Effect Of Nh3 Thermal Treatment On An Atomic Layer Deposited On Tungsten Films And Formation Of W-B-N

The effect of ammonia (NH3) ambient annealing on a tungsten (W) film deposited by atomic layer deposition at temperatures ranging from 400-700degreesC is discussed. The as-deposited film contains approximately 20 at. % of boron which is chemical bound to W (W-B) having a resistivity of 128 muOmega cm. The film has an amorphous structure, which does not transform into crystalline phase during annealing. As a result of annealing in NH3 ambient, a tungsten ternary phase (W-B-N) forms at the surface; its binding configuration depends on the annealing temperature. Below 500degreesC, nitrogen is chemically bonded to tungsten (W-N) while maintaining a W-B bond. Above 600degreesC, nitrogen-rich W-B-N forms, in which nitrogen atoms have chemical binding with boron (B-N) and tungsten (W-N). It was found that a film annealed at higher temperatures has a resistivity of 107 muOmega cm, and thermal desorption of boron and nitrogen containing species is not observed during the thermal process. In addition, tungsten oxide formed at the surface during exposure to air is reduced during the NH3 annealing process. X-ray photoelectron spectroscopy, x-ray diffraction, transmission electron microscopy, and thermal desorption spectroscopy were used for film characterization. (C) 2003 American Vacuum Society.