Thin Solid Films, Vol.515, No.5, 3030-3039, 2007
Effect of film thickness and the presence of surface fluorine on the structure of a thin barrier film deposited from tetrakis-(dimethylamino)-titanium onto a Si(100)-2 x 1 substrate
The structure of a thin film deposited using tetrakis-(dimethylamino)-titanium (Ti(N(CH3)(2))(4)) as a precursor onto a Si(I 00)-2x1 substrate at ultra-high-vacuum conditions was investigated as a function of film thickness for the films of 20 and 145 nm in the presence of surface copper and fluorine produced by in situ dosing of a common copper deposition precursor, (hexafluoroacetylacetonate)Cu(vinyltrimethylsilane), (hfac)Cu (VTMS), and a hydrogenated form of the hfac ligand, 1, 1, 1,5,5,5-hexafluoro-2,4-pentanedione, hfacH. A combination of surface, depth-profiling, and microscopy analytical techniques suggests that the structure of the titanium carbonitride film depends profoundly on its thickness. While the composition of the film was relatively constant throughout its whole thickness, the nanometer-scale structure changed from amorphous at the top of a 145-nm-thick film, to having a significant amount of small (similar to 5 nm) crystallites closer to the TiCN/Si interface. These studies also confirmed the absence of microfractures in the film prepared by this approach. The ex situ depth profiling investigation suggested that if (hfac)Cu(VTMS) is deposited on a TiCN-precovered silicon substrate and briefly annealed to 800 K, the film acts as a diffusion barrier for copper, while surface fluorine penetrates the film rather easily, resulting in fluorine that is distributed uniformly throughout the film. (c) 2006 Elsevier B.V. All rights reserved.
Keywords:transmission electron microscopy (TEM);X-ray photoelectron spectroscopy (XPS);depth profiling;titanium carbonitride