Highly-Conformal TiN Thin Films Grown by Thermal and Plasma-Enhanced Atomic Layer Deposition

Atomic layer deposition (ALD) was used to synthesize highly-conformal titanium nitride thin films using both thermal activation at 250°C and plasma activation at 200°C. Tetrakisdimethylaminotitanium (TDMAT) and ammonia have been utilized as precursors. The evolutions of the thickness and the roughness of the films with the number of ALD cycles have been monitored by spectroscopic ellipsometry and atomic force microscopy, respectively. A slight difference has been observed between thermal and plasma-enhanced ALD TiN films. The chemical composition of the resulting layers for the two activation modes has been investigated by X-ray photoelectron spectroscopy. It indicates a partial oxidation of the film and it shows that the oxide content depends on the activation method and varies with the deposition temperature. The studies of both morphology and crystalline structure carried out by electron microscopy and X-ray diffraction have revealed homogeneous and polycrystalline films for the two activation processes. Electrical measurements have shown that the films grown by plasma-activation exhibit a higher conductivity. Finally, the TiN films were grown on high aspect ratio templates such as anodic aluminum oxide membranes. It demonstrates that highly-conformal TiN thin films can even be obtained by plasma-assisted process within such narrow three-dimensional nanostructures. That was unexpected.