AVS 50th International Symposium
    Manufacturing Science and Technology Monday Sessions
       Session MS-MoM

Paper MS-MoM3
Processing and Characterization of PMSSQ Based Materials for Nanoporous Low-K Dielectrics

Monday, November 3, 2003, 9:00 am, Room 309

Session: Process and Equipment Integration and Development
Presenter: P. Lazzeri, ITC-IRST, Italy
Authors: P. Lazzeri, ITC-IRST, Italy
J.J. Park, University of Maryland
Z. Lin, University of Maryland
R.M. Briber, University of Maryland
L. Vanzetti, ITC-IRST, Italy
M. Anderle, ITC-IRST, Italy
M. Bersani, ITC-IRST, Italy
R.D. Miller, IBM Almaden Research Center
G.W. Rubloff, University of Maryland
Correspondent: Click to Email
Nanoporous low-K dielectrics are an essential component in future interconnect technology. We have investigated the thermal transformations by which nanoporous polymethylsilsesquioxane (PMSSQ)-based low-K dielectrics are formed through spin-casting and curing in a mixture of PMSSQ with a poly(methylmethacrylate-co-dimethylaminoethylmethacrylate) random copolymer (PMMA-co-DMAEMA) as the porogen. ToF-SIMS shows a sequence of PMSSQ fragments which change with curing, as well as the evolution of porogen related species. Over the range 200-450C, both crosslinking to form the SiO@sub 1.5@CH@sub 3@ matrix and decomposition/volatilization of the porogen occur. To understand the influence of PMSSQ precursor chemistry on the final low-K structure, we have compared two precursors with different initial SiOH content. ToF-SIMS shows the crosslinking kinetics to be faster for the high SiOH than for the low SiOH content material. The distribution of the porogen species also varies with the nature of the PMSSQ precursor: XPS reveals substantial surface depletion of porogen for the low SiOH but not for the high SiOH content material, and ToF-SIMS images indicate the formation of large porogen aggregates, but only for the low SiOH material. Thermal desorption mass spectrometry during curing shows the evolution of volatile byproducts, as expected for both the crosslinking reactions and the porogen degradation and desorption. These chemical analysis techniques yield information crucial to understanding the complex chemical and transport phenomena which determine the microscale and nanoscale properties of these nanoporous low-K dielectrics and their role in future interconnect technology.