Characterization of atomic layer deposited ultrathin HfO2 film as a diffusion barrier in Cu metallization

Thermally stable, amorphous HfO2 thin films deposited using atomic layer deposition have been studied as a diffusion barrier between Cu and the Si substrate. 4 nm thick as-deposited HfO2 films deposited on Si are characterized with X-ray photoelectron spectroscopy. Cu/HfO2/< Si > samples are annealed at different temperatures, starting from 500 degrees C, in the presence of N-2 atmosphere for 5 min and characterized using sheet resistance, X-ray diffraction and scanning electron microscopy. Ultrathin HfO2 films are found to be effective diffusion barrier between Cu and Si with a high failure temperature of about 750 degrees C.