Developmnet of a robust Ultra-Low-k film and carbon replenishment for reliable BEOL interconnect

A challenge to scale down back-end-of-line (BEOL) interconnect has been mandatorily required to meet electrical performance for next generation device nodes. Accordingly, the researchers have made intensive efforts to fabricate a robust and high-performing inter-metal dielectric (IMD) because the BEOL interconnect is mostly composed of metal lines and IMD themselves. Particularly, the IMD layer should be robust enough to sustain various damage-causing processes such as etch, strip during device integration to preserve their electrical performance. However, it is highly limited to find proper material properties sustaining their performance even after harsh damages. Therefore, in this paper, we introduce a combination of technologies to form a robust ultra-low-k (ULK) film and to recover damaged portion of it by replenishing carbon materials. The IMD film displayed the great robustness to etch, strip damages owing to their bridged carbon bonds. In addition, a brand-new technology called k-recovery process can effectively recover degraded a k-value, and carbon bonds of damaged IMD by simple post treatment. As a result, we achieved the capacitance gain ~ 3.8% on logic device by improving a BEOL IMD itself.