UV annealing of ultrathin tantalum oxide films

Tantalum pentoxide (Ta2O5) thin films with different thicknesses of around 100, 170 and 660 Å have been grown on 4-in. p-type (1 0 0) Si wafers by photo-induced chemical vapor deposition and then annealed at low temperature (350 °C) using 172 nm excimer lamps. High film uniformity across the wafers with a thickness variation of not more than ±2.5% was readily achieved for all the as-deposited films. Improved leakage current densities down to 1.2×10−8 A/cm2 at an electric field of 1 MV/cm were obtained in 100 Å thick films upon annealing. The optimum annealing conditions were found to vary among these films with an annealing time of ∼5 min being most effective for 100 Å thick layers, while 20 min or more was required for films thicker than 660 Å.