The location and effects of Si in (Ti1-xSix)N-y thin films

• (Ti1-xSix)N-y (0 andlt;= x andlt;= 0.20; 0.99 andlt;= y(x) andlt;= 1.13) thin films deposited by arc evaporation have been investigated by analytical transmission electron microscopy, x-ray diffraction, x-ray photoelectron spectroscopy, and nanoindentation. Films with x andlt;= 0.09 are single-phase cubic (Ti,Si)N solid solutions with a dense columnar microstructure. Films with x andgt; 0.09 haven a featherlike microstructure consisting of cubic TiN:Si nanocrystallite bundles separated by metastable SiNz with coherent-to-semicoherent interfaces and a dislocation density of as much as 10(14) cm(-2) is present. The films exhibit retained composition and hardness between 31 and 42 GPa in annealing experiments to 1000 degrees C due to segregation of SiN, to the grain boundaries. During annealing at 1100-1200 degrees C, this tissue phase thickens and transforms to amorphous SiNz. At the same time, Si and N diffuse out of the films via the grain boundaries and TiN recrystallize.

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