Magnetron sputtered carbon nitride: composition and chemical bonding of as-grown and post-annealed films studied with real-time and in situ diagnostic techniques

We prepared CNx films by reactive r.f. magnetron sputtering from a graphite target in a pure N-2 plasma, with different substrate bias voltages (V-b) We studied the optical properties of CN, films by using the in situ spectro scopic ellipsometry (SE) in the energy region 1.5-5.5 eV. The differences i n compositional and bonding configuration between CNx films, provided by th e SE data analysis, are discussed and correlated with the results obtained by Fourier Transform IR SE (FTIRSE) measurements. Postgrowth annealing expe riments were performed in an ultra-high vacuum (UHV) chamber, up to 900 deg rees C. The film modifications and the nitrogen evolution, were monitored i n real-time using an ultra-fast 16-wavelength ellipsometer and a quadropole mass spectrometer (QMS). In situ SE and FTIRSE measurements were also obta ined on the completion of annealing. The nitrogen evolution is correlated w ith the carbon-nitrogen bonding and the compositional modifications in the films, as derived by FTIRSE and SE. (C) 2000 Elsevier Science S.A. All righ ts reserved.