28nm Planar Flow

Device Context and Integration Logic

The Spacer-1 Nitride Deposition step is introduced immediately after polysilicon gate patterning to establish a conformal dielectric layer on the vertical sidewalls of the gate structure, which will later be transformed into a self-aligned sidewall spacer through anisotropic etching [T1]. This spacer defines the lateral offset between the gate edge and the subsequent heavy source/drain implants, enabling the formation of lightly doped drain (LDD) and ext…

• [High] Spacer Width Non-Uniformity: Non-conformal or density-nonuniform nitride deposition leads to variation in etched spacer width, which alters effective channel length and exacerbates threshold voltage variability through enhanced short-channel effects [P1].