Master of Science / Department of Chemical Engineering / James H. Edgar / Silicon oxidation has been the cornerstone of the semiconductor industry for many years,
so understanding and being able to predict the oxidation process is paramount. The most popular
model to date is the Deal-Grove model for the thermal oxidation of planar silicon surfaces. The
Deal-Grove model owes its popularity to the overall simplicity in which it was derived and the
accuracy in which it predicts the oxidation of planar silicon geometries. Due to this popularity
and accuracy it is desirable to extend the Deal-Grove model beyond flat surfaces to other
geometries such as cylinders and spheres. Extending the Deal-Grove model to these types of
geometries would allow the prediction of the oxidation of silicon nano-wires and silicon nanocrystals.
Being able to predict the oxidation is attractive due to the recent progress of integration
of silicon nano-wires and silicon nano-crystals into microelectronic devices.
Prediction of the oxidation of silicon cylinders (nano-wires) and spheres (nano-crystals)
by simply utilizing the established planar Deal-Grovel model results in highly exaggerated oxide
thicknesses compared with empirical data. This exaggeration for small silicon cylinders and
spheres is due to the effects of the reduction in the available surface area for oxidation along with
the stress induced due to the volumetric expansion and viscous flow of the oxide on non-planar
surfaces. These stress effects retard the oxidation rate in non-planar silicon geometries with
respect to flat surfaces. This reduction in the oxidation rate reduction is caused by the normal
compressive stress which is normal to the SiO[subscript]2/Si interface due to the volumetric expansion
during oxidation. This compressive stress reduces the reaction rate constant at the SiO[subscript]2/Si
interface and thus retards the overall oxidation rate for silicon cylinders and spheres with respect
to planar silicon. The focus of this paper will be to contrast cylindrical and spherical versions of
the Deal-Grove model to the well established planar version. Surface area and stress effects will
also be explored as they help explain the reduction in the oxidation rate for non-planar silicon
geometries.
| Identifer | oai:union.ndltd.org:KSU/oai:krex.k-state.edu:2097/1394 |
| Date | January 1900 |
| Creators | Lemme, Brian D. |
| Publisher | Kansas State University |
| Source Sets | K-State Research Exchange |
| Language | en_US |
| Detected Language | English |
| Type | Report |
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