Thin films of metallic ruthenium were grown by atomic layer deposition (ALD) in the temperature range 275±400 C using bis(cyclopentadienyl)ruthenium (RuCp 2 ) and oxygen as precursors. The ruthenium films were grown on thin Al 2 O 3 and TiO 2 films on glass. X-ray diffraction (XRD) analysis indicated that the films were polycrystalline metallic ruthenium and scanning electron microscopy (SEM) studies showed that the films had excellent conformality. The impurity content of the films, as measured by time-of-flight elastic recoil detection analysis (TOF-ERDA), were very low. All the films had resistivities below 20 lX cm.

Ti(Al)N thin films were deposited by atomic layer deposition (ALD) from titanium tetrachloride, ammonia, and trimethylaluminum. The most important role of trimethylaluminum was to act as an extra reducing agent in order to lower the required deposition temperature. The films were deposited using four different schemes, where the pulsing order and pulse time of the reactants, and the deposition temperature, were varied. The film properties were analyzed by energy dispersive X-ray spectroscopy (EDX), time-of-flight elastic recoil detection analysis (TOF-ERDA), X-ray diffraction (XRD), and resistivity measurements. Additionally, the diffusion barrier properties of selected 10 nm thick films were studied. Both carbon and aluminum were incorporated into the Ti(Al)N films. Despite that, at deposition temperatures of 400 C and lower, Ti(Al)N films exhibited better characteristics than TiN films deposited from titanium tetrachloride and ammonia.

The atomic layer deposition technique was used to deposit TaN thin films from TaCl 5 and TaBr 5 and tert-butylamine or allylamine as a reductive nitrogen source with and without ammonia. The films were characterized with time-of-flight elastic recoil detection analysis, energy-dispersive x-ray spectroscopy, x-ray diffraction, and the standard four-point probe method. The films deposited from tert-butylamine and ammonia with both tantalum precursors had reasonably low halide contents. When allylamine was used as a nitrogen source, on the contrary, the films contained larger amounts of chlorine and other impurities. The resistivity increased markedly as the deposition temperature was decreased. The lowest resistivities (below 1500 ⍀ cm) were obtained when the films were deposited from TaCl 5 or TaBr 5 with tert-butylamine at 500°C.

Ta͑Al͒N͑C͒ thin films were deposited by the atomic layer deposition technique using TaCl 5 or TaBr 5 and NH 3 as precursors and Al͑CH 3) 3 as an additional reducing agent. For comparison TaN thin films were deposited also from TaBr 5 and NH 3 with and without Zn. The films were analyzed by means of the time-of-flight elastic recoil detection analysis, energy dispersive X-ray spectroscopy, X-ray diffraction, and standard four-point probe method. The deposition temperature was varied between 250 and 400°C. The films contained aluminum, carbon, hydrogen, and chlorine impurities. The chlorine content decreased drastically as the deposition temperature was increased. The film deposited at 400°C contained less than 4 atom % chlorine and also had the lowest resistivity, 1300 ⍀ cm. The barrier properties of the Cu/Ta͑Al͒N͑C͒/Si structure were studied by using sheet resistance and X-ray diffraction measurements.

Molybdenum nitride thin films were deposited by the atomic layer deposition technique within a temperature range of 350-500°C from molybdenum pentachloride and ammonia. The films were characterized by time-of-flight elastic recoil detection analysis, X-ray diffraction ͑XRD͒, and standard four-point probe method. MoN x films deposited at 400°C and above had a resistivity below 500 µ⍀ cm and the chlorine content was below 0.3 atom %. The diffusion barrier properties were studied from approximately 10 nm thick MoN x films deposited at 350, 400, and 500°C. Additionally, the barrier tests were performed with Mo͑Ta͒N and Mo͑Ti͒N films deposited at 400°C. The stability of the barrier layer was studied from the annealed Cu/barrier/Si structures by measuring the sheet resistance values, XRD data, and by performing etch-pit tests. Molybdenum nitride showed to be a promising diffusion barrier material. The MoN x barriers deposited at 400 and 500°C were observed to fail only after the annealing at 650°C.The transition from aluminum to copper-based interconnects in next-generations ultralarge-scale integration ͑ULSI͒ microelectronic devices has generated significant challenges for the identification and development of new barrier materials. Copper has many superior properties compared to aluminum, for example higher melting point, lower bulk resistivity, and higher electromigration resistance. But as a drawback, with copper the need of an effective barrier layer is more critical as copper readily diffuses into silicon and insulators and reacts with Si, forming copper silicide phase at as low temperature as 200°C. 1 The barrier material has to fulfill strict demands. 2,3 The barrier may not react with the metal or with the semiconductor, it has to have good adhesion to the adjacent materials, it has to prevent the interdiffusion of metal and silicon, and it has to be stable during the manufacture and operation of the device. Transition metal nitrides, silicides, and silicon-nitrides are considered the most promising diffusion barrier materials. Ti-, Ta-, and W-based materials have received the most interest, whereas the barrier properties of materials based on other transition metals have remained scarcely studied.Molybdenum nitride thin films could be good barriers because these materials possess the aforementioned desired properties of good diffusion barriers. In addition, MoN x is thermodynamically stable toward Cu because of the absence of the Cu-Mo compounds. 4 Only few papers concerning the barrier properties of MoN x thin films have been published. 5-7 The barrier results obtained with the MoN x thin films deposited by physical vapor deposition ͑PVD͒ methods have been promising. Lee and Park, 5 observed that the Cu/␥ = MoN 2 /Si structure remained stable upon annealing at 600°C in vacuum for 30 min, but the structure failed after annealing at 650°C when both molybdenum silicide and copper silicide were formed. The barrier performance of sputter-deposited 50 nm thick Mo-N films was determined by forming Cu/Mo-N/p + n jun...