Adapting Interconnect Technology to Multigate Transistors for Optimum Performance

Beyond the 22-nm technology node, interconnect parasitics are increasingly contributing to the degradation of circuit performance. Thus, the focus is on optimizing interconnect parasitics in order to achieve optimum performance. The increased total device capacitance and the reduced device resistance of multigate transistors amplify the importance of wire resistance in circuit delay. In this paper, the impact of interconnect resistance on the circuit performance is weighed against interconnect capacitance, and less aggressive wire width and thickness scaling are proposed. This analysis is carried out based on the results from fully timing-closed, GDSII-level layout of circuit blocks, for the 11- and 7-nm technology nodes. The sensitivity of circuit power dissipation and signal noise to interconnect dimensions is assessed in detail. This approach compromises wire capacitance and gradually renders it important in circuit delay. The circuit performance enhancement by air-gap (AG) interconnect technology is studied with the traditional BEOL scaling versus the proposed wire sizing. It is found that using the latter wire sizing approach with air-gap interconnects is more beneficial to circuit performance.