Ultralow-dielectric Constant Patterns Fabricated by Nanoimprint Lithography

 

Hyun Wook Ro1, Ken-ichi Niihara2, Ming Liu3, Jae Whan Shim4, Hiroshi Jinnai2, David W. Gidley3, Do Y. Yoon4, Christopher L. Soles1

 

1NIST Polymers Division, 100 Bureau Drive, stop 8541, Gaithersburg, Maryland 20899, USA

2Department of Polymer Science and Engineering, Kyoto Institute of Technology, Kyoto 606-8585, Japan

3Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA

4Department of Chemistry, Seoul National University, Seoul 151-747, Korea

 

 

 

Nanoporous ultralow-dielectric constant (ultralow-k, k<2.0) patterns with half pitch of 100 nm are generated through direct nanoimprint lithography (NIL).  As-cast films prepared from a poly(methylsilsesquioxane) (PMSQ)-based organosilicate (OSG) with a thermally degradable pore-generating molecules (porogen) are directly patterned using a SiO2 mold at 170 oC with 3.4 MPa followed by thermal vitrification at 400 oC under nitrogen environment.  Critical physical properties such as porosity and density as well as pattern shapes are precisely quantified using specular X-ray reflectivity (SXR), X-ray porosimetry (XRP), positronium annihilation lifetime spectroscopy (PALS) and transmission electron microscopy (TEM).  The results indicate that nanoporous line and space patterns are created with high pattern fidelity and reproducibility up to 45 % porogen loading with minimal shrinkage during vitrification process.  As a result, the porosities in patterns are proportional to the loading amount of porogen and the dielectric constants of patterns (k) are estimated to be as low as 1.6.

 

 

 

 

Hyun Wook Ro

Guest Researcher
National Institute of Standards and Technology
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Materials

Mentor: Christopher L. Soles