Properties of Plasma-Enhanced Atomic Layer Deposition-Grown Tantalum Carbonitride Thin Films

Abstract

Tantalum carbonitride thin films were deposited by plasma-enhanced atomic layer deposition using the metallorganic precursor tert-butylimido tris (diethylamido) tantalum and hydrogen/argon direct plasma with 600 W radio frequency power. Within the atomic layer deposition temperature window, which ranges from below 200 to 260 degrees C, films grow with similar to 0.35 angstrom/cycle. At a substrate temperature of 250 degrees C, the process yields Ta2CN films with an oxygen impurity content of below 5 atom %. These films have a cubic nanocrystalline structure, a high density of 13-14 g/cm(3), as well as an excellent low resistivity of 160 mu Omega cm. Furthermore, the films show copper diffusion barrier performance comparable to stoichiometric physical vapor deposition TaN and a feasible wetting on multiwall carbon nanotubes. The interface between the tantalum carbonitride film and the silicon substrate was investigated using analytical electron microscopy and shows nitrogen and carbon agglomeration.