Residual stress in polytetrafluoroethylene-metal nanocomposite films prepared by magnetron sputtering

In the present research we have evaluated residual stress as well as thermal stability of polytetrafluoroethylene (PTFE) and PTFE-based silver (Ag) nanocomposite films fabricated by dual magnetron sputtering. We used a RF magnetron system for sputtering PTFE, and a DC magnetron sputter source for metal. We have demonstrated that thin nanocomposite films of Ag/sputtered FIFE (thickness 800 to 1100 nm, Ag concentration 3.5 to 24 5%) deposited on silicon are stressed (6 24 to 12.2 MPa) The residual stress depends on the concentration of the nanoparticles Pure sputter deposited FIFE films are under a small tensile stress, which becomes increasingly more compressive upon increasing the filling factor of the metallic nanoparticles. Depending on the concentration of nanoparticles, the residual stress is determined by a thermal component that is sensitive to temperature variation, even in the range of room temperature In the evaluation of the thermal response of the nanocomposite-silicon system, both the changes in the thermal expansion coefficient as well as the elastic modulus of the nanocomposite with the concentration should be taken Into account. (C) 2010 Elsevier B V. All rights reserved.