Experimental investigations of silicon tetrafluoride decomposition in ECR discharge plasma

The results of first experiments on the investigation of plasma of electron cyclotron resonance (ECR) discharge, sustained by CW radiation of technological gyrotron with frequency 24 GHz are considered. The parameters of nitrogen plasma of ECR discharge in magnetic field up to 1 T were investigated by Langmuir probe in the pressure range 10-4-10-2 mbar under different values of microwave power. Depending on gas pressure and power of microwave radiation, the typical temperature and density of electrons could attain values of 1-5 eV and 1011-1012 cm-3, respectively. The prospects for using of ECR discharge for plasma chemical decomposition of silicon tetrafluoride (SiF4) have been experimentally demonstrated. Plasma was created from SiF4 and hydrogen (H2) gas mixture and heated by microwave radiation in ECR conditions. Using the method of mass-spectrometry analysis of the gas at the outlet from the reactor and the weighting method, the content of the resultants of SiF4 decomposition as a function of process parameters was investigated. It was shown that SiF4 decomposition degree strongly depends on the microwave power, gas pressure in the reactor, gas flow rates, and can attain the value of 50%. The possible applications of PECVD method based on ECR discharge for production of isotopically pure elements with high deposition rate are discussed.