Impurity behaviors of nitrogen in W–C–N thin diffusion barriers for Cu metallization schemes
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To investigate the effect of nitrogen impurities in the tungsten–carbon thin films, the electrical and structural properties of W–C–N thin films deposited with rf magnetron sputtering method were measured. Interface characteristics of W–C–N/Si were studied with resistivity and crystal structure as a function of nitrogen impurity concentrations of as-deposited and annealed state for various annealing temperature. We also investigate the interface of Cu/W–C–N/Si for various nitrogen concentration by using XRD pattern and Nomarski microscope. Our experimental results indicate that nitrogen impurity provides stuffing effect for preventing the interdiffusion between Cu and Si interface after annealing up to 800°C for 30 min, because W–C–N thin films serve as a good diffusion barrier and this may be due to the role of nitrogen and carbon inside the W–C–N film not as bonded state but impurities
KeywordsW–C–N thin film Diffusion barrier Copper metallization
This work was financially supported by research program 2007 of Kookmin University in Korea.