Solid phase epitaxy versus random nucleation and growth in sub-20 nm wide fin field-effect transistors

The authors investigate the implications of amorphizing ion implants on the crystalline integrity of sub-20 nm wide fin field-effect transistors (FinFETs). Recrystallization of thin body silicon is not as straightforward as that of bulk silicon because the regrowth direction may be parallel to the silicon surface rather than terminating at it. In sub-20 nm wide FinFETs surface proximity suppresses crystal regrowth and promotes the formation of twin boundary defects in the implanted regions. In the case of a 50 nm amorphization depth, random nucleation and growth leads to polycrystalline silicon formation in the top ∼25 nm of the fin, despite being only ∼25 nm from the crystalline silicon seed.