Spectroscopic ellipsometry characterization of diamond-like carbon films formed by filtered arc deposition

The properties of diamond-like carbon (DLC) films can vary widely from grap hite (sp? local bonding) to diamond (sp(3) local bonding), strongly dependi ng on the film preparation conditions. As the optical constants (n, k) of s p(3) bonded carbon are quite different from those of sp? bonded carbon over the visible and near-infrared (VIS-NIR) spectral range, it is possible to provide precise quantitative information on sp(3) C (sp(2) C) fractions usi ng optical characterization methods. In the present work, spectroscopic ell ipsometry (SE) using multiple sample analysis method has been applied to st udy a series of DLC films on silicon substrates prepared by filtered are de position (FAD) technique. In contrast to most reported SE studies, the DLC film was simulated by a mixture of sp(3) C, sp! C and void constituents ins tead of treating it as a whole. From the interpretation of SE spectra, the film thickness and the volume fractions of sp(3) C, sp(2) C and void have b een derived, respectively. In addition, comparison between SE results and R utherford backscattering spectroscopy (RBS) and electron energy loss spectr oscopy (EELS) results will be given. This work shows that SE using multiple sample analysis method is a very useful optical method to determine sp(3) C fractions in DLC films. (C) 2000 Elsevier Science B.V. All rights reserve d.