Sources of ultraviolet light based on microwave discharges

Today microand nanoelectronics industry requires a source of extreme ultra-violet (EUV) radiation with a wavelength of 13.5 ± 1 % nm for high resolution projection lithography. The size of the emitting region must be less than 1 mm. One of the most promising sources of EUV light is considered to be a source that uses a pulsed CO2 laser radiation focused on a specially formed stream of droplets of tin with dimensions of the order of 0.1 mm. However, along with tangible achievements in these light sources have a number of fundamental flaws that do not allow us to consider the problem of creating a EUV light source to be solved. We propose a source of EUV radiation based on plasma heated by microwave radiation. The nonequilibrium ECR plasma is an effective source of radiation in the EUV region. Radiation of the plasma can lie in the region of 100 angstroms. This range contains the line radiation of multiply charged ions excited by electron impact. The EUV line emission from a pulsed electroncyclotron resonance discharge in argon, maintained by a high-power millimeter-wavelength beam in a magnetic mirror trap, was studied using a multilayer mirror EUV monochromator. The EUV spectrum was measured, and the absolute spectral intensity of emission was determined in a 6–17 nm wavelength range. The discharge can be used as an effective source of EUV light with an efficiency of the microwave to EUV light power conversion on a level of 10% and a maximum spectral power density of 7.3 kW/nm at a wavelength of 9 nm. Plasma was created and sustained by the microwave radiation with frequency of 37.5 GHz and power of about 100 kW. Scheme of the experiment shown in Fig. 1 [1].