CHARACTERIZATION OF ELECTRON TRAPS RESULTING FROM OXYGEN PRECIPITATION IN Cz SILICON.

CZ wafers have been heat treated with either a 2 step anneal or a single step anneal. Deep level transient spectroscopy and minority carrier lifetime measurements were obtained on processed wafers containing diode-capacitor arrays. Wafers from the seed end of the crystal with the 2 step anneal showed 2 electron traps E1, and E2; the dominant trap E1 is shown to correlate with generation lifetime. Wafers implanted with oxygen at 400 keV or 3. 5 MeV with doses of 3 multiplied by 10**1**5 and 1 multiplied by 10**1**6 atoms cm** minus **2 with similar heat treatments reveal electron traps with the same energies as those observed in the unimplanted samples. The high dose samples show a much more complicated spectra, in which E1 and E2 are present. TEM analysis of the seed end unimplanted samples with 2 step anneal show plate type precipitates with punched out loops and dislocations. The tang-end showed octahedral precipitates. The cross sectional view of the implanted samples reveal the precipitates and dislocation loops in a well defined layer.