Abstract

Clean procedure is one of the major emitters of perfluorinated compounds (PFCs) in semiconductor manufacturing. Nitrogen trifluoride (NF₃) is increasingly the process gas of choice for eliminating PFC emissions. However, its toxic to human and similar global warming potential compared to most other PFCs made NF₃ warranted much more investigation. This study demonstrated a radio-frequency plasma system for decomposing NF₃. The effects of experimental parameters: input power, O₂/NF₃ ratio, operational pressure and NF₃ feeding concentration on NF₃ decomposition fraction (η_NF3) and energy efficiency (E_NF3) were examined in detail. The analytical results demonstrated that the NF₃ was almost completely decomposed (>99%) at input power = 30 W, [NF₃]_in = 1.0% and η_NF3 increased with input power. However, adding O₂ to the system inhibited NF₃ decomposition and decreased E_NF3. Moreover, η_NF3 and E_NF3 decreased with gradually increasing operational pressure. Notably, increasing the NF₃ feeding concentration increased molecule density, reducing η_NF3, but increasing E_NF3. Furthermore, the products detected in the NF₃/O₂/Ar plasma system were NO₂, NO, N₂O, SiF₄, N₂ and F₂. Potential reaction pathways in the oxygen-based NF₃ plasma environment were built-up and elucidated.

Keywords: Nitrogen trifluoride (NF₃); Radio-frequency plasma system; Decomposition fraction; Energy efficiency

Article Outline

1. Introduction

2. Experimental section

3. Results and discussion

3.1. Possible reaction mechanism

3.2. Effect of input power under [NF₃]_in 1% and 1.5%

3.3. Effect of O₂/NF₃ ratios under input power 10 and 20 W

3.4. Effect of operational pressure under input power 10 and 20 W

3.5. Effect of NF₃ feeding concentration under input power 10 and 20 W

4. Conclusions

Acknowledgements

References