Thermally stable, amorphous HfCh 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 iO2 films deposited on Si are characterized with X-ray photoelectron spectroscopy. Cu/HfO2/ samples are annealed at different temperatures, starting from 500 °C, in the presence of N2 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 °C.
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