Diffusion Barrier Properties of Metallorganic Chemical Vapor Deposited Tantalum Nitride Films Against Cu Metallization

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Abstract
Films were deposited by chemical vapor deposition using a pentakis(diethylamido)tantalum (PDEAT) source with and without at temperatures ranging from 300 to 375°C. It was observed that both the resistivity and carbon content of the film drastically decreased upon the addition of . For example, the resistivity decreased from 60,000 to 12,000 μΩ cm, and the apparent carbon content obtained by Auger electron spectroscopy decreased from 30 to 1 atom % by the addition of 25 sccm . The grain size initially increased with the addition of 5 sccm in the source gas, but then decreased as the flow rate was increased to more than 10 sccm. As‐deposited film has a face‐centered cubic structure irrespective of the amount of . The density of the film increased from about 5.1 to (bulk density of TaN: ). Barrier failure results identified by the etch‐pit test showed that a 50 nm thickness of the barrier deposited by a single source of PDEAT survived up to 500°C after 1 h annealing. The film deposited with 25 sccm survived up to 550°C after 1 h annealing. However, the step coverage of the films deposited with is drastically decreased, from more than 80% to less than 10% . Thus, while the addition of significantly improves both the resistivity and carbon content in the film, it deteriorates the step coverage of the film. © 1999 The Electrochemical Society. All rights reserved.

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