| AVS 65th International Symposium & Exhibition | |
| Plasma Science and Technology Division | Monday Sessions |
| Session PS+AS+EM+SS-MoM |
| Session: | Plasma-Surface Interactions |
| Presenter: | Hanyang Li, University of Houston |
| Authors: | H. Li, University of Houston Y. Zhou, University of Houston V.M. Donnelly, University of Houston J. Chiu, MKS X. Chen, MKS |
| Correspondent: | Click to Email |
Fluorine atom-generating plasmas are commonly used in many cleaning processes after chambers have been exposed to a variety of etching and deposition reactants and products. The most common feed gas used in these applications is NF3, due mainly to its ease of dissociation. Repeated processing and chamber cleaning cycles can cause changes in the plasma source, thought to be due mainly to an altering of the nature of the chamber wall protective coatings. In the present study, high power density (5 – 50 W/cm3), low frequency (400 kHz) toroidal inductive plasmas were operated with H2/Ar (4/96 ) and N2/H2/Ar (3/9/88) feed gases for various periods, alternating with exposure to NF3/Ar, O2/Ar, or pure Ar “chamber cleaning” plasmas. H Balmer-alpha optical emission intensity, ratioed to emission from Ar at 750.4 nm, was measured during H2/Ar exposure and the following cleaning plasma. Hydrogen was detected evolving from the anodized Al plasma source wall coating. The decay of intensity ratio of H/Ar increased with increasing H2/Ar plasma exposure. NF3/Ar plasmas enhanced evolution of H, tentatively ascribed to diffusion of F into anodized Al (most likely as F-), which reacts with H that would otherwise remain trapped in the layer. The HF product then out-diffuses, leading to plasma dissociation and H emission. Conversely, O2/Ar plasmas suppressed the evolution of H, presumably because O bonds to Al in anodized Al and ties up hydrogen as bound OH.