CF₄ molecular gas is used in most of semiconductor manufacture processing and SF/sub 6/ molecular gas is widely used in industrial of insulation field. but both of gases have defect in global warming. C₃F/sub 8/ gas has large attachment cross-section more than these gases, moreover GWP, life-time and price of C₃F/sub 8/ gas is lower than them, therefor it is important to calculate transport coefficients of C₃F/sub 8/ gas like electron drift velocity, ionization coefficient, attachment coefficient, effective ionization coefficient and critical E/N. The aim of this study is to get these transport coefficients for imformation of the insulation strength and efficiency of etching process. In this paper, we calculated the electron drift velocity (W) in pure C₃F/sub 8/ molecular gas over the range of E/N=0.1∼250 Td at the temperature was 300 K and gas pressure was 1 Torr by the Boltzmann equation method. The results of this paper can be important data to present characteristic of gas for plasma etching and insulation, specially critical E/N is a data to evaluate insulation strength of a gas.
This paper describes the information for quantitative simulation of weakly ionized plasma. In previous paper, we calculated the electron transport coefficients by using two-term approximation of Boltzmann equation. But there is difference between the result of the two-term approximation of the Boltzmann equation and experiments in pure CF$_4$ molecular gas and in CF$_4$+Ar gas mixture. Therefore, In this paper, we calculated the electron drift velocity (W) in pure CF$_4$ molecular gas and CF$_4$+Ar gas mixture (1 %, 5 %, 10 %) for range of E/N values from 0.17～300 Td at the temperature was 300 K and pressure was 1 Torr by multi-term approximation of the Boltzmann equation by Robson and Ness. The results of two-term and multi-term approximation of the Boltzmann equation have been compared with each other for a range of E/N.
This paper describes the information for quantitative simulation of weakly ionized plasma. We must grasp the meaning of the plasma state condition to tilize engineering application and to understand materials of plasma state. The electron transport characteristic in has been analyzed over the E/N range of 0.1~300(Td) at the 300(K) by the two term approximation Boltzmann equation method and Monte Carlo Simulation. A set of electron collision cross section has been assembled and used in Monte Carlo simulation to predict values of swarm parameters. Boltzmann equation method has also been used to predict swarm parameter using the same cross sections as input. The behavior of electron has been calculated to give swarm parameters for the electron drift velocity(W), diffusion coefficients(D), the ratio of diffusion and mobility(D/), mean energy(. The electron energy distribution function has been analyzed in at E/N=10 and 100 for a case of the equilibrium region in the mean energy. The results of Boltzman equation and Monte Carlo Simulation have been compared with experimental data by Ohmori, Lucas and Carter. The swarm parameters from the swarm study are expected to sever as a critical test of current theories of low energy scattering by atoms and molecules.
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