45 nm-node BEOL integration featuring porous-ultra-low-k/Cu multilevel interconnects

Abstract

45 nm-node multilevel Cu interconnects with porous-ultra-low-k have successfully been integrated. Key features to realize 45 nm-node interconnects are as follows: 1) porous ultra-low-k material NCS (nano-clustering silica) has been applied to both wire-level and via-level dielectrics (what we call full-NCS structure), and its sufficient robustness has been demonstrated; 2) 70-nm vias have been formed by high-NA 193 nm lithography with fine-tuned model-based OPC and multi-hard-mask dual-damascene process - more than 90% yields of 1 M via chains have been obtained; 3) good TDDB (time-dependent dielectric breakdown) characteristics of 70 nm wire spacing filled with NCS has been achieved. Because it is considered that the applied-voltage (Vdd) of a 45 nm-node technology will be almost the same as that of the previous technology, the dielectrics have to endure the high electrical field. NCS in Cu wiring has excellent insulating properties without any pore sealing materials which cause either the k/sub eff/ value or actual wire width to be worse.