High-resolution TEM/STEM analysis of SiO2/Si(100) and La2O3/Si(100) interfaces

We have performed direct observations and elemental analyses of SiO2/Si(100) and La2O3/Si(100) by spherical aberration-corrected transmission electron microscopy (TEM) / scanning TEM (STEM) and ldquocombinatorial analysesrdquo by energy dispersive X-ray analysis (EDX) and electron energy loss spectroscopy (EELS). In SiO2/Si(100), the interfacial structures have been clearly observed without artificial image contrast. Atomic steps and defects on the Si(100) surfaces have been accurately identified. In La2O3/Si(100), epitaxial double layers have been observed after depositon at room temperature. These layers have been identified with lanthanum silicate and silicon oxide including a small amount of lanthanum atoms. Annealing at 500degC for 10 min have caused growth of both of the layers and exclusion of the lanthanum atoms from the silicon oxide layer. The growth mechanism of the layered structure and its influences on gate properties in MOSFETs have been discussed based on our experimental data.