THERMAL OXIDE-GROWTH AT CHEMICAL-VAPOR-DEPOSITED SIO2 SI INTERFACE DURING ANNEALING EVALUATED BY DIFFERENCE X-RAY REFLECTIVITY/

The x-ray interference technique has been applied to evaluate the stru ctural changes of high temperature grown chemical vapor deposited (CVD ) SiO2 film under several post annealing conditions. In annealing abov e 800 degrees C in O-2 ambient, a thermal oxide growth has been found at the CVD SiO2/Si interface, and its precise thicknesses have been de termined. The estimated diffusion coefficient of the oxidant in CVD fi lm was about three times larger compared to that of thermal oxide. A t hreshold voltage shift in the oxide was found to strongly correlate to the thickness of the thermal oxide rather than to thermal modificatio ns of the CVD SiO2 itself. (C) 1997 American Institute of Physics.