POSITIVE CHARGING OF BURIED SIO2 BY HYDROGENATION

Simple hydrogen annealing of the buried oxide (BOX) of state-of-the-art separation by implanted oxygen material in the range 450-700-degrees-C was found to introduce net positive charge in the BOX with areal densities up to 5X10(12) elem. charges cm-2, while H-2 annealing in the range 700-1000-degrees-C was observed to activate a neutral state. Both processes appeared reversible upon appropriate vacuum annealing. The positive charge in the BOX is detected using electron spin resonance of a positive BOX-charge-induced signal in Si. The results are interpreted in terms of a two-state model which describes the trapping of hydrogen at a reactive site yielding an either positively charged (activation temperature T(A) almost-equal-to 450-degrees-C) or neutral (T(A) almost-equal-to 715-degrees-C) state, based on hydrogen incorporation into oxygen vacancies (Si-Si bonds).