Ti-Si-N-O barrier films are successfully formed by RE reactive magnetron Sputtering of Ti target with different SiH4 gas flow rate. Si/Ti ratio in the formed film is found to increase with increasing SiH4 gas flow rate. The film resistivity ranges from 3.63 x 10(3) mu Omega cm to 6.45 x 10(6) mu Omega cm due to microstructure variation. X-ray diffraction (XRD) of these films reveals the fort-nation of crystalline titanium nitrides, silicon nitrides and titanium silicide compounds. XPS further unveils that titanium oxide, silicon oxide, and silicon oxynitride compounds are present; however, these non-crystalline compounds are not detectable by XRD. High-resolution transmission electron microscopy (HRTEM) confirms that the film consists of Ti-N, Si-N, and Ti-Si nanocrystals embedded in amorphous matrix. This type of microstructure gives rise to very high stability against copper diffusion tinder bias temperature stressing (BTS) at 200 degrees C and 0.5 MV/cm. Furthermore, this process delivers a very smooth film with surface roughness (RMS) between 2.2 and 3.3 run. Field emission secondary electron microscopy (FESEM) shows a surface morphology of Ti-Si-N-O films with particles size less than 100 nm. By controlling the process parameters, we are able to control the properties of Ti-Si-N-O films as the diffusion property is behaved differently. (c) 2005 Elsevier B.V All rights reserved.