| High-quality ZrB2 thin films have been deposited at substrate temperatures as low as 300°C by a new method: remote hydrogen plasma chemical vapor deposition from the single-source precursor zirconium borohydride, Zr(BH 4)4. Carrying out the deposition in the presence of atomic hydrogen generates films with properties that are far superior to those deposited by purely thermal methods; the latter are boron-rich, oxidize readily in air, and adhere poorly to the substrates. In contrast, the films generated at a substrate temperature of 300°C in the presence of atomic H have a B/Zr ratio of 2, a resistivity of 40 μΩ-cm, an oxygen content of ≤4 atomic % and are fully conformal in deep vias. A 20 nm thick amorphous film of ZrB2 on c-Si(001) prevents Cu indiffusion after 30 min at 750°C. We propose that the beneficial effects of atomic hydrogen can be attributed largely to promoting the desorption of diborane from the growth surface. |
