STRESS-RELAXATION IN PLASMA-DEPOSITED TUNGSTEN NITRIDE/TUNGSTEN BILAYER

The evolution of tensile to compressive stress has been found in plasma enhanced chemical vapor deposited W thin films incorporated with N atoms. The magnitude of stress varies from 6.25 x 10(9) to -7.79 x 10(9) dyne/cm2, corresponding to an increase of N atoms. In order to reduce the high tensile stress of a W film, W67N33 is interposed between W and Si. As a result, the stress of the W67N33/W bilayer relaxes from 7.98 x 10(9) to 3.41 x 10(9) dyne/cm2 after annealing at 900-degrees-C for 30 min, which is ascribed to the interfacial pseuododiffusion layer formed at the interface of W and W67N33.