Ultrathin Ta 2O 5 films produced by large-area pulsed laser deposition

Abstract

Tantalum pentoxide (Ta 2O 5) is an important material for the next generation of microelectronics devices. A large-area pulsed laser deposition (PLD) technique was used to uniformly grow ultrathin (5–20-nm-thick) Ta 2O 5 films on silicon wafers of 75 mm diameter, heated to a temperature of 400°C. A KrF excimer laser beam was used to induce the ablation of a target in oxygen gas ambient, at a pressure of 30 mTorr. The large-area coverage was obtained by rastering the laser beam over the radius of the rotating target, while the substrate was rotated simultaneously. The deposition rate was calculated to be 4.8 nm/min. The Ta 2O 5 films were fully dense and amorphous, and excellent uniformity was achieved in terms of structure, composition, thickness and optical properties across every wafer. An investigation of the Ta 2O 5/silicon interface revealed that the growth of the films was accompanied by the formation of a silicon oxide interlayer. This is the first time the PLD technique is demonstrated to produce uniform ultrathin films over large areas (75 mm diameter).