Formation of vanadium nitride by rapid thermal processing

In the manufacturing of submicron semiconductor devices rapid thermal processing (RTP) is increasingly applied for annealing and preparation of thin films such as oxides and silicides. We have studied the potential of RTP for the formation of vanadium nitride by nitridation of thin vanadium films in molecular nitrogen. Nitridation in RTP in the temperature range from 900 to 1100 degree C resulted in complete conversion of 200-nm thick vanadium films to vanadium nitride (VN) on a time scale of a few seconds. By contrast, no formation of nitride was observed in comparative experiments (1100 degree C, 1 h) carried out in a conventional furnace. The films were characterized before and after nitridation by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X-ray analysis (EDX) in a scanning electron microscope (SEM) and secondary neutral mass spectrometry (SNMS). Temperature and time dependence of the nitridation process were studied. At temperatures of 950 degree C and below the phase beta -V sub(2)N forms at first and converts into the nitrogen-rich phase delta -VN after continued nitridation. Possible mechanisms for the fast activation of molecular nitrogen in the RTP experiments are discussed.