Optical and interface-based methods of defect engineering in silicon

Ion implantation is widely used in the microelectronics industry for fabrication of source and drain transistor regions. Unfortunately, implantation causes considerable damage to the substrate lattice rendering most of the implanted dopant electrically inactive. Rapid thermal annealing (RTA) heals the damage by rapidly heating the substrate with a high-power light source. This work uses experiments and continuum-based modeling to develop a scientific understanding of how illumination and the state of the Si-SiO 2 interface affect diffusion of defects during annealing. The optical method elucidates the origin of a nonthermal influence of illumination on boron diffusion. The results show that photostimulated changes in diffusion stem primarily from light interacting with interstitial clusters as they dissociate rather than point defect-mediated changes to steady-state diffusion. An additional mechanism of photostimulated diffusion has been discovered: light interacting with electrically active defects at the Si-SiO2 interface causes variations in the electrostatic field. This interface-based method serves as a scientific foundation for controlling diffusion of silicon interstitials through the Si-SiO2 interface using argon ion bombardment. The results show that the disrupted interface causes "uphill" diffusion by increasing interstitial absorption at the interface.