Copper Contact for 22 nm and Beyond: Device Performance and Reliability Evaluation

We demonstrate the device performance benefit of Cu contact over W contact using high-κ/metal gate CMOS devices. The ring oscillator (RO) device of Cu contact showed reduction in external resistance, which resulted in an increase in drive current by 5% for both nFET and pFET devices. The delay on the gate-cap-loaded RO improved by 5%-7% with Cu contact. We evaluated device reliability tests for gate dielectric breakdown, positive-bias temperature instability, negative-bias temperature instability, and hot carrier injection on 32- and 22-nm-node devices with Cu contact. The reliability results for the Cu contacts with the reliable barrier layer and good gap fill are comparable to those of W contacts.