Robust multilevel interconnects with a nano-clustering porous low-k (k<2.3)

For 65 nm node devices and beyond, we developed a high performance porous SOD materials, nano-clustering silica (NCS). Our original nano-clustering technique can control pore sizes to less than 2.8nm and achieve a homogenous pore distribution without the use of any template materials. NCS films combine a very low dielectric constant (k<2.3) with high mechanical strength; the elastic modulus is 10 GPa and the hardness is greater than 1.0 GPa. We have successfully fabricated 200nm-pitch hybrid-ULK/Cu interconnects by application of NCS to trench layers and SiOC to via layers. The structures exhibit satisfactory electrical characteristics, reliability and framework strength for the severe requirements of 65nm node devices. 10-level interconnects using NCS for the intermediate layers were fabricated without any delamination or cracking. The results of thermal-cycle (TC) and pressure temperature humidity stress (PTHS) tests also showed the high practical reliabilities. The NCS/copper multilevel interconnects meet the 65nm-node requirements for BEOL.