Effect of N-based gases to C₃F₈/O₂ on global warming during silicon nitride PECVD chamber cleaning using a remote plasma source

Silicon nitride cleaning of plasma enhanced chemical vapor deposition (PECVD) chamber was carried out by NF₃ and C₃F₃/O₂ using a remote plasma source. The effects of cleaning gases on the silicon nitride cleaning and perfluorocompounds (PFCs) emission properties were studied. To improve the cleaning properties with C₃F₈/O₂, N-based gases such as N₂, N₂O, and NO were added to an optimized condition of C₃F₈/O₂ (that is, C₃F₈ : O₂= 3:7). The silicon nitride cleaning rate was increased by about 70 % from 260 to 440 nm/min by mixing 5 to 10 % of N-based gases to C₃F₈/O₂ (70 %). Million metric tons of carbon equivalents (MMTCEs) were investigated and MMTCEs were decreased from 1.5 × 10^-10 to 8 × 10^-11 by the addition of 5 to 10 % N-based additive gases to C₃F₈(30% /O₂(70 %). In the case of NF₃, silicon nitride cleaning rate was 900 nm/min and the MMTCE was lower than 5 × 10^-11 at 600 seem of NF₃. Even though N-based gas with added C₃F₈/O₂ shows a higher MMTCE and a lower silicon nitride cleaning rate than those by NF₃, it is believed that N-based gas with added C₃F₃/O₂ is replaceable to NF₃ due to such advantages as relatively low price and low F₂ emission.