Studies On Plume Expansion And Radiation Spectra Of Pulse Laser Produced Tin Plasma

With the decreasing size of semiconductor technology requirements, 13.5 nm of EUV light source has become the next generation lithography light source and been highly anticipated. By the use of the EUV light source, the semiconductor node is expected to be shortened to 10 nm and the node 7 nm, theoretically, 10 ns node is reached even without the use of double patterning(DP) technology. However, two key problems, which are low particle debris and high EUV conversion efficiency, have to be solved before the EUV light can be used in industry.The study on the physical properties of plasma is important to improve the EUV conversion efficiency and reduce particle debris production by pulsed laser produced tin plasmas. In this thesis, the properties of the plasma from two aspects that the plasma plume and radiation spectrum were investigated, the main work and results are as follows:(1)Using Nd:YAG pulsed laser as the generating EUV light source and tin as the generating target, the two-dimension(2D) pictures of Sn plume from the Nd:YAG pulsed laser induced tin target were taken directly by ICCD directly. From the plasma plume, the boundary particle kinetic energy, collision cross sections and mitigation efficiency have been researched in different experimental conditions such as different laser energy, different buffer gas and different pressures.(2)Using spectrometry to measure and record the plasma emission spectroscopy by Nd: YAG laser-induced tin target, the electron temperature and electron density of plasma in different laser energy and different pressures were calculated by Boltzmann mapping and Stark broadening.(3)In order to study the effect of different laser for EUV Plasma plume expansion characteristics, CO2 and Nd:YAG pulsed laser was used to produced tin plasmas for developing an extreme-ultraviolet(EUV) lithography light source respectively. using the plasma plume we studied the changes of the kinetic energy of plasma particles, slowing efficiency and the collision cross section under the same conditions of laser energy density. And the changes in plasma electron temperature and electron density was researched by radiation spectrum under the same laser energy.