Barrier metal properties of amorphous tantalum nitride thin films between platinum and silicon deposited using remote plasma metal organic chemical vapor method

Abstract

Amorphous TaN thin films have been prepared by remote plasma-assisted metal organic chemical vapor deposition using pentakis-dimethyl-amino-tantalum (PDMATa) in hydrogen plasma. The dependence of film properties such as resistivity, impurity contents, and microstructures on deposition conditions is reported. All obtained films have been tested as diffusion barriers between platinum and silicon in a stacked-capacitor type memory cell for future, high-density ferroelectric memories. X-ray photoelectron spectroscopy (XPS) has been used to determine the nature of carbon incorporation into the film, which is responsible for the observed microstructure of the deposited film. Recrystallization occurs at an annealing temperatures of 1000 degrees C in an oxygen-containing (10%) ambient, showing (111) TaN, [bcc] Ta, and orthorhombic Ta2O5. It was determined that a TaN barrier layer can be successfully applied as a barrier layer between platinum and silicon (700 degrees C for 30 min in an oxygen-containing ambient), preventing the silicidation reaction of silicon with a Pt electrode as well as the oxidation of the underlying capacitor electrode during the capacitor formation process.