AVS 46th International Symposium
    Plasma Science and Technology Division Wednesday Sessions
       Session PS+SS-WeA

Paper PS+SS-WeA2
Desorption Species from Fluorocarbon Film by Ar@super +@ Ion Beam Bombardment

Wednesday, October 27, 1999, 2:20 pm, Room 612

Session: Ion-Surface Interactions II
Presenter: M. Hayashi, Fujitsu Laboratories Ltd., Japan
Authors: M. Hayashi, Fujitsu Laboratories Ltd., Japan
K. Karahashi, Fujitsu Laboratories Ltd., Japan
Correspondent: Click to Email
Fluorocarbon films are formed on wafers and chamber walls in etching processes with fluorocarbon plasmas.@footnote 1,2@ Desorption species from them during etching have a lot of influences on Si device fabrication, for example, formation of side wall protection films in etched holes and fluctuation of plasma components in the near-surface region of a wafer. We succeeded in detecting the species that are desorbed from fluorocarbon films by ion bombardment. In this study, we constructed a new apparatus in order to investigate desorption species from fluorocarbon films. The measured fluorocarbon films were deposited on a Si wafer by exposing it to a C@sub 2@F@sub 6@ plasma in an inductively coupled plasma (ICP) reactor. The species desorbed by Ar@super +@ ion beam bombardment at a few keV into the films were detected using a quadrupole mass spectrometer (QMS). The film characteristics were evaluated simultaneously by x-ray photoelectron spectroscopy (XPS), and we discuss the correlation between the desorption species and the film characteristics. QMS spectra that were measured during the Ar@super +@ ion beam bombardment of the fluorocarbon films show many sorts of dissociated C@sub x@F@sub y@. CF@sub 3@@super +@ is a dominant QMS peak in the fragment pattern, and this indicates that CF@sub 4@ is a dominant desorption species. Besides, some large desorption species are recognized because of the detected large fragment ions of C@sub 3@F@sub 3@@super +@, C@sub 3@F@sub 5@@super +@, and so on. The ratios among CF, CF@sub 2@, CF@sub 3@, and CF@sub 4@ species, which were measured with the appearance energies, indicate that CF@sub 4@ is a dominant desorption species with the ratio of 80 % among them at the beginning of bombardment. However, continuous ion bombardment causes the CF ratio to increase instead of decrease in the CF@sub 4@ ratio. This demonstrates the change in film characteristics from F-rich to C-rich, which was evaluated by XPS measurement. Moreover, The formation of C-rich film also corresponds to a reduction in total amount of desorption species. @FootnoteText@ @footnote 1@K. Takahashi, M. Hori, and T. Goto, J. Vac. Sci. Technol. A 14, 2011 (1996). @footnote 2@T. Shirafuji, W. W. Stoffels, H. Moriguchi, and K. Tachibana, J. Vac. Sci. Technol. A 15, 209 (1997).