Low temperature deposited Zr–B film applicable to extremely thin barrier for copper interconnect

We have prepared thin Zr–B films at low temperatures as a new material applicable to an extremely thin barrier against Cu diffusion in Si-ULSI metallization. The obtained Zr–B films mainly consist of the ZrB2 phase with a nanocrystalline texture on SiO2 and a fiber texture on Cu. The resistivity of the Zr–B films depends on the substrate of SiO2 or Cu. The constituent ratio of B/Zr is almost 2, though the contaminants of oxygen, nitrogen, and carbon are incorporated in the film. The nanocrystalline structure of the Zr–B film on SiO2 is stable due to annealing at temperatures up to 500 °C for 30 min. We applied the 3-nm thick Zr–B film to a diffusion barrier between Cu and SiO2, and the stable barrier properties were confirmed. We can demonstrate that the thin Zr–B film is a promising candidate for thin film application to a metallization material in Si-ULSIs.