Ultra thin Oxide by Chemical Vapour Oxidation of Si

摘要

Continued MOSFET scaling necessitates the use of high-k materials which in turn need an ultra thin (<0.6nm) SiO_2 buffer layer between the high-k material and the silicon substrate, to obtain a better interface. In this paper a novel technique to grow extremely thin (as low as 0.6 run) oxide by nitric acid vapour at low temperature and effect of ac anodization on these oxides are discussed. The effective oxide thickness obtained for these chemical oxides has been found to be ranging from 0.6 nm to 1.5 nm. C-V, I-V and reliability characteristics have been studied. The oxide thickness increases with increase in molarity of the HNO_3. At an electric field of 10 MV/cm, the leakage current density for the thinnest oxide is 0.6 A/cm~2. These values are better than those for oxides grown in HNO_3 solution. Anodization improved the quality of the chemical vapour oxides further.