AVS 47th International Symposium
    Processing at the Nanoscale/NANO 6 Tuesday Sessions
       Session NS+NANO6+MM-TuM

Paper NS+NANO6+MM-TuM3
Force-Modulated Nanoindentation of Fluorinated Polymer Thin Films Grown by PECVD

Tuesday, October 3, 2000, 9:00 am, Room 302

Session: Nanomechanics
Presenter: K.J. Wahl, Naval Research Laboratory
Authors: S.A.S. Asif, University of Florida
E.J. Winder, Massachusetts Institute of Technology
K.K. Gleason, Massachusetts Institute of Technology
K.J. Wahl, Naval Research Laboratory
Correspondent: Click to Email
Thin polymer films have been of considerable interest recently in applications for electronics packaging, solid lubrication, MEMS devices, antifouling and adhesives. However, evaluating the mechanical properties of polymer thin films is difficult due to the low elastic moduli and viscoelastic behavior typically observed with polymers. In this paper, we present an approach for measuring the mechanical and dissipative properties of thin, compliant polymer films using AC force-modulated nanoindentation.@footnote 1@ The dynamic response of the indenter is monitored during tip-sample approach, enabling sensitive detection of the surface. Adhesive interactions, contact stiffness and damping are monitored during force-displacement measurements, and hardness and modulus evaluated. In this study, we apply the above approach to investigate the correlation between polymer thin film deposition conditions and the resulting mechanical properties. The thin polymer films were deposited on Si wafers using pulsed plasma-enhanced chemical vapor deposition (PECVD). Two different source gases were used, HFPO (hexafluoropropylene oxide) and HFC-134 (1,1,2,2, tetrafluoroethane); growth conditions were varied by altering the plasma duty cycle during deposition (plasma on-time/plasma off-time). Film thickness was measured by ellipsometry and profilometry, and chemistry examined by XPS and FTIR. Film thickness varied between 100 and 400 nm. Hardness of the films varied between 0.04 to 0.2 GPa, and complex modulus between 2 and 20 GPa, with considerable damping losses observed. Comparisons between the film deposition conditions and resulting chemistry and mechanical properties will be presented and discussed. @FootnoteText@ @footnote 1@ S.A.S. Asif, K.J. Wahl, and R.J. Colton, Rev. Sci. Instrum. 70 (1999) 2408.