Figure  Wavelengths relative to the lengths of familiar objects Conventional ArF lasers are classified as DUV (Deep UV), and have a wavelength of 193nm. In contrast, the wavelength of EUV is just 13.5nm - smaller than the size of a molecule.
The shift from 193nm ArF to 13.5nm EUV therefore signifies a giant leap. Now let’s take a closer look at the photolithography process made possible by EUV.
A. Short wavelengths created by energetic plasma
Figure  above shows the rainbow-colored light spectrum we are all familiar with. As we move toward shorter wavelengths, we get ultraviolet rays, responsible for giving us sunburn, then x-rays, which can pass straight through our muscles, and then gamma rays, which are powerful enough to destroy cancer cells. In other words, the shorter the wavelength of light, the stronger its energy. As short-wavelength light has high energy levels, creating light with shorter wavelengths requires larger amounts of energy. It’s similar to baseball. If you want to send the ball farther and faster, then you need to swing the bat harder. But the lasers used to create conventional DUV light had energy levels insufficient for creating the short wavelengths we needed. This is why EUV, as shown in Figure , uses plasma (the fourth state of matter, following solids, liquids and gases: in highly energetic plasma, the atoms of matter are separated into electrons and ions).