Volume 3, No. 1, June 2003, Pages 53-59 PDF(200 KB)
Decomposition of Boron Trifluoride in the RF Plasma Environment
Ya-Fen Wang1, Cheng-Hsien Tsai2, Lien-Te Hsieh3, Min-Liang Shih1, Wen-Ching Chang1
1 Department of Environmental Engineering and Science, Chia-Nan University of Pharmacy and Science, No. 60, Sec. 1, Erh-Jen Rd., Tainan 717, Taiwan
2 Department of Chemical Engineering, National Kaohsiung University of Applied Sciences, No. 415, Chien Kung Road, 807 Kaohsiung, Taiwan
3 Department of Environmental Engineering and Science National Pingtung University of Science and Technology, 1Hseuh Fu Rd., Nei Pu Hsiang, Ping Tung, 91201, Taiwan
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/O2(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 B2O3(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/O2(glass)/Ar plasma system. However, the amount of decomposed BF3 divided by the input energy (EBF3, energy efficiency) in the BF3/O2(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.
BF3; RF plasma; B2O3; Fine particle.