Structural and mechanical properties of CNx thin films prepared by magnetron sputtering

In an attempt to define the role of nitrogen in C-N chemical bonding and in the formation of CNx thin films, several coatings with a variable concentr ation of N-2 were group onto (100) Si substrates using magnetron sputtering in N-2/Ar discharge. The chemical composition of the as-deposited films wa s investigated by means of Rutherford backscattering spectroscopy (RBS) and showed an [N]/[C] ratio up to 0.7. Raman and Fourier transform infrared (F TIR) spectroscopy were carried out to measure the optical vibration propert ies for studying the bonding state of nitrogen. By means of grazing incidence X-ray diffraction (XRD) and transmission elec tron microscopy (TEM) electron diffraction the structure of the deposited f ilms was proven to be mainly amorphous containing small crystallites of CNx compounds. Scanning tunneling microscopy (STM) shows the clusterlike surfa ce of the films where the cluster size is characterized by scaling behaviou r. The mechanical properties of the CNx thin films adhering their substrate s were investigated using the nanoindentation technique. From the load-disp lacement curve the hardness H and the Young's modulus E of the films were c alculated. The relationships between deposition parameters and properties of CNx films are shown and discussed. In particular, the influence of the applied r.f. power and the role of the N-2 partial pressure are demonstrated. (C) 2000 E lsevier Science S.A. All rights reserved.