文档介绍：Nanoporous Polyimides
. Hedrick1, . Carter1, . Labadie1, . Miller1, W. Volksen1, . Hawker1,
. Yoon1, . Russell1, . McGrath2, . Briber3
1 NSF Center for Polymer Interfaces and Macromolecular Assemblies (CPIMA),
IBM Research Division, Almaden Research Center, 650 Harry Road, San Jose,
California 95120-6099, USA
2 Virginia Polytechnic Institute and State University, 2111 Hahn Hall, Blacksburg,
Virginia 24061-0344, USA
3 University of Maryland, 2100 Marie Mount Hall, College Park, Maryland 20742-2115, USA
Foamed polyimides have been developed in order to obtain thin film dielectric layers with
very low dielectric constants for use in microelectronic devices. In these systems the pore
sizes are in the nanometer range, thus the term “nanofoam.” The polyimide foams are pre-
pared from block copolymers consisting of thermally stable and thermally labile blocks, the
latter being the dispersed phase. Foam formation is effected by thermolysis of the thermally
labile block, leaving pores of the size and shape corresponding to the initial copolymer
morphology. Nanofoams prepared from a number of polyimides as matrix materials were
investigated as well as from a number of thermally labile polymers. The foams were char-
acterized by a variety of experiments including TEM, SAXS, WAXD, DMTA, density meas-
urements, refractive index measurements and dielectric constant measurements. Thin film
foams, with high thermal stability and low dielectric constants approaching , can be pre-
pared using the copolymer/nanofoam approach.
Keywords: Nanofoams, Foamed polyimides, Dielectric constants, Microelectronic devices,
Polyimides
1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2 Criteria for High Temperature Polymer Continuous Phase . . . . . 6
3 Criteria for the Thermally Labile Coblock. . . . . . . . . . . . . . . 8
4 Synthesis and Characterization of Polyimide Copolymers . . . . . 16
Thin Film P