How do they make the transistors for processors so small?

Question

I know there is no possible way they are made by hand or mechanical means. what do they do?

Answer 1

In short, a process called "photolithography", a kind of photgraphic process that works sort of like a photo enlarger, but in reverse: a large image is projected onto a smaller size.

ICs are made up in layers, or "masks" that are projected onto the wafer and processed, one at a time, to build up the structure of the IC. A simple IC might have half a dozen layers, a complex one more than 30.

For larger geometry, a mask (reticle) covers an entire wafer at once. Finer geometries use a reticle that is projected onto the wafer at a smaller size (optically shrunk) and stepped to cover the whole wafer.

The technology for maskmaking and exposure is deep topic, on the cutting edge of physics. Linkage below...

Answer 2

They use masks and chemical etching.

simplified, a material (resist) is used to coat the silicon. Then a UV light is shone through a mask and focused on the silicon wafer, which causes a chemical change in the resist. Then a chemical wash washes away the part of the resist that was exposed to the UV (or the other part, I forget). This leaves a pattern of resist on the surface. Now one of several things can happen. Either silicon vapor is used to plate more silicon on the bare area, or acid is used to etch away the bare silicon, or metal for interconnects is deposited on the bare spots.

This is repeated many times with different masks, building up the structure layer by layer, until it is all done, and attached to the package and sealed.

.