Methods of producing ultra -low resistivity tantalum films.

Abstract

We have discovered that, by depositing a tantalum layer upon a substrate at a temperature of at least 325° C., it is possible to obtain an ultra low resistivity which is lower than that previously published in the literature. In addition, it is possible deposit a TaxNy film having an ultra low resistivity by depositing the TaxNy film upon a substrate at a temperature of at least 275° C., wherein x is 1 and y ranges from about 0.05 to about 0.18. These films having an ultra low resistivity are obtained at temperatures far below the previously published temperatures for obtaining higher resistivity films. A combination of elevated substrate temperature and ion bombardment of the film surface during deposition enables the use of lower substrate temperatures while maintaining optimum film properties. In another development, we have discovered that the ultra low resistivity tantalum and TaxNy films produced by the method of the present invention also exhibit particularly low residual stress, so that they are more stable and less likely to delaminate from adjacent layers in a multilayered semiconductor structure. Further, these films can be chemical mechanical polished at significantly higher rates (at least 40% higher rates) than the higher resistivity tantalum and TaxNy films previously known in the industry. This is particularly useful in damascene processes when copper is used as the interconnect metal, since it reduces the possibility of copper dishing during a polishing step.

Dependencies are inferred from the claim text.