AVS 46th International Symposium
    Manufacturing Science and Technology Group Tuesday Sessions
       Session MS-TuA

Paper MS-TuA2
Patterning of Xerogel in High Density Fluorocarbon Plasmas

Tuesday, October 26, 1999, 2:20 pm, Room 611

Session: Interconnect and Integration
Presenter: T.E.F.M. Standaert, State University of New York at Albany
Authors: T.E.F.M. Standaert, State University of New York at Albany
C. Hedlund, Uppsala University, Sweden
E. Joseph, State University of New York at Albany
G.S. Oehrlein, State University of New York at Albany
W.N. Gill, Rensselaer Polytechnic Institute
P.C. Wayner, Rensselaer Polytechnic Institute
J.L. Plawsky, Rensselaer Polytechnic Institute
Correspondent: Click to Email
The upcoming generations of integrated circuits will employ low dielectric constant (k) materials as interconnect isolation. Compared to conventional oxides, low k materials contribute less to circuit delays. Porous spin-on-glasses (k<2.5), e.g. Xerogel, are of particular interest for high speed devices. We present a detailed study on the patterning of Xerogel films with a porosity varying from 64% to 83%. The films were etched in a high density plasma tool using fluorocarbon gases. This allows for a high etch rate. For example, the etch rates in a CHF@sub 3@ discharge of a 78 % porous Xerogel film and a thermal oxide film are 2750 and 400 nm/min, respectively. The high etch rates can only partially be explained by the porosity of the films. Namely, the etch yield (number of atoms removed per ion impact) varies with porosity. For example, the yields in a CHF@sub 3@ discharge of a 78% porous Xerogel film and a thermal oxide film are 0.88 and 0.58, respectively. One possible explanation for this difference are residual organic groups present in the Xerogel films. We have also characterized the surface modifications after a partial etch by X- ray Photoelectron Spectroscopy (XPS). Finally, we compare the patterning of the Xerogel films to thermal oxides.