I was watching the new 4nm transistor size for the new Qualcomm snapdragon 8 gen 2. How does the parts of processors get so small that they’re the same size as around a few dozen atoms?
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They don’t build transistors in a CPU one at a time.
Instead they make a plate that makes a big shadow of the desired circuit, then use lenses and mirrors to shrink the shadow.
Aim the shadow at a very flat layer of light-sensitive chemical, and the non-shadow parts are weakened. So when you wash it with acid, only the light-exposed parts are washed away. With a plate that makes an extremely intricate shadow, you can make extremely intricate structures all at once.
That’s the basic idea of how millions (or even billions) of transistors, wires and other structures can be made small and cheap enough for a CPU that only costs hundreds of dollars and fits comfortably in your hand.
The components aren’t built individually, instead there’s a series of large scale “passes” of lens-shrunken light / shadow patterns and various chemical treatments. The entire structure is created at once as a single piece, including all the millions / billions of components in specific positions and the connections between them.
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