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Single Step Preparation of Novel Hydrophobic Composite Films for Low‐ k Applications
Author(s) -
Zhu Yongzhong,
Müller Thomas E.,
Lercher Johannes A.
Publication year - 2008
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.200701394
Subject(s) - materials science , composite number , mesoporous material , triethoxysilane , nanoparticle , chemical engineering , porosity , composite material , mesoporous silica , elastic modulus , dielectric , nanotechnology , organic chemistry , chemistry , engineering , catalysis , optoelectronics
Composite films with low dielectric constants ( k ) containing micro‐ and mesopores are synthesized from precursor solutions for the preparation of mesoporous silica and ethanolic suspensions of silicalite‐1 nanoparticles. The material contains silicalite‐1 nanoparticles (include nanocrystals and nanoslabs/intermediates) embedded in a randomly oriented matrix of highly porous mesoporous silica. Micropores result from the incorporated silicalite‐1 nanoparticles, while decomposition of the porogen F127 leads to additional mesopores. The porosity of the composite films increases from 9 to 60% with the increase in porogen loading, while in parallel the elastic modulus and hardness decrease. The elastic moduli of the films are in the range of 13–20 GPa. Hydrophobic surfaces of the composite films are obtained by introducing methyl triethoxysilane during the preparation of both precursor solutions, leading to the incorporation of CH 3 groups in the final composite films. These methyl groups are stable up to at least 500 °C. A low k value of approximately 2 is observed for films cured at 400 °C in N 2 flow, which is ideal for removing templates without decomposing methyl groups. Due to the intrinsic hydrophobicity of the material, post‐silylation is not required rendering the composite films attractive candidates for future low k materials.