SPECTROSCOPIC ELLIPSOMETRY STUDY OF THE INTERFACIAL STRESSES AND THEIR CORRELATION WITH MICROVOIDS IN VERY THIN THERMALLY GROWN SIO2-FILMS

The intrinsic stress in the interfacial region of the SiO2/Si interfac e was estimated, with in situ spectroscopic ellipsometry (SE) during a dry etching process of thermally grown oxides, to be 3.8 kbar. Furthe rmore, the microvoids distribution, in very thin thermally grown SiO2 films studied with ex situ SE, was found to be correlated with the str ess distribution in the direction of the oxide growth. The voids volum e fraction exhibits an exponential decay behavior versus the oxidation time with a relaxation time similar to the strain relaxation time rep orted in the literature. The SE-calculated voids relaxation time, 60 m in (12 min) for oxides grown at 900 degrees C (1000 degrees C), is als o predicted from IR results obtained through the dependence of the Si- O stretching frequency on the oxidation time. (C) 2995 American Instit ute of Physics.