Interfacial reactions between Al and RuO 2 , MoO x and WN x diffusion barriers on Si

The Interfacial reactions between Al and RuO 2 , MoO x and WN x diffusion barriers on Si (100) wafers have been studied. The diffusion barrier structures were analyzed before and after various heat treatments using Auger electron spectroscopy (AES) and cross‐sectional transmission electron microscopy (XTEM). Al was found to reduce the oxides of both Ru and Mo. A 100 Å thick Al 2 O 3 layer developed between the Al and the RuO 2 films during annealing at 500°C for 30 minutes. The formation of interfacial Al 2 O 3 efficiently prevents Al penetration but may cause a too high contact resistance for applications in contact structures of microelectronic devices. The WN x barrier was stable after annealing at 600°C for 30 minutes, if the film was exposed to air prior to Al deposition. If, instead, the Al was deposited in situ , the structure failed after annealing at 500°C due to a reaction between Al and W giving WAl 12 . A thin Al 2 O 3 layer was detected between the Al and the WN x films of the air exposed sample. This layer had the effect of retarding the Al–W reaction and thereby raised the failure temperature of the barrier by at least 100°C.