| Compared with traditional polishing methods, the plasma polishing technology has advantage of processing effect, and has been widely applied in the field of microelectronics and optical manufacturing. According to the current specific practical problems in the optical element, vacuum plasma technology is applied to the manufacturing of Ultra-smooth Surface. It can rapidly remove the cutter mark of the formation in precision CNC grinding process and remove effectively the surface defects and sub-surface damage of the optical material, and reduce the optical losses of optical element by the plasma active radicals and ions of the chemical reaction.Based on the existing polishing experiment facility, capacitive coupled plasma source of RF discharge method was designed. The plasma source could realize discharge. Langmuir probe was applied to diagnose plasma characteristics. The influence of processing parameters (RF power, working pressure, the gas flow rate of the Argon, the gas flow rate of the Oxygen and the gas flow rate of the CF4) on surface roughness and etching rate were studied by the technology of capacitive coupled plasma and inductively coupled plasma. Finally, the chemical removal mechanism of the vacuum plasma on the surface of quartz is preliminarily discussed.The research suggests that the optimal parameters in the ICP-98A process experiment are RF power of 180W, Argon flow rate of 70sccm, Oxygen flow rate of 10sccm, CF4 flow rate of 30 sccm and working pressure of 2Pa and etching time of one hour on quartz surface. By RF bias, surface roughness of quartz is improved and reduced to 1.19nm on these parameters. Also, maximum etching rate of 153.33nm/h has been recorded. Compared with the physical sputtering plasma etch rates is obviously improved. The profile accuracy of quartz surface is improved by 0.32λ to 0.08λ by plasma etching. By IBE-3000S ion manual etching machine of RF ion source, the distance at 80mm, RF power of 250W, working pressure of 5×10-2Pa, Argon flow rate of 10 sccm, beam voltage of 1200V are the optimal process parameters. The results show that the maximum fixed-point etching rate of quartz about 478.7nm/min and the etching spot diameter about 13mm. The results show that the fixed-point etching rate of the focusing structure more than the parallel structure etching rate, but etching efficiency will be much smaller by automatic control system of large aperture processing with multi axis motion. Finally, the effects of RF power and argon flow rate on the PC3-1500 photoresist film are studied. The results of the experiment show that photoresist film can be rapidly removed and surface roughness will not be affected.The capacitive coupled plasma source (CCP) was designed and worked stably, with good reproducibility in this article. It can achieve stable discharge with bright glow. The results of the Langmuir probe experiment investigated that the electron temperature and electron density of Argon plasma increased with the increase of RF power. Good uniformity of Argon plasma is ±4% in diameter of 20mm. Research on CCP etching experiments suggests that the optimal parameters are RF Power of 80W, Argon flow rate of 20sccm, Oxygen flow rate of 20sccm, CF4 flow rate of 40sccm and working pressure of 50Pa. The high etching rate of 1.93nm/min was obtained and surface roughness was reduced from 2.35nm to 1.37nm after etching. Surface roughness of quartz is improved and reduced to 1.18nm. The profile accuracy of quartz surface is improved by 0.25λ. to 0.1λ by plasma etching. Finally, the CCP was applied in the treatment of PC3-1500 photoresist film. The surface roughness is better than 0.91nm. The effect is better than ICP, but the etching rate is less than ICP. |
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