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

Paper PS-WeA6
Etching Chemistry and Kinetics of BCB Low-k Dielectric Films

Wednesday, October 27, 1999, 3:40 pm, Room 609

Session: Dielectric Etching
Presenter: S.A. Vitale, Massachusetts Institute of Technology
Authors: S.A. Vitale, Massachusetts Institute of Technology
H.H. Sawin, Massachusetts Institute of Technology
Correspondent: Click to Email
Etching of BCB has been performed in a high density inductively coupled plasma reactor using O2 + hydrofluorocarbons, O2 + F2, and O2 + Cl2 chemistries. The etch rates of the films and the selectivities over oxide are correlated to the flux of ions and reactive radicals to the wafer. Species identification and fluxes to the wafer are determined by mass spectrometry, two gridded ion energy and current analyzers, and a Langmuir probe. Etch rates at many points on the wafer are simultaneously measured using Full Wafer Interferometry. Etching yields as a function of ion bombardment energy, neutral/ion flux ratio, and ion impingement angle are quantitatively determined using a novel plasma beam / QCM system. It is proposed that in high density, low pressure plasmas, the etching rate can be limited by the radical flux and by the ion flux to the wafer under different conditions. The selectivity of BCB etching over oxide etching is greatest for etchant gas compositions of approximately 20-40% halogenated gas in oxygen. Selectivity over oxide greater than 20 has been realized with BCB etch rates over 1 um/min . The implications of these results for the integration of BCB as a low-K dielectric into a copper dual damascene architecture are discussed.