Structure and properties of Ta/TaOx barrier films deposited by direct current magnetron sputtering

Double-layer Ta/TaOx films were deposited on glass substrates by direct current magnetron sputtering. The impact of the underlying TaOx on the structure and properties was also investigated using X-ray diffraction analysis, Auger electron microscopy, scanning electron microscopy and atomic force microscopy. This study finds that the structure and properties of Ta/TaOx films depends on the O2 flow during the under-layer TaOx deposition. As the O2 gas flow ratio increases from 3 to 7%, more and more oxidized amorphous TaOx films in the under-layer were formed, which caused the preferred growth orientation of upper Ta films to change from (200) to (221) systematically. Increasing the oxygen flow ratio of under-layer TaOx films also makes the average grain size of upper Ta films decrease from 10.7 to 2.2 nm.