Study of viscoplastic deformation in porous organosilicate thin films for ultra low-k applications

This letter reports experimental observations evidencing the viscoplasticity of porous organosilicate glass thin films under conditions pertinent to their application in advanced low-k/Cu interconnect technology. Specifically, it is found that porous SiCOH thin films exhibit a significant level of viscoplasticity with a rate sensitive to the porosity, the degree of plasma damage, and hydration reaction when tested using a ball indenter at 150-400 degrees C. The activation energy of the viscosity (1.25-1.45 eV) is measured to be far lower than the bulk glass (>4 eV), suggesting that the viscous flow is affected by the presence of defective bond-network such as Si-OH or Si-H bonds. (C) 2013 AIP Publishing LLC.