Evolution of implantation-induced defects in silicon-on-insulator during rapid thermal annealing

The implantation, a key step of layer transfer technology, directly impacts the device layer quality of Silicon-on-Insulator (SOI) substrates. Hence, developing characterization methods for implantation-induced defects is particularly important. In this work, rapid thermal annealing (RTA) is applied to reveal the evolution of surface defects in the device layer of 300 mm as-split SOI. Transmission electron microscopy observations demonstrate that these defects, which consist of nano-bubbles and microcracks, are introduced by light-gas implantation. Indeed, the defect is exposed through coalescence of microcracks as well as diffusion of silicon during RTA. The depth of defects reaches around 1.3 nm at 1473 K, and no significant change is observed under increased thermal budget. In addition, these defects can be removed by sacrificial oxidation, and the critical oxide thickness coincides with the thickness of the damaged layer in the as-split SOI. SIMS and Raman analyses reveal that RTA triggers the formation of microcracks, while oxidation promotes hydrogen segregation at SiO2/Si interface, which, in turn, suppresses such defects. Moreover, gaseous HCl etching is employed to validate the feasibility of using RTA for characterizing the implantation-induced defects in the device layer of 300 mm as-split SOI.