The Design And Analysis Of The Atomic Hydrogen Source

Extreme Ultraviolet Lithography is the most promising next-generation lithography, while the clean technology of contamination of optical surface is one of the key technologies to be solved. The technology of using atomic hydrogen to conduct online cleaning at low temperature, is considered to be one of the effective techniques. In this thesis, the key equipment-- atomic hydrogen source which is used to clean optics contamination is studied. The main work and results are as follows:The technical scheme of atomic hydrogen sources is proposed. First, tungsten filament is heated through high-temperature thermal radiation. Then hydrogen stream is warmed up tungsten filament. At last, hydrogen-molecules are cracked into hydrogen-atoms. The temperature of tungsten filament can be controlled accurately through current regulation and temperature feedback. The heat affection on external components is reduced by using molybdenum insulation and water-cooling structure to shield the thermal transmission of high-temperature tungsten filament. The scheme has the advantage of high pyrolysis rate, controllable flow of hydrogen atom, and cleaning effect of optical surface contamination.The relationship between pyrolysis rate of Hydrogen and the temperature of tungsten tube, as well as the hydrogen flow is studied. The pyrolysis rate increases with the increasing of tungsten filament temperature, and decreases with the increasing of the hydrogen flow. The pyrolysis rate achieves 90% when the temperature of tungsten reaches 2115 k. The increasing rate of pyrolysis rate begins to decrease as the tube temperature continues to rise. The hydrogen flow can be determined based on the total demand of hydrogen pyrolysis rate and density of hydrogen atoms. Right after, the analytic expression between temperature and heating current is established.The detailed structure of atomic hydrogen source is designed. To avoid the impact caused by the softening phenomenon of tungsten filament through adopting helical structure, matching the relationship between pitch and diameter of tungsten filament, choosing reasonable materials and installation method. The heat effect on external components is reduced by using molybdenum insulation and the water cooling structure to shield thermal transmission of high-temperature tungsten filament. The foundation of integration and application of atomic hydrogen source is laid through adoption of the lightweight and compact design. The device has been assembled and is under performance debugging.The testing method of atomic hydrogen source is proposed. The pyrolysis rate is calculated through measuring the number of hydrogen atoms and the flow of hydrogen by using residual gas analyzer. Meanwhile, the performance test device of atomic hydrogen source is designed and built, having the ability to test the performance of atomic hydrogen source.