ION-BEAM ANALYSIS OF DIAMOND-LIKE CARBON-FILMS

Diamond-like carbon films are deposited with a number of different met hods. This results in a wide variety of different microstructures and even compositions of the films, which challenges characterization capa bilities, Ion beam analysis can be used in many ways to probe the prop erties of the films. A classic application is the determination of hyd rogen concentrations in hydrogenated amorphous carbon films, a-H:C, Th is is performed by using either a resonance of the nuclear reaction H- 1(N-15, alpha gamma)C-12 or a forward recoiling technique. Diamond-lik e films have been doped with metals, Si, F, etc, in order to modify me chanical, tribological, or optical properties. Dopand concentrations c an be qualitatively measured using either a backscattering or nuclear reaction analysis (NRA) method, A fairly trivial application is the ut ilization of either Rutherford or non-Rutherford backscattering to obt ain the number of carbon atoms per square centimetre. Combined with ot her information on the chemical composition of the film and with the t hickness obtained with a profilometer, for example, the density of the very thin films can be calculated. The density is an interesting para meter of the films and may vary considerably, depending on the hydroge n concentration and the structure of chemical bonding. If the thicknes s of the films is not constant or if a diamond-like material is just a deposition with an irregular shape, the above method cannot be utiliz ed. The ion beam technique may still be useful and the Doppler shift a ttenuation of the resonance can be used. Resonance techniques are usef ul in analysing some other carbon related films, for example in analys ing nitrogen in CNx films. in this paper, the most useful ion beam tec hniques for analysing diamond-like materials are given with examples.