(Extreme Ultra Violet lithography) Also known as EUV lithography is a next-generation lithography using the 13.5 nm wavelength. EUV is a significant departure from the deep ultraviolet (DUV) lithography used today. EUV lithography takes place in a vacuum as all matter absorbs EUV radiation. All the optical elements, including the photomask, must make use of defect-free Mo/Si multilayer which reflects light by means of interlayer interference; any one of these mirrors will absorb around 30% of the incident light. EUV source development has focused on plasmas generated by laser (LPP) or discharge (DPP) pulses. The mirror responsible for collecting the light is directly exposed to the plasma and is therefore vulnerable to damage from the high-energy ions and other debris.