Bias Effect on the Microstructure and Diffusion Barrier Capability of Sputtered TiN and TiOxNy Films

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Abstract
The microstructure of TiN and TiO x N y films deposited on Si(100) substrates in an Ar-N2 or an Ar-N2-O2 gas mixture was evaluated with a high-resolution field emission scanning electron microscope (FE-SEM). The TiN films deposited under an applied negative substrate bias have an extremely dense microstructure with hillocks on the film surface caused by the high compressive stress. The addition of oxygen modifies the microstructure of TiN film, i.e., the hillocks disappeared on the surface of TiO x N y by virtue of the stress relaxation effect. It has been found through the experiment of internal thermal diffusion by annealing Al/TiN (or TiO x N y )/Si in a vacuum that the diffusion barrier performance of the films is associated with the microstructure and internal stress in addition to the oxygen content itself.