Degradation and stress evolution in a-C, a-C : H and Ti-C : H films

Presented in this contribution are some observations of the stress evolutio n and degradations of diamond-like a-C, a-C:H and Ti-C:H (10-20 at.% of Ti) films deposited by magnetron sputtering of the C or Ti target in the Ar or Ar + CH4 gas mixture, The compressive stresses increased during several da ys for all the Ti-C:H films regardless of their structure (amorphous or a-C :H with TiC nanocrystalline inclusions) and composition (10-20 at.% of Ti). This phenomenon was not observed for a-C and was slightly displayed for a- C:H films having high hydrogen content. The growth of stress was accompanie d by it decrease of optical constants, n and k. Simultaneously, Raman spect ra and composition of Ti-C:H films remained unchanged. The degradation in a mbient air during several hours or days takes place mostly for the films pr epared by reactive sputtering in the Ar + CH4 gas mixture, while a-C films, sputtered from the C target in argon, demonstrated stable behavior despite their high compressive stress level. (C) 2001 Elsevier Science B.V. All ri ghts reserved.