High-resolution transmission electron microscopy and electron energy-loss spectroscopy (EELS) were used to investigate La2O3/SiO2/Si structures. The La2O3 layers were deposited on thermal SiO2 on silicon, followed by rapid thermal annealing treatments at 600°C and 800°C in a nitrogen ambient. After annealing at 600°C, the oxide layers were amorphous. After an 800°C treatment, crystallites appeared in the original La2O3 layer, and the total oxide layer thickness increased by 17%, most likely due to the oxygen diffusion and reaction at the Si/SiO2 interface. EELS, using a 0.2 nm probe, showed that rapid thermal annealing at 600°C did not cause significant La diffusion into the SiO2 layer, whereas some intermixing was observed at 800°C. We use the observed microstructures to estimate equivalent oxide thicknesses. The results demonstrate that oxygen partial pressures and initial SiO2 thickness need to be carefully controlled to control SiO2 formation at the Si interface and to achieve target equivalent oxide thickness.
All Science Journal Classification (ASJC) codes
- Physics and Astronomy (miscellaneous)