How Photolithography Works

The ultimate limit on the feature size photolithography can produce is set by the wavelength of the light it uses and the physics of electromagnetism, but clever device designers have invented a bag of dirty tricks to squeeze more onto a chip. The series concludes with a survey of some of these techniques, including multiple exposure and etching cycles, atomically deposited spacers, self-assembling molecules, and three-dimension stacking of transistors.