28nm Planar Flow

Device Context and Integration Rationale

The RV Nitride Deposition step is inserted immediately after copper electroplating and in-situ annealing to form a dielectric barrier and etch-stop layer on top of the completed Cu interconnect surface, preventing copper diffusion and chemical interaction with subsequent dielectric films [P1]. The preceding Cu anneal stabilizes grain structure and relieves intrinsic stress, after which direct exposure of Cu to oxidizing or silane-based ambients would…

• [High] Copper Diffusion Through Nitride: If the deposited nitride network is insufficiently dense or contains interconnected defects, copper atoms can migrate through the film under thermal or electrical driving forces, leading to dielectric contamination and increased leakage, following the diffusion mechanisms described for BEOL barriers [P1].