CONDUCTING AND CHARGE-TRAPPING DEFECTS IN BURIED OXIDE LAYERS OF SIMOX STRUCTURES

The conducting defects and charge-trapping defects in the buried oxide (BOX) of SIMOX structures depend on the processing conditions. Sample s implanted with the oxygen ion beam in a channeling direction of the Si wafer contain more defects of both types than those prepared in an off-channel mode; thus, a correlation between excess silicon in the ox ide forming Si clusters (amphoteric photosensitive defects) and the de nsity of conducting defects may exist. We suggest that;interstitial Si atoms generated during the implantation/anneal process form filaments in structural channels in the BOX. However, the density of conducting defects may be influenced by other factors, such as contamination and /or the extent of the localization (lateral inhomogeneity) of the trap ping defects. The defects in the BOX are distributed in a laterally in homogeneous manner. This may result in varying density of conducting d efects for the same integrated density of amphoteric defects. The obse rvation of defects in the top Si layer and their correlation with cond ucting defects in the BOX indicate the possible involvement of some co ntaminant in the formation of conducting channels in the BOX.