They aren't built at the same scale, they're much larger than the final structure and lenses are used to scale the image down to the desired size.

Here's a video form Intel on how they are made: https://youtu.be/u3ws0UebnSE

Apparently they use "electron beams", not sure what those are, they sound similar to lasers but with electrons, from this video: https://youtu.be/PWV9pvdRBNY