Spectroscopic Analysis of NF3 Plasmas with Oxygen Additive for PECVD Chamber Cleaning

As semiconductors' device fabrication is highly integrated, the number of the deposition processes is continuously increasing, and the chamber cleaning process becomes essential for deposition equipment to maintain a normal chamber condition. Although the use of NF3 gas for the chamber cleaning is common, it causes several environmental and safety issues. However, not much research has been performed on NF3 plasma at high pressures, such as in cleaning processes. To understand fluorine in NF3, herein, oxygen was added to N-2 and NF3 plasma and then compared. Plasma emission spectra were compared using an OES data, and their analyses were performed via a line-ratio method employing the collisional-radiative model. As a result confirmed that the changes in electron temperature, electron density, and chemical species in the plasma could be explained. Additionally, the characteristics of NF3 plasmas with respect to fluorine were confirmed by comparing the oxygenated N-2 plasma and the NF3 plasma.