Ultrathin Ta2O5 films produced by large-area pulsed laser deposition

Tantalum pentoxide (Ta2O5) is an important material for the next generation of microelectronics devices. A large-area pulsed laser deposition (PLD) te chnique was used to uniformly grow ultrathin (S-20-nm-thick) Ta2O5 films on silicon wafers of 75 mm diameter, heated to a temperature of 400 degrees C . A KrF excimer laser beam was used to induce the ablation of a target in o xygen gas ambient, at a pressure of 30 mTorr. The large-area coverage was o btained by rastering the laser beam over the radius of the rotating target, while the substrate was rotated simultaneously. The deposition rate was ca lculated to be 4.8 nm/min. The Ta2O5 films were fully dense and amorphous, and excellent uniformity was achieved in terms of structure, composition, t hickness and optical properties across every wafer. An investigation of the Ta2O5/silicon interface revealed that the growth of the films was accompan ied by the formation of a silicon oxide interlayer. This is the first time the PLD technique is demonstrated to produce uniform ultrathin films over l arge areas (75 mm diameter). (C) 2000 Elsevier Science S.A. All rights rese rved.