Effect of N-containing additive gases on global warming gas emission during remote plasma cleaning process of silicon nitride PECVD chamber using C4F8/O2/Ar chemistry

In this study, remote plasma cleaning process was investigated in a silicon nitride plasma enhanced chemical vapor deposition chamber using C4F8/O2/Ar and C4F8/O2/Ar+additive gas. The remote plasma source used in the present experiments showed the capability of nearly complete destruction, destruction removal efficiency ≅100%, of C4F8 gas with or without the additive N2, N2O and NO gases. The cleaning rate of the silicon nitride layers is increased 32–40% by adding N2, N2O and NO gases to the optimized C4F8/O2 cleaning chemistry. This is presumably due to the effective reaction of NO radicals formed in the remote plasma with N on the silicon nitride surface, followed by the effective fluorination of Si atoms. As a result, the million metric tons of carbon equivalent values could be effectively reduced due to the decreased emission of CF4 as well as the increased cleaning rate of the silicon nitride layers, comparable to those of NF3/Ar remote plasma cleaning. For the effective reduction of global warming effects, the experimental results indicate a possibility of using the alternative gas such as C4F8 with the N-containing additive gases for the environmentally benign remote plasma cleaning process.