Hydrogen interactions with delocalized spin centers in buried SiO2 thin films

Abstract

Defect centers have been investigated in bonded and etchback silicon-on-insulator materials following irradiation using electron paramagnetic resonance (EPR). Three different EPR centers are created in the top 0.1 μm of the SiO2 dielectric by either x-ray irradiation or vacuum ultraviolet (VUV) illumination. Two of the defects are the classic E′ center (⋅Si≡O3) and the amorphous silicon center (⋅Si≡Si3). The third EPR active defect center is characterized by g=2.0025 with an effective line width of 1.1 G. Longer irradiation times transform this new center into a hydrogen-related defect as observed by its two hyperfine lines split by 23.1 G. It appears that this defect is positively charged when EPR active. Using conventional capacitance versus voltage techniques, it is also found that irradiation leads to the generation of positive charge in the dielectric. This charge is located near the bottom Si/SiO2 interface, opposite the interface at which the paramagnetic centers are located.