How do they make the "chips" in computers?

This is done using an optical process, not unlike how old photos were printed. A silicon wafer is covered with some etching resisting material, and then exposed to UV light through a mask. The mask is a drawing of the chip schematic.

The etching resisting material is removed where the light hits (or vice versa), and parts of the silicon wafer is etched away with a chemical. Different layers can be deposited by repeating this process.

Finally the wafer is cut into little rectangles and placed inside a housing.

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