AVS 49th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuM

Paper TF-TuM11
Fluorinated Amorphous Carbon Thin Films: Analysis of the Role of the Plasma Excitation Mode on the Structural and Mechanical Properties

Tuesday, November 5, 2002, 11:40 am, Room C-101

Session: Mechanical Properties of Thin Films
Presenter: J.M. Kenny, University of Perugia, Italy
Authors: L. Valentini, University of Perugia, Italy
M.C. Bellachioma, University of Perugia, Italy
S.I.-U. Ahmed, CSEM Centre Suisse d'Electronique et de Microtechnique
G. Bregliozzi, CSEM Centre Suisse d'Electronique et de Microtechnique
Y. Gerbig, CSEM Centre Suisse d'Electronique et de Microtechnique
H. Haefke, CSEM Centre Suisse d'Electronique et de Microtechnique, Italy
J.M. Kenny, University of Perugia, Italy
Correspondent: Click to Email
Fluorinated amorphous carbon (a-C:H:F) thin films were grown using a 13.56MHz radio frequency pulsed plasma source by varying the on-time plasma excitation from 1ms to 0.1s. The effect of the plasma excitation mode on the mechanical and tribological properties of the films was investigated by depth sensing indentation and microfriction tests using a reciprocating microtribometer. Nanoindentation measurements showed increased elasticity of the film, as well as increased hardness upon reduction of the plasma excitation time while a decrease of the friction force was also detected. The structural arrangement of the films investigated by means of thermal induced gas effusion shows that for a plasma excitation time of 1ms the material is relatively compact and the effusion of hydrogen related species (hydrogen molecules and hydrocarbons) dominate. For the highest on-time plasma excitation (0.1s) a strong change in the effusion characteristics indicates that an interconnected network of voids is present. Strong effusion of CF4 related species is found to be consistent with a surface desorption process and can only be observed when the void network dimensions are large enough, i. e., for films deposited with the highest on-time excitation. Raman spectroscopy is successfully applied to corroborate the effusion results indicating a structural transition from diamond-like to polymer-like film with increasing the plasma excitation time.