US EPA

4007682 

Journal Article 

CF4 decomposition of flue gas from semiconductor process using inductively coupled plasma 

Kuroki, T; Mine, J; Odahara, S; Okubo, M; Yamamoto, T; Saeki, N 

2005 

Yes 

I E E E Transactions on Industry Applications
ISSN: 0093-9994 

41 

1 

221-228 

English 

10.1109/TIA.2004.840954 

WOS:000226675900028 

Flue gases from the semiconductor process, SF6, NF3, perfluorocarbons (PFCs) such as CF4 and C-2 F-6, and hydrofluorocarbons such as CHF3 are being regulated internationally because their gases have extremely large global warming potential in comparison to CO2, and they have a long lifetime. PFCs are used for wafer etching and cleanup of chemical vapor deposition chambers. CF4 is one of the most stable gases among PFCs and its decomposition is extremely difficult. The purpose of this paper is to develop a PFCs removal system which can be used as the same power supply for both plasma -processing and a CF4 emission cleanup system in semiconductor manufacturing processes. This achieves higher efficiency and is more economical than conventional systems. CF4 decomposition was investigated at low pressure (29 - 53 Pa) using the inductively coupled plasma (ICP) reactor. When the total flow rate was below 0.189 normal liters per minute and O-2 concentration exceeded the 0.9 stoichiometric ratio, the complete CF4 decomposition efficiency was achieved at 1.2 M The amount of O-2 should be a 1 similar to 1.45 stoichiometric ratio of CF4 to achieve good CF4 decomposition. The argon enhanced the decomposition of CF4- On the other hand, the helium was insignificant. CF4 decomposition efficiency decreased in the presence of N-2. For CF4 decomposition, the energy efficiency for CF4 decomposition was 21.0 g/kWh at optimal condition using the ICP reactor. From the Fourier Transform Infrared Spectrophotometer analysis, CO and carbonyl fluoride (COF2) were produced except for CO2. COF2 is toxic, however, it hydrolyzes into HF and CO2, so it is easy to eliminate COF2 using the scrubber which was located downstream of the dry vacuum pump. 

CF4; decomposition; hydrofluorocarbons (HFCs); inductively coupled plasma (ICP); perfluorocarbons (PFCs)