Low temperature plasma-promoted chemical vapor deposition of tantalum from tantalum pentabromide for copper metallization

A low temperature plasma-promoted chemical vapor deposition (PPCVD) process has been developed for the growth of tantalum (Ta) from the halide source tantalum pentabromide (TaBr5), using hydrogen as reducing agent, for incorporation in emerging integrated circuitry (IC) copper metallization schemes. Ta films were produced at substrate temperatures of 400-450 degrees C, reactor working pressures of 0.6-0.7 Torr, hydrogen carrier flow rate of 50 seem, hydrogen reactant flow rates between 200 and 1200 seem, and plasma power ranging from 20 to 100 W, corresponding to a power density of 0.11-0.55 W/cm(2). The films were subsequently characterized by Auger electron spectroscopy (AES), Rutherford backscattering (RBS), x-ray diffraction (XRD), atomic force microscopy (AFM), four-point resistivity probe, scanning electron microscopy (SEM), and cross-section SEM. These studies indicated that the Ta films thus produced were carbon and oxygen free, contained bromine concentration below 2.5 at. %, and exhibited better than 75% step coverage in nominally 0.6 mu m, 2.5:1 aspect ratio, trench structures. (C) 1998 American Vacuum Society.