Fracture toughness, adhesion and mechanical properties of low-K dielectric thin films measured by nanoindentation

The semiconductor industry is gradually moving from well-established AlySiO technology to the new Cuylow-k interconnects, 2 which brings a challenge in terms of poor thermal andyor mechanical properties of low-K dielectric films. Extensive nanoindentation studies have been undertaken on organo-silicate glass (OSG) low-K films to explore their mechanical and fracture properties. A cube corner indentation method was used to measure the fracture toughness of the OSG films, which ranges from 0.01 to 0.05 MPaØm . Film fracture was also observed during superlayer indentation adhesion testing. Interfacial cracks kinked into the film 1y2 itself, indicating competition between adhesive and cohesive failure mechanisms. Given that the crack propagates through the low-K, critical stress intensities on the order of 0.05 MPaØm are estimated. This is also consistent with the upper bound 1y2 calculations of 0.06 MPaØm , based on spontaneous film fracture at a critical film thickness of 3 mm due to tensile residual 1y2 film stress relief. 2003 Elsevier Science B.V. All rights reserved.