Enhancement of the recombination rate of Br atoms by CF[sub 4] addition and resist etching in HBr/Cl[sub 2]/O[sub 2] plasmas.

Mass spectrometry has been used to study the influence of the plasma chamber walls on the recombination rates of halogen atoms in a high density HBr/Cl[sub 2]/O[sub 2]/CF[sub 4] plasma used for silicon gate etching. In these plasmas, CF[sub 4] addition results in a transition from SiO[sub x] to CF[sub x] layer deposition on the chamber walls. We show that this is accompanied by an important enhancement of the surface recombination rate of halogen atoms (specially Br), whose gas phase concentration consequently drops. The same phenomenon is observed when photoresist is etched in an HBr/Cl[sub 2]/O[sub 2] plasma resulting in carbon coating of the chamber walls. This demonstrates that the recombination coefficient of Br atoms on organic polymer surfaces is much larger than on SiO[sub 2]-like surfaces, and that significant consequences on gate etch processes are expected. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]