In this work we report the adhesion of a thin Tantalum (Ta) barrier films deposited on nanoporous dielectric substrates (Xerogel and Methyl Silesquioxanes (MSQ)). The high compressive stresses in the Ta barrier layer lead to spontaneous delamination from the underlying substrate resulting in a telephone cord like morphology, which allows the measurement of critical interfacial adhesion (fracture) energy. The fracture energy of Ta barrier films on different porous substrates is evaluated using the above two methods and the resulting differences are explained. Fracture energy varies inversely as a power law with the dielectric pore size indicating pores are essential to delamination in the barrier-dielectric interface. The observed trend of fracture energy is related to other mechanical properties of the porous substrate offering insights into the underlying mechanisms governing fracture of films deposited on porous substrates.
