FINFET CIRCUITS EMPLOYING REPLACEMENT N-TYPE FET SOURCE/DRAIN (S/D) TO AVOID OR PREVENT SHORT DEFECTS AND RELATED METHODS OF FABRICATION

Fin Field-Effect Transistor (FET) (FinFET) circuits employing a replacement N-type FET (NFET) source/drains (S/D) are disclosed. The disclosed method for forming a FinFET circuit includes forming two P-type epitaxial S/Ds (epi-S/Ds), one on the fin in the P-type diffusion region and one on the fin in the N-type diffusion region, forming a boundary layer to isolate the P-type epi-S/Ds, and then replacing the P-type epi-S/D under the boundary layer in the N-type diffusion region with an N-type epi-S/D. A mask is employed in steps for replacing the P-type epi-S/D with an N-type epi-S/D in the disclosed method but differs from the mask in the previous method such that vulnerability to variations thereof is reduced. The mask in the disclosed method has a larger acceptable range of variation within which no defects are created, so the disclosed method is less vulnerable to process variation and prevents short defects.