to very precisely determine, which atom is where. You have very small regions where there cannot be a certain type of atom and others where they must be, but not another type. So silicone itself needs to be very pure and then be made impure at very precise locations.
great answers but as far as I can see the part about designing the chip – meaning to figure out what transistors to put on the sillicon chip to make it do the intended task. A big group of ppl has to spend a lot of time to figure that out. Which for big chips cost many many millions of dollars in salary, many complicated and specialized software and 12-15 months of time or more. And if there is a mistake in the design(happens on every design), have to go through the whole process again.
Also I posted this as reply to one of the first answers to original post, which had a great breakdown of the process but somehow the answer (not mine) was removed by moderators
Simple stuff can be done by a single individual. See this guy who fabricates simple structures in his garage: https://www.youtube.com/watch?v=IS5ycm7VfXg
The difficulty just ramps up as you shrink the feature size and start making more complicated designs. In the old days, you’d physically “tape out” the design on basically projector slides. These days you use CAD, etc.
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