Electron microscopy analysis of the microstructure of Ti1-xAlxN alloy thin films prepared using a chemical vapour deposition method

The microstructure of a series of Ti1-xAlxN films prepared by Chemical Vapour Deposition (CVD) is investigated using Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Electron Energy Loss Spectroscopy imaging (EELS). A comparison is made with the microstructure of a film obtained using a magnetron sputtering method. CVD films were prepared with substrate temperatures ranging from 400 to 450 degrees C. Plan-view and cross-sectional observations show that they are made of nanocrystallites, a majority of these being organised in columnar clusters. The sharpest electron diffraction patterns obtained from the films are indexed in terms of the fee TiN structure-type with a lattice parameter a, decreasing slightly with increasing aluminum content. In the film deposited by magnetron sputtering the main structure is fee TiN-type with a lattice parameter of 4.17 Angstrom and the observed grain size is 300 nm, a value much larger than the grain size obtained from CVD films, although the deposition was done at room temperature. The EELS imaging technique also shows that throughout the series, Ti, Al and N are homogeneously distributed. (C) 1998 Elsevier Science S.A.