Dose loss and segregation of boron and arsenic at the Si/SiO2 interface by atomistic kinetic Monte Carlo simulations

Continuum downscaling of MOSFET devices requires of ultra-shallow junction formation. Performance of the source and drain from B and As low energy implant and subsequent annealing is seriously affected by the presence of the Si-SiO2 interface. Dopant loss due to segregation and dopant pileup at the interface during the transient enhanced diffusion (TED) are crucial phenomena for current and future CMOS devices. In this work we have implemented the Oh-Ward model [Y.-S. Oh, D.E. Ward, Tech. Dig. Int. Electron Devices Meet. 1998 (1998) 509] for the dopant behaviour at the interfaces integrated in an atomistic kinetic Monte Carlo simulator. Dopant traps at the interface can capture from or emit to either side of the interface. Furthermore, segregation of dopants and saturation of the interface by the presence of other species are also included. As a test of the model, low energy implants through a screen oxide have been simulated. When annealing these very shallow implants, a pileup at the interface is observed. The mechanisms involved in this process, as well as its dependence on the implant dose and energy are discussed.