Plasma Enhanced Chemical Kaleidoscope
The color of a thin film is dependent on thickness, similar to when you have a small amount of oil floating on water. When researchers randomly cover parts of a wafer while depositing material, the result is a rich pattern of colors due to variations in the film thickness after many uses.
Plasma enhanced chemical vapor deposition is a technique to deposit thin films ranging from 10s of nanometers to 1000s of nanometers. When a carrier wafer is used, smaller pieces are randomly oriented on the surface causing unequal deposition. Over time the random placement leads to a rich color variation over the surface of the carrier wafer. The image was taken with an off axis iPhone with a S/Pec-Wipe 3 backdrop to prevent background object reflections from appearing the wafer surface.