Dense SiOC cap for damage-less ultra low k integration with direct CMP in C45 architecture and beyond

Deposited on a porous a-SiOC:H intermetal dielectric (IMD), a dense a-SiOC:H cap was successfully integrated in a C45 dual damascene architecture. The paper demonstrates that, stopping the CMP with around 10nm of the cap left, the IMD integrity is preserved. As a consequence, a 3.5% decrease in RC delay, a 7.3% decrease in IMD integrated k-value and an increase of the time to failure by a 100 factor are reached relative to direct CMP. The cap also allowed to achieve straight lines and to improve the lines height uniformity as if CMP stopped on the IMD.