Microscopic nature of border traps in MOS oxides

Abstract

We show that enhanced hole-, electron-, interface-, and border-trap generation in irradiated Si/SiO/sub 2//Si systems that have received a high-temperature anneal during device fabrication is related either directly, or indirectly, to the presence of anneal-created oxygen vacancies. The high-temperature anneal results are shown to be relevant to understanding defect creation in zone-melt-recrystallized silicon on insulator materials. We observe the electron paramagnetic resonance (EPR) of trap-assisted hole transfer between two different oxygen vacancy-type defects (E'/sub /spl delta///spl rarr/3 E'/sub /spl gamma// precursor) in hole injected thermal SiO/sub 2/ films. Upon annealing the hole injected Si/SiO/sub 2/ structures at room temperature, the E'/sub /spl delta// center transfers its hole to a previously neutral oxygen vacancy (O/sub 3//spl equiv/Si-Si/spl equiv/O/sub 3/) site forming an E'/sub /spl gamma// center. This process, also monitored electrically, shows a concomitant increase in the border-trap density that mimics the growth kinetics of the transfer-activated E'/sub /spl gamma// centers. This suggests that both effects are correlated and that some of the transfer-created E'/sub /spl gamma// centers are the entities responsible for the border traps in these devices. One implication of these results is that delayed defect growth processes can occur via slow trap-assisted hole motion in SiO/sub 2/. >