Crystallization of amorphous WNx films

The microstructural changes of WNx films during annealing were analyzed usi ng transmission electron microscopy and x-ray diffraction. Amorphous WNx fi lms eventually crystallized to a two-phase mixture of W and W2N through the primary crystallization and eutectic crystallization. The resulting micros tructure after annealing at 800 degreesC consisted of large primary crystal s with a eutectic mixture of W and W2N microcrystallites in the intergranul ar boundary region. In case of the amorphous film with near-eutectic compos ition of W0.79N0.21, it transformed directly into a two-phase mixture of W and W2N through the eutectic crystallization at 600 degreesC without the pr imary crystallization. On the other hand, polycrystalline W2N films had a c olumnar structure and did not undergo any microstructural change during ann ealing up to 800 degreesC. Barrier properties of WNx film versus Cu diffusi on are discussed in relation with the microstructural changes of the films. (C) 2001 American Institute of Physics.