28nm Planar Flow

Device Context and Integration Logic

The CESL Nitride Deposition step is inserted in the MOL contact module to form a conformal silicon nitride contact etch stop layer above the fully defined transistor gate, spacers, and source/drain regions, immediately after resist and oxide etch-back operations have exposed a planarized topography suitable for liner deposition [P2]. This layer provides a chemically and physically robust interface that separates the active device structures from the sub…

• [High] Excessive or Incorrect Intrinsic Stress: If the deposited silicon nitride exhibits intrinsic stress outside the mechanically stable window, elastic energy stored in the film can drive crack formation or delamination, or transmit unfavorable stress into the channel that degrades carrier mobility through the piezoresistance effect, as demonstrated for stressed CESL films [P3].