An Alternative PECVD Chamber Cleaning Gas of COF2 for Low-GWP Consideration

Continuous deposition processes in PECVD environments are critical for ensuring the uniformity and reproducibility of thin films across various applications. Silicon dioxide (SiO2), widely used in these processes for its excellent properties, can leave residual materials in PECVD chambers, leading to material buildup that compromises process consistency and reproducibility. A representative example of compromised process consistency and reproducibility is found in the manufacturing of 3D-NAND flash memory, which involves oxide-nitride (ON) stacking processes. Effective chamber cleaning is essential to ensure consistent and reproducible performance in continuous deposition processes. Nitrogen trifluoride (NF3), a commonly used as chamber cleaning gas, is expected to be newly belong to the greenhouse gas regulations due to its high global warming potential (GWP), which may pose both environmental and industrial risks. In this study, we explored the potential of carbonyl fluoride (COF2) as an alternative chamber cleaning gas with low GWP, albeit with an inferior cleaning rate compared to NF3. This study investigates gas dissociation in the plasma environment and analyzes plasma species and changes in the deposited film surface affecting the cleaning rate. Based on the results, proposed improvements are made to the cleaning process design for COF2, considering factors influencing plasma enhanced chemical vapor deposition (PECVD) chamber cleaning efficiency.