Decomposition of Boron Trifluoride in the RF Plasma Environment

Received: May 31, 2003
Revised: May 31, 2003
Accepted: May 31, 2003
Download Citation: RIS|BibTeX|https://doi.org/10.4209/aaqr.2003.06.0006  

Cite this article:
Wang, Y.F., Tsai, C.H., Hsieh, L.T., Shih, M.L. and Chang, W.C. (2003). Decomposition of Boron Trifluoride in the RF Plasma Environment. Aerosol Air Qual. Res. 3: 53-59. https://doi.org/10.4209/aaqr.2003.06.0006

ABSTRACT

Boron trifluoride (BF₃) is the most commonly used gas for implanting ions of the N-type dopant boron. BF₃ is non-flammable and does not support combustion, but is toxic when inhaled and corrosive to the skin. A radio frequency (RF) plasma system used to decompose BF₃ was examined. The BF₃ decomposition fractions (_ηBF3) were determined in effluent gas streams of BF₃/CH₄/Ar, BF₃/O₂/Ar and BF₃/O_2(glass)/Ar plasma systems. The by-products detected in the BF₃/CH₄/Ar plasma system were CO, CO₂, SiF₄, HF and boron-carbon compounds. The by-products detected in the BF₃/O₂/Ar plasma system were B₂O_3(s) and SiF₄. The _ηBF3 in the BF₃/CH₄/Ar plasma system was 49.8%, higher than that in the BF₃/O₂/Ar and BF₃/O_2(glass)/Ar plasma system. However, the amount of decomposed BF₃ divided by the input energy (E_BF3, energy efficiency) in the BF₃/O_2(glass)/Ar plasma system was greater than that in the BF₃/CH₄/Ar and BF₃/O₂/Ar plasma systems. Moreover, the photo images of depositions of different reacting gases O₂, H₂ with BF₃ were also compared. The reaction in the BF₃/O₂/Ar plasma system generated B₂O₃ fine particles and led to the deposition of a white substance on the surface of the reactor. The _ηBF3 was only around 25% for mixing with O₂, even when the input power exceeded 120 Watts, but the generation of fine particles in the system warrants much more investigation.

Keywords: BF3; RF plasma; B2O3; Fine particle