Nuclear Tracer Measurements of Low Temperature Water Diffusion in Silicon Dioxide (SiO2) Thin Films.

摘要

As part of an investigation of the physical basis underlying aspects of MOS processing technology, we have studied the transport mechanism by which water diffuses through thin SiO2 films. This process is responsible for the formation of oxide layers on silicon wafers by means of thermal steam oxidation, which is frequently employed in the manufacture of integrated circuit devices. We have performed tracer diffusion measurements involving network 180, demonstrating the importance of oxygen exchange between the Si02 network and molecularly dissolved water. We have found that in the presence of water, bound network oxygen diffuses through Si02 as a constituent of molecularly dissolved water. Employing methods common to state-of-the-art semiconductor technology, the central region within a thermal oxide layer grown on silicon was enriched with immobile 180 by ion implantation. After heating in atmospheres with different water contents, the extent of 180 diffusion was determined by observing changes in the concentration profile (i.e. the chemical concentration as a function of depth) of implanted 180 by means of nuclear resonance profiling.