Increase of cleaning rate and reduction in global warming effect during C_4F_8O/O_2 remote plasma cleaning of silicon nitride by adding NO and N_2O

摘要

During the chemical vapor deposition chamber cleaning and oxide etching processes using perfluorocompounds (PFCs), recombined and non-reacted PFCs are emitted. The emission of PFCs needs to be controlled in the near future to reduce the effect on global warming. In this study, an optimum condition of C_4F_8O/O_2 cleaning chemistry for silicon nitride by using a remote inductively coupled plasma source was determined as a function of process parameters. Under the optimum condition, the net emission of PFCs during cleaning was quantified using a Fourier transform-infrared spectroscopy and then the effects of additive nitrogen-containing NO and N_2O gases on the cleaning rate, the destruction removal efficiency and the million metric tons of carbon equivalent (MMTCE) were investigated. The addition of N_2O and NO gases to C_4F_8O/O_2 cleaning chemistry dramatically increased the cleaning rate by the factor of ≈ 9 and decreased the volume of emitted CF_4 slightly. The increase in the cleaning rate and the decrease in the emitted volume of CF_4 by the addition of N_2O and NO contribute to the large decrease in the MMTCE values by 93 and 95%, respectively, compared to the case of cleaning without the additive gases.