Reduction of charge trappings and electron tunneling in SIMOX by supplemental implantation of oxygen

The reduction of excess-silicon related defects in SIMOX (separation by implantation of oxygen) by the supplemental implantation of oxygen is examined. The supplemental implant is 6% of the oxygen dose used to form the buried oxide, and is followed by a 1000°C anneal, in contrast to the >1300°C anneal used to form the buried oxide layer of SIMOX. The defects examined include shallow electron traps, deep hole traps, and silicon clusters. The radiation-induced shallow electron and deep hole trapping is measured by cryogenic detrapping and isothermal annealing techniques. The low-field (3 to 6 MV/cm) electron tunneling is interpreted as being due to a two-phase mixture of stoichiometric SiO₂ and Si clusters at a few nm in size. Single and triple SIMOX samples have been examined. All of the defects are reduced by the supplemental oxygen processing. Shallow electron trapping is reduced by an order of magnitude. The low-field electron tunneling due to Si clusters is also significantly reduced