Novel Air-gap Formation Technology Using Ru Barrier Metal for Cu Interconnects with High Reliability and Low Capacitance

Abstract

A novel technology for obtaining low-capacitance Cu interconnects with air gaps has been proposed. Using a Ru barrier metal as a self-mask, a Cu interconnect was effectively protected from losing its cross-sectional shape during the intermetal dielectric etching process. The wiring capacitance with air-gaps was about 30% lower than that of the conventional low-k (k = 2.65)/Cu structure without air-gaps. The time-dependent dielectric breakdown (TDDB) lifetime of the air-gap interconnect with a Ru barrier was 100 times longer than that of the low-k/Cu structure. These results indicate that an air-gap interconnect with a Ru barrier metal can be an effective solution to boost the circuit operating speed and to reduce the power dissipation without the degradation of interconnect reliability for devices of 45 nm nodes and beyond.

In-situ Spectroscopic Ellipsometry of the Cu Deposition Process from Supercritical Fluids: Evidence of an Abnormal Surface Layer Formation

“…17,49) 4.3 Substrate effects on initial growth of Cu 4.3.1 X layer development Ru is now gaining a lot of attention in LSI metallization. For example, uses as a barrier metal [50][51][52] and as a seed/ liner [53][54][55] metal have been proposed. It has been reported that Cu nucleates and grows promptly on Ru.…”