Study of the influence of Ar on the formation of diamond-like bonds in films obtained from CH4+Ar, RF plasma deposition

摘要

The concentration of the spl bonds in the volume (ratio Phi = N-3 sp(3)/ (N-3 sp(3) + N-2 sp(2) + N-1 sp(1)), where N-1, N-2 and N-3 are the concentrations of sp(1), sp(2) and sp(3) bonds, respectively), is the basic parameter which determines the 'diamond-like' properties of amorphous carbon (a:DLC) films. Electrical, morphological and mechanical properties, as a function of the partial pressure of Ar, of a:DLC films, were measured and their relation to Phi was shown. From Auger electron spectroscopy (AES) data it was shown that the presence of Ar leads to sputtering of the low adhesive carbon atoms from the deposited film, consequently, the a-a:DLC is much more adhesive and harder which make thickness (t) a function of Ar concentration. Ar atoms in the film. were found to be less than 2%. Visible and UV Raman spectroscopy, FTIR and XPS, were used to determine the concentration of sp(3) bonds, (Phi), which was maximum for Ar = 30%. Studies of morphology of the a:DLC films have shown that the average height profile (AHP) obtained from AFM data show an abrupt change for Ar = 30%. Results of electrical and mechanical (microhardness) measurements have shown a maximum value of resistivity (rho = 1.4 x 10(9) Omega cm) and microhardness (H = 2700 kg/cm(2)) is obtained also for Ar = 30%. Since the measurements of Phi is maximum at concentration Ar = 30% and for AHP appears abrupt changes, for rho and H maximum, we may assume that this behaviour of the physical parameter, is due to the diamond-like structure with maximum Phi. The results obtained in this paper also have practical importance since the sample deposited at 30% Ar exhibits 50% sp(3) bonding or more, which is high enough to use this material where diamond-like properties are needed. (C) 2001 Elsevier Science B.V. All rights reserved. [References: 15]