Damascene copper integration impact on electomigration and stress migration

Abstract

We performed electromigration (EM) and stress migration (SM) stressing to study the effect of liner / Cu seed sidewall coverage and thickness; pre-Cu chemical-mechanical polish (CMP) anneal; and post-Cu CMP dielectric cap deposition. EM studies were: performed on narrow (w∼0.25μm) or wide (w∼1.8μm) single damascene ∼0.3μm tall wires with a tungsten stud contact below (C1-M1); and narrow (w∼0.25μm) dual-damascene M2 or M3 Cu wires ∼0.3-0.5μm tall with vias above or below. SM studies were performed on wire mazes and via chain structures. Standard physical vapor deposition (PVD) or first generation ionized PVD films were used for the TaN/Ta liner and Cu seed layer. Wafers omitting the pre-Cu CMP anneal had < 1/2 hour delay between electroplated (ECP) Cu deposition and Cu/Ta CMP to minimize room temperature Cu rccrystallization. © 2006 Materials Research Society.