Metal-Oxide-Semiconductor Structures with Two and Three-Region Gate Dielectric Containing Silicon Nanocrystals: Structural, Infrared and Electrical Properties

摘要

Two types of MOS structures, c-Si/SiO_x/Al and c-Si/SiO2/SiO_x/Al (x = 1.15 and 1.3) were prepared by thermal evaporation of silicon monoxide with thickness of ～ 100 nm on Si substrate or on thermal oxide. The effect of the annealing conditions on the gate dielectric properties was studied by TEM, FTIR and I-V measurements. Crosssectional TEM revealed that a two-step annealing process at 1000°C, first in N2 and then in N2+O2 atmosphere leads to formation of two regions in the SiO_x layer: a homogeneous amorphous region, free of nanocrystals close to the top surface and a region with nanocrystals underneath it. FTIR and electrical measurements showed that the top region is with properties close to that of stoichiometric SiO2.