Properties of TaN Thin Films Produced Using PVD Linear Dynamic Deposition Technique

Abstract

Thin tantalum nitride layers were sputtered using Linear Dynamic Deposition (LDD) implemented in the 10 cathode TIMARIS Physical Vapor Deposition (PVD) sputtering equipment from Singulus Nano Deposition Technologies. During the deposition, the wafer is moved in a linear path underneath a rectangular cathode/target which remains stationary and sputtering is performed using a reactive N2/Ar gas mixture. For investigation of the properties of the TaN, layers were deposited with three different final thicknesses of 10, 20 and 50 nm on 200 mm SiO2/Si wafers. Also, the influence of various process parameters like pressure in the deposition chamber and nitrogen flow during the deposition was investigated. The uniformity of the sheet resistance (Four Point Probe), the surface roughness (Atomic Force Microscopy), the thickness uniformity (X-Ray Reflectometry and Transmission Electron Microscopy), the stoichiometry (X-Ray Photoelectron Spectroscopy), and the crystallographic structure (X-Ray Diffraction) of the deposited films were characterized. For the deposited layers, a resistivity in the range from 337 μΩcm to 526μΩcm was achieved for layer thicknesses of 50 nm and 10 nm, respectively. The statistical spread (1σ) of the resistivity within the wafer is in the range of 1% and below. The TaN layers also show excellent thickness uniformity below 0.6% (1σ) and a very smooth surface with roughness below 0.4 nm. According to XPS analysis, the stoichiometry of the thin films was found to be independent of the layer thickness resulting in a tantalum nitride compound with a stoichiometry of TaN. While the stoichiometry of a TaN compound is unaffected, the proportion of the phases and the crystallinity are strictly coupled with the deposition conditions. Very good agreement between different analytical methods with respect to the interrelation of physical properties like sheet resistance of the layers, stoichiometry between Ta and N in the layers, as well as crystallographic structure was achieved. [DOI: 10.1380/ejssnt.2009.277]