Growth kinetics of sputtered amorphous carbon thin films: composition studies and phenomenological model

The kinetics of carbon sputter deposition on Si(100) substrates were studie d by spectroscopic ellipsometry (SE) and X-ray reflectivity (XRR). The ener gy of ions bombarding the growing film varied by applying a bias voltage on the substrate inducing considerable changes of film density and compositio n. Both SE and XRR detected an initial nucleation stage during which a SiC interlayer was formed. A phenomenological model based on the rate equations for the carbon deposition on Si is proposed to describe the experimental r esults. The model includes the processes of carbon adsorption, formation of SiC and transition from sp(2) to sp(3) sites induced by low-energy ion bom bardment. The calibration of the model was performed with the experimental results regarding the variation of deposition rates. It is shown that the n on-monotonous kinetics of film growth is determined by the variations of su rface composition at different stages of growth. The variation of model par ameters, such as reaction constants and sticking coefficients, during fitti ng the experimental results for various ion energies extracted information regarding the prevailing processes taking place at each stage of the deposi tion process. (C) 2000 Elsevier Science S.A. All rights reserved.