New method to improve thermal stability in the interface of silicon and tungsten by the interposition of plasma deposited tungsten nitride thin film

Thermally stable tungsten nitride/tungsten bilayer has been proposed for the application of metallization. This bilayer is sequentially formed by plasma enhanced chemical vapor deposition without breaking vacuum. The Rutherford backscattering spectrometry and cross-sectional transmission electron microscopy reveal that the interaction between the W and Si substrate can be prevented by interposing a 800-Å-thick W67N33 layer. The W67N33/W bilayer maintains the integrity of the interface during annealing at 850 °C for 30 min without the formation of Si2W and interdiffusion phenomena. Sheet resistivity of the W67N33/W bilayer is gradually decreased from 17 to 12 μΩ cm at annealing temperatures up to 850 °C.