AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS1-WeM

Paper PS1-WeM7
Study of Plasma-Nanoporous Silica Surface Interactions in Fluorocarbon and O@sub2@ Discharges: Comparison with SiO@sub 2@ and Organosilicate Glass

Wednesday, November 5, 2003, 10:20 am, Room 314

Session: Plasma Processing of Nanostructures and Nanomaterials
Presenter: X. Hua, University of Maryland, College Park
Authors: X. Hua, University of Maryland, College Park
G.S. Oehrlein, University of Maryland, College Park
R.M. Briber, University of Maryland, College Park
P. Lazzeri, Center for Scientific and Technological Research, Italy
N. Coghe, Center for Scientific and Technological Research, Italy
M. Anderle, Center for Scientific and Technological Research, Italy
Correspondent: Click to Email
We have investigated plasma surface interactions of nanoporous silica (NPS) films with porosities of up to 50%, SiO@sub 2@ and organosilicate films in either C@sub 4@F@sub 8@/Ar discharges (used for plasma etching) or O@sub 2@ plasmas (used for resist mask removal). Surfaces of the various materials after the above plasma processes were studied by x-ray photoemission spectroscopy as a function of process conditions. In addition, time-of-flight secondary ion mass spectrometry (in static or dynamic mode) was used to obtain additional information on the compounds formed on the surfaces of these materials, or on variations of elemental densities as a function of depth. The plasma-surface interactions of NPS are strongly modified relative to conventional SiO@sub 2@ or OSG. Several depth scales of these alterations exist: The surface and near-surface region (down to ~10 nm), intermediate depth (~50 nm), and the complete NPS film thickness to the interface with the substrate. In the surface/near-surface region the porosity of the NPS material increases the plasma-surface interaction area, which during fluorocarbon etching leads to differences in surface fluorocarbon film coverage for NPS relative to SiO@sub 2@ and associated changes in etching behavior. The larger depth scales are especially relevant for O@sub 2@ cleaning which strongly decreases the residual carbon content of both OSG and NPS down to intermediate depths and for NPS materials of 30% and 50% porosity produces deep penetration of fluorine down to the substrate-interface.