Characterization of Atomic Layer Deposited Ultrathin HfO_2 Film as a Diffusion Barrier in Cu Metallization

摘要

Thermally stable, amorphous HfO_2 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 HfO_2 films deposited on Si are characterized with X-ray photoelectron spectroscopy. Cu/HfO_2/ samples are annealed at different temperatures, starting from 500 °C, in the presence of N_2 atmosphere for 5 min and characterized using sheet resistance, X-ray diffraction and scanning electron microscopy. Ultrathin HfO_2 films are found to be effective diffusion barrier between Cu and Si with a high failure temperature of about 750 ºC.