Accelerated crack growth of nanoporous low-k glasses in CMP slurry environments

Considerable efforts have been directed at integrating nanoporous low dielectric constant (LKD) materials into the interconnect structures of high-density integrated circuits. The reliable fabrication of devices containing these fragile materials is, however, a significant technological challenge due to their high propensity for mechanical failure during all levels of processing and subsequent packaging operations in which they are subjected to mechanical loads in the presence of aggressive aqueous environments, such as chemical mechanical planarization (CMP). Here we demonstrate the significant effect of CMP solution chemistry on interfacial adhesion and crack growth rates in nanoporous LKD thin-films as well as lithographically patterned structures containing copper and LKDs. A new mechanism of accelerated cracking in H₂O₂ environments is revealed.