Mechanical properties and fracture toughness of organo-silicate glass (OSG) low-k dielectric thin films for microelectronic applications

The integration of chemical vapor deposited organo-silicate glass (OSG) interlayer dielectrics (ILD) has challenged the IC industry to formulate new methods of metrology and characterization. The impact of nanoindentation to understand and screen for integrated circuit failure mechanisms that are mainly predicated upon OSG nano-porosity is discussed. Failure modes include poor mechanical strength, low material stiffness, and brittle fracture due to low cohesive and adhesive fracture toughness, a particular danger during chemical-mechanical polishing (CMP). By developing a methodology to predict failure modes, we are able to screen multiple candidate low-k materials. Nanoindentation measurements of elastic modulus, hardness, and fracture toughness and what they reveal about OSG porosity are discussed.