Study on the Oxidant Effect for Nitrogen Trifluoride Abatement by Using a 2.45 GHz Microwave Plasma Torch

Abstract

Among the fluorinated compounds (FCs) used in the semiconductor and display industries, NF3 gas is a popular gas for etching processes, and due to the high global warming potential (GWP), emission regulations are becoming more stringent. In the semiconductor process, a point of use (POU) scrubber is attached to the rear stage to remove fluorinated compounds. The field industry continues to increase degassing flow rates and strives to reduce energy consumption for degassing. In order to save energy, researchers have reduced the energy consumption by using a reverse vortex reactor (RVR) and have analyzed the removal efficiency according to the oxidant by using oxygen and steam as additional gases in the gas removal process. Removal rates were measured using Fourier transform infrared (FTIR) spectroscopy and detailed experiments on nitrogen trifluoride (NF3) reduction were performed in terms of the destruction and removal efficiency (DRE). In order to measure the decomposition rate, nitrogen was injected at 250 SLM and NF3 was 1.25 SLM, and the experiment was performed at a concentration of 5,000 ppm. Oxygen and steam were injected as oxidants, and an injection amount was 12 SLM with steam at 2 g/min. In the case of steam injection, there was a difference in the decomposition rate differed according to the injection port, and when injected into the view port (front part of the reactor), the decomposition rates were 90% at 6 kW and more than 98% at 7 kW. When oxygen and steam were used as oxidants, the energy consumption was reduced by 8.3% and 21.4%, respectively, depending on the location at while steam was injected.