Applicability of ALE TiN films as Cu/Si diffusion barriers

Abstract Amorphous TiN films were deposited on a p-(100) Si substrate using an atomic layer epitaxy technique that employed TEMAT and NH 3 as precursors at a temperature range between 150 and 220°C. The average deposition rate was approximately 4.5 A/cycle and was in good agreement with the result expected from the layer-by-layer growth mode. The deposited TiN films showed excellent step coverage and uniformity for the trench with a high aspect ratio of h / w — 2.6:0.43 μm. The diffusion-barrier behavior of both as-deposited and post-annealed 45-nm thick TiN films at temperatures between 550 and 700°C were investigated against vacuum-evaporated Cu films using sheet resistance measurements, X-ray reflected diffraction, Auger electron spectroscopy, and scanning electron microscopy. The post-annealing of the ALE TiN films in a vacuum chamber of 2×10 −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°C for 1 h maintained the initial composition of both Cu/TiN and TiN/Si interfaces, thereby indicating a negligible interdiffusion of the Cu and/or Si species through the TiN film. However, a further increase of temperature above 650°C triggered Si and/or Cu interdiffusion resulting in a probable composition of Cu 3 Si.