Ultrathin high-quality tantalum pentoxide films grown by photoinduced chemical vapor deposition

Ultrathin tantalum pentoxide films with thicknesses between 4 and 9 nm, equ ivalent to SiO2 thicknesses between 1 and 3 nm, as required for the next ge neration ultralarge-scale-integrated gate insulators, have been grown by th e promising technique of ultraviolet-assisted injection liquid source chemi cal vapor deposition (CVD) at low temperature (350 degreesC). Optical band gap energies of 4.14 +/-0.08 eV, fixed oxide charge content in the range of 1x10(11)-8x10(10) cm(-2), and leakage current densities as low as 5.0x10(- 8) A/cm(2) at an electric field of 1 MV/cm were readily achievable in the a s-deposited films. These properties are superior to those for layers grown by any other technique and annealed at significantly higher temperatures of 700-800 degreesC. (C) 2000 American Institute of Physics. [S0003-6951(00)0 4847-6].