Blockage of the annealing-induced Si/SiO2 degradation by helium

Electrical degradation of Si/SiO2 structures caused by postoxidation annealing was comparatively studied in noble gas (He, Ne, Ar), vacuum, and N-2 ambient. Helium is found to significantly retard the generation of defects responsible for the low-field conductivity of ultrathin oxides and the hole trapping in SiO2. The physical mechanism of the blockage effect is attributed to the occupation of interstitial cavities in SiO2 by the noble gas atoms that prevent interfacial reaction between Si and SiO2. (C) 1999 American Institute of Physics. [S0003-6951(99)01902-6].