AVS 53rd International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS1-MoM

Paper PS1-MoM3
Effect of Species Density and Ion Bombardment during Ashing of Extreme Ultra Low-@kappa@ (eULK) Inter-Level-Dielectric (ILD) Materials

Monday, November 13, 2006, 8:40 am, Room 2009

Session: Etch for Advanced Interconnect I
Presenter: M.A. Worsley, Stanford University
Authors: M.A. Worsley, Stanford University
N.C.M. Fuller, IBM Research Division
S.F. Bent, Stanford University
T. Dalton, IBM Research Division
Correspondent: Click to Email
The significance of ion impact and radical species density on ash-induced modification of an extreme ultra low-@kappa@ (eULK) inter-level dielectric (ILD) material (@kappa@ < 2.0) in a patterned single damascene structure exposed to Ar/O@sub 2@ and Ar/N@sub 2@ dual frequency capacitive discharges is determined by combining plasma diagnostics, modeling of the ion angular distribution function (IADF), and material characterization such as angle resolved x-ray photoelectron spectroscopy (ARXPS). Radical species density was determined by optical emission (OE) actinometry under the same conditions and in the same reactor in a previous study by the present authors. ILD modification is observed and correlated with changes in the plasma for a range of pressures (5-60 mTorr), bias powers (0-350W), and Ar in the source gas (0%, 85%). For the Ar/O@sub 2@ discharge, extensive modification of the ILD sidewall was observed for significant ion scattering conditions and vice versa. Further, for an identical increase in the O-radical density (~ an order of magnitude) as pressure or percent Ar was increased, a different degree of modification was induced at the ILD trench bottom surface and seemingly correlated with the relative changes in the ion current for increasing pressure or percent Ar. For the Ar/N@sub 2@ discharge, reduced damage of the ILD sidewall and trench bottom surfaces was observed for increasing pressure (increasing N-radical density) and decreasing ion current to both surfaces. It is, thus, proposed that the mechanism for modification of the porous ILD is dominated by the creation of reactive sites by ion impact under the present conditions. A detailed discussion of the results in relation to this proposal is presented.