Nitridation of vanadium in molecular nitrogen: a comparison of rapid thermal processing (RTP) and conventional furnace annealing

The nitridation processes of thin V films in molecular nitrogen at atmosphe ric pressure in a RTP-system, a conventional tube furnace and a high temper ature in situ X-ray diffraction (XRD) reaction chamber with a Pt heating st age were compared. The main differences of these three techniques result fr om their strongly differing heating rates (RTP 50 K/s, in situ chamber 3 K/ s, furnace 0.4 K/s) in combination with effects of traces of oxygen in the N-2 process gas: In the furnace, oxide formation on top of the V film takes place at moderate temperatures during the long heating up period. This oxi de layer acts as diffusion barrier for nitrogen and prevents nitride format ion at higher temperatures. In RTP, due to the fast ramp up to the process temperature no substantial V oxide layer is formed and nitridation of the e ntire V film proceeds rapidly. In the in situ XRD chamber, strong VN peaks show up above 800 degreesC and only a few weak peaks indicate the presence of some oxide too. According to special RTP experiments, UV radiation emitt ed from the tungsten halogen lamps in the RTP system does not play a crucia l role for the activation and dissociation of the molecular nitrogen in RTP , (C) 2001 Published by Elsevier Science Ltd.