METAL-ORGANIC CHEMICAL-VAPOR-DEPOSITION OF TANTALUM NITRIDE BARRIER LAYERS FOR ULSI APPLICATIONS

Low-resistivity tantalum nitride (TaN) films were deposited by low-pre ssure metal-organic chemical vapor deposition (MOCVD) using a new prec ursor tertbutylimidotrisdiethyl amidotantalum. The surface morphology and the step coverage of TaN films were characterized by scanning elec tron microscopy. The film deposited at 450 degrees C had nearly 100% s tep coverage and the step coverage decreased to 25% for the films depo sited at 650 degrees C, The carbon and oxygen concentrations are about 10 at.% in the CVD TaN films, as determined by Auger electron spectro scopy. From Rutherford backscattering spectroscopy and secondary ion m ass spectroscopy analysis, TaN films were found to be effective diffus ion barriers between aluminum and silicon up to 550 degrees C. The ele ctrical measurements of diode-leakage current indicate that the Al/TaN /Si structure remained stable up to 500 degrees C, after which Al star ted to diffuse through the TaN layer and resulted in a higher leakage current.