Boron Electrical Activation in SOI Compared to Bulk Si Substrates

We investigate the influence of the buried Si/SiO₂ interface in Silicon-On-Insulator (SOI) substrates on B electrical activation by comparing experimental data and atomistic simulations in bulk Si and SOI materials. In crystalline Si, the effect of the Si/SiO₂ interface on the formation of B clusters is practically negligible because they are formed rapidly and locally in the region with high B and Si interstitial concentrations. During post-implant anneal less diffusion occurs and a slight acceleration of B activation is observed, as the Si/SiO₂ interface increases the removal of Si interstitials and facilitates B cluster dissolution. In pre-amorphized Si, B clusters form during the recrystallization of the pre-amorphized layer. Therefore, the effect of the Si/SiO₂ interface is mainly related to its influence on end of range defect (EOR) evolution after regrowth which in turn affects B deactivation and subsequent reactivation. Our simulations show that slightly less B deactivation occurs in SOI compared to bulk Si samples since the Si/SiO₂ interface accelerates EOR defect dissolution. The effect is more significant as EOR damage is closer to the Si/SiO₂ interface compared to the distance from EOR damage to the silicon surface.