DETERMINATION OF SILICON EVAPORATION RATE AT 1200-DEGREES-C IN HYDROGEN

Separation by implanted oxygen silicon wafers have been investigated w ith cross-sectional transmission electron microscopy after annealing a t 1200 degrees C in argon as well as in hydrogen. It is observed that the buried oxide has experienced little change in the thickness, which is ascribed to the low hydrogen solubility in the crystal (about 3x10 (15) cm(-3)) and provides a natural mark to measure the thickness vari ation of the top silicon directly. The evaporation rate as determined in this method is less than 0.1 nm/min with an accuracy of +/-0.1 nm/m in, at least two orders of magnitude lower than reported in previous i nvestigations. (C) 1995 American Institute of Physics.