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Part 1 · Welcome to the semiconductor world
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A semiconductor's world is too small to see, and that is the whole point.

Hold a ruler against everything you know and the numbers run out fast. A human hair is about seventy micrometres across — already the finest thing your eye can resolve. A red blood cell is ten times finer. Green light itself is ten times finer again. And a modern transistor is built from features smaller than the wavelength of the light we once used to draw them. Shrinking is not a bragging right. It is the only reason a chip can hold a city.

  1. The last visible thing

    A hair is about 70 micrometres thick. Everything to its right is invisible to your eye, whatever the lighting.

  2. Two silicon atoms

    Neighbouring silicon atoms sit about 0.24 nanometres apart. That is the floor — you cannot build half an atom.

  3. About those node names

    Nothing on a “3 nm” chip measures 3 nm. It is the name of a process generation, not a measurement.

Ten decades of smallness, on one ruler.
  1. 1The last visible thingA hair is about 70 micrometres thick. Everything to its right is invisible to your eye, whatever the lighting.
  2. 2Two silicon atomsNeighbouring silicon atoms sit about 0.24 nanometres apart. That is the floor — you cannot build half an atom.
  3. 3About those node namesNothing on a “3 nm” chip measures 3 nm. It is the name of a process generation, not a measurement.
10^{10}
the span of this one ruler, from a person to an atom

Ten factors of ten. Each step to the right divides by ten again.

An optical microscope

Stops at about 200 nanometres. The physics of visible light will not let it see finer.

An electron microscope

Uses electrons instead of light, and can resolve single atoms. This is how engineers look at their own work.

Smaller is not a bragging right. It is the only way to fit a city onto a fingernail.