Stability, enhancement of elastic properties and structure of multilayeredamorphous carbon films

The growth of sputtered amorphous carbon (a-C) films in layer structure wit h alternating (negative/positive) substrate bias voltage V-b, was applied t o control their intrinsic stress level and stability. The main benefit of t he process was the development of thick, stable, hard and rich in sp(3) sit es films proving their usefulness for many practical applications. In order to investigate the structure and the mechanisms of film stability we perfo rmed in-situ Spectroscopic Ellipsometry, Stress, Nanoindentation, Raman and Transmission Electron Microscopy (TEM) measurements. The latter provides d etails about the layered structure of the films. A stress relief was found to occur in films depending on the sequence of layers and their modulation period. Despite the film stability an improvement in film hardness and elas tic modulus was also achieved, whereas nanocrystalline carbon phases were d etected and identified by Raman spectra. (C) 1999 Elsevier Science B.V. All rights reserved.