EUV light is generated by the deposition of laser or electrical energy into a source element, such as xenon (Xe), tin (Sn), or lithium (Li), creating ionized gas microplasma at electron temperatures of several tens of electron volts. As these highly excited ions decay, energetic radiation is emitted in all directions. For EUV lithography, the 13.5 nm radiation is collected by a mirror (either grazing incidence or normal incidence) and focused to an intermediate point where it is relayed to the scanner optics and, ultimately, the wafer.

LPP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Laser Produced Plasma (LPP) and Discharge Produced Plasma (DPP) are the leading technologies for generating high power EUV radiation at 13.5 nm. In both technologies, hot plasma is generated with produces EUV radiation. In LPP, the target material is heated by a laser pulse to generate high-temperature plasma. In DPP, magnetic pinching of low-temperature plasma generates the high-temperature plasma.

DPP. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Cymer historically investigated DPP EUV source technology using Xe as the source material due to its simplicity and overall electrical efficiency. Due to the configuration, DPP sources face extreme electrode heat-extraction challenges. Over the years, the company focused on improving electrode thermal extraction from smaller electrodes, and in 2004, the company demonstrated the ability to extract more than 20kW from source electrodes. Such operational power levels, however, are below those required to reach high volume manufacturing source powers. These levels are also at the extreme limits of what can be accomplished with known material and cooling techniques.

• Power Scalability
  The high conversion efficiency of the CO₂ laser wavelength at 10.6µm and Sn combination allows for power output at the levels required by the lithography system.
• Isolated Plasma
  By maintaining long distances between the hot plasma and the chamber components, component lifetime is extended. Also, since there are no electrodes, no electrode cooling is required and no electrode debris exists to damage the collector optics.
• Small Etendue (property of light that characterizes how ‘spread out’ the light is in area and angle.) The LPP approach creates a much brighter plasma with a small etendue. This enables the collection of more light - meaning more efficient collection. This significantly reduces the complexity of optical systems designs in the scanner. 
• Mass-Limited Operation
  Small droplet production leads to less generation of debris. Reduction of fuel consumption and COO. 
• Normal Incidence Collector
  The MLM coating has spectral filtering properties, and the collector substrate has greater thermal load capacity
• High Repetition Rate
  Translates to better dose control of the resulting EUV light.