Thermal oxidation-induced strain in silicon nanobeams

Single crystal silicon beams of sub-micron thickness were fabricated from the device layer of SIMOX type silicon-on-insulator wafers. The beams were thermally oxidized at 950°C in dry oxygen and the oxide was subsequently removed. As a result of the oxidation, there is a small but measurable accumulation of strain, which increases with the reduction of the beams´ thickness. The cause of this strain is not presently known, but A model is proposed based on the injection of self-interstitial silicon atoms from the oxidation front.