E1' CENTERS IN BURIED OXIDE LAYERS FORMED BY OXYGEN ION-IMPLANTATION INTO SILICON

Electron paramagnetic resonance measurements have been made of E1' centres in n-type (100) silicon wafers implanted between 500 and 600-degrees-C with higgh doses (almost-equal-to 10(18) O+ cm-2) of 200 keV O+ ions. In the as-implanted state E1' centres exist only in oxide precipitates but a high concentration (almost-equal-to 2 x 10(18) cm-3) of E1' centre precursors is present in the buried oxide layer; the latter can be converted to E1' centres by relatively small doses of ionizing radiation. The E1' centres in the buried layer anneal in a similar way to those formed in thermally grown a-SiO2 by ion implantation: they undergo reversible annealing in the temperature range almost-equal-to 100-350-degrees-C and anneal irreversibly at temperatures greater-than-or-similar-to 350-degrees-C. The E1' centres in the oxide precipitates have the same irreversible annealing behaviour but show no low temperature reversible annealing.