Study On Carbon Deposition Removal Technology For High-refletion Film Of EUV And X-ray

In recent years,the technology of extreme ultraviolet?EUV?and X-ray source has advanced constantly,and the improvement of performance of the source has brought a severe challenge to the life of optics.Carbon deposition is a common problem faced by EUV and X-ray optical systems.Carbon deposition seriously affects the utilization of light energy and the efficiency of the optical system.The timely and effective deposition of carbon removal technology is of great significance for the development of EUV and X-ray optics.At present,many removal technologies including hydrogen atom,radio frequency hydrogen or oxygen plasma,activated oxygen,were proposed domestic and abroad,but the removal mechanism and process parameter optimization haven't been studied deeply enough.The dissertation focuses on the removal of carbon deposition on high-reflection film Extreme Ultraviolet Lithography?EUVL?and Synchrotron Radiation by radio-frequency argon/hydrogen?Ar/H₂?plasma.This dissertation focuses on the problem of removal of carbon deposition on high-reflection film.For the removal process of radio-frequency Ar/H₂ mixture plasma,the removal mechanism of carbon deposition was theoretically analyzed.The experimental platform for carbon removal was set up,and the removal process research was conducted on the experimental platform.Specific content includes the following aspects:?1?In order to evaluate the effect of the existing carbon pollution removal technology on the high-reflection characteristics,based on the finite difference time domain method,an analysis model of influence of carbon contamination removal technology on EUV multilayer was established.The hydrogen plasma was determined as the main cleaning source of the experimental platform.?2?Based on the physical sputtering analysis equation and surface ion enhanced chemical theory,the carbon removal mechanism on the surface of the optical element by Ar/H₂ mixture plasma was deeply studied.The results showed that argon has enhanced the adsorption of hydrogen atoms in the active gas phase and the desorption effect of the removed product,and chemical material transport was the main aspects of enhanced removal mechanism.A theoretical basis was provided for the experimental study.?3?A series of experimental study was conducted by carbon removal process of Ar/H₂ mixture plasma on optical components.By magnetron sputtering,a carbon layer similar to the actual deposited carbon was coated on the surface of the quartz wafer to monitor the removal rate.Through the theoretical analysis,the main process parameters were obtained,including the pressure,plasma source power and gas mixture ratio.Based on the experimental platform of carbon contamination removal,the research of RF hydrogen plasma removal was carried out.The experimental results show that the highest removal rate can be obtained when the pressure is 0.001mbar,the plasma source power is 99W,and the hydrogen-argon gas mixing ratio is1:2.?4?In order to characterize the argon-hydrogen plasma removal technology on the optical properties of optical components,carbon was deposited on the surface of the EUV multilayer film samples,and a reflectometer and an atomic force microscope was used to test the changes of the reflectivity and the surface roughness before and after the removal process.The experimental results show that the reflectivity and surface roughness of the multi-layer film samples can be recovered and the argon-hydrogen plasma removal technique can be used to solve the carbon deposition problem of the EUV and X-ray optical systems.The dissertation studied the mechanism of the carbon removal technology by RF Ar/H₂ mixture plasma,and the optimal technological parameters of the carbon removal technology were determined through experiments.The influence of removal technology on the optical characteristics of optical components was characterized by using the detection equipments.The research results of this dissertation provided theoretical and technical reference for the removal of carbon deposition in EUV and X-ray optical system,which is of great significance for real-time online removal.