In this work, we present detailed studies of two integration schemes for an aluminum-wire/tungsten-plug-based multilevel ultralarge scale integration (ULSI) interconnect module for subquartermicrometer complementary metal oxide semiconductor (CMOS) technologies, and discuss the benefits and drawbacks of each of them primarily from a process integration point of view. We demonstrate that an etch stop (ES) integration scheme in which the via etch stops on the TiN cladding layer could result in significantly improved via electromigration performance compared to an over etch (OE) integration scheme in which the via is overetched into the underlying Al(Cu). We also identified several highly detrimental early failure modes associated with the OE structure, including contamination-induced stress void formation underneath the via, the metal extrusion inside the via, and the metal corrosion at the bottom of the via, and showed that such early failure modes could be prevented in the ES integration scheme. Even though there were some small penalties in the device performance in the ES integration scheme, the benefits in the reliability and the better tolerance to manufacturing process variation clearly justify the adoption of this robust multilevel ULSI interconnect module for subquartermicrometer CMOS technologies.