Diffusion barrier performance of amorphous W–Ti–N films in Cu metallization

Abstract

W–Ti–N films were prepared on a Si wafer by reactive sputter-deposition, followed by a deposition of a Cu thin film by DC magnetron sputtering. The Cu/W–Ti–N/Si samples prepared were annealed at different temperatures under vacuum and then characterized using X-ray diffraction, scanning electron microscopy and auger electron microscopy. The sheet resistivity was determined by four point probe analysis. The results show that the amorphous W–Ti–N film is mainly composed of TiN and W and the crystallization temperature is above 800 °C. W–Ti–N thin films prepared have good thermal stability at 700 °C, but the Cu film tends to agglomerate when the temperature is above 700 °C. A failure mechanism of the diffusion barrier is proposed based on the thermal stress and interface reaction.