Tantalum precursors suitable for chemical vapor deposition of tantalum-containing material, e.g., tantalum, TaN, TaSiN, etc., on substrates. The tantalum precursors are substituted cyclopentadienyl tantalum compounds. In one aspect of the invention, such compounds are silylated to constitute tantalum/silicon source reagents. The precursors of the invention are advantageously employed in semiconductor manufacturing applications to form diffusion barriers in connection with copper metallization of the semiconductor device structure.