AVS 49th International Symposium
    Dielectrics Thursday Sessions
       Session DI+EL-ThA

Paper DI+EL-ThA7
Materials Transformation and Kinetics in the Formation of Porous Low-K Polymer Dielectrics for Advanced Interconnect Technology

Thursday, November 7, 2002, 4:00 pm, Room C-107

Session: Processing and Properties of Dielectric Materials
Presenter: P. Lazzeri, ITC-irst, Italy
Authors: P. Lazzeri, ITC-irst, Italy
L. Vanzetti, ITC-irst, Italy
M. Bersani, ITC-irst, Italy
M. Anderle, ITC-irst, Italy
J.J. Park, University of Maryland
Z. Lin, University of Maryland
G.Y. Yang, University of Maryland
R.M. Briber, University of Maryland
G.W. Rubloff, University of Maryland
R.D. Miller, IBM Research
Correspondent: Click to Email
The advance of Si ULSI technology requires the integration of very low K materials (i.e., low dielectric constant) into Cu Damascene interconnect schemes. To produce such low-K materials spin-casting and curing of multi-component polymeric precursor materials to form nanoporous films through selective degradation of one of the components (termed the porogen) is an attractive option, but process reproducibility and control, microstructure, and sensitivity to contaminating ambients during processing all present serious manufacturability challenges. We have used time-of-flight SIMS (ToF-SIMS) and XPS to investigate the chemical composition of a leading low-K candidate, polymethylsilsesquioxane (PMSSQ), and porous versions of PMSSQ, as a function of curing treatment to characterize reaction kinetics which accompanies formation of the low-K matrix and evolution of the volatile porogen to form a nanoporous microstructure. The PMSSQ matrix, with an average composition of Si(CH3)O1.5, shows only small changes in chemical composition upon curing. The formation of the nanoporous PMSSQ involves the degradation of the added porogen, poly(methylmethacrylate-co-dimethylaminoethylmethacrylate) (PMMA-co-DMAEMA) at elevated temperatures. The degradation products of the porogen are also evaluated by means of ToF-SIMS. The loss of the porogen and the evolution of the contaminants upon curing are observed to primarily occur in the range 125-450°C. These results show that such surface analysis methods may reveal the kinetics of critical materials transformations in these complex inorganic-organic hybrid systems, which are required for establishing the manufacturability of porous low-K dielectrics.