Reliability Challenges with Ultra-Low k Interlevel Dielectrics

The adoption of ultra-low k dielectric materials in the pursuit of greater performance will pose reliability challenges quite unlike what we have previously experienced. The ultra-low k (ULK) dielectrics are completely different from the materials we have traditionally used. Unfortunately, the properties that make them desirable from an electrical point of view make them undesirable from a mechanical and environmental point of view. Low mechanical strength, low elastic modulus, rapid diffusion and susceptibility to dielectric breakdown are all characteristic of the ULK dielectrics. In this paper we review work we have performed in our laboratory to understand and characterize these new and temperamental materials.