Vv. Afanasev et al., NECESSITY OF HYDROGEN FOR ACTIVATION OF IMPLANTED FLUORINE IN SI SIO2STRUCTURES/, Applied physics letters, 63(21), 1993, pp. 2949-2951
The elimination of trapping centers in Al/SiO2/Si structures by means
of fluorine ion implantation was studied in oxides with various conten
ts of hydrogen. It was shown that significant reduction in the density
of electron and hole traps in the bulk of oxide may be achieved only
in the presence of hydrogen in the system (wet oxide, or post-metalliz
ation anneal in a hydrogen containing ambient). Similarly, suppression
of the generation of Si/SiO2 interface states by radiation is also ob
served only in hydrogen containing systems. The results suggest that d
efect precursors such as weakly bonded hydrogen and strained Si-O bond
s are eliminated by the fluorine and that hydrogen is necessary for th
is elimination. It is proposed that H facilitates the F transport by f
ormation of HF molecules.