In this video, the letters that spell Molecular Foundry were written with a beam of electrons fired at the surface. The smallest feature is 20 nanometres, or approximately 100 atoms.
As the video zooms out, you lose sight of Molecular Foundry and see the Berkeley Lab logo, which was written with a beam of charged gallium atoms. As you continue to zoom out, you see an 18 hour time-lapse of Abraham Lincoln’s face, again written with gallium atoms. Finally, all of this is done within the Lincoln Memorial side of the penny as it is removed from the focused ion beam.
Photolithography, which literally means writing with light, is the foundation for most top-down fabrication of things like microprocessors. However, because of something called the diffraction limit, photolithography is limited to devices that have features no smaller than the wavelength of the light used, often in the 100s of nanometers. As a result, things smaller than light like atoms and electrons must be used.