Composition, chemical bonding and mechanical properties of magnetron sputtered CNx thin films at different substrate bias

Nitrogenated amorphous carbon films (a-CNx) were prepared by reactive magne tron sputtering at room temperature with different substrate bias voltage ( V-b) and N concentration in the plasma. In situ spectroscopic ellipsometry (SE) data analysis was used to monitor the composition and the film thickne ss as well as to study the optical properties. The negative V-b was found t o affect the film composition by favoring the formation of sp(2) bond. The chemical bonding in the films was identified by the new Fourier transform I R SE technique. The elastic properties of a-CNx films were also examined an d the results suggest a predominately elastic behavior for films deposited with negative V-b. In addition, stress measurements conducted during therma l annealing up to 300 degrees C, provide the stability of a-CNx films grown with negative V-b. (C) 1999 Elsevier Science Ltd. All rights reserved.