Applicability of ALE TiN films as Cu/Si diffusion barriers

Amorphous TiN films were deposited on a p-(100) Si substrate using an atomi c layer epitaxy technique that employed TEMAT and NH3 as precursors at a te mperature range between 150 and 220 degrees C. The average deposition rate was approximately 4.5 Angstrom/cycle and was in good agreement with the res ult expected from the layer-by-layer growth mode. The deposited TiN films s howed excellent step coverage and uniformity for the trench with a high asp ect ratio of h/w - 2.6:0.43 mu m. The diffusion-barrier behavior of both as -deposited and post-annealed 45-nm thick TiN films at temperatures between 550 and 700 degrees C were investigated against vacuum-evaporated Cu films using sheet resistance measurements, X-ray reflected diffraction, Auger ele ctron spectroscopy, and scanning electron microscopy. The post-annealing of the ALE TiN films in a vacuum chamber of 2 x 10(-6) Torr was not found to be a very sensitive parameter for improving the diffusion-barrier function against Cu and Si; TiN films annealed up to 600 degrees C for 1 h maintaine d the initial composition of both Cu/TiN and TiN/Si interfaces, thereby ind icating a negligible interdiffusion of the Cu and/or Si species through the TiN film. However, a further increase of temperature above 650 degrees C t riggered Si and/or Cu interdiffusion resulting in a probable composition of Cu3Si. (C) 2000 Elsevier Science S.A. All rights reserved.