It seems somewhat like a chicken/egg situation. How exactly were we able to create such precise processors when we only could have had more primitive tools to craft them with? For instance, take the UV stencil used on a silicon wafer to make a CPU.

How could engineers have designed a machine capable of cutting out so many millions of transistors in the stencil before they invented a computer capable of registering so many digits of detail in this new stencil in the first place? Because if they already had a machine that useful and precise, then why would they have needed to make a newer version? It would be like using a steel knife to carve a wooden knife.