A study on the bonding structure and mechanical properties of magnetron sputtered CNx thin films

Carbon nitride (CN,) films have been deposited by reactive (RF) magnetron s puttering, in order to investigate the effect of the energetic ion bombardm ent during deposition (IBD), in terms of applied V-b, on their bonding stru cture. Fourier Transform IR Ellipsometry (FTIRE) and X-ray photoelectron sp ectroscopy (XPS) were used for the investigation of the films bonding struc ture, while their mechanical properties were evaluated by nanoindentation m easurements. At films grown with low negative V-b, (low energy IBD) the N a toms are distributed homogeneously in substitutional sites in graphitic rin gs through both sp(2) and sp(3) bonds and in linear chains, through sp(2) b onds. In contrast, the high negative V-b (high energy IBD) has been suggest ed to promote the non-homogeneous N distribution at localized regions in th e films where the formation of sp(3) C-N bonds is favored. This behavior wa s also evidenced by the C1s and N1s XPS peak components, assigned to the sp (3) and sp(2) carbon-nitrogen bonds. Also, high energy IBD films revealed i ncreased values of hardness and elasticity, while hardness values up to 45 GPa were measured at localized regions. (C) 2001 Elsevier Science B.V. ALL rights reserved.