Preparation of thermally stable low-k thin films using C₆F₆ plasma

−Gas phase diagnostics and characterization of film structure−

Abstract

The chemical structure of low-k films has shifted from a pure amorphous structure to a structure including several functional groups. Such a strategy has mainly been applied for the preparation of novel nano-porous SiOC films. We demonstrate that the thermal stability of fluorinated amorphous carbon (a-C : F) films can be improved by the same strategy while maintaining a low dielectric constant. For the first example of incorporating a functional group in an a-C : F structure, we demonstrate that benzene ring structures can be incorporated in a-C : F films, and that the films show a low-k value of 2 and high thermal stability up to 400°C. Film deposition mechanisms are also discussed on the basis of gas phase diagnostics using in situ Fourier-transform infrared spectroscopy.