SUPPRESSION OF OXIDATION STACKING-FAULTS IN SILICON SEPARATION BY OXYGEN

Oxidation of the silicon overlayer in silicon separated by oxygen (SIMOX) is expected to create oxidation stacking faults (OSFs) since this process generates silicon interstitials in the active silicon layer. In spite of this process, recent results reveal that the density of OSFs is very low. A phausible mechanism which can explain the absence of OSFs in SIMOX is that silicon interstitials which are rejected from the silicon overlayer and SiO2 interface react with SiO2 of the buried layer to form SiO molecules (Si + SiO2 = 2SiO). These species can diffuse four orders of magnitude faster than silicon through the SiO2 buried layer to the back interface where they are recombined by the reverse reaction owing to the absence of silicon interstitial supersaturation in this side.