Characteristics of interfacial strains developed in silicon by wet O₂ oxidation

The interfacial strains that developed in silicon wafer during wet oxidation were studied using convergent electron beam diffraction (CBED) analysis. For the observation of the stacking faults at the Si/SiO₂ interface, the oxide layer was removed by hydrofluoric acid and the silicon surface was etched. The lattice strain was tensile at the interface and diminished sharply towards zero at about 1.5 μm from the Si/SiO₂ interfaces. Tensile thermal strain was observed at the interface because the thermal expansion coefficient of silicon is five times larger than that of SiO₂.