Paper TF-WeM4
Conformal Chemical Vapor Deposition of Metal Oxide Thin Films using Metal-Diboranamide Precursors

Wednesday, October 22, 2008, 9:00 am, Room 302

The N,N-dimethyldiboranamide (dmdba) ligand is used to synthesize a wide range of different alkaline earth, transition metal and rare earth metal compounds that have sufficient volatility to serve as precursors for the growth of complex materials by chemical vapor deposition (CVD). In this work, we report the successful growth of TiO₂, erbium-doped TiO₂, MgO, Y₂O₃, La₂O₃ and titanate complex oxides using water as a co-reactant at substrate temperatures as low as 225°C. The growth process is monitored in-situ using spectroscopic ellipsometry, and the films are characterized ex-situ by AES, RBS, SEM, XRD and AFM. The crystallinity of the films upon annealing is also studied. The results show that the metal center has a strong influence in the reactivity, surface chemistry and the vapor pressure of the precursor. The impurity concentrations in the films are below the AES and RBS detection limits, indicating that the dmdba ligand is efficiently released from the growth surface to the gas phase. Under suitable conditions the film growth is highly conformal, e.g. MgO films have been deposited onto trenches with 30:1 depth:width ratio with a step coverage (minimum to maximum thickness ratio) of 90%. The corresponding film growth rate is 5-100 times greater than that achievable using atomic layer deposition due to the uninterrupted nature of the CVD process. These results make the dmdba precursor family very attractive for the synthesis of complex oxide films by CVD.