Kinetic Mechanism of Reactive Oxygen/Nitrogen Species in Plasma-Assisted Greenhouse Gas Replacement

Abstract

In semiconductor manufacturing, greenhouse gases, such as perfluorocarbons (PFCs) and nitrogen trifluoride (NF3), which are sources of global warming, are frequently used to remove substances during cleaning and etching. Particularly, NF3, which has a high global warming potential (GWP) is widely used for chamber cleaning in the chemical vapor deposition (CVD) process. There is an urgent need to replace high GWP gases with eco-friendly gases. In this study, we investigated the possibility of replacing NF3 with N2 gas from the existing NF3/O2 gas mixture during the cleaning process in a plasma-enhanced CVD (PECVD) chamber for the formation of an amorphous carbon layer. The kinetic reaction mechanism of nitrogen-augmented plasma was investigated using ANSYS Chemkin-Pro, and the verification was conducted using an environmentally friendly gas-based direct plasma cleaning process in the PECVD chamber with capacitively coupled plasma (CCP). The verification experiment was conducted with a 150-mm laboratory scale and a 300-mm production equipment. Chemical reaction analysis was then performed to analyze the chemical reaction mechanism in the plasma and identify the trends in the cleaning efficiency. The results derived from the analytical and empirical experiments showed that the addition of N2 positively affected the reaction of O2 in the plasma with surface materials; this improved the cleaning, and the effectiveness of eco-friendly cleaning processes using alternative gases could be confirmed.