In-situ process monitoring for eco-friendly chemical vapor deposition chamber cleaning

The use of plasma-enhanced chemical vapor deposition (PECVD) has drastically increased the development of 3D-NAND fabrication. We investigated a potential alternative method to replace the usage of NF3 in ACL deposition chamber cleaning with reasonable cleaning efficiency. Perfluoro-compounds (PFCs) have been listed as global warming gases, and NF3, which has 17,200 of 100 years GWP, is expected to be listed in a few years; thus, its usage for PECVD chamber cleaning in the semiconductor and display manufacturing industries may have restricted in the near future. To understand the plasma-cleaning phenomenon inside the PECVD chamber, we monitored the in situ plasma process using optical emission spectroscopy (OES) and quadrupole mass spectroscopy (QMS). The cleaning mechanism was revealed through the chemical species in the plasma using OES, and the presence of harmful gases in the exhaust stage was confirmed using QMS. O2, N2, and NH3 were selected as gases that could replace NF3, and the individual gases, as well as gas mixtures, were analyzed. A mixture of 20% N2 in O2 showed the highest film removal rate in ACL deposition chamber cleaning, and the gas with low GWP was released. Through this study, we propose an eco-friendly chamber cleaning method that can replace the existing method that causes global warming problems.